Study on Corrosion Behavior of HDR Duplex Stainless Steel Welded Joints

Aiming at the actual corrosion problem of HDR duplex stainless steel used in marine seawater system, this paper studies the corrosion behavior of welded joints. The corrosion behavior of welded joints was studied by means of microstructure analysis, potentiodynamic polarization xperiment and double-ring potentiodynamic reactivation experiment, and the influence of welding process parameters on the corrosion resistance of HDR duplex stainless steel welded joints was nvestigated. The results show that: (1) The backing welding current has obvious influence on the microstructure of weld metal of HDR steel. The grains in the lower part of the weld are smaller, the quantity is high. (2) The backing welding current has obvious influence on the microstructure of the heat affected zone of HDR steel welded joint, and heat treatment promotes the transformation from ferrite to austenite in the heat affected zone. (3) The ratio of two phases is closer to 1, and the weld metal has better intergranular corrosion resistance in DL-EPR experiment; When the chromium content is low, the intergranular corrosion resistance of weld metal is poor; With the ncrease of welding gap, the Ra value of weld metal increases gradually, and the intergranular corrosion sensitivity increases gradually.