Effect of post-weld heat treatment on microstructure evolution and pitting corrosion resistance of electron beam-welded duplex stainless steel

The effects of electron beam welding and subsequent post-weld heat treatment at different temperatures on the microstructure evolution and pitting corrosion resistance of duplex stainless steel were investigated. The as welded joint exhibited poor pitting corrosion resistance, and pitting preferentially occurred at the ferrite grain in the weld. Heat treatment promoted austenite formation, Cr2N dissolution, and eliminated dendritic segregation, consequently improving the corrosion resistance of the welded joint. The optimal solution temperature range was 1050-1110 degrees C. The austenite in the weld was prone to selective corrosion after heat treatment owing to its lower pitting resistance equivalent number.