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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,word,availability,可用性,veilbiliti,fabrication,制造,fbrikein,forgeability,可锻性,f:dblt,nickle,鎳,nikl,chromium,铬,kroumjm,vanadium,钒,vneidim,discernible,可辨别得出的,；,可看出的,disnbl,ductility,延,(,展,),性,；,韧性,dktiliti,cracking,开裂,；,裂纹,krki,Selection of Construction Materials,1,wordavailability 可用性veil,word,Work-harden,加工硬化,；,冷作硬化,anneal,退火,ni:l,warp,翘曲,；,变形,w:rp,preheat,预热,prihit,microstructure,显微结构,makrostrkt,mislead,使,误解；误导,msli:d,ream,铰孔,rim,arbitrary,任意的,:rbitrri,Selection of Construction Materials,2,wordWork-harden 加工硬化；冷作硬化 S,Selection of Construction Materials,There is not a great difference between“this”steel and“that”steel;all are very similar in mechanical properties.,在钢之间没有太大的区别；所有的钢在机械性能方面都是近似的。,3,Selection of Construction Mate,Selection of Construction Materials,Selection must be made on factors such as,hardenability,price,and,availability,and not with the idea that“this”steel can do something no other can do because it contains 2 percent instead of 1 percent of a certain alloying element,or because it has a,mysterious,mistiris name.,它们的选取标准是诸如,脆硬性,，,价格,，和,可用性,等。不仅仅是因为这种钢含有,2,的合金元素另一种钢含有,1,而使前者具有了后者没有的某些能力，或者是某种钢具有,神奇的,名字。,4,Selection of Construction Mate,Selection of Construction Materials,A,tremendous range,of properties is available in any steel after,heat treatment,;this is particularly true of alloy steels.,经过,热处理,后，任何一种钢都具有,大范围,的特性；这种性质同样在合金钢中存在。,5,Selection of Construction Mate,Considerations in fabrication,The properties of the final part(,hardness,strength,and,machinability,),rather than properties required by,forging,govern,the selection of material.,最后零件的特性（,硬度,、,强度,和,可加工性,）而不是,锻造,特性,决定,了材料的选择。,6,Considerations in fabricationT,Considerations in fabrication,The properties required for forging have very little relation to the final properties of the material;therefore,not much can be done to improve its,forgeability,.,可锻性与材料的最后特性联系不大；因此，提高金属的,可锻造性,价值不大。,Higher-carbon steel is difficult to forge.Large grain size is best if,subsequent,heat treatment will refine the grain size.,高碳钢很难锻造。如果,后续的,热处理会细化晶粒尺寸，那么大的晶粒尺寸是最好的。,7,Considerations in fabricationT,Considerations in fabrication,Low-carbon,nickel-chromium steels,are just about as plastic at high temperature under a single 520-ftlb(1 ftlb=1.35582J)blow as plain steels of similar carbon content.Nickel decreases,forgeability,of medium-carbon steels,but has little effect on low-carbon steels.,在高温下低碳，,镍铬合金钢,在受到,520-ftlb,的冲击下表现出与相同碳含量普通钢几乎同样的塑性。镍减少了中碳钢的,可锻性,，但对低碳钢影响不大。,8,Considerations in fabricationL,Considerations in fabrication,Chromium,seems to harden steel at forging temperatures,but,vanadium,has no,discernible,effect;neither has the method of manufacture any effect on high-carbon steel.,铬,在锻造温度下时使钢硬化，但,钒,没有,明显的,效果；两种加工方法对高碳钢没有影响。,9,Considerations in fabricationC,Formability,The cold-formability of steel is a function,of its,tensile strength,combined with ductility.The tensile strength and,yield point,must not be high or too much work will be required in,bending,;,likewise,the steel must have sufficient,ductility to flow to the required shape without cracking.,钢的冷成形是它的,拉伸强度,和延展性相结合的结果。拉伸强度和,屈服点,不能太高否则在发生,弯曲,时需要做很多工作；相似,地,，钢应该有高延展性，使其在没断裂的情况下成形。,10,FormabilityThe cold-formabilit,Formability,The force required depends on the yield point,because deformation starts in the plastic range above the yield point of steel.Work-hardening also occurs here,progressively,stiffening,the metal and causing difficulty,particularly,in the low-carbon steels.,加工力的大小取决于屈服点，因为钢在屈服点之上才开始变形。与此同时，加工硬化也同时发生，金属变得,越来越硬,，增加加工难度，尤其在低碳钢中容易发生。,11,FormabilityThe force required,Formability,It is quite interesting in this connection,to discover that deep draws can sometimes be made in one rapid operation that could not possibly be done,leisurely,leli,in two or three.,在这方面，相当有趣的是你将发现有时可通过一次快速加载完成大拉伸，但以,缓慢的,方式两三次加载却不能实现。,12,FormabilityIt is quite interes,Formability,If a draw is half made and then stopped,it may be necessary to,anneal,before proceeding,that is,if the,piece,is given time to work-harden.This may not be a scientific statement,but it is actually what seems to happen.,如果拉伸进行了一半就停止了，那么在再加工之前应先,退火,，也就是说，,如果,工件,已经,有时间,被,加工硬化。这不是一种科学的叙述方法，但确实是发生了。,13,FormabilityIf a draw is half m,Internal stresses,Cold forming is done above the yield point in the work-hardening range,so internal stresses can be built up easily.Evidence of this is the,springback,as the work leaves the forming operation and the,warpage,in any,subsequent heat treatment.,在高于屈服点的加工硬化区进行冷加工很容易产生内应力。例如工件停止成型加工后会发生,回弹,，在随后的热处理后，工件会发生,翘曲,。,14,Internal stressesCold forming,Internal stresses,Even a simple washer might,by virtue of the internal stresses resulting from punching,and then flattening,warp,severely,during heat treating.,即使是一个简单的垫圈，由于打孔和随后的平整加工中产生内应力，也会在热处理中呈现严重的翘曲。,15,Internal stressesEven a simple,Internal stresses,When doubt exists as to,whether internal stresses will cause warpage,a piece can be checked by heating it to about 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