Development of High Strength α+β Titanium Alloy Sheet

Japan's Nippon Steel & Sumitomo Metal Corporation has researched and developed the industrialized production technology of T5A-1Fe and T-Fe0.350 (Super-TIX800) high-strength a+B titanium alloy hot-rolled titanium strips. Due to the developed T-direction texture, the unidirectional hot-rolled sheet of this kind of titanium alloy has a large anisotropy of the material. For this reason, different process technologies have been developed to reduce the anisotropy of the material.

First, the heating temperature of the plate was tested. The results showed that the 100mm thick I5Al-lFe4.160 alloy slab can be smoothly rolled to 4mm by the hot rolling mill when heated at 1050°C above the β transformation point (1010°C). Then the amount of oxygen added (0.16%, 0.26%,

0.36%, mass fraction) on the plate texture. Studies have shown that when the amount of oxygen added is large, the texture of the hot-rolled sheet in the T direction is strong. When the oxygen addition amount is less than 0.26%, the unidirectional hot-rolled sheet will not produce excessive anisotropy, and sufficient strength and plastic matching can be obtained. Based on the above research results, 3.7 T-5A1-1F0.160 alloy ingots are used to prepare titanium alloy slabs (thickness 170mm) by hot forging, at 1050℃

Under heating, one-way hot rolling produces hot-rolled titanium strips with a thickness of 4mm. During the hot rolling process, the deformation resistance is small, and the edge cracks are few. It can be hot rolled smoothly. The cold rewinding and coiling properties of the hot-rolled titanium strips good. Mass production of several tons of hot-rolled titanium strip has been carried out.

In order to reduce the anisotropy caused by the T-direction texture, the effectiveness of two-stage heat treatment was discussed, that is, a solution treatment with water cooling at 975-1025°C for 1 hour, followed by a stabilization treatment with air cooling at 700°C for 2 hours. Experiments show that the one-way hot rolled Ti5A-lFe-

After the two-stage heat treatment of 0.260 alloy, the anisotropy of the sheet is reduced, while maintaining the same high strength as the hot-rolled state in the L and T directions, and the plasticity is higher.

Another method to reduce the anisotropy of high-strength α+β titanium alloy unidirectional hot-rolled sheet is to carry out cold rolling and annealing treatment under appropriate conditions, and use large reduction (50%) for T-lFe0.350 hot-rolled sheet Processing rate) cold rolled and then annealed at 800°C. Experiments show that the T-direction texture has changed a lot, and a recrystallized structure is formed, which reduces the anisotropy of the sheet.