采用扫描电子显微镜(SEM)观察不同工艺参数下飞秒激光加工镍基单晶合金DD6气膜孔的形貌, 主要考虑不同离焦量、不同单脉冲能量下气膜孔的孔径、锥度和圆度误差。实验结果表明: 当离焦量由零转为正或负时, 上孔径和锥度会增大, 而下孔径则会减小; 当离焦量由负变正时, 圆度误差变大; 当单脉冲能量逐渐增大, 孔直径越大, 锥度则会减小, 圆度误差逐渐增大。当加工时间为30min, 离焦量为0, 单脉冲能量为100μJ时, 孔锥度达到最佳值。

In this work, femtosecond laser drilling process of nickelbased single crystal alloy DD6 was studied. The aperture, taper and roundness error of film cooling holes in DD6 alloy under different femtosecond laser process factors, including defocusing amount and pulse energy, were characterized by SEM. Experimental results demonstrate that when the defocusing amount deviates from 0 either to the positive or the negative direction, taper and upper aperture of the holes increase, but lower aperture decreases. With the focus moving from the inside (positive) to the outside (negative) of the sample, the roundness error gradually increases. With larger single pulse energy, the diameter as well as roundness error become larger and the taper becomes smaller. When the defocusing amount is 0, the taper of the holes processed by femtosecond laser with 100μJ pulses energy after machining 30min is the best.