Effect of magnetic field applied during gas metal arc welding on the resistance to localised corrosion of the heat affected zone in AISI 304 stainless steel

Resistance to localised corrosion at the heat affected zone (HAZ) of AISI 304 stainless steel gas metal arc welded (GMAW) in presence of magnetic fields of different intensity was studied. Samples of HAZ, 8 mm away from the weld centre, were subjected to electrochemical potentiokinetic reactivation to assess the degree of sensitisation (DOS). The application of magnetic field during welding induced lower DOS and better resistance to pitting corrosion in 3.5% NaCl solution than samples welded without it. Experimental findings suggest that magnetic fields enable Cr redistribution in the austenitic base metal during the welding thermal cycle reducing Cr depletion.

► Low intensity magnetic fields applied during GMA welding of 304 stainless steel improved the resistance to localized corrosion of the HAZ.
► Magnetic fields could enhance Cr redistribution in the austenite during the welding thermal cycle.
► Chromium carbides precipitation and growth of pre-existent carbides decreased with the applied magnetic field intensity.
► Redistribution of Cr provides a more continuous and corrosion resistant passive film in the HAZ.