Cladding high chromium cast irons on low carbon steel: microstructure and mechanical properties

Abstract

In the present work, high chromium cast irons (HCCIs) with different high carbon ferro-chrome (HCFC) content were cladded on a low carbon steel (LCS). The microstructure and mechanical properties of the bimetals were characterized. The results show that the microstructure of the HCCIs/LCS bimetals is compact, and no defects such as shrinkages and cracks are observed. The volume fraction of carbides increased with the increase of HCFC content. The carbide types of HCCIs are mainly consisting of Cr-rich M7C3 and M23C6, M3C and Mo-rich M2C. The matrix is consisting of martensite near the edges of the carbides and pearlite inside the grains. The hardness and wear resistance of the HCCIs increased with the increasing HCFC content. The HCCIs/LCS bimetals formed good metallurgical bonding, the interfaces are clear and complete. The diffusion of C atoms occurs on the interfaces of the bimetals, and the diffusion direction is from the HCCIs to the LCS, pearlite zones is formed on the LCS side by the interfaces. The thickness of pearlite zones decreased with the increase of HCFC content. Compared with the HCCIs, the HCCIs/LCS bimetals have greatly improved impact toughness, and the impact toughness decreased with the increase of HCFC content.