Study on the Effects of Multiple Laser Shock Peening Treatments on the Electrochemical Corrosion Performance of Welded 316L Stainless Steel Joints

Abstract

To study the influence of laser shock peening on the electrochemical corrosion resistance of welded 316L stainless steel joints, welded 316L stainless steel joints are treated with different laser shock peening treatments (i.e., one, two, and three times). Our analysis employs electron backscattering diffraction (EBSD), scanning electron microscopy (SEM), X-ray diffraction (XRD), an X-ray stress meter, and electrochemical corrosion tests to observe and analyze the microstructure, structural composition, residual stress, and corrosion resistance in different areas of the surface of 316L before and after the laser shock peening. The results show that the residual stress distribution of the welded joints is optimized after laser shock peening, with a maximum residual compressive stress near the matrix of 171 MPa. When the number of laser shock peening treatments is two, the corrosion current reaches a minimum of 9.684×10−7 A/cm2, and optimal pitting resistance is obtained. However, when the number of laser shock peening treatments is further increased to three, the corrosion current increase and the pitting resistance decreases. In summary, the electrochemical corrosion resistance of the welded joints effectively improves after laser shock peening, but its performance begins to decline after three repeated shocks, which is related to the combined effects of stress change and microstructure phase transformation.

Review on Anti-Fatigue Performance of Gradient Microstructures in Metallic Components by Laser Shock Peening

“…The high-cycle fatigue strength of the specimens increased by 19.82%, which was similar to the result of a 26% increase in the fatigue life of TIG-welded pure titanium [71]. Zhou et al [33] investigated multiple LSP treatments on welded joints of 316 L stainless steel, and the introduction of residual stresses improved the pitting resistance of the specimens. NIE et al [72] investigated a double-sided LSP-treated TA15 TIG head to solve the problems of welding penetration depth and fatigue degradation after double-sided welding.…”

“…The number of laser processing times Multiple shocks affect the residual compressive stress and the depth of action [33,34] This review takes titanium alloy, nickel-based superalloy, and other typical structural component materials as research objects, and engine fan/compressor blades, high-temperature components, thin-walled weldments, and other components with high failure rates as application cases. The research results on the application of LSP on aeroengine components are systematically summarized, focusing on the characteristics of LSP-induced surface nanocrystallization of metal materials, residual stress characteristics, formation principles, thermal stability, fatigue resistance mechanism, and process methods, etc.…”

Insights into the Response Differences of Ultrasonic Rolled A3 Carbon Steels and 316L Stainless Steels to Scale and Wax Precipitation Behavior

“…Till now, many mechanical surface treatment techniques, including shot peening (SP), laser shock peening (LSP), and ultrasonic nanocrystal surface modification (UNSM), deep rolling, have been developed to achieve the surface modification of metallic materials. [ 17–20 ] However, some negative aspects supplied the influence from uneven surface and some microcracks could destroy the surface finish of the sample. [ 19,21 ]…”

Laser Shock Peening Improves the Corrosion Resistance of an E690 High-Strength Steel Cladding Layer

“…The surface current density was reduced by 98.1% and the pitting potential was increased by 89.5%. Numerous studies by scholars have shown that laser shock peening can cause plastic deformation of metal materials [ 11 , 12 ], proliferation of internal dislocations, precipitation and grain refinement [ 13 , 14 , 15 ], and increase the corrosion resistance of materials.…”