How to forge titanium round bar
1. The forging of titanium round bar is mainly drawing. The whole forging process can be divided into open forging, intermediate (semi-finished) forging and finished forging. The first heat forging of ingot is called open forging, and the rest is intermediate forging and finished forging.
2. When the ingot is open, the first step is light forging and fast forging. The reduction of each stroke should be small, which is no more than 80 mm for pure titanium round bar and no more than 60 mm for alloy. When the total deformation reaches 20-30% (forging ratio 1.25-1.43), the reduction of each stroke can be increased, which is 80-100 mm for pure titanium and 60-80 mm for alloy. When the deformation is basically completed or the temperature is quite low, the deformation should be gradually reduced to avoid deformation There are cracks.
3. During normal forging drawing, the feeding amount (LO) is generally 0.75 of the hammer head width (b), that is, Lo = 0.75b. For example: for 2000t hydraulic press, B = 400mm, then Lo = 0.75b = 338MM, and the reduction should not be greater than 2 / 3 of the feed, that is ho-h = 2 / 3 lo.
4. In the first heat of finished titanium round bar products (products that can be delivered after rounding), the blank should be chamfered, that is, octagonal or dodecagonal, and the size should be appropriate, not too large or too small.
5. The forging of finished titanium round bar is mainly round breaking. When round breaking, the first pass should be pressed gently to avoid bending. In the second pass, the reduction should be increased, and each bar should be pressed at least three times to ensure the outer diameter tolerance required by the process card, and the waste heat of billet should be used for straightening. If the material temperature is too low, but the bending degree does not meet the requirements, it can be reheated for straightening. The straightening heating temperature is generally 150 ~ 200 ℃ below the phase transformation temperature, and the holding time is determined according to the size of the material. For the bars that need to be annealed, the temperature when they are discharged from the furnace after annealing can be straightened.
6. Requirements for bending: there are no special requirements for the bending of blank after open billet and intermediate forging, and the bending of bar delivered with black skin is not more than 6 mm / m when forging the finished product. For the bar delivered with bare bar, the bending is not more than 3mm / m.
7. After each heat forging, the hot cutting shall be carried out according to the required length of the process card. The hot cutting temperature is shown in Table 5, because if the temperature is too high, it is difficult to cut off and easy to deform, which will affect the blank size. If the temperature is too low, the pressure required is large, and it is not safe. The cutting angle of both ends shall not be greater than 10% of the straight diameter, and there shall be no obvious horseshoe shape. Hot cutting is not adopted for finished bar.
