S30408 stainless steel laser weld joints: Microstructure evolution, performance and surface reinforced composites

The reinforced corrosion resistance composite coating was fabricated by laser cladding (LC) on the laser weld seam (WS) of S30408. The uniform microstructure, good tensile strength of WS and the LC coating were investigated, the mechanism of this LC coating reinforced the corrosion resistance of WS was extensively researched. The results revealed that WS consisted of face-centered cubic (fcc) austenite, and body-centered cubic (bcc) ferrite. The LC coating consisted of fcc. Amounts of the granular precipitates were distributed near the ferrites in WS. The tensile strength of WS was increased due to the synergistic effect of the solution/fine grain strengthening. Corrosion resistance of the LC coating was higher than that of the weld seam. Passivation films were produced due to the chemical reaction between Co/Cr/Fe and water/oxygen.