Vacuum brazing of YT05 cemented carbide and 40 steel is often used in cutting tool welding. For example, carbide hobbing cutter is a kind of gear hobbing cutter that is widely used in gear production. It can not only process various gears, but also use scraping processing instead of grinding when processing hard-toothed gears. This gear hobbing cutter is welded by YT05 cemented carbide and 40Cr medium carbon quenched and tempered steel by vacuum brazing process.

First, the material of the hobbing cutter

The material of the cutter body is 40Cr steel, and the material of the blade is YT05 carbide.

Second, the filling material

①The brazing material is made of pure copper BCu (Cu99.95%) with a thickness of 0.2mm, the melting temperature is 1083℃, and the brazing temperature is 1100~1150℃.

②The flux, the grade of flux is Y11, the main component is borax, and the melting temperature is 800~1150℃. Brazing flux QJ201 can also be used, the chemical composition is: boric acid 80%, borax 14.5%, calcium fluoride 5.5%; brazing temperature is about 850 ~ 1150 ℃.

Three, brazing operation points

①Cut the needle material according to the tooth shape and place it between the cutter body and the blade. The blade is fixed on the cutter body with a fixture, and the contact part between the fixture and the weldment should be coated with injection, and then put into the vacuum furnace.

②Evacuate the furnace to 5×102Pa in the cold state, then heat the furnace temperature to 1000℃ at a speed of 450℃/h, and fill the furnace with high-purity argon gas to ensure that the pressure in the furnace is 2~3Pa, stable and stable 30~40min to make the temperature inside and outside the knife uniform.

3. Heat the furnace temperature to 1120 °C at a rate of 250 °C/h, keep the temperature for 15 minutes, and then cool the furnace temperature to below 900 °C with the pressure in the furnace; fill the furnace with high-purity argon again to raise the furnace pressure to 4×10Pa

④When the furnace temperature is cooled to below 400℃, increase the filling amount of argon gas to make the pressure in the furnace rise to 8×10Pa, and then start the fan to stir the argon gas. When the furnace temperature is cooled to below 65℃, the workpiece is released from the furnace.

⑤ After the hobbing cutter (including the fixture) is released, it is strictly forbidden to collide, and it should be cooled naturally in the air. At this time, the ambient temperature of the workshop should not be lower than zero.

⑥ After the cutter body and the blade are completely cooled and shrunk, slowly remove the Gao fixture so that the fixture and the hobbing cutter are not damaged, and then clean the fully brazed hobbing cutter to complete the welding.