Effect of carbon content on microstructure and corrosion behavior of hypereutectic Fe–Cr–C claddings

The aim of this study was to examine the influence of carbon content on the microstructures and corrosion characteristics. The results showed that the hypereutectic microstructure comprised primary (Cr,Fe)7C3 carbides and the eutectic colonies [γ-Fe + (Cr,Fe)7C3]. The amounts of primary (Cr,Fe)7C3 carbides increased from 33.81 to 86.14% when carbon content increased from 3.73 to 4.85 wt%. The corrosion resistance of the hypereutectic alloy with 4.85 wt% C was about 20 times higher than that with 3.73 wt% C. The galvanic corrosion occurred in all claddings due to difference of corrosion potential between primary carbide and austenite. The dense distribution of primary carbides could retard the austenitic matrix from selective corrosion. The austenite dissolved the Fe2+ ions and formed a Cr2O3 film under 3.5% NaCl aqueous solution.