Rolling technology of Ti-6AL-4V titanium alloy tube

Titanium alloys are like many alloy metals. To meet the requirements of material properties, but its main components of titanium accounted for more than 90%. Two alloys widely used in aerospace technology, Ti-6Al-4V(6 % aluminum, 4% vanadium, 90% titanium) and Ti-3Al-2.5V is (3 % aluminum, 2.5% vanadium, 94.5% titanium). Ti-3Al-2.5V is used to manufacture high-strength pipe materials, Ti6AL4V is mainly used in the aerospace field of fuselage manufacturing. Titanium tube is an indispensable important information for the development of the nuclear industry, in addition to the above uses, many equipment, pipes and related components used in nuclear reactors, in addition to the use of zirconium, hafnium, but also need a large number of titanium tube and titanium alloy tube materials. With the further development of the nuclear industry, the value of titanium tubes will certainly be more reflected.

Ti-6AL-4V titanium 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 the wall thickness deviation is small and the surface roughness is gradually reduced under the condition of small deformation. 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. The effect of small deformation on the anisotropy of the pipe is not significant. The anisotropy of mechanical properties fluctuates in multi-pass rolling. 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.