Superduplex stainless steels (SDSS) are alloys widely used in the exploration and production of oil. They are used in marine and offshore components such as heat exchangers, umbilicals, seawater injection lines and various other equipment that require high corrosion resistance with elevated mechanical strength values. These characteristics are due to its fine two-phase microstructure composed of similar proportions of austenite and ferrite and the alloying elements of Cr, Ni, Mo, N and W. However, during welding, and also in the stages of fabrication and pipe assembly, the presence of defects may occur that requires the need for repair procedures to be carried out on the welded joint. This study aims to characterize the microstructure, mechanical properties, nitrogen content and critical pitting temperature (CPT) of a SDSS pipe, UNS S32760, in certain regions of a welded joint, where the GTAW welding process was performed, with the completion of two sequential repair procedures. The results show that there is a decrease in the value of the critical pitting temperature at the root of the weld, though there aren't substantial variations in the mechanical properties analyzed.
Superduplex stainless steels; Welding repair; Mechanical properties; Corrosion resistance
