Effects of laser welding on the microstructure evolution and corrosion resistance of a novel nitrogen-containing austenitic stainless steel QN2109

After laser welding, the corrosion resistance and microstructure of a newly developed austenitic stainless steel, QN2109, were investigated. A negligible heat-affected zone was found and the segregation of Cr, Mo, Mn, Ni, and N was revealed by EPMA. In contrast to previously reported findings, the corrosion resistance of δ-ferrite obtained here was lower than that of austenite in acidic solutions revealed by SKPFM and MFM, owing to N segregation. The pitting resistance of whole welds was lower than that of base metal (BM), whereas the pitting resistance of the fusion zone was higher than that of BM, owing to the significant decrease in the number of inclusions.