Investigation of Microhole Quality of Nickel-Based Single Crystal Superalloy Processed by Ultrafast Laser

The geometric accuracy and surface quality of thin-film cooling holes have a significant impact on the cooling efficiency and fatigue life of aeroengine turbine blades. In this paper, we conducted experimental research on the processing of nickel-based single-crystal high-temperature alloy DD6 flat plates using different femtosecond laser processes. Our focus was on analyzing the effects of various laser parameters on the geometric accuracy results of microholes and the quality of the surfaces and inner walls of these holes. The results demonstrate that femtosecond laser processing has great influence on the geometrical accuracy and surface quality results of film cooling holes. Notably, the average laser power, focus position, and feed volume exert a significant influence on the geometric accuracy results of microholes. For instance, a higher laser power can damage the microhole wall, thereby leading to the formation of tiny holes and cracks. Additionally, microholes exhibit optimal roundness and taper values when using a zero defocus volume. Moreover, increasing the feed distance results in enhanced entrance and exit roundness, whereas scanning speed has a negligible impact on microhole roundness.