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借助OM、SEM、热膨胀仪以及力学性能试验,对比研究了两种含W、Mo的新型热作模具钢(HDLM钢和HDCM钢)在回火过程中组织与性能转变。结果表明:两种试验钢的马氏体相变临界冷速分别为8℃/s和9℃/s,1080℃真空油淬后两种钢的组织为板条状上贝氏体。经回火后,二者均具有非常明显的二次硬化效应,硬化峰值均出现在580℃,在此状态下合金碳化物的早期弥散析出极大地提升了两者的硬度。冲击性能试验结果表明:两种试验钢的韧性变化趋势存在明显差异,HDLM钢的冲击性能远远低于HDCM钢,这主要是由于VC沿晶偏聚粗化使HDLM钢的内应力集中。
By means of OM, SEM, thermal dilatometer and mechanical properties tests, the microstructures and properties of two new hot work tool steels (HDLM and HDCM) containing W, Mo were comparatively studied during tempering. The results show that the critical cooling rates of martensitic transformation of the two kinds of test steels are 8 ℃ / s and 9 ℃ / s, respectively. The microstructure of the two steels is lath - like bainite after oil quenching at 1080 ℃. After tempering, both have a very significant secondary hardening effect, the peak value of hardening appears at 580 ℃. In this state, the early dispersion of alloy carbides greatly enhance the hardness of both. Impact test results show that there is a significant difference in the toughness between the two test steels. The impact performance of HDLM steels is much lower than that of HDCM steels.