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采用OM、XRD、SEM和EDS以及硬度测试等方法对精密喷射成形HM1热作模具钢的微观组织、物相、元素分布及硬度等进行了分析,并与铸态材料进行了比较。结果表明,铸态组织为粗大的枝状晶,晶粒尺寸150～200μm,晶界处为粗大连续的网状碳化物组织;喷射态HM1钢为细小的等轴晶组织,晶粒尺寸20～50μm,晶界处弥散分布少量细小的先共析碳化物相,喷射态材料有效的消除了元素偏析和网状碳化物组织。对喷射态和铸态材料进行回火处理的研究表明,喷射态材料回火后具有比铸态材料回火后更高的硬度,其高温耐热性提高;在520℃回火2 h,喷射态硬度达52～54 HRC,铸态为50～51 HRC。
The microstructure, phase, elemental distribution and hardness of precision injection-molded HM1 hot work die steel were analyzed by OM, XRD, SEM and EDS as well as hardness test. The results were compared with that of as-cast material. The results show that the as-cast microstructure is coarse dendrite with the grain size of 150 ~ 200μm and coarse and continuous network carbides at the grain boundaries. The as-sprayed HM1 steel is a fine equiaxed grain with the grain size of 20 ~ A small amount of fine pro-eutectoid carbide phase was dispersed in the grain boundary at 50μm. The sprayed-state material effectively eliminated elemental segregation and reticular carbide structure. The research on the tempering of the as-cast and as-cast materials shows that the as-sprayed material has a higher hardness after tempering than that of the as-cast material, and its high temperature heat resistance is improved. After tempering at 520 ℃ for 2 h, State hardness of 52 ~ 54 HRC, cast as 50 ~ 51 HRC.