Microstructure and Corrosion Resistance of Friction Stir Welded High Nitrogen Stainless Steel Joint Available to Purchase

The corrosion resistance of a friction stir welded high nitrogen stainless steel joint was evaluated by immersion corrosion tests. The heavily corroded thermomechanically affected zone (TMAZ) was determined to be the weakest zone of the joint. The TMAZ, as a distinct transitional region with partial recrystallization, exhibited a nonuniform microstructure consisting of coarse and fine grains and an inhomogeneous strain distribution with high strain in fine grain regions. A higher corrosion rate was confirmed via electrochemical analyses, which was mainly attributed to the high defect density, galvanic corrosion, and the formation of Cr-rich particles.