Effect of Laser Shock Peening on the Stress Corrosion Cracking of Inconel 792

Abstract

This study investigated the stress corrosion cracking (SCC) behavior of the IN792 superalloy following laser shock peening (LSP) treatment. Slow strain rate tension (SSRT) testing was conducted in a simulated marine environment to assess SCC susceptibility. The influence of varying LSP spot sizes on microstructure, residual stress, and microhardness was characterized using optical microscopy (OM), x-ray diffraction (XRD), and microhardness measurements. Specimens were coated with a salt mixture comprising 75% Na2SO4, 15% NaCl, and 10% V2O5 (wt.%) and exposed to 700 °C for 100 hours in a furnace environment. Mechanical testing was performed on an SSRT apparatus at a strain rate of 10−5 s−1. Scanning electron microscopy (SEM) was employed to examine the fracture surface morphology. LSP treatment shifted the residual stress from 235 MPa to − 290 MPa, introducing compressive residual stresses to a depth of ~ 1 mm and altering surface morphology and microhardness. Microhardness increased by 30%, grain size decreased by 62%, and ultimate tensile strength (UTS) improved by 18% relative to untreated specimens. These results demonstrate that LSP markedly improves the high-temperature SCC resistance of IN792.