U75V钢轨钢波磨的形成过程及其组织演变

Corrugation Formation and Microstructure Evolution of Rail Steel U75V

用光镜和扫描电镜结合表层硬度测试,研究U75V钢轨钢滚动磨损试样表面波磨形成过程及其表面形貌和表层组织变化.结果表明,磨损表面形成一层剧烈塑性变形层,其中铁素体和渗碳体明显细化.在波磨初期,随着转数的增加,剧烈塑性变形层厚度增加,在波磨中期和波磨后期,其厚度基本保持不变.波谷处剧烈塑性变形层厚度大于波峰处.波磨中期,磨损量增加,波磨后期,摩擦系数急剧升高.波峰处以粘着磨损为主,波谷处以疲劳磨损为主.表层硬度随转数增加而增加,波磨后期,表层硬度呈波浪形分布,硬度峰值位于波磨波谷位置,硬度谷值位于波磨波峰位置.

By means of optical and scan electron microscopes and with surface layer microhardness testing,the corrugation formation,surface morphology and surface layer microstructure of rail steel U75V specimens are investigated that processed different cycle rolling contact wear.The result shows that a severe plastic deformation layer is formed beneath the worn surface where ferrite and cementite lamellae are broken into pieces.The severe plastic deformation layer thickness is increased with wear cycle increasing at the initial-term of corrugation,while it remains the same at the medium-term and the final-term of corrugations and its thickness of the trough is greater than that of the crest.The wear loss is increased at the medium-term of corrugation,while friction coefficient increases rapidly at the final-term of corrugation.Surface wear mechanism of the crest and trough is adhesive and fatigue wear respectively.The surface layer hardness is increased with the increase in wear cycles,and the hardness in longitudinal cross-section along circumferential direction distributes periodically with the hardness peak at the trough while that of valley at the crest.