Experiments and numerical simulations on joint formation and material flow during resistance upset welding of WC-10Co and B318 steel

Abstract

Joints of WC-10Co and B318 steel were obtained using resistance upset welding for the application of carbide-tipped sawblades. Research concerning resistance upset welding of WC-Co and steel is rare, and the joint formation evolution and material flow phenomenon have not been studied. The welding current was the research parameter to study the joint formation evolution and the material flow phenomenon during welding by analysing high-speed photography, numerical simulation results, macro and micro morphologies, mechanical properties, and the fracture morphology of welded joints. The results showed that with an increased heat input, the shear strength of the joint had an initial increasing trend before decreasing. The maximum shear strength under a suitable welding current (850 A) was 678 MPa. The joint formation process as captured with a high-speed camera was consistent with the numerical simulation results, which verifies the model. The simulation results revealed that a larger heat input gave a faster material flow. The thickness of the reaction layer at the centre of the interface was the smallest and increased from the centre to the periphery as related to the material flow. Compared with other welding approaches, resistance upset welding of cemented carbide and steel generates extrudates on the steel side. As the welding current increased, the extrudates shifted from the centre of the interface to the edges.