Truth in Sentencing

Truth-in-sentencing debate Learning Team B CJA/204 November 26, 2012 Deana Bohenek Truth-In-Sentencing Debate Opening Argument Truth-in-sentencing laws do not deter crime. The federal truth-in-sentencing law guarantees that certain violent offenders will serve at least 85% of their sentence  (Schmalleger, 2012). However, if the offender acts accordingly in prison, he or she can attain parole for good behavior. What about the victims? Victims do not want to hear this. If an offender is sentenced for 30 years, the victim wants justice and wants to see the full 30 years served.They do not want to see the offender getting released after 25 years. The truth-in-sentencing laws are the judges’ guideline when choosing the sentence of the offender. The law is a structured guideline for sentencing the offenders. However, the judge can deviate from the guidelines if there are mitigating and aggravating circumstances. Look at plea bargaining,  this is still a possibility even though t here are truth-in-sentencing laws in place. The offender knows that if they get caught, they can plea bargain for a lesser sentence and be back out on the streets sooner.Let me say it again, truth-in-sentencing laws do not deter crime. The offenders know they will get out of prison soon through a plea bargain or parole. They know they can avoid serving the full sentence that the judge imposed on him or her. The only way to deter crime and reduce recidivism is to abolish the possibility of parole and ensure that the sentence the judge renders is carried out to full-term. Obviously, to take away the option for parole would mean that the prison populations would increase. Well, we should take the funds left over from overhead to run the parole division and build more prisons to house these offenders.The longer we keep them off the streets, the safer society will be. Rebuttal Argument Each state has to look at the amount of money being spent to house each inmate they have in custody. Be cause the Truth-In Sentencing Law wants to keep the offender behind bars until they complete their entire sentence/term in prison no matter what the costs are to the public. Meaning, everyone’s hard earned income  (taxes) are used to keep them in their present place of occupancy. This law depletes the services we receive from our state revenues.We don’t have much say in the budget spending but we do see the increase in taxes used for each state program. I have to disagree with the statement made â€Å"The offenders know they will get out of prison sooner through a plea bargain or parole. †Ã‚   Not all offenders before or during their trial will know the outcome of sentencing. Many do not have the option for plea bargaining because plea bargaining depends on the severity of the crime committed. Instead, if the case went directly to trial, (this includes judge and jury) the accused might have a chance of plea bargaining.No plea bargaining makes the offender elig ible for a parole based on his or her behavior during incarceration and no plea bargaining being offered. But if society had no parole system, then the correctional system will have to face overcrowding in the institutions. The lack of Rehabilitation for said prisoner would be non-effective because there would be no programs such as work-time credit or good-time credit, which is the main reason why early release would benefit them. With those programs the time served by offenders would be less and would allow the offenders to enter back into society.The fear of re-entry of said offenders are the defense for keeping them locked up. These programs should be used for offenders that have this as a first offense on their record and have shown they can be productive in today’s society. Not all inmates are repeat offenders some are just non-violent offenses but carry a great penalty. When I was younger it was a big deal to go to jail because it showed most people that they were a â €Å"badass†, a badge of honor, and should be feared. In my eyes it was a waste of mind, body, and productive individual. Those same individuals found when they came out ithout a trade they were worthless and the only way to survive was crime and more time in jail. In Illinois, Governor Pat Quinn on October 2, 2012 has reinstated the program for â€Å"Good-time† releases,  a way to bring down the overcrowding in his state and federal prison system. Opening Argument Truth-in-Sentencing laws deter crime because they ensure that offenders are in prison for at least 85% of their sentence. Therefore, the convicted offenders stay in prison for longer periods and not able to commit additional crimes and endanger the member of society.TIS laws are the assurance of longer prison terms as punishment and serve as an effective deterrent from criminal actions to the serving offender and others who may be considering criminal acts. The laws provide the ability for the criminal just ice system to operate more effectively by lowering violent crimes as well punishing violent criminals. According  to the publication from  University  of Alabama at Birmingham (2005) citing data from Bureau of Justice Statistics, in the decade following the passage and implementation of the truth-in-sentencing laws in 1994, the arrests for violent crimes were reduced by 16% by the year of 2005.The TIS laws also limit some of the discretion of the judges and parole boards with regard to release of the offenders prematurely and being â€Å"too soft† on crime, thus eliminating the many possibilities for the offenders getting away without receiving the well-deserved punishment. The Bureau of Justice Statistics Special Report from January 1999 indicates that prior to the TIS laws violent offenders barely served half the length of their sentences. What kind of message did that send to the convicted or potential criminals?With the availability of TIS laws, criminal justice adm inistrators can build public confidence by ensuring that the just punishment is served to anyone breaking the law. In the article written by Joanna Shepherd published in the Journal of Law and Economics, she makes this statement: â€Å"Using a country-level data set, empirical results confirm that TIS laws deter violent offenders, increase the probability of arrest, and increase maximum imposed prison sentences. TIS laws decrease murders by 16%, aggravated assaults by 12%, robberies by 24%, rapes by 12%, and larcenies by 3%† (Shepherd,  2002,  p. 09). Today, more states are implementing the TIS laws and abolishing parole and indeterminate sentencing, demonstrating that the state legislature believes in this uniform application of justice processes and effectiveness of these laws in crime prevention. This information clearly shows that TIS laws are very effective in deterring crime by ensuring the stern and just punishment for offenders and sending the clear message to pot ential criminals that criminal behavior will be punished by lengthy imprisonment. Rebuttal ArgumentWhat about crime being committed in prisons around the world? Are we just going to ignore that fact because victimization is still happening across the boards of federal and state prisons? According to  a writer of The  New Yorker, Adam Gopnik, darkly described America prisons as â€Å"the moral scandal of America life. Prison rape is so endemic- more than seventy thousand prisoners are raped each year. † That is routinely held out as a threat, part of punishment to be expected. † (Gopnik, 2012). The National inmate survey reported that â€Å"An estimated 4. 4% of prison inmates and 3. % of jail inmates reported experiencing one or more incidents of victimization by another inmate or facility staff since admission to the facility  (Beck & Harrison, 2010). The total federal and state population in 2010 was 1,605,127, while the total jail population in 2009 was 767,62 0. This implies that there were over 94,000 victims subject to multiple violations (Beck & Harrison, 2010). No I don't agree with the fact that offenders being incapacitated for longer periods of time don't commit another crime. For people who want to do so, they will commit crimes anyway, and largely at that.Especially, the incentive behind good time credit is to have offenders behave in prison. If you lock them up in less than ideal conditions with no incentive to behave appropriately while incarcerated, they will be a population difficulty to control because they have nothing to lose. Earning good time credit gives them an insight to behave well inside. As for truth-in sentencing laws, I don't know if I  would actually say it is a deterrent or at least how much of a deterrent it  is, but I think it is  important nonetheless. Prior to 2003, legislation allowed for automatic emission of every sentence imposed to be reduced by one third (Chong, 2008). If the offender was made eligible for parole, a portion of that sentence is served under supervision in the community to enable their reintegration  into the community when released (Chong, 2008). Legislation introduced in 2003 abolished the automatic remission provision, so the sentence  imposed would more truly reflect the time to be served. In its place, legislation required courts to adjust the sentence actually imposed by one third, to reflect the abolition of automatic remission (Chong, 2008).What the government has done is  replace  automatic remission with reduction of sentence (Chong, 2008). The more things change, the more they remain the same. Sentences are more or less duration  for the same type of offenses (Chong, 2008). Some say the money being used for these criminals sitting in  jail should be more valuable of utilizing for work  time credits and more programs  for educational, substance abuse, psychiatric help programs for these offenders before being released out into the world again.I think it will better prepare themselves rather than not knowing what to do and all they are use to is the  jail's way of life in which they will end up back  in having that kind of mind set. References Beck, A. J. , & Harrison, P. M. (2010, August). Sexual Victimization in Prisons and Jails Reported by Inmates, 2008-09. Bureau of Justice Statistics, Retrieved from http://bjs. ojp. usdoj. gov/content/pub/press/svpjri0809pr. cfm Chong, P. (2008, June 19). The Truth about ‘Truth in Sentencing'. WAtoday. Retrieved from http://blogs. watoday. com. u/theverdict/2008/06/the_truth_about. html Ditton, P. M. , & Wilson, D. J. (1999, January). Truth in Sentencing in State Prisons. Bureau of Justice Statistics Special Report,  (NCJ 170032). Retrieved  from  http://bjsdata. ojp. usdoj. gov/content/pub/pdf/tssp. pdf Gopnik, A. (2012, January 30). The Caging of America. The New Yorker. Retrieved from http://www. newyorker. com/arts/critics/atlarge/2012/01/30/12030crat _atlarge_gopnik Schmalleger, F. (2012). Criminal Justice Today: An Introductory Text for the 21st Century, 11th ed. Upper Saddle River: NJ. Shepherd, J. M. (2002,

Ball bounce higher when it is warmed up Essay

Prediction I predict that for this experiment the higher the temperature, the more the ball will bounce. I put this down to the temperature is raised, the particles inside will gain energy therefore the higher the ball will bounce. Equipment For this experiment I will use the following equipment to do this experiment: – 1. Beaker 2. Bunsen burner 3. Splints 4. Tripod 5. Gauze 6. Thermometer 7. Squash Ball 8. Paper Towels 9. Meter Ruler 10. Tongs 11. Stop Clock 12. Safety goggles. Method Choose one yellow spot squash ball. This will be used throughout the experiment to ensure that the ball is made of the same rubber and same size. The experiment will be carried out on the hard floor tiles of the science laboratory. The area will be clean to ensure there are no irregularities on the surface. The ball will be heated to the required temperature by placing it in a beaker of heated water for one minute. To ensure the human body does not affect the temperature, tongs will handle it. Temp (? C) Temp (Kelvin). Results I am going to work out pressure and predicted hang time using the following formulas. This is how to work out pressure; P1 is Pressure 1, which is always 1. T1 is Time 1 and T2 is Time 2. This number changes as you work out To work out predicted hang time you use this formula. In this formula P1, P2 etc are Predicted hang time. This number changes as you work out   Temp (Kelvin) Pressure Predicted Hang time Actual Hang time. Analysis From my graph I can see that the predicted hang time and the actual hang time differ greatly from 293 Kelvin onwards, the real hang time increases quite dramatically where as the predicted hang time escalates only a bit. From doing this experiment I have found out that when pressure is increased by raising the temperature inside a squash ball, the particles gain more energy and can reform more quickly from its impact on the surface. My actual hang time results show this. My prediction was correct in the sense that my theory of the particles gaining energy worked. My predicted hang times unfortunately were not correct. They were not a good match to my actual hang time results; I put this down to another variable. The other variable I believe is elasticity of the squash ball’s material. I believe that if the ball has high elasticity then the deformation (formed by the impact of the ball hitting the surface) of the ball will be bigger and because it is bigger it will reform more quickly and bounce higher. The energy at the start of the ‘dropping’ process gravitational potential energy, but as the ball speed increases this changes to kinetic energy. When the ball reaches impact, kinetic energy changes to elastic potential energy and a bit of thermal and sound energy. This thermal and sound energy remain at a low constant throughout the rest of the balls ‘bounce back’. When the ball reforms it bounces up and gravitational energy increases to its previous level. Evaluation I think I conducted my experiment to a high standard and there were no major anomalous results (except the hang time and predicted hang time results). Each result had an average difference of 7. 9 between the next one, this average was brought down drastically by the 2. 8 difference between the first two results (38. 4 and 41. 2). If I were to make any improvements to the method and equipment of this experiment I would: – 1. Change the way the ball was dried as I think a more sophisticated way could be used to prevent human error. 2. Use a different way of timing the balls impact to the ground; a touch sensitive timer mat would work well. 3. I would try different surfaces on which the ball lands on, this could be thought of as another variable I could develop. If I were to do this experiment I would change the temperatures to smaller differences i. e. 273 Kelvin, 278 Kelvin etc. to see if I could find an ideal temperature that had a good enough ‘bounce’ to help develop work into elasticity of the balls material. If I were to develop this experiment further I would test elasticity. To test this I would experiment with a range of different squash balls. I would cut them into equal narrow pieces and use a Newton spring to test how much the piece of squash ball could hold and how long it would take to reform back to its original shape, for this I would use a Newton spring and stop clock. All in all I think I conducted myself well on this experiment and have learned a lot. Emma Dovaston 11GG Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

Time Management for Right-Brained

MANAGING TIME USING THE RIGHT BRAIN As we prepare ourselves to meet the challenges of the new century, we need to be concerned about the most critical of all resources, Time. As the pressure to become more competitive builds up, this resource is becoming more and more scarce. One can create and destroy any resource, but not time. However, the way time is managed differs from person to person. It is not how much time one has that is important. It is what do one does with one’s time. Most people have ambitions and aspirations in life. Every one wishes that he or she manages the goals in life successfully.But the critical issue is only a few succeed in reaching them in full. Why is that? There are different words to describe an outcome or an end result : ‘wish’, ‘desire’, ‘need’, ‘wants’, ‘goals’, are some of them. Of these, the word ‘goal’ presupposes a time frame and quantification and some efforts. B ut there is one more dimension to a goal in terms of its strength and intensity as understood by the mine. It is called ‘empowerment’. Empowerment is the process of giving an inner strength and wherewithal to reach the goal in spite of obstacles. It results in a mindset of restlessness and urge to reach the set goal.We need to look at the concept of time management from a different perspective. The process of what goes on in the mind is more important than what is exbibited outside a person in terms of setting priorities and pursuing various activities. To make a success of time management, it should be first be understood that it is a mind driven concept and not a system driven practice. To understand why some people manage time well, we should locate the seat of all our goals and aspiration in life. For this we should understand the working of the human brain.The human brain has two halves : the left and the right. The left brain is involved in language skills, it is analytical and it processes information in a linear fashion one after the other. It is logical and verbal. The right brain is the intuitive part of the brain, which is holistic and non-linear. This imaginative and creative part is responsible for the dreaming function. One this aspect of the brain is understood, it is easy to interpret what goes on in the mind of a successful person who manages his time effectively. In fact, there is no such thing as time management.The issue is self-management through pursuing an empowerment through emotional commitment. Any one who attaches a deep sense of emotion to the goal finds out a way of setting priorities to realise the same. He is able to withstand all the pains of initiating the controlling the various actions towards reaching his goal. For transferring the goal to the right brain, the visualisation skill of the right brain should be used. Before trying to manage one’s time, one should start with a powerful picture of the goal in his mind. One should visualise the goal with emotional attachment.It could all start with what others may dub it as a fantasy. After all, when you think about it, all inventions are a result of some one’s fantasies! 1 When the goal is powerfully represented in the mind through a bright picture of the future, the effect of the same involves the person so emotionally that it gets into his subconscious mind. The right brain alone can understand a person’s emotional attachment to his goal. When confronted with problems while reaching one’s goals, the left brain is logical and analytical and reasons out how it is impossible to reach the goal given the difficult circumstances.It reasons out how intense will be the problems to be surmounted, and, if allowed to prevail on the mine, will make the person to give up his goal. The way the right brain interprets the goal is different. It is not logical but intuitive. It is emotionally involved in the process of goal setting and will not give up. The right brain is not logical but creative and thinks about innovative ways of reaching the goal. It has already visualised the final scene of the goal achievement and hence ‘knows’ how nice it is to be in that situation of achievement and will not rest until newer and alternative methods of reaching the goal are found.A limiting belief makes you feel you are not capable of performing, as you want to due to some things present in the external system. Actually, limitation is not outside the person. It is within the mind. This is mainly due to the interpretation of the situation by the left brain, as it understands the situation. In such a situation, the right brain has to be used to get emotionally connected with the goal. This process will make the person believe in himself and his abilities to reach the goal. (Source : N. C. Sridharan’s article in The Hindu) 2 Related article: Â  Time Management

Bouns assignment Example | Topics and Well Written Essays - 250 words

Bouns - Assignment Example This can be due to not being aware of what is common knowledge and not knowing the range of works that must be cited, such as diagrams, charts, pictures, and other visual works (â€Å"Is It Plagiarism Yet?†). An example is when students think that a statement is common knowledge, when it is not because it is debatable or contestable (â€Å"Is It Plagiarism Yet?†). They engage in accidental plagiarism because they do not intend to copy any work and do not have the explicit will to make it look like they originally own it. Plagiarism is not worth the risk of being caught because it can lead to failed grades and even suspension. At the same time, it can impact the students’ credibility, especially his/her academic standing. It can ruin their image to academic institutions and the public. To prevent plagiarism, it is essential to know proper citation styles and to be sure to clarify when something belongs to other people’s works and when something belongs to one’s own ideas and

Unit 1 Micro Assignment Example | Topics and Well Written Essays - 500 words

Unit 1 Micro - Assignment Example This will occur in any sector of the economy, ranging from rent controlled houses, to basic needs supplies, and to luxurious human wants. For the duration of President Bush administration, the administration had levied price floors, which market analysts claimed were below the floor. In contrast, they did not produce price ceilings. As the economy operates, price floors alone have the propensity of gratifying the wealthy societal members, and captivating from the poor the petite they have, and at times, taking from the poor what they do not basically have to give (Mankiw 2011). Imposing price ceilings may create shortages, because it may discourage production, because manufacturers won’t be in a position to determine the profit margin they require from given products. It’s evident that price ceilings and price floors are inter-linked. For government efficient intervention in the economy, it should formulate a plan to impose both price ceilings and floors concurrently. By doing so, both the consumers and producers will be affected, but in a weighted manner such that the general societal members, especially those with low income reaps the benefits. Government involvement in the economy is way too far. Its fascination with safeguarding health, security and convenience has complicated the workings of the economy. For instance, the directive from government to have all pools in community centers and hotels fortified with lifts to guarantee easy access for the incapacitated has hiked the costs of these lifts to $8,000 to $20,000. This is not good for business, and has predisposed some community centers and hotels to close their pools completely. In another case, New York Mayor Michael Bloomberg has endeavored to ban the sale of soft drinks in servings with a capacity over 16 iotas. He proposes to levy the ban within all city eateries, and in other formations such as movie theatres and sports arenas.

Mark Twain used his writings to condemn hypocrisy because he feels Essay

Mark Twain used his writings to condemn hypocrisy because he feels that people should be able to tell the truth at all times.How - Essay Example In The Adventures of Huckleberry Finn, Huck’s last statement that, â€Å"But I reckon I got to light out for the territory ahead of the rest, because Aunt Sally she’s going to adopt me and sivilize me, and I can’t stand it. I been there before.† (Twain 569). Twain was trying to show the experience of Huck with Aunt Sally. Huck tries to explain that he has been enlightened before people of his age and this could be due to the fact that Huck started learning to be ‘sivilized’ at a tender age. ‘Territory’ in this context could be said to mean ‘the Indian territory’, hence, Huck’s first sentence could be said to mean that he had wanted to be independent before people of his age. Huck’s next statement that ‘because Aunt Sally she’s going to adopt me and sivilize me, and I can’t stand it. I been there before’ was used by Huck to kick against his adoption by Aunt Sally as he knows tha t Sally is someone that would try to instill some societal values and norms in him and he has had this experience before and this is something that he did not enjoy in any way. Huck’s experience with the Widow Douglas and Miss Watson were actually the ‘sivilizing’ experience he had as she tried to reform Huck and make sure that he conformed to the societal rules and order.

Argument essay about fast food Example | Topics and Well Written Essays - 750 words

Argument about fast food - Essay Example Behind them lies a simple explanation for why eating a hamburger can now make you seriously ill: There is shit in the meat.†    (Schlosser, p.196) No successful business, rather union, in this world would ever give away its most prized secrets in the name of benefit for humanity. Yet the consumers choose to ignore the bitter truth for a sweet taste. Their secret ingredients are full of not-so-secret health toxins that promote obesity, increased deposition of cholesterol promoting arteriosclerosis, hypertension, insulin resistance, diabetes and other fatal cardiac disorders. A more sedentary lifestyle contributes to an increase in these rates. An office job has you hooked to a desk and a chair with a flat Liquid Crystal Display right in front of your eyes. Which means a highly sedentary life style; this when triggered with intake of only fast foods can build up toxin pressure inside the body and slow atrophy. â€Å"The war on foodborne pathogens deserves the sort of national attention and resources that has been devoted to the war on drugs. Far more Americans are severely harmed every year by food poisoning than by illegal drug use. And the harms caused by food poisoning are usually inadvertent and unanticipated. People who smoke crack know the potential dangers; most people who eat hamburgers don’t. Eating in the United States should no longer be a form of high-risk behavior.† (Schlosser, p.264) Hundreds of thousands of dollars are spent each year in health care facilities, if a small portion of this percentage is allocated to restore health guaranteeing meat and other raw materials in the fast food or even if these fast foods are banned altogether a significant decline in mortality rate can be observed. Moreover consumption of fast food as a daily habit helps in generating a disabled world. Yes I completely agree

Network Access Using Correct Credentials Coursework - 1

Network Access Using Correct Credentials - Coursework Example Additionally, other abnormal computers like automatic dialing the internet may also be an indicator. Further, use of keyloggers can be essential in keeping a log of the number of times your account has been accessed. However, copying of small files may not increase network activity significantly so it may be hard to detect. Furthermore, shared folders are freely accessible on the network without the use of a password. The situation discussed above differs from packet sniffing. In it, there is no software required to access the folders as they are already shared and the password is also known. Additionally, packet sniffing is an illegal practice of intercepting network traffic to and from a computer on a network. The limit of what may be accessed through both of these methods is also different. While packet sniffing can access everything sent over the network, the above scenario does not include such capabilities. Using password to access a local computer is much easier than packet sniffing. The situation in question 2 is real and very likely in a work situation. Numerous cases of employees stealing information from their colleagues have been reported. One simple way for protection in such case is the change of password. Changing passwords constantly will ensure that someone has difficulty ever using your password to access your computer. Another method is by use of the firewall. A firewall may be a hardware or a software program which restricts unauthorized external access to a local machine or an internal network. Additionally, a review of which folders and files to share and which not to share is also important. The designers who had their systems attacked by a worm and their designs stolen would have known of this intrusion and subsequent theft of designs. An antivirus software installed on the computer is one sure way for such detection.  

Critical paper Essay Example | Topics and Well Written Essays - 750 words

Critical paper - Essay Example In his short story, Capote has successfully made me feel empathy with the protagonist of the story and his elder cousin, about whom the story is about, and around whose Christmas memories it revolves. Starting his reminiscing from late November in his past, the protagonist, who is referred to as â€Å"Buddy† in the story, relates how her older cousin, who is not named throughout the narrative, exclaims, as she does every year, â€Å"it’s fruitcake weather† (Capote 437). The older cousin is much, much older than Buddy himself, he is â€Å"seven; she is sixty-something† (Capote 437). Although it is never clear just who these two live with, however, it is clear that they live with their other relatives, as Buddy says â€Å"other people inhabit the house, relatives; and though they have power over us, and frequently make us cry, we are not, on the whole, too much aware of them† (Capote 437). This clearly means that both of them rely on each other and are friendlier towards each other than anyone else in the house, despite the extreme age difference. They like to do things together, and the older cousin has the tradition of making fruitcakes for various people before Christmas. They are poor, and though they want to buy a lot of things to bake the cakes, â€Å"there is the question of money. Neither of [them] has any† (Capote 438). Not much is provided to them by their relatives, and what they do have, they earn themselves by â€Å"holding rummage sales, selling buckets of handpicked berries, jars of home-made jam and apple jelly and peach preserves, rounding up flowers for funerals and weddings† (Capote 438). â€Å"But one way and another [they] do each year accumulate Christmas savings, a Fruitcake Fund† (Capote 438). Buddy reminisces about how they took pains to earn any penny they could, in any way possible, relating the story of how â€Å"[l]ast summer others in the house contracted to pay [them] a penny for every twenty-five flies

Efficiency tests Essay Example for Free

Efficiency tests Essay Day of the week test The day of the week efficiency test is the investigation of a particular stock market to see whether it reveals day of the week effect in volatility of returns, that is, whether stock returns in that particular stock market follow a certain pattern which is associated with what day of the week it is. Investing in the stock market is a wonderful way to make money, but it has a risk attached to it in the form of uncertainty. Stock market returns do not operate independently of the economic, political and technological environment of a country. In fact the stock market of a country is completely driven by the aforementioned environmental stimuli. However the relationship is indirect. Changes in these environmental stimuli do not directly affect the stock market. What they do directly affect is the investor mindset. The investor mindset in turn directly affects whether the stock market returns are likely to be good or bad. A bleak economic prospect for example will make the average investor wary of investing in assets. As a result he/she will stay away from investing in the stock market and as everyone, unsettled by the bleak economic prospect, follows suit, share prices, due to lack of demand, will drop drastically and, as returns hit the bottom, it will not make sense any more to invest in the stock market. In this manner, the stock market can behave very erratically as it is held hostage by hundreds of environmental stimuli the behavior of which few can predict to a certainly. This is why the day of the week test is important, because by applying it, the stock market investor can predict whether stock market returns on a particular day will be high or low. He can tweak his investment pattern accordingly. The stock market is highly volatile and it has been explained above what accounts for this volatility. As mentioned before, this volatility gives rise to substantial risks which give the investor second thoughts about investing in the stock market. However, this means that if the element of risk were to be eliminated to some extent, then that would make the stock market the original Aladin’s lamp as far as making money is concerned. Therefore every investor is always looking for ways to eliminate risk. The way the investor tries to eliminate risk to some extent, or to minimize it, is to find a way to predict what the return of a particular stock is likely to be at a certain point of time. That is why we, as the investors, use the day of the week. If we are investing in the US equity market for example, then we apply the test to find out whether the market has a presence of the day of the week effect in it. If so, we invest only on those days on which the return of the stock we are investing in is likely to be high. In other words, we use the day of the week test to maximize the returns and minimize the risks of our portfolio. The question as to whether we benefit from this test has already been answered. We most certainly do as otherwise we wouldn’t be able to predict how the market is going to behave on certain days and as a result our investment decisions would be very risky indeed. So we do benefit from applying the day of the week test. But how do we benefit from it? We benefit from it because the day of the week test allows us to detect whether there is an element of seasonality in stock returns of our portfolio. As soon as we have detected seasonality, that is, returns are high or low depending what time period it is, we have immediately minimized the investment risk. An equity market for example which boasts the presence of the day of the week effect in it will tell us that returns on Mondays will be significantly lower than they are on other days of the week. Under the circumstances, the decision as when to buy stock and when to sell is not so difficult any more. In the aforementioned equity market, we should obviously stay away from making any stock purchases on any other day than Monday because the day of the week test that we have applied to the market tells us that prices will be lowest on Mondays. Therefore, to minimize expenses, we should buy stock on Mondays. By the same reasoning, when the time comes to unload the portfolio, we should obviously do the selling on any day of the week other than Monday, because in the six days other than Monday, prices will be higher, which translate into higher returns for us investors. So clearly the benefits from applying the day of the week test are substantial. They all center around the ability of the day of the week test to introduce an element of regularity into the midst of what on first sight seems unconquerable chaos. This test tells us there is a day of the week regularity functioning in the equity market and that if we invest accordingly, we shall have maximized our returns and minimized the associated risks. End of month test This is a test that seeks to establish the presence of a calendar anomaly in the behavior of stock market returns whereby returns are higher over a time period beginning with the last trading day of the current month and continuing over the first five days of the next month. The importance of this test is in taking advantage of the fact that stock returns are not completely volatile, that they do have a certain pattern hidden deep under the apparently wildly fluctuating numbers. This directly contradicts the efficient market hypothesis which states that any information, whether public and private, that is available to the investors, has already been taken into account in stock pricing, therefore no single investor is in a position to take advantage of the market. According to the efficient market hypothesis, risk is the same for all investors. However it has been recently discovered that there is a end-of-month or turn-of-the-month effect when stock returns are shown to be consistently higher on the last trading day of a month and over the first five days of the following month. This probably happens because during this time period the general level of liquidity goes up as a result of settling liabilities so that the investor has more cash with which to play around in the stock market. As has been mentioned before, the performance of the stock market is a direct function of the general mindset of the investing public. If the investing public are in a good mood, then the market will perform well. If they are in a bad mood, the market will perform badly. These mood swings on the part of the general investor are a direct function of the macroeconomic news items which they are exposed to though the different media. Therefore the timing of the release of these macroeconomic news items is an important factor in determining how the stock market will perform afterwards. Usually these news items are released during the first few days of a particular month. Stock market returns have been shown to maintain an upbeat trend as time approaches the scheduled release of macroeconomic news. That is why end-of-month testing is important because it shows the existence of calendar anomalies in stock returns brought about by scheduled release of macroeconomic news items. That is also the reason why we use this test. By using this test, we can detect the presence of calendar anomalies in the stock in which we are investing and take advantage of it to make capital gains. By using this test, we prove that the efficient market hypothesis is by no means the last word in the world of finance, that the risk inherent in investing in a particular stock is by no means the same and a test that gives us the ability to predict risk is a worthwhile exercise by any standards. As can be seen from above, we can benefit from the day of the month effect. The benefit to be gained from this test is inarguable inasmuch as we have the ability to minimize systematic risk inherent in any investment decision. According to the risk-return relationship, the risk in investing in a particular stock has two components. One is the unsystematic risk and the other is the systematic risk. Investors do not worry about the unsystematic part as it can be eliminated by means of diversification. Investors put their money in a wide variety of financial instruments so that even if one company is performing not so well thus dragging down its share performance as well, there are other companies in which the same investor holds shares and which is performing well thus canceling the negative effect of the under-performing company. It is highly improbable that all the companies will be underperforming at the same time. What is more probable is that one will outperform the other thus eliminating the unsystematic risk. However it is well nigh impossible to eliminate or to even reduce the systematic risk which affects entire market to the same extent so that no amount of diversification will cushion the effect of a high systematic risk. However that is according to the traditional finance theory. According to the new theory whereby there is a end of the month effect in every stock market, systematic risk is definitely lower in the last trading day of the month and in the first few days of the next month. So the benefit we get from this test is that we can predict a little better how the systematic risk is likely to be at what point in time in the month. Moving average As has been mentioned before, stock prices can fluctuate significantly over a certain period of time. If these prices are charted on a graph, then the trend line will zigzag substantially, making it difficult for us to evaluate whether a particular stock is underperforming or otherwise. Moving average is a technical analysis tool which allows us to smooth out these fluctuations, so that there is a consistent trend line which can serve as benchmark for the evaluation of stock performance. Moving average is a very important technical analysis tool. Inasmuch as it enables us to impose order upon chaos by creating a consistent trend of the performance of a particular stock, its importance can hardly be overemphasized. If the returns of a particular stock were to be presented in the form of a scatter plot, then on first sight it would appear as white noise. It would be impossible to make head or tail of this extremely chaotic scatter plot. However if one were to apply the moving average technical analysis tool, the widely scattered points would give in to a rising or declining trend line which could then indicate whether a particular stock is performing below that trend line or above. In this respect, moving average is a very important indicator of stock market returns. Before we make any investment decisions in respect of the stock market, it is obviously important for us to find out which stocks are performing above expectations and which stocks are performing below. Moving average allows us to make that determination and that is why we use this tool. The problem that every stock market investor faces is that the returns on the face of it seem to be impossible to predict. Charted on a scatter plot, as mentioned before, the returns are all over the place. That would not be the case however once we apply the moving average tool to these returns. Once the moving average technical analysis has been applied, it would appear that the returns conform to a predictably progressing trend line. And that is why we use the moving average technical analysis, to introduce an element of predictability into an area which would otherwise seem impossible to predict in any way. We certainly benefit from using the moving average analysis as it allows us to determine whether a stock at a particular point of time is performing below the trend line or above. This would enable us to determine when to buy and sell. When to buy and sell is the toughest decision that a stock market investor faces. Obviously an investor would like to buy a stock when the price is at its lowest and would like to sell when the price at its highest. But how does an investor know when the price has bottomed out so that he should buy and when it has topped out so that she should sell? These points the investor must determine and the benefit of using the moving average technical analysis lies in the fact that it allows the investor to determine those points. An additional benefit of the moving average analysis is that it can be calculated both short-term and long-term. A short term moving average can be defined as a 15-day moving average while a long-term moving average can be defined as a 50-day moving average. Thus there are two trend lines and when the short-term trend line moves below the long-term, the stock is on a downward momentum and it is time to sell. Conversely, when the short-term trend line is passing above the long-term, the stock is on an upward momentum and it is time to buy. In this way the moving average technical analysis allows the investor to decide when to buy and when to sell a particular stock. Correlation Correlation allows us to test whether there is any relationship between two variables and if there is a relationship, whether the relationship is positive or it is negative. For example, a correlation of +1 indicates a positive relationship exists between two variables. A correlation of -1 indicates that the relationship between two variables is negative. When the relationship is positive, it indicates that the two variables move in the same direction and when the relationship is negative, it indicates that the two variables move in opposite directions. Correlation is an important indicator of the future behavior of a particular variable in relation to another variable. It allows us to determine what other variables affect the performance of the variable of interest and to what extent. Once we have correlation figures quantifying the relationship between the variable of interest and other variables, we can predict how the variable of interest will change when the other related variables change. Inasmuch as correlation allows us to reduce uncertainty by enabling us to enhance predictability, it is an important indicator. We use it for example when we are trying to decide whether or not to invest in a particular stock market. As has been mentioned before, the performance of a stock market is affected by a wide variety of factors. The most prominent environmental stimuli are the economic, sociological, political and technological changes taking place both nationally and internationally. It is important to know therefore to what extent these stimuli affect the performance of a particular stock market. Correlation allows us to determine that extent. By applying correlation, we can find out how a certain change in the economy is likely to affect the stock market performance of that country. We come to know about these changes in the form of microeconomic news items which can be categorized based on their content. If we already have the correlation figures for these categories of news items, then as soon as they are announced, we can reasonably expect to be able to apply the correlation statistics to assess how the news items are likely to affect the performance of the stock market we are interested in. This reduces risk to a substantial extent. Risk reduction is the most important consideration in the mind of an investor. For this reason, we use the correlation statistic. We do benefit from the use of correlation inasmuch as it gives us a window into the future regarding the performance of particular stock market. An example of a benefit would be an US investor considering investing in one of the Arab stock markets. In assessing whether it would be a good idea or not to go ahead with the investment, the investor would find use of correlation of immense value. The investor would have to collect a great deal of knowledge connected to the economic, sociological, political and technological scenarios of the Arab country and determine by means of correlation how the different environmental factors are correlated to the portfolio performance in that stock market. Once that is done, he or she would be in a position to foresee how the different changes in the Arab country would affect the performance of the stock market in that country. This would enable the investor to buy and sell at the right time. As has been mentioned before, there are also international forces at work which will affect stock market performance in the Arab country. In this respect, what the investor can do is to run correlation tests between the Arab stock market and the US stock market to see how the two markets are related. In this respect, the two markets would be two variables which the correlation test will examine to find out whether any relationship exists between the two variables and if so, if the relationship is positive or whether it is negative. If the relationship is a positive one, then whenever the US market is performing well, the Arab market can also be expected to perform well and vice versa. Clearly this is of immense value to the investor as it allows him to pick the time as to when he should invest in the Arab stock market. That is the benefit. Descriptive Statistics So far the discussion has focused on predicting the future performance of the stock market. Now it’s time to focus on assessing the current performance of the stock market. That is what the descriptive statistics are for. Descriptive statistics such as the mean and the standard deviation and the normal distribution help us evaluate the existing performance of a particular stock market. Descriptive statistics are very important because they quantify the performance of the stock market. The most widely used descriptive statistic is the mean. We can calculate the mean stock return by calculating the average of several stock returns from past time periods. This tells us the return we are likely to get if we invest in that stock. However the mean does not take into account the risk that comes associated with investing in stock. As has been mentioned before, the stock market is a wonderful way to make money but every rose has it thorn and that thorn in this case is the risk. Stock returns are affected by so many variables both internal and external to the company that it is impossible to take into account all of them. This is where risk springs from. Because there are so many forces at work playing sixes and sevens with stock market returns, wild fluctuations are a necessary evil for the stock market investor. However even here, descriptive statistics can help by introducing order into chaos. The descriptive statistic in question is the standard deviation. Because stock returns fluctuate extensively, they are scarcely at the mean. Sometimes they are above the mean and sometimes they are below. Standard deviation tells us the percentage of returns which will deviate from the mean to a certain extent. Most stock returns conform to the normal distribution, that is, most of the returns are clustered around the mean return. 66% of the observations fall within one standard deviation away from the mean. 95% of the observations fall within two standard deviations away from the mean. And 99% of the observations fall within three standard deviations away from the mean. Inasmuch as stock market returns, given a sufficiently large sample size, follow the normal distribution, descriptive statistics are very important as they enable the formation of the normal distribution. This facilitates investment decisions. Descriptive statistics also come into play when determining the risk-return relationship. Risk is a prime consideration in any investor’s mindset. Investment in the stock market is meaningless unless a way can be found to minimize the influence of risk. To complicate matters further, there are two categories of risk: systematic risk and unsystematic risk. There is hardly anything the investor can do about the systematic risk. It affects all the stocks present to an equal extent. An example of a systematic risk is when there is a sudden political eruption. The political turmoil will have a negative effect in all areas of the business sector. Therefore even if the investor is holding a portfolio of stocks, it will be of little avail. The other element of risk however, the unsystematic risk, is more manageable. It means not putting all eggs in one basket. Managing a portfolio of stocks is key to eliminating or reducing unsystematic risk. An investor who has invested in a portfolio of stocks will reap more than an investor who has invested in only one stock. This is for the simple reason that external environmental stimuli do not hit all industries of the business sector to the same extent. If there is a technological change for example, some industries will benefit more and some less. Therefore the wise investor will invest in those industries which benefit more as a result of the technological change. Alongside the technological change, there will be other changes, economic or political or sociological, which will have a negative impact on some of the industries. As a result the stock returns in those industries will take a nosedive. However an investor who is maintaining a portfolio of a wide variety of stocks will not be hit adversely as he will have stocks in that portfolio of his which were immune to the economic or political or sociological change in question. In this manner the unsystematic part of the risk has been eliminated. The stocks present in a portfolio will be negatively correlated. That is, if one stock goes down in terms of returns, then another will go up. Thus the investor is well protected. However he is by no means protected from the systematic risk which no amount of diversification can eliminate. However all is not lost because descriptive statistics are there to help the investor. He already knows from the central limit theorem that most stock returns conform to the normal distribution. Once that is known, the investor can make an accurate prediction as to where the stock returns are likely to fall. This substantially reduces systematic risk. As mentioned before, there are some exceptions in terms of stock market returns which do not strictly follow the normal distribution pattern. These returns follow a different probability distribution. The use of kurtosis and skewness can help to identify that particular category of probability distribution. Determining which probability distribution a particular stock market conforms to, in which the use of descriptive statistics is key, is vital for picking the optimum portfolio. An investor would obviously want to invest in only those stocks the returns of which stick most closely to the mean. What the investor can do is to collect the percentage returns of a stock for a number of time periods and calculate the mean and standard deviation of these percentages to find out whether that stock shows a high volatility or a low volatility. The intelligent investor will obviously want to pick those stocks which have low volatility because their returns will be more predictable. So what descriptive statistics are very good at making sense of historical information to the immense benefit to the investor. As has been discussed so far, the historical returns examined without the benefit of descriptive statistics will not generate a lot of information. To the naked eye, stock returns on a historical basis reveal no pattern. There is no discernible trend. Viewed through the lens of descriptive statistics however, stock market returns suddenly become very orderly and systematic. Now the investor knows which stocks to embrace and which stocks to keep away from. Now the investor knows what the optimum portfolio will be which will take into account both systematic risk and unsystematic risk and generate the highest returns.

Analyze The Impact Of Facebook For Student Media Essay

Analyze The Impact Of Facebook For Student Media Essay After 2 years of launching, Facebook has accumulated millions of users. Through Facebook the users can edit their profile, sending message to friends, chat, play games and other features are also available. Due to this fact Alexa.com has ranked Facebook 2nd most widely used social site. This is also proclaimed by Mark Zuckerberg open letter, now Facebook has over 350million users worldwide. All of those data show that Facebook nowadays has become part of the students life. The student needs to interact with their friend or family. Furthermore, Facebook has became an alternative for email. One of the differences between Facebook and email, Facebook can show you the update about your friends. You can also view your friends latest activities and give comments. Online games that provided in Facebook also make us access Facebook more often. All these possibilities can lead to Facebook addiction and can make student life become imbalance, then it will affect the academic performance. For example, the students become less concentrated in the class if the class has computer that connected to the internet. 1.2 Statement of The Problem Logged into Facebook account during teaching or learning session. This action can be observed in classroom equipped with the computer and internet access. During the class most of the students are not paying attention and rather prefer to surf on internet and login to their Facebook account. This behavior signals addiction and it will jeopardize their academic performance. Social website like Facebook is very famous among the student and some of them are getting addicted. As a student, our nature is to interact with other people. We need other people in our lives. Facebook satisfy this human need. At Facebook you can communicate your opinion, share pictures, videos and give comment on friends profile. Besides that, at Facebook you can also create an invitation to spread news about any events and invite them. This is a sign of addiction which could be happening, when you login to Facebook, it distracts your time when you are supposed study, the inability to control time spent on Facebook. 1.3 Objective Our research on Facebook effects among the Hamdard university, which narrows our research focusing on the students in their academic activities. Our main focuses are: To inform the readers about the advantages and disadvantages of the Facebook. To analyze the impact of the Facebook on students. To suggest ways of minimizing the bad impact of Facebook to students. 1.4 Significance of Study After conducting the research about the effect, we hope that we can contribute something to the student or the reader that have problem what we have explained in the problem statement. The main purpose it to relate our study to the problem and suggest solution about it. Our significance of studies are: Finding will analyze the impact of Facebook for student. Solution will help student to improve their academic performance. 1.5 Scope To help us make the research possible with the given time and resources, we need to limit our scope. Furthermore, we decide that our subjects to gather the data are only limited to Hamdard University students. 1.6 Research Question Based on our research objective, we are going to conduct research to answer several research questions that can help us answer the objective. The questions are: What are the advantages and disadvantages of Facebook? What are the impacts of Facebook to the student? What are the solutions for the student to minimize the negative impact to Facebook? CHAPTER 2 LITERATURE REVIEW 2.1 Overview This chapter discusses the impact Facebook has on the campus. But, first lets see how far Facebook has developed beyond campuses. There are a lot of facts that can show how far it has gone, eg, According to Fodeman and Monroe (article January 12th, 2009) says that four years ago it was rare to learn of a child under 7th grade with an account. Last fall, for the first time, 4th graders began reporting to us that they had Facebook accounts. Now, in the light of this statement we have found out that 60 70% of 7th graders have accounts and the number is higher for 8th graders. These children are too young to be using Facebook or other adult social networks for the reasons. Regarding the impact of Facebook, which is the main problem will be discussed later on in the report. In this chapter the impact of facebook will be divided into two parts, first the advantages of facebook and the second the disadvantages especially for the students of Hamdard university who are our main research targ et. 2.2 Advantages of Facebook Social network sites such as such as Facebook allow individuals to present themselves, and establish or maintain connections with others. These sites can be oriented towards work-related contexts, romantic relationship initiation, connecting those with shared interests such as music or politics, or the college student population. Participants may use the sites to interact with people they already know offline or to meet new people. Facebook enables its users to find friends who can post comments on each others pages, and view each others profiles. Facebook members can also join virtual groups based on common interests, to see what interest do they share with others, and learn each others hobbies, interests, musical tastes, and romantic relationship status through the profiles (Ellison et al, 2007). Facebook comprises of a rich site for researchers interested in the affordances of social networks due to its heavy usage patterns and technological capabilities that bridge online and offline connections. Previous research suggests that Facebook users engage in searching for people with whom they have an offline connection more than they browse for complete strangers to meet (Lampe, Ellison, Steinfield, 2006). 2.3 Disadvantages of Facebook Facebook has became famous, it is because that it allows people who probably have never met in a real world can have a good communication with each other and built a new relationship and friendship, also from Facebook people can post anything they feel in short term and may get many attention from their friend that make that personal feel more comfortable because there many friend care about his personality. Facebook make our society very open, people have their right when they want be friend from their profile so there many user put many things in their profile that can make other people interest on their profile.(J. Cooper, 2008). Many academic institutions around the country especially Hamdard university have felt the changes of students only from a social network their use especially Facebook. However, this new technology also brings negative implications, such as lowered GPAs etc. Without realizing that everything they post to Facebook they actually is not privacy anymore even that become a serious criminal offence if they are not aware about what they post in internet. For example the administrator at Purdue University, Pablo Malavenda came across Facebook page and he found there is one group called We Hate Pablo and that posted his home address and instruction to eliminate him (J. Olson, M. Clough and K. Penning, 2009 p. 445). Scam can be done by sell a product through the internet and post the link in Facebook, when someone interested and buy the product the payment for that product is through credit card or pay pal. Finally, when the buyer already pays for that product, he or she does not get the product because that product actually not really exists. CRITIQUES OF SOCIAL NETWORKING IN EDUCATIONAL INSTITUTES The unpredictable damaging effect of Facebook and other social sites have been long debated within the boundaries of academic strongholds and outside, a new concept of Cyber bullying has emerge for many institutes, especially since 2000. Several studies are made especially a recent article in the Illinois School Board Journal suggests that girls in particular are victimized to cyber bullying and are being harassed. The truth is that Cyber bullying exists in or out of the educational institute boundaries, its up to the institute teachers and parents of students to understand this problem and deal with it. The more dangerous problem is that students today see the web as their private playground and are unaware of the dangers posed by careless online postings. Using Facebook takes time. Often, a LOT of time! Greatest factor for individuals is to socialize and the passion to socialize is increasing. Their irresistible need to connect with their peers, joined with the development of 24/7 accessible technologies, can make the use of sites like Facebook irresistible. Socializing might be necessary but intensive use of these social sites may lead to unstoppable use. This will take away the allocated time from other activities i.e. studies,work,sports etc THE EFFECTS OF SOCIAL NETWORKS ON AN INDIVIDUALS PERFORMANCE The social network approach holds that the behavior of an individual is effected by the relationships and the technology that he might posses rather than the norms he practices. The social feelings exchanged between two individuals characterizes their tie. Social networks have a positive and a negative effect on the individuals performance, these effects can be on studies,work,family etc. Researchers have found that positive network does have a positive effect on work and academics, on the other hand, the effects of an negative network are negatively related to performance. It is imperative to talk about three social networks on students performance. A. Friendship Networks Friendship between two people can emerge only if and when their paths cross. They would be more likely to meet and share. This fairly does not means that it only determines that individuals will only meet but also influence other factors such as visibility and closeness. Increased visibility and exposure increase the likelihood of becoming friends. Therefore, a student who is in to a friendship network has more opportunities to access resources that may be important to successful academic performance. Perhaps it is the most importantly resource for a student in coping with academic related stresses. A student who is central in a friendship network has a greater chance of helping others and also being helped; thus, he is likely to perform better in the instructional setting, and so people who are central in friendship network are likely to be popular in web-based forum, and may have a better chance in developing more friendship with others. This will lead to a larger social circle, increasing in social popularity which may also gather individuals who can help with academics activities thus having a constructive effect on our academic activities. B. Advice Networks Advice networks are such networks through which students can share resources eg. Information, assictance,guidance which are related to their work. The advice network is more practical than friendship network. Advice network works in a way, when an individual is given a task he may turn towards to these networks and obtain available exchange of resources, guidance and information. When the job is done the person can now provide the resources obtained to others in order to guide them. A person who is a part of advice networks is likely to perform better in class because he possesses task-related information, experience and guidance. Thus advice networks are positively related to the performance of an individual in a academic setting. C. Adversarial Networks Adversarial relations refer to those relations that may involve negative exchanges. Those kinds of relations cause emotional distress, anger, or unresponsiveness. They have been found to have a drastic effect on the students performance and satisfaction, thus it is negatively related to performance. Such networks are responsible for diminishing concentration in students, lack of attention and an outcast. Deep analysis shows that individuals who are a part of such networks will have a hard time keeping up with performance, as referred in the beginning the friendship network is to make friends who will be a use in time of need and will demonstrate a positive relationship, but what if due to adversarial network you might indulge in a relationship that might take you to a spiral down life. Studies have shown that many single individuals use social networks to get involved in a relationship that at times lead to a disastrous result in the end. The person involved in such relation sufferin g a setback will experience emotional turmoil, anger, hatred. Another example of adversarial network is that many users dont care what are they getting involved in online, they also get caught in criminal activities that will put their life to a halt. Being a part of an Adversarial network will lead to misfortune that will force the individual to pay a great price. Does social networking hurt student grades? The explosion is stunting students language skills , this article was posted by Kate Conrath, she herself was a facebook user, she started using Facebook in college , made progress while using it upto the level of completing college and moving on, she learned many progressive things such as writing personal statement, term papers, refined her oral language, working with master interviews etc., clearly she was a part of a friends network or advice network which have been discussed above. She got a job as a teacher, she found out that students using facebook had a different approach that she used to have when she was using facebok at her time. Today, many students are using Facebook, Twitter and other social networking sites, sometimes hundreds of times a day. Their growth in vocabulary becomes stunted because of the social networking explosion, they practically use the words like ill c u l8er or I ll cum to ye hum 2day, students using social sites extensively and usually chatting will use these words in their conversation and will have a adverse effect on their real vocabulary when theyll interact with others. Perusing social networking sites has the same effects as watching too much television; its a major distraction with no possible benefit. Preoccupation with these sites has completely taken over as the major chunk in students life free time. Just like adults put away their responsibilities (grading papers; perhaps?), students avoiding homework and not completing their tasks which will lead them to a spiral downwards. CHAPTER 3 RESEARCH METHODOLOGY 3.1 Introduction This section discusses the methodology of the research. The main purpose of the research is to give solutions to help student reduce their addiction in social network, Facebook. To get some information why they become addict with Facebook, we will chose a smple size of 50-100 students around the campus. Data for the research will be collected through questionnaire and observation. 3.2 Target area of research We will be targeting students of our department with a sample size of 50-100 students ranging from BBA Freshman to MBA finalist. 3.3 Research Instruments This research utilized both quantitative and qualitative research methodology. The instruments used to collect the data were questionnaire and observation. A set of questionnaire will contain 14 questions including space for comment / opinion / suggestion on the topic. The qualitative data for the research come from observation, and find for another data from internet. For example from internet, we find from Wikipedia, and various other sites that can help us to get some information for this research. 3.4 Data Analysis To process the data, the questionnaire and observation data both will be separated into two groups, which will be addicted and non-addicted group. The data will process and enter to the computer using Microsoft office Word software and process the data into the graphs and charts, and then the explanation and description about the result will be included in the document. Abstract Facebook has over 350million users worldwide data show that Face book nowadays has become part of the students life. it has became an alternative for email,games,file sharing etc.Facebook addiction and can make student life become imbalance, then it will affect the academic performance. Analysis of the research will reveal how much and many students are addicted to facebook and how many are suffering depleting grades and are unable to fulfill their academic goals. The research method which will be used in this research will be both quantitative and qualitative, we will taret the students of Hamdard University with a sample size of 50-100 students undergraduate and masters. This data will be analyzed and will be broken down in to two parts i.e. addicted and non addicted people, in the end we will provide a solution how these addictions can be overcome and academic goals can be achieve.

Microstructure-mechanical Property Relationships

Microstructure-mechanical Property Relationships Microstructure-mechanical property relationships in high strength low alloy steels for automotive applications Chapter 1 Introduction The production of steel is an ancient process which has evolved over time. Where and when Steel was first created is unknown and a topic of much debate, however most historians believe earliest production of steel originates from China from as early as 202BC. A later form of steel named Wootz Steel was later developed in India, which used wind power to fuel a furnace producing nearly pure steel. In the 11th century China developed steel further was the first country to mass produce steel. Two methods were developed. A berganesque method which produced inhomogeneous steel, and a process which that relied on partial decarbonisation through repeated forging under a cold blast, this was seen as the superior method, and one which lead on to the Bessemer process [1].The Bessemer process involved using a blast furnace to extract iron from its ore and is the basis of modern steel extraction. Steel is produced firstly by extracting iron from its ore. Iron extraction differs slightly from other metals as it can only be found naturally in oxide form. This means that a smelting process is required. This involves a reduction reaction followed by alloying with additional elements like carbon to stabilise and strengthen the steel. Iron smelting requires a high temperature which produces a ferrous material made of a combination of iron and steel. The addition of alloying elements such as carbon affect the materials properties greatly. Changing the temperature at which the iron is smelted affects the phase of the resultant steel, giving rise to the possibility of producing steels with varying properties which are suitable for a range of applications. In the automotive industry, body frames were originally made of hardwood. This was replaced in 1923 when the American Rolling Company developed steel sheet production. The wooden frames were inferior in energy absorption which was a big safety issue. Steel was also much easier to form than wood and did not warp over time. As the automobile has evolved over time, there has been an increasing public awareness of the environmental impact of the car. This has forced manufacturers to produce lighter cars which are more economical. This brought about the development of thin, highly formable sheet steel. The main competitor to steel in the automotive industry is Aluminium, which offers a much better strength to weight ratio and also a better resistance to corrosion. However steel is still the most commonly used material mainly due to lower production cost. Increasing competition from aluminium is forcing the development of modern steels. Steel naturally has a higher formability and elongation than aluminium which is one of the reasons it is used so extensively in the automotive sector. This can be seen in Figure 1.1: Figure 1.1- Yield strength vs total elongation of aluminium alloys and automotive steels [3] Ultra low carbon (ULC) steels are used commonly in the production of automobiles. Their, highy formability and suitability for hot dip galvanising make them very attractive to automobile producers[4]. Pressure is being put on the manufacturers to produce lightweight cars that minimise emissions without compromising safety. Metallic properties required to achieve this consist of a high tensile strength, high r- value, good ductility and also the ability to be made resistant to corrosion (either naturally or through the use of chemical surface treatment). Various high performance steels have been developed to meet these requirements, of these, one of the most important being HSLA steels. High strength low alloy steels provide a much better strength to weight ratio than conventional low carbon steels allowing for thinner grades to be used, saving weight. HSLA steels have a manganese content of up to 1.5%, as well as microalloying elements such as vanadium and titanium. HSLA steels are increasingly replacing traditional low carbon steels for many automotive parts. This is due to their ability to reduce weight without compromising strength and dent resistance. Typical applications include door-intrusion beams, chassis members, reinforcing and mounting brackets, steering and suspension parts, bumpers, and wheels [5]. High strength low alloy steel properties are determined by the way in which they are processed. High deep drawability, can be achieved through precipitation of elements by annealing to produce a strong {111} recrystallisation texture [7], producing highly formable steels which are very desirable for automotive applications. In this study, two grades of IFHS strips are studied. A titanium only stabilised steel grade and a titanium-vanadium stabilised steel grade. These have been treated using a Viking tube furnace and studied using a scanning electron microscope, Photoshop and Optilab Software. Both steel grades have been studied using carefully selected thermo mechanical heat treatment cycles. The heating variables are expected to cause varying effects to the mechanical properties and microstructure of the two materials. The addition of vanadium in one of the steel grades is also expected to influence the mechanical properties. With the data obtained from my experiments I hope to determine the optimum processing route for similar HSLA steels. Chapter 2 Aims Carry out selective batch annealing heat treatments on two microalloyed High Strength IF strip steels. Measure grain size evolution samples using scanning electron microscopy and quantitave optical microscopy techniques. Measure mechanical properties of obtained samples using hardness and tensile testing techniques Determine the optimum processing characteristics, resulting in optimum mechanical property characteristics. Chapter 3 Literature Review 3.1 AUTOMOTIVE STEELS Automotive manufacturers make use of many different metals in the production of cars, of which the most predominant being steel. This is for several reasons, steel is relatively easy to recycle in comparison with polymers and aluminium, and this is an issue which is growing in importance as the public are becoming more and more environmentally aware. Steel is also a very good material in terms of its practicality, as it is easily welded, has good formability, elongation and ductility. As the environmental impact of cars is becoming more and more important, stringent regulations regarding emissions are being forced upon manufacturers. One of the ways that manufacturers have chosen to meet these requirements is to make the cars lighter by switching from mild steel to high strength steel grades which enables components to have a thinner cross section, saving weight. The three main types of steels used in automobiles today are; Low strength (IF and mild steels), High strength (Carbon manganese, bake hardening, IFHS and HSLA) Advanced high strength steels (dual-phase, complex phase, transformation induced plasticity and matensitic steels) These steel types can be seen below on figure 3.1 comparing their elongation and strength. Figure 3.1: Classification of automotive steels [8]. 3.1.1 Mild Steels Mild steels are normally found in two different forms for automotive purposes. Drawn Quality and Aluminium killed. These are both cheap to manufacture are used for high volume parts. They are usually of a ferrite microstructure. [8] 3.1.2 Interstitial Free Steels IF steels are used for car body panels extensively due largely to their deep drawability. The high elongation achieved in comparison with other steel grades can be seen in figure 3.1.The main characteristic of IF steel is a low carbon and nitrogen content. These elements are removed from solution by adding specific elements for alloys. Commonly used elements for this microalloying process include Manganese, Sulphur, Titanium and Niobium. As well as a deep drawability, IF steel have low yield strength but a poor dent resistance which is undesirable for certain automotive applications [6] Bake Hardening Steels BH steels keep carbon in solution either during processing before it is precipitated or during the paint baking state [8]. This strengthens the steel through solid solution strengthening, resulting in steel with both high formability and high strength. 3.1.4 Carbon-Manganese Steels Carbon-manganese steels are solid solution strengthened and are used in strip form on automobile bodies, although they are becoming replaced by lighter steel grades. They offer high drawability and are relatively cheap to produce. [9] D.T.Llewellyn: Steel: Metallurgy and Applications, Butterworth-Heinemann Ltd, Great Britain, 1992. 3.1.5 High-Strength Low-Alloy (HSLA) Steels HSLA steels are strengthened through the addition of microallying elements. These react with the carbon and nitrogen within the steel to form carbides and nitrides. Common elements include Nb, V and Ti. The resultant steel has both high strength and a high formability due to very fine grain sizes [10] Dual-Phase (DP) Steels Dual-phase steels contain two phases within their microstructure. These are ferrite and martensite. This two phase structure is produced through a complex series of contolled heating and cooling. Martensite regions are produced by heating and rapidly cooling. It is the marteniste regions tha give the hardness to the material where as the ferrite regions are much softer. The structure of DP steels takes advantages of the properties of each of the phases, where the hard maternsite regions are surrounded by softer ferrite which reduces brittleness, shown in figure 3.2. DP steel has good ductility, low yield strength but high work hardening rate [8]. Figure 3.2: Microstructure of DP steel [8]. 3.1.7 Transformation-Induced Plasticity (TRIP) Steels TRIP steels consist of a mainly ferrite microstructure with a low austenite content within the matrix. An isothermal hold during production at an intermediate temperature is used to produce bainite [8]. Strength is increased by transformationing of austenite regions to harder martensite regions. TRIP steels have a good work hardening rate and good strength. Work hardening in TRIP steels continues at higher strain levels than those of DP steels so TRIP steels is a superior material from this aspect. Figure 3.3 shows the multi phase microstructure of TRIP steel. Figure 3.3: Microstructure of TRIP steel [8]. Martensitic (MS) Steel MS steels are mainly of a martensitic microstructure but contain small amounts of ferrite and bainite. During heat treatment the steel is rapidly cooled transforming austenite into martensite. This gives a very high tensile strength since martensite produces a very hard material, but the drawback is this also gives a low formability. In order to overcome this low formability further processing such as heat treatments must be undertaken. [11] 3.1.9 High Strength Interstitial Free (HS-IF) Steels HSIF steels are strengthened through the addition of microalloying elements. Commonly used alloying elements include P, B, Si, Mn, Ti, N. The combinations in which the microalloying elements are used have an effect on the properties of resultant steel allowing a range of requirements to be met. HSIF steels can produce nearly twice the potential yield strength as conventional IF steels, although there is a reduction in formability. 3.2 Microalloying Elements 3.2.1 Carbon Carbon is one of the most important interstitial elements within steel, giving very different mechanical properties as its percentage content is altered and therefore must be studied in depth. Carbon is an element commonly found in automotive steels due to its high strength properties. Although adding carbon increases strength, it also affects the formability, i.e. its deep drawability. A set of experiments were carried out to determine the effect of carbon content within steel. When analysing the tensile test results it was noted that the ultimate tensile strength, the proof stress and the yield stress all increased as the amount of carbon increased in the steel. The plastic region as well as the general elongation of the steel under tensile stress decreased as the carbon content increased. These are significant changes in the mechanical properties. Hardness and Tensile strength increase as carbon content approaches 0.85% C as shown in figure 3.4. The elongation percentage decreases as the carbon content increases. This suggests that the more carbon present in the material, the stronger and less ductile it becomes. Figure 3.4: Affect of Carbon content in Steel Yield Strength Carbon content influences the yield strength of steel because carbon molecules fit into the interstitial crystal lattice sites of the body-centred cubic arrangement of the iron molecules. The interstitial carbons make it more difficult for any dislocation to occur as it reduces mobility. This has a hardening effect on the metal. Phase diagram Using the phase diagram one can understand why the properties of steels change with differing carbon content. Figure 3.5: Phase Diagram The gamma phase, relates to an Austenite range which has a Face Centred Cubic (FCC) structure. The alpha phase relates to a ferritic Body Centered Cubic crystal structure. Ferrite is found extensively in automotive steels, its BCC structure is much less dense than the FCC of austenite which makes it easily formable and therefore relatively cheap to manufacture. Fe3C refers to cementite and the mixture of alpha (ferrite) + cementite is called pearlite. On the phase diagram steels only apply up to about 1.4% carbon. The eutectoid point is at 723 degrees and is where there are three phases in equilibrium. The eutectoid composition is Fe-0.83%C. The reaction that happens at the eutectoid point is: austenite > ferrite + cementite gamma > alpha + Fe3C High carbon content means a greater precense of austenite, whereas low carbon content will give less austenite and a more ferritic microstructure. The affect of these differing microstructures is reflected in their mechanical properties. This is because Ferrite is soft and ductile and Cementite is hard and brittle. It can be seen by looking at figure 3.5 that as the carbon content is increased, strength increases. This relationship occurs up to the eutectoid point after which it starts to reduce. This where cementite grain-boundaries are created. The figure below shows how the varying content of carbon in steel affects its properties and suitability for different applications. Figure 3.6 Carbon Steel Applications Lever rule The lever rule can be used to calculate expected proportions of the phases present in each of the tested carbon steel specimens. These values can then be compared to the values obtained through testing. Figure 3.7 Lever Rule Calculations: a = Ferrite a + Fe3C = Pearlite 0.1wt%C Normalised Steel Tensile Specimen: % Ferrite = (0.8- 0.1)   Ã‚   = 0.897   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8-0.02) % Pearlite= (0.1- 0.02)    = 0.103   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8- 0.02) 0.4wt%C Normalised Steel Tensile Specimen: % Ferrite = (0.8- 0.4)   Ã‚   = 0.513   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8-0.02) % Pearlite= (0.4- 0.02)    = 0.487   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8- 0.02) 0.8wt%C Normalised Steel Tensile Specimen: % Ferrite = (0.8- 0.8)    = 0   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   (0.8-0.02) % Pearlite= (0.8- 0.02)   = 1   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   (0.8- 0.02) These results suggest that as the carbon content increases the pearlite to ferrite ratio also increases. So the ratio of Pearlite to ferrite increases as carbon content is increased the material is made harder, stronger and more brittle but less ductile. These results obtained using the lever rule support the results obtained from the tensile test, showing the steel with the highest carbon content to be the least ductile and most brittle. The results are also supported by the findings from the hardness test which shows the steel with the highest carbon content to be the hardest. 3.2.2 Titanium The addition of Titanium to IFHS steels is particularly useful in the manufacturing of strip steels where good drawability is a requirement. The addition of Ti or Nb results in a lower Yield Strength/Tensile Strength ratio giving an increased formability. This can be seen in figure 3.8. When Titanium reacts with Carbon and Nitrogen it forms TiC and TiN, these precipitates work to delay recrystallisation of austenite, thus refining the grains to a favourable smaller size [12]. Figure 3.8: The effect of Titanium and Niobium on Yield Srength/UTS ratio [12] Titanium precipitates exist within steels and these affect the mechanical properties. TiN precipitates help to promote recrystallisation and encourage the {111} texture. TiS precipitates are commonly found in the austenite region as well as Ti4C2S2, Ti4C2S2 is formed by reacting with Carbon and in the highest regions of the austenite range there is little to no Carbon. These conditions are created at very high temperatures similar to those during hot rolling processes. This leaves the steel highly formable and suitable for deep drawability application such as car body panels. It is very difficult however to form Ti4C2S2 as it is less stable than TiS, although it can be encouraged through specific heat treatment processes. [13] 3.2.3 Vanadium Titanium is commonly added with Niobium to steels to increase formability through precipitation. However these additions can result in a retardation of recrystallisation meaning a higher temperature or longer soaking time is required for recyrstallisation to occur. Vanadium offers a replacement to Niobium in the form of carbides and nitrides, VC and VN, which does not cause such a drastic retardation of recyrstallisation. This is attractive to manufacturers as lower temperatures and shorter processing time during annealing are more cost effective. The effectiveness of Vandium in essentially lowering the recrystallisation temperature is shown in Figure 3.9. Figure 3.9: The effect of Ti + Nb, Ti + V and V stabilised steels on the Temperature for Complete Recrystallisation in 30 Seconds [44]. Figure 3.9 shows that the V only stabilised steel recrystallises at a lower temperature than the TiV and TiNb steels. 3.2.4 Sulphur Sulphur is found in all steels including Interstitial Free High Strength Steels. It acts as an interstitial elements and other elements to form precipitates such as TiS, MnS and Ti4C2S2. These precipitates have different effects on the mechanical properties of the material. In particular the precipitation of carbosulphides is beneficial to the steel as this causes the steel to form in the austenite range and helps to reduce the TiC formation which could occur during heat treatment processing and cause the material to become less likely to form the {111} texture.[13] Promoting Ti4C2S2 therefore encourages the formation of the favourable {111} texture, increasing the formability of the material. In order for Ti4C2S2 to develop, Sulphur, Carbon and Titanium must all be present, and processed in such a way as to form a reaction, which can difficult. 3.2.5 Niobium Niobium if found extensively in IFHS Steels reacting with carbon to form carbides such as NbC. Solute Niobium can be used to segregate austenite and ferrite grain boundaries and increase the strength of the austenite region [14]. As Niobium content increases the r-value decreases as well as the ductility. Generally Nb content is minimised as much as possible as the positive effect it has on strength in the austenite region is relatively small and is outweighed by the negative effect it has on ductility. Boron can be used instead of Niobium as it has a much greater effect on strength than Niobium. This can be seen in figure 3.9 Figure 3.9: Average Flow Stress vs. Temperature for B, C, and Nb and Mo solutes in steel [15]. 3.2.6 Phosphorus Phosphorus, P, is a common alloy of IFHS steel, offering increases in strength through solid solution hardening. Adding Phosphorus can also have a direct effect on the grains within a structure by increasing the Hall-Petch slope (described below). Adding P however can have a negative effect on the brittleness of the material. This can be particularly problematic during the cold working process where brittle fracture is a distinct possibility. The Hall-Petch relationship says that as the grain size decreases the yield strength of a material increases. This is due to the dislocations piling up at grain boundaries, which act as barriers to dislocation movement at low temperatures. If the grain size is large, then a high number of dislocations will pile up at the edge of the slip plane. When the stress exceeds a critical value the dislocations cross the boundary. So the larger the grain size, the lower the applied stress required to reach this critical stress at the grain boundary, meaning the larger the grain size, the lower the yield stress due to easier dislocation movement. This is true down to a grain size of 100nm. Below this size the yield strength remains constant or starts to decrease. This is effect is called the reverse Hall-Petch effect. Phosphorus along with Silicon and Manganese are added via solid solution strengthening to strengthen steel allowing for a thinner sheet of metal to be used for car body panels, and thus reducing the weight. Phosphorus is the most effective out of the three elements in terms of cost and strengthening effect. This can be seen below in figure 3.11 where the effects of P and S additions are compared. Figure 3.11: Comparison of Stress vs. Temperature between Phosphorus and Silicon microalloyed Steels [16]. Phosphorus is also found in the form of FeTiP precipitates. These precipitates have a negative affect on strength and drawability. The effects of these precipitates are greater in batch annealed steels than in continuous steels. This is due to the long soaking times required in batch annealing which provides optimum conditions and sufficient time for these precipitates to form [17]. 3.2.7 Manganese Manganese is added through solid solution strengthening to IFHS steels in a low concentration in order to react with the Sulphur to produce MnS precipitates. These MnS precipitates act to refine grain structure during processing when there is a transformation in phase between austenite and ferrite. Mn is to strengthen steels through solid solution strengthening. The effect of Mn is relatively small in the austenite range but compared to the ferrite range. This is due to a difference in Mn solubility between the austenite and ferrite ranges. Where Mn in ferrite is 10wt% higher than in austenite [18] Mn acts to stabilize the austenite region and slows down the rate of austenite transformation and also the temperature at which the transformation takes place. This lowering of transformation temperature between austenite and ferrite promotes finer grains through grain refinement. Mn can be found in oxide and sulphide forms as well as combinations of the two, oxysulphides. These oxides and sulphides act to deoxidise and desulphurise the steel. When in sulphide form, MnS helps to reduce embrittlement of steel without reducing hardness. When mixed with common impurities such as Al2O3, SiO2, MnO, CaO, CaS and FeS an increase in hardness and strength occurs [19]. When in the oxide form, MnO at the surface acts a barrier layer to prevent surface oxidisation and corrosion. 3.2.8 Silicon Silicon is a useful element and is used to increase the strength through solid solution strengthening, although there is a compromise as increasing Silicon content decreases ductility. Silicon is also found in oxide form, as silicon dioxide. Silicon dioxide is found with Manganese Oxide or as Silicomanganese to give a strong oxygen stabilisation and prevent corrosion of steel. [20]. 3.2.9 Aluminium Aluminium is used to deoxidise steel by reacting with oxygen within the steel to form Al2O3. These Aluminium Oxides are later removed leaving an oxygen free steel. However the low density of Aluminium means that oxidisation could occur at the steel interface resulting in corrosion. Aluminium content can have a negative effect on formability. This is due to the precipitation of AlN during recrystallisation preventing the {111} development and thus preventing the formation of finer grains. So minimising the amount of AlN in solid solution results in higher formability. A more stable alternative to AlN which is commonly used in IFHS steels is TiN. 3.3 Hardening and processing There are many different compositions of steel which offer various advantageous properties. The main reason for altering composition or alloying is to strengthen the material. This can be done in several ways; 3.3.1 Precipitation strengthening This process uses heat treatment to raise the yield strength of a material. As temperature changes during heat treatment processing, fine particles are produced due to differing melting points of impurities. These fine particles impede dislocation movement. This in turn reduces the ductility and plasticity of the material and increases its hardness. 3.2.2 Solid – solution strengthening Solid solution strengthening is a form of alloying. It is a commonly used technique to improve the strength of a material. Atoms of the alloying element are added to the crystal lattice of the base metal via diffusion. There are two ways in which this can occur, depending on the size of the alloying alloying element. These are via substitutional solid solution, and interstitial solid solution. Substitutional solid solution This takes place when the sizes of the alloying atoms are equal in size to the base atoms, (Differing in size by no more than 15% according to the Hume-Rothery rules) The alloying atoms replace the solvent atoms and assume their lattice positions. The solute atoms can produce a slight distortion of the crystal lattice, due to the size variation. The amount of distortion increases with the size of the solute atom. This distortion has an effect on microstructural properties. The formation of slip planes is altered making dislocation movement more difficult, meaning a higher stress is required to move the dislocations. This gives the material a higher strength. A generalisation associated with substitution is that large substitutional atoms put the structure under compressive stress, and small substitutional atoms give tensile stress. Interstitial solid solution This occurs when the alloying atoms are much smaller than the base atoms. The alloying atoms fit into spaces within the crystal lattice. This is the case with carbon in steel, where carbon is a solute in the iron solvent lattice. The carbon atoms are less than half the size of the iron atoms so an interstitial solid solution forms. 3.3.3 Processing The final properties of steel are greatly affected by the manner in which it is first made and then processed. Typical processes include steel making, casting, hot and cold rolling and annealing. Each individual process has a distinct affect on the properties of the steel. To make the steel free from interstitial elements, Ti and Nb are often added to react with interstitials after a process called vacuum degassing. Vacuum degassing is the name given to the process where a metal is melted within a vacuum and the gasses are evaporated out. Hot and cold rolling Hot rolling is the first process to take place after steel making. After steel has been cast into uniform slabs or billets it is the rolled under a high temperature to reduce its cross sectional thickness. The hot rolling process is undertaken at a temperature above that at which recrystallisation occurs. Hot rolling reduces allows recrysallisation to occur during processing (dynamic recrystallisation) and the material is left stress free due the new grain nucleation and equiaxed grains. Effect of hot working on microstructure: Hot working occurs at high temperatures, this means that there is often enough thermal energy present for recrsytallisation to occur during deformation. This is called dynamic recrystallisation and it occurs with most metals, apart from aluminium. Recrystallisation occurs during the working process and also as the metal is cooling. Dynamic recrystallisation occurs by new grains nucleating at existing grain boundaries. The amount of recyrstallisation depends on several factors. It depends on the strain rate, temperature and amount of strain on the metal. Generally, as strain within the metal increases, so does the amount of recrystallisation. Cold working is when steel is plastically deformed below its recrystallisation temperature. This process increases the yield strength due to the plastic deformation causing slight defects within the microstructure of the metal. These defects make it difficult for slip planes to move. The grain size of the metal is also reduced, making the material harder through a process called Hall petch hardening. Hall Petch hardening, also known as grain boundary strengthening, increases materials strength by altering the grain size. This is because grain boundaries act as barriers to dislocation movement. So altering the grain size, through hot and cold rolling at various temperatures and rates will have an effect on dislocation movement and yield strength. Cold working will increase the strength of the metal by making it increasingly difficult for slip to occur. However as more and more of the larger grains split to form smaller grains the ductility is greatly reduced as the material hardens. Eventually fracture would occur. To avoid this, the material is annealed. Cold working occurs at a temperature below 0.4 of the metals melting point. Some of the energy created by the process is expelled as heat but some energy is stored within the structure putting it into a high energy state. The energy is stored within the grain boundaries of the deformed crystals and within the stress fields of the dislocations created through the plastic deformation. The structure is highly stressed after cold working and would prefer to return to its former low energy state. It is howeve Microstructure-mechanical Property Relationships Microstructure-mechanical Property Relationships Microstructure-mechanical property relationships in high strength low alloy steels for automotive applications Chapter 1 Introduction The production of steel is an ancient process which has evolved over time. Where and when Steel was first created is unknown and a topic of much debate, however most historians believe earliest production of steel originates from China from as early as 202BC. A later form of steel named Wootz Steel was later developed in India, which used wind power to fuel a furnace producing nearly pure steel. In the 11th century China developed steel further was the first country to mass produce steel. Two methods were developed. A berganesque method which produced inhomogeneous steel, and a process which that relied on partial decarbonisation through repeated forging under a cold blast, this was seen as the superior method, and one which lead on to the Bessemer process [1].The Bessemer process involved using a blast furnace to extract iron from its ore and is the basis of modern steel extraction. Steel is produced firstly by extracting iron from its ore. Iron extraction differs slightly from other metals as it can only be found naturally in oxide form. This means that a smelting process is required. This involves a reduction reaction followed by alloying with additional elements like carbon to stabilise and strengthen the steel. Iron smelting requires a high temperature which produces a ferrous material made of a combination of iron and steel. The addition of alloying elements such as carbon affect the materials properties greatly. Changing the temperature at which the iron is smelted affects the phase of the resultant steel, giving rise to the possibility of producing steels with varying properties which are suitable for a range of applications. In the automotive industry, body frames were originally made of hardwood. This was replaced in 1923 when the American Rolling Company developed steel sheet production. The wooden frames were inferior in energy absorption which was a big safety issue. Steel was also much easier to form than wood and did not warp over time. As the automobile has evolved over time, there has been an increasing public awareness of the environmental impact of the car. This has forced manufacturers to produce lighter cars which are more economical. This brought about the development of thin, highly formable sheet steel. The main competitor to steel in the automotive industry is Aluminium, which offers a much better strength to weight ratio and also a better resistance to corrosion. However steel is still the most commonly used material mainly due to lower production cost. Increasing competition from aluminium is forcing the development of modern steels. Steel naturally has a higher formability and elongation than aluminium which is one of the reasons it is used so extensively in the automotive sector. This can be seen in Figure 1.1: Figure 1.1- Yield strength vs total elongation of aluminium alloys and automotive steels [3] Ultra low carbon (ULC) steels are used commonly in the production of automobiles. Their, highy formability and suitability for hot dip galvanising make them very attractive to automobile producers[4]. Pressure is being put on the manufacturers to produce lightweight cars that minimise emissions without compromising safety. Metallic properties required to achieve this consist of a high tensile strength, high r- value, good ductility and also the ability to be made resistant to corrosion (either naturally or through the use of chemical surface treatment). Various high performance steels have been developed to meet these requirements, of these, one of the most important being HSLA steels. High strength low alloy steels provide a much better strength to weight ratio than conventional low carbon steels allowing for thinner grades to be used, saving weight. HSLA steels have a manganese content of up to 1.5%, as well as microalloying elements such as vanadium and titanium. HSLA steels are increasingly replacing traditional low carbon steels for many automotive parts. This is due to their ability to reduce weight without compromising strength and dent resistance. Typical applications include door-intrusion beams, chassis members, reinforcing and mounting brackets, steering and suspension parts, bumpers, and wheels [5]. High strength low alloy steel properties are determined by the way in which they are processed. High deep drawability, can be achieved through precipitation of elements by annealing to produce a strong {111} recrystallisation texture [7], producing highly formable steels which are very desirable for automotive applications. In this study, two grades of IFHS strips are studied. A titanium only stabilised steel grade and a titanium-vanadium stabilised steel grade. These have been treated using a Viking tube furnace and studied using a scanning electron microscope, Photoshop and Optilab Software. Both steel grades have been studied using carefully selected thermo mechanical heat treatment cycles. The heating variables are expected to cause varying effects to the mechanical properties and microstructure of the two materials. The addition of vanadium in one of the steel grades is also expected to influence the mechanical properties. With the data obtained from my experiments I hope to determine the optimum processing route for similar HSLA steels. Chapter 2 Aims Carry out selective batch annealing heat treatments on two microalloyed High Strength IF strip steels. Measure grain size evolution samples using scanning electron microscopy and quantitave optical microscopy techniques. Measure mechanical properties of obtained samples using hardness and tensile testing techniques Determine the optimum processing characteristics, resulting in optimum mechanical property characteristics. Chapter 3 Literature Review 3.1 AUTOMOTIVE STEELS Automotive manufacturers make use of many different metals in the production of cars, of which the most predominant being steel. This is for several reasons, steel is relatively easy to recycle in comparison with polymers and aluminium, and this is an issue which is growing in importance as the public are becoming more and more environmentally aware. Steel is also a very good material in terms of its practicality, as it is easily welded, has good formability, elongation and ductility. As the environmental impact of cars is becoming more and more important, stringent regulations regarding emissions are being forced upon manufacturers. One of the ways that manufacturers have chosen to meet these requirements is to make the cars lighter by switching from mild steel to high strength steel grades which enables components to have a thinner cross section, saving weight. The three main types of steels used in automobiles today are; Low strength (IF and mild steels), High strength (Carbon manganese, bake hardening, IFHS and HSLA) Advanced high strength steels (dual-phase, complex phase, transformation induced plasticity and matensitic steels) These steel types can be seen below on figure 3.1 comparing their elongation and strength. Figure 3.1: Classification of automotive steels [8]. 3.1.1 Mild Steels Mild steels are normally found in two different forms for automotive purposes. Drawn Quality and Aluminium killed. These are both cheap to manufacture are used for high volume parts. They are usually of a ferrite microstructure. [8] 3.1.2 Interstitial Free Steels IF steels are used for car body panels extensively due largely to their deep drawability. The high elongation achieved in comparison with other steel grades can be seen in figure 3.1.The main characteristic of IF steel is a low carbon and nitrogen content. These elements are removed from solution by adding specific elements for alloys. Commonly used elements for this microalloying process include Manganese, Sulphur, Titanium and Niobium. As well as a deep drawability, IF steel have low yield strength but a poor dent resistance which is undesirable for certain automotive applications [6] Bake Hardening Steels BH steels keep carbon in solution either during processing before it is precipitated or during the paint baking state [8]. This strengthens the steel through solid solution strengthening, resulting in steel with both high formability and high strength. 3.1.4 Carbon-Manganese Steels Carbon-manganese steels are solid solution strengthened and are used in strip form on automobile bodies, although they are becoming replaced by lighter steel grades. They offer high drawability and are relatively cheap to produce. [9] D.T.Llewellyn: Steel: Metallurgy and Applications, Butterworth-Heinemann Ltd, Great Britain, 1992. 3.1.5 High-Strength Low-Alloy (HSLA) Steels HSLA steels are strengthened through the addition of microallying elements. These react with the carbon and nitrogen within the steel to form carbides and nitrides. Common elements include Nb, V and Ti. The resultant steel has both high strength and a high formability due to very fine grain sizes [10] Dual-Phase (DP) Steels Dual-phase steels contain two phases within their microstructure. These are ferrite and martensite. This two phase structure is produced through a complex series of contolled heating and cooling. Martensite regions are produced by heating and rapidly cooling. It is the marteniste regions tha give the hardness to the material where as the ferrite regions are much softer. The structure of DP steels takes advantages of the properties of each of the phases, where the hard maternsite regions are surrounded by softer ferrite which reduces brittleness, shown in figure 3.2. DP steel has good ductility, low yield strength but high work hardening rate [8]. Figure 3.2: Microstructure of DP steel [8]. 3.1.7 Transformation-Induced Plasticity (TRIP) Steels TRIP steels consist of a mainly ferrite microstructure with a low austenite content within the matrix. An isothermal hold during production at an intermediate temperature is used to produce bainite [8]. Strength is increased by transformationing of austenite regions to harder martensite regions. TRIP steels have a good work hardening rate and good strength. Work hardening in TRIP steels continues at higher strain levels than those of DP steels so TRIP steels is a superior material from this aspect. Figure 3.3 shows the multi phase microstructure of TRIP steel. Figure 3.3: Microstructure of TRIP steel [8]. Martensitic (MS) Steel MS steels are mainly of a martensitic microstructure but contain small amounts of ferrite and bainite. During heat treatment the steel is rapidly cooled transforming austenite into martensite. This gives a very high tensile strength since martensite produces a very hard material, but the drawback is this also gives a low formability. In order to overcome this low formability further processing such as heat treatments must be undertaken. [11] 3.1.9 High Strength Interstitial Free (HS-IF) Steels HSIF steels are strengthened through the addition of microalloying elements. Commonly used alloying elements include P, B, Si, Mn, Ti, N. The combinations in which the microalloying elements are used have an effect on the properties of resultant steel allowing a range of requirements to be met. HSIF steels can produce nearly twice the potential yield strength as conventional IF steels, although there is a reduction in formability. 3.2 Microalloying Elements 3.2.1 Carbon Carbon is one of the most important interstitial elements within steel, giving very different mechanical properties as its percentage content is altered and therefore must be studied in depth. Carbon is an element commonly found in automotive steels due to its high strength properties. Although adding carbon increases strength, it also affects the formability, i.e. its deep drawability. A set of experiments were carried out to determine the effect of carbon content within steel. When analysing the tensile test results it was noted that the ultimate tensile strength, the proof stress and the yield stress all increased as the amount of carbon increased in the steel. The plastic region as well as the general elongation of the steel under tensile stress decreased as the carbon content increased. These are significant changes in the mechanical properties. Hardness and Tensile strength increase as carbon content approaches 0.85% C as shown in figure 3.4. The elongation percentage decreases as the carbon content increases. This suggests that the more carbon present in the material, the stronger and less ductile it becomes. Figure 3.4: Affect of Carbon content in Steel Yield Strength Carbon content influences the yield strength of steel because carbon molecules fit into the interstitial crystal lattice sites of the body-centred cubic arrangement of the iron molecules. The interstitial carbons make it more difficult for any dislocation to occur as it reduces mobility. This has a hardening effect on the metal. Phase diagram Using the phase diagram one can understand why the properties of steels change with differing carbon content. Figure 3.5: Phase Diagram The gamma phase, relates to an Austenite range which has a Face Centred Cubic (FCC) structure. The alpha phase relates to a ferritic Body Centered Cubic crystal structure. Ferrite is found extensively in automotive steels, its BCC structure is much less dense than the FCC of austenite which makes it easily formable and therefore relatively cheap to manufacture. Fe3C refers to cementite and the mixture of alpha (ferrite) + cementite is called pearlite. On the phase diagram steels only apply up to about 1.4% carbon. The eutectoid point is at 723 degrees and is where there are three phases in equilibrium. The eutectoid composition is Fe-0.83%C. The reaction that happens at the eutectoid point is: austenite > ferrite + cementite gamma > alpha + Fe3C High carbon content means a greater precense of austenite, whereas low carbon content will give less austenite and a more ferritic microstructure. The affect of these differing microstructures is reflected in their mechanical properties. This is because Ferrite is soft and ductile and Cementite is hard and brittle. It can be seen by looking at figure 3.5 that as the carbon content is increased, strength increases. This relationship occurs up to the eutectoid point after which it starts to reduce. This where cementite grain-boundaries are created. The figure below shows how the varying content of carbon in steel affects its properties and suitability for different applications. Figure 3.6 Carbon Steel Applications Lever rule The lever rule can be used to calculate expected proportions of the phases present in each of the tested carbon steel specimens. These values can then be compared to the values obtained through testing. Figure 3.7 Lever Rule Calculations: a = Ferrite a + Fe3C = Pearlite 0.1wt%C Normalised Steel Tensile Specimen: % Ferrite = (0.8- 0.1)   Ã‚   = 0.897   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8-0.02) % Pearlite= (0.1- 0.02)    = 0.103   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8- 0.02) 0.4wt%C Normalised Steel Tensile Specimen: % Ferrite = (0.8- 0.4)   Ã‚   = 0.513   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8-0.02) % Pearlite= (0.4- 0.02)    = 0.487   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  (0.8- 0.02) 0.8wt%C Normalised Steel Tensile Specimen: % Ferrite = (0.8- 0.8)    = 0   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   (0.8-0.02) % Pearlite= (0.8- 0.02)   = 1   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   (0.8- 0.02) These results suggest that as the carbon content increases the pearlite to ferrite ratio also increases. So the ratio of Pearlite to ferrite increases as carbon content is increased the material is made harder, stronger and more brittle but less ductile. These results obtained using the lever rule support the results obtained from the tensile test, showing the steel with the highest carbon content to be the least ductile and most brittle. The results are also supported by the findings from the hardness test which shows the steel with the highest carbon content to be the hardest. 3.2.2 Titanium The addition of Titanium to IFHS steels is particularly useful in the manufacturing of strip steels where good drawability is a requirement. The addition of Ti or Nb results in a lower Yield Strength/Tensile Strength ratio giving an increased formability. This can be seen in figure 3.8. When Titanium reacts with Carbon and Nitrogen it forms TiC and TiN, these precipitates work to delay recrystallisation of austenite, thus refining the grains to a favourable smaller size [12]. Figure 3.8: The effect of Titanium and Niobium on Yield Srength/UTS ratio [12] Titanium precipitates exist within steels and these affect the mechanical properties. TiN precipitates help to promote recrystallisation and encourage the {111} texture. TiS precipitates are commonly found in the austenite region as well as Ti4C2S2, Ti4C2S2 is formed by reacting with Carbon and in the highest regions of the austenite range there is little to no Carbon. These conditions are created at very high temperatures similar to those during hot rolling processes. This leaves the steel highly formable and suitable for deep drawability application such as car body panels. It is very difficult however to form Ti4C2S2 as it is less stable than TiS, although it can be encouraged through specific heat treatment processes. [13] 3.2.3 Vanadium Titanium is commonly added with Niobium to steels to increase formability through precipitation. However these additions can result in a retardation of recrystallisation meaning a higher temperature or longer soaking time is required for recyrstallisation to occur. Vanadium offers a replacement to Niobium in the form of carbides and nitrides, VC and VN, which does not cause such a drastic retardation of recyrstallisation. This is attractive to manufacturers as lower temperatures and shorter processing time during annealing are more cost effective. The effectiveness of Vandium in essentially lowering the recrystallisation temperature is shown in Figure 3.9. Figure 3.9: The effect of Ti + Nb, Ti + V and V stabilised steels on the Temperature for Complete Recrystallisation in 30 Seconds [44]. Figure 3.9 shows that the V only stabilised steel recrystallises at a lower temperature than the TiV and TiNb steels. 3.2.4 Sulphur Sulphur is found in all steels including Interstitial Free High Strength Steels. It acts as an interstitial elements and other elements to form precipitates such as TiS, MnS and Ti4C2S2. These precipitates have different effects on the mechanical properties of the material. In particular the precipitation of carbosulphides is beneficial to the steel as this causes the steel to form in the austenite range and helps to reduce the TiC formation which could occur during heat treatment processing and cause the material to become less likely to form the {111} texture.[13] Promoting Ti4C2S2 therefore encourages the formation of the favourable {111} texture, increasing the formability of the material. In order for Ti4C2S2 to develop, Sulphur, Carbon and Titanium must all be present, and processed in such a way as to form a reaction, which can difficult. 3.2.5 Niobium Niobium if found extensively in IFHS Steels reacting with carbon to form carbides such as NbC. Solute Niobium can be used to segregate austenite and ferrite grain boundaries and increase the strength of the austenite region [14]. As Niobium content increases the r-value decreases as well as the ductility. Generally Nb content is minimised as much as possible as the positive effect it has on strength in the austenite region is relatively small and is outweighed by the negative effect it has on ductility. Boron can be used instead of Niobium as it has a much greater effect on strength than Niobium. This can be seen in figure 3.9 Figure 3.9: Average Flow Stress vs. Temperature for B, C, and Nb and Mo solutes in steel [15]. 3.2.6 Phosphorus Phosphorus, P, is a common alloy of IFHS steel, offering increases in strength through solid solution hardening. Adding Phosphorus can also have a direct effect on the grains within a structure by increasing the Hall-Petch slope (described below). Adding P however can have a negative effect on the brittleness of the material. This can be particularly problematic during the cold working process where brittle fracture is a distinct possibility. The Hall-Petch relationship says that as the grain size decreases the yield strength of a material increases. This is due to the dislocations piling up at grain boundaries, which act as barriers to dislocation movement at low temperatures. If the grain size is large, then a high number of dislocations will pile up at the edge of the slip plane. When the stress exceeds a critical value the dislocations cross the boundary. So the larger the grain size, the lower the applied stress required to reach this critical stress at the grain boundary, meaning the larger the grain size, the lower the yield stress due to easier dislocation movement. This is true down to a grain size of 100nm. Below this size the yield strength remains constant or starts to decrease. This is effect is called the reverse Hall-Petch effect. Phosphorus along with Silicon and Manganese are added via solid solution strengthening to strengthen steel allowing for a thinner sheet of metal to be used for car body panels, and thus reducing the weight. Phosphorus is the most effective out of the three elements in terms of cost and strengthening effect. This can be seen below in figure 3.11 where the effects of P and S additions are compared. Figure 3.11: Comparison of Stress vs. Temperature between Phosphorus and Silicon microalloyed Steels [16]. Phosphorus is also found in the form of FeTiP precipitates. These precipitates have a negative affect on strength and drawability. The effects of these precipitates are greater in batch annealed steels than in continuous steels. This is due to the long soaking times required in batch annealing which provides optimum conditions and sufficient time for these precipitates to form [17]. 3.2.7 Manganese Manganese is added through solid solution strengthening to IFHS steels in a low concentration in order to react with the Sulphur to produce MnS precipitates. These MnS precipitates act to refine grain structure during processing when there is a transformation in phase between austenite and ferrite. Mn is to strengthen steels through solid solution strengthening. The effect of Mn is relatively small in the austenite range but compared to the ferrite range. This is due to a difference in Mn solubility between the austenite and ferrite ranges. Where Mn in ferrite is 10wt% higher than in austenite [18] Mn acts to stabilize the austenite region and slows down the rate of austenite transformation and also the temperature at which the transformation takes place. This lowering of transformation temperature between austenite and ferrite promotes finer grains through grain refinement. Mn can be found in oxide and sulphide forms as well as combinations of the two, oxysulphides. These oxides and sulphides act to deoxidise and desulphurise the steel. When in sulphide form, MnS helps to reduce embrittlement of steel without reducing hardness. When mixed with common impurities such as Al2O3, SiO2, MnO, CaO, CaS and FeS an increase in hardness and strength occurs [19]. When in the oxide form, MnO at the surface acts a barrier layer to prevent surface oxidisation and corrosion. 3.2.8 Silicon Silicon is a useful element and is used to increase the strength through solid solution strengthening, although there is a compromise as increasing Silicon content decreases ductility. Silicon is also found in oxide form, as silicon dioxide. Silicon dioxide is found with Manganese Oxide or as Silicomanganese to give a strong oxygen stabilisation and prevent corrosion of steel. [20]. 3.2.9 Aluminium Aluminium is used to deoxidise steel by reacting with oxygen within the steel to form Al2O3. These Aluminium Oxides are later removed leaving an oxygen free steel. However the low density of Aluminium means that oxidisation could occur at the steel interface resulting in corrosion. Aluminium content can have a negative effect on formability. This is due to the precipitation of AlN during recrystallisation preventing the {111} development and thus preventing the formation of finer grains. So minimising the amount of AlN in solid solution results in higher formability. A more stable alternative to AlN which is commonly used in IFHS steels is TiN. 3.3 Hardening and processing There are many different compositions of steel which offer various advantageous properties. The main reason for altering composition or alloying is to strengthen the material. This can be done in several ways; 3.3.1 Precipitation strengthening This process uses heat treatment to raise the yield strength of a material. As temperature changes during heat treatment processing, fine particles are produced due to differing melting points of impurities. These fine particles impede dislocation movement. This in turn reduces the ductility and plasticity of the material and increases its hardness. 3.2.2 Solid – solution strengthening Solid solution strengthening is a form of alloying. It is a commonly used technique to improve the strength of a material. Atoms of the alloying element are added to the crystal lattice of the base metal via diffusion. There are two ways in which this can occur, depending on the size of the alloying alloying element. These are via substitutional solid solution, and interstitial solid solution. Substitutional solid solution This takes place when the sizes of the alloying atoms are equal in size to the base atoms, (Differing in size by no more than 15% according to the Hume-Rothery rules) The alloying atoms replace the solvent atoms and assume their lattice positions. The solute atoms can produce a slight distortion of the crystal lattice, due to the size variation. The amount of distortion increases with the size of the solute atom. This distortion has an effect on microstructural properties. The formation of slip planes is altered making dislocation movement more difficult, meaning a higher stress is required to move the dislocations. This gives the material a higher strength. A generalisation associated with substitution is that large substitutional atoms put the structure under compressive stress, and small substitutional atoms give tensile stress. Interstitial solid solution This occurs when the alloying atoms are much smaller than the base atoms. The alloying atoms fit into spaces within the crystal lattice. This is the case with carbon in steel, where carbon is a solute in the iron solvent lattice. The carbon atoms are less than half the size of the iron atoms so an interstitial solid solution forms. 3.3.3 Processing The final properties of steel are greatly affected by the manner in which it is first made and then processed. Typical processes include steel making, casting, hot and cold rolling and annealing. Each individual process has a distinct affect on the properties of the steel. To make the steel free from interstitial elements, Ti and Nb are often added to react with interstitials after a process called vacuum degassing. Vacuum degassing is the name given to the process where a metal is melted within a vacuum and the gasses are evaporated out. Hot and cold rolling Hot rolling is the first process to take place after steel making. After steel has been cast into uniform slabs or billets it is the rolled under a high temperature to reduce its cross sectional thickness. The hot rolling process is undertaken at a temperature above that at which recrystallisation occurs. Hot rolling reduces allows recrysallisation to occur during processing (dynamic recrystallisation) and the material is left stress free due the new grain nucleation and equiaxed grains. Effect of hot working on microstructure: Hot working occurs at high temperatures, this means that there is often enough thermal energy present for recrsytallisation to occur during deformation. This is called dynamic recrystallisation and it occurs with most metals, apart from aluminium. Recrystallisation occurs during the working process and also as the metal is cooling. Dynamic recrystallisation occurs by new grains nucleating at existing grain boundaries. The amount of recyrstallisation depends on several factors. It depends on the strain rate, temperature and amount of strain on the metal. Generally, as strain within the metal increases, so does the amount of recrystallisation. Cold working is when steel is plastically deformed below its recrystallisation temperature. This process increases the yield strength due to the plastic deformation causing slight defects within the microstructure of the metal. These defects make it difficult for slip planes to move. The grain size of the metal is also reduced, making the material harder through a process called Hall petch hardening. Hall Petch hardening, also known as grain boundary strengthening, increases materials strength by altering the grain size. This is because grain boundaries act as barriers to dislocation movement. So altering the grain size, through hot and cold rolling at various temperatures and rates will have an effect on dislocation movement and yield strength. Cold working will increase the strength of the metal by making it increasingly difficult for slip to occur. However as more and more of the larger grains split to form smaller grains the ductility is greatly reduced as the material hardens. Eventually fracture would occur. To avoid this, the material is annealed. Cold working occurs at a temperature below 0.4 of the metals melting point. Some of the energy created by the process is expelled as heat but some energy is stored within the structure putting it into a high energy state. The energy is stored within the grain boundaries of the deformed crystals and within the stress fields of the dislocations created through the plastic deformation. The structure is highly stressed after cold working and would prefer to return to its former low energy state. It is howeve