关键词: 槽帮钢30MnSiCrMo, 淬火回火；微观组织；强韧性

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