Method for manufacturing high-strength titanium alloy pipe

Abstract

The application relates to the field of materials and metallurgical technology, in particular to a preparation method of high-strength titanium alloy pipe, which comprises the following components in percentage by weight: Zr: 8-12%, Al: 4-6%, V: 3-5%, B: 0.08-0.12%, and the balance is Ti and inevitable impurities; and the preparation method comprises the following steps: a melting process, a cross piercing process, a radial forging process, a heat treatment process, a warm rolling process, a chemical cleaning process and a composite polishing process. The high-strength titanium alloy pipe contains a certain content of Zr and B elements, the corrosion resistance of the titanium alloy pipe is improved, the grain is obviously refined through the synergistic effect, the creep stress at 600 DEG C is greater than or equal to 350 MPa, and the high-temperature stability of the titanium alloy is improved; the vacuum self-consumption electrode melting furnace and the EB furnace melting process can eliminate inclusions and segregation, so that the purity of the ingot is high, and the titanium alloy pipe prepared through the preparation method meets the use requirements of the pipeline of an aero-engine.

Description

Technical Field

[0001] This invention relates to the fields of materials and metallurgy, and in particular to a method for preparing high-strength titanium alloy pipes. Background Technology

[0002] Titanium alloy tubing is the preferred material for aero-engine piping due to its high strength, excellent corrosion resistance, and biocompatibility. However, current titanium alloy tubing is mainly manufactured through multi-pass cold rolling and annealing processes. During the deformation process, excessive elongation of the β-phase grains leads to anisotropy, resulting in low transverse impact toughness and poor high-temperature stability, which does not meet the requirements for titanium alloy tubing in aero-engine piping. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a method for preparing high-strength titanium alloy pipes with good high-temperature stability.

[0004] The technical solution adopted by the present invention to solve its technical problem is: a method for preparing high-strength titanium alloy pipes, wherein the high-strength titanium alloy pipes comprise the following components by weight percentage: Zr: 8-12%, Al: 4-6%, V: 3-5%, B: 0.08-0.12%, with the balance being Ti and unavoidable impurities.

[0005] The high-strength titanium alloy tube is obtained by sequentially performing a smelting process, a skew rolling and piercing process, a radial forging process, a heat treatment process, a warm rolling process, a chemical cleaning process, and a composite polishing process.

[0006] In the smelting process, the raw materials are first pressed into electrodes, and then the electrodes are smelted into ingots 1-2 times in a vacuum consumable electrode smelting furnace. Finally, the ingots are peeled and then smelted in an EB furnace once.

[0007] Furthermore, in the skew rolling piercing process, the ingot obtained in the smelting process is first machined into a billet of the required size. Then, the billet is heated to 900-950℃, held for 1-2 hours, and then skew rolling piercing is performed. The deformation is 40-60%, and the piercing speed of the tube billet is controlled at 400-600 mm / min to obtain a hollow tube billet.

[0008] Furthermore, in the radial forging process, the hollow tube blank is first heated to 900-950℃ in a box-type resistance furnace and held for 1.5-2 hours. Then, multiple radial forgings are performed, with a total deformation of 60-80% and a deformation of 20-30% for each radial forging pass. After radial forging, the tube blank is air-cooled to room temperature.

[0009] Furthermore, in the heat treatment process, the hollow tube blank after radial forging is first heated to 900-950℃, held for 1-1.5 hours and then air-cooled to room temperature. Then the hollow tube blank is heated to 800-850℃, held for 1-2 hours and then air-cooled to room temperature.

[0010] Furthermore, in the warm rolling process, the hollow tube blank is subjected to multiple warm rolling passes at a temperature of 800-850℃, with a final rolling temperature of not less than 750℃. The deformation amount per pass is 30-50%. After each pass of warm rolling, recrystallization annealing treatment is carried out at 750-800℃ for 1-2 hours, with a cumulative deformation amount ≥85%, to obtain the tube body.

[0011] Furthermore, in the chemical cleaning process, the pipe body is first ultrasonically cleaned with sodium hydroxide solution or potassium hydroxide solution to remove grease, and then acid pickling is used to remove the oxide layer.

[0012] Furthermore, in the composite polishing process, the tube body is first electrolytically polished, and then magnetorheologically polished to obtain the high-strength titanium alloy tube.

[0013] The beneficial effects of this invention are as follows: The high-strength titanium alloy pipe of this invention contains a certain amount of Zr and B elements, which improves the corrosion resistance of the titanium alloy pipe. Their synergistic effect significantly refines the grains, and the creep stress at 600℃ is ≥350MPa, which significantly improves the high-temperature stability of the titanium alloy. Furthermore, the composite process of vacuum consumable electrode melting furnace and EB furnace melting can eliminate inclusions and segregation, resulting in a high purity of ingot (O≤0.15%). Combined with the preparation method of this invention, the prepared titanium alloy pipe meets the requirements for use in aero-engine pipelines. Detailed Implementation

[0014] The present invention discloses a method for preparing high-strength titanium alloy tubing. The high-strength titanium alloy tubing comprises the following components by weight percentage: Zr: 8-12%, Al: 4-6%, V: 3-5%, B: 0.08-0.12%, with the balance being Ti and unavoidable impurities.

[0015] The high-strength titanium alloy tube is obtained by sequentially performing a smelting process, a skew rolling and piercing process, a radial forging process, a heat treatment process, a warm rolling process, a chemical cleaning process, and a composite polishing process.

[0016] In the smelting process, the raw materials are first pressed into electrodes, and then the electrodes are smelted into ingots 1-2 times in a vacuum consumable electrode smelting furnace. Finally, the ingots are peeled and then smelted in an EB furnace once. EB furnace smelting is electron beam smelting.

[0017] To facilitate the acquisition of each element, the preferred raw materials are sponge titanium (purity ≥99.9%), sponge zirconium (Zr+Hf≥99.5%), aluminum-vanadium master alloy and aluminum briquettes (Al≥99.9%), and high-purity boron powder (B≥99.5%).

[0018] To ensure the production of titanium alloy tubes that meet the requirements for use in aero-engine piping, the specific parameters for each process are as follows: In the skew rolling and piercing process, the ingot obtained in the melting process is first machined into a billet of the required size. Then, the billet is heated to 900-950℃, held for 1-2 hours, and then skew rolled and pierced. The deformation is 40-60%, and the piercing speed of the billet is controlled at 400-600 mm / min to obtain a hollow billet.

[0019] In the radial forging process, the hollow tube blank is first heated to 900-950℃ in a box-type resistance furnace and held for 1.5-2 hours. Then, multiple radial forgings are performed, with a total deformation of 60-80% and a deformation of 20-30% for each radial forging pass. After radial forging, the tube blank is air-cooled to room temperature.

[0020] In the heat treatment process, the hollow tube blank after radial forging is first heated to 900-950℃, held for 1-1.5h and then air-cooled to room temperature. Then the hollow tube blank is heated to 800-850℃, held for 1-2h and then air-cooled to room temperature.

[0021] In the warm rolling process, the hollow tube billet is subjected to multiple warm rolling passes at a temperature of 800-850℃, with a final rolling temperature of not less than 750℃. The deformation per pass is 30-50%. After each pass of warm rolling, recrystallization annealing is performed at 750-800℃ for 1-2 hours. The cumulative deformation is ≥85%, resulting in the tube body.

[0022] In the chemical cleaning process, the pipe body is first ultrasonically cleaned (40kHz, 30min) with sodium hydroxide solution or potassium hydroxide solution to remove grease, and then acid-washed (HF:HNO3:H2O=1:3:10 volume ratio, 25℃×20-25min) to remove the oxide layer.

[0023] In the composite polishing process, the pipe body is first electrolytically polished with perchloric acid-acetic acid (1:9 volume ratio) as the electrolyte, 30V voltage, 0.8A / cm² current density, and 250-280min time to remove microscopic protrusions on the surface. Then, magnetorheological polishing is performed using diamond abrasive (0.3-0.5μm particle size, 15% volume fraction) and a magnetic field strength of 0.8T. After polishing, the surface roughness Ra≤0.04μm (inner wall) and Ra≤0.03μm (outer wall) are achieved.

[0024] In summary, the high-strength titanium alloy pipe of this invention incorporates a certain amount of Zr and B elements, which improves the corrosion resistance of the titanium alloy pipe. Their synergistic effect significantly refines the grain size, resulting in a creep stress of ≥350MPa at 600℃ and enhancing the high-temperature stability of the titanium alloy. Furthermore, the combined process of vacuum consumable electrode melting furnace and EB furnace melting can eliminate inclusions and segregation, resulting in a high ingot purity (O≤0.15%). The use of multi-fire secondary diameter forging + dynamic warm rolling further refines the grain size, achieving a room temperature tensile strength ≥1100MPa and an elongation ≥10%, with overall performance superior to traditional rolling processes. The composite polishing technology applied to the pipe surface reduces the inner and outer wall roughness Ra≤0.05μm, decreasing fluid resistance by 20%-30% and extending fatigue life. Combined with the preparation method of this invention, the titanium alloy pipe produced meets the requirements for use in aero-engine piping.

[0025] Example 1.

[0026] The present invention discloses a method for preparing high-strength titanium alloy tubing, wherein the high-strength titanium alloy tubing comprises the following components by weight percentage: Zr: 8.5%, Al: 4.5%, V: 3.8%, B: 0.1%, with the balance being Ti and unavoidable impurities; The high-strength titanium alloy tube is obtained by sequentially performing a smelting process, a skew rolling and piercing process, a radial forging process, a heat treatment process, a warm rolling process, a chemical cleaning process, and a composite polishing process. In the smelting process, the raw materials are first pressed into Φ400mm electrodes. Then, the electrodes are smelted twice in a vacuum consumable electrode smelting furnace to form Φ650mm ingots. Finally, the ingots are peeled off the surface layer by 8mm and then smelted once in an EB furnace with an accelerating voltage of 36kV and a melting rate of 10kg / min.

[0027] In the skew rolling piercing process, the ingot obtained in the smelting process is first machined into a Φ180mm billet. Then, the billet is heated to 920℃, held for 1.5h, and then skew rolling piercing is performed with a deformation of 50%. The piercing speed of the tube billet is controlled at 200mm / min to obtain a Φ110×15mm hollow tube billet.

[0028] In the radial forging process, the hollow tube blank is first heated to 930℃ in a box-type resistance furnace and held for 2 hours. Then, it is subjected to three radial forging passes with a total deformation of 70% and a deformation of 25% for each pass. After radial forging, it is air-cooled to room temperature.

[0029] In the heat treatment process, the hollow tube blank after radial forging is first heated to 950℃, held for 1 hour and then air-cooled to room temperature. Then the hollow tube blank is heated to 820℃, held for 1.5 hours and then air-cooled to room temperature.

[0030] In the warm rolling process, the hollow tube billet is subjected to three warm rolling passes at a temperature of 820℃, with a final rolling temperature of 760℃. The deformation per pass is 40%. After each warm rolling pass, a recrystallization annealing treatment is performed at 780℃ for 1 hour, resulting in a cumulative deformation of 85% and obtaining a Φ70×3mm tube body.

[0031] In the chemical cleaning process, the pipe body is first ultrasonically cleaned (40kHz, 30min) with sodium hydroxide solution or potassium hydroxide solution to remove grease, and then acid-washed (HF:HNO3:H2O=1:3:10 volume ratio, 25℃×20min) to remove the oxide layer.

[0032] In the composite polishing process, the pipe body is first electrolytically polished with perchloric acid-acetic acid (1:9 volume ratio) as the electrolyte, 30V voltage, 0.8A / cm² current density, and 250min time to remove microscopic protrusions on the surface. Then, magnetorheological polishing is performed using diamond abrasive (0.4μm particle size, 15% volume fraction) and a magnetic field strength of 0.8T. After polishing, the surface roughness Ra = 0.04μm (inner wall) and Ra = 0.03μm (outer wall).

[0033] Testing revealed that the high-strength titanium alloy tubing prepared in this embodiment exhibits the following room-temperature mechanical properties: tensile strength: 1120 MPa, yield strength: 980 MPa, elongation: 12%. High-temperature creep (600℃ × 100 h, stress 350 MPa): creep strain 0.8%. Corrosion resistance: after immersion in 3.5% NaCl solution for 30 days, the annual corrosion rate is 0.004 mm / a, with no pitting corrosion, meeting the requirements for use in aero-engine piping.

[0034] Example 2.

[0035] The present invention discloses a method for preparing high-strength titanium alloy tubing, wherein the high-strength titanium alloy tubing comprises the following components by weight percentage: Zr: 11.5%, Al: 5.5%, V: 4.5%, B: 0.12%, with the balance being Ti and unavoidable impurities; The high-strength titanium alloy tube is obtained by sequentially performing a smelting process, a skew rolling and piercing process, a radial forging process, a heat treatment process, a warm rolling process, a chemical cleaning process, and a composite polishing process. In the smelting process, the raw materials are first pressed into Φ420mm electrodes. Then, the electrodes are smelted twice in a vacuum consumable electrode smelting furnace to form Φ750mm ingots. Finally, the ingots are peeled off the surface layer by 10mm and then smelted once in an EB furnace with an accelerating voltage of 40kV and a melting rate of 12kg / min.

[0036] In the skew rolling piercing process, the ingot obtained in the smelting process is first machined into a Φ190mm billet. Then, the billet is heated to 940℃, held for 2 hours, and then skew rolling piercing is performed. The deformation is 58%, and the piercing speed of the tube billet is controlled at 200mm / min to obtain a Φ120×18mm hollow tube billet.

[0037] In the radial forging process, the hollow tube blank is first heated to 950℃ in a box-type resistance furnace and held for 1.8 hours. Then, it undergoes four radial forging passes with a total deformation of 75% and a deformation of 28% for each pass. After radial forging, it is air-cooled to room temperature.

[0038] In the heat treatment process, the hollow tube blank after radial forging is first heated to 980℃, held for 1.2 hours and then air-cooled to room temperature. Then the hollow tube blank is heated to 840℃, held for 2 hours and then air-cooled to room temperature.

[0039] In the warm rolling process, the hollow tube blank is subjected to 4 passes of warm rolling at a temperature of 840℃, with a final rolling temperature of 750℃. The deformation per pass is 45%. After each pass of warm rolling, a recrystallization annealing treatment is performed at 790℃ for 1 hour. The cumulative deformation is 88%, resulting in a Φ80×4mm tube body.

[0040] In the chemical cleaning process, the pipe body is first ultrasonically cleaned (40kHz, 30min) with sodium hydroxide solution or potassium hydroxide solution to remove grease, and then acid-washed (HF:HNO3:H2O=1:3:10 volume ratio, 25℃×22min) to remove the oxide layer.

[0041] In the composite polishing process, the pipe body is first electrolytically polished with perchloric acid-acetic acid (1:9 volume ratio) as the electrolyte, 30V voltage, 0.8A / cm² current density, and 280min time to remove microscopic protrusions on the surface. Then, magnetorheological polishing is performed using diamond abrasive (0.4μm particle size, 15% volume fraction) and a magnetic field strength of 0.8T. After polishing, the surface roughness Ra = 0.043μm (inner wall) and Ra = 0.032μm (outer wall).

[0042] Testing revealed that the high-strength titanium alloy tubing prepared in this embodiment exhibits the following room-temperature mechanical properties: tensile strength: 1180 MPa, yield strength: 1050 MPa, elongation: 10.2%. High-temperature creep (600℃ × 100 h, stress 350 MPa): creep strain 0.6%. Corrosion resistance: after immersion in 3.5% NaCl solution for 30 days, the annual corrosion rate is 0.003 mm / a, with no pitting corrosion, meeting the requirements for use in aero-engine piping.

Claims

1. A method for preparing high-strength titanium alloy tubing, characterized in that: High-strength titanium alloy tubing is used in aero-engine piping. By weight percentage, high-strength titanium alloy tubing comprises the following components: Zr: 8-12%, Al: 4-6%, V: 3-5%, B: 0.08-0.12%, with the balance being Ti and unavoidable impurities. The raw materials are sponge titanium with a purity of ≥99.9%, sponge zirconium with Zr+Hf ≥99.5%, aluminum-vanadium master alloy, aluminum briquettes with Al ≥99.9%, and high-purity boron powder with B ≥99.5%. The materials are then processed sequentially through smelting, skew rolling and piercing, radial forging, heat treatment, warm rolling, chemical cleaning, and composite polishing processes to obtain the high-strength titanium alloy tube. In the smelting process, the raw materials are first pressed into electrodes, and then the electrodes are smelted into ingots 1-2 times in a vacuum consumable electrode smelting furnace. Finally, the ingots are peeled and then smelted once in an EB furnace to eliminate inclusions and segregation, and the ingot O ≤ 0.15% is controlled. In the skew rolling piercing process, the ingot obtained in the smelting process is first machined into a billet of the required size. Then, the billet is heated to 900-950℃, held for 1-2 hours, and then skew rolling piercing is performed. The deformation is 40-60%, and the piercing speed of the tube billet is controlled at 400-600 mm / min to obtain a hollow tube billet. In the radial forging process, the hollow tube blank is first heated to 900-950℃ in a box-type resistance furnace and held for 1.5-2 hours. Then, multiple radial forgings are performed, with a total deformation of 60-80% and a deformation of 20-30% for each radial forging. After radial forging, the tube blank is air-cooled to room temperature. In the heat treatment process, the hollow tube blank after radial forging is first heated to 900-950℃, held for 1-1.5h and then air-cooled to room temperature. Then the hollow tube blank is heated to 800-850℃, held for 1-2h and then air-cooled to room temperature. In the warm rolling process, the hollow tube billet is subjected to multiple warm rolling passes at a temperature of 800-850℃, with a final rolling temperature of not less than 750℃. The deformation amount per pass is 30-50%. After each pass of warm rolling, recrystallization annealing is performed at 750-800℃ for 1-2 hours. The cumulative deformation amount is ≥85%, and the tube body is obtained. In the composite polishing process, the tube body is first electrolytically polished, and then magnetorheologically polished to obtain the high-strength titanium alloy tube. The roughness Ra of the inner and outer walls of the high-strength titanium alloy tube is ≤0.05μm.

2. The method for preparing high-strength titanium alloy tubing as described in claim 1, characterized in that: In the chemical cleaning process, the pipe body is first ultrasonically cleaned with sodium hydroxide solution or potassium hydroxide solution to remove grease, and then acid pickling is used to remove the oxide layer.