Vibration fatigue strength prediction of Precision-Milled ATI718 plus alloy Blades: Surface integrity and fatigue performance

The fatigue performance of blades plays a crucial role in determining the reliability of aeroengines. This study focused on precision-milled ATI718 Plus alloy compressor blades and established a vibration fatigue strength prediction method (VFSP-RR) based on the step-by-step approach. Surface integrity measurements and step-by-step vibration fatigue tests of the blades were conducted to explore the influence mechanism of surface integrity on fatigue performance. Experimental results indicated that the VFSP-RR method achieved a prediction accuracy exceeding 88.9% for blade vibration fatigue strength. The surface integrity of precision-milled blades exhibited significant anisotropy, with the maximum residual compressive stress and roughness in the blade height direction being 183.3% and 171.7% greater than those in the chord direction, respectively. Further computational analysis elaborated on the anisotropic effects of residual stress and roughness on fatigue performance: increasing the residual compressive stress in the blade height direction significantly improved the blade's fatigue life, whereas an increase in roughness in the blade height direction drastically reduced fatigue life. This study enhances the understanding of the relationship between surface integrity and fatigue performance in precision-milled blades, providing theoretical support and methodological references for fatigue-resistant blade manufacturing.