Effect of shot peening on fatigue behavior and microstructure of additively manufactured Co-Cr-Mo alloy

Abstract

This investigation delved into the impact of shot peening on the fatigue properties of Co-Cr-Mo samples manufactured through laser powder bed fusion. Two primary groups were established, one subjected to stress relief heat treatment. Each group underwent further division, with one subgroup undergoing shot peening. Comprehensive microstructural, fractographic analyses and fatigue tests were conducted. Statistical analysis of fatigue results demonstrated a noteworthy difference (p < 0.05) between machined and shot-peened samples across stress levels of 700–70, 600–60, and 500–50 MPa. A statistical significance was observed between machined and heat-treated, then machined samples within 700–70 and 600–60 MPa stress levels. Fatigue analysis of heat-treated, then machined samples revealed a shorter life comparing with machined samples at low cycle fatigue (<105), but superior performance at high cycle fatigue (>105). Fracture surface examinations indicated a planar structure with a distinctive quasi-cleavage texture, affirming that shot peening enhances fatigue behavior by refining mechanical properties.