Microstructure and mechanical properties of cemented carbide to steel joints by electron beam welding

Dissimilar materials joints without macroscopic cracks were obtained between cemented carbide and steel by electron beam welding inclined to steel with Ni-based filling layer. The joints were fusion-brazed in shape of "half-nail",and solid metallurgical bonding was obtained at the hard alloy/weld interface and the steel/weld interface. Micro-melting of hard alloy base metal occurred and some WC particles diffused into the weld. Microstructure analysis of the weld revealed that γ(Fe, Ni) solid solution and "herringbone" carbides mainly composed of W₂C and Fe₃W₃C formed in the interface on hard alloy side, and martensite formed in the heat-affected zone of steel. The weld mainly consisted of Fe and Ni,and Ni diffused towards the interface on hard alloy side. The maximum tensile strength of the joint was 560 MPa and the maximum shearing strength was 460 MPa with features of quasi-cleavage fracture.