Enhancement of surface properties of austenitic stainless steel by nickel based alloy cladding developed using microwave energy technique

Abstract

In the present work, microwave cladding was carried out as a processing method for enhancement of surface properties of Chromium-austenitic stainless-steel (SS-321). Cladding of Nickel based alloy powder of approximately 0.2 mm thickness was developed on SS-321 substrate. Microstructural characterization was done on the developed clad cross sections using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Spectroscope (EDS) and X-Ray Diffraction (XRD) analysis. It revealed good metallurgical bonding of clad layer and substrate by inter diffusion of the constituent elements. From microhardness testing, it was found average microhardness of the clad region as 458 HV and 234 HV in substrate region. Sliding wear test revealed significant wear resistance of clad surfaces compared to unclad surfaces. From cyclic oxidation test, it was observed that the oxide growth in clad samples was less and stable compared to unclad surfaces by thermogravimetric studies. Cladding of substrate surfaces lead to formation of a compound containing chromium, cobalt and silicon due to which formation of transient Ni oxides was inhibited and protective Cr, Co and Si oxides were formed. These oxides avoided diffusion of oxygen into inner layers of clad region and keeping it away from deterioration due to oxidation at 750 °C.