淬火与回火工艺对42CrMo钢显微组织和奥氏体晶粒长大规律的影响

研究了860～940℃淬火与200～600℃回火对42CrMo钢显微组织的影响，并用金相截线法对奥氏体晶粒尺寸进行测量，建立了42CrMo钢奥氏体晶粒生长动力学方程。结果表明，随着淬火温度和保温时间的增加，42CrMo钢中残留碳化物数量明显减少，碳化物由片状逐渐变为颗粒状。随着淬火温度的升高，板条马氏体组织变得越来越均匀细小。随着回火温度的升高，钢的显微组织向回火屈氏体、回火索氏体转变，当回火温度为600℃时，得到的回火索氏体组织更均匀密集。基于Beck模型的42CrMo钢奥氏体晶粒生长规律的拟合结果，得出奥氏体晶粒长大激活能为2.62×10³ J·mol^-1。

Effect of quenching and tempering process on microstructure and austenite grain growth of 42CrMo steel

Effect of 860-940 ℃ quenching and 200-600 ℃ tempering processes on microstructure of 42CrMo steel was studied, the austenite grain size of the steel was measured by using metallographic linear intercept method, and the austenite grain growth kinetic equation of the steel was established. The results show that with the increase of quenching temperature and holding time, the number of residual carbides in the 42CrMo steel decreases obviously, and the carbides gradually change from flake to granular. With the increase of quenching temperature, the lath martensite becomes more and more uniform and fine.With the increase of tempering temperature, the microstructure of the steel changes to tempered troostite and tempered sorbite. When the tempering temperature is 600 ℃, the tempered sorbite is more uniform and dense. The fitting results of austenite grain growth of the 42CrMo steel based on Beck model shows that the activation energy of austenite grain growth is 2.62×10³J·mol^-1。