TC4 titanium alloy is one of the most widely used titanium alloy, its high strength, good corrosion resistance, but at present domestic and foreign seamless titanium tube market is difficult to see TC4 seamless titanium tube material.

TC4 titanium material is mainly plate, and TC4 titanium pipe in the market is mainly high strength thick wall pipe produced by hot extrusion or oblique perforation, etc. The warm rolling process needs to improve the traditional roll, that is, install induction heating device on the pipe mill. This kind of processing equipment has complex structure, complicated process and high production cost. The main reason for the present 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, a series of researches have been carried out jointly by the university and enterprise. If the direct cold rolling process is used to produce high strength titanium alloy pipe, it can not only greatly reduce the production cost, but also meet the requirements of high performance applications of titanium alloy.

The billets were rolled into the pipes with a total deformation of 70% by two passes and three passes respectively. Vacuum annealing was conducted at 800℃×1h between passes. The cooling method was that the furnace was cooled to 500℃ and then the air cooled to room temperature. The changes of microstructure and properties were observed. The conclusion is that:

Under the condition of small deformation, the wall thickness deviation is small and the surface roughness is gradually reduced. Large deformation of billet and large wall thickness deviation will affect the wall thickness deviation of the tube obtained by subsequent passes of rolling.

When the total deformation is the same, the more rolling passes, the greater the elongation and hardness of the pipe, the higher the strength. Good comprehensive performance.

When rolling with large deformation, the material flow is banded, while when rolling with small deformation, the material flow is bunched. Under the condition of inter-pass heat treatment and the same rolling process, the microstructure distortion of the pipe with large deformation is more serious.

The small deformation of the blank has little effect on the anisotropy of the pipe. The anisotropy of mechanical properties fluctuates in multipass rolling.