Joint performance and hierarchical behavior of WC-10Co/B318 steel dissimilar resistance welds with different V-groove depths

Abstract

Resistance welding provides unique advantages over other joining processes in combining a small portion of cemented carbide with a large part of steel for the purpose of applying carbide band saw blades and achieving the effect of cost reduction, material savings, and increased efficiency. Based on previous studies, this research examines how V-groove depth affects the quality of resistance-welded WC-10Co and B318 steel joints in order to improve the service life of carbide band saw blades. The joints' shear force, welding process, macroscopic morphology, microstructure, fracture, microhardness, and toughness are explored to reveal joint performance and hierarchical behavior. The results show that the joint with a V3 groove has a higher and more stable shear force among the three investigated V-groove depths due to the smaller interfacial reaction layer and less WC-10Co loss. High-speed photographic results reflect differences in the location and amount of heat production in the three types of joints, corresponding to the microstructure and fracture morphology. A deeper groove depth results in high utilization of Ni, less welding slag encapsulating the WC-10Co, and reduced cracks. The joint's microstructure and fracture morphology exhibit ellipsoidal and fishbone-like structures, demonstrating a hierarchical behavior between the ellipsoidal and fishbone-like structures. This hierarchical behavior is mainly attributed to the interactions among Ni, W, Co, C, and molten Fe and elemental migration, with the formation mechanism explained by the structural evolution schematic, which has never been mentioned in other studies. Accordingly, the V3 groove provides the optimal groove depth as it delivers the best joint performance by combining. This study provides experimental data and theoretical references for the actual machining of carbide band saw blades.