Ti-al-sn based titanium alloy bar with ordered phase strengthening and preparation method thereof

Abstract

This invention relates to an ordered phase-strengthened Ti-Al-Sn titanium alloy bar and its preparation method, belonging to the technical field of titanium-based metal materials. The preparation method includes a square billet undergoing two upsetting cycles (one heat, two passes) to obtain a first-stage alloy billet, followed by four gradient incremental upsetting cycles (one heat, four passes) to obtain a second-stage alloy billet. This is then repeated four times (one heat, four passes) to obtain a third-stage alloy billet. The third-stage alloy billet is then heated and sequentially shaped, drawn, and rounded to form a bar. The heat treatment of the bar is optimized to obtain the Ti-Al-Sn titanium alloy bar. This invention utilizes stepped heating and gradient deformation control to achieve ordered phase transformation and grain refinement. This method can solve technical problems such as high deformation resistance, easy cracking, uneven microstructure, and low yield in ordered phase alloys, thereby obtaining titanium alloy bars with uniform microstructure.

Description

Technical Field

[0001] This invention belongs to the field of titanium-based metal materials technology, specifically relating to an ordered phase-strengthened Ti-Al-Sn titanium alloy rod and its preparation method. Background Technology

[0002] Compared to traditional nickel-based superalloys, titanium alloys possess a significant advantage in specific strength and are considered key materials for achieving weight reduction in power equipment. They are widely used in core components such as aero-engine blades, casings, and combustion chambers. With the continuous increase in the thrust-to-weight ratio and service temperature of aerospace engines, higher demands are being placed on the service capabilities of titanium alloys under medium- and high-temperature conditions. Therefore, developing heat-resistant titanium alloys with higher operating temperatures to replace some nickel-based superalloys has always been an important goal in the field of aerospace materials.

[0003] Currently, maturely applied and independently developed high-temperature titanium alloys, such as near-α-type alloys like Ti60 and Ti65, have design operating temperatures reaching 600-650℃, representing an advanced level of high-temperature titanium alloys based on the Ti-Al binary system. Introducing the neutral element Sn into the Ti-Al system can yield novel thermodynamically more stable Ti-Al-Sn intermetallic compounds, exhibiting superior high-temperature phase stability and mechanical stability, providing a more promising titanium alloy system for the development of next-generation high-temperature alloys.

[0004] However, material systems based on ordered intermetallic compounds generally suffer from inherent high room temperature brittleness, narrow hot working windows, and difficulties in plastic forming, resulting in high difficulty, high cost, and low yield in traditional manufacturing processes such as forging and machining. These severe process bottlenecks greatly restrict the large-scale engineering application of ordered phase-strengthened titanium alloys. Therefore, it is urgent to explore a new forging process to improve the alloy's susceptibility to cracking and microstructure uniformity, thereby increasing the quality of bars and material utilization. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an ordered phase-strengthened Ti-Al-Sn titanium alloy rod and its preparation method. By controlling the step-heating and gradient deformation, the ordered phase transformation becomes a powerful tool for achieving grain refinement. This method can solve technical problems such as high deformation resistance, easy cracking, uneven microstructure, and low yield of ordered phase alloys, thereby obtaining titanium alloy rods with uniform microstructure.

[0006] The technical solution adopted in this invention is as follows: In a first aspect, the present invention provides a method for preparing Ti-Al-Sn titanium alloy rods with ordered phase reinforcement, comprising the following steps: S1. Pretreatment stage: Select alloy ingots, heat to 1150-1250℃, hold for 8-10 hours, remove from the furnace and shape into square billets, then return to the furnace and heat to 1150-1250℃ for later use. S2. First-stage upsetting and drawing forging: The square billet is upset twice (one heat, two passes) to obtain the first-stage alloy billet; the first heat is heated to 1150℃-1250℃ and held for 8-10 hours; the upsetting temperature decreases gradually in each pass, the upsetting deformation is 45-55%, and the upsetting deformation rate is 0.5-1 s. -1 The total forging ratio is 2-4; S3. Second-stage upsetting and forging: The first-stage alloy billet is upset four times in four stages (one heat, four cycles) to obtain the second-stage alloy billet; the first heat is heated to 1050-1080℃ and held for 6-8 hours; the upsetting deformation rate is 0.1-0.15 s⁻¹. -1 The total forging ratio is 5-8; S4. Third-stage upsetting and forging: The second-stage alloy billet undergoes four upsetting cycles (one heat, four passes) to obtain the third-stage alloy billet. The first heat cycle is heated to 1030-1050℃ and held for 4-6 hours, with an upsetting deformation of 35-45% and a deformation rate of 0.01-0.1 s⁻¹. -1 The total forging ratio is 2-5; S5. Final forging stage: The alloy billet of the third stage is heated to 1020-1030℃ and held for 4-6 hours. It is then shaped, drawn, and rolled to form a billet. The heat treatment is optimized to obtain the target titanium alloy bar (Ti-Al-Sn titanium alloy bar).

[0007] Furthermore, the height-to-diameter ratio of the square billet in step S1 is 1.5-3; preferably, the height-to-diameter ratio of the square billet is 2.

[0008] Furthermore, the step S2 of gradually reducing the upsetting temperature includes: the first upsetting temperature of the first stage of upsetting forging is 1150-1250℃, the second upsetting temperature of the first stage of upsetting forging is 1200-1250℃, the final forging temperature is not lower than 1050℃, and hot material is recycled back into the furnace for 2-4 hours in between.

[0009] By adopting the above technical solution and using gradient cooling forging, the internal grains of the alloy are gradually refined and homogenized, effectively avoiding the phenomenon of mixed grains.

[0010] Furthermore, step S3, the gradient incremental upsetting and drawing, includes: the first upsetting deformation is 25-30%, the second upsetting deformation is 30-35%, the third upsetting deformation is 35-40%, and the fourth upsetting deformation is 40-45%, with hot material being recycled back into the furnace for 1-3 hours in between.

[0011] Furthermore, in step S3, the final forging temperature of the second stage upsetting and drawing forging is not lower than 1000℃.

[0012] By adopting the above technical solution and using a strategy of gradually increasing deformation, the risk of cracking caused by deformation is reduced while ensuring the depth of deformation penetration.

[0013] Furthermore, the final forging temperature of the third stage upsetting and drawing forging described in step S4 is not lower than 980°C.

[0014] Furthermore, the elemental composition of the alloy ingot, by mass fraction, is as follows: Sn 10-15%, Al 5-8%, adjusting elements 1-5%, and the balance being Ti and unavoidable impurities, wherein the adjusting elements include W, Si and C.

[0015] Furthermore, the heat treatment optimization in step S5 includes heating the billet to 970-990°C, holding it at that temperature for 3-5 hours, and then air-cooling it to room temperature.

[0016] By adopting the above technical solution and optimizing the final heat treatment, the forging stress is eliminated while retaining the beneficial deformation structure characteristics, laying a good microstructure foundation for the subsequent final heat treatment.

[0017] Furthermore, before the pretreatment stage, the first stage of upsetting and drawing forging, the second stage of upsetting and drawing forging, the third stage of upsetting and drawing forging, and the final forging stage, an anti-oxidation coating is formed on the surface of the billet. The anti-oxidation coating can be any conventional anti-oxidation coating used in the art, and no further restrictions are imposed.

[0018] Furthermore, before the pretreatment stage, the first stage of upsetting and drawing forging, the second stage of upsetting and drawing forging, the third stage of upsetting and drawing forging, and the final forging stage, the billet is preheated to 950-970℃ and held for 4-6 hours.

[0019] Furthermore, after the first stage of upsetting and drawing forging, the second stage of upsetting and drawing forging, and the third stage of upsetting and drawing forging, there is also a slow cooling treatment and a surface treatment; the slow cooling treatment is to slowly cool from 500-700℃ to room temperature; the surface treatment is to grind and clean the surface.

[0020] Furthermore, the second-stage upsetting process also includes reversing upsetting.

[0021] Furthermore, the upsetting process in the third stage of upsetting forging also includes reversing upsetting.

[0022] By adopting the above technical solution, the reversing upsetting and drawing process after upsetting effectively breaks down dendritic segregation and directional structure in the casting structure, and promotes the formation of equiaxed fine grain structure.

[0023] Furthermore, the hammer and anvil temperatures during the first, second, and third stages of upsetting and drawing forging are not lower than 200°C, and the upper and lower end faces of the billet are covered with heat-insulating material; the heat-insulating material is an asbestos layer with a thickness greater than 20 mm.

[0024] Furthermore, the Ti-Al-Sn titanium alloy rod has a room temperature tensile strength ≥1190 MPa and an elongation ≥8%; a high temperature tensile strength of ≥650 MPa and an elongation ≥26% at 700℃.

[0025] Secondly, the present invention provides an ordered phase-strengthened Ti-Al-Sn titanium alloy rod, which is obtained by the above-mentioned method for preparing ordered phase-strengthened Ti-Al-Sn titanium alloy rods.

[0026] By adopting the technical solution of the present invention, a forging method for Ti-Al-Sn system titanium alloy ingots is designed to fully utilize the strong potential of ordered phases such as Ti8AlSn phase and Ti4AlSn2 phase while avoiding them from becoming crack sources, so that the ordered phases are conducive to processing and microstructure control.

[0027] Compared with the prior art, the beneficial effects of the present invention are: (1) Compared with traditional gradient heating or deformation, the preparation method of the present invention fully utilizes the powerful potential of the ordered phase. The preparation method of the present invention adopts gradient heating or deformation, which, compared with traditional high-temperature titanium alloys, can fully utilize the potential of the ordered phase while avoiding it from becoming a crack source, transforming the originally hard and brittle Ti-Al-Sn ordered phase from a "processing difficulty" into a "microstructure control tool". During the upsetting and drawing cycle, some undissolved ordered phases can act as nucleation points for recrystallization cores or inhibit grain boundary pinning, thereby refining the grains; at the same time, by using gradient deformation and multi-directional strain field construction, the orientation-selective flow of the ordered phase is utilized to control the texture gradient between the surface and core of the bar, eliminating anisotropy caused by uneven deformation.

[0028] (2) The titanium alloy rods prepared by the present invention exhibit excellent room temperature and high temperature properties. The room temperature tensile strength of the alloy is not less than 1190 MPa and the elongation is not less than 8%; the high temperature tensile strength at 700℃ is not less than 650 MPa and the elongation is not less than 26%.

[0029] (3) The titanium alloy rods prepared by this invention have the comprehensive advantages of high high temperature strength, good uniformity of structure and reliable processing performance. They can be used to prepare high temperature load-bearing rotating parts such as high pressure turbine disks, turbine shafts and integral bladed disks of aero engines. Compared with traditional high temperature titanium alloys, the service temperature can be increased by 50-100℃, which significantly improves the service life and service reliability of key components. Attached Figure Description

[0030] Figure 1 The image shows the microstructure of the titanium alloy rod prepared in Example 1 of this invention. Figure 2 The image shows the microstructure of the titanium alloy rod prepared in Example 2 of this invention. Figure 3 The image shows the microstructure of the titanium alloy rod prepared in Example 3 of this invention. Figure 4 This is a micrograph of the titanium alloy rod prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this application will be described in detail below with reference to specific examples. Unless otherwise defined, the technical and scientific terms used in this invention have the meanings commonly understood by those skilled in the art. Without departing from the concept of this invention, those skilled in the art can make various improvements and changes to the specific embodiments described in this specification, and all such improvements and changes fall within the scope of protection of this invention.

[0032] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0033] It should be noted that, for the sake of brevity, the room temperature in this invention is 25°C, and the specific room temperature will not be described separately in the following.

[0034] Example 1: This embodiment provides a method for preparing Ti-Al-Sn titanium alloy rods with ordered phase reinforcement, including the following steps: S1. Pretreatment stage: Select an alloy ingot with a specification of Φ300×800 mm. The elemental composition of the alloy ingot by mass fraction is: Sn 10.5%, Al 6.5%, W 2.0%, Si 0.4%, C 0.05%, with the balance being Ti and unavoidable impurities. An anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy ingot. It is preheated to 950℃ and held for 6 hours, then heated to 1180℃ and held for 8 hours. After being taken out of the furnace and shaped into a square billet with a height-to-diameter ratio of 2, it is returned to the furnace and heated to 1180℃ for later use.

[0035] S2. First-stage upsetting and forging: The square billet undergoes two upsetting processes (one heat and two passes) to obtain the first-stage alloy billet. The first heat is heated to 1200℃ and held for 8 hours. After exiting the furnace, it undergoes two further upsetting processes with progressively lower temperatures: the first upsetting temperature is 1200℃, and the second is 1150℃. A 4-hour hot-material reheating period is performed in between. The final forging temperature is not lower than 1050℃. The upsetting deformation in both processes is 45%, and the deformation rate is 0.5 s. -1 The total forging ratio is 2; The upsetting and drawing anvil temperature is 450℃, and the upper and lower end faces of the billet are covered with an asbestos layer with a thickness of 25 mm (the subsequent second-stage upsetting and drawing forging and the third-stage upsetting and drawing forging maintain this condition, which will not be repeated here).

[0036] The first-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the first-stage alloy billet is polished and cleaned. The specific method of polishing and cleaning is a conventional technique in this field, so it will not be described in detail.

[0037] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the first-stage alloy billet, and it is heated to 950℃ and held for 6 hours.

[0038] S3. Second-stage upsetting and forging: The first-stage alloy billet is upset four times in four stages (one heat, four cycles) to obtain the second-stage alloy billet; the first heat is heated to 1050℃ and held for 6 hours; the deformation rate is 0.1 s⁻¹. -1 The total forging ratio is 5; the first upsetting deformation is 25%, the second upsetting deformation is 30%, the third upsetting deformation is 35%, and the fourth upsetting deformation is 40%, with hot material being recycled back into the furnace for 2 hours in between. A 90° reversing upsetting process is performed after the second upsetting; the final forging temperature is not lower than 1000℃.

[0039] The second-stage alloy billet undergoes slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the second-stage alloy billet is polished and cleaned.

[0040] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the second stage, and the billet is heated to 950℃ and held for 4 hours.

[0041] S4. Third-stage upsetting and drawing forging: The second-stage alloy billet undergoes four upsetting and drawing cycles (one heat, four passes) to obtain the third-stage alloy billet. The first heat cycle is heated to 1030℃ and held for 6 hours. After removal from the furnace, it undergoes one upsetting and one drawing cycle, with an upsetting deformation of 35% and a deformation rate of 0.05 s⁻¹. -1After forging, the hot material is returned to the furnace and kept warm for 2 hours. The forging process is repeated four times, with a total forging ratio of 2. Among them, after the second upsetting, a 90° reversing upsetting is performed. The final forging temperature is not lower than 980℃.

[0042] The third-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the third-stage alloy billet is polished and cleaned.

[0043] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the third stage, and the temperature is heated to 950℃ and held for 4 hours.

[0044] S5. Final forging stage: The third-stage alloy billet is heated to 1020℃ and held for 4 hours. After being taken out of the furnace, it is shaped and drawn in an octagonal direction along the length of the billet. Then it is rolled into a bar billet with a size of Φ300×760mm. The bar billet is then subjected to heat treatment optimization (the bar billet is heated to 980℃, held for 4 hours, and air-cooled to room temperature) to obtain the target titanium alloy bar.

[0045] According to GB / T 5168-2020 "Test Methods for High and Low Magnification Microstructure of Titanium and Titanium Alloys", the microstructure of titanium alloy bar samples was characterized after grinding, polishing, and etching. Figure 1 As shown, the characterization results indicate that the alloy has a dual-state structure, with an average size of 9 μm for the primary α phase and a primary β grain size of 38 μm. The structure is uniform and defect-free.

[0046] According to GB / T 228.1-2021 "Metallic Materials - Tensile Testing", the tensile properties of titanium alloy bar specimens were tested. The test data are shown in Table 1. The results show that the room temperature tensile strength is not less than 1200 MPa and the elongation is not less than 8%; the high temperature tensile strength at 700℃ is not less than 650 MPa and the elongation is not less than 26%.

[0047] Table 1 Tensile property test data of Example 1

[0048] Example 2: This embodiment provides a method for preparing Ti-Al-Sn titanium alloy rods with ordered phase reinforcement, including the following steps: S1. Pretreatment stage: Select an alloy ingot with a specification of Φ300×800 mm. The elemental composition of the alloy ingot by mass fraction is: Sn 10%, Al 6.5%, W 2.5%, Si 0.4%, C 0.05%, with the balance being Ti and unavoidable impurities. An anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy ingot. It is preheated to 960℃ and held for 6 hours, then heated to 1200℃ and held for 8 hours. After being taken out of the furnace and shaped into a square billet with a height-to-diameter ratio of 2, it is returned to the furnace and heated to 1200℃ for later use.

[0049] S2. First-stage upsetting and forging: The square billet undergoes two upsetting processes (one heat and two passes) to obtain the first-stage alloy billet. The first heat is heated to 1220℃ and held for 8 hours. After exiting the furnace, it undergoes two further upsetting processes with progressively lower temperatures: the first upsetting temperature is 1220℃, and the second is 1170℃. A 4-hour hot-material reheating period is performed in between. The final forging temperature is not lower than 1050℃. The upsetting deformation in both processes is 50%, and the deformation rate is 0.8 s⁻¹. -1 The total forging ratio is 3; The first-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the first-stage alloy billet is polished and cleaned. The specific method of polishing and cleaning is a conventional technique in this field, so it will not be described in detail.

[0050] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the first-stage alloy billet, and it is heated to 960℃ and held for 6 hours.

[0051] S3. Second-stage upsetting and forging: The first-stage alloy billet is upset four times in four stages (one heat, four cycles) to obtain the second-stage alloy billet; the first heat is heated to 1060℃ and held for 6 hours; the deformation rate is 0.1 s⁻¹. -1 The total forging ratio is 6; the first upsetting deformation is 30%, the second upsetting deformation is 35%, the third upsetting deformation is 40%, and the fourth upsetting deformation is 45%, with hot material being recycled back into the furnace for 2 hours in between. A 90° reversing upsetting process is performed after the second upsetting; the final forging temperature is not lower than 1000℃.

[0052] The second-stage alloy billet undergoes slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the second-stage alloy billet is polished and cleaned.

[0053] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the second stage, and it is heated to 960℃ and held for 4 hours.

[0054] S4. Third-stage upsetting and drawing forging: The second-stage alloy billet undergoes four upsetting and drawing cycles (one heat, four passes) to obtain the third-stage alloy billet. The first heat cycle is heated to 1030℃ and held for 6 hours. After removal from the furnace, it undergoes one upsetting and one drawing cycle, with an upsetting deformation of 40% and a deformation rate of 0.06 s⁻¹. -1After forging, the hot material is returned to the furnace and kept warm for 2 hours. The forging process is repeated four times, with a total forging ratio of 3. Among them, after the second upsetting, a 90° reversing upsetting is performed. The final forging temperature is not lower than 980℃.

[0055] The third-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the third-stage alloy billet is polished and cleaned.

[0056] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the third stage, and the temperature is heated to 960℃ and held for 4 hours.

[0057] S5. Final forging stage: The third-stage alloy billet is heated to 1025℃ and held for 4 hours. After being taken out of the furnace, it is shaped and drawn in an octagonal direction along the length of the billet. Then it is rolled into a billet with a size of Φ300×760mm. The billet is then optimized by heat treatment (the billet is heated to 980℃, held for 4 hours, and air-cooled to room temperature) to obtain the target titanium alloy bar.

[0058] According to GB / T 5168-2020 "Test Methods for High and Low Magnification Microstructure of Titanium and Titanium Alloys", the microstructure of titanium alloy bar samples was characterized after grinding, polishing, and etching. Figure 2 As shown, the characterization results indicate that the alloy has a dual-state structure, with an average primary α phase size of 10 μm and an original β grain size of 49 μm. The structure is uniform and defect-free.

[0059] According to GB / T 228.1-2021 "Metallic Materials - Tensile Testing", the tensile properties of titanium alloy bar specimens were tested. The test data are shown in Table 2. The results show that the room temperature tensile strength is not less than 1230 MPa and the elongation is not less than 9%; the high temperature tensile strength at 700℃ is not less than 660 MPa and the elongation is not less than 27%.

[0060] Table 2 Tensile property test data table for Example 2

[0061] Example 3: This embodiment provides a method for preparing Ti-Al-Sn titanium alloy rods, including the following steps: S1. Pretreatment stage: Select an alloy ingot with a specification of Φ300×800 mm. The elemental composition of the alloy ingot by mass fraction is: Sn 10.5%, Al 6.5%, W 2.0%, Si 0.4%, C 0.05%, with the balance being Ti and unavoidable impurities. An anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy ingot. It is preheated to 970℃ and held for 6 hours, then heated to 1250℃ and held for 8 hours. After being taken out of the furnace and shaped into a square billet with a height-to-diameter ratio of 2, it is returned to the furnace and heated to 1250℃ for later use.

[0062] S2. First-stage upsetting and forging: The square billet undergoes two upsetting processes (one heat and two passes) to obtain the first-stage alloy billet. The first heat is at 1250℃ and held for 10 hours. After exiting the furnace, it undergoes two further upsetting processes with progressively lower temperatures: the first at 1250℃ and the second at 1200℃, with a 4-hour hot-material reheating period in between. The final forging temperature is not lower than 1050℃. The upsetting deformation in both processes is 50%, and the deformation rate is 1 s. -1 The total forging ratio is 4; The first-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the first-stage alloy billet is polished and cleaned. The specific method of polishing and cleaning is a conventional technique in this field, so it will not be described in detail.

[0063] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the first-stage alloy billet, and it is heated to 970℃ and held for 6 hours.

[0064] S3. Second-stage upsetting and forging: The first-stage alloy billet is upset four times in four stages (one heat, four cycles) to obtain the second-stage alloy billet; the first heat is heated to 1080℃ and held for 6 hours; the deformation rate is 0.15s. -1 The total forging ratio is 8; the first upsetting deformation is 30%, the second upsetting deformation is 35%, the third upsetting deformation is 40%, and the fourth upsetting deformation is 45%, with hot material being recycled back into the furnace for 2 hours in between. A 90° reversing upsetting process is performed after the second upsetting; the final forging temperature is not lower than 1000℃.

[0065] The second-stage alloy billet undergoes slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the second-stage alloy billet is polished and cleaned.

[0066] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the second stage, and it is heated to 970℃ and held for 6 hours.

[0067] S4. Third-stage upsetting and drawing forging: The second-stage alloy billet undergoes four upsetting and drawing cycles (one heat, four passes) to obtain the third-stage alloy billet. The first heat cycle is heated to 1050℃ and held for 4 hours. After removal from the furnace, it undergoes one upsetting and one drawing cycle, with an upsetting deformation of 45% and a deformation rate of 0.1 s⁻¹. -1After forging, the hot material is returned to the furnace and kept warm for 2 hours. The forging process is repeated four times, with a total forging ratio of 5. Among them, after the second upsetting, a 90° reversing upsetting is performed. The final forging temperature is not lower than 980℃.

[0068] The third-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the third-stage alloy billet is polished and cleaned.

[0069] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the third stage, and the temperature is heated to 970℃ and held for 4 hours.

[0070] S5. Final forging stage: The third-stage alloy billet is heated to 1030℃ and held for 4 hours. After being taken out of the furnace, it is shaped and drawn in an octagonal direction along the length of the billet. Then it is rolled into a bar billet with a size of Φ300×760mm. The bar billet is then subjected to heat treatment optimization (the bar billet is heated to 980℃, held for 4 hours, and air-cooled to room temperature) to obtain the target titanium alloy bar.

[0071] According to GB / T 5168-2020 "Test Methods for High and Low Magnification Microstructure of Titanium and Titanium Alloys", the microstructure of titanium alloy bar samples was characterized after grinding, polishing, and etching. Figure 3 As shown, the characterization results indicate that the alloy has a dual-state structure, with an average primary α phase size of 11 μm and an original β grain size of 58 μm. The structure is uniform and defect-free.

[0072] According to GB / T 228.1-2021 "Metallic Materials - Tensile Testing", the tensile properties of titanium alloy bar specimens were tested. The test data are shown in Table 3. The results show that the room temperature tensile strength is not less than 1190 MPa and the elongation is not less than 11%; the high temperature tensile strength at 700℃ is not less than 650 MPa and the elongation is not less than 25%.

[0073] Table 3 Tensile property test data table for Example 3

[0074] Example 4: This embodiment provides a method for preparing Ti-Al-Sn titanium alloy rods, which differs from Example 1 in that: S1. Pretreatment stage: Select an alloy ingot with a specification of Φ300×800 mm. The elemental composition of the alloy ingot by mass fraction is: Sn 15%, Al 5%, W 0.4%, Si 0.4%, C 0.2%, with the balance being Ti and unavoidable impurities. An anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy ingot. It is preheated to 970℃ and held for 6 hours, then heated to 1150℃ and held for 10 hours. After being taken out of the furnace and shaped into a square billet with a height-to-diameter ratio of 1.5, it is returned to the furnace and heated to 1250℃ for later use.

[0075] S2. First-stage upsetting and forging: The square billet is upset twice (one heat, two cycles) to obtain the first-stage alloy billet. The first heat is heated to 1150℃ and held for 10 hours. After exiting the furnace, it undergoes two upsetting processes with progressively lower temperatures: the first upsetting temperature is 1150℃, and the second upsetting temperature is 1250℃. The hot material is then returned to the furnace for 2 hours for holding. The final forging temperature is not lower than 1050℃. The upsetting deformation in both upsetting processes is 55%. The first-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 500℃, and the surface of the first-stage alloy billet is polished and cleaned. The specific method of polishing and cleaning is a conventional technique in this field, so it will not be described in detail.

[0076] S3. Second-stage upsetting and drawing forging: The first-stage alloy billet is upset and drawn four times in four stages with a gradient increment to obtain the second-stage alloy billet; wherein, the first stage heating temperature is 1050℃ and the holding temperature is 8 h. The second-stage alloy billet undergoes slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 500℃, and the surface of the second-stage alloy billet is polished and cleaned.

[0077] S4. Third-stage upsetting and drawing forging: The second-stage alloy billet is upset four times (one heat, four passes) to obtain the third-stage alloy billet; the deformation rate is 0.01 s. -1 .

[0078] The third-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 500℃, and the surface of the third-stage alloy billet is polished and cleaned.

[0079] S5. Final forging stage: Heat the third-stage alloy billet to 1020℃ and hold for 6 hours.

[0080] Example 5: This embodiment provides a method for preparing Ti-Al-Sn titanium alloy rods, which differs from Example 1 in that: S1. Pretreatment stage: Select an alloy ingot with a specification of Φ300×800 mm. The elemental composition of the alloy ingot by mass fraction is: Sn 13%, Al 8%, W 3%, Si 1%, C 1%, with the balance being Ti and unavoidable impurities. An anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy ingot. After being taken out of the furnace and shaped into a square billet with a height-to-diameter ratio of 3, it is returned to the furnace and heated to 1250℃ for later use.

[0081] S2. Slow cooling and surface treatment of the first-stage alloy billet: Slow cooling to room temperature in a resistance furnace at 700℃.

[0082] S3. Slow cooling and surface treatment of the second-stage alloy billet: Slow cooling to room temperature in a resistance furnace at 700℃.

[0083] S4. Slow cooling and surface treatment of the third-stage alloy billet: Slow cooling to room temperature in a resistance furnace at 700℃.

[0084] Comparative Example 1: This comparative example provides a method for preparing Ti-Al-Sn titanium alloy rods, including the following steps: S1. Pretreatment stage: Select an alloy ingot with a specification of Φ300×800 mm. The elemental composition of the alloy ingot by mass fraction is: Sn 4%, Al 6.5%, W 2.0%, Si 0.4%, C 0.05%, with the balance being Ti and unavoidable impurities. An anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy ingot. It is preheated to 900℃ and held for 6 hours, then heated to 1100℃ and held for 8 hours. After being taken out of the furnace and shaped into a square billet with a height-to-diameter ratio of 2, it is returned to the furnace and heated to 1100℃ for later use. S2. First-stage upsetting and forging: The square billet undergoes two upsetting processes (one heat and two passes) to obtain the first-stage alloy billet. The first heat is at 1150℃ and held for 8 hours. After exiting the furnace, it undergoes two further upsetting processes with progressively lower temperatures: the first at 1150℃ and the second at 1120℃, with a 4-hour hot-material reheating period in between. The final forging temperature is not lower than 1050℃. The upsetting deformation in both processes is 45%, and the deformation rate is 1.0 s. -1 The total forging ratio is 3; The upsetting and drawing anvil temperature is 450℃, and the upper and lower end faces of the billet are covered with an asbestos layer with a thickness of 25 mm (the subsequent second-stage upsetting and drawing forging and the third-stage upsetting and drawing forging maintain this condition, which will not be repeated here).

[0085] The first-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the first-stage alloy billet is polished and cleaned. The specific method of polishing and cleaning is a conventional technique in this field, so it will not be described in detail.

[0086] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the first-stage alloy billet, and it is heated to 900℃ and held for 6 hours.

[0087] S3. Second-stage upsetting and forging: The first-stage alloy billet is upset four times in four stages (one heat, four cycles) to obtain the second-stage alloy billet; the first heat is heated to 950℃ and held for 6 hours; the deformation rate is 0.1 s⁻¹. -1 The total forging ratio is 5; the first upsetting deformation is 25%, the second upsetting deformation is 30%, the third upsetting deformation is 35%, and the fourth upsetting deformation is 40%, with hot material being recycled back into the furnace for 2 hours in between. A 90° reversing upsetting process is performed after the second upsetting; the final forging temperature is not lower than 1000℃.

[0088] The second-stage alloy billet undergoes slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the second-stage alloy billet is polished and cleaned.

[0089] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the second stage, and the billet is heated to 900℃ and held for 4 hours.

[0090] S4. Third-stage upsetting and drawing forging: The second-stage alloy billet undergoes four upsetting and drawing cycles (one heat, four passes) to obtain the third-stage alloy billet. The first heat cycle is heated to 930℃ and held for 6 hours. After removal from the furnace, it undergoes one upsetting and one drawing cycle, with an upsetting deformation of 35% and a deformation rate of 0.05 s⁻¹. -1 After forging, the hot material is returned to the furnace and kept warm for 2 hours. The forging process is repeated four times, with a total forging ratio of 2. Among them, after the second upsetting, a 90° reversing upsetting is performed. The final forging temperature is not lower than 980℃.

[0091] The third-stage alloy billet is subjected to slow cooling and surface treatment: it is slowly cooled to room temperature in a resistance furnace at 600℃, and the surface of the third-stage alloy billet is polished and cleaned.

[0092] Subsequently, an anti-oxidation coating (silicate glass coating, coating thickness 35um) is formed on the surface of the alloy billet in the third stage, and the temperature is heated to 900℃ and held for 4 hours.

[0093] S5. Final forging stage: The alloy billet of the third stage is heated to 920℃ and held for 4 hours. After being taken out of the furnace, it is shaped and drawn in an octagonal direction along the length of the billet. Then it is rolled into a bar billet with a size of Φ300×760mm. The bar billet is then optimized by heat treatment (the bar billet is heated to 900℃, held for 4 hours, and air-cooled to room temperature) to obtain the target titanium alloy bar.

[0094] According to GB / T 5168-2020 "Test Methods for High and Low Magnification Microstructure of Titanium and Titanium Alloys", the microstructure of titanium alloy bar samples was characterized after grinding, polishing, and etching. Figure 4 As shown, the characterization results indicate that the alloy has a dual-state structure, with an average primary α phase size of 18 μm and a primary β grain size of 45 μm. The structure is uniform and defect-free.

[0095] According to GB / T 228.1-2021 "Metallic Materials - Tensile Testing", the tensile properties of titanium alloy bar specimens were tested. The test data are shown in Table 4. The results show that the room temperature tensile strength is not less than 1045 MPa and the elongation is not less than 11%; the high temperature tensile strength at 700℃ is not less than 430 MPa and the elongation is not less than 32%.

[0096] Table 4 Tensile property test data for Comparative Example 1

[0097] The above examples demonstrate that within the composition range of the ordered phase-strengthened Ti-Al-Sn alloy (Al: 5~8 wt.%, Sn: 10-15 wt.%, adjusting elements 1-5%), after forging and heat treatment, the alloy exhibits a room temperature strength of not less than 1190 MPa and an elongation of not less than 9%; a high-temperature strength at 700℃ of not less than 650 MPa and an elongation of not less than 26%. Compared with the performance in the comparative examples in Table 4, the reduced Sn content in the comparative examples may have resulted in the absence of ordered phase formation, leading to significantly lower room temperature and high-temperature performance of the obtained bars compared to the implementation examples. The alloy designed in this invention exhibits significant advantages in both thermal strength and thermal stability; and compared to the novel Ti-Al-Sn alloy, the strength-plasticity balance and hot working performance of the above alloy are significantly optimized. This alloy is expected to partially replace traditional nickel-based alloys in aerospace applications and has great application potential in high-temperature stator structural components.

[0098] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects.

[0099] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention fall within the scope of protection of this invention.

Claims

1. A method for preparing Ti-Al-Sn titanium alloy rods with ordered phase reinforcement, characterized in that, Includes the following steps: S1. Heat the alloy ingot and shape it into a square billet; S2. The square billet is uptaken twice (1 heat, 2 cycles) to obtain the first stage alloy billet; S3. The first-stage alloy billet is subjected to four gradient incremental upsetting processes (one heat, four passes) to obtain the second-stage alloy billet. S4. The second-stage alloy billet is uptaken and drawn four times in one heat and four times in four cycles to obtain the third-stage alloy billet. S5. After heating the alloy billet in the third stage, it is successively shaped, drawn, and rolled to form a billet. The heat treatment of the billet is optimized to obtain Ti-Al-Sn titanium alloy rods.

2. The method for preparing the ordered phase-strengthened Ti-Al-Sn titanium alloy rod according to claim 1, characterized in that, In step S1, the heating temperature is 1150-1250℃, and the temperature is maintained for 8-10 hours. The height-to-diameter ratio of the square billet is 1.5-3; The elemental composition of the alloy ingot, by mass fraction, is as follows: Sn 10-15%, Al 5-8%, adjusting elements 1-5%, and the balance Ti; wherein, the adjusting elements include W, Si and C.

3. The method for preparing the ordered phase-strengthened Ti-Al-Sn titanium alloy rod according to claim 1, characterized in that, In S2, the heating temperature for the first heating cycle is 1150℃-1250℃, and the holding temperature is 8-10 h. The upsetting temperature is gradually decreased, the upsetting deformation is 45-55%, and the deformation rate is 0.5-1 s. -1 The total forging ratio is 2-4; The gradual reduction of upsetting temperature includes: the first upsetting temperature in the first stage of upsetting forging is 1150-1250℃, the second upsetting temperature in the first stage of upsetting forging is 1200-1250℃, hot material is recycled back into the furnace for 2-4 hours in between, and the final forging temperature is not lower than 1050℃.

4. The method for preparing the ordered phase-strengthened Ti-Al-Sn titanium alloy rod according to claim 1, characterized in that, In S3, the heating temperature for the first heating cycle is 1050-1080℃, and the holding time is 6-8 h. The upsetting deformation rate is 0.1-0.15 s. -1 The total forging ratio is 5-8.

5. The method for preparing Ti-Al-Sn titanium alloy rods with ordered phase reinforcement according to claim 1, characterized in that, In S3, the gradient incremental upsetting includes: the first upsetting deformation is 25-30%, the second upsetting deformation is 30-35%, the third upsetting deformation is 35-40%, and the fourth upsetting deformation is 40-45%.

6. The method for preparing the ordered phase-strengthened Ti-Al-Sn titanium alloy rod according to claim 1, characterized in that, In step S4, the heating temperature for the first heating cycle is 1030-1050℃, and the holding time is 4-6 hours. The upsetting deformation is 35-45%, and the deformation rate is 0.01-0.1 s. -1 The total forging ratio is 2-5.

7. The method for preparing Ti-Al-Sn titanium alloy rods with ordered phase reinforcement according to claim 1, characterized in that, After S2, S3 and S4, slow cooling treatment and surface treatment are also included respectively; The slow cooling treatment involves slow cooling from 500-700℃ to room temperature; the surface treatment involves polishing and cleaning.

8. The method for preparing the ordered phase-strengthened Ti-Al-Sn titanium alloy rod according to claim 1, characterized in that, In step S5, the heating temperature is 1020-1030℃, and the temperature is maintained for 4-6 hours.

9. The method for preparing the ordered phase-strengthened Ti-Al-Sn titanium alloy rod according to claim 1, characterized in that, The Ti-Al-Sn titanium alloy rod has a room temperature tensile strength ≥1190 MPa and an elongation ≥8%; a high temperature tensile strength of ≥650 MPa and an elongation ≥26% at 700℃.

10. A Ti-Al-Sn titanium alloy rod with ordered phase reinforcement, characterized in that, The Ti-Al-Sn titanium alloy rod is obtained by the method for preparing ordered phase-strengthened Ti-Al-Sn titanium alloy rods as described in any one of claims 1-9.

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