高温渗碳齿轮钢的晶粒粗化行为

Grain coarsening behavior of high temperature carburizing gear steels

为了开发适合980℃高温渗碳的齿轮钢,利用伪渗碳方法,研究了铌质量分数为0、0.036%、0.060%和0.100%的18Cr2Ni2Mo渗碳齿轮钢在930和980℃的晶粒粗化行为。结果表明,由于析出NbC钉扎晶界,铌微合金化可以显著细化试验钢在930和980℃奥氏体化后的晶粒尺寸,且随着铌质量分数增加,铌微合金化明显抑制试验钢在980℃长时间奥氏体化晶粒粗化倾向。添加0.100%Nb的18Cr2Ni2Mo齿轮钢在980℃奥氏体化20 h后,平均晶粒尺寸仍然在26μm左右,适合于980℃高温长时间渗碳。

In order to develop gear steel for carburizing at high temperature of 980 ℃,austenite grain coarsening of case hardening steel 18 Cr2 Ni2 Mo with the addition of niobium in contents of 0,0.036%,0.060% and 0.100% was investigated by means of pseudo-carburizing at 930 and 980 ℃. Results show that the grain size of tested steel austenitizing at 930 and 980 ℃ can be significantly refined by niobium addition due to the pinning effect of NbC precipitates,and with the increase of niobium mass percent in steel,grain coarsening at high temperature of 980 ℃ can be evidently hindered. After austenitizing at 980 ℃ for 20 h,the average grain size of the 18 Cr2 Ni2 Mo gear steel with 0.100% Nb addition is still about 26 μm,so the steel can be used for carburizing at high temperature of 980 ℃.