机械工程专业英语课件--L08.ppt

1、机械工程专业英语,课文分析,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,课文分析,上述考虑因素提供了锻造温度系列的分

3、类基础，换句话说，分热加工（热锻）和冷加工（冷锻）。,The above considerations provide the basis for classification of forging temperature ranges, namely, hot working (hot forging) and cold working (cold forging).,在再结晶温度以上才能完成塑性变形加工的就是热加工。,n.再结晶,Lesson 8 Cold Working and Hot Working,Hot working is considered to be plastic def

4、ormation that is accomplished above the recrystallization temperature.,课文分析,使用“热加工”这一术语通常意味着材料一般要加热，但并不总是要加热。例如，铅的再结晶就是在很低的温度下进行。,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.,根据以上定义，在室温条件下铅的锻造也是热加工。,Lesson 8 Cold Working and Hot Working,By the above definition, lead forged at room temperature is being hot worked.,机械工程专业英语,课文分析,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,课文分析,在再结晶温度以下的塑性变形被

7、定义为冷加工。,Cold working is defined as plastic deformation below the recrystallization temperature.,几种常用金属或他们的合金，其再结晶温度大约在750C900C,大约, 约等于,Lesson 8 Cold Working and Hot Working,Several common metals, or their alloys, have recrystallization temperatures in the order of 750C900C.,课文分析,为了改善性能，这些合金中的某些合金是在5

8、50C700C温度范围内通过锻造来进行硬化处理的。,To improve properties, several of these alloys are strain hardened by forging in the range of 550C700C.,尽管按照定义，这确实是“冷加工”，但它常常被称作是“热加工”。,Lesson 8 Cold Working and Hot Working,Although by definition, this is truly “cold work”, it is often referred to as “warm work”.,机械工程专业英语,

9、课文分析,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,机械工程专业英语,课文分析,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.,如果材料性质最终要获得改善，就必须非常严密地控制所谓“热加工”操作。,加热主要是为了减少流动应力，进而减少所需的锻造力。,机械工程专业英语,课文分析,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.,对于奥氏体不锈钢、高温合金钢和许多有色金属合金的再结晶温度可在超出相当大的范围内变化。,实行以上操作工艺之后接着就要在低于锻造温度以下的温度中进行消除应力处理。,机械工程专业英语,课文分析,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,影响再结晶温度的因素包括：目前的应变硬化程度、退火时间，变形前的晶粒度，以及固溶体中溶质原子的浓度。,knsentrein n. 集中， 专心 化提浓,浓缩,浓度； 采矿汰选 集中物， 密集,机械工程专业英语,课文分析,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.,在再结晶瞬间，再结晶晶粒度与变形程度成反比。,这一事实导致依靠控制再结晶和控制变形的相结合来使晶粒晶粒

16、度细化的可能。,prp:nladj. 比例的, 成比例的,机械工程专业英语,课文分析,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,机械工程专业英语,课文分析,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.,借助控制变形使晶粒粒度细化在锻造实践中是常有的事。,然而，这种方法本身也存在危险。,机械工程专业英语,课文分析,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,几乎所有的合金对于应变硬化与温度都很敏感，此时会出现晶粒迅速长大的现象（称为非正常晶粒长大）。,机械工程专业英语,课文分析,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,该结果通常称为临界应变而且通常是在该合金处于相对而言小的变形时发生，尽管这多少取决于变形前的晶粒粒度和合金种类。,机械工程专业英语,课文分析,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