Characteristics of Bimetallic Castings with Varying Thickness of Liquid High Carbon Grey Cast Iron and Solid High Chromium Stainless Steel 304 Produced by Green Sand Mold Casting

Abstract This study investigates the behaviour of high-chromium stainless steel 304/high-carbon grey cast iron (HCSS 304/HCGCI) bimetallic metal matrix composite alloys (MMCAs) produced via green sand mold casting. The work focuses on the interaction between the molten HCGCI layer and the solid HCSS 304 functional layer during solidification. Elevated pouring temperature promoted effective metallurgical bonding by enabling substantial heat transfer from the liquid HCGCI to the solid HCSS 304 plate. During the uphill casting process, carbon and silicon diffused toward the steel, while chromium migrated from the HCSS 304 into the HCGCI. Ultrasonic non-destructive testing and destructive characterization confirmed the formation of a permanent diffusional bond at the bimetal interface. The interface was observed to be free of defects and exhibited a well-developed dual-phase microstructure comprising α-ferrite, γ-austenite, and minor martensite/carbide constituents. Post-solidification mechanical and microstructural analyses revealed that tensile strength, ductility, hardness, and impact toughness decreased with increasing HCGCI layer thickness. Overall, the findings demonstrate that HCGCI layer thickness significantly influences the mechanical performance and interfacial integrity of HCSS 304/HCGCI bimetallic systems, providing important guidance for optimizing bimetal casting processes.