700 MPa级磁轭钢疲劳断裂行为表征与断裂评定

Fatigue fracture behavior characterization and fracture evaluation of 700 MPa grade yoke steel

对太钢生产的700 MPa级磁轭钢材料疲劳断裂过程进行了表征,采用ABAQUS软件模拟单次循环下试样的应力和应变场分布,同时采用红外热像仪对其疲劳过程的温度变化进行了监控,探究了疲劳过程中的变形行为,通过分析疲劳过程中700 MPa级磁轭钢表面温度演变规律,对疲劳极限进行了快速评定。结果表明,700 MPa级磁轭钢在疲劳过程中应力、应变均集中于标距处,其疲劳过程中的棘轮应变与温度演变规律相似,均分为3个阶段:初始升高阶段、平稳阶段以及最后断裂再次升高阶段。各循环应力下材料表面温度变化规律相同,并随着应力幅值增加,温度变化值增大。根据温度-应力变化关系得到700 MPa级磁轭钢材料的疲劳极限为309 MPa,与疲劳实验误差6%。

The fatigue fracture process of 700 MPa grade yoke steel produced by TISCO was characterized.The ABAQUS software was used to simulate the distribution of stress and strain fields of specimens under single cycle.At the same time,the infrared thermal imager was used to monitor the temperature change of the fatigue process,and the deformation behaviors during the fatigue process were explored.The fatigue limit was quickly evaluated by the evolution law of the surface temperature of 700 MPa grade yoke steel during fatigue process.The results show that the stress and strain concentration of 700 MPa grade yoke steel in the fatigue process are located at the gauge,and the ratchet strain in the fatigue process is similar to the temperature evolution law,which can be divided into three stages:the initial rising stage,the stable stage and the final fracture time in rising stage.The variation law of material surface temperature is the same under each cyclic load,and the temperature rise values increase with the increase of stress amplitude.According to the variation relationship of temperature-stress,the fatigue limit of 700 MPa grade yoke steel is 309 MPa,with an error of 6%compared with the fatigue experiment.