Abstract
Rail grinding and wheel turning can effectively remove surface defects and unevenness, which is a crucial process for the safe and smooth operation of trains. Machined surface integrity of wheel/rail materials significantly influences their tribological property. In this study, firstly, the rail blocks were ground via a cylindrical grinding machine, and the wheel rings were turned by a computer numerical control (CNC) lathe with varied parameters. Then, the sliding wear and damage characteristics of the machined wheel/rail samples under dry conditions were studied by virtue of a block-on-ring tribometer. The results show that the surface microhardness of the ground rail blocks is larger than that of wheel rings, while the surface roughness and the thickness of the subsurface plastic deformation layer (SPDL) of rail blocks are much smaller than those of wheel rings. After sliding, the surface microhardness of wheel/rail samples increases remarkably. The thickness of the SPDL, the wear loss, and the increase degree of surface microhardness of rail blocks are larger than those of wheel rings. Surface microhardness, roughness and the SPDL of the machined wheel/rail samples impose a combined influence on the anti-wear property, and the tribological pair with proper initial surface roughness and microhardness engenders the smallest amount of total wear loss.
Highlights
subsurface plastic deformation layer (SPDL), the wear loss, and the increase degree of surface microhardness of rail blocks are larger than those of wheel rings
Aiming at eradicating the unfavorable diseases existing on the surfaces of wheel/rail materials, it has been increasingly vital to carry out regular wheel/rail maintenance practices to restore their profiles, which can guarantee the proper and secure wheel/rail contact
We conducted a systematic investigation on the rolling-sliding wear behaviors of machined wheel/rail materials, and we found that the rail material displays better anti-wear properties and that a thicker SPDL
Summary
SPDL, the wear loss, and the increase degree of surface microhardness of rail blocks are larger than those of wheel rings. The ever-increasing train speed and traffic volume bring a series of challenges to the railway industry due to the fact that the flaws generated by the dynamic and intricate wheel/rail interaction are more likely to happen under harsher and more complex service conditions, such as surface spalling [1], fatigue cracks [2], head checks [3] and squats [4], etc. Aiming at eradicating the unfavorable diseases existing on the surfaces of wheel/rail materials, it has been increasingly vital to carry out regular wheel/rail maintenance practices (namely, rail grinding and wheel turning) to restore their profiles, which can guarantee the proper and secure wheel/rail contact. Wang et al [12] investigated the impact of creepage in the propagation of rolling contact fatigue (RCF)-related cracks of rail material under wet conditions, and they concluded that the worn surface morphology of the studied material shifts from slight surface fatigue crack to serious fatigue crack and pitting as the creepage changes from 0 to 10%
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