Vacuum Brazing Process of YT05 Hard Alloy and 40Cr Steel

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Vacuum brazing of YT05 hard alloy and 40 steel is often used in cutting tool welding. For example, hard alloy gear 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 replace the gear grinding process with scraping when processing hard-tooth surface gears. This kind of gear hobbing cutter is made of YT05 hard alloy and 40Cr medium carbon quenched and tempered steel welded by vacuum brazing process.

1.  Material of Hobbing Cutter

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

2. The Filling Material

The brazing filler metal is a pure copper sheet BCu (Cu99.95%) with a thickness of 0.2mm, the melting temperature is 1083°C, and the brazing temperature is 1100~1150°C.

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

3. The Main Points of Brazing Operation

Cut the needle material according to the tooth shape, and clamp it between the knife body and the blade. Fix the blade on the knife body with a jig. The contact part of the jig and the weldment should be coated with injection, and then put into the vacuum furnace.

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

Heat the furnace temperature to 1120°C at a rate of 250°C/h, keep it 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 increase the pressure in the furnace to 4×10Pa.

When the furnace temperature is cooled to below 400℃, increase the argon filling amount to increase the pressure in the furnace 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 out of the furnace.

The hobbing cutter (including the fixture) is strictly prohibited to collide after it is out of the furnace, and it is naturally cooled in the air. At this time, the ambient temperature of the workshop should not be lower than zero.

After the cutter body and the blade are completely cooled and contracted, slowly dismantle the jig so that the jig and the hobbing knife are not damaged, and then clean the fully brazed hobbing knife to complete the welding.