CHARACTERIZATION OF CORROSION BEHAVIOR OF INCONEL 617 WELDED JOINTS USING CMT-GMAW MULTI-CONTROL WELDING

This work addressed the effect of CMT-GMAW multi-control welding of Inconel 617 alloy with different wire feed rates (8.9, 9.4, and 9.9 m/min) on the microstructure, hardness, and electrochemical properties. The weld joints are composed of columnar dendritic structure with cellular crystals. Electron backscattered diffraction (EBSD) study showed equiaxed dendrite at the center of weld metal with growth direction perpendicular to the fusion boundary. The weldments showed diffraction peaks at 43.53°, 50.12°, and 74.82°, and these peaks mainly represent gamma (g) and gamma prime (g') phases along with the carbide peaks of Ti (C, N), M23C6 and M6C. The Base metal (BM) had a lower hardness (232 ± 10 HV0.2) and lower corrosion rate (0.212 mpy) than the weld joints. The increase in wire feed rate (WFR) results in the decrease of microhardness (267 ± 5 - 251 ± 6 HV0.2) and increase in corrosion rate (1.833-28.140 mpy). The base metal exhibited higher potential (Ecorr) and lower current density (Icorr) than the weld joints. As wire feed rate (WFR) increases, heat input increases; solidification time increases, grain boundaries coarsen, resulting in a lower grain boundary (GB) density, and hence increased carbide precipitation and segregation in weld zone leading to higher stable anodic current density, which caused corrosion resistance to deteriorating. The BM was more corrosion resistant than the weld joints. The metallurgical and physical changes caused by the welding process affect the corrosion resistance of the weld joints. This leads to the weld metal corroding faster than the base metal.