Titanium alloy wire for electric arc additive manufacturing and method for manufacturing the same

Abstract

A titanium alloy wire for electric arc additive manufacturing, characterized by comprising the following components in percentage by mass: Al: 7.15%-7.47%, Mo: 1.85%-1.90%, V: 2.25%-2.35%, Zr: 2.50%-4.2%, and the balance being Ti and inevitable impurities: Fe<=0.1%, C<=0.015%, H<=0.003%, O<=0.12%, N<=0.012%. Compared with the prior art, the titanium alloy wire for electric arc additive manufacturing prepared by the application can be continuously formed and has good high-temperature strength and plasticity.

Description

Technical Field

[0001] This invention relates to the field of materials for arc additive manufacturing, and more particularly to a titanium alloy wire for arc additive manufacturing and its preparation method. Background Technology

[0002] Titanium alloys, with their high specific strength, corrosion resistance, and high temperature resistance, are widely used in marine development, shipbuilding, aerospace, and other fields. In recent years, with the development of additive manufacturing technology, high-performance titanium alloys have become a hot topic in various industries. However, in the manufacturing of large and complex titanium alloy components, their low thermal conductivity, high chemical reactivity, and processing difficulty present challenges. Traditional casting, forging, and welding processes result in long manufacturing cycles, high costs, low material utilization, and poor product adaptability, significantly limiting the application and promotion of titanium alloys in key areas.

[0003] Titanium alloy arc additive manufacturing technology uses an electric arc as the heat source and titanium alloy wire as the filler metal. It is less prone to defects such as incomplete fusion, and boasts high forming efficiency, high material utilization, and strong structural design flexibility. It is suitable for the rapid, integral manufacturing of large and complex titanium alloy components, and has broad application prospects in aerospace, automotive, and shipbuilding large and complex structural parts. However, current arc additive manufacturing of titanium alloy components typically uses commercially available welding wire, which often has poor build-up and low forming accuracy. Furthermore, under the action of continuous multi-layered arcs, there is severe element loss and segregation, resulting in low element content in the additive components and reduced service performance.

[0004] Therefore, there is a need for a titanium alloy wire for arc additive manufacturing that can meet the requirements of continuous forming in arc additive manufacturing and has good high-temperature strength and plasticity in the stacked state, as well as its preparation method. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a titanium alloy wire for arc additive manufacturing that can be continuously formed.

[0006] The second technical problem to be solved by the present invention is to provide a method for preparing titanium alloy wire for arc additive manufacturing.

[0007] The technical solution adopted by the present invention to solve the first technical problem mentioned above is as follows: a titanium alloy wire for arc additive manufacturing, characterized in that, by mass percentage, it comprises the following components: Al: 7.15%-7.47%, Mo: 1.85%-1.90%, V: 2.25%-2.35%, Zr: 2.50%-4.2%, with the balance being Ti and unavoidable impurities: Fe≤0.1%, C≤0.015%, H≤0.003%, O≤0.12%, N≤0.012%.

[0008] The following analysis examines the role of alloying elements in this invention and the reasons why they fall within the controlled composition range:

[0009] Al: Aluminum is the most commonly used α-stabilizing element in titanium alloys. Through substitution solid solution strengthening, it can improve the room temperature and high temperature strength, as well as the thermal strength of titanium alloys. Approximately all types of titanium alloys, both domestically and internationally, contain an appropriate amount of aluminum. Generally, it is believed that excessive aluminum content, exceeding 7 wt.%, easily leads to the formation of a brittle Ti3Al phase. Insufficient Al content reduces the room temperature and high temperature strength of arc additive manufacturing titanium alloys. During arc additive manufacturing, the aluminum burn-off rate is approximately 5%. To avoid the formation of a brittle phase and ensure the stacked state meets performance requirements, the Al content in this invention is controlled at 7.15%-7.47%.

[0010] Mo (Mo): Molybdenum has the same crystal structure and similar atomic radius as titanium, lowers the β-transformation temperature, and is infinitely soluble in the β-phase, thus expanding the β-phase region and increasing its stability. Compared to other β-phase stabilizing elements, molybdenum has a more significant strengthening effect, improving both room temperature and high temperature strength, and increasing hardenability. However, excessive molybdenum content increases cost and reduces ductility and toughness. Therefore, in the titanium alloy wire of this invention, the Mo content is controlled at 1.85%-1.90%.

[0011] V: Vanadium plays a similar role to Mo. Adding a small amount of vanadium can give the alloy good thermal stability and high-temperature creep resistance. Therefore, the vanadium content in this invention is 2.25-2.35%.

[0012] Zr: Zr is a neutral element in titanium alloys and has little effect on the β-transformation temperature. Zirconium has similar properties to titanium and its atomic size is also very close, allowing it to be infinitely dissolved in both the α and β phases. Zirconium has weak room-temperature strengthening but strong high-temperature strengthening, and when added with other elements, it plays a supplementary strengthening role. Therefore, the Zr content in the titanium alloy wire of this invention is controlled at 2.5%-4.2%.

[0013] Preferably, the titanium alloy in the stacked state manufactured by the titanium alloy wire for arc additive manufacturing has a high-temperature tensile strength ≥740MPa, a yield strength ≥551MPa, and an elongation ≥9.3%.

[0014] The technical solution adopted by the present invention to solve the second technical problem mentioned above includes the following steps:

[0015] S1. Vacuum melting: Using Al-60Mo, Al-55V, aluminum briquettes, TiO2, Ti-32Fe, sponge titanium, and sponge zirconium as raw materials, the mixture is first vacuum melted according to the mass percentages of Al: 7.15-7.47%, Mo: 1.85-1.90%, V: 2.25-2.35%, and Zr: 2.5-4.2% to obtain a preliminary melt ingot.

[0016] S2. Preparation of electrode samples: The initial melted ingot is forged to obtain electrode samples;

[0017] S3. Secondary melting: The electrode sample is remelted by electroslag remelting to obtain a secondary ingot.

[0018] S4. High-temperature forging: The secondary ingot is forged at high temperature to obtain bar stock;

[0019] S5. High-temperature rolling: The bar is hot rolled at high temperature to obtain a 9.5mm diameter coil, and then the oxide scale is removed and peeled off to a 9.0mm diameter coil.

[0020] S6. The coil is drawn multiple times to obtain a wire with a diameter of 1.4 mm, and then the oxide scale is removed to obtain a wire with a diameter of 1.2 mm.

[0021] S7. Vacuum annealing: The wire is subjected to final vacuum annealing treatment.

[0022] Preferably, the vacuum degree in step S1 is less than 5 MPa, the temperature at the center of the arc region is higher than or equal to 2000°C, and the temperature of the entire arc region is 1800°C.

[0023] Preferably, the electroslag remelting parameters in step S3 are: current: 18-30KA, voltage: 28-38V, arc stabilization current: 5-20A, and vacuum degree less than 5Pa.

[0024] Preferably, the high-temperature forging step S4 is as follows: the ingot is held at 850°C for 1.5 hours, then held at 1150°C for 6 hours, forged into a square bar, with a final forging temperature of not less than 815°C, and then air-cooled after final forging.

[0025] Preferably, the specific process of high-temperature rolling in step S5 is as follows: heating temperature is 950℃, followed by holding at that temperature for 3 hours, and then hot continuous rolling.

[0026] Preferably, the specific process of step S6 is: ① First multiple continuous rolling, with the diameter changing from Φ9.0mm to Φ5.5mm;

[0027] ② After heat preservation at 700-740℃, air cooling is performed;

[0028] ③ Second multiple continuous drawing, diameter changes from Φ5.5→Φ4.2→Φ3.3mm;

[0029] ④ After heat preservation at 700-740℃, air cool;

[0030] ⑤ The third multiple continuous drawing process resulted in a diameter change of Φ3.3→Φ2.4→Φ1.4mm;

[0031] ⑥ Remove oxide scale to 1.2mm.

[0032] Preferably, the vacuum annealing process of S7 is as follows: heat treatment at 750°C for 6 hours, followed by cooling.

[0033] Compared with the prior art, the advantages of the present invention are as follows:

[0034] The titanium alloy wire prepared by this invention exhibits stable arc additive manufacturing process, good formability of the clad metal, and absence of defects such as porosity and cracks, making it suitable for arc additive manufacturing of titanium alloy components. The titanium alloy wire prepared by this invention also demonstrates excellent tensile properties in the clad metal deposition state during arc additive manufacturing, with a high-temperature tensile strength exceeding 740 MPa at 500℃, a yield strength exceeding 551 MPa, and an elongation maintained above 9.3%, enabling continuous forming. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the embodiments.

[0036] The alloy composition of the titanium alloy wire for arc additive manufacturing in the three embodiments of the present invention is shown in Table 1. Examples 1 to 3 were prepared using the method of the present invention.

[0037] Example 1

[0038] S1. Vacuum melting: The titanium alloy wire ingot is initially melted using a vacuum induction furnace at a vacuum level of 5 MPa.

[0039] S2. Preparation of electrode samples: The initial melted ingot is forged to obtain electrode samples.

[0040] S3. Secondary melting: Vacuum melting is carried out using the electroslag remelting method with a current of 20KA, a voltage of 30V, a stable arc current of 5A, a vacuum degree of less than 5Pa, a temperature of 2000℃ at the center of the arc zone, and a temperature of 1800℃ in the remaining arc zones.

[0041] S4. High-temperature forging: The ingot obtained from the secondary melting is placed in a furnace and heated to 850℃ and held for 1.5 hours, then heated to 1150℃ and held for 6 hours, forging into a 210×210mm square bar. The final forging temperature is 900℃, followed by air cooling. After one tempering, the die is opened, air cooled, and ground.

[0042] S5. High-temperature rolling: The square bar is held at 950℃ for 3 hours and then hot rolled multiple times to obtain a 9.5mm wire rod.

[0043] S6. Pickling the coils to remove oxide scale down to 9.0mm diameter, washing and drying them, then applying a coating treatment, drying at 100℃, and rolling: First, multiple continuous rolling with diameter changes from Φ9.0 to Φ5.5, followed by online annealing at 720℃ for 2 hours; second, multiple continuous drawing with diameter changes from Φ5.5 to Φ4.2 to Φ3.3, followed by online annealing at 720℃ for 2 hours; third, multiple continuous drawing with diameter changes from Φ3.3 to Φ2.4 to Φ1.4, followed by online annealing at 720℃ for 2 hours, removing oxide scale down to Φ1.2, washing, and drying to obtain the wire material.

[0044] S7. Vacuum annealing: The obtained wire is subjected to vacuum annealing treatment, held at 750℃ for 6 hours, and cooled in the furnace to obtain titanium alloy wire for arc additive manufacturing.

[0045] CMT arc additive manufacturing forming experiments were conducted using prepared titanium alloy wire. A 20mm thick titanium alloy substrate was used as the substrate. Local shielding was employed, and argon gas was used. The wire feed speed was 4 m / min, the current was 120 A, the voltage was 20 V, and the scanning speed was 0.016 m / s. Tensile specimens were taken along the welding torch movement direction. M10 standard tensile specimens were used, and tensile properties were tested at 500℃ for 15 min. The mechanical properties are shown in Table 2.

[0046] Example 2

[0047] S1. Vacuum melting: The titanium alloy wire ingot is initially melted using a vacuum induction furnace at a vacuum level of 3 MPa.

[0048] S2. Preparation of electrode samples: The initial melted ingot is forged to obtain electrode samples.

[0049] S3. Secondary melting: Vacuum melting is carried out using the electroslag remelting method with a current of 20KA, a voltage of 35V, an arc stabilization of 10A, a vacuum degree of 3Pa, a temperature of 2100℃ at the center of the arc zone, and a temperature of 1800℃ in the remaining arc zones.

[0050] S4. High-temperature forging: The ingot obtained from the secondary melting is placed in a furnace and heated to 850℃ and held for 1.5 hours, then heated to 1150℃ and held for 6 hours, forging into a 210×210mm square bar. The final forging temperature is 900℃, followed by air cooling. After one tempering, the die is opened, air cooled, and ground.

[0051] S5. High-temperature rolling: The square bar is held at 950℃ for 3 hours and then hot rolled multiple times into a 9.5mm wire rod.

[0052] S6. Pickle the wire rod to remove the oxide scale until it reaches a diameter of 9.0 mm. After washing and drying, perform a coating treatment. After drying at 100℃, roll the wire rod. The diameter changes from Φ9.0 to Φ5.5 in the first multiple continuous rolling process. After annealing at 720℃ for 2 hours, the diameter changes from Φ5.5 to Φ4.2 to Φ3.3 in the second multiple continuous drawing process. After annealing at 720℃ for 2 hours, the diameter changes from Φ3.3 to Φ2.4 to Φ1.4 in the third multiple continuous drawing process. After annealing at 720℃ for 2 hours, the oxide scale is removed to Φ1.2. The wire rod is then washed and dried to obtain the filament.

[0053] S7. Vacuum annealing: The obtained wire is subjected to vacuum annealing treatment, held at 750℃ for 6 hours, and cooled in the furnace to obtain titanium alloy wire for arc additive manufacturing.

[0054] CMT arc additive manufacturing forming experiments were conducted using the prepared titanium alloy wire. The substrate was a 20mm thick titanium alloy substrate, and a local gas protection method was adopted. The gas was argon, the wire feed speed was 4m / min, the current was 130A, the voltage was 22V, and the scanning speed was 0.017m / s. Tensile specimens were taken along the direction of welding torch movement. The specimens were M10 standard tensile specimens, and tensile properties were tested at 500℃ for 15min. The mechanical properties are shown in Table 2.

[0055] Example 3

[0056] S1. Vacuum melting: The titanium alloy wire ingot is initially melted using a vacuum induction furnace with a vacuum degree of 1 MPa.

[0057] S2. Preparation of electrode samples: The initial melted ingot is forged to obtain electrode samples.

[0058] S3. Secondary melting: Vacuum melting is carried out using the electroslag remelting method with a current of 30KA, a voltage of 38V, a stabilizing arc current of 15A, a vacuum degree of 1Pa, a temperature of 2200℃ at the center of the arc zone, and a temperature of 1800℃ in the remaining arc zones.

[0059] S4. High-temperature forging: The ingot obtained from the secondary melting is placed in a furnace and heated to 850℃ and held for 1.5 hours, then heated to 1150℃ and held for 6 hours, forging into a 210×210mm square bar. The final forging temperature is 900℃, followed by air cooling. After one tempering, the die is opened, air cooled, and ground.

[0060] S5. High-temperature rolling: The square bar is held at 950℃ for 3 hours and then hot rolled multiple times into a 9.5mm wire rod.

[0061] S6. Pickle the coils to remove oxide scale until they reach a diameter of 9.0 mm. After washing and drying, perform a coating treatment. After drying at 100℃, roll the coils. The diameter changes sequentially through multiple continuous rolling processes: Φ9.0 → Φ5.5. Then, anneal online at 720℃ for 2 hours. Next, draw the coils continuously through multiple continuous drawing processes: Φ5.5 → Φ4.2 → Φ3.3. Then, anneal online at 720℃ for 2 hours. Finally, draw the coils continuously through multiple continuous drawing processes: Φ3.3 → Φ2.4 → Φ1.4. Then, anneal online at 720℃ for 2 hours. Remove the oxide scale until the diameter reaches Φ1.2. Wash the coils and dry them to obtain the wire material.

[0062] S7. Vacuum annealing: The obtained wire is subjected to vacuum annealing treatment, held at 750℃ for 6 hours, and cooled in the furnace to obtain titanium alloy wire for arc additive manufacturing.

[0063] CMT arc additive manufacturing forming experiments were conducted using prepared titanium alloy wire. A 20mm thick titanium alloy substrate was used as the substrate. Local shielding was employed, with argon gas as the gas source. The wire feed speed was 4 m / min, the current was 135 A, the voltage was 22 V, and the scanning speed was 0.02 m / s. Tensile specimens were taken along the welding torch movement direction. M10 standard tensile specimens were used, and tensile properties were tested at 500℃ for 15 min. The mechanical properties of the titanium alloy in its deposited state are shown in Table 2.

[0064] Table 1 Alloy composition of titanium alloy wire

[0065] Case Al Mo V Zr C Fe O N H Ti Example 1 7.15 1.89 2.25 2.52 0.014 0.07 0.08 0.012 0.002 margin Example 2 7.30 1.85 2.30 3.05 0.01 0.08 0.09 0.011 0.003 margin Example 3 7.47 1.88 2.35 4.12 0.006 0.1 0.06 0.011 0.002 margin Comparative Example 6.97 1.9 2.1 1.62 0.009 0.09 0.1 0.01 0.004 margin

[0066] Table 2. High-temperature mechanical properties test results of titanium alloy wire arc additive cladding metal in the examples.

[0067] Case Tensile strength (MPa) Yield strength (MPa) Elongation (%) Example 1 740 551 13.5 Example 2 802 592 10.5 Example 3 825 613 9.3 Comparative Example 617 495 20.0

[0068] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A method for preparing titanium alloy wire for arc additive manufacturing, characterized in that: Includes the following steps: S1. Vacuum melting: Using Al-60Mo, Al-55V, aluminum briquettes, TiO2, Ti-32Fe, sponge titanium, and sponge zirconium as raw materials, the mixture is first vacuum melted according to the mass percentages of Al: 7.15-7.47%, Mo: 1.85-1.90%, V: 2.25-2.35%, and Zr: 2.5-4.2% to obtain a preliminary melt ingot. S2. Preparation of electrode samples: The initial melted ingot is forged to obtain electrode samples; S3. Secondary melting: The electrode sample is remelted by electroslag remelting to obtain a secondary ingot. S4. High-temperature forging: Forging the secondary ingot to obtain bar stock; S5. High-temperature rolling: The bar is hot-rolled to obtain a wire rod with a diameter of 9.5 mm, and then the oxide scale is removed and peeled off to a wire rod with a diameter of 9.0 mm. S6. The coil is drawn multiple times to obtain a wire with a diameter of 1.4 mm, and then the oxide scale is removed to obtain a wire with a diameter of 1.2 mm. S7. Vacuum annealing: The de-oxidized wire is subjected to final vacuum annealing to obtain titanium alloy wire. The titanium alloy wire comprises the following components by mass percentage: Al: 7.15%-7.47%, Mo: 1.85%-1.90%, V: 2.25%-2.35%, Zr: 2.50%-4.2%, balance Ti and unavoidable impurities: Fe≤0.1%, C≤0.015%, H≤0.003%, O≤0.12%, N≤0.012%.

2. The method for preparing titanium alloy wire for arc additive manufacturing according to claim 1, characterized in that: The titanium alloy wire used in the arc additive manufacturing process has a high-temperature tensile strength of ≥740MPa, a yield strength of ≥551MPa, and an elongation of ≥9.3% at 500℃ in the stacked state.

3. The method for preparing titanium alloy wire for arc additive manufacturing according to claim 1, characterized in that: The vacuum degree in step S1 is less than 5 MPa, the temperature at the center of the arc region is ≥2000℃, and the temperature of the arc region other than the center of the arc region is 1800℃.

4. The method for preparing titanium alloy wire for arc additive manufacturing according to claim 1, characterized in that: The electroslag remelting parameters in step S3 are: current: 18-30KA, voltage: 28-38V, arc stabilization current: 5-20A, and vacuum degree: less than 5Pa.

5. The method for preparing titanium alloy wire for arc additive manufacturing according to claim 1, characterized in that: The high-temperature forging process in step S4 is as follows: the ingot is held at 850℃ for 1.5 hours, then held at 1150℃ for 6 hours, forged into a square bar with the die closed, and the final forging temperature is not lower than 815℃. After the final forging, the die is opened, and the ingot is air-cooled after tempering.

6. The method for preparing titanium alloy wire for arc additive manufacturing according to claim 1, characterized in that: The specific process of high-temperature rolling in step S5 is as follows: heating temperature is 950℃, followed by holding at that temperature for 3 hours, and then hot continuous rolling.

7. The method for preparing titanium alloy wire for arc additive manufacturing according to claim 1, characterized in that: The specific process of step S6 is: ① First multi-stage continuous rolling; ② After heat preservation at 700-740℃, air cooling is performed; ③ Second multiple continuous drawing; ④ After heat preservation at 700-740℃, air cool; ⑤ Third multiple continuous drawing; ⑥ Remove oxide scale.

8. The method for preparing titanium alloy wire for arc additive manufacturing according to claim 1, characterized in that: The vacuum annealing process of S7 is as follows: after holding at 750℃ for 6 hours, it is cooled.