A high-strength 2319 aluminum alloy welding wire and its preparation method

Abstract

This invention relates to the field of welding materials technology, and more particularly to a high-strength 2319 aluminum alloy welding wire and its preparation method. Currently, the mechanical properties of 2319 aluminum alloy welding wire are insufficient to meet the requirements of specialized fields such as military applications, and its preparation is costly and difficult. To address these problems, this invention provides a high-strength 2319 aluminum alloy welding wire and its preparation method. Through novel composition design and process optimization, on the one hand, the grain size can be refined, and the microstructure improved to achieve greater uniformity; on the other hand, continuous casting and rolling of the 2319 aluminum alloy welding wire is achieved, successfully producing 2319 aluminum alloy wire rods with low hydrogen content and uniform microstructure, ultimately yielding a finished welding wire with excellent X, Y, and Z triaxial tensile properties of the deposited metal.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, specifically relating to a high-strength 2319 aluminum alloy welding wire and its preparation method. Background Technology

[0002] In recent years, with the rapid development of additive manufacturing technology, 2319 aluminum alloy has occupied an important position in the high-end welding and additive manufacturing needs of aerospace, military equipment, rail transportation and other fields due to its excellent heat-treatable properties and high strength characteristics.

[0003] Currently, the casting extrusion method is commonly used in the industry to produce 2319 welding wire. The specific process is as follows: the alloy melt is cast into a casting rod with a large cross-sectional size. The problem of coarse columnar crystals and compositional segregation caused by the difference in cooling rate in the core of the casting rod is improved by solution treatment. Then, the wire rod is obtained by hot extrusion. This process has the following defects: (1) Uneven structure: the difference in cooling inside and outside of the large cross-section casting rod leads to grain coarsening and compositional segregation. Solution treatment is difficult to completely improve the problem, which affects the stability of welding wire performance; (2) The wire rod length is limited (≤40 meters). The drawing requires repeated jointing. It is difficult to maintain isotropy at the joint, which leads to unstable product quality and restricts continuous production; (3) When aluminum-copper alloy solidifies, Cu diffuses quickly and has a wide crystallization range, which leads to poor fluidity, shrinkage porosity and high tendency to hot cracking, which increases the cost. The casting extrusion method is difficult to meet the requirements of welding wire performance consistency, forming stability and cost control in the manufacturing of complex components.

[0004] Although continuous casting and rolling technology has been widely applied in the production of 4-series (Al-Si) and 5-series (Al-Mg) aluminum alloy welding wires, its promotion in the 2-series (Al-Cu) alloy field faces severe challenges. Therefore, there is an urgent need to develop a continuous casting and rolling preparation method adapted to the characteristics of 2319 aluminum alloy to overcome the technical bottlenecks of high material loss, poor microstructure uniformity, and insufficient continuity in traditional processes, and to meet the core requirements of high-end fields for high-strength welding wires that are low-cost, high-performance, and have a long service life. Summary of the Invention

[0005] To address the aforementioned technical problems, this patent provides a high-strength 2319 aluminum alloy welding wire and its preparation method, enabling continuous casting and rolling of the 2319 aluminum alloy welding wire while maintaining high strength. The preparation method includes the following steps:

[0006] (1) Smelting of aluminum liquid; The mass percentage of the composition of the smelted aluminum liquid is as follows: Cu 5.6-6.4, Fe 0.05-0.10, Mn 0.1-0.4, Si 0.02-0.12, Zr 0.15-0.30, Mg 0.005-0.015, Ti 0.1-0.2, V 0.03-0.15, Sc 0.3-0.5, Y 0.05-0.20, with the balance being Al;

[0007] (2) Continuous casting: When the molten aluminum enters the casting tank, positive pressure electromagnetic stirring is applied, with a stirring power of 70-150W / t. After the molten aluminum reaches the cooling steel strip, three water cooling channels are turned on, with the water flow rate controlled at 10~20L / min and decreasing sequentially; the cooling steel has a high thermal conductivity, which makes the molten aluminum cool evenly;

[0008] (3) Continuous rolling: Before the casting reaches the rolling device, high-frequency heating and resistance heating are turned on so that the surface and internal temperature can reach 370-410℃. Within this range, aluminum-copper alloy has good thermoplasticity and can be rolled more easily.

[0009] (4) Wire rod treatment: Ф6.0-8.0mm wire rod produced by continuous casting and rolling is subjected to homogenization annealing at 500-530℃ for 8 hours, followed by four rough drawing processes to obtain wire rod with a diameter of 2.5-3.5mm, which is then subjected to recrystallization annealing at 500-530℃ for 10 hours. It can then be cold-worked.

[0010] In an embodiment of the present invention, the mass percentage of the components of the smelted aluminum liquid in step (1) is: Cu 6.1-6.3, Fe 0.05-0.06, Mn 0.23-0.27, Si 0.05, Zr 0.19-0.21, Mg 0.007-0.012, Ti 0.14-0.15, V 0.08-0.10, Sc 0.40-0.45, Y 0.12-0.13, with the balance being Al.

[0011] This invention produces 2319 aluminum alloy welding wire using continuous casting and rolling technology, which greatly reduces production costs and solves the problems of casting shrinkage defects and rolling difficulties. This invention also improves the mechanical properties of the weld metal by adding rare earth elements to the alloy.

[0012] This invention improves the tensile strength of the weld metal by adding rare earth elements Sc and Y to the alloy; ensures the feeding of the casting by applying electromagnetic stirring and using cooling steel strips with good thermal conductivity during continuous casting; and makes the casting temperature more uniform by using high-frequency heating and resistance heating in combination during continuous rolling, thus ensuring its good thermoplasticity, greatly reducing the difficulty of rolling, avoiding the occurrence of crystallization cracks, and solving the technical problem of "high difficulty in continuous casting and rolling of 2319 aluminum alloy welding wire and low mechanical properties of weld metal".

[0013] The beneficial effects of this invention are:

[0014] (1) The traditional casting and extrusion technology of 2319 aluminum alloy welding wire requires solution treatment of the casting before it can be extruded into wire rod, which not only increases the time cost and reduces the material utilization rate, but also requires multiple joints in the subsequent cold working process, resulting in unstable product quality. The present invention realizes the continuous casting and rolling technology of 2319 aluminum alloy welding wire, which greatly reduces the cost. The prepared welding wire has a uniform structure and a lower diffusible hydrogen content.

[0015] (2) By adding electromagnetic stirring and using cooling steel strip with better thermal conductivity during the continuous casting process, the present invention greatly reduces shrinkage defects and ensures the internal quality of aluminum rods; in the subsequent continuous rolling process, the combination of high frequency heating and resistance heating ensures that the casting is in a suitable plastic temperature range and eliminates the phenomenon of crystallization cracks in the rolling process.

[0016] (3) By adding a certain amount of Zr, Ti, V, Sc and Y elements to the alloy composition, the present invention refines the internal grain structure of the alloy and improves the mechanical properties of the deposited metal through the synergistic effect of aluminum liquid alloy composition design and process optimization. After heat treatment, the mechanical properties can reach more than 450 MPa, and the mechanical properties in the X, Y and Z directions are relatively uniform. Attached Figure Description

[0017] Figure 1 Distribution of inclusions in wire rod as shown in Example 1;

[0018] Figure 2 Distribution of inclusions in wire rod as shown in Example 2;

[0019] Figure 3 Example 2: Second phase distribution of wire rod;

[0020] Figure 4 The metallographic structure of the welded joint in Example 1 contains α(Al) solid solution + CuAl2 + a small amount of (CuAl2 + S(CuMgAl2) eutectic + intragranular precipitates, wherein the magnification of a is 200× and the magnification of b is 500×.

[0021] Figure 5 The images shown are of the bar material during the rolling process in Comparative Example 2, where a represents a crack and b represents a splitting defect.

[0022] Figure 6 The images shown are of the bar material during the rolling process in Comparative Example 5, where a and b are both cracks.

[0023] Figure 7 Metallographic photograph of wire rod (Comparative Example 6);

[0024] Figure 8 For arc additive manufacturing of printed models;

[0025] Figure 9The machining dimensions for the pull rod sample. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] The specific steps of the aluminum smelting method described in the following examples and comparative examples are as follows:

[0028] (1) Before smelting, the furnace should be cleaned with pure aluminum (99.99% aluminum ingot) to remove the influence of other impurities on the alloy composition;

[0029] (2) Put aluminum ingots and Al-Cu master alloy into a smelting furnace, heat the temperature to 850-900℃, and after they are completely melted, keep the temperature for 15 minutes and stir electromagnetically. Raise the temperature to 900-1000℃ and add Al-Sc and Al-Y master alloys. Stir thoroughly. Lower the temperature to 800-850℃ and then add Al-7Ti, Al-10Zr and Al-3V in sequence and stir electromagnetically.

[0030] (3) Add refining agent MnCl2, with a mass fraction of 0.3% in the furnace, and refine at 750-820℃, then let stand for 10-20 minutes;

[0031] (4) Introduce 99.999% pure argon to remove gas, and then remove the slag;

[0032] (5) After the sample is tested and found to be qualified, the gas is removed and filtered before casting.

[0033] Example 1

[0034] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0035] (1) After the aluminum liquid is smelted, it is poured into a casting tank and cast while a positive pressure electromagnetic stirring is applied (the stirring power reaches 80W / t). The mass percentage of the components of the smelted aluminum liquid is shown in the table below:

[0036]

[0037] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0038] (3) The aluminum rod after continuous casting is trapezoidal. High frequency heating and resistance heating are turned on. The machine display temperature is 400℃ and the actual temperature is 392℃. After 7 rolling processes, a wire rod with a diameter of 7.0mm is obtained.

[0039] (4) After the wire rod is homogenized and annealed at 500℃ for 8 hours, it is rough drawn 4 times to obtain a wire of 3.0 mm. Then it is recrystallized and annealed at 500℃ for 10 hours, and then it can be cold-processed into finished wire of Φ1.6 mm or Φ1.2 mm.

[0040] The tensile properties of the finished yarn were tested according to the standard GB / T 228.1-2021. The test samples were produced from the finished yarn through arc additive manufacturing (e.g., Figure 8 As shown), it undergoes heat treatment (530℃×50min, 175℃×20h), and is then processed into a drawing rod by wire cutting (dimensions as shown). Figure 9 The test was conducted using the equipment and printing process shown in the table below:

[0041]

[0042] The test results are shown in Table 1 below (where X, Y, and Z are the three directions, left-hand rule, X1-X3, Y1-Y3, and Z1-Z3 are the three test results in the X, Y, and Z directions).

[0043] As can be seen from the table, the tensile strength of the deposited metal of the 2319 aluminum alloy welding wire prepared by the present invention after heat treatment is much improved compared with that of conventional welding wire (tensile strength of 400MPa, using traditional casting method and without composition optimization).

[0044] Table 1

[0045]

[0046] Example 2

[0047] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0048] (1) After the aluminum liquid is smelted, it is poured into the casting tank to begin casting, while positive pressure electromagnetic stirring is applied (the stirring power can reach 70W / t); the mass percentage of the composition of the smelted aluminum liquid is shown in the table below:

[0049]

[0050] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0051] (3) The aluminum rod after continuous casting is trapezoidal. High frequency heating and resistance heating are turned on. The machine display temperature is 410℃ and the actual temperature is 398℃. After 7 rolling processes, a wire rod with a diameter of 8.0mm is obtained.

[0052] (4) After the wire rod is homogenized and annealed at 510℃ for 8 hours, it is rough drawn 4 times to obtain a wire of 3.0 mm. Then it is recrystallized and annealed at 500℃ for 10 hours, and then it can be cold-processed into finished wire of Φ1.6 mm or Φ1.2 mm.

[0053] The tensile properties of the finished yarn were tested (using the same method as in Example 1), and the test results are shown in Table 2 below (where X, Y, and Z represent the three directions, using the left-hand rule; X1-X3, Y1-Y3, and Z1-Z3 are the results of three tests in the X, Y, and Z directions). The table shows that the finished yarn not only exhibited improved tensile strength but also more uniform mechanical properties in the X, Y, and Z directions.

[0054] Table 2

[0055]

[0056] Comparative Example 1

[0057] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0058] (1) After the aluminum liquid is smelted, it is poured into the casting tank to begin casting, while positive pressure electromagnetic stirring is applied (the stirring power can reach 70W / t); the mass percentage of the composition of the smelted aluminum liquid is shown in the table below:

[0059]

[0060] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0061] (3) The aluminum rod after continuous casting is trapezoidal. High frequency heating and resistance heating are turned on. The machine display temperature is 400℃ and the actual temperature is 394℃. After 7 rolling processes, a wire rod with a diameter of 7.0mm is obtained.

[0062] (4) After the wire rod is homogenized and annealed at 500℃ for 8 hours, it is rough drawn 4 times to obtain a wire of 3.0 mm. Then it is recrystallized and annealed at 500℃ for 10 hours, and then it can be cold-processed into finished wire of Φ1.6 mm or Φ1.2 mm.

[0063] The tensile properties of the finished yarn were tested (using the same method as in Example 1), and the test results are shown in Table 3 below. (Where X, Y, and Z represent three directions, using the left-hand rule, X1-X3, Y1-Y3, and Z1-Z3 are the results of three tests in the X, Y, and Z directions.)

[0064] Table 3

[0065]

[0066] Comparative Example 1 and Example 1 used the same preparation process, except that Y was replaced with Yb. The results showed that the tensile strength of Comparative Example 1 was lower than that of Example 1, indicating that the synergistic refining effect of Sc and Y was better.

[0067] Comparative Example 2

[0068] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0069] (1) After the aluminum liquid is smelted, it is poured into the casting tank to begin casting, while positive pressure electromagnetic stirring is applied (the stirring power can reach 70W / t); the mass percentage of the composition of the smelted aluminum liquid is shown in the table below:

[0070]

[0071] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0072] (3) The aluminum rod after continuous casting is trapezoidal. When high-frequency heating and resistance heating are turned on, the machine-displayed temperature is 400℃, and the actual temperature is 395℃. During continuous rolling, the casting cannot pass through the mold, resulting in extreme thermal cracking and deformation stress (e.g. Figure 5 (As shown). The reason is that Zn has a low melting point, while Sc and Y have much higher melting points. During the smelting process, Zn will melt very early, which may lead to uneven distribution of Zn. In addition, the low-melting-point eutectic phase formed after the addition of Zn will soften during the rolling process, resulting in a decrease in the overall strength of the material and increasing the difficulty of rolling. On the other hand, these eutectic phases, distributed in a network or continuous manner in the matrix, will hinder dislocation movement, resulting in a decrease in the plastic deformation capacity of the material and making it prone to cracks or fractures.

[0073] Comparative Example 3

[0074] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0075] (1) After the aluminum liquid is smelted, it is poured into the casting tank to begin casting, while positive pressure electromagnetic stirring is applied (the stirring power can reach 70W / t); the mass percentage of the composition of the smelted aluminum liquid is shown in the table below:

[0076]

[0077] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0078] (3) The aluminum rod after continuous casting is trapezoidal. High frequency heating and resistance heating are turned on. The machine display temperature is 410℃ and the actual temperature is 399℃. After 7 rolling processes, a wire rod with a diameter of 7.0mm is obtained.

[0079] (4) After the wire rod is homogenized and annealed at 500℃ for 8 hours, it is rough drawn 4 times to obtain a wire of 3.0 mm. Then it is recrystallized and annealed at 500℃ for 10 hours, and then it can be cold-processed into finished wire of Φ1.6 mm or Φ1.2 mm.

[0080] The tensile properties of the finished yarn were tested (the test method is the same as in Example 1), and the test results are shown in Table 4 below (where X, Y, and Z are three directions, left-hand rule, X1-X3, Y1-Y3, and Z1-Z3 are the three test results in the X, Y, and Z directions).

[0081] Table 4

[0082]

[0083] Based on tensile strength results, the grain refinement effect is weaker when Sc is less than 0.3% compared to 0.3%-0.5%.

[0084] Comparative Example 4

[0085] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0086] (1) After the aluminum liquid is smelted, it is poured into the casting tank and casting begins. At the same time, positive pressure electromagnetic stirring is applied (the stirring power can reach 70W / t). The mass percentage of the components of the smelted aluminum liquid is shown in the table below.

[0087]

[0088] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0089] (3) The aluminum rod after continuous casting is trapezoidal. High frequency heating and resistance heating are turned on. The machine display temperature is 410℃ and the actual temperature is 402℃. After 7 rolling passes, a wire rod with a diameter of 7.0mm is obtained.

[0090] (4) After the wire rod is homogenized and annealed at 500℃ for 8 hours, it is rough drawn 4 times to obtain a wire of 3.0 mm. Then it is recrystallized and annealed at 500℃ for 10 hours, and then it can be cold-processed into finished wire of Φ1.6 mm or Φ1.2 mm.

[0091] The tensile properties of the finished yarn were tested (the test method is the same as in Example 1), and the test results are shown in Table 5 below (where X, Y, and Z are three directions, left-hand rule, X1-X3, Y1-Y3, and Z1-Z3 are the three test results in the X, Y, and Z directions).

[0092] Table 5

[0093]

[0094] From the tensile test results, adding too much Y will form a large precipitate, resulting in coarse grain size and decreased performance.

[0095] Comparative Example 5

[0096] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0097] (1) After the aluminum liquid is smelted, it is poured into the casting tank and a positive pressure electromagnetic stirring is applied at the same time (the stirring power can reach 70W / t); the mass percentage of the components of the smelted aluminum liquid is shown in the table below.

[0098]

[0099] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0100] (3) The aluminum rods produced by continuous casting are trapezoidal. With high-frequency heating and resistance heating activated, the machine-displayed temperature is 360℃, while the actual temperature is 353℃. At this temperature, the casting is difficult to pass through the rolling mill, making smooth production impossible. Figure 6 As shown.

[0101] Comparative Example 6

[0102] A high-strength 2319 aluminum alloy welding wire, the preparation method of which includes the following steps:

[0103] (1) After the aluminum liquid is smelted, it is poured into the casting tank and a positive pressure electromagnetic stirring is applied at the same time (the stirring power can reach 70W / t); the mass percentage of the components of the smelted aluminum liquid is shown in the table below.

[0104]

[0105] (2) When the aluminum liquid in the waiting channel reaches the cooling steel belt, turn on the three-way water cooling, with water flow rates of 18L / min, 15L / min and 12L / min respectively;

[0106] (3) The aluminum rod after continuous casting is trapezoidal. High frequency heating and resistance heating are turned on. The machine display temperature is 430℃ and the actual temperature is 427℃. After 7 rolling processes, a wire rod with a diameter of 7.0mm is obtained.

[0107] (4) After the wire rod is homogenized and annealed at 490℃ for 6 hours, it is rough drawn 4 times to obtain a wire of 3.0 mm. Then it is recrystallized and annealed at 490℃ for 8 hours, and then it can be cold-processed into finished wire of Φ1.6 mm or Φ1.2 mm.

[0108] The tensile properties of the finished yarn were tested (the test method is the same as in Example 1), and the test results are shown in Table 6 below (where X, Y, and Z are three directions, left-hand rule, X1-X3, Y1-Y3, and Z1-Z3 are the three test results in the X, Y, and Z directions).

[0109] Table 6

[0110]

[0111] From the tensile test results, the excessively high initial rolling temperature led to excessive grain growth, which in turn reduced the mechanical properties.

[0112] We also observed the metallographic structure of continuously cast and rolled wire rods, such as... Figure 7 As can be seen, its grains are relatively coarse.

[0113] In summary, this invention, through the synergistic effect of precisely controlling the aluminum liquid alloy composition system and optimizing the process, not only ensures the feasibility of continuous production but also ensures that the final product meets the performance requirements of the application.

[0114] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a high-strength 2319 aluminum alloy welding wire, characterized in that, Includes the following steps: (1) Smelting of aluminum liquid; The mass percentage of the composition of the smelted aluminum liquid is as follows: Cu 5.6-6.4, Fe 0.05-0.10, Mn 0.1-0.4, Si 0.02-0.12, Zr 0.15-0.30, Mg 0.005-0.015, Ti 0.1-0.2, V 0.03-0.15, Sc 0.3-0.5, Y 0.05-0.20, with the balance being Al; (2) Continuous casting: When the molten aluminum enters the flow channel, positive pressure electromagnetic stirring is applied; when the molten aluminum reaches the cooling steel strip, water cooling is turned on; (3) Continuous rolling: After the casting is heated, it is rolled; (4) Wire rod processing: The wire rod is subjected to the first heat treatment, rough drawing, second heat treatment, cold working and welding wire in sequence; The specific stirring power of the positive pressure electromagnetic stirrer mentioned in step (2) is 70-150W / t.

2. The method for preparing high-strength 2319 aluminum alloy welding wire as described in claim 1, characterized in that, The water cooling in step (2) includes three water cooling channels, with the water flow rate controlled at 10~20L / min and decreasing sequentially.

3. The method for preparing high-strength 2319 aluminum alloy welding wire as described in claim 1, characterized in that, The heating in step (3) uses high-frequency heating and resistance heating; the heating is to heat the surface and interior of the casting to a temperature of 370-410℃.

4. The method for preparing high-strength 2319 aluminum alloy welding wire as described in claim 1, characterized in that, The first heat treatment mentioned in step (4) is 500-530℃×8h.

5. The method for preparing high-strength 2319 aluminum alloy welding wire as described in claim 1, characterized in that, The second heat treatment mentioned in step (4) is 500-530℃×10h.

6. The method for preparing high-strength 2319 aluminum alloy welding wire as described in claim 1, characterized in that, The mass percentage composition of the molten aluminum after smelting in step (1) is as follows: Cu 6.1-6.3, Fe 0.05-0.06, Mn 0.23-0.27, Si 0.05, Zr 0.19-0.21, Mg 0.007-0.012, Ti 0.14-0.15, V 0.08-0.10, Sc 0.40-0.45, Y 0.12-0.13, with the balance being Al.

7. A high-strength 2319 aluminum alloy welding wire prepared by the method according to any one of claims 1-6.

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