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对贝氏体钢轨钢不同工艺回火后的组织和性能进行研究。结果表明,350℃回火4 h及以上,贝氏体钢轨屈服强度大于1000 MPa,抗拉强度大于1200 MPa,伸长率和断面收缩率分别大于15%和45%,室温冲击功大于150 J;在450～550℃回火时,出现明显的回火脆性。金相显微镜和透射电子显微镜观察表明,贝氏体轨钢以粒状贝氏体组织为主,残留奥氏体在板条间以M-A岛状形式分布。不同回火温度及3%拉伸变形后试验贝氏体轨钢残留奥氏体的测定结果表明,350℃回火时的残留奥氏体机械稳定性最好。贝氏体钢轨的强韧性随回火温度的变化与残留奥氏体的机械稳定性密切相关。
The microstructure and properties of bainitic rail steel after tempering were studied. The results show that the yield strength of bainitic rail is more than 1000 MPa, the tensile strength is more than 1200 MPa, the elongation and the reduction of area are more than 15% and 45% respectively at 350 ℃ for 4 h and above, and the room temperature impact energy is more than 150 J ; Tempering at 450 ~ 550 ℃, the obvious temper brittleness. Metallographic and transmission electron microscopy observations showed that the bainitic rail steel was dominated by granular bainite and retained austenite was distributed as M-A islands between the laths. The results of the residual austenite in bainite steel after different tempering temperatures and 3% tensile deformation show that the retained austenite at 350 ℃ has the best mechanical stability. The toughness of bainitic rail changes with the tempering temperature is closely related to the mechanical stability of retained austenite.