Microstructural evolution and pitting corrosion behavior of friction stir welded joint of high nitrogen stainless steel

With the achievement of sound joints of high nitrogen stainless steel via friction stir welding, significant micro structural changes take place in various regions of the joints. This would bring out the change in the corrosion properties of the joints. In this study, the corrosion behavior of friction stir welded joint of high nitrogen stainless steel was investigated using electrochemical and immersion tests. No drastic decrease in breakdown potentials was observed in the heat affected zones with number and size distribution densities of pits being similar to that in the base metal. The nugget zone exhibited a relatively good pitting corrosion resistance, mainly attributing to the breakup of coarse inclusions and grain refinement during welding. The delta-ferrite bands and tool wear exerted no obvious effects on the corrosion behavior of the welded joint due to the lack of Cr diffusion. (C) 2016 Elsevier Ltd. All rights reserved.