Al－Li合金缺口疲劳短裂纹行为的研究

研究了不同时效状态的Ａｌ－Ｌｉ合金短裂纹的扩展规律，缺口曲率半径对短裂纹扩展规律的影响．在相同的时效温度下，裂纹扩展速率ｄａ／ｄＮ随时效时间增加而加快；钝缺口萌生裂纹的ｄａ／ｄＮ在缺口应力场内变化不大，然后随着应力强度因子的增加而逐渐变大，而锐缺口萌生裂纹的ｄａ／ｄＮ在裂纹萌生后很快下降到最小值，然后又逐渐回升．

SHORT NOTCH CRACK BEHAVIOR OF Al-Li ALLOYS

The short crack propagation behavior in 8090 Al-Li alloys at various aged conditions (underaged, peakaged, overaged, naturallyaged) and the effects of the notch radius on the short crack propagation have been studied. The results show that the fatigue crack propagation rate increases, the fatigue threshold value decreases with increasing aging time. The growth rate of short crack which initiated from the blunt notch rates is nearly stable within the notch stress field, then converges with that of the long crack gradually. The growth rate of short crack which initiated from the sharp notch decreases with that of the crack length to the minimum rapidly and then increases, to converge with that of the long cracks gradually.Correspondent: SHAN Zhaohui, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015