Cold rolling TC4 titanium alloy tube technology!
TC4 titanium pipes on the market are mainly high-strength thick wall pipes produced by hot extrusion or oblique piercing. This warm rolling process needs to improve the traditional roll, that is, install induction heating device on the pipe rolling machine. This processing equipment has complex structure, complicated process and high production cost. The main reason for this situation is the high strength of TC4 titanium alloy and the difficulty of cold rolling forming. In order to solve the key technology of TC4 seamless tube cold rolling forming, titanium tube manufacturers have jointly carried out a series of research. If the direct cold rolling forming process is used to produce high-strength titanium alloy pipes, not only the production cost is greatly reduced, but also the requirements for high-performance applications of titanium alloys can be met.
The tube blank is rolled to 70% of the total deformation through two passes and three passes of rolling respectively with different deformation. 800 ℃ between passes × 1h vacuum annealing, the cooling method is furnace cooling to 500 ℃, then air cooling to room temperature, and observe the changes of its structure and properties. The conclusion is:
In the case of small deformation, the wall thickness deviation is small and the surface roughness is gradually reduced; The wall thickness deviation will be large due to the large amount of deformation of the billet, which will affect the wall thickness deviation of the tubes obtained in the subsequent passes of rolling.
With the same total deformation, the more rolling passes, the greater the elongation, hardness and strength of the pipe. Good overall performance.
When rolling with large deformation, the material flow is strip like, while when rolling with small deformation, the material flow is bundle like. When the heat treatment conditions between passes and the subsequent rolling process are the same, the microstructure distortion of the tube produced by large deformation is more serious.
The effect of small deformation on the anisotropy of tube is small; The anisotropy of mechanical properties in multi pass rolling has a certain fluctuation.