Microstructure evolution and impact toughness of sandwich structured composite prepared by centrifugal casting and hot rolling process

A sandwich structured composite containing a hypereutectic high chromium cast iron (HCCI) core and low carbon steel (LCS) claddings was successfully fabricated by centrifugal casting and hot rolling process, and then a series of heat treatments were employed to optimise the performance of the composites. The evolution of microstructures and microhardness of as cast, hot rolled and heat treated specimens were investigated. The results showed that the interfaces combined well with a good metallurgical bonding before hot rolling. Etuectic carbides are crushed, refined obviously and become more isolated. There is not obvious break between primary carbides. The hardness of hot rolled HCCI is 62 HRC, which is higher than that of as cast HCCI (56 HRC) due to the broken and diffusely distributed carbides. The hardness of hot rolled HCCI can reach up to 69 HRC or above after air quenching. The average impact toughness of LCS/HCCI composite could reach up to 10.1 J cm(-2), which was almost three times that of the as cast sample. Glide lamellas were observed among the interface due to the stagger of LCS and HCCI.