Resistance welding of large-size CBN grits

Abstract

ABSTRACT Large-size CBN grits were welded using Cu-Sn-Ti alloy on a steel substrate with precoated Cu-Sn-Ti layer by resistance welding, which served to solve the problem of damage of CBN grits of brazed large-size CBN tools used in high-efficiency heavy-load processing. In the presintering at 950°C for 120 s, the presintered CBN grits were angular and free of thermal damage. The instantaneous contact resistance between the upper electrode and a presintered grit was very high in the initial stage of resistance welding. Therefore, the contact part of presintered layer of presintered grit melted quickly and spattered slightly, causing the CBN grit to produce certain exposure. Cohesive and high-quality welding joint was formed between the CBN grit and precoated layer on substrate, and the CBN grit welded by resistance welding maintained sharp edges and corners. The maximum compressive stress of CBN grit welded by furnace brazing is 0.62 GPa, and that of CBN grit welded by resistance welding after sharpening is 1.03 GPa. Grinding testing suggests that the grinding performance of CBN grits welded by resistance welding is better than that of CBN grits welded by furnace brazing.