Vacuum brazing process of YT05 cemented carbide and 40Cr steel

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Vacuum brazing of YT05 cemented carbide and 40 steel is often used in cutting tool welding. For example, carbide gear hob is a kind of gear hob which is widely used in gear production. It can not only process all kinds of gears, but also use scraping process instead of grinding process when machining hard gear. The hobbing cutter is made of  YT05 cemented carbide and 40Cr medium carbon quenched and tempered steel by vacuum brazing process.

1. material of gear hob
The blade body is made of 40Cr steel and the blade material is YT05 hard alloy.

2. Filling materials
① for brazing filler metal, BCU (cu99.95%) with thickness of 0.2mm, melting temperature of 1083 ℃ and brazing temperature of 1100-1150 ℃ are selected.

② for flux, the brand of flux is Y11, the main component is borax, and the melting temperature is 800 ~ 1150 ℃. Brazing agent qj201 can also be selected. The chemical composition is: boric acid 80%, borax 14.5%, calcium fluoride 5.5%; brazing temperature is about 850-1150 ℃.

3. key points of brazing operation
① 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 clamp. The contact part between the clamp and the weldment shall be coated with injection agent and then put into the vacuum furnace.

② vacuumize the furnace to 5 × 102pa in cold state, then heat the furnace temperature to 1000 ℃ at 450 ℃ / h, and fill the furnace with high-purity argon to ensure that the pressure in the furnace is 2-3pa, stable for 30-40min, and uniform temperature inside and outside the knife body.

③ heat the furnace temperature to 1120 ℃ at the speed of 250 ℃ / h, keep it warm for 15min, and then cool the furnace temperature to below 900 ℃ with the furnace pressure; fill the furnace with high-purity argon again, and make the furnace pressure rise to 4 × 10Pa.

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

⑤ it is strictly forbidden to collide after the gear hob (including fixture) is put out of the furnace, and it is cooled naturally in the air. At this time, the ambient temperature of the workshop shall not be lower than zero.

⑥ after the cutter body and blade are completely cooled and shrunk, slowly remove the high clamp to prevent the clamp and gear hob from being damaged, then clean the fully brazed gear hob and complete the welding.

Learn More: Vacuum Brazing Furnace