TC4 titanium alloy is one of the most widely used tita […]
TC4 titanium alloy is one of the most widely used titanium alloys. It has high strength and good corrosion resistance, but it is difficult to see seamless titanium tubes made of TC4 in the seamless titanium tube market at home and abroad.
The TC4 titanium material is mainly made of plates, and the TC4 titanium pipes on the market are mainly high-strength thick-walled pipes produced by hot extrusion or oblique piercing. The warm rolling process needs to be improved on the traditional rolls, that is, on the pipe rolling mill. Install induction heating device, this kind of processing equipment has complicated structure, complicated process and high production cost. The main reason for this current situation is the high strength of TC4 titanium alloy and the difficulty of cold rolling. In order to solve the key technology of TC4 seamless tube cold-rolling forming, a series of researches were carried out jointly by schools and enterprises. For example, the direct cold-rolling forming process is used to produce high-strength titanium alloy pipes, which not only greatly reduces production costs, but also meets the requirements for high-performance titanium alloy applications.
The billeting method with different deformations is adopted, and the tube blank is rolled into a tube with a total deformation of 70% after two passes and three passes. Carry out 800℃×1h vacuum annealing between passes. The cooling method is furnace cooling to 500℃ and then air cooling to room temperature to observe the changes in structure and properties. Concluded:
In the case of small deformation billeting, the wall thickness deviation is small, and the surface roughness is gradually reduced; for large deformation billeting, the wall thickness deviation is large, which will affect the wall thickness deviation of the pipes obtained by subsequent passes.
In the case of the same total deformation, the more rolling passes, the greater the elongation and hardness of the pipe, and the higher the strength. Good overall performance.
When rolling with large deformation, the flow of material is strip-shaped, and when rolling with small deformation, the flow of material is bundled. Under the condition that the heat treatment conditions between passes are the same as the subsequent rolling process, the tube with large deformation is billeted The tissue distortion is more serious.
Small deformation billet has little effect on the anisotropy of the pipe; there are certain fluctuations in the anisotropy of the mechanical properties in multi-pass rolling.