残余奥氏体稳定性对贝氏体车轮钢高温力学性能的影响

Effect of Retained Austenite Stability on High Temperature Mechanical Properties of Bainitic Railway Wheel Steels

为探究无碳化物贝氏体车轮钢在高温环境下服役的力学性能与残余奥氏体稳定性的关系,对试样在室温到500℃进行静拉伸试验测试,使用扫描电镜、透射电镜、X射线衍射分析仪和电子背散射衍射等对室温到500℃拉伸后的试样进行表征。结果表明,无碳化物贝氏体车轮钢的组织为贝氏体铁素体和残余奥氏体。试样的抗拉强度随变形温度的升高呈先升高后降低的趋势,在300℃拉伸下无碳化物贝氏体钢具有最佳的塑性和强度匹配,抗拉强度可达1305 MPa,总伸长率为25.1%。残余奥氏体在300℃高温和应力作用下持续发生转变,使材料在高应变下保持高的加工硬化率,提高了车轮钢的强度和伸长率。

To explore the relationship between mechanical properties and the stability of retained austenite of free-carbide bainitic steel wheel service under the environment of high temperature,the static tensile test of the sample at room temperature to 500℃ was tested.The sample from room temperature to 500℃ were characterized by SEM,TEM,X-ray diffraction analyzer and electron backscattering.The results show that the microstructure of carbide-free bainitic wheel steels consists of bainitic ferrite and residual austenite.The tensile strength of the samples increases first and then decreases with the increase of deformation temperature.At 300℃,the carbide free bainite steel has the best plasticity and strength match,the tensile strength can reach 1305 MPa,and the total elongation is 25.1%.The continuous transformation of residual austenite under high temperature and stress at 300℃ makes the material maintain a high work hardening rate under high strain,which can significantly improve the strength and elongation of wheel steel.