Abstract：In order to develop gear steel for carburizing at high temperature of 980 ℃，austenite grain coarsening of case hardening steel 18Cr2Ni2Mo 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 18Cr2Ni2Mo 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 ℃.
张国强， 何肖飞， 尉文超， 时 捷， 王毛球. 高温渗碳齿轮钢的晶粒粗化行为[J]. 钢铁, 2019, 54(5): 68-72，77.
ZHANG Guo-qiang， HE Xiao-fei， YU Wen-chao， SHI Jie， WANG Mao-qiu. Grain coarsening behavior of high temperature carburizing gear steels. Iron and Steel, 2019, 54(5): 68-72，77.
2019, Vol. 54 
