研究目的
To study the fabrication process of film cooling holes on the single crystal superalloy DD6 plate specimen by ultrafast laser, focusing on the effects of laser process paths and process parameters on the geometric precision and surface quality of microholes.
研究成果
The study concludes that concentric circular scanning path provides the best surface quality for microholes. Focus position has the most significant influence on geometric precision and surface quality, with positive defocus distance leading to smaller taper, roundness, and surface roughness. Microholes machined by ultrafast lasers exhibit no defects such as recast layer, microcrack, or heat-affected zone, except for solidified debris at the hole entrance. The research suggests combining larger mean power, positive defocus distance, smaller scanning velocity, and larger scanning width for higher precision and quality of microholes.
研究不足
The study focuses on the geometric precision and surface quality of microholes machined by ultrafast laser on nickel-based single crystal superalloy DD6. The findings may not be directly applicable to other materials or laser machining techniques. The influence of some process parameters like scanning velocity and blowing pressure was found to be negligible, suggesting areas for further optimization.
1：Experimental Design and Method Selection:
The study compared three different scanning paths (concentric circular scanning, linear scanning, and linear + circular scanning) for laser drilling. The concentric circular scanning path was selected for further experiments due to its superior surface quality. The influence of process parameters (mean power, scanning velocity, focus position, scanning width, and blowing pressure) on microhole quality was analyzed.
2：Sample Selection and Data Sources:
The material used was nickel-based superalloy DD6. The geometric precision and surface quality of microholes were measured using a three-dimensional surface profilometer and scanning electron microscopy.
3：The geometric precision and surface quality of microholes were measured using a three-dimensional surface profilometer and scanning electron microscopy.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A diode-pumped solid laser (Altantic series) with a wavelength of 1030 nm and a pulse width of 2.1 ps was used. The beam was focused by a lens with a focal length of 150 mm. The process was assisted by coaxial gas blowing and observed in real time with a CCD camera.
4：1 ps was used. The beam was focused by a lens with a focal length of 150 mm. The process was assisted by coaxial gas blowing and observed in real time with a CCD camera.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The study involved selecting the optimal scanning path, then investigating the influence of process parameters on microhole quality. Each test was repeated six times for reliability.
5：Data Analysis Methods:
The geometric precision was measured using the least square method and the minimum zone method. Surface roughness was evaluated using the contour arithmetic mean deviation Ra.
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