钢轨打磨磨痕粗糙度与交叉磨痕对滚动接触疲劳损伤的影响

利用砂纸在钢轨试样表面打磨出不同粗糙度等级(1、4和7 μm)的单向磨痕和交叉磨痕(?45°/70°、?20°/90°和45°/70°)，利用MMS-2A轮轨摩擦磨损试验机对打磨后的钢轨试样进行滚动试验并分析滚动接触疲劳损伤规律. 结果表明:打磨钢轨的滚动磨损表面粗糙度和损伤均比未打磨钢轨严重，随打磨磨痕粗糙度增加，钢轨滚动磨损表面粗糙度和损伤均呈减小趋势. 当打磨粗糙度为7 μm时，滚动接触疲劳裂纹为枝裂纹，裂纹深度较小；随打磨粗糙度减小，枝裂纹发生贯穿连通形成网状裂纹损伤，裂纹深度增加. 相较于单向打磨钢轨，交叉打磨磨痕钢轨滚动磨损表面粗糙度较低，滚动接触疲劳损伤较轻微. 此外，?45°/70°和45°/70°交叉磨痕的滚动损伤比?20°/90°交叉磨痕钢轨更加轻微. 

Influences of Grinding Mark Roughness and Cross Marks on Rolling Contact Fatigue Damage of Rail

Grinding marks with different roughness levels (1, 4, 7 μm) and cross grinding marks were produced on the rail samples using abrasive papers. Then, rolling tests were conducted using those ground rail samples on the MMS-2A wheel/rail friction and wear machine. After that, the rolling contact fatigue of ground rail was analyzed. The results indicated that the roughness and damage of worn surfaces of ground rails were severer than those of unground rails. With the increase in the grinding roughness, the roughness and damage of worn rails showed a decrease trend. When the grinding roughness was 7 μm, branch cracks were generated, the depth of cracks was small. With the decrease in grinding roughness, branch cracks connected with each other, then net-like cracks were generated, the depth of cracks was increased. When the rails were ground with cross grinding marks, the roughness and rolling contact fatigue damage of worn rails were alleviated. The rolling damage of the ground rail with the ?45°/70° and 45°/70° cross marks was milder than that of ?20°/90° cross marks.