Titanium tube production is currently widely used cold rolling process, its plastic deformation process and plate and bar there are obvious differences: first of all, the material is required to have a high plastic deformation capacity, the general material elongation should be greater than 20%, so the material suitable for titanium tube production in pure titanium TA1, TA2, in titanium alloy there are a small number of corrosion resistant titanium alloys such as TA9, TA10. Secondly, the diameter thickness ratio γ(thickness and diameter ratio) of the pipe is also an important factor affecting the cold rolling process, γ is greater than 0.1 called thick wall tube, thick wall tube rolling is prone to cracking, including small cracks and penetration cracks.
In some high temperature and high pressure situations in the chemical industry, the strength of pure titanium pipes is required to reach a higher level such as Gr.3, Gr.4, and at the same time, in order to ensure sufficient pressure resistance of the pipe, the wall thickness of the pipe is often larger. As mentioned above, the production difficulty of cold-rolled pipes increases with the increase of the strength level of titanium and the increase of the diameter thickness ratio γ, so the production of high-strength thick-wall pipes will be more difficult. The product yield is very low, and the production of thick wall high strength pure titanium tube is an urgent problem to be solved at present.
The beneficial effect is that by adding a small amount of Ni to strengthen titanium, the invention can obtain a high strength under the condition of ensuring a high plasticity of the pipe and achieve the purpose of strengthening and toughening, but can improve the corrosion resistance of the titanium material. At the same time, the structure of the pipe was refined by two steps of pre-rolling and forming rolling. And control the annealing process, reduce the rolling hardness, improve the toughness of the material, change the structure, refine the grain size, and then improve the performance. Then the grain of the titanium alloy is further refined by rapid cooling, so that its performance is more uniform, and the tensile strength and elongation of the pipe are double high. The finished pipe obtained by the invention can maintain excellent mechanical properties for a long time during subsequent deep processing and even under the working condition of subsequent products.
The microstructure of the pipe was refined by two steps of pre-rolling and forming rolling. And control the annealing process, reduce the rolling hardness, improve the toughness of the material, change the structure, refine the grain size, and then improve the performance. Then the grain of the titanium alloy is further refined by rapid cooling, so that its performance is more uniform, and the tensile strength and elongation of the pipe are double high. The finished pipe obtained by the invention can maintain excellent mechanical properties for a long time during subsequent deep processing and even under the working condition of subsequent products.
