Characterization of yield surface evolution due to large plastic shear strains in pearlitic rail steel

In order to analyze the material state in the rail surface layer during service, R260 rail steel has been subjected to large shear strains. The evolution of the yield surface at different amounts of predeformation, corresponding to different depths in the railhead, has been characterized. As expected, it is found that the size of the yield surface and the degree of anisotropy increase with the amount of predeformation. However, the major changes occur already after the first of six predeformation cycles, indicating that the yield surface is anisotropic several millimeters into the railhead