控冷处理对中高碳Si-Mn无碳化物贝氏体钢的组织与性能的影响

Effect of Controlled Cooling Treatment on the Microstructure and Properties of Medium-high Carbon Si-Mn Steels

探索了控制冷却热处理工艺对中高碳Si Mn无碳化物贝氏体钢的组织和力学性能的影响。结果表明,中高碳Si Mn钢经控冷工艺处理后在很宽的工艺参数范围内能够获得无碳化物贝氏体组织;随着试样在油中冷却时间的延长,块状残留奥氏体量不断减少,残留奥氏体薄膜含量不断增加;材料的强度、塑性和韧性随着油冷时间的延长而不断增加。材料经油中冷却7s～8s后在空气炉中360℃保温3600s～5400s处理具有最好的强度、塑性和韧性。这主要归因于残留奥氏体薄膜良好的机械稳定性和热稳定性及在机械载荷作用下的TRIP效应。

An experiment was conducted through controlled cooling in oil and subsequently holding in air furnace to treat the medium-high carbon Si-Mn steels. Effect of the controlled cooling treatment on the microstructure and mechanical properties of the tested steel were investigated. The results show that this process in a wide range of parameters can obtain the carbide-free bainite. Prolonging the cooling time in oil, the quantity of blocky retained austenite decreases but that of the thin film increases, so the strength, ductility and toughness of the tested steel are enhanced. The optimum combination of the strength, ductility and toughness is obtained when the tested steel is cooled in oil for 7s-8s and held in air furnace at 360°C for 3600s-5400s. All this effects are attributed to the mechanical and thermal stability, the excellent strain hardening ability and the TRIP effect of the retained austenite thin film.