Determination of laser shock treatment conditions for fatigue testing of Ni-based superalloys

Abstract

It is envisaged that laser shock surface treatment may be used to surface harden and improve the mechanical properties of materials by inducing compressive stresses. This study deals with its application to the high performance aeronautical Ni-based superalloy Astroloy for turbine discs and its effect on low-cycle fatigue resistance. X-ray diffraction was used to measure the surface and in-depth stress distributions. The prominent features of laser shock processing have been studied by an analytical approach to the main physical phenomena occurring successively during the impact. This led to an adequate treatment of conventionnal cylindrical low-cycle fatigue specimens. Fatigue tests were then conducted on Astroloy at 550 o C. These showed the beneficial effect of laser shock processing