Q235钢结构材料的超低周疲劳性能

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1 Hz 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。

Extremely low cycle fatigue properties of steel structure materials Q235

Extremely low cycle fatigue (ELCF)properties of the steel structure material Q235 were investigated. The ELCF tests were conducted on a Shimadzu servo-hydraulic testing machine under transverse strain control with frequency of 1 Hz.The experimental data including cyclic stress response characteristics of the test material were obtained.Accordingly,the ELCF life prediction models based on both the plastic strain and strain rate were established,respectively,and the ELCF life could be predicted well by both the life prediction models.Later,the micro-fracture mechanism in ELCF of the test material was analyzed by using the scanning electron microscope (SEM).The results show that there are some differences between ELCF and low cycle fatigue of the test material in the fatigue properties,such as the cyclic stress response characteristics,life prediction models and micro-frac-ture mechanisms.