The Effect of Pre-Hydrogen Charging on Corrosion Behaviour of Superduplex Stainless Steel Welded Joints

Abstract

The paper presents results of research undertaken to determine the influence of hydrogen on passivity and corrosion resistance of 2507 super duplex stainless steel welded joints. Butt welded joints were made with low heat input using flux corded arc welding (FCAW) method. Coupons of 5.0 x 5.0 mm were cut from the welded joints containing weld metal (WM), heat affected zone (HAZ) and parent metal (PM). Hydrogen was introduced into the samples by cathodic current method under galvanostatic condition at room temperature. Corrosion resistance was qualified with the polarization curves registered in synthetic sea water. Electrochemical hydrogen charging affected the native passive layer. The internal hydrogen shifted corrosion potential to the more active direction and cause an increase in corrosion current density. The corrosion sensitivity increases for higher current density applied during hydrogen charging. Weld metal area has been revealed as the most sensitive to corrosion attack.