Influence of heat treatment on microstructure and mechanical properties of Inconel-625 clad deposited on mild steel

Abstract

The present work investigates on the microstructure and mechanical properties of Inconel-625 clads deposited through tungsten inert gas on mild steel (MS). The microstructure of the deposited clads reveals perfect metallurgical bonding with the substrate. The deposits are dense with almost negligible porosity. To enhance the mechanical properties, Inconel-625 clads are subjected to three different post heat treatments for 4 h. Compared to the as-deposited clad, the microstructure at 650°C heat treated specimens reveals no dissolution of the Laves phase. However, the 850°C and 950°C heat treated samples exhibit partial dissolution and complete dissolution of the Laves phase in the fusion zone, respectively. The 850°C heat treated clads exhibit higher micro hardness compared to the other clads (as-deposited, 650°C and 950°C heat treated clads). This is attributed to the precipitation of γ'' strengthening phases due to availability of more Nb in the fusion zone micro structure.