Study of Sliding Wear in Rail and Wheel Steels: Effect of Hardness Ratio and Normal Load in Pin on Disc Test

Rails and wheels are one of the most expensive assets in the railways, and their life needs to be increased by existing methods such as using the optimum rail/wheel hardness ratio. This study aims to verify the synergistic effect of hardness ratio and normal load on the sliding wear resistance. For this, it was used as model system the test pin against disc. The pins were extracted from a class C steel cast wheel (AAR Standard) and the discs were extracted from premium and intermediate grade steel rails (AREMA Standard). Rails are pearlitic and the bainitic wheel is in its first life. Both are hypereutectoid steels with hardness between 321 and 392 HB. The results of the unlubricated sliding tests made possible to compare the sliding wear resistance as a function of the three normal loads (40, 80 and 120 N). The sliding wear behavior for some of the singly body wear rate cases here studied served to validate the field and laboratory tests presented in the literature. From a crossing between the results of the literature and the present study, it is recommended aiming reduction of the wear of rail and/or wheel in a unlubricated condition, to adopt the optimal hardness ratio between rail/wheel R_Optimal ≥ 1.0, proposed in the field study (Steele and Reiff 1982), and/or 1.0 ≤ R_Optimal ≤ 1.1 proposed by the laboratory test and mathematical model (Razhkovskiy et al. 2015).