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利用高温激光共聚焦显微镜原位观察Nb对轴承钢GCr15试样在连续冷却过程中奥氏体向马氏体转变的影响。结果表明,在马氏体相变过程中,板条状浮凸优先沿奥氏体晶界以及马氏体板条处形成,并与已有马氏体板条呈60°、120°或平行分布,马氏体数量急速增多,转变速率由快到慢,后形成的马氏体板条长度比先形成的短。添加0.018%和0.040%Nb微合金能比GCr15的M_s点分别提高8.3℃和11.5℃。
The effects of Nb on austenite-martensite transformation of GCr15 bearing steel during continuous cooling were observed in situ using a laser confocal microscope. The results show that during the martensitic transformation, lath-like embossments are preferentially formed along the austenite grain boundaries and at the martensite laths and are parallel to the existing martensite laths by 60 °, 120 ° or parallel Distribution, the rapid increase in the number of martensite, the transition rate from fast to slow, after the formation of martensite lath length shorter than the first formation. The addition of 0.018% and 0.040% Nb microalloyed can raise the M_s points by 8.3 ℃ and 11.5 ℃ respectively than GCr15.