采用Fe-30%Ni中间层电子束焊接硬质合金与钢

YGH-60 cemented carbide and 45 steel were welded by electron beam with the middle layer of Fe-30%Ni. The microstructure, microhardness and fracture mode were analyzed. The results showed that the weldability of YGH-60 cemented carbide and the 45 steel was very poor, the diffusion of Fe/Ni elements and the formation of brittle phase could be controlled with the addition of Ni element. Moreover, internal stress could be relaxed in the welding process due to good plasticity of Ni. In addition, Ni element could alleviate the large thermal stress caused by the linear expansion coefficient and the thermal conductivity of the cemented carbide and steel, and then improved the crack resistance of the joint. Excessive Fe element would weaken the optimization of the Ni. Fe₂W₄C was formed by Fe 53% in the middle layer and WC, which existed on the surface of WC under the effect of electron beam. Banded solid solution mixture was formed at the interface of the cemented carbide/interlayer, which reduced the mechanical properties of the joints. Mechanical properties of the joints were carried out that average tensile strength exceeded 66 MPa. Fracture occurred at the interface between the cemented carbide and the interlayer, and the fracture morphology exhibited quasi-cleavage. Due to the less melting amount of cemented carbide, it was difficult to fuse with the middle layer, so it was difficult to form a joint with good mechanical properties.