1200MPa级热轧超高强钢组织及性能

Research on microstructure and mechanical properties of 1200 MPa grade hot rolled ultra-high strength steel

针对超高强钢的开发,介绍了马钢1200 MPa级超高强的化学成分设计及生产工艺。利用金相显微镜、扫描电镜、透射电镜、电子拉伸试验机、布氏硬度计以及湿式橡胶轮试验机等,研究了免热处理1200 MPa级热轧超高强钢的组织及力学性能、冷弯性能、表面布氏硬度和耐磨性能。结果表明,1200 MPa级热轧超高强钢的显微组织为马氏体+铁素体,马氏体体积分数为70%~75%,铁素体体积分数为25%~30%;其R_(p0.2)≥800 MPa,R_(m)≥1200 MPa,R_(p0.2)/R_(m)≤0.70,A_(50)≥15%,表面布氏硬度不小于350HBW;90°冷弯,D=2a合格,具有高强度、高硬度、易成形的特点;同时,1200 MPa热轧高强钢的耐磨性优异,其耐磨性分别是500、800 MPa级高强钢的2.05~2.1倍、1.38~1.39倍。

To development of ultra-high strength steel,the chemical composition design and production process of 1200 MPa ultra-high strength steel in Masteel were introduced.Microstructure,mechanical properties,cold bending performance,Brinell hardness and abrasive wear behavior of 1200 MPa grade hot rolled ultra-high strength steel,which produced without heat treatment,were studied by means of OM,SEM,TEM,electronic tensile tester,Brinell hardness tester and wet rubber rimmed wheel tester.The results show that microstructure of 1200 MPa grade hot rolled ultra-high strength steel is martensite and ferrite,with the volume fraction of martensite and ferrite is 65%-75%and 25%-35%respectively.It has high strength,high hardness,well cold bending performance,and its typical mechanical properties are R_(p0.2)≥800 MPa,R_(m)≥1200 MPa,R_(p0.2)/R_(m)≤0.70,A_(50)≥15%,Brinell hardness is not less than 350HBW,and under the condition of 90°、D=2a,the cold bending performance is qualified.Meanwhile,its wear resistance is 2.05-2.1 times and 1.3-1.39 times of 500 MPa and 800 MPa grade high-strength steel.