Abstract: The microstructure evolution, and mechanical properties of new-type slot edge steel 30MnSiCrMo quenched at 900-920 ℃ for 30 min and tempered at 350-550 ℃ for2 h are studied by using optical microscope, scanning electron micro- scope, tensile, impact and Brinell hardness tester. The results show that martensite decomposition, transformation-aggregation-growth of carbide, and recovery-recrystallization of α phase happen during 350-550 ℃ different tempering process, the room temperature microstructure transits from tempered martensite to tempered troostite and tempered sorbite. With the in- crease of tempering temperature, the solid solution strengthening and carbide precipitation strengthening gradually weaken, the strength and hardness of testing steel continuously decrease, while the plasticity and toughness gradually increase. The excellent strengthen and toughen matching of the testing steel is obtained i.e. with austenitizing at 900 and 920 ℃ for 30 min, water quenching and tempering at 450-520 ℃ for 2h,the tensile strength of steel is 1159- 1008 MPa, the yield strength is 1107-944 MPa, the elongation after fracture is 11.8%- 15.0%,the room temperature hardness is 336- 293HBW,and the V-shaped impact absorption energy is 45.5-67.5 J, which could meet the requirements of strength and toughness of the central trough ledge.

Key words: Slot Edge Steel 30MnSiCrMo, Quenching and Tempering, Microstructure, Strength and Toughness

摘要： 采用光学显微镜、扫描电镜、拉伸冲击试验机及布氏硬度计等研究了新型槽帮钢30MnSiCrMo经900～920℃30 min淬火，350～550℃2h回火的组织性能变化。结果表明，350～550℃不同回火过程中，试验钢出现马氏体分解、碳化物转变、聚集长大及α相回复再结晶等转变，室温组织由回火马氏体向回火屈氏体和回火索氏体过渡。随着回火温度的上升，基体固溶强化与碳化物析出强化减弱，试验钢的强度与硬度连续降低，而塑性与韧性不断提高，试验钢在900和920℃30 min水淬后450～520℃2 h回火时获得良好的强韧性匹配，即抗拉强度1159～1008 MPa,屈服强度1107～944 MPa,断后伸长率11.8%～15.0%,室温硬度336～293HBW, V型缺口冲击吸收功45.5～67.5 J,能够满足中部槽材料的强韧性要求。

关键词: 槽帮钢30MnSiCrMo, 淬火回火；微观组织；强韧性