1、機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,The above considerations provide the basis for classification of forging temperature ranges, namely, hot working (hot forging) and cold working (cold forging). Hot working is considered to be plastic deformation that is accomplished above the recrystallization temperature. The use of t

2、he term “hot working” usually implies that the material is heatedbut not always. For example, the recrystallization of lead takes place at very low temperatures. By the above definition, lead forged at room temperature is being hot worked.,Lesson 8 Cold Working and Hot Working,課文分析,上述考慮因素提供了鍛造溫度系列的分

3、類(lèi)基礎(chǔ)，換句話說(shuō)，分熱加工（熱鍛）和冷加工（冷鍛）。,The above considerations provide the basis for classification of forging temperature ranges, namely, hot working (hot forging) and cold working (cold forging).,在再結(jié)晶溫度以上才能完成塑性變形加工的就是熱加工。,n.再結(jié)晶,Lesson 8 Cold Working and Hot Working,Hot working is considered to be plastic def

4、ormation that is accomplished above the recrystallization temperature.,課文分析,使用“熱加工”這一術(shù)語(yǔ)通常意味著材料一般要加熱，但并不總是要加熱。例如，鉛的再結(jié)晶就是在很低的溫度下進(jìn)行。,The use of the term “hot working” usually implies that the material is heatedbut not always. For example, the recrystallization of lead takes place at very low temperatur

5、es.,根據(jù)以上定義，在室溫條件下鉛的鍛造也是熱加工。,Lesson 8 Cold Working and Hot Working,By the above definition, lead forged at room temperature is being hot worked.,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,Cold working is defined as plastic deformation below the recrystallization temperature. Several common metals, or their alloys, have recrystal

6、lization temperatures in the order of 750C900C. To improve properties, several of these alloys are strain hardened by forging in the range of 550C700C. Although by definition, this is truly “cold work”, it is often referred to as “warm work”.,Lesson 8 Cold Working and Hot Working,課文分析,在再結(jié)晶溫度以下的塑性變形被

7、定義為冷加工。,Cold working is defined as plastic deformation below the recrystallization temperature.,幾種常用金屬或他們的合金，其再結(jié)晶溫度大約在750C900C,大約, 約等于,Lesson 8 Cold Working and Hot Working,Several common metals, or their alloys, have recrystallization temperatures in the order of 750C900C.,課文分析,為了改善性能，這些合金中的某些合金是在5

8、50C700C溫度范圍內(nèi)通過(guò)鍛造來(lái)進(jìn)行硬化處理的。,To improve properties, several of these alloys are strain hardened by forging in the range of 550C700C.,盡管按照定義，這確實(shí)是“冷加工”，但它常常被稱(chēng)作是“熱加工”。,Lesson 8 Cold Working and Hot Working,Although by definition, this is truly “cold work”, it is often referred to as “warm work”.,機(jī)械工程專(zhuān)業(yè)英語(yǔ),

9、課文分析,The heating is done mainly to reduce the flow stress and thereby the forging force required. “Warm working” operations must be very closely controlled if the ultimate improvement in properties is to be obtained. The operation is normally followed by stress relieving at a temperature below the t

10、emperature. The temperature of recrystallization for austenitic stainless steels, higher temperature alloys, and many non-ferrous alloys can vary over a considerable range. Factors influencing this temperature include the degree of strain hardening present, the time of annealing, the prior grain siz

11、e and the solute atomic concentration in solid solution.,Lesson 8 Cold Working and Hot Working,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,The heating is done mainly to reduce the flow stress and thereby the forging force required.,Lesson 8 Cold Working and Hot Working,“Warm working” operations must be very closely controlled if

12、 the ultimate improvement in properties is to be obtained.,如果材料性質(zhì)最終要獲得改善，就必須非常嚴(yán)密地控制所謂“熱加工”操作。,加熱主要是為了減少流動(dòng)應(yīng)力，進(jìn)而減少所需的鍛造力。,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,The operation is normally followed by stress relieving at a temperature below the forging temperature.,Lesson 8 Cold Working and Hot Working,The temperature of recrys

13、tallization for austenitic stainless steels, higher temperature alloys, and many non-ferrous alloys can vary over a considerable range.,對(duì)于奧氏體不銹鋼、高溫合金鋼和許多有色金屬合金的再結(jié)晶溫度可在超出相當(dāng)大的范圍內(nèi)變化。,實(shí)行以上操作工藝之后接著就要在低于鍛造溫度以下的溫度中進(jìn)行消除應(yīng)力處理。,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,Factors influencing this temperature include the degree of strain har

14、dening present, the time of annealing, the prior grain size and the solute atomic concentration in solid solution.,Lesson 8 Cold Working and Hot Working,影響再結(jié)晶溫度的因素包括：目前的應(yīng)變硬化程度、退火時(shí)間，變形前的晶粒度，以及固溶體中溶質(zhì)原子的濃度。,knsentrein n. 集中， 專(zhuān)心 化提濃,濃縮,濃度； 采礦汰選 集中物， 密集,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,The recrystallized grain size at the

15、instant of recrystallization is inversely proportional to the degree of deformation.,Lesson 8 Cold Working and Hot Working,This fact leads to the possibility of grain size refinement by a combination of controlled deformation and recrystallization.,在再結(jié)晶瞬間，再結(jié)晶晶粒度與變形程度成反比。,這一事實(shí)導(dǎo)致依靠控制再結(jié)晶和控制變形的相結(jié)合來(lái)使晶粒晶粒

16、度細(xì)化的可能。,prp:nladj. 比例的, 成比例的,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,Refinement of grain size by means of controlled deformation is regularly practiced by the forging industry. However, there is hazard inherent to this method. Nearly all the alloys are sensitive to a combination of strain hardening and temperature where very

17、 rapid grain growth (called “abnormal grain growth”) occurs. The combination is normally referred to as critical strain and usually occurs when the alloy is subjected to relatively small strains, although this is somewhat dependent on the prior grain size as well as the alloy.,Lesson 8 Cold Working

18、and Hot Working,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,Refinement of grain size by means of controlled deformation is regularly practiced by the forging industry.,Lesson 8 Cold Working and Hot Working,However, there is hazard inherent to this method.,借助控制變形使晶粒粒度細(xì)化在鍛造實(shí)踐中是常有的事。,然而，這種方法本身也存在危險(xiǎn)。,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,Nearly all the all

19、oys are sensitive to a combination of strain hardening and temperature where very rapid grain growth (called “abnormal grain growth”) occurs.,Lesson 8 Cold Working and Hot Working,幾乎所有的合金對(duì)于應(yīng)變硬化與溫度都很敏感，此時(shí)會(huì)出現(xiàn)晶粒迅速長(zhǎng)大的現(xiàn)象（稱(chēng)為非正常晶粒長(zhǎng)大）。,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,The combination is normally referred to as critical strain

20、 and usually occurs when the alloy is subjected to relatively small strains, although this is somewhat dependent on the prior grain size as well as the alloy.,Lesson 8 Cold Working and Hot Working,該結(jié)果通常稱(chēng)為臨界應(yīng)變而且通常是在該合金處于相對(duì)而言小的變形時(shí)發(fā)生，盡管這多少取決于變形前的晶粒粒度和合金種類(lèi)。,機(jī)械工程專(zhuān)業(yè)英語(yǔ),課文分析,Controlling grain size by recrystallization is not merely a matter of imparting strain hardening and recrystallization. The critical zone must be avoided by straining either more or less than the critical amount. The location of the critical one is of key importance and unfortu