Experimental study on wear properties of wheel and rail materials with different hardness values

This paper aimed to investigate the wear properties of different wheel-rail material pairs with various hardness values. Twin-disc wear experiments were carried out via cross-matching five types of wheel material (ER7, ER8, CL60, C-class and D-class) and four types of rail material (U71Mn, U75V, PG4 and PG5). The effects of bulk hardness, post-test hardness, hardening ratio, and rail/wheel hardness ratio (HR/HW) on the wear rate of wheel and rail materials were analyzed. The results indicated that the wheel wear rates decreased with wheel bulk hardness and slightly increased with the rail bulk hardness. However, the rail wear rates decreased with the increasing wheel bulk hardness under 1% creepage and 1500 MPa contact pressure. In addition, both the wheel and rail wear rates showed increasing trends with the increase in wheel hardening ratio and the pre-test HR/HW. The surface damage of the harder Cclass and D-class wheels, and the high-hardness PG4 and PG5 rail materials were relatively slight. The premium PG4 and PG5 rails possessed significantly shorter cracks than the base material pair (ER8-U71Mn), whereas, the fatigue cracks in U75V rail steel were relatively longer. The results will not only help optimize wheel and rail hardness matching, but also improve the prediction of wear and crack growth reliant on wheel and rail material properties.