Influence of filler wires and high velocity oxygen fuel coating on the structural properties of Inconel 600 and Nickel alloy 800 HT dissimilar joints using autogenous cold metal transfer welding

Abstract

The present study shows the effect of filler wire and Thermal Spray (TS) coating on the microstructure and tensile properties of dissimilar joints of Inconel 600 and Nickel alloy 800 HT using Autogenous Cold Metal Transfer (A-CMT) welding by employing ERNiCr-3 and ERNiCrMo-4 filler wires. Cold metal transfer welding was performed on dissimilar metals based on welding current (50–60 A), welding speed (200–300 mm min−1) and arc distance (8–10 mm). Tensile properties studies were performed and resulted that the maximum yield strength of dissimilar weldments sample was 554 MPa. To improve the mechanical properties, a NiCrMo coating was applied on the welded surface and the tensile strength improved to 687 MPa. The failure analysis was performed using Comsol software and observed that all tensile failures were occurred in the heat affected zone which is accordance with the experimental tensile result. Hardness studies revealed that the TSC weld hardness was found to be better than the as-weldments which is acquainted due to the MoC and Mo2C reinforcement effect. The microstructure investigation of weldments and TS Coating samples were conducted in the fusion zone using Scanning Electron Microscopy (SEM), x-ray diffractometry and Transmission Electron Microscopy (TEM). Microstructure studies obviously showed the different faces of nickel carbide (Ni3C) on the weld zone because of employing TS coating process. This study addressed the improvement of tensile and bending strength using suitable TSC.