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1、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,word,Work-harden 加工硬化；冷作硬化 anneal 退火 ni:l warp 翘曲；
2、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,Selection of Construction Materials,There is not a great difference between “this” steel and “that” steel; all are very similar in mechanical proper
3、ties. 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 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 alloyin
4、g 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 Materials,A tremendous range of properties is available in any steel after heat treatment; this is particularly true of alloy steels. 经过
5、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,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 fabrication,The propertie
6、s 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 gr
7、ain 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 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 ste
8、els, 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 fabrication,Chromium seems to harden steel at forging temperatures, but vanadium has no discernible effect; neither has the method of manufacture any effect on h
9、igh-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,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 suffic
10、ient 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,Formability,The force required depends on the yield point, because deformation starts in the plastic range above the yield point of steel. Work-hardening al
11、so 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,Formability,It is quite interesting in this connection to discover that deep draws can sometimes be made in one
12、 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,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 no
13、t 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,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
14、 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 stresses,Even a simple washer might, by virtue of the internal stresses resulting from punching and then flattening, warp se
15、verely 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 stresses,When doubt exists as to whether internal stresses will cause warpage, a piece can be checked by heating it to about 1100 and then letting it cool. 当是否内应力会引起翘曲的怀疑存在时，可以通过将工件加工至1100 然后进行冷却来验证。,16,Internal s
16、tresses,If there are internal stresses, the piece is likely to deform. Pieces that will warp severely while being heated have been seen, yet the heat-treater was expected to put them through and bring them out better than they were in the first place. 如果存在内应力，工件会发生变形。经过热处理的工件像我们看到的那样会发生严重的翘曲，但是我们仍然希望工件被扔到热处理炉中被处理，这样好过它存在内应力的状态。,17,Welding,
