Effect of a brief post-weld heat treatment on the microstructure evolution and pitting corrosion of laser beam welded UNS S31803 duplex stainless steel

The effect of laser-beam welding and subsequent short-time post-weld heat treatment at different temperatures and holding time on microstructure evolution and pitting corrosion behavior of UNS S31803 duplex stainless steel was investigated. The results showed the as-welded joint displayed impaired pitting corrosion resistance and that pitting preferentially occurred at ferrite grain in the fusion zone. Short-time heat treatment enhanced the pitting corrosion resistance of welded joint. Optimal post-weld heat treatment of 3 min heat treatment at 1080 °C was identified at which the joint restored the pitting corrosion resistance lost during welding process.

► Pitting corrosion is investigated before and after post-weld heat treatment.
► The Cr2N precipitation is studied by SEM, TEM and AFM.
► The best short-time post-weld heat treatment condition is determined.
► The cause of pitting corrosion resistance variation is discussed in detail.