【作者】 何国球； 刘晓山； 杨洋；

【Author】 He Guoqiu;Liu Xiaoshan;Yang Yang;School of Materials Science and Engineering,Tongji university;

【机构】 同济大学材料科学与工程学院；

【摘要】 现代轨道交通关键材料的服役行为十分重要,高速铁路中存在许多复合微动失效的"紧"配合件,其中轮轴钢35CrMoA冷切断裂就是由于轮轴压装部位的微动疲劳引起,微动疲劳会缩短轮轴寿命,甚至带来列车脱轨等严重事故。本文以高速列车车轴钢35CrMoA为研究对象,在面/面接触条件下,研究了接触应力对材料在方形路径加载下的拉扭复合微动疲劳行为的影响,主要研究结论如下:在方形路径加载下,等效应力幅值为400MPa,接触应力分别为50MPa、150MPa、250MPa时,随着接触应力增大,摩擦功及内耗越大,轴向及扭向的应力-应变循环滞后环的面积变大,微动疲劳寿命非线性降低。在相同接触应力下,随着循环周次的增加,轴向应力-应变滞后环面积变大。微动疲劳裂纹源形成于磨损表层,同时裂纹萌生处发生了明显的氧化现象而使其颜色较暗,并附有褐色的氧化物磨屑,是微动疲劳裂纹最先形成的部位。微动磨损一方面加速微裂纹的萌生,另一方面推迟微裂纹扩展,在微动磨损过程中这两方面的作用都是同时存在的。当等效应力幅值相同而接触应力值较低时,滑移区较宽,粘着区则相对较窄,试样断裂失效的主裂纹越靠近微动斑的中央。当等效应力幅值相同而接触应力较小时,微动疲劳裂纹源相对较多,除主裂纹之外,还有许多次微裂纹在微动表面生成。更多还原

【Abstract】 Nowadays it is very important for the behavior of the rail materials.There are many failure "fretting" mating parts in the high speed railway,such as the 35 CrMoA cold cutting due to the fretting fatigue.Fretting fatigue can shorten the life of the axle,even lead to serious accidents,such as the train derailment.In this paper,the effects of contact stress on the multiaxial fretting fatigue properties of 35 CrMoA axle steels was studied under the square loading paths and surface/surface contact conditions,the main conclusions are as follows:Under the square loading paths,at the same equivalent stress amplitude(400MPa) and the different contact stress(50MPa,150 MPa,250MPa),When the contact stress is large,the fretting wear is more serious and the contact surfaces step into the process of steady state wear are faster.Therefore the cyclic softening rate is higher.The fretting fatigue initiation cracks are formed in the wear surface.Meanwhile,significant oxidation is occurred at the crack initiation.,the initiation of microcracks is effected by both of the cyclic fatigue stress and the fretting wear.The initiation of microcracks is effected by both of the cyclic fatigue stress and the fretting wear,he fretting wear accelerate the initiation of microcracks on one hand,and on the other hand it postpone the propagation of microcracks.They are exist simultaneously.When the contact stress is low,the slip region is wide,and the stick region is relatively narrow at the same equivalent stress amplitude.When the contact stress is low,the fretting fatigue crack initiation is relatively large at the same equivalent stress amplitude.Besides,there are many microcracks generated at the fretting surface.更多还原