Effect of heat input on microstructure and corrosion resistance of high-nitrogen austenitic stainless steel welded joints

Abstract

Abstract In this study, the microstructure and corrosion resistance of high-nitrogen austenitic stainless steel welded joints with different heat inputs were investigated. A high heat input leads to a large width and depth of the fusion pool and a low fraction of δ-ferrite in the weld sea. However, a high fraction of Cr-rich precipitates is formed under a high heat input and low heat promotes the formation of δ-ferrite. Therefore, following corrosion tests, the weld seam suffers severe intergranular corrosion under high heat input and low heat input, and the corrosion resistance of the weld is the highest at a heat input of 6.8 kJ/cm. A high heat input results in a high fraction of Cr-rich precipitates and a random boundary in the heat affected zone (HAZ), which decreases corrosion resistance. Furthermore, corrosion test results indicate that the Cr-depleted area and random boundary are initially corroded, and high heat input decreases corrosion resistance of the HAZ.