一种Al-Cu-Mg-Zr合金的疲劳裂纹扩展行为研究

研究热处理状态、应力比和试样取向等对含Zr的Al-Cu-Mg系铝合金疲劳裂纹扩展行为的影响.结果表明,T3、T4两种热处理状态试样的疲劳裂纹扩展速率没有明显差别;L-T方向和T-L方向的试样也有大致相同的疲劳裂纹扩展速率;应力比R对疲劳裂纹扩展行为有明显影响,高应力比下的疲劳裂纹扩展速率明显快于低应力比条件下的扩展速率,并且高应力比下的疲劳裂纹扩展在较小的△K值下进入快速扩展阶段,并很快断裂.在较低的△K水平下应力比的影响与裂纹闭合效应有关.

Fatigue Crack Propagation Behavior of Al-Cu-Mg-Zr Alloy

The influence of heat treatment, specimen orientation and stress ratio on the fatigue crack propagation behavior of Al-Cu-Mg alloy containing Zr was studied. The results show that the difference of fatigue crack propagation rates between T3 and T4 temper specimens was not obvious. The effect of specimen orientation on the crack propagation rates was less significant. The fatigue crack propagation rates of the specimens in the L-T orientation and T-L orientation were similar. However, the stress ratio had a remarkable influence on the fatigue crack propagation rates; at the higher stress ratio, the fatigue crack propagation rates increased and the fatigue crack propagated rapidly into the high crack propagation regime to failure at lower ?K levels. The effect of stress ratio at near-threshold levels could be explained by a crack closure concept