Corrosion behavior of hydrogen charged super duplex stainless steel welded joints

The electrochemical behavior of the weld metal, heat-affected zone (HAZ), and base material of super duplex stainless steel (SDSS) welded joints, made with the application of flux-cored arc welding (FCAW) and submerged arc welding (SAW), were investigated with the use of metallographic examinations (optical microscopy and scanning electron microscopy), potentiodynamic polarization measurements and total hydrogen content determination in the initial state and after hydrogen charging. The obtained results revealed that the effect of hydrogen depended on the microstructure and type of the region of a welded joint. The highest amount of hydrogen penetrated the welded joint charged at 1 mA cm⁻². It was observed in case of the FCAW-welded joint, made with lower heat input. The electrochemical measurements showed that the base material was the most corrosion resistant part of the welded joint while the hydrogen charging strongly changed pitting and general corrosion susceptibility of HAZ and weld metal of both welded joints.