Essay on William Shakespeares Othello - 574 Words

William Shakespeares Othello The play Othello was said to have been written in 1603/4, but no one really knows. It was first performed in front of king James I. It was very original because it had a black tragic hero and at that time it was very rare too see a black character let alone a main one. The key themes are the same in most of Shakespeares plays (love, jealousy, appearance and reality, dark and light. The main theme is Othellos jealousy, which results in his downfall. Vital to the play is the devilish Iago, one of Shakespeares most fascinating villains. His motives for manipulating Othello remain in mystery. However, Othellos race is vital to the success of Iagos schemes. In the rest†¦show more content†¦Were it my cue to fight, I should have known it without a prompter(Act I, ii, lines 22-24). This is showing what control he has over them. The nature of Othellos character is of a dark man. A dark man, not only because he is black, but also because his whole person is very mysterious. He is mysterious in that he believes there is magic brewing everywhere, when Desdemona loses her napkin he says to here To lose it or givet away à ¢Ã¢â€š ¬Ã‚ ¦Ãƒ ¢Ã¢â€š ¬Ã‚ ¦ match . With this dark side he is also very outgoing, and not very bright. He isnt observant and the schemes of Iago work well on him. For all the dangers and encounters he has been involved in, this man is still naive of the corruptness of other individuals. Othello has a trusting nature in which he gives it all. He put all his trust in Iago during times of war and during Othellos marriage to Desdemona. This wasnt very bright of Othello; even if he werent so trusting or more corrupt he still wouldnt realize Iago was lying. He considered Iago as honest. For example, Othello had told the Duke, So please your grace, my ancient; a man he is of honesty and trust. To his conveyance I assign my wife, with what else needful your good grace shall think, to be sent after me (act I,iii,). As well as this he calls him honest and good numerous of times. The change over Othellos is very strong. Through the whole first act you can pictureShow MoreRelatedWilliam Shakespeares Othello997 Words   |  4 Pagesa person chooses to act around a certain group of people can be out of courteousness or his or her bad nature. William Shakespeare does not only shed light towards this topic but allows his audience to distinguish appearance versus reality. Shakespeares Othello and sonnets 93 and 138 demonstrate being who you are in reality triumphs over appearance and what you seem to be. In Othello, Shakespeare illustrates the importance reality takes place in identifying a persons true character as early asRead More William Shakespeares Othello1440 Words   |  6 PagesWilliam Shakespeares Othello A significant moment in Othello demonstrates the theme of binaries questioned in many of Shakespeares works. Addressing the Duke and senators, Othello says: Let her have your voice. Vouch with me heaven, I therefore beg it not To please the palate of my appetite, Nor to comply with heat--the young affects In me defunct--and proper satisfaction, But to be free and bounteous to her mind; And heaven defend your good souls that you think I will your seriousRead MoreWilliam Shakespeares Othello1173 Words   |  5 Pages Othello is set in a world and focuses on the passions and personalities of its major figures. (Thomas). Othello is a tragedy by William Shakespeare. The work revolves around four central characters: Othello, Othellos wife Desdemona, his lieutenant Cassio and advisor Iago. The play appeared in seven editors between 1622 and 1705. The themes of the story are racism, love, jealousy, and betrayal. Othello is a black soldier who is accused of stealing his wife Desdemona. Although Desdemonas fatherRead More William Shakespeares Othello Essay2198 Words   |  9 PagesWilliam Shakespeares Othello Every artist needs a subject to draw inspiration from—an idea to develop into a masterpiece. Leonardo da Vinci had Madame Lisa to portray in paint. The Beach Boys had Rhonda to render in rhyme. And William Shakespeare had one of one hundred stories written by Giraldi Cinthio to help him create his masterpiece, Othello. Each artist creates his own interpretation from his source. Shakespeare transformed the core of Cinthio’s story into a tragedy. A tragedy isRead More Othello as the Greater Evil in William Shakespeare’s Othello1842 Words   |  8 PagesOthello as the Greater Evil in William Shakespeare’s Othello What makes one person to be considered evil, while another is considered righteous? The character Iago, in William Shakespeare’s Othello, could be considered evil because of his plot against Cassio and Othello. Othello, could be considered righteous, because he believes his wife has been unfaithful. The line between these two labels, evil or righteous, is thin. Ultimately, actions speak louder than words. Iago is evil in his actionsRead MoreWilliam Shakespeares Othello629 Words   |  3 Pagescharacteristics of human beings is the necessity to survive. In Shakespeare’s play, Othello survival is taken to the extreme by the character, Iago. Iago’s selfishness is what ultimately drives him to manipulate the people around him. Initially Iago manipulates a character by the name of Roderigo. Roderigo is a Venetian gentleman that is in love with the wife of Othello, Desdemona and will do whatever it takes to win her over from Othello. Roderigo who is oblivious to the idea and fact that Iago isRead MoreWilliam Shakespeares Othello827 Words   |  3 Pagestragedies. One of the tragedies was the play Othello. The two characters that stuck out the most were Othello, the moor, and his beautiful wife Desdemona. The couple had certain mishaps but most readers did not expect a melodramatic plot twist. Othello had many downfalls, including insecurity. In the play Othello, the lack of communication between Desdemona and Othello was the cause for their deaths. Iago had major hatred toward Othello because Othello did not employ him as his lieutenant. Iago knewRead MoreWilliam Shakespeares Othello2192 Words   |  9 PagesOthello is commonly referred to as just Othello but the full name of the play is The Tragedy of Othello, the Moor of Venice. The tragedy of Othello is concise with Shakespeare’s other more popular works. Upon dissecting the play the most recognizable themes are the play’s complex and prevalent ambivalences of love and hate, jealousy, and perniciousness. Title and playwright â€Å"The Tragedy of Othello, the Moor of Venice is believed to have been based primarily on the Italian short story Un CapitanoRead More Racism in William Shakespeares Othello Essay1059 Words   |  5 PagesRacism in William Shakespeares Othello The play, Othello, is certainly, in part, the tragedy of racism. Examples of racism are common throughout the dialog. This racism is directed toward Othello, a brave soldier from Africa and currently supreme commander of the Venetian army. Nearly every character uses a racial slur to insult Othello at one point in the play. Even Emilia sinks to the level of insulting Othello based on the color of his skin. The character that most commonly makes racistRead More Iago in William Shakespeares Othello Essay1229 Words   |  5 PagesIago in William Shakespeares Othello William Shakespeare, born: 1564 died: 1616, is considered one of the greatest writers who has ever lived. He had a unique way of putting things into words. All of his plays, sonnets, and poems have gotten great recognition. But when Shakespeare wrote Othello he created one of the most controversial villains of all times; Iago. He is best described as disturbing, ruthless, and amoral. No other character can even come close to his evil (Iago: The 1). Iago

The Supply Of Transportation Gets Its Supply From...

Alberta Merriweather August 22 2014 KGA Microeconomics of Transportation The supply of transportation gets its supply from individual firms known as chain managements who seek to coordinate the flow of materials, product, and information between supplies. The goal of the business is to find ways to save money in reducing the amount, the size in material, and no longer useful supply. Supply chain synchronization is one of the big firms within many firms in the challenge of supply chain management and Its duties is to integrate operations across multiple firms to facilitate logistical operations across multiple firms and so that participants would benefit from jointly planning and implementing logistical operations. Individual firms†¦show more content†¦The supply chain Logistical system has performance cycles that is the fundamental unit for integrated logistics across the supply chain. Second, the performance cycle structure of a supply chain that is concerned with customer relationship management, manufacturing, or procurement. However, conside rable differences exist in control that an individual firm can exercise based on the specific type of performance cycle. Third, regardless of how vast and complex the overall supply chain structure, essential interfaces and control processes must be identified and evaluated in terms of individual performance cycle arrangements and associated managerial accountability. The objective of logistics in all operating areas is to reduce performance cycle uncertainty and the dilemma is that the structure of the performance cycle itself, operating conditions, and the quality of logistical operations all randomly introduce operational variance. The performance cycle illustration is based on finished goods inventory delivery and time distributions as it reflect operational history for each task of the performance cycle. Government are involved in providing transportation because it is necessary for economic development, for carrying out certain other functions of the government like as for pu blic safety or making it easier for individuals to reach places and for national defense. In the United States, airlines are run as private firm, while airports and air traffic control

Alternative to Commercial Software Volume †MyAssignmenthelp.com

Question: Discuss about the Alternative to Commercial Software Volume. Answer: Introduction: The Company that I will dicuss is referred to as NESTLE which has grown to a successful business worldwide by use of the right strategies and the best sales team. Currently Nestle is using the Hierarchical structure; the structure is great for organization that is located in different geographical locations. Though many companies are figuring out how to improve on the hierarchical structure or find better alternatives. Regardless of organization size, its more reliable to maintain managing of companies through the structure. Though the structure is resilient to management as most use it has become hard to find the better option.(NESTLE) Many challenges do exist in the use of the structure; communication usually flows from the top management to bottom. The structure makes it hard for innovation from top staff due less engagement from the lower level users leading to poor work relation as collaboration is usually nonexistent. The structure is usually riddled with and a lot of bureaucratic issues thus slow in decision making. This has made the hierarchy be on one of high vulnerable structures for NESTLE. Competitors can easily take over as they are usually no focus on employee experience. Maintaining top talent is also a threat as it renders most to stagnate at one position thus no space for growth.( Ulkuniemi and Seppnen ,2004) The best acquisition method for NESTLE accounting software is the purchase of a Commercial software .The software package which is available commercially usually satisfy the requirements of many organization. The advantages of the software package include lower costs, since many companies need software packages the development cost is usually spread across vendors since it is usually sold to large number of customers (Sean, 2009). Packages software have also been proven to offer reliability and better performance benchmarks as most defects are detected early through evaluation process. One is also assured of future upgrades from the vendor thus creating a better version. The defects are usually ironed out before the softwares is introduced in the market The sales procedures are described in three main steps: Visiting planning and preparation In store procedure? The system my fail to meet all requirements as they are not specific as to a tailor made software thus making it hard to process accounting problems that may have a greater negative impact to the organization. The system can be less efficient since it is usually designed for general (Ralf et al,2015).purposes making it less efficient. An example may be long process just to process a single transaction while some may have open ports that users arent aware for back roping by vendors References https://www.nestle.com.au/ Ralf Denzer, Robert M. Argent, Gerald Schimak, Ji? H?eb?ek,2015.Environmental Software Systems. Infrastructures, Services and Applications Sean Coleman , 2009.Open-source as an Alternative to Commercial Software Volume 583 of Final report (Arizona. Department of Transportation) Ulkuniemi P. and Seppnen V.2004, Management of COTS Software Component Acquisition in the Emerging Market, IEEE Software, 21, (6), 76-82.

The Rainmaker Persuasive Essay Example For Students

The Rainmaker Persuasive Essay The Rainmaker The world is full of great novels. From Sherlock Holmes to the threemusketeers. As the years progress more novels are written and moremoney is made. John Grisham is a rising star in literature. His bookshave enticed readers and has given the people something good to read. What makes his books great is that they are so realistic. He applies hispersonal law and trial knowledge into the books he writes. What it isabout ? It was his last semester of law school. Rudy Baylor wasassigned to give free advice to a group of seniors. It is at that very time,and that very place, that Rudy encounters his first true clients. Dot andBuddy Black. They have been robbed by a powerful insurance company. We will write a custom essay on The Rainmaker Persuasive specifically for you for only $16.38 $13.9/page Order now A company with millions of dollars in assets. They have caused thesuffering of a young man. They have ruined his chances to live by notissuing their coverage that they were obligated to give. Donny Ray, sonof Dot and Buddy is dying of Lukemia, he is going to die, his chancesfor survival are over and it is a matter of months. Rudy doesnt realizethe case that has fallen into his lap until phone calls are made. There is agreat problem, however, Rudy is broke, he hasnt even passed his barexam yet. And will go head to head with one of Americas mostexperienced and accomplished defense attorneys. From the beginningof the novel to the last word, Rudy is plagued with a series of mishapsand problems. When something looks bright the clouds come in and ruinthe hope. Rudy is in Luck. As the big trial begins, he is given a judgethat is definetly on his side and 12 jury members that think the same waythat he does. After researching great benefit, the insurance company,Rudy discovers cover ups by th e company. He also discovers GreatBenefits harsh way in getting rid of their numerous mistakes. n How itrelates to your audience The Trial Obviously Rudy is not stupid. Heenters all the facts he has discovered and uses them to help solidify hisposition in the minds of the jurors As the trial goes on Rudy is givenanother problem. A beaten girl is discovered by Rudy at the hospitalduring his studying. Her husband has repeatively beaten her with analuminum softball bat. Her ankle is broken and her life is in shreds. Rudy knows that these beatings will continue if the couple divorces butthe young girl of 18 is unable to leave because she believes that she isstill in love with him. n John Grisham does not maintain one singlestory, instead he creates numerous events so that the reader does not getbored with the main story. From minor cases to FBI investigations, JohnGrisham does a swell job in creating a global society. He shows thatlawyers have cares concerns about what is going on in the world andcontrary to popular belief, lawyers dont focus mainly on cases and theyhave lives to. Ever-since The Firm was published, in 1991, JohnGrisham has been in a creative state. His five books that followed thefirm, combine to form a total of approximately 50 million copies inprint. Why ? The answer is because his thrilling stories and intenselegal intrigue is in such a great demand. Now in The RainmakerGrisham has weaved his talent into the storyline and has created apowerful, and at times humerous , tale of one young lawyers quest forfame,fortune and most importantly, hapiness. I am positive that thisnovel will rise to the best sellers list, And after reading this book, youwill think alike. This novel is for all ages and all types. If the book youare searching for, is for excitement or pleasure. The Rainmaker is agreat novel and provides a goood read. John Grisham has done hishomework now do yours and read this good book. .uf114369ee172f2a0d3deb6f6b7699c34 , .uf114369ee172f2a0d3deb6f6b7699c34 .postImageUrl , .uf114369ee172f2a0d3deb6f6b7699c34 .centered-text-area { min-height: 80px; position: relative; } .uf114369ee172f2a0d3deb6f6b7699c34 , .uf114369ee172f2a0d3deb6f6b7699c34:hover , .uf114369ee172f2a0d3deb6f6b7699c34:visited , .uf114369ee172f2a0d3deb6f6b7699c34:active { border:0!important; } .uf114369ee172f2a0d3deb6f6b7699c34 .clearfix:after { content: ""; display: table; clear: both; } .uf114369ee172f2a0d3deb6f6b7699c34 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .uf114369ee172f2a0d3deb6f6b7699c34:active , .uf114369ee172f2a0d3deb6f6b7699c34:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .uf114369ee172f2a0d3deb6f6b7699c34 .centered-text-area { width: 100%; position: relative ; } .uf114369ee172f2a0d3deb6f6b7699c34 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .uf114369ee172f2a0d3deb6f6b7699c34 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .uf114369ee172f2a0d3deb6f6b7699c34 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .uf114369ee172f2a0d3deb6f6b7699c34:hover .ctaButton { background-color: #34495E!important; } .uf114369ee172f2a0d3deb6f6b7699c34 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .uf114369ee172f2a0d3deb6f6b7699c34 .uf114369ee172f2a0d3deb6f6b7699c34-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .uf114369ee172f2a0d3deb6f6b7699c34:after { content: ""; display: block; clear: both; } READ: Case Study Cameron Auto Parts EssayBibliographyThe Rainmaker, John Grisham.

The Flying Machine free essay sample

Also examined, are the ethics of intonating technological advancement and possible negative ramifications of technology evolving and therefore the loss of ultimate control over his empire. The emperor considers his empire to be beautiful when all is in order and his people are fully under his control. The flying machine exposes his vulnerability and puts his power at risk. These are some of the core ideas that The Flying Machine explores.Through the use and development of literary devices such as tone, diction, imagery, and very specific themes, Bradbury effectively displays the importance of the possible negative outcome of genealogy moving forward too quickly and resulting in risks to the Emperors empire. One of the themes of the story is the ethics around the creation of technology and the fear of change; the fear of change in technological advancement and the negative impact it could have on mankind and providing freedom. We will write a custom essay sample on The Flying Machine or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Towards the end of the story, the Emperor mentions he does not fear the creator of the flying machine, but rather another man with an evil face and an evil heart (Bradbury 4). He is afraid that another man will not see the beauty in what the inventor has created, but instead he will see it s an opportunity for corrupt and destructive plans such as the freedom to move outside the walls. If this invention were to allow people to leave the walls, the Emperors authority would be demolished. One of the important parts of being Emperor, is that he has control over everything within the wall. He thrives on being in charge and having control over all of his servants, and is of higher status than them. Perhaps, creating something of this level, without the permission of the Emperor, would give his people choices and allow them to be free. Allowing the inventor to have this flying machine would UT his power in jeopardy, and allow him to be vulnerable. He questions the flier of what he has done: What have you done? Demanded the Emperor. I have flown in the sky, Your Excellency, replied the man. What have you done? Said the Emperor again. l have just told you! cried the flier. You have told me nothing at all. (2) The inventor speaks in a very confident, but respectful tone, but is quite obviously proud of his creation. He does not realize the negative ramifications that his invention may have on the empire, he is just proud of the beauty in it. The Emperor tries to warn him that someone else may not see the beauty, but may use it for evil, but he does not understand, so he is executed so that no one will know of him or his invention.The story utilizes the term beauty and applies it to two different meanings; the raw beauty of a creation, to the flier, and the beauty of power, to the Emperor. A very important aspect of this story is the setting. Being set in ancient China, something like the flying machine would be considered a miracle (1), given the time. Being a country where all information is carefully controlled, meeting that showed innovation would be considered a threat.An invention such as this appearing in modern day would be notable, but would not be of the same level of significance as it is during an ancient and restrained period. Intricate and advanced technology did not exist at this point in time, causing the Emperor to immediately be cautious about the situation and aware of the danger that could be caused by someone thinking for himself and creating this invention. He is instantly defensive of the protected empire over which he rules. The diction used in this story is quite simple.None of the characters use overly complicated language, though they all speak in specific tones. These tones demonstrate the chain of command within the empire. The servant speaks with respect in his words: Please, said the servant at last, or he will be gone (1 The servant always speaks to the Emperor with respect because he is the head of the empire and the servant looks up to him. He never disrespects the Emperor because they are on two different levels of status. The flier speaks with words of confidence, because e only sees the beauty in his creation.He is proud of his machine: is the only one in the world! smiled the man. And I am the inventor m (2). He is blind to the idea of his device being used for evil. He is very confused when the Emperor instantly calls the guards to restrain him. Being overcome with the beautiful machine he made, he is not aware that he has overstepped his boundaries within this confined empire. The Emperor uses many literary devices to be descriptive in his language and to show his opinion of beauty. For instance, he uses imagery when ascribing his surroundings: Nanning himself against a warm breeze when a servant ran across the scarlet and blue garden tiles, (1). The story uses imagery in a way that allows the beauty of the empire to be imaginable. The Emperors real idea of beauty is revealed when he speaks of his own invention, a microcosm of his empire; the perfectly manipulated society. All of the animals moved as he thought they should and all of the people did what he wanted them to: Is it not beautiful? said the Emperor. If you asked me what I have done here, I could tell answer you well.I have made birds sing, I have made forests murmur, I have set people walking in his woodland, (3) His picturesque toy-like creation allows him to have full control over his empire, something he has created within the confines of the wall. When in this perfected world, he is never in a vulnerable position; he is always the highest power and has command of his people. In order to not be vulnerable, he says %.. One must lose a little beauty if one is to keep what little beauty one already has (3). This brings into question if the needs of many outweigh the deeds of few.The Emperors decision to execute the flier was based on his firm belief of protecting his people. The fliers invention could put the entire empire at risk by providing a means of escape, so, in the mind of the Emperor, it was the right decision. In this case, the Emperor was resolute in his choice, and is looking to protect his kingdom and the management of his people, described as beauty, which he has created with his empire. Having the flier and the flying machine around puts that at risk. In his mind, he needed to sacrifice one for the good of many.

VEGA Surname Origin and Last Name Meaning

VEGA Surname Origin and Last Name Meaning The Spanish surname Vega is a topographical name that means dweller in the meadow or one who lives on a plain, from the Spanish word  vega, used to refer to a meadow, valley or fertile plain. It could also be a habitational name for someone from one of any of the many places in the world named Vega or La Vega. Vega is the 49th most common Spanish surname. Alternate Surname Spellings: VEGAS, VEGAZ, DE LA VEGA,   Surname Origin: Spanish Where Do People With the VEGA Surname Live? The surname distribution map at Forebears, which includes data from 227 countries, pinpoints Vega as the 519th most common surname in the world. It identifies Vega as most common in Panama where it ranks 25th in the nation, followed by Puerto Rico (27th), Costa Rica (32nd), Peru (47th), Chile (47th), Argentina (50th), Mexico (55th), Spain (62nd), Cuba (74th), Equador (81st), Colombia (87th), Paraguay (96th) and Nicaragua (99th). WorldNames PublicProfiler identifies the Vega name in Spain as most frequently found in the northern regions of Asturias, Castille Y Leon, and Cantabria, as well as the southern regions of Andalucia and the Canary Islands. Within the United States, the Vega name is most common in the southwest, in the states bordering Mexico, along with Nevada, Idaho, and Florida, plus Illinois, New York, New Jersey, and Connecticut. Famous People with the VEGA Surname Paz Vega - Spanish actressAmelia Vega - 2003 Miss UniverseJurij Vega - Slovene mathematician and physicist- Spanish playwrightGarcilaso de la Vega - Spanish poet Genealogy Resources for the Surname VEGA 50 Most Common Spanish SurnamesHave you ever wondered about your Spanish last name and how it came to be? This article describes common Spanish naming patterns and explores the meaning and origins of 50 common Spanish surnames. Vega Family Crest - Its Not What You ThinkContrary to what you may hear, there is no such thing as a Vega family crest or coat of arms for the Vega surname.  Coats of arms are granted to individuals, not families, and may rightfully be used only by the uninterrupted male-line descendants of the person to whom the coat of arms was originally granted.   The Vega DNA Surname ProjectThis Y-DNA surname project is open to all  families with this surname, of all spelling variations, and from all locations, with the goal of using DNA matches to  help find the paper trail that leads further back up the Vega family tree. VEGA Family Genealogy ForumThis free message board is focused on descendants of Vega ancestors around the world. Search past queries, or post a question of your own. FamilySearch - VEGA GenealogyAccess over 1.7 million free historical records and lineage-linked family trees posted for the Vega surname and its variations on this free genealogy website hosted by the Church of Jesus Christ of Latter-day Saints. VEGA Surname Mailing ListThis free mailing list for researchers of the Vega surname and its variations includes subscription details and searchable archives of past messages. Hosted by RootsWeb. DistantCousin.com - VEGA Genealogy Family HistoryExplore free databases and genealogy links for the last name Vega. The Vega Genealogy and Family Tree PageBrowse family trees and links to genealogical and historical records for individuals with the last name Vega from the website of Genealogy Today. - References: Surname Meanings Origins Cottle, Basil. Penguin Dictionary of Surnames. Baltimore, MD: Penguin Books, 1967. Dorward, David. Scottish Surnames. Collins Celtic (Pocket edition), 1998. Fucilla, Joseph. Our Italian Surnames. Genealogical Publishing Company, 2003. Hanks, Patrick, and Flavia Hodges. A Dictionary of Surnames. Oxford University Press, 1989. Hanks, Patrick. Dictionary of American Family Names. Oxford University Press, 2003. Reaney, P.H. A Dictionary of English Surnames. Oxford University Press, 1997. Smith, Elsdon C. American Surnames. Genealogical Publishing Company, 1997. Back to Glossary of Surname Meanings Origins

Com 425 Week 4 Essay Example | Topics and Well Written Essays - 500 words

Com 425 Week 4 - Essay Example The arguments of the article may seem obvious, but the author has a point. Many people send and receive emails without prior consideration of who is being addressed. There is need to evaluate and assess all parties involved, appreciate their position within the business line and consequently address them accordingly. It is important to uphold mutual respect in such email exchanges. The tips provided seem obvious, but they are equally essential. The author of the article has identified mishaps in sending and receiving of emails between and among communicating parties. Some of the presented cases and points to remember are rather an application of mere common sense. However, the same points are hardly applied b senders and receivers of emails. The article may be analyzed for and against its arguments. Most of the tips however are sensible and should be observed when sending emails. Ignorance of such tips is likely to trigger misunderstandings or conflict of interest in business undertakings when the recipient gets different information from an email other than the one intended by the sender (Heather & Graves, 2011). The only tip that appears kind of absurd is that of watching one’s tone when composing an email. This is a hard to determine as the sender composes an email. Due to the ambiguity associated and brought about by the watch your tone tip, the author should have outlined a way through which email senders can evaluate the tone of their composed emails before sending them. The tip should have been elaborated and a guideline to determining one’s tone in writing provided. Computer-mediated communication is integral to almost every bit of sending and receiving information. Technological advancements have aided this process with computer communication making a contemporary mode of communication around the world. Knowledge and skills of computer use have highly increased.

Health Education and Promotion Models Assignment

Health Education and Promotion Models - Assignment Example On the contrary, the participatory design is aimed at creating successful community health promotion interventions. In addition, the Precede health promotion program planning model has eight phases as discussed. The first phase involves defining the ultimate outcome. It focuses on what the community wants and needs. It may seem unrelated to the issues of phase one. Phase two is for identifying the issue. In this phase, one looks for the issues and factors that might cause or influence the outcome identified in phase one. Phase three involves examining the factors that affect behaviour, lifestyle and responses to the environment. In this period, factors that will create the behaviour and environmental changes in phase two are. Step four identifies best practices and other sources of guidance for intervention design, as well as administrative, regulation and policy issues that influence the implementation of the program or intervention. Phase five is all about implantation. This step i nvolves doing just that setting up and implementing the interventions that have been planned for. Step six is for process evaluation. This phase is about the procedure but not results. Impact Evaluation is for stage 7. One begins by evaluating the initial success of the efforts. Step 8 is for Outcome Evaluation. The interventions must be working to bring about the outcomes the community identified in step 1.Proceed health promotion planning model has four assumptions. In this model, it’s assumed that health and other issues are essentially quality-of-life issues. It that health and other issues must be looked at in the context of the community. Health is also a constellation of factors that add up to a healthy life for individuals and communities. It that behaviour change is by and large voluntary, health promotion, is more likely to be effective if it’s participatory (Green and Kreuter2005). Health belief model is also a

NETWORKING SKILLS FOR THE CREATIVE INDUSTRIES Essay

NETWORKING SKILLS FOR THE CREATIVE INDUSTRIES - Essay Example Through such a discussion and analysis, it is the hope of this particular author that the reader will gain a more informed understanding with respect to the necessity and importance of networking as well as a further understanding and identification of the ways in which a focus upon networking can help to build the prospects in the future of the individual that engages with it. Section 1: Firstly, even though it is true that this skill and knowledge learned in a formalized educational setting is not in and of itself sufficient for each and every situation, it should not be understood that networking is a skill that does not require teaching and is somehow innate within each and every human being. Due to differentials of personal psychology, many individuals are introverts whereas others tend to be more extroverted (Calin & Mcgee, 2006). However, even though a personal psychological approach to networking is necessary, should also be understood that even the most introverted individua l can utilize effective networking within their own life and professional career as a means of maximizing the benefit that they would otherwise achieved in and of themselves (Jain, 2011). In seeking to define what networking is, it should be understood that whereas many terms require a broad and complicated explanation, networking is fairly simple. Ultimately, this process can be understood based upon the realization that networking is a process through which an individual can leverage personal and business connections as a means of gaining valuable information that they can then apply towards increasing profitability, client base, efficiency or other positive business engagements (Sharafizad, 2011). As such, the obvious point that should be understood is with respect to the fact that networking allows for an individual to not only leveraging utilize the information that they have been presented or come in contact with, it also allows for a shared collective of knowledge and informa tion to be passed along from one individual, or group of individuals, to another. Although this is not a difficult concept to grasp, it should be understood that the bulk of the education process, from kindergarten all the way to postgraduate work, is concentric upon the degree and extent to which information can be retained at a personal level (Kokkonen et al., 2013). Although it is true that outside research is oftentimes required, collaborative in group effort is not common and therefore is not necessarily a tactic that the recently graduated business man or woman would otherwise engage in. As such, even though this process is extraordinarily simple and easy to engage in, a great many young professionals, and professionals of any age for that matter, necessarily choose to rely upon their own abilities as this is a thought process and means of engagement that has become solidified as a result of many years of education. From a strategic standpoint, the process of

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

Dropping of the Droppings on Hiroshima and Nagasaki

In 1945, following the ending of World War II in Europe, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki, thereby ending World War II with Japan as well. This event has been controversial to the present day. With this controversy in mind, this research will analyze several aspects of this pivotal event in world history. Why Did the United States Decide to Drop the Bombs?Essentially, the US decided to drop the bombs on Hiroshima and Nagasaki not because of a lust for blood or an ego trip on the part of president Harry S. Truman, but simply because Japan held a mindset of victory or death. For Japan, that meant that if it was not possible to defeat the US in the war, the Japanese would kill as many American soldiers as possible. This was achieved through the massive deployment of the kamikaze, suicide warriors who would fly their aircraft into American warships, strap explosives to their bodies and tackle American soldiers, or employ any number o f other suicide techniques in order to kill US troops (Newman, 1995).Therefore, Truman chose to use the atomic bomb in an ironic way to save many more lives in the long term by using one powerful weapon to blast the Japanese into submission. Results of the Event on the United States and the World For the US, the dropping of the atomic bomb sent a powerful message to the rest of the world that this nation would not be intimidated or tolerate any aggression against it. The dropping of the atomic bomb meant years of painful physical and mental effects for the Japanese people.For the world, this pivotal event signaled the beginning of a nuclear arms race, which erupts in some ways to this day. Conclusion What is seen in the tale of Hiroshima and Nagasaki, in conclusion are lessons about the price of war, the quest for healing, and the realization that nuclear war is an option that must be carefully considered, lest it become too common a solution for the problems of the world. Works Cit ed Newman, R. P. (1995). Truman and the Hiroshima Cult. East Lansing, MI: Michigan State University Press.