镍 基 高 温 合 金 喷 油 孔 的 飞 秒 激 光 精 密 加 工

Femtosecond laser planar spiral drilling strategies offer several advantages, such as flexibility, precision, and process efficiency, making it possible to achieve high machining accuracy for specific types of aerospace engine oil supply nozzle. Therefore, in this study, we adopted a femtosecond laser helical drilling method and systematically investigated the effects of laser power, single layer feed, single layer scan time, defocusing amount, and pulse repetition rate on the quality of drilling. The defocusing amount has significant influence on the inlet diameter, while power and feed are the parameters affecting the outlet diameter the most; processing efficiency heavily depends on power. Considering these aspects, through-holes with a hole size of 390 μm were successfully prepared on GH3044 sheets with a thickness of 1. 5 mm. The errors for inlet-outlet diameters and taper were less than 0. 6 μm and 0. 5°, respectively. Using the statistical analysis of the variation law of hole wall roughness under different parameters, it was found that the roughness value can be effectively reduced to Sa = 0. 6 μm, which exceeds than the process requirement, by simply adjusting parameters. Moreover, the analysis of the hole wall morphology showed that the drilling quality was excellent. By increasing the laser pulse repetition frequency, the microstructure near the hole wall gradually coarsens. However, there is no obvious recast layer or heat-affected zone, which is necessary to realize the relatively“cold”processing for high-precision micro holes. This study provides a theoretical basis for the fabrication of special-shaped micro holes using the high atomization effect.