New insights into metallurgical, corrosion, passive film and fatigue characteristics of AISI 316L submerged arc welded joints

Abstract

Submerged arc welded AISI 316L butt weld was investigated to understand its metallurgical, corrosion, passive film and fatigue crack growth behavior in the as-welded and thermally aged conditions. AISI 316L butt weld was subjected to thermal aging in its sensitization range at temperatures 550, 650, and 750 °C for 24 h to study the influence of precipitation tendencies of second phases carbide particles under varying aging conditions on metallurgical, corrosion, passive film and fatigue behavior. Among all welds, aged (750 °C/24 h) AISI 316L weld possessed minimum ferrite content, maximum hardness, and higher segregation of elements such as C and Cr at dendritic regions. For corrosion and passive film characteristics, unaged weld exhibited maximum pitting potential, minimum degree of sensitization (DOS), higher concentrations of Cr, O, Ni, Mo in the passive film, and greater passive film protectiveness. With rise in aging temperature from 550 to 750 °C, deterioration in corrosion performance and passive film protectiveness was noticed. On the contrary, aging at 750 °C for 24 h improved the fatigue crack growth resistance owing to accelerated precipitation of carbides compared to aged (550 °C/24 h, 650 °C/24 h) and unaged AISI 316L welds. From this study, it was inferred, that although thermal aging degraded the corrosion performance and passive film resistance but at the same time it enhanced the fatigue crack growth resistance of AISI 316L weld. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.