Interface Evolution of YG11C/42CrMo Joint Brazed with BCu64MnNi Filler Metal

An erosion often occurs, when brazing cemented carbide with Cu–Mn based filler alloy, therefore, the binder phase erosion and interface evolution are systematically investigated. When heating, the binder phase Co dissolves into the molten filler and the erosion product acquires liquid state. Heavy WC particles successively submerge into the molten filler, while the erosion layer becomes incompact. With increasing brazing temperature, the tensile strength increases to the maximum 589MPa at 970 °C with holding for 300 sec, and then decreases to 431 MPa at 1010 °C. The microscopic fracture morphology analysis reveals that the erosion product possesses poor wettability against WC particles. When long-time heat preservation at 970 °C, a structure gradient layer is locally formed, because the de-bonded WC particles submerge into the liquid filler metal successively, which promotes the thermal stress release and obtaining high-strength joint.