FGH96合金疲劳裂纹扩展过载迟滞行为研究

Fatigue Crack Growth with Overload Retardation Effects in FGH96 Alloy

针对FGH96粉末高温合金,开展了500℃和700℃不同过载比下的疲劳裂纹扩展过载迟滞行为试验,分析了试验温度、过载比等对FGH96合金裂纹扩展过载迟滞行为的影响,对其疲劳裂纹扩展过载迟滞行为进行了预测分析。结果表明:对于FGH96合金,过载比越大,过载迟滞效应越明显,相同过载比时700℃下的过载迟滞效应比500℃更为明显。过载比分别为1.2和1.4时,过载迟滞效应不明显,广义Willenborg模型、改进的广义Willenborg模型以及修正Willenborg模型的预测结果差别不大,与试验结果差别也不大。过载比为1.6时,过载迟滞效应明显,修正Willenborg模型对裂纹扩展曲线的预测结果与试验结果较为吻合,裂纹扩展寿命预测误差小于10%,广义Willenborg模型和改进的广义Willenborg模型对裂纹扩展曲线的预测结果接近,与试验结果差别较大,裂纹扩展寿命预测结果与试验结果差别也较大。

Experiments were conducted to investigate the overload retardation behavior of fatigue crack growth in FGH96 powder superalloy at 500℃and 700℃under different overload ratios.The effects of test temperature and overload ratio on the crack growth overload retardation behavior of FGH96 alloy were analyzed,and the fatigue crack growth overload retardation behavior of FGH96 was predicted and analyzed.The results show that for FGH96 superalloy,the greater the overload ratio,the more pronounced the overload retardation effect.At the same overload ratio,the overload retardation effect at 700℃is more pronounced than at 500℃.When the overload ratios are 1.2 and 1.4,the overload retardation effect is not significant,and there is little difference between the predictions of the generalized Willenborg model,the modified generalized Willenborg model,and the modified Willenborg model,as well as the experimental results.When the overload ratio is 1.6,the overload retardation effect is significant.The prediction results of the modified Willenborg model for the crack growth curve are in good agreement with the experimental results,with a crack growth lifetime prediction error of less than 10%.The predictions of the generalized Willenborg model and the modified generalized Willenborg model for the crack growth curve are similar and differ significantly from the experimental results,leading to larger differences in crack growth lifetime predictions compared to the experimental results.