Fabrication of a High Chromium Cast Iron/Low Carbon Steel Bimetal: Diffusion Behavior and Bonding Strength

In the present study, a high chromium cast iron (HCCI) alloyed with Mo (16 wt.% Cr-6 wt.% Mo-2.4 wt.% C) with excellent wear resistance was bonded to a low carbon steel (LCS) by surface liquid-phase sintering. The bimetal was also subjected to a quenching + tempering treatment. The diffusion behavior of the atoms between the HCCI and LCS was analyzed. The bonding strength of the bimetal was investigated before and after heat treatment. The results show that the bimetal had a good bonding quality due to the uphill diffusion of C atoms. A diffusion zone with a width of approximately 37 μm and a troostite structure formed on the HCCI side by the interface. With different bonding times, there was no obvious change in the width of the diffusion zone. The shear strength of the bimetal at all holding times was reduced from a high level after heat treatment and decreased with increasing tempering temperature. The impact toughness of the bimetal substantially increased compared with that of the HCCI. After a quenching treatment, the impact toughness of the bimetal decreased, and the microhardness of the diffusion zone improved. As the tempering temperature increased, the microhardness and impact toughness decreased and increased, respectively.