High-strength titanium alloy for additive manufacturing

Abstract

The invention provides a high-strength titanium alloy for additive manufacturing. The titanium alloy includes: 5.5 to 6.5 wt% of aluminum (Al); 3.0 to 4.5 wt% of vanadium (V); from 1.0 to 2.0 wt% molybdenum (Mo); from 0.3 to 1.5 wt% of iron (Fe); from 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% of zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% of carbon (C); a maximum of 0.25 wt% silicon (Si); the aluminum structure equivalent [Al] eq is in the range of 7.5 to 9.5 wt% and is defined by the following equation: [Al] eq = [Al] + [O] * 10 + [Zr] / 6, and wherein the molybdenum structure equivalent [Mo] eq is in the range of 6.0 to 8.5 wt% and is defined by the following equation: [Mo] eq = [Mo] + [V] / 1.5 + [Cr] * 1.25 + [Fe] * 2.5.

Description

TECHNICAL FIELD

[0001] The present application relates to titanium alloys, and more particularly to high strength alpha-beta titanium alloys for additive manufacturing. BACKGROUND

[0002] Titanium alloys generally exhibit a high strength-to-weight ratio, excellent corrosion resistance, and high temperature performance. As a result, titanium alloys are commonly used in the aerospace industry, for example, to manufacture various aircraft components, among others.

[0003] Titanium alloys are relatively expensive and can be difficult to machine into complex parts that meet aerospace specifications. This has led the aerospace industry to develop net- shape (or near-net shape) technologies, including additive manufacturing processes, which can reduce the amount of machining required.

[0004] Ti-6AI-4V is one of the most commonly used titanium alloys in the aerospace industry due to its ductility, as well as its relatively high tensile and shear strength. For many applications, the desired mechanical properties of Ti-6AI-4V are achieved under mill annealed conditions. Even greater strength can be obtained when Ti-6AI-4V is under solution treated and aged (STA) conditions. However, Ti-6AI-4V under solution treated and aged (STA) conditions is more expensive to manufacture and is limited to relatively small cross sections. Moreover, increasing the strength of Ti-6AI-4V under solution treated and aged (STA) conditions is typically at the expense of ductility.

[0005] Accordingly, those skilled in the art continue with research and development efforts in the field of titanium alloys and additive manufacturing. SUMMARY

[0006] A titanium alloy comprising (e.g., consisting essentially of): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); and the balance titanium, wherein the aluminum structural equivalent value [Al] eq is in the range of 7.5 to 9.5 wt% and is defined by the following equation:

[0007] [Al] eq = [Al] + [O] x 10 + [Zr] / 6, and

[0008] wherein the molybdenum structural equivalent value [Mo] eqWithin the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0009] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0010] A powder composition comprising (for example, substantially consisting of): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); and the balance being titanium, wherein the aluminum structural equivalent [Al] eq It is 7.5 to 9.5 wt%, and is defined by the following equation:

[0011] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0012] Among them, the molybdenum structural equivalent [Mo] eq It is 6.0 to 8.5 wt%, and is defined by the following equation:

[0013] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0014] A wire comprising (for example, substantially consisting of): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); and the balance being titanium, wherein the aluminum structural equivalent [Al] eq It is 7.5 to 9.5 wt%, and is defined by the following equation:

[0015] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0016] Among them, the molybdenum structural equivalent [Mo] eq It is 6.0 to 8.5 wt%, and is defined by the following equation:

[0017] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0018] A method for manufacturing additive manufacturing feedstock includes the step of pulverizing a titanium alloy composition comprising (for example, substantially consisting of): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); and the balance being titanium, wherein the aluminum structural equivalent [Al] eq It is 7.5 to 9.5 wt%, and is defined by the following equation:

[0019] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0020] Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0021] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0022] A method for manufacturing an additive manufacturing feedstock from a metallic raw material comprising (for example, substantially consisting of): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0023] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0024] Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0025] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5,

[0026] The method includes the following steps: (1) grinding a metal raw material to produce an intermediate powder; and (2) spheroidizing the intermediate powder to produce an additive manufacturing feed.

[0027] A method for manufacturing additive manufacturing feedstock includes the following steps: (1) melting an ingot comprising (e.g., substantially the following components): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0028] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0029] Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0030] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5,

[0031] (2) Transform the ingot into a forged billet at a β and / or α-β phase field temperature; (3) Machin the forged billet; (4) Hot roll at a β and / or α-β phase field temperature to produce rolled stock; (5) Anneal the rolled stock at a temperature of 550 °C to 788 °C (1022 °F to 1450 °F) for at least 0.5 hours; (6) Draw to produce wire with a nominal diameter of up to 3.175 mm (0.125 inches); and anneal at a temperature of 550 °C to 788 °C (1022 °F to 1450 °F) for at least 0.5 hours.

[0032] A manufacturing method includes additively manufacturing an component from an additive manufacturing feedstock comprising (for example, substantially consisting of): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0033] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0034] Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0035] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0036] Other aspects of the disclosed high-strength titanium alloy for additive manufacturing and related methods will become apparent from the following detailed description, drawings and appended claims. Attached Figure Description

[0037] Figure 1 It is a flowchart depicting the manufacturing process of a rod made of the disclosed titanium alloy;

[0038] Figure 2 This is a flowchart depicting one of the disclosed methods for manufacturing additive manufacturing feedstocks;

[0039] Figure 3 It is a flowchart depicting another disclosed method for manufacturing additive manufacturing feedstock;

[0040] Figure 4 It is a flowchart depicting yet another publicly disclosed method for manufacturing additive manufacturing feedstock;

[0041] Figure 5 The microstructure of a bar stock (diameter = 12.7 mm (0.5 inches)) made of the disclosed titanium alloy is depicted;

[0042] Figure 6 The microstructure of a bar stock (diameter = 101.6 mm (4 inches)) made of the disclosed titanium alloy is depicted;

[0043] Figure 7 The microstructure of a wire (diameter = 5.18 mm (0.204 inches)) made of the disclosed titanium alloy is depicted;

[0044] Figure 8 It is a flowchart of aircraft manufacturing and maintenance methods; and

[0045] Figure 9 This is a block diagram of an aircraft. Detailed Implementation

[0046] A high-strength forged titanium alloy for additive manufacturing is disclosed. The disclosed titanium alloy can be prepared as an additive manufacturing feedstock, such as in powder or thin wire form, has a chemical property that is effectively balanced with production capacity, and possesses high ultimate tensile strength and double shear strength, while maintaining a high level of plasticity under annealing conditions.

[0047] The disclosed titanium alloy comprises (for example, substantially the following components): 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); unavoidable impurities; and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0048] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0049] Among them, the molybdenum structural equivalent [Mo] eq It is 6.0 to 8.5 wt%, and is defined by the following equation:

[0050] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0051] The disclosed titanium alloy can be made into round rolled bars with diameters ranging from 8 mm to 31.75 mm (0.315 inches to 1.25 inches) and a minimum tensile strength of 165 ksi (1138 MPa) and a minimum double shear strength of 100 ksi (689 MPa) under annealed conditions.

[0052] The disclosed titanium alloy can be made into round rolled bars with diameters ranging from 32 mm to 101.6 mm (1.25 inches to 4 inches) and a minimum tensile strength of 160 ksi (1103 MPa) and a minimum double shear strength of 95 ksi (655 MPa) under annealed conditions.

[0053] Round rolled bars (8 mm to 101.6 mm (0.315 inches to 4.0 inches)) having the disclosed mechanical properties can be obtained using the following preparation method, which includes the steps of: (1) melting a titanium alloy ingot comprising: 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); unavoidable impurities; and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0054] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0055] Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0056] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5;

[0057] (2) Transform the ingot into a forged billet at a β and / or α-β phase field temperature; (3) Machin the forged billet; (4) Hot roll the billet at a β and / or α-β phase field temperature to produce a round billet; and (5) Anneal the round billet at a temperature of 550 °C to 788 °C (1022 °F to 1450 °F) for at least 0.5 hours.

[0058] See Figure 1 A specific method for manufacturing round rolled bars begins with a step of melting and casting an ingot in a vacuum electric arc furnace to achieve the following chemical composition: 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); unavoidable impurities; and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0059] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0060] Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0061] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0062] Additionally, converting the ingot into a forged billet (slab) at temperatures within the β and / or α-β phase fields helps eliminate the as-cast structure and prepares the metal structure for subsequent rolling, resulting in a billet with equiaxed coarse grains. To completely remove the gas-rich layer and surface defects generated by hot working, the forged billet is machined. Hot rolling of the machined billet is performed at heating temperatures within the β and / or α-β phase fields. The rolled billet is subsequently annealed at temperatures between 550 °C and 788 °C (1022 °F to 1450 °F) for at least 0.5 hours and cooled to room temperature to obtain a more balanced structure and reduce internal stress. Machining of the rolled billet is then performed to remove scale (surface layer, fouling) and the gas-rich layer.

[0063] The disclosed titanium alloy can be drawn into the form of round wire with a diameter of up to 10 mm (0.394 inches) and a minimum tensile strength of 168 ksi (1158 MPa) and a minimum double shear strength of 103 ksi (710 MPa) under annealed conditions.

[0064] The following manufacturing method can produce wires (up to 10 mm (0.394 inches)) having the disclosed mechanical properties, comprising the steps of: (1) melting a titanium alloy ingot comprising: 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); unavoidable impurities; and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0065] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0066] Among them, the molybdenum structural equivalent [Mo] eq It is 6.0 to 8.5 wt%, and is defined by the following equation:

[0067] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5;

[0068] (2) Transform the ingot into a forged billet at a β and / or α-β phase field temperature; (3) Machin the forged billet; (4) Hot roll at a β and / or α-β phase field heating temperature to produce a round billet; (5) Anneal the round billet at a temperature of 550 °C to 788 °C (1022 °F to 1450 °F) for at least 0.5 hours; (6) Draw to produce wire; and (7) Anneal the wire at a temperature of 550 °C to 788 °C (1022 °F to 1450 °F) for at least 0.5 hours.

[0069] See Figure 2A specific method for manufacturing wire begins with a step of melting and casting an ingot in a vacuum arc furnace to achieve the following chemical composition: 5.5 to 6.5 wt% aluminum (Al); 3.0 to 4.5 wt% vanadium (V); 1.0 to 2.0 wt% molybdenum (Mo); 0.3 to 1.5 wt% iron (Fe); 0.3 to 1.5 wt% chromium (Cr); 0.05 to 0.5 wt% zirconium (Zr); 0.2 to 0.3 wt% oxygen (O); up to 0.05 wt% nitrogen (N); up to 0.08 wt% carbon (C); up to 0.25 wt% silicon (Si); unavoidable impurities; and the balance being titanium, wherein the aluminum structural equivalent [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation:

[0070] [Al] eq = [Al] + [O]×10 + [Zr] / 6, and

[0071] Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation:

[0072] [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5.

[0073] Additionally, the method includes manufacturing a forged billet (slab), which is then machined in a rolling mill at a metal heating temperature in the β and / or α-β phase field. Rolling is performed to produce rolled material for subsequent winding. To relieve internal stress, the coil is annealed at a temperature of 550 °C to 788 °C (1022 °F to 1450 °F), followed by cooling to room temperature.

[0074] To remove the oxide scale and air-rich layer, the coil is chemically treated or machined. It is then drawn and rolled to produce wire with a diameter of up to 10 mm (0.394 inches).

[0075] To eliminate internal stress and improve structural balance, and to enhance plasticity, the resulting wire is annealed at temperatures ranging from 550 °C to 788 °C (1022 °F to 1450 °F), followed by air cooling. The annealed wire is then chemically treated or machined to the desired dimensions.

[0076] The disclosed filament can be used as an additive manufacturing feedstock. Therefore, by using the disclosed filament as an additive manufacturing feedstock, parts (such as components of aircraft) can be manufactured through additive manufacturing. For example, the disclosed filament can be supplied to a 3D printer, and instructions can be given to the 3D printer to print mesh (or near-mesh) parts using the disclosed filament.

[0077] Wires with a nominal diameter of up to 10 mm (0.394 inches) are disclosed, and these wires can be used in additive manufacturing. In one embodiment, the nominal diameter of the disclosed wire can be up to about 3.175 mm (0.125 inches). In another embodiment, the nominal diameter of the disclosed wire can be from about 0.127 mm (0.005 inches) to about 3.175 mm (0.125 inches). In yet another embodiment, the nominal diameter of the disclosed wire can be from about 0.127 mm (0.005 inches) to about 3 mm (0.118 inches). In yet another embodiment, the nominal diameter of the disclosed wire can be from about 1.27 mm (0.050 inches) to about 1.778 mm (0.070 inches). In yet another embodiment, the nominal diameter of the disclosed wire can be about 1.524 mm (0.060 inches).

[0078] The disclosed titanium alloy can be made into powder form. For example, the disclosed titanium alloy can be made into spheroidized powder form.

[0079] The disclosed powder can be used as an additive manufacturing feedstock. Therefore, by using the disclosed powder as an additive manufacturing feedstock, parts (such as components of aircraft, etc.) can be manufactured through additive manufacturing. For example, the disclosed powder can be supplied to a 3D printer, and instructions can be given to the 3D printer to print mesh (or near-mesh) parts using the disclosed powder.

[0080] By pulverizing a titanium alloy having the disclosed composition, an additive manufacturing feed in powder form can be produced. Although specific, non-limiting, exemplary suitable pulverization techniques are disclosed, those skilled in the art will understand that various pulverization techniques can be used without departing from the scope of this disclosure.

[0081] See Figure 3 An additive manufacturing feed 16 in powder form can be produced from the metal raw material 14 using a grinding and spheroidizing process 10. The metal raw material 14 can be any metallic material having the disclosed titanium alloy composition. For example, the metal raw material 14 can be an ingot, one or more round bars disclosed herein, unused / unwanted parts, chips, etc.

[0082] The disclosed grinding and spheroidizing process 10 for manufacturing additive manufacturing feed 16 in powder form may include the step of grinding 24 of metal raw material 14 to produce intermediate powder 26. Grinding 24 may transform metal raw material 14 into powder (intermediate powder 26) having desired physical properties (e.g., desired average particle size and distribution), which may depend on many factors, such as the intended use of additive manufacturing feed 16.

[0083] Various grinding techniques 24 may be used without departing from the scope of this disclosure. As a non-limiting example, grinding 24 may be performed in a planetary mill. As another non-limiting example, grinding 24 may be performed in a roller mill. As yet another non-limiting example, grinding 24 may be performed in a ball mill. Planetary mills, roller mills, and ball mills are capable of producing intermediate powders 26 with a particle size distribution particularly suitable for additive manufacturing.

[0084] The intermediate powder 26 can be ground 24 such that it has a particle size distribution that promotes close packing. In one embodiment, the intermediate powder 26 can be ground 24 such that it has an average particle size of about 5 μm to about 500 μm. In another embodiment, the intermediate powder 26 can be ground 24 such that it has an average particle size of about 10 µm to about 100 µm.

[0085] Optionally, the powder produced by grinding 24 can be sieved 28 to obtain the desired particle size distribution. For example, sieving 28 can produce intermediate powder 26 with a narrower particle size distribution, which can increase the density of the resulting additively manufactured parts / articles and improve their surface quality and mechanical properties. In one embodiment, sieving 28 can produce intermediate powder 26 with a particle size distribution in which at least 40% of the particles of intermediate powder 26 are within (+ / -) 20% of the average particle size. In another embodiment, sieving 28 can produce intermediate powder 26 with a particle size distribution in which at least 60% of the particles of intermediate powder 26 are within (+ / -) 20% of the average particle size. In yet another embodiment, sieving 28 can produce intermediate powder 26 with a particle size distribution in which at least 80% of the particles of intermediate powder 26 are within (+ / -) 20% of the average particle size.

[0086] Optionally, the metal feedstock 14 may be hydrogenated in the hydrogenation step 30 prior to grinding 24, thereby making the metal feedstock 14 more brittle and easier to grind 24. For example, the metal feedstock 14 may be hydrogenated in the hydrogenation step 30 by heating the metal feedstock 14 to a high temperature (e.g., 600-700 °C) for a period of time (e.g., 24 hours) in the presence of hydrogen (e.g., in a tube furnace).

[0087] When hydrogenation step 30 is performed, a corresponding dehydrogenation step 32 may also be performed subsequently. Dehydrogenation 32 may be performed after milling 24 and may be performed before or after optional sieving 28, thereby producing intermediate powder 26. For example, dehydrogenation 32 may be performed under vacuum at elevated temperatures (e.g., 550-700 °C) for a period of time (e.g., 72 hours).

[0088] See also Figure 3 The disclosed grinding and spheroidizing process 10 may further include spheroidizing 34 intermediate powder 26 to produce additive manufacturing feed 16 in powder form. Therefore, the particles of the additive manufacturing feed 16 in powder form can be substantially spherical. As used herein, "spherical" does not require a perfect sphere, but rather refers to a "basic sphere".

[0089] Various techniques can be used to spheroidize the intermediate powder 26 without departing from the scope of this disclosure. In one particular embodiment, spheroidizing 34 may include introducing particles of the intermediate powder 26 into a plasma (e.g., an inductively coupled plasma) to rapidly heat and melt the particles, followed by cooling. For example, the TEKSPHERO 200™, commercially available from Tekna Plasma Systems Inc. of Quebec, Canada, can be used to spheroidize the intermediate powder 26 34 using an inductively coupled plasma.

[0090] See Figure 4 The additive manufacturing feed 50 can be produced by atomizing 54 of a wire 52 having the disclosed peptide alloy composition to produce a powder form of additive manufacturing feed 50. In one particular embodiment, the atomization 54 of the wire 52 may include plasma atomization, wherein the wire 52 is fed through plasma to produce the powder form of additive manufacturing feed 50. Various other atomization techniques are contemplated and can be used without departing from the scope of this disclosure.

[0091] While various powdering techniques have been disclosed to obtain powders with the disclosed titanium alloy composition, alloying at the powder level is also envisioned. In other words, powders (or solidified masses formed from such powders) can be manufactured by mixing various powder compositions to produce powders with the disclosed titanium alloy composition.

[0092] The disclosed titanium alloy can be used in additive manufacturing, such as in powder form, wire form, or other suitable forms, while maintaining a high level of plasticity and high level of strength and bi-shear strength.

[0093] The disclosed titanium alloys exhibit a combination of high machinability and structural properties, achieved through the optimal selection of alloying elements and their proportions in the titanium alloys, as well as through the optimization of thermomechanical processing parameters.

[0094] The disclosed titanium alloy is made of α-β titanium alloy containing α stabilizer, neutral reinforcing agent and β stabilizer.

[0095] A group of α-stabilizers are formed from elements such as aluminum and oxygen. Introducing α-stabilizers into titanium alloys broadens the range of titanium solid solutions, reduces density, and improves the alloy's elastic modulus. Aluminum is the most effective reinforcing agent, increasing the strength-to-weight ratio of the alloy while improving both the strength and high-temperature behavior of titanium. When the aluminum concentration in the alloy is less than 5.5 wt%, the desired strength cannot be achieved, while concentrations exceeding 6.5% lead to an undesirable decrease in plasticity and a significant increase in the β-transformation temperature (BTT). Oxygen increases the temperature of the allotropic transformation of titanium. Oxygen present in the range of 0.2 wt% to 0.3 wt% increases strength without degrading plasticity. Nitrogen concentrations not exceeding 0.05 wt% and carbon concentrations not exceeding 0.08 wt% in the alloy have no significant effect on the reduction of plasticity at room temperature.

[0096] The neutral reinforcing agents disclosed in the titanium alloys include zirconium. Zirconium forms a wide variety of solid solutions with α-titanium, exhibiting similar melting points and densities, and improves corrosion resistance. A zirconium concentration selected in the range of 0.05 wt% to 0.5 wt% enhances the tendency for strength increase by improving the strength of the α-phase during cooling of heavier cross-section billets and effectively influencing the maintenance of metastable states.

[0097] The group of β stabilizers disclosed in this paper consists of isomorphous β stabilizers and eutectoid β stabilizers.

[0098] The disclosed titanium alloy's chemical composition consists of isomorphous β-stabilizers (e.g., vanadium and molybdenum). A vanadium concentration ranging from 3.0 wt% to 4.5 wt% ensures the stability of the β-phase, i.e., it inhibits the formation of the α2 superstructure in the α-phase and contributes to improved strength and ductility. A molybdenum concentration ranging from 1.0 wt% to 2.0 wt% ensures its complete dissolution in the α-phase, resulting in high levels of strength without deterioration of ductility. When the molybdenum concentration exceeds 2.0 wt%, the alloy's specific gravity increases, while the strength-to-weight ratio and ductility decrease.

[0099] The disclosed titanium alloy chemical composition is also provided by eutectoid β stabilizers (Cr, Fe, Si).

[0100] Adding iron in the range of 0.3 wt% to 1.5 wt% increases the volume fraction of the β phase, reducing strain resistance during hot working of the alloy, which helps prevent defects originating from hot working. Iron concentrations exceeding 1.5 wt% lead to segregation processes that form β spots during alloy melting and solidification, resulting in non-uniformity of structural and mechanical properties as well as deterioration of corrosion resistance.

[0101] Chromium concentrations were determined to be between 0.3 wt% and 1.5 wt% due to its ability to effectively enhance titanium alloys and act as a strong β-stabilizer. However, when alloying with chromium exceeds the determined maximum limit, there is a high probability of the formation of embrittled intermetallic compounds due to prolonged isothermal exposure and chemical inhomogeneity during ingot melting.

[0102] The acceptable maximum silicon concentration is 0.25 wt%. Within this limit, silicon is completely dissolved in the α phase, thus reinforcing the α solid solution and forming a small amount of β phase in the alloy. Additionally, adding silicon to the alloy increases its high-temperature stability. Silicon concentrations exceeding this limit lead to silicide formation, which results in reduced creep strength and material cracking.

[0103] The disclosed titanium alloy is based on the possibility of separating the strengthening effect of titanium alloys through alloying with α stabilizers, neutral reinforcing agents, and added β stabilizers. This possibility is demonstrated by the following considerations: Elements equivalent to aluminum primarily strengthen titanium alloys through solid solution strengthening, while β stabilizers primarily strengthen titanium alloys by increasing the amount of the stronger β phase. Therefore, for stable strength properties, there exists a marginal concentration of alloying elements. For this purpose, there exists a mechanism defined for controlling their proportions within the claimed composition range.

[0104] Structural aluminum ([Al)) alloys constrained by economics, strength, and processing standards were calculated for use in preparing fastener blanks. eq ) and molybdenum ([Mo] eq )equivalent.

[0105] Structural aluminum equivalent [Al] eq Set within the range of 7.5 to 9.5. This limitation can be explained by the following fact: [Al] eq Values ​​below 7.5 cannot guarantee the required consistency of mechanical properties, while [Al] eq Values ​​exceeding 9.5 lead to increased solid solution strengthening, which deteriorates plastic behavior and creates prerequisites for cracking during hot working.

[0106] The structural molybdenum equivalent value [Mo] eq The range of 6.0 to 8.5 is selected to ensure the stability of the required amount of β phase and the phase transformation after thermal exposure, in order to obtain alloys with high levels of strength properties.

[0107] The [Al] disclosed in this article eq and [Mo] eqThis is a baseline category for establishing, controlling, and effectively managing the manufacturing process to ensure high-quality components that precisely meet consumer requirements for structural and processing characteristics. The principles disclosed herein can compensate for the deficiencies of more expensive chemical elements by using equivalent amounts of cheaper alloying elements (including those included in certain amounts in incorporated scrap) within a specified strength equivalent and alloy chemical composition. Simultaneously, alloy costs can be reduced by 30% while consistently maintaining the high structural and operational performance of the components.

[0108] Example

[0109] Example 1

[0110] To test industrial applicability, ingots with the chemical composition shown in Table 1 were melted. The β-transformation temperature was 998 °C (1828 °F).

[0111]

[0112] The ingot was converted into a forged billet at the temperatures of the β and α-β phase fields. The billet was rolled at a final rolling temperature of 915 °C (1679 °F) to produce bars with a diameter of 12.7 mm (0.5 inches). The rolled bars were annealed at 600 °C (1112 °F) for 60 minutes and then air-cooled to room temperature. Mechanical tests and structural inspections were then performed. Table 2 shows the mechanical test results of the heat-treated bars. Figure 5 The microstructure of the heat-treated bar stock is shown at a magnification of 200x.

[0113]

[0114] Example 2

[0115] To produce bars with a diameter of 101.6 mm (4 inches), ingots with the chemical composition shown in Table 3 were melted. The alloy β-transformation temperature (BTT) determined by metallography was 988 °C (1810 °F).

[0116]

[0117] The ingot was converted into a forged billet at the temperatures of the β and α-β phase fields. The billet was rolled at 918 °C (1685 °F) to produce bars with a diameter of 101.6 mm (4 inches). Test specimens of the rolled bars, with a diameter of 101.6 mm (4 inches) and a length of 101.6 mm (4 inches), were annealed for 60 minutes at 600 °C (1112 °F). Subsequently, mechanical tests and structural inspections were performed in the longitudinal direction. Table 4 shows the results of the mechanical tests on the heat-treated bars, and... Figure 6The microstructure of the bar stock is shown at 200x magnification.

[0118]

[0119] Example 3

[0120] To produce wire with a diameter of 5.18 mm (0.204 inches), an ingot with the chemical composition shown in Table 5 was melted. The alloy β-transformation temperature (BTT) determined by metallography was 988 °C (1810 °F).

[0121]

[0122] The ingot was converted into a forged billet at temperatures in the β and α-β phase fields. The billet was rolled at 918 °C (1685 °F) to produce a billet with a diameter of 101.6 mm (4 inches). The 101.6 mm (4 inch) diameter billet was rolled into a 7.92 mm (0.312 inch) diameter billet and finally hot-worked in the α-β phase field. The 7.92 mm (0.312 inch) diameter billet was degassed in a vacuum furnace and then drawn in multiple stages to produce a wire with a diameter of 6.07 mm (0.239 inches). The wire was annealed under the following conditions: heated to 705 °C (1300 °F), soaked for 1 hour, and air-cooled. The wire was ground and polished, followed by sandblasting and pickling. The wire was then lubricated and sized to 5.18 mm (0.204 inches). Table 6 presents the mechanical test results of wire with a diameter of 5.18 mm (0.204 inches) after annealing. Figure 7 The microstructure of the wire is shown at a magnification of 800x.

[0123]

[0124] Examples 4-21 and Comparative Examples C1-C9

[0125] The use of the disclosed titanium alloy in additive manufacturing was evaluated. Test components with a T-shaped structure were additively manufactured using the disclosed additive manufacturing feedstock. Ten test components (Examples 4-13) had the chemical compositions shown in Table 7, while eight test components (Examples 14-21) had the chemical compositions shown in Table 8. All eighteen test components (Examples 4-21) were annealed at 1375 °F (746 °C) for two hours.

[0126]

[0127] For comparison, identical T-shaped test pieces (comparative examples C1-C9) were manufactured using standard Ti-6Al-4V additive manufacturing. The Ti-6Al-4V test pieces were heat-treated to subject them to solution treatment and aging (STA) conditions.

[0128] Tensile specimens were extracted from the test component and mechanically tested according to ASTM E8. The results are listed in Table 9.

[0129]

[0130] The annealed titanium alloys performed well compared to standard solution-treated and aged (STA) Ti-6Al-4V. It should be noted that Examples 11-14, 17-20, C6, and C7 exhibited fractured outer-quarter structures.

[0131] It can be like Figure 8 The aircraft manufacturing and maintenance method 100 shown, and as such Figure 9 Embodiments of this disclosure are described within the context of the illustrated aircraft 102. During pre-production, the aircraft manufacturing and maintenance method 100 may include the specification and design 104 of the aircraft 102 and the procurement of materials 106. During production, component / sub-component manufacturing 108 and system integration 110 of the aircraft 102 are performed. Subsequently, the aircraft 102 may undergo certification and delivery 112 for entry into service 114. When used by a consumer, the aircraft 102 is scheduled for routine maintenance and upkeep 116, which may also include modifications, reconfigurations, refurbishments, etc.

[0132] Each process of Method 100 may be performed or conducted by a systems integrator, a third party, and / or an operator (e.g., a consumer). For the sake of illustration, a systems integrator may include, but is not limited to, any number of aircraft manufacturers and main system subcontractors; a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, etc.

[0133] like Figure 9 As shown, an aircraft 102 produced by example method 100 may include a fuselage 118 having multiple systems 120 and an interior 122. Examples of the multiple systems 120 may include one or more of a propulsion system 124, an electrical system 126, a hydraulic system 128, and an environmental system 130. Any number of other systems may be included.

[0134] The disclosed high-strength titanium alloy can be used in any one or more stages of the aircraft manufacturing and maintenance method 100. As an example, the disclosed high-strength titanium alloy can be used to assemble or manufacture components or sub-components corresponding to component / sub-component manufacturing 108, system integration 110, and / or maintenance and servicing 116. As another example, the disclosed high-strength titanium alloy can be used to construct the fuselage 118. Additionally, during component / sub-component manufacturing 108 and / or system integration 110, one or more equipment examples, method examples, or combinations thereof can be utilized, for example, to substantially accelerate the assembly of the aircraft 102 (such as fuselage 118 and / or interior 122) or to reduce its cost. Similarly, when the aircraft 102 is in use, one or more system examples, method examples, or combinations thereof can be employed, such as, but not limited to, maintenance and servicing 116.

[0135] The disclosed high-strength titanium alloy is described in the context of aircraft; however, those skilled in the art will readily recognize that the disclosed high-strength titanium alloy can be used in a variety of applications. For example, the disclosed high-strength titanium alloy can be implemented in various types of transportation vehicles, including, for example, helicopters, passenger ships, automobiles, marine products (boats, motorboats, etc.). Various non-transportation applications are also envisioned, such as medical applications.

[0136] Although various aspects of the disclosed high-strength titanium alloys for additive manufacturing have been shown and described, various modifications will arise for those skilled in the art upon reading the specification. This application includes such modifications and is limited only by the scope of the claims.

Claims

1. A method for manufacturing a component, comprising: Additive manufacturing components made from feedstocks including titanium alloys. The titanium alloy comprises: 5.5 to 6.5 wt% aluminum; Vanadium content of 3.0 to 4.5 wt%; 1.0 to 2.0 wt% molybdenum; 0.3 to 1.5 wt% iron; 0.3 to 1.5 wt% chromium; Zirconium, 0.05 to 0.5 wt%; 0.2 to 0.3 wt% oxygen; Maximum 0.05 wt% nitrogen; Maximum 0.08 wt% carbon; Maximum 0.25 wt% silicon; and The balance of titanium, Among them, the aluminum structural equivalent value [Al] eq Within the range of 7.5 to 9.5 wt%, and defined by the following equation: [Al] eq = [Al] + [O]×10 + [Zr] / 6, and Among them, the molybdenum structural equivalent [Mo] eq Within the range of 6.0 to 8.5 wt%, and defined by the following equation: [Mo] eq = [Mo] + [V] / 1.5 + [Cr]×1.25 + [Fe]×2.5。 2. The method according to claim 1, wherein, Manufacturing the additive manufacturing feed includes: The titanium alloy is powdered.

3. The method according to claim 2, wherein, The powdering includes: Grinding includes the metallic raw material of the titanium alloy to produce an intermediate powder; and The intermediate powder is spheroidized to produce an additive manufacturing feedstock.

4. The method according to claim 2, wherein, The powdering includes atomizing the wire comprising the titanium alloy.

5. The method according to claim 1, wherein, Manufacturing the additive manufacturing feed includes: Melting an ingot containing the titanium alloy; The ingot is converted into a forged billet at a β and / or α-β phase field temperature; Machining the forged ingot; The forged ingot is hot-rolled at a heating temperature in the β and / or α-β phase field to produce rolled material; The rolled material is annealed at a temperature of 550 °C to 788 °C for at least 0.5 hours; The drawn and annealed rolled material is used to produce wire with a nominal diameter of up to 3.175 mm; and The wire is annealed at a temperature of 550 °C to 788 °C for at least 0.5 hours.

6. The method according to claim 1, wherein, The titanium alloy is essentially composed of titanium, aluminum, vanadium, molybdenum, iron, chromium, zirconium, and oxygen, as well as optional nitrogen, carbon, and silicon, and unavoidable impurities.

7. The method according to claim 1, wherein, The titanium alloy is in powder form, spheroidized powder form, or formed into wire.

8. The method according to claim 7, wherein, The wire has a nominal diameter of up to 3.175 mm.

9. The method according to claim 7, wherein, The wire has a nominal diameter of 0.127 mm to 3 mm.

10. The method according to claim 7, wherein, The wire has a nominal diameter of 1.27 mm to 1.778 mm.

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