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对钢结构材料Q235钢的超低周疲劳性能进行了研究。采用横向应变控制方法,保持频率1Hz恒定,在岛津电液伺服疲劳试验机上开展了试验钢的超低周疲劳试验。获得了循环应力响应特征曲线等实验数据,并在此基础上分别建立了试验钢基于塑性应变幅及应变速率的超低周疲劳寿命预测公式,且2种公式均能较好地对其寿命进行预测。通过电镜扫描(SEM),分析了试验材料超低周疲劳下的微观断裂机理。研究结果表明,试验材料在超低周疲劳与低周疲劳下的疲劳性能,如循环响应特征、寿命预测公式以及微观断裂机理等方面均存在一定的差异。
The low cycle fatigue properties of Q235 steel were studied. The lateral strain control method was adopted to maintain the constant frequency of 1Hz. The ultra-low cycle fatigue test of the test steel was carried out on the Shimazu electro-hydraulic servo fatigue testing machine. The experimental data of cyclic stress response curves and other experimental data were obtained. Based on this, the formulas for predicting the ultra-low cycle fatigue life of the test steel based on the plastic strain amplitude and strain rate were established respectively, prediction. The microscopic fracture mechanism of the test material under ultra-low cycle fatigue was analyzed by scanning electron microscopy (SEM). The results show that there are some differences in the fatigue properties of the test materials under ultra-low cycle fatigue and low cycle fatigue, such as cyclic response characteristics, life prediction formula and microscopic fracture mechanism.