Corrosion behaviors according to the welding process of superduplex stainless steel welded tubes: Gas tungsten arc welding vs. laser beam welding

The corrosion behaviors of superduplex stainless steel welded tubes in an acidic brine environment were examined by comparing the welds formed by the two welding processes of tungsten inert gas (TIG) welding and laser beam (LB) welding. In contrast to TIG-welds with a larger bead size, higher oxide inclusion, and lower N content, the poor corrosion resistance of as-welded LB-weld sample recovered after post-weld heat treatment (PWHT) by restoring the phase balance and dissolving the deleterious inhomogeneities around the fusion line. The key metallurgical factor controlling the corrosion behavior of LB-welded steel tubes, and underlying corrosion mechanism were also provided.