Microstructure and properties of WC–Co/3Cr13 joints brazed using Ni electroplated interlayer

The brazed joints of WC–Co cemented carbide and 3Cr13 stainless steel using Ni electroplated on Cu–Zn alloy as interlayer were investigated. The shear strength of the WC–Co/interlayer/3Cr13 joints increased firstly and then decreased with the increase of brazing temperature or brazing time. The maximum shear strength value of the brazed joints was 154 MPa at 1100 °C for 10 min. The characterizations of the WC–Co/interlayer/3Cr13 joints were studied by SEM, EDS and XRD. The results showed that the brazed joints fractured in the bulk WC–Co substrates near the interlayer. The added Ni promoted the formation of interdiffusion zone, which possessed positive effects on the bond strength of the WC–Co/interlayer/3Cr13 joints. Austenite solid solution was formed in the WC–Co/interlayer/3Cr13 joint, and the majority of austenite solid solution presented as columnar crystal. The number of austenite crystals on the WC–Co/interlayer interface was tremendously more than that on the interlayer/3Cr13 interface.

► WC–Co and 3Cr13 were successfully bonded by vacuum brazing using Ni electroplated interlayer. ► Fracture of the brazed joints occurred in the bulk WC–Co substrates. ► Ni promoted the formation of interdiffusion zone and improved the strength of joints. ► The austenite solid solution was formed in the WC–Co/interlayer/3Cr13 joints. ► The majority of austenite solid solution presented as columnar crystal.