淬火方式对M42高速钢组织和性能的影响

Effects of quenching methods on microstructure and properties of M42 high speed steel

采用不同淬火方式（沙冷，雾冷，油冷，水冷）处理M42高速钢，通过SEM、AFM、XRD及维氏硬度仪研究不同冷却速率（1～35℃/s）对该合金微观组织与硬度的影响。结果表明，随淬火冷却速率增大：冷却过程中碳化物析出减少，淬火态残余奥氏体量增加；回火马氏体尺寸从150～200 nm减少到30～60 nm，马氏体晶界上二次碳化物析出量增多且尺寸减小；淬火态合金硬度从835 HV降低至788 HV，回火时二次硬化效果更加明显，回火态合金硬度从945 HV升高至1002 HV，红硬性硬度从856 HV升高至924 HV。

M42 high speed steel was quenched by medium of sand, fog, oil and water. By means of SEM、AFM、XRD and Vickers hardness tester ,the effect of quenching rate on the microstructure and hardness of PM M42 high speed steel was studied. The results show that, with increasing the cooling rate, the content of carbide precipitation during the quenching process decreases, while the content of retained austenite increases. Dimension of tempered martensite reduces from 150～200 nm to 30～60 nm, and the quantum of secondary carbide precipitation on the grain boundary of martensite increases while the size decreases. Hardness of quenched alloy reduces from 835 HV to 788 HV, and the secondary hardening effect is more obvious during the tempering treatment, meanwhile, hardness of tempered alloy increases from 945 HV to 1 002 HV, red hardness increases from 856 HV to 924 HV.