Microstructure, Mechanical Properties, and Corrosion Behavior of Co-Based Stellite 6 Multilayer Overlays Deposited on ASTM A36 Steel by Gas Metal Arc Welding Process

Hardfacing is an effective method for restoring the damaged part. Herein, cobalt-based superalloy Stellite-6 is deposited on A36 substrate using gas metal arc welding process. The mechanical properties, microstructure, and corrosion behavior of Stellite-6 overlays on A36 substrate are examined. Defect-free hard overlays are obtained, and a dilution ratio of 19.9% is achieved with weaving technique. X-ray diffraction analysis reveals the presence of M7C3, M23C6, M6C, and martensite in the Stellite-6 hard overlays. The microstructure of the deposit contains martensite, carbides, and interdendritic precipitates while the mean hardness is 471 HV0.5. Tensile testing with specimens extracted on the longitudinal (LD) and transverse (TD) orientation of the stellite-6 deposit shows a strength above 950 MPa along with the brittle nature of fracture. Grain growth is epitaxial and shows dendritic morphologies. The higher fraction of high-angle grain boundaries improves the tensile strength of the deposit and interface region. The localized corrosion behavior of stellite-6 hard overlays is found to be excellent, and the corrosion analysis exhibits a corrosion rate of 0.10 mils per year (mpy). The outcomes of the study highlight the feasibility of Stellite-6 hard overlays for extending the service life of A36 steel in chloride environments.