Monitoring the evolution of resistance-welded WC-10Co/B318 steel joint based on welding time

Abstract

In this study, the authors investigate the resistance welding of WC-10Co pellets and B318 steel for use in the blade of a bimetallic band saw. We used the welding time as the basis to identify the mechanism of evolution of the welded joint by analyzing the welding process as well as the dynamic resistance, depth of penetration, distributions of the temperature and stress fields, macromorphology, microstructural transformation, and mechanical properties of the joint. The results showed that the deformation of the joint and the distribution of the temperature field obtained by numerical simulations were consistent with those captured by a high-speed camera, where this verifies the reliability of the model used for the simulation. The deformation in B318 steel was much greater than that in WC-10Co. The process of evolution of the joint was as follows: The resistance-induced heat that was generated melted a small amount of the Ni layer and the B318 steel at the center of their interface. A transition layer was then formed among WC-10Co, the Ni layer, and the B318 steel. Following this, the transition layer at the center was melted and extruded, where the WC-10Co and B318 steel came into direct contact and a metallurgical reaction occurred between them, while the edges of B318 steel and WC-10Co began to contact. The reactants at the center of the interface were then extruded and metallurgical bonding slowly began along the edges. Finally, the Ni layer disappeared, the steel groove was fully combined with WC-10Co, and some of the reactants that had not been discharged in time solidified at the interface to form a reaction layer.