Micro-texture and corrosion behavior of dissimilar joints of UNS S32750 stainless steel/UNS N08825 Ni-based superalloy

The aim of this research was to study the effect of the welding current mode on the microtexture and corrosion behavior of UNS S32750 stainless steel/UNS N08825 Ni-based superalloy welds. The weldments were fabricated using pulsed current (PC) and continuous current (CC) gas tungsten arc welding. The electron backscatter diffraction analysis was used to evaluate the microtexture and boundaries characteristics of the weldments. Corrosion behavior of the weld metals was also investigated using the electrochemical impedance spectroscopy. The obtained results revealed that use of the CC mode resulted in the formation of some texture components in the weld metal; however, the preferential orientations of the weld metals' grains were not detected in the weld metal by employing the PC mode. Examination of the microtexture components formed in the heat-affected zones also indicated that unlike the CC mode, using the PC mode had a slight effect on the initial texture of the base metal. The results of the corrosion tests also demonstrated that employing the PC mode for the weld metal led to a higher corrosion resistance, as compared to the CC weld metal, because of having a random grain orientation distribution.