表面选区强化对钢轨波磨处轮轨滚动接触行为的影响

层流等离子体表面强化技术可大幅提高钢轨表面的硬度和耐磨性。为了揭示强化处理对轮轨滚动接触行为的影响,建立同时考虑钢轨表面选区强化和短波波磨的三维轮轨瞬态滚动接触有限元模型,数值计算了车轮高速滚过一个波磨周期的轮轨力、接触斑黏滑分布和残余应力应变。对比发现:表面选区强化对轮轨力和接触斑黏滑分布的影响较小,不影响钢轨承载性能;对钢轨表面残余应力应变分布的影响明显,残余应力主要集中在屈服强度较高的强化斑内而残余应变主要集中在韧性较好的基体材料上,表面选区强化有效结合了强化斑和基体材料的力学性能,形成了一种强韧的良好匹配。结果可为现场生产服务提供一定的理论指导和应用参考。

A Study on Influence of Surface Strengthening on Wheel-rail Rolling Contact Behavior at Rail Corrugation

Laminar plasma surface strengthening technology can greatly improve the hardness and wear resistance of the rail surface.In order to reveal the influence of strengthening treatment on wheel-rail rolling contact behavior,a three-dimensional finite element model of wheel-rail transient rolling contact was established,which took into account both selective rail surface strengthening and short-wave corrugation.The wheel-rail contact force,adhesion-slip distribution of contact patch and residual stress/strain were calculated numerically when the wheel rolled through a wavelength of corrugation.The results show that the surface strengthening has minor influence on the wheel-rail contact force and adhesion-slip distribution,which presents no effect on the bearing capacity of the rail.On the contrary,it poses greater influence on the distribution of residual stress and strain of rail surface.The residual stress mainly concentrates in the strengthened spot with higher yield strength,while the residual strain mainly occurs in the matrix material with better ductility,which effectively combines the mechanical properties of strengthening material and matrix material and forms a good match of strength and ductility.The results can provide some theoretical guidance and application reference for field production service.