Improving the fatigue property of diffusive film cooling holes in nickel-based single crystal superalloy via ultrashort pulse laser drilling coupled with abrasive flow machining

• Published in: Journal of materials processing technology 2024-07, Vol.328, p.118411, Article 118411
• Main Authors: Zhang, Zhanfei, Mao, Zhong, Wang, Wenhu, Xie, Huimin, Jiang, Ruisong, Xiong, Yifeng, Zhang, Xiaobing
• Format: Article
• Language: English
• Subjects: Abrasive flow machining; Diffusive film cooling hole; Fatigue property; Single crystal superalloy; Surface quality; Ultrashort pulse laser
• ISSN: 0924-0136
• DOI: 10.1016/j.jmatprotec.2024.118411

A novel hole-making technique, which combines ultrashort pulse (UP) laser drilling with abrasive flow machining (AFM), has been developed to enhance the surface quality and fatigue resistance of diffusive holes in nickel-based single crystal (NBSC) superalloys. This study conducted a comprehensive analysis of the surface morphology and metallurgical characteristics of the hole wall, evaluated by fatigue testing at elevated temperatures and fractography analysis. The findings demonstrate that AFM can effectively eliminate the solidified debris generated during UP laser drilling, significantly reducing surface roughness and inducing a rounded effect at the outlet acute zone of the diffusive hole. Such improvements have been shown to increase the fatigue life of the holes by up to 50.6 % compared to those without polish. Furthermore, the crystal plasticity finite element method (CPFEM) was employed to investigate the localized stress concentration and the accumulation of plastic slip around the diffusive hole, elucidating the mechanisms behind fatigue failure in NBSC superalloys. The study also discusses the influence of the different hole-making technology on the fatigue properties of diffusive holes, integrating CPFEM results with analyses of surface quality and fatigue fractography. The study conducted in this study can provide valuable guidance for the fabrication of diffusive holes in turbine blades. Furthermore, it can also improve our understanding of the fatigue failure mechanism of diffusive holes in NBSC superalloy. [Display omitted] •A hole-making technology for diffusive hole that includes UP-laser drilling coupled with abrasive flow machining was proposed.•The composite technology can reduce the hole-wall roughness and improve the fatigue life of diffusive holes.•CPFE simulation revealed that the large accumulated plastic strains on stress concentration zone caused the final failure.•The influence mechanism of hole-making technologies on the fatigue behavior of diffusive holes was discussed.