Pre-bonding and resistance welding process of CBN grits with Cu-Sn-Ti alloy

CBN grits were pre-bonded using Cu-Sn-Ti alloy and then they were welded on the substrate by resistance welding, which was a preliminary exploration for the precise fixation of CBN grits on CBN tools with orderly arranged grits and for the replacing of damaged grits of used CBN tools. Thermal analysis of Cu-Sn-Ti alloy was completed by differential scanning calorimetry. Scanning electron microscope was used to observe the micromorphology of the grits pre-bonded and those welded by resistance welding. Raman spectrometer was used to analyze their stress. The grinding performance of CBN grits welded by resistance welding was studied by grinding test. CBN and Cu-Sn-Ti alloy could combine chemically at 950 ℃ for 120 s. After resistance welding, the pre-bonded layer was fused with the pre-melted coating of the matrix. No defects such as cracks, pores and non-fusion were found in the weld, and CBN grits was still angular. At 600 μm from the surface, the compressive stress of brazed CBN grit was 0.43 GPa, and that of CBN grit welded by resistance welding was 0.69 GPa. The larger compressive stress made the holding force of Cu-Sn-Ti alloy towards CBN grits welded by resistance welding stronger. The grinding tests indicated that the stability and the grinding efficiency of CBN grits welded by resistance welding were better than that of brazed CBN.Highlights: The research could overcome the defect that the grits were easy to move when they were welded by other methods, and it had the special significance for manufacturing and repairing of CBN tools.