Simulation and Experimental Investigation of the Mechanical Properties of Wheel-Rail Contact for Laser Additive Repaired Rails Using Nickel-Based Powders

To address the issues of unstable heat input and susceptibility to cracking in repair layers associated with existing severe rail damage repair techniques (e.g., welding repair), this study proposes a combined laser additive manufacturing and grinding process for rail repair. By pre-machining damaged areas into 90°, 45°, and arc-shaped cavities and employing laser additive repair with nickel-based superalloys GH4169, GH3625, and a mixed powder of 50 wt% GH4169 and 50 wt% GH3625, the mechanical properties of the repair layers under wheel-rail contact loads were comprehensively investigated. Based on elastoplastic finite element simulations, this study is the first to reveal the influence of different cavity geometries and powder combinations on the stress distribution, vertical deformation, and contact forces in repair layers under 30 t axle load conditions. The results demonstrate that the arc-shaped cavity combined with GH4169 powder significantly reduces the maximum von Mises stress in the repair layer and effectively suppresses stress concentration. The vertical force on the repair layer with this combination is more than 10% lower than that with other materials, making it the optimal cavity-powder combination in this study. Laser additive repair experiments using GH4169 powder and arc-shaped cavities were conducted, followed by wheel-rail rolling contact tests. After cumulative passage of 2.4×105 t axle load, no damage was observed in the repair layer, preliminarily validating the reliability of the finite element simulation results.