Study of intergranular corrosion resistance of overlay by Electroslag cladding with austenitic stainless steel

The welding joints were obtained through surfacing the Cr-Ni stainless steel on Q235 by ESW (electroslag strip cladding) and SAW (submerged arc welding). The influence of these two methods and welding speeds on microstructures and intergranular corrosion resistance of overlays was researched. The microstructures of overlays cladded by ESW and SAW are austenitic combinated with δ-ferrite. With the increasing of welding speed of ESW, the δ-ferrite content of overlays increases from 6.8% to 20.4%; While the δ-ferrite content of SAW surfacing mental is the highest in all samples, reaching 23.6%. EPR (Electrochemical Potentiodynamic Reactivation) test shows that the re-activating rate (Ra) of overlay cladded by ESW with the welding speed v=8m/h is the lowest, just only 3.22%, which indicates the best performance of anti-intergranular corrosion. Changing welding speed or method will rapidly increase Ra, resulting in a decrease of the resistance of intergranular corrosion. The results of 10% oxalic acid electrolytic etching test are the same as EPR.