Characterization of Co Cr alloy cladded over SS316L by cold metal arc transfer process and its parameters optimization

Abstract

In this work, the cladding was done on the SS316L alloy through the Cold metal are transfer process (CMT) process with the use of Stellite-6 filler wire. Cladding was done with current, Voltage, torch angle and travel speed as input parameters. 31 experiments were done at different cladding conditions as per central composite design. Optimization of the cladding process parameter is done with MCDM techniques such as Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), Grey relation analysis (GRA) and complex proportional assessment (COPRAS). Quality of the clad was analysed by measuring depth of penetration, weld area, hardness of the clad surface, corrosion rate and clad interface thickness. The cladding specimens were characterized by Macro-Structural study and Micro- Structural study, Vickers microhardness evaluation, and Corrosion resistance analysis (Potentiodynamic polarization test). An Optical Microscope, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and X-Ray Diffraction (XRD) were used to predict the structural characterizations, presence and the distributions of the elements. The results showed the effectiveness of cladding performed on the metal. Higher current and welding speed showed appreciable hardness at the interface and cladding regions. Macrographs showed the weld bead and molten zones and their influence by the high voltage and current. The thickness of the interface was noted a maximum of 190 microns for 160 Amps welding current. The EDS spectra showed that Fe. Cr and Co were the major elements in the clad and interface regions. The Co-rich phase and the low content of element O are found in the low corroded regions on the specimen. In TOPSIS optimization results showed that the 2nd experiment had the 1st rank and the 19th experiment was in the last rank. Higher current and low welding speed yielded good results and a low corrosion rate of 0.004582 mm/yr. EDS study showed the presence of Cr and Co elements in the cladding region with maximum.