Review of using laser peening to mitigate hydrogen-induced mechanical and fatigue properties degradation in metallic alloys

Although hydrogen energy has been touted as the promising clean energy solution to the escalating global energy demand, the issue of hydrogen embrittlement (HE) of metallic alloys remains a key challenge that has limited its full deployment. Surface deformation techniques have been utilized within the last two decades as HE mitigation measures, for which laser peening (LP) technology has been known to achieve great results. This review discusses the effect of LP-produced compressive residual stresses (CRS), grain refinement, and dislocations on the HE mitigation in metals by looking at the outcome of LP on hydrogen diffusivity, microhardness, tensile properties, and vibration fatigue properties of hydrogenated metallic alloys. The anti-HE mechanism of LPed metallic alloys was also discussed, and some prospective research directions on the topic were subsequently proposed. This paper can serve as a reference for researchers in the area of HE mitigation research.