Accurately positioned welding of diamond grains onto the working face of tool substrate

In some consolidating processes such as brazing, it is difficult for every diamond grain to be fixed in a particular position precisely due to the flow of the molten pool or the movement of the diamond grains. To solve the problem, in our work, pre-bonded diamond grains were firmly and precisely welded onto the working face of tool substrate using resistance spot welding technology with hot pressing function. After resistance spot welding, the welding material pre-wrapped around the diamond grains and the substrate formed a relatively tight metallurgical bond, while the diamond grains maintained their original sharpness. The developed process caused a mean compressive stress of 0.34 GPa from 180 to 600 μm under the exposed surface of the diamond grains welded by resistance spot welding. The short resistance spot welding time and protection of surrounding alloy resulted in the impact-resistance strength of diamond grains welded by resistance welding being only 4.2% lower than that of the pre-bonding process. The center of every diamond grain welded by resistance welding was distributed radially within 3 ± 0.1 mm from the edge of the working faces, while the center of every brazed grain was distributed radially within 3 ± 0.6 mm from the edge of the working faces. The grinding test showed that the anti-wear and grinding property of the diamond grains welded by resistance spot welding was better than that of the brazed diamond grains.