Effect of carbon content on microstructural characteristics of the hypereutectic Fe–Cr–C claddings

The hypereutectic Fe–Cr–C claddings with different C contents were deposited on ASTM A36 steel substrates by flux cored arc welding (FCAW) to investigate that the effect of C content on microstructural characteristics. The results showed that the microstructure of hypereutectic Fe–Cr–C claddings consisted of primary proeutectic (Cr,Fe)7C3 and the austenite plus (Cr,Fe)7C3 eutectic. Proeutectic carbides undergone to several microstructural changes in response to higher carbon content in the cladding. The morphologies of proeutectic (Cr,Fe)7C3 carbides changed from blade-like to rod-like with hexagonal cross section. The amounts of proeutectic (Cr,Fe)7C3 carbides increased with increase of the C contents. The nucleation sites of proeutectic (Cr,Fe)7C3 carbides increased under high undercooling condition. Hence, the latent heat of solidification can be released by formed proeutectic (Cr,Fe)7C3 carbides and then the growth of proeutectic (Cr,Fe)7C3 carbides were suppressed. Consequently, it showed a maximum hardness value (about HRC 62) when the amount of proeutectic (Cr,Fe)7C3 carbides exceeded 86%.