TLP Bonding of WC-6Co to 1045 Steel Using Multi-Interlayer of Ni/Cu/Sn/Cu/Ni

Transient liquid phase (TLP) bonding of WC-6Co cemented carbide to 1045 steel was performed at 800 °C for different holding times of 10, 20, 30 and 40 minutes using a selected Ni/Cu/Sn/Cu/Ni multi-interlayer. To evaluate the effect of overall thickness of the joints on bonding strength for bonding time of 30 minutes, three different thicknesses of joints (70, 120 and 170 micrometers) were also examined. By increasing the TLP holding time to 30 minutes, due to a rather completing of homogenization of the isothermally formed (Cu) solid solution in joint area, the maximum shear strength of 160 MPa was obtained for the joint with overall thickness of 120 micrometers then by prolonging the holding time to 40 minutes, it decreased slightly as a result of softening effect (coarsening). It was also observed that by decreasing the width of the joint from 170 to 70 micrometers, due to the removing of the bending component of the shear stress, the shear strength of the joints raised from 141 to 173 MPa. It was also observed that by electro deposition of a nickel layer on joining surface of the substrates and TLP formation (Cu)_ss, the formation of cobalt depletion zone, destructive phases like η, and micro cracks caused by residual stresses in joint area can be prevented.