金属热处理 Metal heat treatment

金属热处理 Metal heat treatment(中文3100字,英文2000字)
Metal heat treatment is a kind of craft to heat pieces of metals at the suitable temperature in some medium and to cool them at different speed after some time.
金属热处理是将金属工件放在一定的介质中加热到适宜的温度，并在此温度中保持一定时间后，又以不同速度冷却的一种工艺。
The metal heat treatment is one of the important crafts in the machine-building, comparing with other technologies, the heat treatment seldom changes the form of the work pieces and chemical composition of the whole .it improve the serviceability of the work piece through changing their micro- work pieces, chemical composition, or surface. Its characteristic is improving inherent quality of work pieces which can not be watched by our eyes.
金属热处理是机械制造中的重要工艺之一，与其他加工工艺相比，热处理一般不改变工件的形状和整体的化学成分，而是通过改变工件内部的显微组织，或改变工件表面的化学成分，赋予或改善工件的使用性能。其特点是改善工件的内在质量，而这一般不是肉眼所能看到的。