激光冲击处理降低铝合金裂纹扩展速率的研究

Study on Laser Shock Processing to Decrease the Fatigue Crack Growth Rates of Aluminium Alloy

采用 3.0mm厚的LY12 (2 0 2 4 )T6 2薄板制作成紧凑拉伸试件 ,在试件的预制裂纹延长线上进行三次搭接激光冲击处理 ,然后进行裂纹扩展速率试验并与未处理试件进行对比。由于激光冲击处理产生的强化效应在裂纹扩展路径上存在区域差别 ,所以裂纹扩展速率无法进行Paris公式拟合 ,但在整体上能大大降低裂纹扩展速率 ,在某些强化区还能明显提高应力强度因子门槛范围值。

Compact tension(CT) specimens of 2024T62 sheet with thickness of 3.0?mm are shock processed by intense pulse laser,three spots overlapped along the extension line of precut crack.The fatigue crack growth rates of laser shock processed specimens are compared with those without laser shock processing,and the results show that effects of laser shock strengthening have much difference along the crack growth line,the fatigue growth rates can not be fitted by the Paris formula,but laser shock processing can decrease the fatigue crack growth rates on the whole and improve the threshold of stress intensity factor range in some strengthened zone.