Knowledge related to titanium alloy forging!
Preparation before forging of titanium forgings
Before production, the operator should first check the equipment operation record, and test run to check whether the equipment operates normally. If there is any problem, notify the maintenance worker to deal with it.
Each member of the team should clarify the production tasks of the team, understand the process requirements on the process card, and develop the forging sequence for the team.
Each member prepares the necessary tools for production according to their own responsibilities. Like hanging pliers, molds, throwing tools, punches, knives, calipers, rulers, etc.
For some alloy materials or materials with smaller sizes (small materials with fast temperature drop), tools such as hammers, hammers, punches, and knives should be fully preheated within the temperature range of 150-300 ℃ before forging to ensure forging quality and prevent crack formation.
Forging of bars
The forging of bars mainly involves elongation, and the entire forging process can be divided into blank forging, intermediate (semi-finished) forging, and finished product forging. The hot forging of ingots is called billet forging, while the rest is intermediate forging and finished forging.
When opening the ingot, follow the principle of "one light, two heavy, and three small". When opening the ingot, the first step is to lightly and quickly forge, with a small reduction per stroke. Pure titanium should not exceed 80mm each time, and alloy should not exceed 60mm each time; When the total deformation reaches 20-30% (forging ratio 1.25-1.43), the reduction per stroke can be increased, with pure titanium being 80-100 mm and alloy being 60-80 mm; When the deformation is basically completed or the temperature is relatively low, the deformation amount should be gradually reduced to avoid cracks.
When forging and drawing normally, the feeding amount (Lo) is generally 0.75 of the hammer head width (B), that is, Lo=0.75B. For example, for a 2000t hydraulic press, if B=400 mm, then Lo=0.75B=338 mm, and the reduction amount should not be greater than 2/3 of the feed amount, i.e. ho-h=2/3 Lo. To avoid folding, resulting in the need for polishing, wasting manpower, and affecting the yield. If the process card does not require full hammer forging, it is generally treated as normal forging.
Before the production of finished products (products that can be delivered after being rounded), the blank should be chamfered, that is, octagonal or twelve square, and the size should be appropriate, not too large or too small. If the size is too large, it can easily cause folding and cannot complete the rounding process. If it is too small, it cannot meet the size of the finished product.
The forging of finished bars mainly involves rounding off. When rounding off, the first pass should be lightly pressed to avoid bending. The second pass should increase the amount of reduction, and each bar Z should be pressed three times less to ensure the outer diameter tolerance required by the process card. Additionally, the residual heat of the billet should be used for straightening. If the material temperature is too low but the bending does not meet the requirements, it can be reheated for straightening. The straightening heating temperature is generally 150-200 ℃ below the phase change temperature, and the insulation time is determined based on the size of the material. For bars that need to be annealed, the temperature at which they are discharged after annealing can be used for straightening.
