Fatigue performance improvement of laser shock peened hole on powder metallurgy Ni-based superalloy labyrinth disc

Abstract

It is well understood that the components with holes used in aviation and aerospace industries are generally vulnerable to alternate cycles of working stress during their service, which are weakest parts and highly prone to failure and fracture due to the stress concentration at the edge of hole. To improve the resistance towards fatigue failure of the hole, laser shock peening (LSP) technology is successfully applied to the hole on powder metallurgy (P/M) Ni-based superalloy labyrinth disc in present work and significant 18% increase in high cycle fatigue limit is achieved (from 224 ± 4 MPa to 265 ± 6 MPa). The notable effects of LSP on the residual stress, microhardness and microstructure of the hole with and without LSP is investigated based on experimental and simulation method. It is found the large improvement of fatigue limit is attributed to the comprehensive action of high amplitude compressive residual stress and microhardness, grain refinement and the removement of inclusions caused by LSP. The finding here in promoting the fatigue resistance of hole by LSP are general and flexible, thereby exhibiting a potential application to a wide spectrum of engineering components with hole structures.