Microstructural Characterization of a Component Manufactured by Hybrid Casting of Two Different Ferrous Alloys

Hybrid casting is a new fabrication concept that can reduce costs and production time of large tools, such as stamping tools for the automotive industry. In this work, we analyzed a hybrid material composed of a high chromium cast iron (HCCI) and a low carbon steel (WCB). SEM analyses indicate that the interface is free of non-metallic inclusions and porosities. The metallurgical bonding between alloys is confirmed by the diffusion of chromium and carbon from HCCI to WCB. Vickers microhardness, EDS and XRD confirmed the presence of M7C3 carbides in the HCCI and at the interface. One set of the samples was submitted to regular quenching in calm air and tempering, while another set was additionally submitted to subzero quenching before tempering. In both cases, a slight reduction of the HCCI hardness and an increase of the interface hardness were observed. The subzero treatment was effective to reduce the amount of retained austenite at the HCCI and limiting its hardness reduction. WCB microstructure and hardness showed no significative change, making it an ideal material to use with HCCI in hybrid casts. The results showed that is possible to produce bimetallic reliable components for industrial applications by means of hybrid casting.