制造技术专业英语翻译.docx

1、制造技术专业英语翻译7.1 NATURE OF PLASTIC DEFORMATIONPlastic deformation is the deformation which is permanent and beyond the elastic rang of the material of ten , metals are worked by pfastic deformation because of the beneficial effect that is imparted to the mechanical properties by it. The necessary defor

2、mation in a metal can be achieved by application of large amount of mechanical force only or by heating the metal and then applying a small force.7.1 塑性变形本质塑性变形是超过弹性变形范围之后的一种永久变形。通常，金属采用塑性变形加工是因为可以通过其获得良好的机械性能。金属所需要的变形可以只通过施加大量的机械力或者通过加热金属并且施加少量的应力来获得。The deformation of metals, which is caused by th

3、e displacement of the atoms is achieved by one or both of the processes called slip and twinning. The details of the microscopic deformation methods can be found in the textbooks of metallurgy. On the macroscopic scale, when plastic , deformation occurs the metal appears to flow in the solid state a

4、long specific directions, which are depedent on the type of processing and the direction of applied force. The crystals or grains of the metal are elongated in the direction of metal flow. This flow of metal can be seen under microscope after polishing and suitable etching of the mental surface . Th

5、ese visible lines are called fibre flow lines, some representative specimens of which are presented in fig 金属的变形是由原子排列引起的，这种排列是由被称作滑移和孪生过程中的一种或者两者共同作用造成的。微观的变形方式可以从冶金学课本中找到。在微观范围内，当塑性变形产生的时候，在固体内部金属的流动倾向于特定的方向，这个方向取决于加工类型和应力方向。在金属流动方向上金属晶体或者晶粒将会延长。通过显微镜观察抛光和蚀刻后的表面，可以看到这种金属的流动方式。这些可见的线条叫做纤维流线。Since t

6、he grains are elongated in the direction of flow, whey would be able to offer more resistance to stresses acting across them . As a result, the mechanically worked metals called wrought products would be able to achieve better mechanical strength in specific orientation ,that of the flow direction .

7、since it is possible sible to control these flow lines in any specific direction by careful manipulation of the applied forces as shown in Fig. 7.1, it is possible to achieve optimum mechanical properties. The metal, of course, would be weak along the flow lines.因为晶粒在流动方向上被拉长了，这样他们就更能够抵抗作用于其上的应力。因此，

8、在被称为锻造产品的机械加工零件的金属流动方向上会获得优良的强度。这是因为，只要小心谨慎地控制应力，就能让纤维流线朝着任何一个方向流动并且获得最佳的机械性能。当然，金属在沿着纤维线的方向也会变得疲软。The wastage of material in metal-working processes is either negligible or very small, and the production rate is in general very high .these two factors give rise to the economy in production材料的浪费在金属加

9、工过程中是很少的，甚至可以忽略不计，并且其生产率一般来说是非常高的。这两个因素使其在生产上更为经济。7.1.1 Hot Working and Cold WorkingThe metal-working processes are traditionally divided into hot -working and cold-working processes. The division is on the basis of the amount of heating applied to the metal before applying the mechanical force.7.1.

10、1 冷加工和热加工传统的金属加工工艺分为热加工和冷加工。这种区分是基于机械应力施加前金属的受热程度。Those processes , working above the recrystallization temperature, are termed hot-working processes whereas those below are termed cold-working processes在这些加工工艺中，加热温度在再结晶温度以上的叫做热加工，在再结晶温度以下的叫做冷加工。Under the action of heat and force when the atoms reac

11、h a certain higher energy level, the new crystals start forming which is termed as recrystallization . Recrystallization destroys the old grain structure deformed by mechanical working and entirely new crystals, which are strain-free are formed, the grains, in fact ,start nucleating at the points of

12、 severest deformation. Recrystallzation temperature as defined by the American Society of Metals is “ the approximate minimum temperature at which complete recrystallization of a coldworked metal occurs within a specified time ”.在加热和应力的作用下，当原子达到某一更高能量的等级的时候，新的晶粒就开始形成的过程叫做再结晶。再结晶破坏了由机械作用构成的原有晶体结构，并且产

13、生了无应变的新的晶体。事实上，新的晶粒是在严重变形的时候开始形核的。再结晶温度是由美国金属学会这样定义的“在一定的时间段内，冷加工金属完成再结晶时的最小温度”。The recrystallization temperature generally varies between one-third to half the melting point of most of the metals. Typical values of recrystallisation temperatures are given in table 7.1,the recrystallization temperat

14、ure also depends on the amount of cold work a material has already received. the higher the cold work the lower would the recrystallization temperature as shown in Fig 7.2大多数的金属再结晶温度一般在金属熔点的三分之一到二分之一内。表7.1给出了具有代表性的再结晶温度值。再结晶温度取决于材料已经改变的冷加工量。冷加工量越高，再结晶温度越低，如图7.2所示。In hot working, the process may be c

15、arried above the recrystallization temperature with or without actual heating.For example,for lead and tin,the recrystallization temperature is below the room temperature and hence working of these metals at room temperature is always hot working.Similarly for steels,the recrystallization temperatur

16、e is of the order of 1000,and therefore working below that temperature is still cold working only.在热加工中，在加热或者不加热的实际条件下再结晶可能在再结晶温度以上发生。例如，铅和锡，它们的再结晶温度都在室温以下，所以室温下的加工都属于热加工。同样，钢也是一样的，钢的再结晶温度达到1000摄氏度，因此，在这温度以下的加工都是冷加工。In hot working.,the temperature at which the working is completed is important since

17、 any extra heat left after working will aid in the grain growth,thus giving poor mechanical properties.The effect of temperature of completion of hot working is shown schematically in simple heating is shown in A,where the grains start growing after the metal size would be larger than when started i

18、n A.After heating,when the metal is worked,because of recrystallization,the grain size is reduced.This is made of possible because the working of metal gives rise to a large number of nucleation sites for the new crystals to form.But if the hot working is completed much above the recrystallization t

19、emperature as in.C,the grain size starts increasing and finally may end up as a coarse grain size.This increase in size of the grains occurs by a process of coalescence of adjoining grains and is a function of time and temperature.This is not generally desirable.If the hot working is completed just

20、above the recrystallization temperature as in D then the resultant grain size would be fine.The same is schematically shown for hot rolling operation in 在热加工中，加工完成后的温度是很重要的，因为加工完成后任何余热都能让晶粒长大，这样会得到很差的机械性能。热加工最后温度的影响如图表7.3。如A中的一个简单加热过程，当温度超过再结晶温度后，晶粒就开始长大。当在没有热加工的条件下冷却时，如B，晶粒最后的尺寸将会比A开始的时候大。加热之后，由于再结

21、晶作用，当金属加工的时，晶粒尺寸就会减小。金属的加工将会增加在大量的形核点形成新核的可能性。但是，热加工的最后温度比再结晶温度高太多的话，如C,晶粒的尺寸就开始增大并且最后会得到粗大的晶粒尺寸。晶粒的尺寸的增大是通过合并相邻晶粒的过程发生的，这是时间和温度相互作用的结果。一般情况下，这都不是我们想要的。如果热加工的最终温度在再结晶温度以上，如D，这样得到的细小的晶粒尺寸。HOT Working Advantages1. As the material is above the recrystallization temperature,any amount of workingcan be i

22、mparted since there is no strain-hardening taking place.2. At a high temperature,the material would have higher amount of ductility andtherefore there is no limit on the amount of hot working that can be done on a material.Even brittle material can be hot worked.3. Since the shear stress gets reduce

23、d at higher temperatures,hot working requiresmuch less force to achieve the necessary deformation.热加工益处1. 当材料温度在再结晶温度以上时，加工量的多少都是可以的，因为这时候没有加工硬化的产生。2. 在较高温度下，材料将会有较高的韧性，因此材料的热变形量没有限制。即使脆性材料也可以进行热加工。3. 因为在较高温度下剪切应力将会减小，热加工中少量的应力就能获得所需的变形。4. 热加工中，晶粒的继续改良是有可能的，如果温度和加工率得到适当的控制，将会获得优良的晶粒尺寸和良好的机械性能。Disadv

24、antages1.Some metals cannot be hot worked because of their brittleness at high temperatures.2.Higher temperatures of metal give rise to scaling of the surface and as a result,the surface finish obtained is poor.Also,there is a possibility of the decarburization of skin in steels due to the high temp

25、erature.3.Because of the thermal expansion of metals,the dimensional accuracy in hot working is hart to achieve since it is difficult to control the temperature of workpieces.4.Handling and maintaining of hot metal is difficult and troublesome.弊处1. 由于在较高温度下材料脆性的原因，一些金属不能进行热加工。2. 高温下，金属表面比例将会增大，这样将会导

26、致最后得到的表面质量很差。而且，由于高温会使钢表面有脱碳的可能性。3. 由于金属内热扩散的原因，控制工件的温度是很困难的，所以在热加工中很难获得精确的尺寸。4. 操作和维持加热金属是很困难和麻烦的。Cold working advantages1. Cold working increases the strength and hardness of the material due to strain hardening which would be beneficial in some situation.Table 7.3 gives some comparative values fo

27、r t he properties obtained after hot working and cold working.Further,there is no possibility of decarburization of the surface.2. Since the working is due in the cold tate,no oxide would form on the surface and conseque ntly,good surface finish obtained.3. Better dimensional accuracy is achieved.4

28、It is far easier to handle cold parts and also is economical for smaller size. 冷加工益处1. 由于加工硬化的原因，冷加工将会增加材料的强度和硬度，这在某些方面是有利的。图表7.3给出了热加工和冷加工后获得的性能的一些比较值。而且，冷加工不会有表面脱碳的可能性。2. 因为加工是在冷态下完成的，所以表面不会产生氧化物，最后会得到良好的表面质量。3. 能获得良好的尺寸精确性。较小尺寸的冷态零件更容易控制，而且也很经济Disadvantages1.Since the material has higher yield st

29、rength at lower temperatures,the amount of deformation that can be given to is limited by the capability of the presses or hammers used.2.Since the material gets strain hardened,the maximum amount of deformation that can be given is limited.Any further deformation can be given after annealing.3.Some

30、 materials which are brittle cannot be cold worked.弊处1. 因为低温下材料拥有较高的屈服强度，所以变形量将会受到压力机和锤头能力的限制。2. 因为加工硬化的原因，最大变形量也会受到限制，任何后续的变形都需经过退火。 一些脆性材料不能进行冷加工。7.2.1 PrincipleRolling is a process where the metal is compressed between two rotating rolls for reducing its cross-sectional area.This is one of most w

31、idely used of all the metal working processes,because of its higher productivity and low cost.Rolling would be able to produce components having constant cross section throughout its length.many shapes such as I,T,L and channel sections are possible as shown in fig.7.6,but not very complex shapes.It

32、 is also possible to produce special sections such as railway wagon wheels by rolling individual pieces.7.2 辊轧辊轧是在两根旋转辊之间对金属施加压力使其横截面积减少的一种工艺。由于较高的生产率和较低的花费使其广泛应用于各种金属加工工艺。辊轧可以生产在沿长度方向上拥有恒定截零件。如图7.6是中的I、T、L和槽型等许多形状，但是不能生产复杂的形状。它也可以通过辊轧单独的零件来制造特定截面的零件，如铁路货车车轮。Rolling is normally a hot-working process unless specifically mentioned as cold rolling.The metal is taken into rolls by friction and subsequently compressed to obtain the finial shape.The thickness of the metal that can be drawn into rolls depend on the roughness of the roll surface.Rough