Surface integrity and fatigue performance of 17-4PH stainless steel after cutting operations

Abstract The 17-4PH stainless steel has been applied as a substitute of titanium to make jet engine parts, and fatigue life of the machined surfaces are very important due to its high reliability and safety demand. In this work, a series of experiments were conducted to investigate the impact of the cutting operations on the surface integrity, and its further influence on the fatigue life. It was confirmed that the fatigue performance of the machined surface was determined by the interactions of the surface integrity characteristics, including the work hardening, surface roughness and residual stress field. The softened layer under the machined surface and the compressive residual stress field were generated under all cutting conditions, resulting in the improved fatigue life when compared to the polished specimens. The plastic deformation and the resulting work hardening on the machined surface were enhanced continuously with an increase in each of the cutting parameters, which could cause significant decrease of the fatigue performance of the workpiece. The influence of surface roughness on the fatigue performance could be overshadowed by other surface integrity characteristics, since its effect was weakened by the curved feed marks generated on the face-milled surfaces. The cutting parameters could influence the fatigue performance of the machined components significantly by changing their surface integrity.