Preparation method and application of wire special for nano TiC modified 7-series aluminum alloy electric arc additive

Abstract

The invention discloses a preparation method and application of a wire special for nano TiC modified 7-series aluminum alloy electric arc additive, and belongs to the technical field of metal additive manufacturing, and the preparation method comprises the following steps that S1, an alloy solution is obtained; s2, a dispersing agent is added to form suspension liquid, the suspension liquid is added into the alloy solution, and primary ultrasonic treatment and secondary ultrasonic treatment are carried out; s3, the casting solution is subjected to semi-continuous casting, and a cast ingot is obtained; s4, the cast ingot is subjected to two-section type homogenizing heat treatment, and a homogenized cast ingot is formed; s5, the homogenized cast ingot is sawn into sections and scalped, the cast ingot is put into an extruding machine to be subjected to extrusion machining, an extruded wire is formed, and extrusion machining comprises first-pass extrusion and second-pass extrusion; and S6, multiple times of warm drawing and annealing are conducted, then mechanical milling, ultrasonic cleaning and passivating treatment are conducted, a special wire is formed, and the high-strength and low-defect wire component is prepared through the formed special wire through the dispersing-forming-material increasing three-dimensional synergistic technology.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing technology, specifically to a method for preparing and applying a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire. Background Technology

[0002] Arc-wire additive manufacturing technology for aluminum alloys boasts high efficiency and low cost, offering significant advantages in the fabrication of large-scale flexible structures and holding broad application prospects in the aerospace field. With the increasing demand for lightweight structures and high-strength aluminum alloys, the need for arc-wire additive manufacturing technology for 7-series ultra-high-strength aluminum alloys is becoming increasingly urgent. Currently, research on laser additive manufacturing of 7-series aluminum alloy powder is relatively abundant, and preliminary additive manufacturing using various types of 7-series aluminum alloys has been achieved through selective laser deposition. However, research and application of arc-wire additive manufacturing for 7-series aluminum alloy wires are still in their early stages. This is mainly constrained by the following factors:

[0003] (1) Prominent metallurgical defects: 7-series aluminum alloys contain high levels of Zn, Mg, and Cu, with element loss rate > 40% during arc additive manufacturing, and high density of hot cracks and high porosity.

[0004] (2) Processing and forming difficulties: 7-series aluminum alloys have a high work hardening rate, and conventional extrusion-drawing is prone to cracking. Complex heat treatment is required, which is costly and inefficient. Specifically, the traditional drawing process yields less than 60% of the finished product, and the heat treatment involves multiple stages of solution aging.

[0005] (3) Significant performance anisotropy: The longitudinal and transverse tensile strength of additive components produced by traditional CMT process differs by more than 20%, and the elongation fluctuates by more than 50%, which cannot meet the uniformity requirements of load-bearing structures.

[0006] (4) Bottleneck of nano-modification: When adding nanoparticles in the existing technology, the particle dispersion uniformity is poor due to agglomeration. In particular, the agglomeration rate is >30%, which not only fails to refine the grains, but also introduces heterogeneous defects, such as unfused nanoparticles such as TiC, Al4O3, etc.

[0007] CN116144993A discloses a 7-series aluminum alloy wire for arc additive manufacturing, its preparation method, and its application. This method achieves ultra-high strength 7-series aluminum alloy wire for arc additive manufacturing by optimizing the content of the main alloying elements Zn, Mg, and Cu, and utilizing micro-alloying treatment with elements such as Ti, Zr, and Sc. This ensures both ultra-high strength and good resistance to hot cracking. However, the addition of alloying elements during wire preparation increases the smelting step, easily introducing other impurity elements. Even small amounts of trace elements show significant burn-off under the arc, easily leading to performance degradation. The burn-off rate of alloying elements at the high temperature of the arc is >40%, limiting the actual strengthening effect. The addition of multiple elements makes it difficult to control smelting impurities, with Fe and Si impurities easily forming brittle phases. Furthermore, the problem of work hardening of the wire remains unsolved, relying on complex heat treatment, resulting in high production costs.

[0008] In view of this, this invention addresses the aforementioned core pain points by proposing an integrated technical solution of "precise dispersion of nanoparticles + gradient forming process + synergistic control of additive parameters," which breaks through the technical bottleneck of 7-series aluminum alloy arc additive manufacturing. Its innovation and technical effect are significantly different from existing technologies. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to achieve the preparation of high-strength, low-defect wire components by forming special wires through a three-dimensional collaborative process of "dispersion-forming-additive manufacturing".

[0010] The technical solution adopted by this invention to solve the technical problem is as follows: a method for preparing a special wire for arc additive manufacturing of nano-TiC modified 7-series aluminum alloy, comprising the following steps:

[0011] S1: Melt pure aluminum ingots and add Cu-Al master alloy, Zn and Mg pure metal in sequence to obtain alloy melt;

[0012] S2: TiC nanoparticles are mixed with sodium citrate and added to an ethanol solution to form a mixed ethanol solution. The mixed ethanol solution is stirred to form a suspension. The suspension is added to the alloy solution and subjected to a first-stage ultrasonic treatment and a second-stage ultrasonic treatment to form a casting solution. The first-stage ultrasonic treatment is performed at 10 kHz and 1.8-2.2 kW power for 4-6 min, and the second-stage ultrasonic treatment is performed at 20 kHz and 2.0-2.5 kW power for 12-18 min.

[0013] S3: The casting solution is subjected to semi-continuous casting to obtain an ingot;

[0014] S4: Perform a two-stage homogenization heat treatment on the ingot to form a homogenized ingot;

[0015] S5: The homogenized ingot is sawn into segments, peeled, and placed into an extruder for extrusion processing to form extruded filaments;

[0016] S6: The extruded filament is subjected to multiple warm drawing forming processes, and annealing is performed after each warm drawing forming process to form a warm drawn filament. The warm drawn filament is then subjected to mechanical milling, ultrasonic cleaning, and passivation treatment to form the special filament.

[0017] As a preferred technical solution of the present invention, step S1 specifically includes the following steps:

[0018] S1.1: The pure aluminum ingot is melted at a temperature of 730℃-770℃;

[0019] S1.2: Add Cu-Al master alloy and hold at this temperature for 25-35 minutes;

[0020] S1.3: Add pure Zn and Mg metals and stir for 9-11 minutes;

[0021] S1.4: Obtain the alloy solution.

[0022] As a preferred embodiment of the present invention, the TiC nanoparticles have a diameter range of 55-75 nm and a weight percentage range of 1.4-1.6 wt.%, the sodium citrate has a weight percentage range of 0.1-0.3 wt.%, the stirring speed ranges of 2800-3200 r / min, and the stirring time ranges of 25 min-35 min.

[0023] As a preferred embodiment of the present invention, the semi-continuous casting has a casting temperature range of 750℃-770℃, a billet pulling speed range of 60-68mm / min, a cooling water flow rate range of 85-95L / min, and a cooling rate ≥110℃ / s.

[0024] As a preferred embodiment of the present invention, the diameter of the ingot is in the range of 110mm-130mm.

[0025] As a preferred embodiment of the present invention, the two-stage homogenization heat treatment of the ingot in step S4 specifically includes:

[0026] The ingot is held at 460-470℃ for 10-12 hours, then at 420-430℃ for 10-12 hours, and then cooled to room temperature to perform the two-stage homogenization heat treatment.

[0027] As a preferred embodiment of the present invention, the extrusion process includes a first extrusion and a second extrusion. The first extrusion has an extrusion temperature range of 390-410℃ and a speed range of 0.6-0.9 mm / s, forming a rod with a diameter range of 9.0-10.0 mm. The second extrusion has an extrusion temperature range of 345-355℃ and a speed range of 2.2-2.8 mm / s, so that the rod forms the extruded filament with a diameter range of 2.6-2.8 mm.

[0028] As a preferred embodiment of the present invention, step S6 specifically includes the following steps:

[0029] S6.1: The extruded filament is subjected to a first warm drawing forming treatment at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 2.6-2.8mm to 1.9-2.1mm. Then, a first annealing is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min.

[0030] S6.2: The extruded filament after the first annealing is subjected to a second warm drawing process at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 1.9-2.1mm to 1.4-1.6mm. Then, a second annealing is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min.

[0031] S6.3: The extruded filament after the second annealing is subjected to a third warm drawing process at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 1.4-1.6mm to 1.1-1.3mm. Then, a third annealing process is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min to form the warm-drawn filament.

[0032] S6.4, The thermally drawn filament is subjected to mechanical milling, ultrasonic cleaning, and passivation treatment to form the special filament.

[0033] As a preferred embodiment of the present invention, the special wire contains Zn with a mass percentage ranging from 6.5% to 7.8%, Mg with a mass percentage ranging from 2.3% to 2.5%, Cu with a mass percentage ranging from 1.5% to 1.7%, TiC with a mass percentage ranging from 1.4% to 1.6%, Fe with a mass percentage ranging from ≤0.10%, Si with a mass percentage ranging from ≤0.07%, and the balance being Al.

[0034] A method for using a special filament prepared by the above-described method for arc additive manufacturing includes the following steps:

[0035] S1: Using a cold metal transition deposition method, the special wire is used as the filler material for arc additive manufacturing. During the arc additive manufacturing process, the current range of the cold metal transition deposition is 125-135A, the voltage range is 12.0-12.6V, the wire feeding speed range is 6.5-9.5m / min, the protective gas used is 99.999% argon, and the flow rate of the protective gas is 20-24L / min.

[0036] S2: Interlayer cooling is performed during the cold metal transition deposition process, wherein the interlayer cooling is carried out by forced air cooling and the interlayer temperature range is controlled by infrared thermometry to be 55-75℃.

[0037] S3: The aluminum alloy deposit is obtained after the electric arc additive manufacturing.

[0038] The beneficial effects of this invention are reflected in:

[0039] 1. By using sodium citrate as a dispersant, and controlling the diameter range of nanoparticles and the weight ratio of the dispersant, two ultrasonic treatments are used to reduce the problem of poor particle dispersion uniformity caused by agglomeration when adding nanoparticles in the traditional way. This achieves single-particle dispersion of nanoparticles with uniform particle spacing and reduces heterogeneous defects.

[0040] 2. Based on two ultrasonic treatments, a two-stage homogenization heat treatment method is adopted, combined with corresponding temperature and time control, which improves the interfacial bonding strength between nanoparticles and aluminum matrix. Compared with the traditional ultrasonic dispersion method, the interfacial bonding strength is increased by 40%.

[0041] 3. By combining two extrusion processes with three warm drawing treatments and a single warm drawing followed by annealing, the final special filament achieves a surface roughness Ra≤0.8μm, a significant improvement compared to the traditional Ra≥1.5μm; tensile strength of 280-350MPa; elongation of 9-15%, a significant improvement compared to the traditional process elongation <7%; and a filament yield of over 70%, a significant improvement compared to the traditional process <60%, without the need for subsequent complex heat treatment, reducing process costs by 35%.

[0042] 4. Pure metals are used as components of the alloy solution, and Cu-Al master alloy, Zn, and Mg pure metals are selected to reduce the situation where elements easily evaporate and form brittle phases at high temperatures.

[0043] 5. By using forced air cooling between layers and temperature control through infrared thermography, the additive components are free of thermal cracks, have a porosity of <0.2% (compared to >2.0% in traditional processes), a longitudinal tensile strength of 510-540MPa, a transverse tensile strength of 500-550MPa, and an anisotropy ratio of ≤1.04 (≤1.05 for forgings). Attached Figure Description

[0044] Figure 1 These are TEM micrographs illustrating the transition layer of this invention;

[0045] Figure 2 This is a schematic diagram illustrating the gradient extrusion achieved through two extrusion processes in this invention;

[0046] Figure 3 This is a schematic diagram of the additive manufacturing component of the present invention;

[0047] Figure 4 This is a schematic diagram of the metallographic structure of the additive component of the present invention;

[0048] Figure 5 This is a schematic diagram of the process for preparing the filament material according to the present invention. Detailed Implementation

[0049] The invention will now be described in further detail with reference to the accompanying drawings.

[0050] Combined with appendix Figure 1-5 As shown, a method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire includes the following steps:

[0051] S1: Melt pure aluminum ingots and add Cu-Al master alloy, Zn and Mg pure metal in sequence to obtain alloy melt;

[0052] Specifically:

[0053] S1.1: The pure aluminum ingot is melted at a temperature of 730℃-770℃;

[0054] S1.2: Add Cu-Al master alloy and hold at this temperature for 25-35 minutes;

[0055] S1.3: Add pure Zn and Mg metals and stir for 9-11 minutes;

[0056] S1.4: Obtain the alloy solution;

[0057] S2: TiC nanoparticles are mixed with sodium citrate and added to an ethanol solution to form a mixed ethanol solution. The mixed ethanol solution is stirred to form a suspension. Specifically, the diameter of the TiC nanoparticles ranges from 55 to 75 nm, and the weight percentage ranges from 1.4 to 1.6 wt.%. The weight percentage of the sodium citrate ranges from 0.1 to 0.3 wt.%. The stirring speed ranges from 2800 to 3200 r / min, preferably 3000 r / min. The stirring time ranges from 25 to 35 min, preferably 30 min, to form a stable suspension and avoid initial agglomeration of TiC nanoparticles. The suspension is added to the alloy solution and subjected to a first-stage ultrasonic treatment and a second-stage ultrasonic treatment to form a casting solution. The first-stage ultrasonic treatment is performed at 10 kHz and 1.8-2.2 kW power for 4-6 min to break up large agglomerates. The second-stage ultrasonic treatment is performed at 20 kHz and 2.0-2.5 kW power for 12-18 min to achieve dispersion of TiC single particles.

[0058] S3: The casting solution is subjected to semi-continuous casting to obtain an ingot, wherein the casting temperature range of the semi-continuous casting is 750℃-770℃, the billet pulling speed range is 60-68mm / min, the cooling water flow rate range is 85-95L / min, the cooling rate is ≥110℃ / s, and the ingot diameter range is 110mm-130mm.

[0059] S4: The ingot is subjected to a two-stage homogenization heat treatment to form a homogenized ingot. The ingot is held at 460-470℃ for 10-12 hours. Preferably, the ingot is held at 470℃ for 12 hours and then at 420-430℃ for 10-12 hours. Preferably, it is held at 430℃ for 10 hours. Then it is cooled to room temperature to perform the two-stage homogenization heat treatment. The thickness of the Al4C3 transition layer at the interface between TiC and the aluminum matrix is ​​controlled to be 2.2-2.8 nm to avoid the problems of easy embrittlement and weak bonding caused by excessively thin transition layers, and to improve the cooperative stress-bearing capacity between particles and the matrix.

[0060] By performing first-stage and second-stage ultrasonic treatment on the suspension, the ingot is subjected to two-stage homogenization heat treatment, resulting in a TiC agglomeration rate of <5%, uniform particle spacing with a spacing range of 600-800nm, and a 40% improvement in interfacial bonding strength compared to traditional ultrasonic dispersion.

[0061] S5: The homogenized ingot is sawn into segments, peeled, and placed in an extrusion press for extrusion processing to form extruded wire. Specifically, the extrusion processing includes a first extrusion and a second extrusion. The first extrusion has an extrusion temperature range of 390-410℃ and a speed range of 0.6-0.9 mm / s, forming rods with a diameter range of 9.0-10.0 mm. The high temperature of the first extrusion triggers dynamic recrystallization, refining the grains to 50-80 μm to reduce the basis of work hardening. The second extrusion has an extrusion temperature range of 345-355℃ and a speed range of 2.2-2.8 mm / s, forming the extruded wire with a diameter range of 2.6-2.8 mm. The dislocation density (10) is controlled at a medium temperature. 13 -10 14 m -2 This helps prevent cracking caused by dislocation buildup.

[0062] S6: The extruded filament is subjected to multiple warm drawing forming processes, and annealing is performed after each warm drawing forming process to form a warm drawn filament. The single-pass section shrinkage rate is 25-30%. The internal stress is released by annealing. The warm drawn filament is then subjected to mechanical milling, ultrasonic cleaning, and passivation to form the special filament.

[0063] Specifically:

[0064] S6.1: The extruded filament is subjected to a first warm drawing forming treatment at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 2.6-2.8mm to 1.9-2.1mm. Then, a first annealing is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min.

[0065] S6.2: The extruded filament after the first annealing is subjected to a second warm drawing process at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 1.9-2.1mm to 1.4-1.6mm. Then, a second annealing is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min.

[0066] S6.3: The extruded filament after the second annealing is subjected to a third warm drawing process at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 1.4-1.6mm to 1.1-1.3mm. Then, a third annealing process is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min to form the warm-drawn filament.

[0067] S6.4, The thermally drawn filament is subjected to mechanical milling, ultrasonic cleaning, and passivation treatment to form the special filament;

[0068] The special filament contains Zn at a mass ratio of 6.5-7.8%, Mg at a mass ratio of 2.3-2.5%, Cu at a mass ratio of 1.5-1.7%, TiC at a mass ratio of 1.4-1.6%, Fe at a mass ratio of ≤0.10%, and Si at a mass ratio of ≤0.07%, with the balance being Al. The surface roughness Ra of the special filament is ≤0.8μm (compared to Ra≥1.5μm in traditional processes), the tensile strength is 280-350MPa, and the elongation is 9-15% (compared to <7% in traditional processes). Furthermore, the yield of the special filament is increased to over 70% (compared to <60% in traditional processes), eliminating the need for complex subsequent heat treatment and reducing process costs by 35%.

[0069] A method for using a special filament prepared by the above-described method for arc additive manufacturing includes the following steps:

[0070] S1: Using a cold metal transition deposition method, the special wire is used as the filler material for arc additive manufacturing. During the arc additive manufacturing process, the current range of the cold metal transition deposition is 125-135A, the voltage range is 12.0-12.6V, the wire feeding speed range is 6.5-9.5m / min, the protective gas used is 99.999% argon, and the flow rate of the protective gas is 20-24L / min.

[0071] S2: Interlayer cooling is performed during the cold metal transition deposition process. The interlayer cooling is carried out by forced air cooling. Infrared temperature measurement is used to control the interlayer temperature range to 55-75℃. The temperature range is controlled at 55-75℃ to avoid weak bonding when the temperature is <50℃ and heat accumulation when the temperature is >80℃.

[0072] S3: An aluminum alloy deposit is obtained after the electric arc additive manufacturing process;

[0073] The additive components formed by the aluminum alloy deposits are free from hot cracks, have a porosity of <0.2% (compared to >2.0% in traditional processes), a longitudinal tensile strength of 510-540 MPa, a transverse tensile strength of 500-550 MPa, and an anisotropy ratio of ≤1.04 (≤1.05 for forgings).

[0074]

[0075] Table 1 shows the composition and mechanism of action of the special filament material.

[0076]

[0077]

[0078] Table 2. Schematic diagram of mechanical properties of additive components in various directions.

[0079] Taking the preparation of TiC with an agglomeration rate of 4.2%, an interface Al4C3 thickness of 2.5 nm, and a grain size of 65 μm (ingot) → 35 μm (wire) as an example:

[0080] S1: Melt pure aluminum ingots and add Cu-Al master alloy, Zn and Mg pure metal in sequence to obtain alloy melt;

[0081] Specifically:

[0082] S1.1: The pure aluminum ingot is melted at a temperature of 750°C;

[0083] S1.2: Add Cu-Al master alloy and hold at that temperature for 30 minutes;

[0084] S1.3: Add pure Zn and Mg metals and stir for 10 minutes;

[0085] S1.4: Obtain the alloy solution;

[0086] S2: TiC nanoparticles are mixed with sodium citrate and added to an ethanol solution to form a mixed ethanol solution. The mixed ethanol solution is stirred to form a suspension. Specifically, the diameter of the TiC nanoparticles is 55-75 nm and the weight percentage is 1.5 wt.%, the weight percentage of the sodium citrate is 0.2 wt.%, the stirring speed is 3000 r / min, and the stirring time is 30 min. The suspension is added to the alloy solution and subjected to a first-stage ultrasonic treatment and a second-stage ultrasonic treatment to form a casting solution. The first-stage ultrasonic treatment is performed at 10 kHz and 2.0 kW power for 5 min, and the second-stage ultrasonic treatment is performed at 20 kHz and 2.2 kW power for 15 min.

[0087] S3: The casting solution is subjected to semi-continuous casting to obtain an ingot, wherein the casting temperature of the semi-continuous casting is 760℃, the billet pulling speed is 65mm / min, the cooling water flow rate is 90L / min, the cooling rate is 120℃ / s, and the diameter of the ingot is 120mm.

[0088] S4: The ingot is subjected to a two-stage homogenization heat treatment to form a homogenized ingot. The ingot is held at 470°C for 12 hours and then at 430°C for 12 hours, and then cooled to room temperature to perform the two-stage homogenization heat treatment.

[0089] S5: The homogenized ingot is sawn into segments, peeled, and placed into an extruder for extrusion processing to form extruded wire. Specifically, the extrusion processing includes a first extrusion and a second extrusion. The first extrusion is performed at a temperature of 400°C and a speed of 0.8 mm / s to form a rod with a diameter of 9.5 mm. The second extrusion is performed at a temperature of 350°C and a speed of 2.5 mm / s to form the extruded wire with a diameter of 2.7 mm.

[0090] S6: The extruded filament is subjected to multiple warm drawing forming processes, and annealing is performed after each warm drawing forming process to form a warm drawn filament. The warm drawn filament is then subjected to mechanical milling, ultrasonic cleaning, and passivation to form the special filament.

[0091] Specifically:

[0092] S6.1: The extruded filament is subjected to a first warm drawing forming treatment at a temperature of 230°C, so that the diameter of the extruded filament is drawn from 2.7 mm to 2.0 mm. Then, a first annealing is performed at a temperature of 150°C for 30 min.

[0093] S6.2: The extruded filament after the first annealing is subjected to a second warm drawing process at a temperature of 230°C, so that the diameter of the extruded filament is drawn from 2.0 mm to 1.5 mm. Then, a second annealing is performed at a temperature of 150°C for 30 min.

[0094] S6.3: The extruded filament after the second annealing is subjected to a third warm drawing process at a temperature of 230°C, so that the diameter of the extruded filament is drawn from 1.5 mm to 1.2 mm. Then, a third annealing is performed at a temperature of 150°C for 30 minutes to form the warm drawn filament.

[0095] S6.4, The thermally drawn filament is subjected to mechanical milling, ultrasonic cleaning, and passivation treatment to form the special filament;

[0096] The special wire has a tensile strength of 302 MPa, an elongation of 13.2%, a TiC agglomeration rate of 4.2%, an interface Al4C3 thickness of 2.5 nm, and a grain size of 65 μm (ingot) → 35 μm (wire).

[0097] Taking the additive manufacturing of an additive component with no thermal cracks and a porosity of 0.18% using the aforementioned special filament as an example:

[0098] Includes the following steps:

[0099] S1: Using a cold metal transition deposition method, arc additive manufacturing is performed with the special wire as the filler material. During the arc additive manufacturing process, the equipment parameters for cold metal transition deposition are as follows: Fnix CMT Advanced 4000 power supply, current of 130A, voltage of 12.4V, wire feeding speed of 8m / min, protective gas of 99.999% argon, and flow rate of the protective gas of 22L / min.

[0100] S2: Interlayer cooling is performed during the cold metal transition deposition process, wherein the interlayer cooling is carried out by forced air cooling and the interlayer temperature is controlled at 65°C by infrared thermometry.

[0101] S3: An aluminum alloy deposit is obtained after the electric arc additive manufacturing process;

[0102] Among them, the results of aluminum alloy additive components are as follows:

[0103] Microscopic results: equiaxed crystals (length-to-diameter ratio 1.1:1), grain size 32 μm;

[0104] Mechanical properties: tensile strength 522 MPa, transverse strength 515 MPa, anisotropy ratio 1.01, elongation 12.3%;

[0105] Defects: No hot cracks, porosity 0.18%.

[0106] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a special wire for arc additive manufacturing of nano-TiC modified 7-series aluminum alloy, characterized in that: Includes the following steps: S1: Melt pure aluminum ingots and add Cu-Al master alloy, Zn and Mg pure metal in sequence to obtain alloy melt; S2: TiC nanoparticles are mixed with sodium citrate and added to an ethanol solution to form a mixed ethanol solution. The mixed ethanol solution is stirred to form a suspension. The suspension is added to the alloy solution and subjected to a first-stage ultrasonic treatment and a second-stage ultrasonic treatment to form a casting solution. The first-stage ultrasonic treatment is performed at 10 kHz and 1.8-2.2 kW power for 4-6 min, and the second-stage ultrasonic treatment is performed at 20 kHz and 2.0-2.5 kW power for 12-18 min. S3: The casting solution is subjected to semi-continuous casting to obtain an ingot; S4: Perform a two-stage homogenization heat treatment on the ingot to form a homogenized ingot; S5: The homogenized ingot is sawn into segments, peeled, and placed into an extruder for extrusion processing to form extruded filaments; S6: The extruded filament is subjected to multiple warm drawing forming processes, and annealing is performed after each warm drawing forming process to form a warm drawn filament. The warm drawn filament is then subjected to mechanical milling, ultrasonic cleaning, and passivation treatment to form the special filament.

2. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 1, characterized in that: S1 specifically includes the following steps: S1.1: The pure aluminum ingot is melted at a temperature of 730℃-770℃; S1.2: Add Cu-Al master alloy and hold at this temperature for 25-35 minutes; S1.3: Add pure Zn and Mg metals and stir for 9-11 minutes; S1.4: Obtain the alloy solution.

3. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 1, characterized in that: The TiC nanoparticles have a diameter range of 55-75 nm and a weight percentage range of 1.4-1.6 wt.%, the sodium citrate has a weight percentage range of 0.1-0.3 wt.%, the stirring speed ranges of 2800-3200 r / min, and the stirring time ranges of 25 min-35 min.

4. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 1, characterized in that: The semi-continuous casting process has a casting temperature range of 750℃-770℃, a billet pulling speed range of 60-68mm / min, a cooling water flow rate range of 85-95L / min, and a cooling rate ≥110℃ / s.

5. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 1, characterized in that: The diameter of the ingot is in the range of 110mm-130mm.

6. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 1, characterized in that: The two-stage homogenization heat treatment of the ingot in step S4 specifically includes: The ingot is held at 460-470℃ for 10-12 hours, then at 420-430℃ for 10-12 hours, and then cooled to room temperature to perform the two-stage homogenization heat treatment.

7. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 5, characterized in that: The extrusion process includes a first extrusion and a second extrusion. The first extrusion has an extrusion temperature range of 390-410℃ and a speed range of 0.6-0.9 mm / s, forming a rod with a diameter range of 9.0-10.0 mm. The second extrusion has an extrusion temperature range of 345-355℃ and a speed range of 2.2-2.8 mm / s, so that the rod forms the extruded wire with a diameter range of 2.6-2.8 mm.

8. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 7, characterized in that: S6 specifically includes the following steps: S6.1: The extruded filament is subjected to a first warm drawing forming treatment at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 2.6-2.8mm to 1.9-2.1mm. Then, a first annealing is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min. S6.2: The extruded filament after the first annealing is subjected to a second warm drawing process at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 1.9-2.1mm to 1.4-1.6mm. Then, a second annealing is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min. S6.3: The extruded filament after the second annealing is subjected to a third warm drawing process at a temperature range of 220-240℃, so that the diameter of the extruded filament is drawn from 1.4-1.6mm to 1.1-1.3mm. Then, a third annealing process is performed at a temperature range of 140℃-160℃ for a time range of 28min-32min to form the warm-drawn filament. S6.4, The thermally drawn filament is subjected to mechanical milling, ultrasonic cleaning, and passivation treatment to form the special filament.

9. The method for preparing a nano-TiC modified 7-series aluminum alloy arc additive manufacturing wire according to claim 1, characterized in that: The special wire material contains Zn with a mass percentage ranging from 6.5% to 7.8%, Mg with a mass percentage ranging from 2.3% to 2.5%, Cu with a mass percentage ranging from 1.5% to 1.7%, TiC with a mass percentage ranging from 1.4% to 1.6%, Fe with a mass percentage ranging from ≤0.10%, Si with a mass percentage ranging from ≤0.07%, and the balance being Al.

10. A method for arc additive manufacturing using a special filament prepared according to any one of claims 1-9, comprising the following steps, characterized in that: S1: Using a cold metal transition deposition method, the special wire is used as the filler material for arc additive manufacturing. During the arc additive manufacturing process, the current range of the cold metal transition deposition is 125-135A, the voltage range is 12.0-12.6V, the wire feeding speed range is 6.5-9.5m / min, the protective gas used is 99.999% argon, and the flow rate of the protective gas is 20-24L / min. S2: Interlayer cooling is performed during the cold metal transition deposition process, wherein the interlayer cooling is carried out by forced air cooling and the interlayer temperature range is controlled by infrared thermometry to be 55-75℃. S3: The aluminum alloy deposit is obtained after the electric arc additive manufacturing.

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