Corrosion resistance of superduplex stainless steel welded joint

The changes of two phases proportion and element composition of superduplex welded joints stainless steels UNS S32750 welded joints by different technics were studied by SEM and EDS,meanwhile the pitting corrosion and intergranular corrosion resistance of welded joints were tested by critical pitting temperature(CPT) and 65% nitric acid solution experiment.The results showed that higher heat input,filling welding wire and nitrogen gas protection could make austenitic phase exist steadily,and higher heat input could make chromium to diffuse so as to reduce intergranular corrosion sensitivity which on the contrary make pitting corrosion worse.The reason is that the ferrite phase dissolves firstly because of the element partition disproportion.