A method for processing ultra-high strength titanium alloy wire

Abstract

The application relates to a processing method of ultrahigh-strength titanium alloy wire, which comprises the following steps: (1) carrying out roundness regulation and skinning treatment on a rolling blank; (2) solid solution above 50 DEG C-100 DEG C of a phase transition point, heat preservation time is 10min-60min, and air cooling is carried out; (3) carrying out multi-pass cold drawing, and the deformation amount is controlled to be 20%-38%; (4) stress relief annealing at 600 DEG C-700 DEG C, carrying out unwinding and straightening by using a sine unwinder, cutting, and carrying out aging treatment to obtain wire finished products. Through the specific deformation method treatment of the TB9 titanium alloy wire and the optimization of the aging system, the problem that the mechanical property control of the TB9 is difficult is solved, the mechanical property of the TB9 titanium alloy solid solution state wire reaches the index requirements of AMS4958, the mechanical property of the solid solution + cold deformation state wire reaches the index requirements of AMS4957, and the 1600MPa grade use condition requirements are met.

Description

[0001] This invention is a divisional application based on the application filed on September 14, 2023, with application number 202311182408.0 and invention title "A processing method for ultra-high strength titanium alloy rods and wires". Technical Field

[0002] This invention relates to the field of machining technology, specifically a method for processing ultra-high strength titanium alloy wire. Background Technology

[0003] TB9 (corresponding to the foreign grade Ti-38644, also known as β-c) high-strength titanium alloy is a metastable β-titanium alloy with excellent comprehensive mechanical properties, good hardenability, room temperature deformation capability, and corrosion resistance, making it an ideal material for manufacturing fasteners and aerospace springs. The high-strength, high-toughness, lightweight TB9 titanium alloy not only meets strength requirements of 1300MPa to 1400MPa, but also exhibits excellent low-temperature performance at -100℃, making it ideal for manufacturing fastener parts resistant to -100℃ temperatures. Ti-38644 is a highly alloyed metastable β-type titanium alloy with a high content of β-stabilizing elements, and a molybdenum equivalent close to 20. Therefore, it can undergo various hot and cold forming processes, meaning that different strength and plasticity combinations can be achieved by changing the hot and cold forming processes and heat treatment specifications. High-strength titanium alloys refer to titanium alloys with a room temperature tensile strength between 1100-1400MPa. The initial commercial application of Ti-38644 alloy was as an aircraft spring, used in applications such as landing gear traction devices, door balancing devices, flight control devices, and hydraulic system reset devices. Ti-38644 alloy is also used as a high-strength fastener in aviation, aerospace, and shipbuilding, with fasteners using Φ4.75mm~Φ15.88mm material achieving strengths of 1240MPa~1450MPa.

[0004] The invention patent with announcement number CN107138523B discloses a rolling method for TB9 titanium alloy wire and rod. Specifically, it involves heating a TB9 titanium alloy forging billet above its phase transformation point for 40–150 minutes to obtain a rolled billet; then rolling the obtained billet in 6–14 passes using a rolling mill to obtain wire and rod of the target specifications; the deformation per rolling pass is 10%–15%; and there is a 5–10 second pause between rolling passes. However, this patent uses the same rolling method for both TB9 titanium alloy wire and rod. A single processing method cannot simultaneously achieve ultra-high strength in both the rod and wire, making mechanical property control difficult. Summary of the Invention

[0005] The purpose of this invention is to provide a processing method for ultra-high strength titanium alloy wire, which uses a targeted rolling method to roll TB9 titanium alloy wire to precisely control the mechanical properties of the finished product.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a method for processing ultra-high strength titanium alloy wire, comprising the following steps: (1) The rolled billet is rounded and peeled; (2) Solid solution is applied at 50℃-100℃ above the phase transition point, and the solution is held for 10min-60min, followed by air cooling; (3) After multiple cold drawing processes, the deformation is controlled to be 20%-38%; (4) Stress relief annealing at 600℃-700℃, followed by uncoiling and straightening using a sinusoidal uncoiling machine, cutting, and aging treatment to obtain the finished wire material.

[0007] Preferably, the rolled billet is a TB9 high-strength titanium alloy with a diameter of 9.5 mm.

[0008] Preferably, the diameter of the finished wire is 2.0 mm to 7.0 mm.

[0009] Preferably, the aging temperature T of the aging treatment is... β / α+β The following are the furnace temperatures: 150℃~300℃. After reaching the set temperature, the furnace is placed in the furnace and held for 4-30 hours before being removed and air-cooled.

[0010] The beneficial effects of this invention are: Cold drawing is used in the rolling of finished wire rods to increase the dislocation density within the grains, thereby accelerating the subsequent aging process and ensuring that the α phase precipitated during aging is uniform and dispersed. Cold deformation methods such as cold forging and cold drawing are employed. For finished bar rolling, cold forging is used to apply triaxial compressive stress, which makes the grain fragmentation more thorough.

[0011] This invention solves the problem of difficult mechanical property control of TB9 by using different rolling methods for TB9 titanium alloy wires and bars, combined with optimization of the aging regime. This enables the mechanical properties of TB9 titanium alloy solution-treated wires and bars to meet the AMS4958 index requirements, and the mechanical properties of solution-treated + cold-deformed wires and bars to meet the AMS4957 index requirements, thus satisfying the 1600MPa level service conditions. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the rolling process for the finished bar stock of the present invention; Figure 2 This is a schematic diagram of the wire rolling process of the present invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0014] refer to Figure 1 and Figure 2 This invention relates to a cold deformation production method for ultra-high strength TB9 titanium alloy rods and wires. The method produces rods with a diameter of Φ7.0mm to Φ25.4mm and wires with a diameter of Φ2.0mm to Φ7.0mm. The invention employs the following process: ① Hot-rolled bars with diameters of 9.5mm to 60mm are solution treated and then cold-deformed. The total deformation of the cold-deformed bars is controlled at 20% to 54%, which can effectively improve the microstructure of the metal. After machining processes such as peeling, cold straightening, and grinding, the final product is obtained. Solution treatment is a heat treatment process in which an alloy is heated to a high-temperature single-phase region and held at that temperature to allow the excess phase to fully dissolve into the solid solution, followed by rapid cooling to obtain a supersaturated solid solution. Its main purpose is to improve the plasticity and toughness of steel and alloys, and to prepare for precipitation hardening treatment.

[0015] ② For Φ9.5mm hot-rolled round billets, after intermediate annealing and cold drawing pass design, the drawing deformation of each pass is controlled at 20% to 54%, and the final drawing pass is performed after solution treatment, which can effectively improve the metal structure and properties in the final aged state.

[0016] ③ For ① and ② above, perform aging treatment on the rod and wire materials at an aging temperature T. β / α+β The product is placed in the furnace at 150℃~300℃, held for 4-30 hours, and then air-cooled after removal from the furnace, which can enhance the performance of the aged product.

[0017] The technical solution and specific implementation methods of the invention will be described in detail below.

[0018] The technical solution of this invention is as follows: 1. Rolled bar billet → Round forging → Solution treatment → Cold deformation → Peeling → Cold straightening → Finished bar product machining.

[0019] 2. Rolled coil billet → stripping the outer layer of the coil → solution treatment → cold drawing → stress-relief annealing → uncoiling and straightening → machining of finished wire.

[0020] The rounding of rolled bar billets is carried out using a rotary forging machine, while the rounding of rolled coil billets is carried out using a coiling device and a wire drawing machine.

[0021] refer to Figure 1 Taking the production of Φ10.5mm TB9 titanium alloy bars as an example, the operation steps of this invention are as follows: Step 1: First, the Φ15mm rolled billet is forged into a diameter of Φ14.5±0.2mm by rotary forging. Step 2: Solvent at 60-90℃ above the phase transition point, hold for 15-60 minutes, then air cool; Step 3: After multiple passes of rotary forging, ensure that the cold deformation is between 20% and 54%; Step 4: Finally, peel off the outer layer to remove surface defects from the rotary forging process, then straighten the surface using a two-roll straightener, and finally machine it to the finished product specifications. Step 5: Aging temperature T β / α+β The following temperatures (150℃~300℃) are used to heat the material in the furnace. After holding at this temperature for 4-30 hours, the material is removed from the furnace and air-cooled to enhance the performance of the aged product. The properties of the produced Φ10.5mm TB9 titanium alloy wire are shown in Table 1.

[0022] Table 1

[0023] refer to Figure 2 Taking the production of Φ6.5mm TB9 titanium alloy wire as an example, the operation steps of this invention are as follows: Step 1: First, the Φ9.5mm rolled billet is rounded and peeled off to a size of Φ8.5±0.2mm; Step 2: Solidify at 50℃-100℃ above the phase transition point, hold for 10min-60min, then air cool; Step 3: After multiple drawing passes, ensure that the deformation is between 20% and 38%; Step 4: Finally, stress-relief annealing at 600℃-700℃, followed by uncoiling and straightening using a sine uncoiler, and cutting into straight filaments. The final machining process produces the finished product specifications. Step 5: Aging temperature T β / α+β The wire is heated to 150℃~300℃, placed in the furnace, held for 4-30 hours, and then air-cooled. The properties of the produced Φ6.5mm TB9 titanium alloy wire are shown in Table 2.

[0024] Table 2

[0025] This invention, through a unique cold deformation processing technology combined with an optimized aging regime, can solve the problem of the difficulty in controlling the mechanical properties of TB9, enabling the mechanical properties of TB9 titanium alloy solution-treated bars and wires to meet the requirements of AMS4958, and the mechanical properties of solution-treated + cold-deformed bars and wires to meet the requirements of AMS4957.

[0026] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for processing ultra-high strength titanium alloy wire, characterized in that, Includes the following steps: (1) The rolled billet is rounded and peeled; (2) Solid solution is applied at 50℃-100℃ above the phase transition point, and the solution is held for 10min-60min, followed by air cooling; (3) After multiple cold drawing processes, the deformation is controlled to be 20%-38%; (4) Stress relief annealing at 600℃-700℃, followed by uncoiling and straightening using a sinusoidal uncoiling machine, cutting, and aging treatment to obtain the finished wire material.

2. The processing method for ultra-high strength titanium alloy wire according to claim 1, characterized in that, The rolled billet is a TB9 high-strength titanium alloy with a diameter of 9.5 mm; The diameter of the finished wire is 2.0 mm to 7.0 mm.

3. The processing method for ultra-high strength titanium alloy wire according to claim 1, characterized in that, The aging temperature T of the aging treatment β / α+β The following are the furnace temperatures: 150℃~300℃. After reaching the set temperature, the furnace is placed in the furnace and held for 4-30 hours before being removed and air-cooled.

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