热处理对复合铸造高铬高碳钢/碳钢耐磨材料微观组织及力学性能的影响

采用液-固复合的方法制备铸态复合耐磨试验钢,且分别进行等温淬火和淬火-回火处理,利用扫描电镜、硬度计及冲击性能测试研究了不同的热处理对高铬高碳钢/碳钢复合铸造耐磨钢组织和性能的影响。利用JMatPro软件对试验钢不同温度下平衡相种类与含量进行了计算。结果表明,铸态高铬高碳钢/碳钢复合材料耐磨层的微观组织由网状碳化物和粒状珠光体组成;基体层为由粗大的奥氏体在较快冷速下形成的魏氏组织。等温淬火后试验钢耐磨层形成了网状碳化物+细粒状碳化物+奥氏体+铁素体的微观组织,基体层形成了块状铁素体与珠光体的微观组织;淬火-回火后试验钢耐磨层形成了网状碳化物+细粒状碳化物+马氏体的微观组织,基体层形成马氏体+上贝氏体的微观组织。经过等温淬火的试验钢耐磨层硬度为493 HBW,冲击吸收能量为2.6 J,基体层冲击吸收能量为79.2 J;经过淬火-回火的耐磨层硬度为629 HBW,冲击吸收能量为1.6 J,基体层的冲击吸收能量为20.0 J。考虑复合耐磨钢需要抵抗较高冲击载荷,880 ℃保温2 h空冷至320 ℃保温5.5 h的等温淬火为更优的热处理工艺。

Effect of heat treatment on microstructure and mechanical properties of composite cast high chromium high carbon steel/carbon steel wear-resistant materials

High chromium high carbon steel/carbon steel composite wear-resistant steel was prepared by using liquid-solid composite method, and the effect of different heat treatments on microstructure and properties of the composite wear-resistant steel treated by austempering and quenching-tempering was studied by means of scanning electron microscope, hardness tester and impact property test, respectively. The types and contents of the equilibrium phases in the tested steel were calculated by using JMatPro software. The results show that the microstructure of the as-cast high chromium high carbon steel/carbon steel composite wear-resistant layer is composed of network carbide and granular pearlite. The substrate layer is a widmanstatten structure formed by coarse austenite at a faster cooling rate. After austempering, the microstructure of the wear-resistant layer of the tested steel is network carbide+fine-grained carbide+austenite+ferrite, and the substrate layer consists of massive ferrite and pearlite. After quenching and tempering, the microstructure of the wear-resistant layer of the tested steel is network carbide+fine-grained carbide+martensite, and the substrate layer is martensite+upper bainite. The hardness of the wear-resistant layer after austempering is 493 HBW, the impact absorbed energy is 2.6 J, and the impact absorbed energy of the substrate layer is 79.2 J. After quenching and tempering, the hardness of the wear-resistant layer is 629 HBW, the impact absorbed energy is 1.6 J, and the impact absorbed energy of the substrate layer is 20.0 J. Considering that the composite wear-resistant steel needs to resist high impact load, the better heat treatment process is austempering: heating at 880 ℃ for 2 h then cooling to 320 ℃ and at which holding for 5.5 h.