Effects of silicon content on the microstructure and corrosion behavior of Fe–Cr–C hardfacing alloys

Three Fe-based alloys, namely 55Fe39Cr6C, 49Fe39Cr6C6Si, and 45Fe39Cr6C10Si (wt.%), were fabricated on AISI St52 using a tungsten-inert gas (TIG) heat source. Microstructure, microhardness, and electrochemical corrosion behavior of the TIG clad composite coatings were investigated. It was found that as-deposited coatings consisted of higher volume fractions of carbides (Cr7C3). Potentiodynamic polarization studies in the 3.5 wt.% NaCl solution showed that the corrosion resistance of the substrate was remarkably improved by TIG surface coating (TSC) with 55Fe39Cr6C and 49Fe39Cr6C6Si, while 45Fe39Cr6C10Si had a lower effect on this same property. The formation of silicides (Fe3Si) in the clad with 45Fe39Cr6C10Si was taken as the reason for the reduced corrosion resistance observed as compared to those of the other clads.