Microstructure and corrosion resistance of dissimilar welded joints

This paper investigates dissimilar weldments between duplex stainless steel and carbon steel in atmospheric corrosive environments. The duplex stainless steel grade 1.4062 was welded to the carbon steel grades S355J2/P460NL2 by means of Gas Metal Arc Welding (GMAW). The fabricated specimens were subjected to 5 months exposure tests under 4 different corrosive atmospheric environments, distributed across 3 different countries: Belgium, England and Portugal. A total of 28 samples were designed, fabricated and sand blasted, in order to satisfy the surface requirements of (ISO 8501-1, 2007). Exposure racks were assembled and exposed to the weather conditions at each test location. The samples were placed 74 cm above the ground to prevent rain splashes. The environmental parameters influencing the corrosion of dissimilar welds were monitored on a continuous basis and were correlated to the respective corrosion rates. Finally, prelaminar guidance is given on the necessary coating protection for such weldments in the context of girder bridges.