The invention relates to a processing method for metastable β type titanium alloy plate, belonging to the technical field of titanium alloy processing. The purpose of the invention is to overcome the deficiency of the existing technology, provide a processing technology for ti-15-3 alloy plate, and improve the cold working performance of the alloy. The processing method of the present invention includes the following steps: after melting into ingots, install the furnace at 800℃ ~ 850℃ and hold the ingots for 100-150 minutes, then heat up to 1100℃ ~ 1150℃ and hold the ingots for 240 ~ 360 minutes. After many upsetting, complete the first fire; Then after a one-way drawing to complete the blank blank; The hot rolled slab with thickness of 4mm ~ 10mm is rolled under the temperature of 850℃ ~ 1000℃. After annealing and alkali pickling, cold rolling is carried out to the sheet with thickness of 1-3mm. By controlling rolling temperature, deformation degree and cooling speed after deformation, the invention controls the structure of forging billet, makes it fully broken, effectively restrains the phase precipitation that causes the alloy to become brittle, so as to improve the plasticity and cold working performance.
At first, β type titanium alloy has high strength and excellent cold working performance, but the application of β type titanium alloy is hindered by unfavorable factors such as brittleness (such as Ti-13V-LLCR-3Al) or segregation (such as Ti-11.5Mo-6Zr-4.5 Sn) due to the precipitation of intermetallic compounds. In 1981, The United States TIMET company developed ti-15-3 alloy, the alloy contains isocrystalline β stable element V, eutectoid β stable element Cr, neutral element Sn and α stable element Al, its nominal composition is Ti-15V-3Cr-3Sn-3Al, is a kind of metastable β titanium alloy. The alloy has high strength, high toughness, no segregation in casting, excellent cold rolling and cold forming properties, and the cold rolling deformation can reach more than 90%. Through aging treatment, the room temperature strength can reach 1080MPa, mainly used for manufacturing various sheet metal components and fasteners. Solution treatment state can work below 200°C, solution aging state can work at 290°C.
The alloy is a metastable β type alloy, containing β stable elements above critical concentration, a small amount of Al and neutral elements. Existing processing technology: after three times of vacuum consumable electric arc melting, after surface cleaning, four times of unilateral drawing at 1050°C ~ 1150°C, and then hot rolling at 950°C ~ 1000°C, and then annealing at 760V ~ 850°C, cold rolling cracking phenomenon appeared. Due to improper hot working and heat treatment process, the plasticity of the alloy at room temperature becomes worse, which makes cold working difficult and the product performance difficult to meet the requirements.
