局部堆焊修复U75V钢轨的滚动接触磨损特性

Rolling Contact Wear Characteristics of U75V Rail Repaired by Local Surfacing

对未堆焊和局部堆焊U75V钢轨试样进行干态+湿态两阶段连续滚动接触磨损试验,对比分析了2种钢轨试样的滚动接触特性及磨损行为。结果表明:2种钢轨试样的黏着系数在干态磨损阶段都在0.60左右,进入湿态磨损阶段急剧下降至0.25左右;干态磨损阶段局部堆焊钢轨试样的黏着系数略高于未堆焊钢轨试样,湿态磨损阶段则相反。局部堆焊钢轨试样的堆焊层主要由马氏体组成,硬度最高,磨损表面损伤轻微,未发现明显裂纹与塑性变形;热影响区由铁素体、珠光体与马氏体等组织组成,硬度居中,磨损后表面粗糙度最大,塑性变形较大且出现较多大角度扩展的裂纹;无堆焊区主要由珠光体组成,硬度最小,磨损后表面平坦,塑性变形较明显,出现少量裂纹。

The dry and wet two-stage continuous rolling contact wear tests were carried out on U75V rail samples without surfacing and with local surfacing.The rolling contact characteristics and wear behavior of the two rail samples were compared and analyzed.The results show that the adhesion coefficients of the two rail samples were both about 0.60 in the dry wear stage,and decreased sharply to about 0.25 into the wet wear stage;the adhesion coefficient of the local surfacing rail sample in the dry wear stage was slightly higher than the un-surfacing rail sample,and the wet wear stage was the opposite.The surfacing layer of the local surfacing rail sample mainly consisted of martensite and had the highest hardness.The wear surface damage of surfacing layer was slight,and no obvious cracks and plastic deformation were found.The heat affected zone was composed of ferrite,pearlite and martensite and the hardness was in the middle.After wear,the surface roughness of the heat affected zone was the largest,the plastic deformation was large and there were many cracks with large expansion angles.The nonsurfacing zone was mainly composed of pearlite and the hardness was the lowest.After wear,the surface of the nonsurfacing zone was flat,and obvious plastic deformation and a small amount of cracks were found.