Effect of Laser Shock Peening on the Fatigue Life of Inconel 792 Superalloy After High‐Temperature Hot‐Corrosion Exposure in a Molten‐Salt Environment

Abstract

ABSTRACT This study investigated the effect of laser shock peening (LSP) on the fatigue behavior of Inconel 792 nickel‐based superalloy after exposure to hot corrosion. Specimens were first subjected to corrosion in a molten salt bath containing 75 wt% Na 2 SO 4 + 15 wt% NaCl + 10 wt% V 2 O 5 at 700°C and were subsequently fatigue‐tested at room temperature. LSP‐treated specimens processed at different repetition rates were comprehensively evaluated to assess surface integrity, residual stress, and microstructural evolution. The results demonstrated that LSP generated a substantial compressive residual stress field and promoted grain refinement near the treated surface. Maximum surface hardness increased by approximately 27%, and fatigue life improved by about 2.5 times in air and 2.46 times after hot‐corrosion exposure compared with untreated specimens. The improved performance was mainly attributed to delayed surface crack initiation and a shift in the crack origin from the surface to the subsurface. Despite the aggressive high‐temperature corrosion environment, LSP‐treated specimens exhibited greater resistance to oxidation‐related damage and maintained improved protection against hot corrosion, owing to the stability of the compressive residual stress field and the hardened surface layer.