Effects of Welding Processes on Microstructure and Corrosion Resistance of Weld Metal of Corrosion Resistant Ship Plate Steel DH36

Corrosion resistant ship plate steels DH36 were welded by using submerged-arc welding, flux cored wire CO2 gas shielded welding and shielded metal arc welding processes, and then corrosion experiments were carried out in the simulated environment around bottom plates of cargo oil tanks, the effects of welding processes on microstructure and corrosion resistance of weld metals were studied. The results show that under three welding processes, microstructure of the weld metals consisted predominantly of acicular ferrite, ferrite side-plate and proeutectoid ferrite. Compared with shielded metal arc welding and gas shielded welding, the weld metal prepared by submerged-arc welding had the best corrosion resistance, this due to the decrease of proeutectoid ferrite caused by higher heat input. Under three welding processes, the size and distribution of inclusion in weld metal were similar, and there was no obvious difference in the effects of inclusion on corrosion property of weld metal.