Improvement in Mechanical and Corrosion Properties of Laser and electron Beam Welded AISI 304 Stainless Steel Joints by Laser Shock Peening

In this work, the effects of laser shock peening (LSP) on various 0properties of weld joints of AISI 304 stainless steel obtained by laser beam and electron beam welding are reported. Laser beam welding was carried out at speeds in 2.4–4.0 m/min range and 2 kW laser power. The effect of welding speed on the melt pool thermal characteristics and various physical and mechanical properties were investigated. Similarly, the influence of electron beam scan speed on the weld microstructure, mechanical properties, and corrosion resistance was studied in the 1.0–1.6 m/min range at a constant line energy. LSP performed underwater confinement at ~ 4.5 GW/cm² laser power density using a Q-switched Nd: YAG laser operating at 1064 nm wavelength induced a significant amount of compressive residual stress. The yield strength of LBW and EBW specimens improved by 29% and 18.4%, respectively, due to the strain hardening and twining effect of LSP. With the application of LSP, the fatigue life increased by nearly four and six times for the LBW and EBW specimens, respectively. The microhardness increased by around 12–14% for LBW and 6–10% for EBW specimens, respectively, in the weld zone. LSP also improved electrochemical corrosion resistance by reducing the corrosion current densities of LBW and EBW welded specimens by up to 77.93% and 51.21%, respectively. The induced compressive residual stresses have led to reduced pitting potential in both EBW and LBW specimens.