Tantalum ingot → primary forging → pickling → heat treatment → secondary forging → pickling → heat treatment → tertiary forging → pickling → heat treatment
The specific scheme is as follows:
1. Tantalum ingot: diameter ≥160mm, 160mm≦ diameter ≦300mm; Chemical composition is Ta≥99.99%.
2. Single forging: cold forging, rotary forging method is adopted to forge and press large diameter tantalum ingot, and the forging processing rate is controlled at 25%-40%.
3. Pickling: HCl: HF = 5:2 (volume ratio), pickling time is controlled within 2-5 minutes, this treatment is mainly to remove surface impurities, visible tantalum luster without stains can be seen by naked eye.
4. Heat treatment: the heat treatment temperature is 25%-45% of the melting point of tantalum material, and the holding time is 60min.
5. Secondary forging: the hot forging method, first preheat at 200℃, smear glass powder, smear thickness control in 1-3mm; Then, the target billet was heated to 800℃-1200℃, and the upsetting rate was controlled at 55%-80%. When drawing length, the forging feeding amount L=0.6 ~ 0.8h (h is the height of blank before forging), and the pressing amount Δh=0.12 ~ 0.15h. In order to obtain a more uniform deformation, the feeding positions of each pass compression before and after should be interleaved during drawing length operation. In order to ensure consistent and controllable pressing each time, standard measuring block is used as the cushion block.
6. Pickling: HCl: HF: H2SO4 = 5:3:2 (volume ratio), the pickling time is controlled within 5-10 minutes, the surface impurities are removed, and the tantalum luster without stains can be seen by naked eye.
7. Heat treatment: The heat treatment temperature is 25%-45% of the melting point of tantalum material, and the holding time is 60min.
8. Three forging: hot forging: first preheat 200℃, smear glass powder, smear thickness control in 1-3mm; Then, the target billet was heated to 800℃-1200℃, and the upsetting rate was controlled at 55%-80%. When drawing length, the forging feeding amount L=0.6 ~ 0.8h, (h is the height of blank before forging), and the pressing amount Δh=0.12 ~ 0.15h. In order to obtain a more uniform deformation, the feeding positions of each pass compression before and after should be interleaved during drawing length operation. In order to ensure consistent and controllable pressing each time, standard measuring block is used as the cushion block. Upsetting, the height is adjusted according to different size of the finished product.
9. Pickling: HCl: HF: H2SO4 = 5:3:2 (volume ratio), the pickling time is controlled within 5-10 minutes, the surface impurities are removed, and the tantalum luster without stains can be seen by naked eye.
10. Heat treatment: the heat treatment temperature is 25%~45% of the melting point of tantalum material, and the holding time is 60min.
