Effect of severe shot peening on the fatigue life of the laser-cladded Inconel 718 specimens

This paper presents the influence of the severe shot peening process on the fatigue life of the laser-cladded Inconel 718 specimens which can be employed during refurbishment of components enduring high mechanical cyclic loads such as gas turbine components. In order to quantitatively evaluate the destructive effect of laser cladding on the fatigue endurance, fatigue tests are first performed on the as-received and laser-cladded specimens. Then, microstructural analysis by scanning electron microscope (SEM) is carried out to identify the root causes of the drawback of laser cladding. Moreover, by employing a comprehensive laser-cladding FE analysis considering cyclic plastic material modeling, the induced residual stress distribution is determined. To decrease the detrimental effects of laser cladding on the microstructure and residual stresses, the specimens are next subjected to severe shot peening treatment, and then, extra sets of fatigue tests are conducted on the specimens. The conducted experiments show that the laser cladding can cause the deterioration of the fatigue life of the specimens at about 40%, and the damaged fatigue life can be almost restored by the severe shot peening. The experiments also indicate that the clad-toe zone is the weakest area concerning fatigue issues in laser-cladded specimens with or without shot peening post-process. Hence, the clad-toe zone needs some special attention.