Improvement of wear resistance in ferrite-pearlite railway wheel steel via ferrite strengthening and cementite spheroidization

It is important and necessary to improve the wear resistance of ER8 railway wheel steel without changing its hardness. In this paper, ferrite strengthening and cementite spheroidization were adopted to achieve the better wear performance in the improved wheel steel, i.e., HiSi steel. Firstly, alloying elements including Si, Mn and Ni were added to achieve ferrite strengthening. Besides, high-temperature tempering was applied to the HiSi steel to break the lamellar cementite into plates and spheroids. Subsequently, ER8 and HiSi steels were subjected to sliding wear test against to U71MnG steel. Finally, wear performance and relevant mechanisms were discussed in detail. Compared to the ER8 steel with lamellar cementite, the HiSi steel showed lower UTS of 846 MPa but higher elongation of 23.12% and Charpy absorbed energy of 37 J due to the spherical cementite. Moreover, less wear losses of the single pin and tribological pairs were also achieved in the HiSi steel. Adhesive wear and surface cracking were the dominant wear damage for both wheel pins. HiSi pin displayed more adhesive film, less and shallower surface cracks, thicker deformation layer and would suffer lower shear stress and normal stress. The better wear resistance of the HiSi steel can be attributed to the ferrite strengthening, less proeutectoid ferrite and granulate pearlite simultaneously.