Friction resistance and bonding strength of high vanadium alloy steel/low carbon steel bimetal after heat treatments

The bimetals with high strength and toughness are expected to replace traditional single materials in the wear resistance field. In the present study, a high vanadium alloy steel (HVAS) was cladding on the low carbon steel (LCS), and the microstructure and mechanical properties of the HVAS/LCS bimetal before and after heat treatments were investigated. The Microstructure of the HVAS is Mo-rich and V-rich eutectic carbides distributed in the pearlite matrix. After quenched, the pearlites transformed to martensites that with amount of tiny secondary carbides. The hardened martensites transformed to tempered martensites after the tempering treatments. The hardness of the HVAS has been improved after heat treatments by martensitic transformation, the QT500 sample have the maximum hardness of 61 HRC, and shows good friction resistance. The HVAS and the LCS achieved metallurgical bonding, and shows a good bonding interface situation with no defects or unbonded regions. An uphill diffusion phenomenon was observed, C atoms diffused from the LCS to the HVAS forming a ferrite band and a pearlite diffusion zone. The HVAS/LCS bimetal has good bonding strength, the tensile strength of the interface exceeds 397 MPa. The bonding strength decreased after heat treatments, and decreased with the increasing tempering temperature.