Investigation of intergranular corrosion welded joint of austenitic stainless steel by electrochemical methods

Abstract

Sensitization degree of the austenitic stainless steel welded joints was investigated by electrochemical methods: the double loop electrochemical potentiokinetic reactivation (DL EPR) in H2SO4 + KSCN solution and by of the corrosion potentials measurement of the steel in the solution drop of HNO3 + FeCl3 6H2O + HCl. The welded joints, by an X-ray radiographic method on possible presence of the weld defects, were tested. Grain size of the base metal and the welded joints, by applying an optical microscopy were determined. The existence of compatibility between the results for different electrochemical methods is shown. Heat affected zone (HAZ) of the austenitic stainless steel welded joints has shown significant degree of sensitization. The corrosion potentials measurement method is simple, nondestructive method, that gives qualitative informations about degree of the sensitizations of the stainless steel. The double loop electrochemical potentiokinetic method gives quantitative evidence about susceptibility of the stainless steel to intergranular corrosion. This method can be applied with some adaptation in field environments.