Switches and crossings (S&Cs) in rail networks suffer from damage and deformation due to severe loading of their complex geometric shapes. This article presents a comparative study of the cyclic deformation characteristics and fatigue behavior of two typical crossing materials, namely head-hardened pearlitic steel and Hadfield manganese steel, as well as the associated microstructural changes. Both uniaxial and biaxial loadings (proportional and non-proportional) are studied. The pearlitic steel endured more cycles to failure for a given strain amplitude compared to the manganese steel. The cyclic response of manganese steel shows significant hardening whereas softening was observed for the pearlitic steel except under biaxial non-proportional loading. The microstructures developed in the two types of steels after deformation are characterized by optical (OM) and transmission electron microscopy (TEM). TEM micrographs reveal that the deformed microstructure of the pearlitic steel consists of threading dislocations and dislocation tangles in the ferrite lamellae. The microstructures in the manganese steel after the different loadings are composed of dislocation cells with dislocation tangles inside, intersected by straight stacking fault lamellae. The observed microstructures are related to the results of the mechanical test, and the suitability of the steels for use in S&Cs is discussed.

铁路网络中的道岔和道口（S＆C）由于其复杂的几何形状的严重载荷而遭受损坏和变形。本文对两种典型的交叉材料（头硬化珠光体钢和Hadfield锰钢）的循环变形特性和疲劳行为以及相关的组织变化进行了比较研究。研究了单轴和双轴载荷（比例和非比例）。与锰钢相比，在给定的应变幅度下，珠光体钢经受了更多的破坏循环。锰钢的循环响应显示出明显的硬化，而珠光体钢则观察到软化，除了在双轴非比例载荷下。两种类型的钢在变形后形成的显微​​组织用光学（OM）和透射电子显微镜（TEM）表征。TEM显微照片显示，珠光体钢的变形显微组织由铁素体薄片中的螺纹位错和位错缠结组成。锰钢在不同载荷作用下的显微组织由位错单元组成，位错缠结在内部，并由直堆叠的断层薄片相交。观察到的微观结构与力学测试的结果有关，并讨论了钢在S＆C中的适用性。TEM显微照片显示，珠光体钢的变形显微组织由铁素体薄片中的螺纹位错和位错缠结组成。锰钢在不同载荷作用下的显微组织由位错单元组成，位错缠结在内部，并由直堆叠的断层薄片相交。观察到的微观结构与力学测试的结果有关，并讨论了钢在S＆C中的适用性。TEM显微照片显示，珠光体钢的变形显微组织由铁素体薄片中的螺纹位错和位错缠结组成。锰钢在不同载荷作用下的显微组织由位错单元组成，位错缠结在内部，并由直堆叠的断层薄片相交。观察到的微观结构与力学测试的结果有关，并讨论了钢在S＆C中的适用性。