The preparation process of titanium alloy wire is characterized by: selecting TC17 titanium alloy to be rolled into a disc element with a specification of Φ12mm; the Φ12mm disc element undergoes three rounds of grinding; after grinding and reaching a total processing rate of 30%, it undergoes heat treatment, which is carried out in an electric furnace or vacuum furnace for stress relief annealing; when the wire diameter is ≥ Φ10mm, the stretching temperature is 780℃ ± 20℃; when the wire diameter is < Φ10mm, the stretching temperature is 730℃ ± 20℃; after heat treatment, the wire is repeatedly annealed, stretched, ground, and annealed until ≥ Φ5.5mm, and then undergoes vacuum heat treatment; before the finished product is sent out, it undergoes vacuum heat treatment, and according to the size of the finished product, a 0–5° internal and external conical angle round-edge mold is used to remove the lubricant and oxide skin impurity layer on the surface of the material, and then it is drawn into ≤ Φ5.0mm bright wire, followed by finished product inspection; after the finished product passes the inspection, it is used as the finished product and leaves the factory. This invention fills the gap in China's inability to produce TC17 titanium alloy wire.
Titanium alloy is the national standard designation of China, and the similar foreign brand is Ti-17 in the United States. The chemical composition is: Al: 4.5–5.5, Sn: 1.6–2.4, Zr: 1.6–2.4, Mo: 3.5–4.5, Cr: 3.5–4.5, with the remainder being Ti.
Titanium alloy has the advantages of high tensile strength and creep strength, good fracture toughness, and a wide forging temperature range. It can meet the requirements of damage tolerance design, high structural efficiency, high reliability, and low manufacturing cost. China began to develop TC17 titanium alloy during the 7th Five-Year Plan period. At present, the products are mainly bars, forgings, and slabs, and have been applied in aerospace, aero-engine fans, compressor discs, and other fields. In the future, with the development of China's aerospace industry and large aircraft projects, the application prospects will be even broader.
However, at present, there is no corresponding production standard for TC17 titanium alloy wire in China, and the applicant has not found any relevant materials on the preparation process of TC17 titanium alloy wire in foreign countries. The existing titanium and titanium alloy wire preparation processes cannot meet the requirements of titanium alloy wire for aerospace and aviation applications, due to the widespread use of alkaline and acidic washing to remove oxide skin and lubricants from the finished wire. In addition, the semi-finished TC17 wire also has the characteristics of large deformation force and high strength during stretching, and often breaks after one stretch. Therefore, up to now, no mature preparation process for TC17 titanium alloy wire has emerged.
Preparation process of TC17 titanium alloy wire
(1)Rolling disc element: Select qualified TC17 titanium alloy Φ60mm or Φ55mm square bars, and roll them into a disc element with a specification of Φ12mm in the β phase region at 930℃ ± 20℃, with the final rolling temperature controlled above 600℃.
(2)Grinding: The Φ12mm disc element undergoes the first grinding treatment for surface defects before drawing, the second grinding treatment after drawing to Φ10mm and peeling processing, and the third grinding treatment after peeling processing to Φ6mm, to ensure that the surface of the finished product has no holes, cracks, or inclusion defects.
(3)Heat treatment: After each grinding and when the total processing rate reaches 30%, heat treatment is carried out at a temperature ranging from 780℃ ± 10℃ to 720℃ ± 10℃, holding for 2 hours, air cooling, and stress relief annealing in an electric furnace or vacuum furnace.
(4)Stretching temperature: When the wire diameter is ≥ Φ10mm, the stretching temperature is 780℃ ± 20℃; when the wire diameter is < Φ10mm, the stretching temperature is 730℃ ± 20℃.
(5)Stretching: After heat treatment, the wire undergoes a processing rate of 5–10% per pass, with the total processing rate not exceeding 35%. It is repeatedly annealed, stretched, ground, and annealed until Φ3.3 ± 0.1mm, with a stretching temperature of 750℃ ± 10℃. Stretch to Φ3.15mm wire material and perform vacuum heat treatment at 750℃ ± 10℃. During stretching, attention should be paid to avoiding scratches or peeling on the surface of the wire material.
(6)Finished product: After vacuum heat treatment of the Φ3.15mm wire material, a 2° internal and external conical angle round-edge mold is used to remove the lubricant and oxide skin impurity layer on the surface of the material, and then stretch it into a Φ3.0mm bright wire. It is then subjected to finished product inspection. The processing temperature does not exceed 720℃ ± 10℃ to avoid secondary oxidation due to excessive temperature.
(7)Finished product inspection: Remove the stretching shrinkage holes at the head and tail of the wire material, and repeatedly visually inspect the surface for impurity residues, cracks, holes, inclusions, etc. After passing the visual inspection, take samples and send them to a testing institution for analysis and comparison of the original chemical composition, which serves as the basis for issuing a qualified material certificate for the finished product to be delivered.
