淬火工艺及Nb元素对30MnB5钢原奥氏体晶粒度的影响

Effects of quenching process and Nb addition on prior austenite grain size of 30MnB5 steel

利用光学显微镜(OM),研究了淬火工艺及Nb元素对30MnB5钢的原奥氏体晶粒度的影响。结果表明:含Nb的30MnB5钢在淬火温度860~920℃,保温时间不超过60 min时,原奥氏体晶粒度具有良好的稳定性;当淬火温度达到950℃时,保温时间超过30 min后,原奥氏体晶粒尺寸随着保温时间增长逐渐变大;因此,淬火温度低于950℃时,Nb元素对30MnB5钢热处理过程中原奥氏体晶粒生长具有抑制作用;当淬火温度达到1000℃时,Nb元素仅在30 min以内对原奥氏体晶粒生长有轻微抑制作用,当淬火保温时间超过60 min时,Nb元素完全失去对原奥氏体晶粒生长的抑制作用。

Effects of quenching processes and Nb addition on prior austenite grain size of 30 MnB5 steel were studied by means of optical microscope(OM).The results show that the prior austenite grain size of 30 MnB5 steel containing Nb is stable when the quenching temperature is 860-920℃ and the holding time is less than 60 min.When the quenching temperature reaches 950℃ and the holding time exceeds 30 min,the grain size of the prior austenite gradually increases with the holding time increasing.Thus,when the quenching temperature is lower than 950℃,Nb has an inhibitory effect on the growth of the prior austenite grains in the heat treatment process of30 MnB5 steel.When the quenching temperature reaches 1000℃,Nb only has a slight inhibitory effect on the growth of the prior austenite grain within 30 min.When the quenching holding time exceeds 60 min,Nb completely loses its inhibitory effect on the growth of the original austenite grain.