Effect of brazing temperature and holding time on joint properties of induction brazed WC-Co/carbon steel using Ag-based alloy

Because of insufficient understanding of the strengthening effect of α-Cu (s.s) in WC-Co/interlayer/35CrMo joints, this research focused on revealing the evolution and strengthening effect of α-Cu (s.s) with brazing temperature and holding time. The joints were performed by high-frequency induction brazing using an Ag-based alloy (Ag-16Cu-23Zn-7.5Mn-4.5Ni, wt.%) as the filler metal. Island-like α-Cu solid solution (s.s) phases widely spread in the filler metal and played a role of dispersion strengthening because of the high hardness. Because of the high affinity between Ni, Co and Fe, α-Cu (s.s) layers formed at the interfaces and strengthened them. The joint strength increased with widening α-Cu (s.s) layers. With increasing brazing temperature and holding time, the total area and number of island-like α-Cu (s.s) phases decreased, contributing to weakening the dispersion strengthening effect. The maximum shear strength of brazed joints was 366 MPa when brazing at 770 °C for 30 s.