材料成型及控制工程專業(yè)英語 2 HEAT TREATMENT OF STEEL綜述

1、 2009 ? Hisuntech Corp. 材料成型專業(yè)英語第二章 上海工程技術(shù)大學(xué) 材料學(xué)院 CHAPTER 2 HEAT TREATMENT OF STEEL 熱處理在現(xiàn)代機(jī)械工程中的作用不可能 評(píng)價(jià)的過高。由熱處理而產(chǎn)生的性能改變是特別 重要的。 - 1 - ? The role of heat treatment in modern mechanical engineering can not be overestimated . ? The changes in the properties of metals due to heat treatment are of extre

2、mely great significance . CHAPTER 2 HEAT TREATMENT OF STEEL ?2.1.1 temperature and time 溫度和時(shí)間 - 2 - ? 任何熱處理的目的都是（ 通過）將金屬加熱到一定的溫度并 (隨后)冷卻,以使金屬組織產(chǎn)生所需變化。 The purpose of any heat treating process is to produce the desired changes in the structure of metal by heating to a specified temperature and by sub

3、sequent cooling. CHAPTER 2 HEAT TREATMENT OF STEEL ?2.1.1溫度和時(shí)間 - 3 - ? 因此，熱處理的主要因素是溫度和時(shí)間， 所以任何熱處理工藝都以用溫度-時(shí)間為坐標(biāo)軸進(jìn)行表示。 Therefore, the main factors acting in heat treatment are temperature and time, so that any process of heat treatment can be represented in temperature-time ( t- r ) coordinates. 2.1.1

4、 temperature and time 溫度和時(shí)間 ?熱處理工藝主要有以下幾個(gè)參數(shù)：加熱溫度 tmax ，既合金加熱的最高溫度；在加熱溫度下的 保溫時(shí)間；加熱速率和冷卻速率。 - 4 - ? Heat treatment conditions are characterized by the following parameters: heating temperature tmax, i.e. the maximum temperature to which an alloy metal is heated; time of holding at the heating temperat

5、ure ; heating rate and cooling rate . ? 2.1.1 temperature and time 溫度和時(shí)間 ?如果以不變速率加熱或冷卻，則溫度和時(shí)間的關(guān)系可以具有不同傾斜角的直線。 - 5 - ? If heating (or cooling) is made at a constant rate, the temperature-time relationship will be described by a straight line with a respective angle of incline . ? Respective分別的, 各自的 2

6、.1.1 temperature and time 溫度和時(shí)間 ?如果加熱速率（或冷卻速率）變化，則 實(shí)際速率由給定溫度確定，更嚴(yán)格的說，是溫度對(duì)時(shí)間的 無窮變化：即溫度對(duì)時(shí)間的一階導(dǎo)數(shù)。 - 6 - ? With a varying heating ( or cooling) rate. the actual rate should be attributed to the given temperature ,more strictly, to an infinite change of temperature and time: that is the first derivative

7、of temperature in time . ? Infinite 無限的東西(如空間、時(shí)間), 數(shù)無窮大 2.1.1 temperature and time 溫度和時(shí)間 ?加熱可以是復(fù)雜的過程，可以包括幾個(gè)加熱階段、間斷式或階梯式的加熱/冷卻，冷卻到0以下等。任何熱處理過程都可以描述成為以溫度和時(shí)間為坐標(biāo)軸的曲線。 - 7 - ? Heat treatment may be a complex process, including multiple heating stages . interrupted or stepwise heating ( cooling) , cooling

8、 to subzero temperatures, etc . Any process of heat treatment can he described by a diagram in temperature-time coordinates . ? interrupt 中斷stepwise樓梯式的, 逐步的subzero- 零度以下的（溫度） 2.1.2 formation of austenite 2.1.2 formation of austenite - 8 - - 8 - 根據(jù)Fe-C相圖，在平衡臨界點(diǎn)緩慢加熱，珠光體轉(zhuǎn)變?yōu)閵W氏體。一般條件下，轉(zhuǎn)變會(huì)延遲導(dǎo)致 guore，即轉(zhuǎn)變溫

9、度略高于 Fe-C相圖中的指定溫度。 ? The transformation of pearlite into austenite can only take place at the equilibrium critical point on a very slow heating as follows from the Fe-C constitutional diagram. Under common conditions, the transformation is retarded and results in overheating, i. e. occurs at tempera

10、tures slightly higher than those indicated in the Fe-C diagram. ? Constitutional diagram相圖(構(gòu)成的, 增強(qiáng)體質(zhì)的, 憲法的）pearlite 珠光體 retard 延遲, 使減速, 阻止, 妨礙, 阻礙 2.1.2 formation of austenite ?當(dāng)加熱溫度高于臨界點(diǎn)時(shí)，珠光體轉(zhuǎn)變?yōu)閵W氏體， 轉(zhuǎn)變速率依賴于過熱的程度。 (過熱、過冷的概念 ) - 9 - ? When overheated above the critical point, pearlite transform into

11、austenite， the rate of transformation being dependent on the degree of overheating . 2.1.2 formation of austenite ?各溫度下的轉(zhuǎn)變時(shí)間（依賴于過熱度）表明在較高的溫度下相變產(chǎn)生較快（時(shí)間短）；加熱速度快時(shí)，相變?cè)谳^高溫度產(chǎn)生。 - 10 - ? The time of transformation at various temperatures (depending on the degree of overeating) shows that the transformation

12、 takes place faster (in a shorter time) at a higher temperature and occurs at a higher temperature on a quicker heating . 2.1.2 formation of austenite ?例如，780加熱速度較快時(shí)，珠光體完全轉(zhuǎn)變?yōu)閵W氏體需要2分鐘，740時(shí)則需要8分鐘。 - 11 - ? For instance, on quick heating and holding at 780，the pearlite to austenite transformation is co

13、mpleted in 2 minutes and on holding at 740C, in 8 minutes . ? centigrade 2.1.2 formation of austenite - 12 - ? 轉(zhuǎn)變結(jié)束是以奧氏體形成和珠光體 (F+滲碳體)消失為標(biāo)記的。然而，即使在單個(gè) 晶粒中奧氏體的也不均勻。 ? The end of the transformation is characterized by formation of austenite and the disappearance of pearlite ( ferrite +cementite) . This

14、 austenite is however inhomogeneous even in the volume of a single grain . 2.1.2 formation of austenite - 13 - ? 早期形成的片狀(或li狀)珠光體滲碳體，其含碳量高于片狀鐵素體，這就是奧氏體（成分）不均勻的原因。 ? lamellae薄片狀的, 薄層狀的 ? In places earlier occupied by lamellae (or grains) of a pearlitic cementite, the content of carbon is greater than

15、 in places of ferritic lamellae . This is why the austenite just formed is inhomogeneous . 2.1.2 formation of austenite ?為了獲得均勻的奧氏體，加熱溫度不僅要超過珠光體轉(zhuǎn)變?yōu)閵W氏體的終點(diǎn)溫度，而且要高于這一溫度，并保溫一段時(shí)間，使奧氏體晶粒內(nèi)發(fā)生完全 擴(kuò)散。 - 14 - ? In order to obtain homogeneous austenite, it is essential on heating not only to pass through the poi

16、nt of the end of pearlite to austenite transformation, but also to overheat the steel above that point and to allow a holding time to complete the diffusion processes in austenitic grains - 15 - ? 奧氏體均勻化的速度主要依賴與鋼的原始組織，特別是 滲碳體的分布及晶粒形狀。當(dāng)滲碳體顆粒 細(xì)小均勻，總表面積較大時(shí)，相轉(zhuǎn)變更快。 ? The rate of homogenization of austeni

17、te appreciably depends on the original structure of the steel, in particular on the dispersion and particle shape of cementite . The transformations described occur more quickly when cementite particles are fine and, therefore ,have a large total surface area . ? Particle 粒子, 點(diǎn), 極小量, 微粒 ? Appreciabl

18、y 1.有一點(diǎn)兒的; 可以感到的; 2.可觀的, 值得重視的 2.1.2 formation of austenite 2.1.3Coarsening of Austenite Grains ?在珠光體向奧氏體轉(zhuǎn)變開始時(shí)，奧氏體首先在鐵素體和滲碳體（珠光體的組織組分）之間的晶界處形成。因?yàn)榫Ы绶浅６嘁虼宿D(zhuǎn)變首先形成于大量的細(xì)小晶粒。 ?developed 發(fā)達(dá)的，引申為“多”。 - 16 - ? At the beginning of pearlite to austenite transformation. The first grains of austenite form at the

19、boundaries between the ferrite and cementite the two structural constituents of pearlite. Since these boundaries are very developed, the transformation starts from formation of a multitude of fine grains. Coarsening of Austenite Grains ?因此，奧氏體轉(zhuǎn)變結(jié)束時(shí)，會(huì)形成大量的細(xì)小晶粒，它們的尺寸稱之為 奧氏體初始晶粒度 。 - 17 - ? Therefore,

20、at the end of the transformation the austenite will be composed of a great multitude of fine grains whose size characterizes what is called the original austenite grain size. ?隨著加熱(保溫)溫度高于轉(zhuǎn)變溫度，將引起奧氏體晶粒的粗化。晶粒粗化的過程是 自發(fā)的，因?yàn)榫Я？偯娣e減少（表面能減少）和高溫可以 加速轉(zhuǎn)變過程 。 - 18 - ? Further heating ( or holding) upon the tra

21、nsformation will cause coarsening of austenitic grains. The process of grain coarsening is spontaneous , since the total surface area of grains diminishes ( the surface energy decreases) and a high temperature can only accelerate the rate of this process. ?in that connection 在那種情況下, 如果情況是那樣liability

22、 、liable有責(zé)任的, 有義務(wù)的, 易.的, 有.傾向的, inherent 固有的, 內(nèi)在的, 與生俱來的 ?在那種情況下，就可以形成兩種鋼： 固有細(xì)晶粒(鋼)和固有粗晶粒(鋼) 。前者晶粒粗化的傾向比 后者小。鋼中通過熱處理形成的晶粒尺寸稱之為 實(shí)際晶粒度。 - 19 - ? In that connection , two types of steels are distinguished: inherent fine grained and inherent coarse grained, the former being less liable to grain coarseni

23、ng than the latter . The size of grains formed in a steel by heat treatment is called the actual grain size . ?因此，區(qū)分如下： (1)原始晶粒度，即珠光體剛轉(zhuǎn)變?yōu)閵W氏體時(shí)奧氏體的晶粒尺寸； (2)固有晶粒度，即奧氏體粗化的傾向性； (3)實(shí)際晶粒度，也就是在給定條件下的奧氏體實(shí)際晶粒尺寸。 - 20 - ? Thus , a distinction should be made between: (1) original grain , i.e. the size of austen

24、itic grains immediately after the pearlite to austenite transformation; (2) inherent ( natural) grain, i.e. the liability of austenite to grain coarsening; and (3) actual grain , i.e. the size of austenitic grains under given particular conditions. 2.1.3 Coarsening of Austenite Grains 2.1.3 Coarseni

25、ng of Austenite Grains - 21 - - 21 - 奧氏體轉(zhuǎn)變?yōu)橹楣怏w時(shí)珠光體晶粒的大小決定于奧氏體形成時(shí)的晶粒大小。奧氏體僅在加熱時(shí)長(zhǎng)大（冷卻時(shí)不細(xì)化），因?yàn)閵W氏體區(qū)的最高溫度和固有晶粒度決定了最終晶粒尺寸。 ? The size of pearlitic grains at same temperature of the austenite to pearlite transformation depends on that of the austenitic grains from which they have formed. Austenitic grains

26、grow only during heating ( but are not refined in subsequent cooling), because of which the highest temperature a steel is heated to in the austenitic state and the inherent grain size of that steel determine the final grain size. 2.1.3 Coarsening of Austenite Grains 2.1.3 Coarsening of Austenite Gr

27、ains - 22 - - 22 - 鋼的性能僅僅由最終晶粒大小而不是固有晶粒大小決定。具有相同等級(jí)的兩種鋼 (一是固有粗晶粒，另一是細(xì)晶粒 )根據(jù)不容溫度的熱處理，將有相同的實(shí)際晶粒尺寸，它們的性質(zhì)也將相同。否則，兩種鋼的許多性能將不同。 ? The properties of a steel are affected only by the actual grain size and not by the inherent grain size. If two steels of the same grade (one inherently coarse grained, the othe

28、r fine grained) have the same actual grain size upon heat treatment at different temperatures, their properties will also be the same; if otherwise , many properties of the two steels will also be different. 2.1.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 23 - - 23 - ? 奧氏體向珠光體轉(zhuǎn)變本

29、質(zhì)是奧氏體分解為近乎純的鐵素體和滲碳體。 ? The austenite to pearlite transformation is essentially the decomposition of austenite into almost pure ferrite and cementite. 2.1.4 decomposition of Austenite 2.1.4 decomposition of Austenite - 24 - - 24 - 在平衡溫度時(shí)，不發(fā)生轉(zhuǎn)變，因?yàn)槌跏紛W氏體的自由能等于最終產(chǎn)物珠光體的自由能。 ? At the equilibrium temperatur

30、e, the transformation is impossible, since the free energy of the original austenite is equal to that of the final product, pearlite. 2.1.4 decomposition of Austenite 2.1.4 decomposition of Austenite - 25 - - 25 - 只有珠光體(鐵素體和碳化物的混合物 )的自由能低于奧氏體，在一定的過冷度下，轉(zhuǎn)變才發(fā)生。 ? The transformation can only start at a

31、certain undercooling when the free energy of the ferrite carbide mixture (pearlite) is lower than that of austenite. - 26 - - 26 - 轉(zhuǎn)變溫度越低、過冷度越大，自由能差越大，轉(zhuǎn)變速度越快。 ? The lower the transformation temperature, the higher the degree of undercooling and the greater the difference in free energies and the tra

32、nsformation proceeds at a higher rate. 2.1.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 27 - 在珠光體轉(zhuǎn)變中，新相的成分與原始相完全不同，鐵素體幾乎不含碳，滲碳體含碳6.67。， ? in the pearlite transformation, the new phase sharply differ in their composition from the initial phase; they are ferrite which is almost free

33、 of carbon , and cementite which contains 6.67 percent carbon. 2.1.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 28 - - 28 - 因此奧氏體轉(zhuǎn)變?yōu)橹楣怏w伴隨著碳的擴(kuò)散和重新分布。隨著溫度的降低，擴(kuò)散率顯著降低，因此，轉(zhuǎn)變需在較高的過冷下，轉(zhuǎn)變會(huì)被延遲。 ? For this reason the austenite to pearlite transformation is accompanied with the diffusion, r

34、edistribution of carbon. The rate of diffusion sharply diminishes with decreasing temperature, therefore, the transformation should be retarded at a greater undercooling. 2.1.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 29 - - 29 - 因此，可得出一重要結(jié)論：過冷（較低的轉(zhuǎn)變溫度）對(duì)轉(zhuǎn)變速率可以產(chǎn)生兩種相反的影響。 ? thus,

35、we have come to an important conclusion that undercooling (lowering the transformation temperature) may have two opposite effects on the rate of transformation. 2.1.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 30 - 一方面，溫度較低，過冷較大，使奧氏體和珠光體自由能差較大，因此加速相變，另一方面，它降低了碳擴(kuò)散的速率，又減慢了相轉(zhuǎn)變。 ? On

36、one hand , a lower temperature (greater undercooling ) gives a greater difference in free energy of austenite and pearlite, thus accelerating the transformation; on the other hand , it diminishes the rate of carbon diffusion, and thus slows down the transformation. 2.1.4 Decomposition of Austenite -

37、 31 - - 31 - 整個(gè)影響就是：隨著過冷度的增加，轉(zhuǎn)變率增加到某一最大值后，隨著進(jìn)一步的過冷而降低. ? The combined effect is that the rate of transformation first increase as undercooling is increased to a certain maximum and then decreases with further undercooling. 2.1.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 32 - - 32

38、 - 在727和低于200時(shí)，轉(zhuǎn)變率為0，因?yàn)?27時(shí)自由能差為0，低于200時(shí)，C的擴(kuò)散率為0.（更嚴(yán)格的來講，溫度太低，轉(zhuǎn)變難以進(jìn)行。） ? at 727 (A1) and below 200 , the rate of transformations is zero, since at 727 the free energy difference is zero and below 200 the rate of carbon diffusion is zero (more strictly, too low for the transformation to proceed). 2.1

39、.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 33 - 珠光體的形成是珠光體形核和珠光體晶粒長(zhǎng)大的過程， 這一點(diǎn)首先由I.L.Mirkin 在1939年提出，并由R.F.Mehl 在1941年加以完善。 ? As has been first indicated by I.L.Mirkin in 1939 and then developed by R.F.Mehl in 1941, the formation of pearlite is the process of nucleation of pearli

40、te and growth of pearlitic crystals. 2.1.4 Decomposition of Austenite - 34 - - 34 - 因此，在不同過冷程度下珠光體的轉(zhuǎn)變速率不同 ,(這)主要是因?yàn)檫^冷度影響形核率 N和晶核長(zhǎng)大速率G。在A1和200以下，N和G都等于0，并在在150200時(shí)過冷度最大. ? Therefore, the different rate of the pearlite transformation at various degrees of undercooling is due to the fact that undercool

41、ing differently affects the rate of nucleation N and the rate of crystal growth G. At temperature A1 and below 200 , both parameters of crystallization N and G are equal to zero and have a maximum at an undercooling of 150200. 2.1.4 Decomposition of Austenite 2.1.4 Decomposition of Austenite - 35 -

42、如前所述如前所述，當(dāng)條件允許，例如奧氏體過冷到 A1點(diǎn)以下，C的擴(kuò)散速率不為0，則產(chǎn)生形核中心，繼而形成晶粒。隨時(shí)間變化產(chǎn)生的這一過程可用 動(dòng)力學(xué)轉(zhuǎn)變曲線 表示，該曲線中會(huì)顯示從轉(zhuǎn)變開始后，隨時(shí)間變化，珠光體的形成量。 ? It follows from the forgoing that as soon as the conditions are favorable, i.e. austenite is undercolled below A1, the diffusion of carbon is not zero, centers of crystallization appear, w

43、hich give rise to crystals. This process occurs with time and can be represented in the form of so called kinetic curve of transformation, which shows the quantity of pearlite that has formed during the time elapsed from the beginning of the transformation. 2.1.4 Decomposition of Austenite - 36 - -

44、36 - 初始階段，轉(zhuǎn)變速率非常慢，稱之為 孕育期。轉(zhuǎn)變進(jìn)程中，速率加快，當(dāng)大約有 50% 的奧氏體轉(zhuǎn)變?yōu)橹楣怏w時(shí)，轉(zhuǎn)變速率達(dá)到最大。然后轉(zhuǎn)變速率減小并停止。 ? The initial stage is characterized by a very low rate of transformation; this is what is called incubation period . The rate of transformation increases with progress in the transformation. Its maximum approximately co

45、rresponds to the moment when roughly 50 percent of austenite has transformed into pearlie. The rate of transformation then diminishes and finally stops. 2.1.4 Decomposition of Austenite - 37 - 轉(zhuǎn)變速率依賴于過冷度，過冷度過低和過高都使轉(zhuǎn)變進(jìn)程變慢，這是由于N、G比較小，前者是由于自由能差過低，后者是因?yàn)樵訑U(kuò)散慢，在轉(zhuǎn)變速率最大處，動(dòng)力學(xué)曲線上有 峰值，在較短的時(shí)間間隔里，轉(zhuǎn)變結(jié)束。 ? The rat

46、e of transformation depends on undercooling. At low and high degrees of undercooling the transformation proceeds slowly, since N and G are low: in the former case, owing to a low difference in free energy, and in the later , due to a low diffusion mobility of atoms. At the maximum rate of transforma

47、tion the kinetic curves have sharp peaks, and the transformation is finished in a short time interval. 2.1.4 Decomposition of Austenite - 38 - - 38 - 在高溫時(shí)（即過冷度?。D(zhuǎn)變速度慢， 孕育期和完全轉(zhuǎn)變的時(shí)間較長(zhǎng)，在較低的溫度轉(zhuǎn)變，及過冷度較大，轉(zhuǎn)變速率變大，轉(zhuǎn)變時(shí)間和孕育期較短。 ? At a high temperature (slightly undercooling), the transformation proceeds slowl

48、y and the incubation period and the time of the transformation proper are long. At a lower temperature of the transformation, i.e. a deeper undercooling, the rate of transformation is greater, and the time of the incubation period and of the transformation is shorter. 2.1.4 Decomposition of Austenit

49、e 2.1.4 Decomposition of Austenite - 40 - 已經(jīng)確定了奧氏體想珠光體轉(zhuǎn)變開始的時(shí)間（ 孕育期）和各種過冷度下轉(zhuǎn)變結(jié)束的時(shí)間，我們可以繪制一幅圖， 圖左邊的曲線代表轉(zhuǎn)變開始的時(shí)間，即：過冷態(tài)下，奧氏體仍然存在的 時(shí)間，從縱坐標(biāo)軸到曲線的部分來度量其（奧氏體）的 穩(wěn)定性。 ? Having determined the time of the beginning of austenite to pearlite transformation ( incubation period ) and the time of the end of transforma

50、tion at various degrees of undercooling , we can construct a diagram in which the left hand curve determines the time of the beginning of the transformation, i.e. the time during which austenite still exists in the undercooling state, and the section from the axis of ordinates to the curve is the me

51、asure of its stability. 2.1.5 TTT Diagram or C-Curve - 41 - - 41 - 在溫度500600 時(shí)，這部分區(qū)間最短，即：在此溫度下轉(zhuǎn)變?cè)谧疃虝r(shí)間內(nèi)開始。 ? This section is shortest at a temperature of 500600 , i.e. the transformation begins in a shortest time at that temperature. 2.1.5 TTT Diagram or C-Curve - 42 - - 42 - 右邊曲線表示在給定過冷度下，完全轉(zhuǎn)變所需的時(shí)間，

52、這時(shí)在同一溫度下（500600 ）所用時(shí)間最短。 注意圖中的橫坐標(biāo)是對(duì)數(shù)形式。這樣做是為了更 方便，因?yàn)橹楣怏w形成速率明顯不同（在臨界點(diǎn)A1點(diǎn)附近為上千秒，在曲線彎曲處只要一兩秒。） ? The right hand-curve shows the time needed to complete the transformation at a given degree of undercolling. This time is the shortest at the same temperature (500600 ). Note that the abscissa of the diagra

53、m is logarithmic . This is done for more convenience, since the rates of formation of pearlite appreciably differ ( thousands of seconds near the critical point A1 and only one or two seconds at the bend of the curve). 2.1.5 TTT Diagram or C-Curve - 43 - - 43 - 圖中曲線下的水平線代表無擴(kuò)散馬氏體轉(zhuǎn)變溫度，馬氏體有不同的轉(zhuǎn)變機(jī)制，稍后討論

54、。 ? The horizontal line below the curves in the diagram determines the temperature of the diffusionless matensite transformation. The martensite transformation occurs by a different mechanism and will be discussed later. 2.1.5 TTT Diagram or C-Curve - 44 - - 44 - 我們討論的圖通常稱為TTT（時(shí)間溫度轉(zhuǎn)變）圖，或者C曲線，這主要因?yàn)榍€

55、特殊的形狀。奧氏體分解產(chǎn)物的組織和性能取決于轉(zhuǎn)變發(fā)生的溫度。 ? Diagrams of the type we discussed are usually called TTT diagrams ( time temperature transformation), or C curve, owing to the specific shape of the curves, the structure and properties of the products of austenite decomposition depends on the temperature at which the transformation has taken place. 2.1.5 TTT Diagram or C-Curve - 45 - - 45 - 高溫時(shí)，即：過冷度小，形成鐵素體和滲碳體混合的粗大晶粒，這可以在顯微鏡下區(qū)分。這種組織稱為珠光體。 ? At high temperatures, i.e. low degrees of undercooling, a coarse grained mixture of ferrite and cementite is formed which is e