钢铁经过加热、保温和不同的速度冷却就可以改变内部的组织结构而显著提高和改善性能,这样的操作工艺就称为热处理。现代工业生产上已经采用了五十多种不同原理的热处理方法,但是主要的热处理方法还不外是工人师傅所常说的四把火(退火、正火、淬火和回 Steel through heating, insulation and cooling at different speeds can change the internal organizational structure and significantly improve and improve performance, this operation is called heat treatment process. Modern industrial production has adopted more than fifty different principles of heat treatment, but the main method of heat treatment is no more than four fires often called by workers’ masters (annealing, normalizing, quenching and returning