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

摘要

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 (Cr_7C_3). 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 (Fe_3Si) in the clad with 45Fe39Cr6C10Si was taken as the reason for the reduced corrosion resistance observed as compared to those of the other clads.