激光淬火深度对钢轨疲劳磨损性能的影响研究

Effect of Laser Hardening Depth on Rolling Contact Fatigue Property of Steel Rail

目前全长热处理钢轨在使用过程中存在侧磨、压溃、剥离掉块等问题,为了进一步提高钢轨的使用寿命,在钢轨表面制备了4种不同深度激光的淬火层,利用滚动接触疲劳磨损试验机对疲劳磨损性能进行了测试,并对表面磨损形貌、断面显微组织以及磨损机理进行了分析。结果显示:原始钢轨试样的硬度只有35 HRC,磨损以塑性变形和疲劳剥落为主,表面产生严重的波磨。激光淬火后表面硬度提高到62 HRC以上,磨损机理只有表层轻微的疲劳剥落。0.7 mm淬火层试样磨损失重减少了50%,1 mm淬火层试样磨损失重减少了71.5%,随着淬火层深度增加,磨损失重减少。当淬火层深度低于0.7 mm时,淬火层边缘产生严重的接触疲劳裂纹,只有当淬火层深度达到1 mm时,才能完全消除宏观裂纹产生。钢轨表面的接触疲劳抗性随着淬火层深度增加而增加。

Nowadays,online slack quenched rail has been widely used,but some troubles still exist such as side attrition,collapse and spalling.In order to further improve the service life of rail,hardened layers with four different depths were prepared on rail surface by using laser hardening process.Wear and rolling contact fatigue property were investigated,and corresponding surface morphology,cross-sectional microstructure and wear mechanism were also analyzed.Results show that the hardness of original steel rail is about 35 HRC,fatigue spall and plastic deformation with severe surface corrugation are primary wear mechanisms;After laser hardening process,the hardness increases to 62 HRC,and slight fatigue wear is dominated;The weight loss decreases with the increasing of hardened layer depth,the weight loss decreases about 50%for 0.7 mm depth specimen,and decreases about 71.5%for 1 mm depth specimen;Severe cracks generate at the edge of contact zone when hardened layer depth less than 0.7 mm,and these cracks can only be eliminated when hardened layer depth larger than 1 mm depth;The rolling contact fatigue resistance of rail surface increases with the increasing of hardened layer depth.