Experimental study of nickel-based superalloy IN792 with femtosecond laser drilling method

The improvement of aircraft engine performance resulted in the highly demand of drilling micron-sized holes (<1 mm) into the blades. A two-step approach with an axial feed method for nickel-based superalloy IN792 femtosecond laser drilling was studied. The effects of different processing path parameters on the hole quality are described and discussed in detail. The drilling strategy containing a drilling through phase and an enlargement phase, which was able to produce cylindrical holes with diameters of 600 μm on 680 μm and 1300 μm thick plate without modification and reconstruction of the processing platform. According to the different material thickness, the corresponding drilling optimization strategy was proposed. The experiments showed that the hole quality processed using the two-step method improved obviously compared with the one-step method, including that the outlet circularity can be increased by 7.4% and the taper angle can be reduced by 4°. Moreover, there is no obvious heat-affected zone (HAZ), recast layer or micro-cracks on the hole surface and wall. In conclusion, the two-step approach is an effective hole processing method that provides the possibility of high-efficiency and high-quality machining of film cooling holes.