A type of 1100MPa+120MPa 1 / 2 High-strength, high-damage-tolerant titanium alloys and their preparation methods

Abstract

This invention discloses a 1100MPa+120MPa 1 / 2 This invention relates to a high-strength, high-damage-tolerance titanium alloy and its preparation method, belonging to the field of titanium alloy technology. The invention relates to a high-strength, high-damage-tolerance titanium alloy with a strength of 1100 MPa + 120 MPa. 1 / 2 This invention relates to a high-strength, high-damage-tolerance titanium alloy, comprising, by mass percentage, Ti and the following components: Al 6.0–7.0%, Zr 1.5–2.5%, Mo 3.5–4.5%, Si 0.20–0.35%, and O 0.08–0.16%. Through precise alloy composition design, additive manufacturing, and optimized heat treatment methods (single-phase region short-time solution treatment + double annealing heat treatment), this invention achieves a strength of 1100 MPa + 120 MPa·m. 1 / 2 The combination of high strength and high damage tolerance overcomes the well-known strength-toughness inversion problem in materials science.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy technology, and in particular to a 1100MPa+120MPa alloy. 1 / 2 High-strength, high-damage-tolerant titanium alloys and their preparation methods. Background Technology

[0002] Titanium alloys, as important metallic structural materials, possess advantages such as high specific strength, good thermal strength, good weldability, and good corrosion resistance, and are widely used in advanced aerospace equipment such as aircraft, engines, and hypersonic vehicles. In particular, titanium alloy materials used in aircraft manufacturing must possess high strength and high damage tolerance (high fracture toughness and low fatigue crack propagation rate) to meet the performance requirements of lightweight, long service life, and high safety in aircraft operations.

[0003] However, titanium alloys prepared using traditional grades and methods suffer from a severe strength-toughness inversion problem. Currently, the main approach to improving damage tolerance is to reduce the content of impurity elements such as oxygen, sacrificing some strength. For example, the Ti-6Al-4V-ELI low-gap titanium alloy (domestic grade TC4-DT) strictly controls the oxygen content to a low level of less than 0.11% (GJB 9577-2018 Specification for Titanium and Titanium Alloy Powders for Additive Manufacturing), achieving a fracture toughness greater than 110 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 (Condition) less than 1×10 -5 While it offers high damage tolerance (mm / cycle), its room temperature tensile strength drops to 810-860 MPa, severely impacting lightweight aircraft design. The high-strength, damage-tolerant TC21 titanium alloy (Ti-6Al-2Sn-3Mo-1Cr-2Zr-2Nb) can increase room temperature tensile strength to 1100 MPa, but its fracture toughness decreases to 70 MPa·m. 1 / 2 To date, there are no engineering applications domestically or internationally that achieve a tensile strength of 1100 MPa and a fracture toughness of 120 MPa·m. 1 / 2 The development of high-strength, high-damage-tolerant titanium alloy materials and preparation technologies with a good balance of strength and toughness has severely limited the development of lightweight and damage-tolerant structural designs for next-generation aircraft. Summary of the Invention

[0004] The purpose of this invention is to provide a 1100MPa+120MPa 1 / 2 This invention relates to a high-strength, high-damage-tolerance titanium alloy and its preparation method, aiming to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention: a 1100MPa+120MPa1 / 2 High-strength, high-damage-tolerant titanium alloy, by mass percentage, comprising Ti and the following components: Al 6.0~7.0%, Zr 1.5~2.5%, Mo 3.5~4.5%, Si 0.20~0.35% and O 0.08~0.16%.

[0006] The second technical solution of the present invention: a pressure of 1100MPa + 120MPa as described above. 1 / 2 A method for preparing high-strength, high-damage-tolerance titanium alloys includes the following steps: Titanium alloy billets were prepared according to the component ratios; The titanium alloy billet was prepared into a titanium alloy component using a directional energy deposition additive manufacturing method. The titanium alloy component was subjected to single-phase short-time solution treatment and double annealing heat treatment in sequence to obtain the 1100MPa+120MPa. 1 / 2 High-strength, high-damage-tolerant titanium alloy.

[0007] Preferably, the method for preparing the titanium alloy billet includes the following steps: The raw materials are mixed according to the component ratio, and titanium alloy ingots are prepared by vacuum consumable arc melting. After forging, titanium alloy billets are prepared by gas atomization or drawing deformation.

[0008] Preferably, the vacuum self-consuming arc melting is performed ≥ 2 times; The titanium alloy billet prepared by the gas atomization method is a spherical titanium alloy powder with a particle size of 53~250μm; The titanium alloy billet prepared by the drawing deformation method is a titanium alloy wire with a diameter of 1.0~2.0 mm.

[0009] More preferably, the gas atomization method includes commonly used gas atomization methods such as electrode induction melting gas atomization (EIGA) or plasma rotating electrode gas atomization (PREP).

[0010] More preferably, the titanium alloy wire can be prepared using conventional drawing deformation methods.

[0011] Preferably, when the titanium alloy billet is titanium alloy spherical powder, the directional energy deposition additive manufacturing method used is the powder feeding laser directional energy deposition additive manufacturing method; When the titanium alloy billet is titanium alloy wire, the directional energy deposition additive manufacturing method used is either wire-feed laser directional energy deposition additive manufacturing method or wire-feed arc directional energy deposition additive manufacturing method.

[0012] Preferably, the parameters of the powder-feeding laser directional energy deposition additive manufacturing method include: spot diameter 3~10mm, laser power 2~10kW, scanning rate 500~1500mm / min, powder feeding rate 500~2000g / h, overlap rate 30~60%, single-layer height increase 0.3~1.0mm, argon protective atmosphere, and oxygen content <100ppm.

[0013] Preferably, the parameters of the laser-directed energy deposition additive manufacturing method include: spot diameter 3~8mm, laser power 1~6kW, scanning rate 300~1000mm / min, wire feeding speed 1000~3000mm / min, wire diameter φ1.0~2.0mm, overlap rate 30~45%, single-layer height increase 0.8~2.0mm, argon protective atmosphere, and oxygen content <100ppm.

[0014] Preferably, the parameters of the wire-feeding arc-directed energy deposition additive manufacturing method include: welding current 120~220A, arc voltage 20~35V, arc power 2~8kW, scanning speed 100~500mm / min, wire feed speed 1200~3000mm / min, wire diameter φ1.0~2.0mm, overlap rate 30~45%, single-layer height increase 1.0~3.0mm, argon protective atmosphere, and oxygen content <100ppm.

[0015] Preferably, the short-time solid solution treatment in the single-phase region includes: holding at a temperature 10~30°C above Tβ for 5~15 minutes, followed by water quenching.

[0016] If the short-term solid solution time in the single-phase region is less than 5 minutes, the α phase cannot be completely dissolved, which affects the improvement of the aspect ratio of the primary α phase. If the time is longer than 15 minutes, the original β grains tend to grow rapidly, leading to a decrease in mechanical properties.

[0017] The dual annealing heat treatment includes a first-stage high-temperature annealing heat treatment and a second-stage low-temperature annealing heat treatment; the first-stage high-temperature annealing heat treatment includes: holding at 10~40℃ below Tβ temperature for 1~2 hours and air cooling; the second-stage low-temperature annealing heat treatment includes: holding at 500~600℃ for 2~6 hours and air cooling.

[0018] The third technical solution of the present invention: a method for applying the above-mentioned 1100MPa+120MPa 1 / 2 Applications of high-strength, high-damage-tolerant titanium alloys in the aerospace field.

[0019] The high-strength, high-damage-tolerant titanium alloy prepared by this invention is a special dual-state structure composed of lamellar primary α phase + β transformation structure. The average aspect ratio of the primary α phase is greater than 10, and the volume fraction is 15~50%.

[0020] The high-strength, high-damage-tolerant titanium alloy prepared by this invention exhibits superior strength, fracture toughness, and crack propagation performance compared to traditional damage-tolerant titanium alloys such as TC4-DT and TC21. Its tensile strength exceeds 1100 MPa, elongation after fracture exceeds 10%, and fracture toughness exceeds 120 MPa·m. 1 / 2 Crack propagation rate (R=0.1ΔK=11MPa·m) 1 / 2 (Condition) less than 1.00 × 10 -5 mm / cycle, overall performance matching.

[0021] The "single-phase region short-time solution treatment + double annealing heat treatment" method adopted in this invention, compared with the traditional double annealing heat treatment, can ensure complete solid solution of the α phase and prevent β grain growth by holding the single-phase region for a short time (α phase residue is likely to occur if the time is less than 5 minutes, and β grain growth is likely to occur if the time is more than 15 minutes). Subsequently, water quenching and rapid cooling form a slender α' phase. In the subsequent double annealing heat treatment, the aspect ratio of the lamellar primary α phase can be further improved, effectively hindering the rapid crack propagation, thereby significantly improving the damage tolerance performance.

[0022] The present invention discloses the following technical effects: (1) Compared with the existing TC4-DT damage-tolerant titanium alloy, the high-strength and high-damage-tolerant titanium alloy of the present invention does not need to control the oxygen element below 0.11% (i.e., it does not need to purchase pure Ti raw materials with higher purity and price, and does not need to precisely control the oxygen content), which can reduce the cost of raw materials.

[0023] (2) This invention achieves 1100MPa + 120MPa·m through precise alloy composition design, additive manufacturing, and optimized heat treatment methods (single-phase region short-time solid solution + double annealing heat treatment). 1 / 2 The combination of high strength and high damage tolerance overcomes the well-known strength-toughness inversion problem in materials science, representing a significant technological advancement.

[0024] (3) The preparation method of this invention is fully applicable to laser, arc, and electron beam directed energy deposition additive manufacturing methods, and is especially suitable for the manufacture of large and complex titanium alloy components. Through directed energy deposition additive manufacturing and optimized heat treatment methods, components with tensile strength greater than 1100 MPa, elongation after fracture greater than 10%, and fracture toughness greater than 120 MPa·m were prepared. 1 / 2 Crack propagation rate (R=0.1ΔK=11MPa) 1 / 2 (Condition) less than 1.00 × 10 -5 The titanium alloy with a capacity of mm / cycle achieves a comprehensive performance match, and its strength and damage tolerance properties are superior to existing titanium alloys. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the preparation process of the high-strength, high-damage-tolerance titanium alloy of the present invention; Figure 2 This is a typical low-magnification microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Example 1 of the present invention; Figure 3 Typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Example 1 of this invention; Figure 4 Typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Example 2 of this invention; Figure 5 Typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Example 3 of this invention; Figure 6 Typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Example 4 of this invention; Figure 7 This is a typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Comparative Example 1 of this invention; Figure 8 This is a typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Comparative Example 2 of this invention; Figure 9 This is a typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Comparative Example 3 of this invention. Figure 10 This is a typical microstructure of the high-strength, high-damage-tolerance titanium alloy prepared in Comparative Example 4 of this invention. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0030] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0033] In a first aspect, the present invention provides a 1100MPa+120MPa·m 1 / 2 High-strength, high-damage-tolerant titanium alloy, by mass percentage, comprising Ti and the following components: Al 6.0~7.0%, Zr 1.5~2.5%, Mo 3.5~4.5%, Si 0.20~0.35% and O 0.08~0.16%.

[0034] In a second aspect, the present invention provides a pressure of 1100MPa + 120MPa as described above. 1 / 2 A method for preparing high-strength, high-damage-tolerance titanium alloys includes the following steps: Titanium alloy billets were prepared according to the component ratios; Titanium alloy blanks are fabricated into titanium alloy components using directional energy deposition additive manufacturing. The titanium alloy component was subjected to single-phase short-time solution treatment and double annealing heat treatment in sequence to obtain a strength of 1100 MPa + 120 MPa·m. 1 / 2 High-strength, high-damage-tolerant titanium alloy.

[0035] Preferably, the method for preparing titanium alloy billets includes the following steps: The raw materials are mixed according to the component ratio and titanium alloy ingots are prepared by vacuum consumable arc melting. After forging, titanium alloy billets are prepared by gas atomization or drawing deformation.

[0036] Preferably, the vacuum self-consuming arc melting is performed ≥ 2 times; The titanium alloy billet prepared by gas atomization is a spherical titanium alloy powder with a particle size of 53~250μm; The titanium alloy billet prepared by the drawing deformation method is a titanium alloy wire with a diameter of 1.0~2.0 mm.

[0037] More preferably, the gas atomization method includes commonly used gas atomization methods such as electrode induction melting gas atomization (EIGA) or plasma rotating electrode gas atomization (PREP).

[0038] More preferably, titanium alloy wire can be prepared using conventional drawing deformation methods.

[0039] Preferably, when the titanium alloy billet is titanium alloy spherical powder, the directional energy deposition additive manufacturing method used is the powder feeding laser directional energy deposition additive manufacturing method; When the titanium alloy billet is titanium alloy wire, the directional energy deposition additive manufacturing method used is either wire-feed laser directional energy deposition additive manufacturing method or wire-feed arc directional energy deposition additive manufacturing method.

[0040] Preferred parameters for the powder-feeding laser-directed energy deposition additive manufacturing method include: spot diameter 3~10mm, laser power 2~10kW, scanning rate 500~1500mm / min, powder feeding rate 500~2000g / h, overlap rate 30~60%, single-layer height increase 0.3~1.0mm, argon protective atmosphere, and oxygen content <100ppm.

[0041] Preferred parameters for the wire-feeding laser-directed energy deposition additive manufacturing method include: spot diameter 3~8mm, laser power 1~6kW, scanning rate 300~1000mm / min, wire feeding speed 1000~3000mm / min, wire diameter φ1.0~2.0mm, overlap rate 30~45%, single-layer height increase 0.8~2.0mm, argon protective atmosphere, and oxygen content <100ppm.

[0042] Preferably, the parameters of the wire-feeding arc directional energy deposition additive manufacturing method include: welding current 120~220A, arc voltage 20~35V, arc power 2~8kW, scanning speed 100~500mm / min, wire feed speed 1200~3000mm / min, wire diameter φ1.0~2.0mm, overlap rate 30~45%, single-layer height increase 1.0~3.0mm, argon protective atmosphere, and oxygen content <100ppm.

[0043] Preferably, the single-phase region short-time solution treatment (i.e., single-phase region pretreatment) includes: holding at 10~30℃ above Tβ temperature for 5~15 min, followed by water quenching; The double annealing heat treatment includes a first-stage high-temperature annealing heat treatment and a second-stage low-temperature annealing heat treatment. The first-stage high-temperature annealing heat treatment includes holding at 10~40℃ below Tβ temperature for 1~2 hours and then air cooling. The second-stage low-temperature annealing heat treatment includes holding at 500~600℃ for 2~6 hours and then air cooling.

[0044] In a third aspect, the present invention provides a solution with the aforementioned 1100MPa + 120MPa·m 1 / 2 Applications of high-strength, high-damage-tolerant titanium alloys in the aerospace field.

[0045] A schematic diagram of the preparation process for high-strength, high-damage-tolerance titanium alloys is shown below. Figure 1 .

[0046] Example 1 A type of 1100MPa+120MPa·m 1 / 2 Preparation method of high-strength, high-damage-tolerant titanium alloy: (1) High-strength, high-damage-tolerance titanium alloy, with the following composition by mass percentage: Al 6.5%, Zr 2.0%, Mo 4.0%, Si 0.25%, O 0.13%, with the balance being Ti and unavoidable impurities.

[0047] (2) Weigh out powder or granular raw materials such as sponge titanium, sponge zirconium, aluminum molybdenum, aluminum silicon, and aluminum granules according to the component ratio, mix them, and prepare titanium alloy ingots by vacuum self-consuming electric arc melting (melting twice). Forge the titanium alloy ingots to obtain titanium alloy bars with a size of φ60mm×500mm.

[0048] (3) Titanium alloy spherical powder was prepared by plasma rotating electrode atomization (PREP) and the particle size distribution after sieving was between 53 and 250 μm.

[0049] (4) Using the titanium alloy spherical powder prepared in step (3) as raw material, titanium alloy test pieces (i.e. titanium alloy components) are prepared by powder feeding laser directional energy deposition additive manufacturing method. The forming size is 130×70×45mm thick plate test pieces. The process parameters of the powder feeding laser directional energy deposition additive manufacturing method are: spot diameter 6mm, laser power 6kW, scanning rate 1000mm / min, powder feeding rate 1200g / h, overlap rate 50%, single layer height increase 0.7mm, argon protective atmosphere, oxygen content <100ppm.

[0050] (5) Blocks of different sizes were cut by electrical discharge wire cutting for phase transition point Tβ testing and heat treatment. The phase transition point Tβ was 1010℃.

[0051] (6) Perform short-time solution treatment in the single-phase region (i.e., short-time pretreatment in the single-phase region) on the titanium alloy test piece. The parameters are: heat treatment at 1030℃ for 10 min, followed by water quenching.

[0052] (7) The sample was subjected to double annealing heat treatment. The heat treatment process was as follows: the first stage high temperature annealing heat treatment process parameters were: 980℃ for 1h, air cooling; the second stage low temperature annealing heat treatment process parameters were: 530℃ for 6h, air cooling, to obtain a high strength and high damage tolerance titanium alloy.

[0053] The high-strength, high-damage-tolerance titanium alloy prepared in this embodiment was characterized in terms of microstructure and properties according to relevant national standards. The microstructure characterization was performed according to GB / T 5168-2020, the room temperature tensile test was performed according to GB / T 228.1-2021, the room temperature fracture toughness test was performed according to GB / T 4161-2007, and the fatigue crack propagation rate test was performed according to GB / T 6398-2017.

[0054] The typical low-magnification microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment is shown below. Figure 2 .

[0055] from Figure 2 As can be seen from the data, the high-strength, high-damage-tolerance titanium alloy prepared in this embodiment has a columnar-equiaxed mixed structure.

[0056] The typical microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment is shown in the figure. Figure 3 .

[0057] from Figure 3 As can be seen from the data, the high-strength, high-damage-tolerance titanium alloy prepared in this embodiment is a dual-state structure consisting of lamellar primary α phase and ultrafine β transformation structure. Its primary α phase content (volume fraction) is about 32%, and its aspect ratio is 14.

[0058] The mechanical property test results of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment are shown in Table 1.

[0059] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment has a room-temperature tensile strength of 1139 MPa, a yield strength of 962 MPa, an elongation after fracture of 12.5%, and a fracture toughness of 124 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 0.85 × 10 -5 mm / cycle.

[0060] Example 2 A type of 1100MPa+120MPa·m 1 / 2 Preparation method of high-strength, high-damage-tolerant titanium alloy: (1) High-strength, high-damage-tolerance titanium alloy, with the following composition by mass percentage: Al 6.5%, Zr 2.0%, Mo 4.0%, Si 0.25%, O 0.13%, with the balance being Ti and unavoidable impurities.

[0061] (2) Weigh out powder or granular raw materials such as sponge titanium, sponge zirconium, aluminum molybdenum, aluminum silicon, and aluminum granules according to the component ratio, mix them, and prepare titanium alloy ingots by vacuum self-consuming electric arc melting (melting twice). Forge the titanium alloy ingots to obtain titanium alloy bars with a size of φ60mm×500mm.

[0062] (3) Titanium alloy wire with a diameter of 1.2 mm was prepared by conventional drawing deformation method.

[0063] (4) Using the titanium alloy wire prepared in step (3) as raw material, titanium alloy test pieces (i.e. titanium alloy components) are prepared by wire feeding laser directional energy deposition additive manufacturing method. The forming size is 130×70×45mm thick plate test pieces. The process parameters of the wire feeding laser directional energy deposition additive manufacturing method are: spot diameter 4mm, laser power 3kW, scanning rate 600mm / min, wire feeding speed 2000mm / min, wire diameter φ1.2mm, overlap rate 40%, single layer height increase 1.3mm, argon protective atmosphere, oxygen content <100ppm.

[0064] (5) Blocks of different sizes were cut by electrical discharge wire cutting for phase transition point Tβ testing and heat treatment. The phase transition point Tβ was 1010℃.

[0065] (6) Same as Example 1.

[0066] (7) Same as Example 1.

[0067] The typical microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment is shown in the figure. Figure 4 .

[0068] from Figure 4 As can be seen from the data, the high-strength, high-damage-tolerance titanium alloy prepared in this embodiment is a dual-state structure consisting of lamellar primary α phase and ultrafine β transformation structure, with a primary α phase content (volume fraction) of approximately 28% and an aspect ratio of 12.

[0069] The mechanical property test results of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment are shown in Table 1.

[0070] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment has a room-temperature tensile strength of 1122 MPa, a yield strength of 946 MPa, an elongation after fracture of 13.0%, and a fracture toughness of 126 MPa·m. 1 / 2Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 0.90 × 10 -5 mm / cycle.

[0071] Example 3 A type of 1100MPa+120MPa·m 1 / 2 Preparation method of high-strength, high-damage-tolerant titanium alloy: (1) High-strength, high-damage-tolerance titanium alloy, with the following composition by mass percentage: Al 6.5%, Zr 2.0%, Mo 4.0%, Si 0.25%, O 0.13%, with the balance being Ti and unavoidable impurities.

[0072] (2) Weigh out powder or granular raw materials such as sponge titanium, sponge zirconium, aluminum molybdenum, aluminum silicon, and aluminum granules according to the component ratio, mix them, and prepare titanium alloy ingots by vacuum self-consuming electric arc melting (melting twice). Forge the titanium alloy ingots to obtain titanium alloy bars with a size of φ60mm×500mm.

[0073] (3) Titanium alloy wire with a diameter of 1.2 mm was prepared by conventional drawing deformation method.

[0074] (4) Using the titanium alloy wire prepared in step (3) as raw material, titanium alloy test pieces (i.e. titanium alloy components) are prepared by wire feeding arc directional energy deposition additive manufacturing method. The forming size is 130×70×45mm thick plate test pieces. The process parameters of the wire feeding arc directional energy deposition additive manufacturing method are: welding current 160A, arc voltage 25V, arc power 4kW, scanning speed 400mm / min, wire feeding speed 2000mm / min, wire diameter φ1.2mm, overlap rate 35%, single layer height increase 1.6mm, argon protective atmosphere, oxygen content <100ppm.

[0075] (5) Blocks of different sizes were cut by electrical discharge wire cutting for phase transition point Tβ testing and heat treatment. The phase transition point Tβ was 1010℃.

[0076] (6) Same as Example 1.

[0077] (7) Same as Example 1.

[0078] The typical microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment is shown in the figure. Figure 5 .

[0079] from Figure 5 As can be seen from the data, the high-strength, high-damage-tolerance titanium alloy prepared in this embodiment is a dual-state structure consisting of lamellar primary α phase and ultrafine β transformation structure, with a primary α phase content (volume fraction) of approximately 35% and an aspect ratio of 15.

[0080] The mechanical property test results of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment are shown in Table 1.

[0081] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment has a room-temperature tensile strength of 1119 MPa, a yield strength of 938 MPa, an elongation after fracture of 13.5%, and a fracture toughness of 128 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 0.75 × 10 -5 mm / cycle.

[0082] Example 4 A type of 1100MPa+120MPa·m 1 / 2 Preparation method of high-strength, high-damage-tolerant titanium alloy: (1) High-strength, high-damage-tolerance titanium alloy, with the following composition by mass percentage: Al 6.7%, Zr 2.4%, Mo 4.4%, Si 0.25%, O 0.13%, with the balance being Ti and unavoidable impurities.

[0083] (2)~(7) are the same as in Example 1.

[0084] The typical microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment is shown in the figure. Figure 6 .

[0085] from Figure 6 As can be seen from the data, the high-strength, high-damage-tolerance titanium alloy prepared in this embodiment is a dual-state structure consisting of lamellar primary α phase and ultrafine β transformation structure. Its primary α phase content (volume fraction) is about 34%, and its aspect ratio is 15.

[0086] The mechanical property test results of the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment are shown in Table 1.

[0087] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment has a room-temperature tensile strength of 1167 MPa, a yield strength of 989 MPa, an elongation after fracture of 10.5%, and a fracture toughness of 121 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 0.97 × 10 -5 mm / cycle. It can be seen that the contents of the two main alloying elements, Zr and Mo, are slightly increased, resulting in a slight increase in strength, while the plasticity and damage tolerance properties do not decrease significantly and remain at a high level.

[0088] Comparative Example 1 A method for preparing a high-strength, high-damage-tolerance titanium alloy, wherein the contents of the two main alloying elements, Zr and Mo, are lower than those specified in this invention: (1) High-strength, high-damage-tolerance titanium alloy, with the following composition by mass percentage: Al 6.5%, Zr 1.3%, Mo 3.3%, Si 0.25%, O 0.13%, with the balance being Ti and unavoidable impurities.

[0089] (2)~(7) are the same as in Example 1.

[0090] The typical microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example is shown below. Figure 7 .

[0091] from Figure 7 As can be seen from the data, the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example has a dual-state structure consisting of lamellar primary α phase and ultrafine β-transformation microstructure. The primary α phase content (volume fraction) is approximately 34%, and the aspect ratio is 11. The microstructure is not significantly different from that of Example 1 of this invention.

[0092] The mechanical property test results of the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example are shown in Table 1.

[0093] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example has a room-temperature tensile strength of 1069 MPa, a yield strength of 924 MPa, an elongation after fracture of 13.5%, and a fracture toughness of 122 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 0.92 × 10 -5 mm / cycle. It is evident that when the contents of the two main alloying elements, Zr and Mo, are reduced and fall below the range of this invention, the solid solution strengthening effect weakens, and the strength decreases significantly, falling below the 1100 MPa level. Combining Examples 1, 4, and Comparative Example 1, it can be seen that selecting the ranges of 1.5~2.5% and 3.5~4.5% for Zr and Mo, the two main alloying elements, is necessary to ensure 1100 MPa + 120 MPa·m. 1 / 2 Key factors for achieving high strength and high damage tolerance performance levels.

[0094] Comparative Example 2 A method for preparing a high-strength, high-damage-tolerance titanium alloy (using a traditional ingot casting + forging deformation process): (1) High-strength, high-damage-tolerance titanium alloy, with the following composition by mass percentage: Al 6.5%, Zr 2.0%, Mo 4.0%, Si 0.25%, O 0.13%, with the balance being Ti and unavoidable impurities.

[0095] (2) Weigh out powder or granular raw materials such as sponge titanium, sponge zirconium, aluminum molybdenum, aluminum silicon, and aluminum granules according to the component ratio, mix them, and prepare titanium alloy ingots by vacuum self-consuming electric arc melting (melting twice). Forge the titanium alloy ingots to obtain titanium alloy bars with a size of φ60mm×500mm.

[0096] (3) The titanium alloy bar was subjected to conventional two-phase forging at a forging temperature of 950℃ and a total forging deformation of 200% to obtain a titanium alloy test piece.

[0097] (4) Blocks of different sizes were cut by electrical discharge wire cutting for phase transition point Tβ testing and heat treatment. The phase transition point Tβ was 1010℃.

[0098] (5) The titanium alloy test piece was subjected to double annealing heat treatment. The heat treatment process was as follows: the first stage high temperature annealing heat treatment process parameters were: 980℃ for 1h, air cooling; the second stage low temperature annealing heat treatment process parameters were: 530℃ for 6h, air cooling, to obtain a high-strength and high-damage-tolerance titanium alloy.

[0099] The typical microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example is shown below. Figure 8 .

[0100] from Figure 8 As can be seen from the above, the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example has a dual-state structure consisting of a traditional equiaxed primary α phase and an ultrafine β transformation structure. The content (volume fraction) of the equiaxed primary α phase is about 35%, and the aspect ratio is 1.2.

[0101] The mechanical property test results of the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example are shown in Table 1.

[0102] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example has a room-temperature tensile strength of 1136 MPa, a yield strength of 1020 MPa, an elongation after fracture of 13.0%, and a fracture toughness of 88 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 2.40 × 10 -5 mm / cycle. It can be seen that for titanium alloys of the same composition, the room temperature tensile properties prepared by the traditional ingot casting + deformation process are comparable to those prepared by the additive manufacturing process, but the fracture toughness is significantly reduced, the crack propagation rate is significantly increased, and the damage tolerance is significantly decreased.

[0103] Comparative Example 3 Same as Example 1, except that step (6) is not performed.

[0104] The typical microstructure of the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example is shown below. Figure 9 .

[0105] from Figure 9 As can be seen from the above, the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example has a dual-state structure consisting of lamellar primary α phase and ultrafine β transformation structure. Its primary α phase content (volume fraction) is about 38%, and its aspect ratio is 7.

[0106] The mechanical property test results of the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example are shown in Table 1.

[0107] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this comparative example has a room-temperature tensile strength of 1112 MPa, a yield strength of 944 MPa, an elongation after fracture of 12.2%, and a fracture toughness of 109 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 1.35 × 10 -5 mm / cycle. It is evident that without short-term pretreatment in the single-phase region, the aspect ratio of the primary α phase in the prepared sample is significantly reduced, resulting in decreased fracture toughness and fatigue crack propagation performance.

[0108] Comparative Example 4 TC4 titanium alloy: (1)~(3) Taking TC4 duplex titanium alloy, which is most widely used in engineering, as the object, spherical titanium alloy powder prepared by PREP is used as the raw material, and the powder particle size is distributed between 53~250μm.

[0109] (4)~(7) Same as Example 1.

[0110] The typical microstructure of the TC4 titanium alloy prepared in this comparative example is shown in the figure. Figure 10 .

[0111] from Figure 10 As can be seen from the data, the TC4 titanium alloy prepared in this embodiment has a dual-state structure consisting of lamellar primary α phase + β transformation structure, with a primary α phase content (volume fraction) of approximately 26% and an aspect ratio of 11.

[0112] The mechanical properties of the TC4 titanium alloy prepared in this embodiment are shown in Table 1.

[0113] As shown in Table 1, the high-strength, high-damage-tolerant titanium alloy prepared in this embodiment has a room-temperature tensile strength of 920 MPa, a yield strength of 840 MPa, an elongation after fracture of 17.0%, and a fracture toughness of 110 MPa·m. 1 / 2 Crack propagation rate (R=0.1 and ΔK=11MPa·m) 1 / 2 The condition is 1.25 × 10 -5mm / cycle. It is evident that mature titanium alloy grades such as TC4 cannot achieve the excellent strength and damage tolerance performance match using the preparation method of this invention directly. This indicates that the technical effect of this invention requires the combined effect of alloy composition, additive manufacturing process, and heat treatment to achieve 1100MPa + 120MPa·m. 1 / 2 High strength and high damage tolerance performance level.

[0114] Table 1 Mechanical properties of titanium alloys The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A type of 1100MPa+120MPa 1 / 2 High-strength, high-damage-tolerant titanium alloy, characterized in that, By mass percentage, it includes Ti and the following components: Al 6.0~7.0%, Zr 1.5~2.5%, Mo 3.5~4.5%, Si 0.20~0.35% and O 0.08~0.16%.

2. The 1100MPa+120MPa as described in claim 1 1 / 2 A method for preparing high-strength, high-damage-tolerance titanium alloys, characterized in that, Includes the following steps: Titanium alloy billets were prepared according to the component ratios; The titanium alloy billet was prepared into a titanium alloy component using a directional energy deposition additive manufacturing method. The titanium alloy component was subjected to single-phase short-time solution treatment and double annealing heat treatment in sequence to obtain the 1100MPa+120MPa. 1 / 2 High-strength, high-damage-tolerant titanium alloy.

3. The preparation method according to claim 2, characterized in that, The method for preparing the titanium alloy billet includes the following steps: The raw materials are mixed according to the component ratio, and titanium alloy ingots are prepared by vacuum consumable arc melting. After forging, titanium alloy billets are prepared by gas atomization or drawing deformation.

4. The preparation method according to claim 3, characterized in that, The vacuum self-consuming arc melting process is repeated ≥ 2 times; And / or, the titanium alloy billet prepared by the gas atomization method is a titanium alloy spherical powder with a particle size of 53~250μm; And / or, the titanium alloy billet prepared by the drawing deformation method is a titanium alloy wire with a diameter of 1.0~2.0 mm.

5. The preparation method according to claim 4, characterized in that, When the titanium alloy billet is titanium alloy spherical powder, the directional energy deposition additive manufacturing method used is the powder feeding laser directional energy deposition additive manufacturing method. When the titanium alloy billet is titanium alloy wire, the directional energy deposition additive manufacturing method used is either wire-feed laser directional energy deposition additive manufacturing method or wire-feed arc directional energy deposition additive manufacturing method.

6. The preparation method according to claim 5, characterized in that, The parameters of the powder-feeding laser-directed energy deposition additive manufacturing method include: spot diameter 3~10mm, laser power 2~10kW, scanning rate 500~1500mm / min, powder feeding rate 500~2000g / h, overlap rate 30~60%, single-layer height increase 0.3~1.0mm, argon protective atmosphere, and oxygen content <100ppm.

7. The preparation method according to claim 5, characterized in that, The parameters of the laser-directed energy deposition additive manufacturing method include: spot diameter 3~8mm, laser power 1~6kW, scanning rate 300~1000mm / min, wire feeding speed 1000~3000mm / min, wire diameter φ1.0~2.0mm, overlap rate 30~45%, single-layer height increase 0.8~2.0mm, argon protective atmosphere, and oxygen content <100ppm.

8. The preparation method according to claim 5, characterized in that, The parameters of the wire-feeding arc directional energy deposition additive manufacturing method include: welding current 120~220A, arc voltage 20~35V, arc power 2~8kW, scanning speed 100~500mm / min, wire feed speed 1200~3000mm / min, wire diameter φ1.0~2.0mm, overlap rate 30~45%, single-layer height increase 1.0~3.0mm, argon protective atmosphere, and oxygen content <100ppm.

9. The preparation method according to claim 2, characterized in that, The single-phase region short-time solid solution includes: holding at 10~30℃ above Tβ temperature for 5~15 min, followed by water quenching; And / or, the dual annealing heat treatment includes a first-stage high-temperature annealing heat treatment and a second-stage low-temperature annealing heat treatment; the first-stage high-temperature annealing heat treatment includes: holding at 10~40℃ below Tβ temperature for 1~2h and air cooling; the second-stage low-temperature annealing heat treatment includes: holding at 500~600℃ for 2~6h and air cooling.

10. A pressure of 1100MPa + 120MPa as described in claim 1 1 / 2 Applications of high-strength, high-damage-tolerant titanium alloys in the aerospace field.

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