2050铝合金的疲劳裂纹扩展行为研究

研究取样方向、应力比以及微观组织对2050铝合金疲劳裂纹扩展速率的影响。结果表明:取样方向和应力比对疲劳裂纹扩展速率在近门槛区和快速扩展区的影响显著,而在稳态扩展区的影响则相对较小;L-T取样方向的速率最低,T-L取样方向的速率次之,S-L取样方向的速率最高,这主要与合金的晶粒取向、织构取向和第二相粒子取向有关;应力比为0.5的裂纹扩展速率高于应力比为0.1的速率,这在近门槛区主要与裂纹闭合效应有关,在快速扩展区主要受最大应力场强度因子Kmax的影响。

Fatigue Crack Propagation Behavior of 2050 Aluminum Alloy

The influence of sampling orientation, stress ratio and microstructures on the fatigue crack propagation behavior of 2050 aluminum alloy was investigated. The results show that the effects of sampling orientation and stress ratio on the crack propagation rates are quite significant in the near-threshold region and the stable-tearing crack growth region, while their effects are relatively small in the stable growth region. The fatigue crack growth rate in L-T orientation is the lowest, followed by the rate in T-L orientation, and the rate in S-L orientation is the largest. The effect of sampling orientation on the fatigue crack growth rate mainly depends on grain orientation, texture orientation and the orientation of second phase particle. The fatigue crack growth rate of stress ratio 0.5 is bigger than that of stress ratio 0.1, which are mainly related to the crack closure effect in the near-threshold region and remarkably influenced by the maximum stress intensity factor Kmax in the stable-tearing crack growth region.