不同过载比下B780CF钢疲劳裂纹扩展速率的试验研究

Experiment Study on Fatigue Crack Growth Rate of B780CF Steel Under Different Overload Ratios

采用紧凑拉伸试样进行六级过载比(1.0、1.5、1.75、2.0、2.2、2.5)下的疲劳裂纹扩展速率试验,得到了不同过载比下的裂纹扩展速率曲线。对四级过载比下(1.5、1.75、2.0、2.2)的疲劳断口进行分析,分析了过载比对疲劳寿命和裂纹扩展速率的影响。结果表明:过载比越大,达裂纹扩展速率越慢。随着过载比的增大,单个拉伸过载引起的迟滞效应更加明显。

Using a compact tensile specimen , the fatigue crack growth rate test was carded out under six stage overload ratios （1.0, 1.5, 1.75, 2, 2.2 and 2.5）, and the crack growth rate curve can be obtained under different overload ratios. The fatigue fractures under four overload ratios （1.5, 1.75, 2.0, 2.2） were analyzed. The effects of overload ratio on the fatigue life and crack growth rate were analyzed.The results show that the greater the overload ratio, the slower the crack growth rate. With the increase of overload ratio, the hysteresis effect caused by single tensile overload is more obvious.