A study on the surface morphology evolution of the GH4619 using warm laser shock peening

Abstract

Compared with the laser shock peening, the warm laser shock peening has been demonstrated to get a stable compressive stress distribution under heating and cyclic loading, which is mainly due to warm laser shock peening combined with the advantages of laser shock peening and dynamic strain aging. The surface morphology evaluation of warm laser shock peening was investigated systematically in this work, the GH4169 nickel-base super-alloy is selected as the material with which to conduct experiments of laser shock peening and warm laser shock peening. It can be found that there are a lot of surface ripples appearing after the treatment of warm laser shock peening, which is different from the surface reliefs by the treatment of laser shock peening. Under high temperature and strain rate, δphase transformed into γ″ phase. Simultaneously, compared with the δphase of the larger grain size, the grain size of γ″ phase is much smaller, and is unable to form the surface relief. Warm laser shock peening produced a higher dislocation density and more stabilized dislocations that are pinned by the "Cottrell Clouds" formed by γ″ phase, which can inhibit the residual stress failure at the high temperature-alternating load.