Investigation of microstructure, mechanical, and corrosion behavior of nickel-based alloy 625/duplex stainless steel UNS S32205 dissimilar weldments using ERNiCrMo-3 filler metal

In this study, nickel-based alloy 625 and duplex stainless steel (DSS) UNS S32205 (2205) dissimilar pairs were welded with metal inert gas (MIG) welding process. Weld metal, obtained with the utilization of ERNiCrMo-3 filler wire, was subjected to mechanical, microstructural, and corrosion investigations. V-notch impact tests and micro hardness measurements were realized on dissimilar weld metal. Microstructural changes in weld metal, fusion line, and heat-affected zone were examined using optical, scanning (SEM), and transmission electron microscopes (TEM) with energy-dispersive spectrometry (EDS). Phase precipitations rich of Nb and Mo were detected among dendritic austenite arms in the weld metal. It was observed that ERNiCrMo-3 filler metal had sufficient toughness because of high nickel content. Corrosion tests revealed that weld metal face pass is the least corrosion-resistant zone in weld metal unlike weld root. This is mainly because more intense intermetallics formed in weld metal face compared with the middle of the weld and the root.