The influence of heat treatment and cold deformation on pearlitic steel characteristics

During service, rails and wheels undergo considerable plastic deformation near the surface. The mechanical resistance to the deformation is determined by the microstructure obtained after processing. Therefore, we aim to determine the influence of the microstructure on the mechanical properties simulating service conditions. To achieve this, we heat treated a hypoeutectoid steel to achieve diverse microstructures. Afterwards we conducted compression tests at room temperature and 1 s-1 and 0.01 s-1 of strain rates to investigate the influence of heat treatment on the mechanical response of the specimens. Moreover, we measured hardness and presented microhardness maps. We concluded that the microstructural characteristics, for instance, prior austenite grain size, block size, interlamellar spacing, and proeutectoid ferrite, Pα, directly impact the mechanical resistance of the material. For instance, the presence of ferrite results in softening and strain rate sensitivity. This work establishes fundamental knowledge for investigating the microstructural changes that occur during manufacturing and throughout service.