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采用Thermo-calc软件对EX1模具钢和8418模具钢的相图进行模拟计算,根据相图辅助制定双重淬火工艺,并对EX1钢和8418钢进行热处理,利用光学显微镜及SEM对经过不同步骤热处理后的两种钢的组织及断口进行观察,并对两种钢的力学性能进行测试。结果表明,经过高温淬火处理后,两种钢的微观组织均为细小的板条状马氏体,回火处理后,转变为回火索氏体,经过二次淬火后,微观组织为粗大的板条状马氏体。经过热处理后的EX1模具钢硬度为433.2 HV50,略低于8418模具钢的472.0 HV50,但EX1模具钢的冲击性能和拉伸性能优于8418模具钢。
The phase diagrams of EX1 die steel and 8418 die steel were simulated by Thermo-calc software. According to the phase diagrams, the dual quenching technology was developed. EX1 steel and 8418 steel were heat-treated. After heat treatment through different steps by optical microscope and SEM The microstructure and fracture of the two kinds of steel were observed, and the mechanical properties of the two kinds of steel were tested. The results show that after quenching, the microstructure of the two steels are fine lath martensite. After tempering, the microstructure of the two steels is transformed into tempered sorbite. After secondary quenching, the microstructure is coarse Lamellar martensite. After heat treatment, the hardness of EX1 die steel is 433.2 HV50 which is slightly lower than 472.0 HV50 of 8418 die steel, but the impact and tensile properties of EX1 die steel are better than that of 8418 die steel.