The Effect of Heat Input and Shielding Gas Composition on Corrosion Resistance of TIG Weld Metal of New Lean Duplex Stainless Steel S82441

Abstract

The effects of TIG welding and post-treatment procedures on the microstructure and the pitting corrosionresistance of welded lean duplex stainless steel S82441 were investigated. Autogenous TIG welding wasused with different amounts of heat input and shielding gases such as Ar, and mixtures of Ar-N2 and Ar-He. The addition of 5% to 15% of nitrogen to argon practically did not affect the level of the pitting corrosionresistance. However, the application of gas mixtures (50% Ar + 50% He) resulted in a significant decreasein pitting corrosion resistance. We found that increased current (200 A and 250 A) led to lower valuesof CPT of welds compared with welds obtained with 50 A, 100 A and 150 A. In addition, the removalof the weld surface layer (0.2 ~ 0.3 mm thickness) in most cases not only resulted in a significant increasein resistance to the pitting corrosion but also post-treatment of weld, implying that corrosion resistancedepended on factors such as surface roughness or the presence of undesirable oxides.