一、前言 按照传统的热处理制度,中碳CrNiMoA和CrNi3MoVA钢大型锻件在调质处理淬火前都要经过正火处理,正火的作用主要是改善锻钢的不均匀组织,为淬火作组织上的准备,以防产生淬火裂纹。但是,生产实践中,对某些零件、毛坯调质前不进行正火。有时是原始退火态;有时为了降低硬度,以便机械加工,在正火后再经650℃左右长时间 I. Preface According to the traditional heat treatment system, medium carbon CrNiMoA and CrNi3MoVA steel forgings are quenched before quenching are normalized, the main role of normalizing is to improve the uneven forging steel for the quenching for the organization Prepare to prevent quench cracking. However, the production practice, for some parts, rough quenched before normalizing. Sometimes the original annealing state; sometimes in order to reduce the hardness, in order to mechanical processing, after normalizing at about 650 ℃ for a long time