Influence of Microstructural Features on the Mechanical Behavior of Incoloy 825 Welds

This work deals with an investigation on the structure–property relationships of Incoloy 825 weldments. Incoloy 825 was successfully welded using gas tungsten arc welding and different filler wires. Interfacial and weld zone microstructures were characterized by optical microscopy, X-ray diffraction analysis, and scanning electron microscopy equipped with energy dispersive spectroscopy. Micro-hardness, tensile and Charpy impact tests were also conducted for the evaluation of the mechanical properties of the weldments. Ti-rich and Nb-rich phases were identified in the inter-dendritic regions of the weld metals. In the heat-affected zone of the weldments, grain growth and grain boundary thickening were observed. All the weldments displayed the ductile mode of fractures. ERNiCrMo-3 showed higher hardness, better toughness and tensile properties than the other weld metals. In addition, ERNiCrMo-3 indicated a higher impact resistance (112 J) compared to the base metal (94 J). Thus, ERNiCrMo-3 filler wire was recommended for welding alloy 825.