外文翻譯---模具成型軋制-免費閱讀
【正文】 另外，在加工過程中由于冷作硬化，機(jī)械特性通常得以提高。于是沒有冷作硬化，因此無須昂貴耗時的中間退火。彎曲如其名所示，這是一道塑性彎曲一塊金屬薄板以獲得所需形狀的工藝。產(chǎn)品的形狀和尺寸由軋輥及其輪廓之間的間隙來決定。在熱加工過程中，可以產(chǎn)生大的塑性變形而無大的冷作硬化。 in such cases, hot working is less advantageous. Apart from this, strain hardening may be essential for a successful pletion of some processes (., in deep drawing, strain hardening prevents the rupture of the material around the bottom circumference where the stress is maximum). Large products and high strength materials can be worked upon under hot conditions since the elevated temperature lowers down the strength and, consequently, the work load. Moreover, for most materials, the ductility increases with temperature and, as a result, brittle can also be worked upon by the hot working operation. It should, however, be remembered that there are certain materials (viz., steels containing sulphur ) which bee more brittle at elevated temperatures. When a very accurate dimensional control is required, hot working is not advised because of shrinkage and loss of surface metal due to scaling. Moreover, surface finish is poor due to oxide formation and scaling. The major advantages of cold working are that it is economical, quicker, and easier to handle because here no extra arrangements for heating and handling are necessary. Further, the mechanical properties normally get improved during the process due to strain hardening. What is more, the control of grain flow directions adds to the st
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