珠光体轨钢磨损及损伤过程中的组织演变行为

Behavior of microstructure evolution during wear and damage of pearlitic rail steel

通过环块对磨试验,研究不同试验力以及循环周次下75 kg/m珠光体重载热处理轨钢的摩擦磨损性能,并与添加RE、Nb和Ni元素的轨钢对比。同时结合扫描电镜、透射电镜和电子探针技术,分析了试样磨损后表面形貌、剖面损伤、塑性变形区的微观组织演变以及元素含量变化。结果表明,随着试验力增大,磨损量增大,磨损形式由氧化磨损向粘着磨损和疲劳磨损过渡,变形区白层的厚度增大。随着摩擦磨损循环周次的增加,变形区晶粒更加细小,塑性变形层厚度变大。但在较大的试验力下,白层中的裂纹扩展相交后导致材料发生破碎,磨损量增加。添加RE、Nb和Ni元素的轨钢相较于原始态轨钢的珠光体片层间距细化了21.8%,珠光体片层间距越小,形成的白层厚度越小且不易破碎,因此具有更好的耐磨性。

Friction and wear performance of 75 kg/m pearlitic heavy-duty heat-treated rail steel was investigated by means of the ring-block butt-abrasion test at different test forces and cycle times,and compared with that of rail steel with RE,Nb and Ni elements adding.At the same time,the surface morphology,profile damage,microstructure evolution in the plastic deformation zone and elemental content changes of the specimens after wear were analyzed by using a combination of scanning electron microscope,transmission electron microscope and electron microprobe techniques.The results show that with the increase of test force,the wear loss increases,the wear form transitions from oxidizing wear to adhesive wear and fatigue wear,and the thickness of the white layer in the deformation zone increases.With the increase of friction wear cycle times,the grain size of the deformation zone is finer,and the thickness of the plastic deformation layer becomes larger.However,under the larger test force,the crack extension in the white layer intersects and causes the material to break,and the wear loss increases.The pearlitic lamellar spacing of the rail steel with adding RE,Nb and Ni elements is refined by 21.8%compared with that of the original state rail steel,and the smaller the pearlite lamellar spacing is,the smaller the thickness of the white layer is formed and is less prone to breaking,and thus it has better wear resistance.