機(jī)械專業(yè)畢業(yè)設(shè)計--外文資料和翻譯

1、<p>　　Metal heat treatment</p><p>　　A, annealing</p><p>　　In front of the description lengba processing materials and softening plastic treatment methods, it has been used the word, the wor

2、d annealing with similar meanings. The purpose is to reduce completely annealing, hardness, plastic, sometimes also increased to improve the cutting performance, high this steel is difficult to processing. This method is

3、 used to reduce heat stress, refined grains, improve the structure of the material.</p><p>　　Annealing is not always can improve the cutting machining, cutting processing a word used to describe several fact

4、ors, including material cutting when good finish (i.e. smaller surface roughness - the ability of the translator. When fully annealing, ordinary low hardness, low intensity of cutting resistance smaller, less, but usuall

5、y due to the plasticity and toughness is too big to chip away when the surface of workpiece surface of workpiece surface quality, scratch, leads to poor cutting proce</p><p>　　And the annealing method is Gon

6、gXi just slow to the steel wire, insulation above about for a period of time, make the same temperature uniformity, forming materials, then the austenitic or buried with furnace lime or other insulating materials in slow

7、 cooling. To precipitation of ferrite and pearlite bulky iron, steel in the soft, the strain of toughness and minimum, must slow cooling.</p><p>　　Second, normalizing</p><p>　　How much is the fi

8、re of similar purposes, but not the annealing steel soft and fine pearlite state. Not bulky. Steel is refined grains, fire can release of stress, improve structural homogeneity and restore some plastic, high toughness. T

9、his method is often used to improve cutting machining, reduce stress, reduce part machining or limitation of deformation.</p><p>　　Is the fire will chromatography method is GuoGongXiGang steel or slow heated

10、 to Ac3 respectively, Accm line or on-line insulation for a period of time to form, and in the austenitic stationary air slow cooling. Should notice more, GongXi composition of carbon steel needs to be heated to Accm lin

11、e above, not Ac1 line above the annealing. The purpose is in the process of austenitic to dissolve all cementite, thus to minimize the boundaries on hard and brittle iron carbon compounds, and get little </p><

12、p>　　Third, the ball annealing</p><p>　　Through the steel ball annealing can get minimum hardness and the biggest plastic, it can make the iron carbon compounds with small globular distribution in ferritic

13、 matrix. In order to make the ball easier small particles, usually for fire steel ball annealing. Ball annealing available in several different methods, but all the methods are needed in A1 line near (usually slightly lo

14、w temperature preservation) for a long time, make the iron carbon compounds formed more stable, low level of small </p><p>　　Ball annealing method of the main objective is to improve the cutting processing,

15、and drawing of hardened steel pretreatment, make it more uniform structure quenching. Because of the heat treatment for a long time, so the cost is higher than that of ball annealing is common or annealing.</p>&l

16、t;p>　　Four, steel sclerosis</p><p>　　The most hardened steel heat treatment method is based on the production of martensite high. Therefore, the first step to most other treatment with commonly used metho

17、d -- austenitic. YaGongXiGang heated to Ac1 liquidus temperature, heat preservation, more about that temperature uniformly, austenitic evenly. GuoGongXiGang Ac1 above liquidus temperature preservation in steel, while abo

18、ut still remain iron carbon compounds.</p><p>　　The second step is to avoid rapid cooling in the nose produces isothermal curve transformation pearlite. The cooling speed depends on the temperature and harde

19、ned steel quenching medium heat can be taken away from the surface of the ability of heat transfer and steel itself. Table 1-11 is some common medium and cooling method, cooling ability of the sequence.</p><p&

20、gt;　　High temperature gradient produces high stress, deformation and cracking causes, so only in the very need to produce quenching specific structures are used. When the quenching heat uniform, care must be taken to red

21、uce the heat stress diffusion. For example, a thin stick to end its vertical quenching, is inserted into the cooling medium, so whole section and temperature changes. If the shape of a side of the workpiece cooling, and

22、on the other side of the earlier than size change is likely to ca</p><p>　　With several special quenching method can reduce stress, deformation and cracking quenching decreases. One called hierarchical quenc

23、hing, the method is: will the austenitic steel in temperature is higher than that of martensite transformation temperature (Ms), salt bath time until the temperature uniformity, at the beginning of forming bainite, then

24、put before air cooling, heat generated from the start when the same hardware quenching cracking, martensite and warpage cause of high thermal stress</p><p>　　In a similar method of temperature, then, is call

25、ed the isothermal quenching (austenitic steel in salt bath), keep for a long time, the result is formed with the isothermal bainite. Bainite structure in the same ingredients as the formation of martensite hard, but in n

26、ormal hardened steel, reduce the heat shock, by further processing, unnecessary in high hardness can be obtained when good impact toughness.</p><p>　　Five, tempering</p><p>　　To adjust hardened

27、steel used the third step is often backfire. Besides the isothermal quenching steel quenching condition usually used in most all can use in production. To produce martensite steel to quench make hard, macro and micro str

28、ess, stress, low plasticity materials. To reduce the harm that can be heated to steel again by low-temperature shift (A1) below a certain temperature. Hardened steel structure change of tempering time and temperature is

29、the function of temperature, which is the</p><p>　　The structural change and tempering causes change depending on performance of the heating temperature steel back. The higher the temperature, the temperatur

30、e effect, so the choice is often sacrificed for the hardness and strength plasticity and toughness. Again, to quench heating to influence of carbon-steel, in between, structure, changes will occur in the above, the struc

31、ture and properties of the significant changes. In the next time the temperature of the A1 heat will produce and process of </p><p>　　In industry, usually avoid to scope, because the tempering within the sco

32、pe of tempering steel often produced unexplained brittleness or plastic loss. Some alloy in to scope, also can produce "temper brittleness, especially from" (or by) the temperature range slow cooling will appea

33、r. When these steel heat temper, they must usually heated to rapid cooling and above. Of course, from the temperature of cold won't produce sclerosis, fast because no austenitic.</p><p><b>　　金屬熱處理&

34、lt;/b></p><p><b>　　一、退火</b></p><p>　　在前面描述冷拔加工材料的軟化并重新獲得塑性的熱處理方法時，就已使用退火這個詞，該詞具有相似的意義。完全退火的目的是降低硬度、增加塑性，有時也提高高碳鋼的切削性能，否則這種鋼很難加工。這種熱處理方法也用來減少應(yīng)力，細(xì)化晶粒，提高整個材料的結(jié)構(gòu)均勻性。</p><p&

35、gt;　　退火不總是能提高切削加工性，切削加工性一詞用來描述幾個相關(guān)因素，包括材料切削時獲得好的光潔度（即較小的表面粗糙度——譯者）的能力。當(dāng)完全退火時，普通低碳鋼硬度較低，強(qiáng)度較小，對切削的阻力較小，但通常由于塑性和韌性太大以至切屑離開工件表面時會劃傷表面，工件表面質(zhì)量比較差，導(dǎo)致較差的切削加工性。對這類鋼，退火可能不是最合適的處理方法。許多高碳鋼和大多數(shù)合金鋼的切削加工性通?？山?jīng)退火大大改善，因為除在最軟條件下，它們的硬度和強(qiáng)度太高

36、而不宜加工。</p><p>　　亞共析剛的退火方法是將鋼緩慢加熱到線以上大約，保溫一段時間，使整個材料溫度相同，形成均勻奧氏體，然后隨爐或埋在石灰或其它絕緣材料中緩慢冷卻。要析出粗大鐵素體和珠光體，使鋼處于最軟、最韌和應(yīng)變最小的狀態(tài)，必須緩慢冷卻。</p><p><b>　　二、正火</b></p><p>　　正火的目的多少類似于退火，但

37、鋼不是最軟狀態(tài)且珠光體是細(xì)勻而不粗大。鋼的正火能細(xì)化晶粒，釋放內(nèi)應(yīng)力，改善結(jié)構(gòu)均勻性同時恢復(fù)一些塑性，得到高的韌性。這種方法經(jīng)常用來改進(jìn)切削加工性，減少應(yīng)力，減少因部分切削加工或時效產(chǎn)生的變形。</p><p>　　正火方法是將亞析鋼或過共析鋼分別緩慢加熱到Ac3線或Accm線上約，保溫一段時間以便形成奧氏體，并在靜止空氣中緩冷。要注意，含碳量超過共析成分的鋼要加熱到Accm線以上，而不是退火時的Ac1線以上。正

38、火的目的是在奧氏體化過程中試圖溶解所有滲碳體，從而盡可能減少晶界上的硬脆鐵碳化合物，而得到小晶粒的細(xì)珠光體、最小自由鐵素體和自由滲碳體。</p><p><b>　　三、球化退火</b></p><p>　　通過球化退火可使鋼得到最小的硬度和最大的塑性，它可使鐵碳化合物以小球狀分布在鐵素體基體上。為了使小顆粒球化更容易，通常對正火鋼進(jìn)行球化退火。球化退火可用幾種不同的

39、方法，但所有方法都需要在A1線溫度附近（通常略低）保溫很長時間，使鐵碳化合物形成更穩(wěn)定，能級較低的小圓球。</p><p>　　球化退火方法的主要目的是改進(jìn)高碳鋼的切削加工性，并對淬硬鋼進(jìn)行預(yù)處理，使其淬火后結(jié)構(gòu)更均勻。因為熱處理時間長，因此成本高，球化退火不如退火或正火常用。</p><p><b>　　四、鋼的硬化</b></p><p>

40、　　鋼的大多數(shù)熱處理硬化方法是基于產(chǎn)生高比例的馬氏體。因此，第一步用的似乎大多數(shù)其他熱處理常用的方法——產(chǎn)生奧氏體。亞共析鋼加熱到Ac1線溫度以上大約，進(jìn)行保溫，使溫度均布，奧氏體均勻。過共析鋼Ac1線溫度以上大約時保溫，鋼中仍殘留部分鐵碳化合物。</p><p>　　第二步是快速冷卻，力圖避免在等溫曲線鼻部產(chǎn)生珠光體轉(zhuǎn)變。冷卻速度取決于溫度和淬火時淬火介質(zhì)從鋼表面帶走熱量的能力以及鋼本身傳熱的能力。表11-1是

41、一些常用介質(zhì)和冷卻方法，按冷卻能力降低的順序排列。</p><p>　　高的溫度梯度產(chǎn)生高應(yīng)力，會引起變形和開裂，所以淬火只有在非常需要產(chǎn)生特定結(jié)構(gòu)時才使用。淬火時必須小心，使熱量均勻擴(kuò)散以減少熱應(yīng)力。比如，一根細(xì)長棒需端部淬火，即將它垂直插進(jìn)冷卻介質(zhì)中，這樣整個截面同時產(chǎn)生溫度變化。如果這種形狀的工件的某一邊比另一邊早降溫，尺寸變化很可能引起很高的應(yīng)力，產(chǎn)生塑性流動和永久變形。</p><p

42、>　　用幾種特殊的淬火方法可減小淬火應(yīng)力，減小變形開裂傾向。一中稱為分級淬火，其方法是：將奧氏體鋼放入溫度高于馬氏體轉(zhuǎn)變起始溫度（Ms）的鹽浴中，放置一定的時間直到溫度均勻，在開始形成貝氏體之前取出，然后放在空氣中冷卻，產(chǎn)生與從高溫開始淬火時同樣硬的馬氏體，而導(dǎo)致開裂和翹曲的高的熱應(yīng)力或淬火應(yīng)力已經(jīng)被消除。</p><p>　　在略高一點溫度下的類似方法稱為等溫淬火，這時，將（奧氏體）鋼放在鹽浴中，保持很長

43、時間，等溫處理的結(jié)果是形成貝氏體。貝氏體結(jié)構(gòu)不如在同樣成分時形成的馬氏體硬，但除了減少鋼在正常淬火時受到的熱沖擊外，不必要進(jìn)一步處理，就可獲得在高硬度時好的沖擊韌性。</p><p><b>　　五、回火</b></p><p>　　調(diào)整淬硬鋼以便使用的第三步通常是回火。除了等溫淬火鋼通常在淬火狀態(tài)下使用外，大多數(shù)鋼都不能在淬火狀態(tài)下使用。為產(chǎn)生馬氏體而采取的激冷使鋼

44、很硬，產(chǎn)生宏觀內(nèi)應(yīng)力和微觀內(nèi)應(yīng)力，使材料塑性很低，脆性極大。為減少這種危害，可通過將鋼再加熱到A1線（低溫轉(zhuǎn)變）以下某一溫度。淬火鋼回火時產(chǎn)生的結(jié)構(gòu)變化是時間和溫度的函數(shù)，其中溫度是最重要的。必須要強(qiáng)調(diào)，回火不是硬化方法，而是剛好相反。回火鋼是將經(jīng)熱處理硬化的鋼，通過回火時的再加熱，來釋放應(yīng)力、軟化和提高塑性。</p><p>　　回火引起的結(jié)構(gòu)變化和性能改變?nèi)Q于鋼重新加熱的溫度。溫度越高，效果越大，所以溫度的

45、選擇通常取決于犧牲硬度和強(qiáng)度換取塑性和韌性的程度。重新加熱到以下，對淬火普碳鋼影響不大，在到之間，結(jié)構(gòu)會發(fā)生某些變化，在以上，結(jié)構(gòu)和性能顯著變化。在緊靠著A1溫度以下的長時間加熱會產(chǎn)生與球化退火過程類似的球化結(jié)構(gòu)。</p><p>　　在工業(yè)上，通常要避免在到范圍內(nèi)回火，因為這個范圍內(nèi)回火的鋼經(jīng)常會產(chǎn)生無法解釋的脆性或塑性喪失現(xiàn)象。一些合金鋼在到范圍內(nèi)，也會產(chǎn)生“回火脆性”，特別是從（或通過）這個溫度范圍緩慢冷卻