Microstructural characterization and mechanical response of Inconel 600 welded joint

Abstract

In this study, plates of IN600 super alloy were gas metal arc welded with an ERNiCrMo-3 filler wire and the effect of the welding process was evaluated in the as-welded joint in terms of microstructure, mechanical properties and true stress−true strain hardening behavior. The microstructural characterization of the as-welded samples revealed Mo–Nb rich precipitates in the inter-dendritic spaces in the weld metal and significant grain growth in the thermally affected zone. The results indicate that under quasi-static tensile stress, the ultimate strength of the welded joints decreased by 100 MPa as compared to the as-received alloy. The failure of the as-welded samples consistently occurred in a soft zone at the IN600 base metal in a ductile fashion. The tension test stress–strain behavior on both samples was analyzed using Ramberg-Osgood model by means of a two-slope hardening approach and the results indicate that the stress-strain behavior of the base metal and welded joints can be well described for strain values of 0 to 0.1. Characterization of the failure zone by EBSD analysis revealed that fractured as-received IN600 sample exhibit an overall lower residual strain compared to the grains of the fractured welded sample and that near the fracture region the welding process promoted an increment in carbides.