温锻和等温正火对20CrMnTiH3齿轮钢渗碳淬火后奥氏体晶粒度的影响

通过理化和原材料奥氏体晶粒度检验分析了温锻（880~930℃）加工工艺对20CrMnTiH3齿轮钢奥氏体晶粒长大的影响,得到温锻加工齿轮工序在后续890~920℃渗碳过程中该钢奥氏体容易异常长大,830℃渗碳淬火后转变为粗大马氏体组织。温锻后回火、普通正火工艺对渗碳淬火后20CrMnTiH3齿轮钢奥氏体晶粒粗大无改善效果,而通过950℃1 h空冷至650℃8h空冷的等温正火工艺可以避免渗碳淬火后粗大马氏体。

Effect of Warm-Forging and Isothermal Normalizing on Austenite Grain Size of Carburized and Quenched Gear Steel 20CrMnTiH3

The effect of process of warm-forging at 880 ~ 930 °C on growth of austenite grain of gear steel 20CrMnTiH3 is analyzed by examination of physicochemistry and original material austenite grain size to get that the austenite of steel is easy abnormally coarsening during carburizing process at 890 ~ 920 °C after warm-forging gear processing, that transforms to coarse martensite structure after cemented-quenching at 830 °C. There is no obvious improvement for coarse austenite grain of carburized and quenched gear steel 20CrMnTiH3 by tempering and normal normalizing process after warm forging, but the occurrence of coarse martensite of carburized and quenched steel is avoided by isothermal normalizing process at 950 °C for 1 h air cooling to 650 °C for 8 h air cooling.