We describe here the high cycle fatigue (HCF) behavior of a rail steel comprised of multiphase structure of bainite, martensite and film-like retained austenite, which was processed by the quenching and tempering (Q&T) heat treatment process. Conventional mechanical properties of experimental materials were determined, and the high cycle fatigue S–N curve of rail steel was obtained through ultrasonic fatigue test. The fatigue fracture details under cyclic stress were observed and analyzed in detail by scanning electron microscope (SEM). It was observed that the bainite/martensite (B/M) composite structure exhibited good performance, and its fatigue limit was as high as ~790 MPa, meanwhile the ratio of the fatigue limit to the tensile strength of rail steel was up to ~0.53. Finally, a comparison of the mechanical properties with other high-strength steels was made, which suggested that the rail steel with multiphase structure has both good strength and high fatigue limit. Thus, multiphase structure of steel has broad prospects in engineering applications.

我们在此描述了由贝氏体、马氏体和膜状残余奥氏体的多相结构组成的轨道钢的高周疲劳 (HCF) 行为，该钢通过淬火和回火 (Q&T) 热处理工艺处理。确定了实验材料的常规力学性能，并确定了高周疲劳S-N通过超声疲劳试验得到钢轨钢的曲线。通过扫描电子显微镜（SEM）对循环应力作用下的疲劳断裂细节进行了详细的观察和分析。观察到贝氏体/马氏体（B/M）复合结构表现出良好的性能，其疲劳极限高达~790 MPa，同时轨道钢的疲劳极限与抗拉强度之比高达~0.53 . 最后，与其他高强度钢进行了力学性能对比，表明多相结构钢轨钢具有良好的强度和较高的疲劳极限。因此，钢的多相组织在工程应用中具有广阔的前景。