Cold rolling technology of Ti-6Al-4V (Ti Grade 5) alloy tube

Ti-6Al-4V (Ti Grade 5) alloy is one of the most widely used titanium alloys at present, its high strength and good corrosion resistance, but it is difficult to see Ti-6Al-4V seamless titanium tubes in the domestic and foreign seamless titanium tube market.

Ti-6Al-4V titanium material is mainly plate, and Ti-6Al-4V titanium pipe on 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, the induction heating device is installed on the tube rolling machine. This processing equipment has complex structure, complicated process and high production cost. The main reason for the present situation is the high strength of Ti-6Al-4V titanium alloy and the difficulty of cold rolling forming. In order to solve the key technology of Ti-6Al-4V seamless tube cold rolling forming, a series of researches have been carried out jointly by the university and enterprise. Such as the use of direct cold rolling forming process to produce high-strength titanium alloy pipe, not only greatly reduce the production cost, but also meet the requirements of high performance applications of titanium alloy.

The tube billets were rolled into tubes with a total deformation of 70% by two passes and three passes respectively. Between passes, 800℃×1h vacuum annealing was carried out, and the cooling method was that the furnace was cooled to 500℃ and then the air was cooled to room temperature. The conclusion is that:

Under the condition of small deformation, the wall thickness deviation is small and the surface roughness is gradually reduced. The large deformation and the large wall thickness deviation will affect the wall thickness deviation of the pipe produced by subsequent passes of rolling.

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

When rolling with large deformation, the flow of the material is banded, and when rolling with small deformation, the flow of the material is bunched. Under the same conditions of heat treatment between passes and subsequent rolling process, the microstructure distortion of the billet with large deformation is more serious.

The effect of small deformation on the anisotropy of the pipe is not significant. The anisotropy of mechanical properties fluctuates in multi-pass rolling.