摘要
钢轨在循环载荷下诱发的棘轮行为是导致钢轨滚动接触疲劳(Rolling contact fatigue,RCF)的主要原因,特别是钢轨焊接接头的软化区对RCF具有更高的敏感性。通过采用单轴应力控制循环试验,研究了U71Mn钢轨焊接接头中心区域(熔合线+热影响硬度区+熔合线)、热影响软化区和母材的棘轮行为演化规律。结果表明:U71Mn钢轨闪光焊焊接接头中心区域、软化区在非对称应力循环载荷作用下,表现出明显的棘轮行为,平均应力和应力幅值的增大会引起棘轮应变的增大,应力幅值对棘轮应变的影响大于平均应力的影响。硬度最低的软化区棘轮阻力最小,软化区上的球化组织减小了软化区的强度,增大了棘轮的敏感性,因而减小了软化区的寿命。中心区域的棘轮抵抗力最大,但是由于非金属夹杂物的存在,使它的寿命最短。三个区域的材料疲劳寿命与棘轮应变的关系不统一,其疲劳寿命分别与各自稳定棘轮应变率成对数关系,寿命随棘轮应变的增大而减小。研究结果可为钢轨焊接接头的本构模型提供材料参数。
The ratcheting behavior induced by cyclic load is the main cause of rail rolling contact fatigue(RCF),especially the softened zone of rail welded joint is more sensitive to RCF.The uniaxial stress control cycle tests were performed to investigate the ratcheting behaviour of the central zone(the bond line+the highest hardness zone)and the softened zone in a flash butt welds joint and the base metal.The results show that the central zone and the softened zone exhibit obvious ratcheting behavior under the cyclic load of asymmetric stress.The increase of average stress and stress amplitude will lead to the increase of ratcheting strain,and the influence of stress amplitude on ratcheting strain is greater than that of average stress.The softened zone with the lowest hardness has the lowest ratchet resistance.The spheroidal structure on the softened zone reduces the strength and increases the sensitivity of the ratchet.Thus reduces the life of the softened zone.The central area has the highest ratchet resistance,but its life is shortest due to the presence of non-metallic inclusions.The relationship between fatigue life and the ratcheting strain in the three regions is not uniform,and the fatigue life is paired with the stable the ratcheting strain rate of each region,and the life decreases with the increase of the ratcheting strain only for one region.The research results can provide the material parameters for the constitutive model of the rail welded joints.
作者
蒋文娟
王文健
丁昊昊
刘启跃
JIANG Wenjuan;WANG Wenjian;DING Haohao;LIU Qiyue(School of Materials Engineering,Sichuan Polytechnic University,Deyang 618000;State Key Laboratory of Rail Transit Vehicle System,Southwest Jiaotong University Chengdu 610031)
出处
《机械工程学报》
北大核心
2025年第8期116-126,共11页
Journal of Mechanical Engineering
基金
国家自然科学基金面上(52375205)
四川省国际科技创新合作(2023YFH0023)
轨道交通运载系统全国重点实验室自主研究课题(2024RVL-T02)资助项目。
