含钛中锰钢淬火-配分组织及力学性能

Quenching and partitioning microstructure and mechanical properties of medium manganese steel bearing titanium

为了研究淬火-配分含钛中锰钢的组织与力学性能,借助扫描电子显微镜,透射电子显微镜、电子背散射衍射技术与万能拉伸试验机、磨粒磨损试验机等,分析与测试了含钛中锰钢在165~240℃淬火380℃配分处理后组织、强度、塑性与磨粒磨损性能。结果表明,试验钢淬火-配分组织主要为板条状一次马氏体、块状二次马氏体及残余奥氏体,同时含有大量微米级TiN和纳米级(Ti,Mo)C及TiN-(Ti,Mo)C复合析出相。190℃淬火380℃配分后残余奥氏体体积分数最高为12.5%。试验钢不同温度淬火与配分后屈服强度均大于1000 MPa,抗拉强度均大于1500 MPa,硬度从482.5HV增大到542.2HV,伸长率范围为9.2%~14.5%,在165~190℃淬火-配分处理后其抗磨粒磨损性能优于220~240℃淬火-配分钢。磨损机制主要是塑性变形和疲劳破坏,磨损过程中残余奥氏体发生应变诱导马氏体相变(TRIP)效应,析出相颗粒阻断基体塑性变形过程犁沟的前进和刮削行为,含钛中锰钢通过淬火-配分引入一定体积分数的残余奥氏体,有利于提高钢的强塑性与抗磨损性能。结合力学性能指标,含钛中锰钢最佳淬火-配分工艺为900℃奥氏体化30 min,190℃淬火,380℃配分10 min。

In order to research the microstructure and mechanical properties of medium manganese steel bearing titanium,the microstructure and strength and ductility and abrasive wear properties of the medium manganese steels after quenching from 165℃ to 240℃ and partitioning at 380℃ for 10 min were studied by scanning electron microscope,transmission electron microscope and electron backscatter diffraction technique and Universal tensile testing machine and abrasive wear tester.The results show that the microstructure of the test steel are mainly composed of lath primary martensite,block secondary martensite,retained austenite,large number of micro-scale TiN and nano-scale precipitated phase particles(Ti,Mo)C and TiN-(Ti,Mo)C composite phase in the test steel.The highest volume fraction of retained austenite is 12.5%for the steel quenched at 190℃ and partitioning at 380℃ which yield strength is more than 1000 MPa,the tensile strength is more than 1500 MPa,and the hardness is from 482.5HV to 542.2HV,the elongation is from 9.2%to 14.5%.The wear resistance of the test steel after quenching from 165℃ to 190℃ is better than that of the steels quenching from 220℃ to 240℃ .Wear mechanism is mainly micro-cutting and fatigue failure.Strain induced martensitic transformation(TRIP)effect occurs in residual austenite during wear,and precipitated phase particles hinder the plow during plastic deformation and scraping behavior of abrasive particles.The experiments indicates that a certain volume fraction of retained austenite in the steels by quenching-partitioning treatment is beneficial to improve the properties of strength and ductility and wear resistance.The optimized quenching partitioning process of the steel with optimal mechanical properties is austenitizing 30 min at 900℃ following quenching at 190℃ and then partitioning at 380℃ for 10 min.