An impact-resistant aluminum alloy material for aerospace and its preparation method

Abstract

The present invention belongs to the field of alloy materials, and particularly relates to an impact-resistant aluminum alloy material for aerospace and its preparation method. The purpose of the present invention is to invent and create a new type of third-generation aluminum-lithium alloy through composition design and process innovation, which is produced by continuous casting and rolling process, to increase the types of continuously cast and rolled aluminum alloy rods, and to provide a new option for aluminum alloy materials used in aerospace. Through the continuous and efficient production method of continuous casting and rolling, it promotes the rapid development of the aluminum-lithium alloy industry.

Description

Technical Field

[0001] The invention belongs to the field of alloy materials, and in particular relates to an impact-resistant aluminum alloy material for aerospace and a preparation method thereof. Background Art

[0002] In order to reduce deadweight and increase load-bearing capacity, aerospace uses a large amount of aluminum alloy materials. At present, 2 series and 7 series high-strength aluminum alloys are mainly used. In order to meet their strength, the quality of materials needs to be improved. During the processing of 2 series and 7 series aluminum alloys, due to the need for quenching and strengthening, the brittleness increases, which increases the failure rate during use. At present, the industry mainly manufactures 2 series and 7 series aluminum alloys with the production process of hot rolling + wire drawing annealing + quenching. Due to heating energy consumption and efficiency problems, hot rolling has low production efficiency. The new aluminum-lithium alloy has ultra-high strength and lighter weight, high specific strength, and has become the third-generation aluminum alloy material vigorously developed by various countries. It has broad development prospects in the future. However, due to the high manufacturing difficulty of aluminum-lithium alloys due to the active lithium alloy, the manufacturing production volume in the industry is very small. Due to its processing difficulty, the development of its materials is limited. The present invention uses a new intermediate alloy addition method to overcome the problem of active oxidation of lithium elements during casting, and uses a new ladle seal to add intermediate active metals to achieve continuous casting and rolling production of third-generation aluminum-lithium alloy products and processes. The tensile strength of its products can reach over 650MPa, which is higher than the 170MPa of the current 7075 aluminum alloy used in aerospace.

[0003] Due to the high manufacturing difficulty of aluminum-lithium alloys due to the high activity of lithium alloys, the manufacturing production volume in the industry is very small. Due to its processing difficulty, the development of its materials is limited. At present, the industry uses vacuum melting and subsequent processing to manufacture aluminum-lithium alloy plates, but its yield rate is less than 50%. Some industries use plasma jet forming, and its process manufacturing efficiency is low, which is not suitable for large-scale product use. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing an impact-resistant aluminum alloy material for aerospace, comprising the following steps:

[0005] S1: melting the aluminum alloy, adding aluminum-boron alloy to react, adding sodium-removing refining agent, refining, and obtaining aluminum liquid A;

[0006] S2: heating the aluminum liquid B, adding lithium for secondary alloying after online refinement, and obtaining aluminum liquid C; the secondary alloying is performed in an online alloying turbulent flow ladle; the online refinement is performed by mixing the heated aluminum liquid B and aluminum-titanium-boron alloy, and then adding the mixture to the online alloying turbulent flow ladle;

[0007] S3: Heat up the aluminum liquid B, refine it online, remove impurities, and then add lithium for secondary alloying to obtain aluminum liquid C. The secondary alloying is carried out in an online alloying turbulent ladle. The method of online refining is to mix the heated aluminum liquid B with aluminum-titanium-boron alloy.

[0008] S4: Cast the aluminum liquid C, roll it, and perform homogenization annealing to obtain a homogenized aluminum alloy material.

[0009] S5: Draw the homogenized aluminum alloy material and perform a recovery treatment to obtain the impact-resistant aluminum alloy material for aerospace use.

[0010] Furthermore, in the step S1, the purity of the aluminum alloy is not less than 99.90%.

[0011] Furthermore, in the step S2, heat up to 780 - 800 °C.

[0012] Furthermore, in the step S2, the content of the sodium removal refining agent is 2 kg / 1000 kg of aluminum liquid B.

[0013] Furthermore, in the step S2, the addition method of the sodium removal refining agent is to blow the sodium removal particulate refining agent into it by using argon gas, and the blowing speed is greater than 1.5 kg / min.

[0014] Furthermore, in the step S2, the method of impurity removal is as follows: Let it stand for 60 min, then remove the aluminum slag on the upper part of the aluminum liquid by blowing argon gas. After standing for 180 min, transfer the aluminum liquid to the casting furnace by means of hydraulic tilting. Note that the aluminum discharge port must be at the upper part in the middle of the furnace molten pool to avoid pouring out the furnace bottom and the upper aluminum liquid during pouring, thereby ensuring the purity of the transferred aluminum liquid.

[0015] Furthermore, in the step S3, heat up to 800 - 840 °C.

[0016] The present invention adopts secondary online continuous alloying: Continuously add extremely active alloys at the ladle to avoid alloy oxidation.

[0017] Furthermore, in the step S3, the method of impurity removal is online degassing and online filtration.

[0018] The design of the online alloying turbulent ladle structure can achieve online alloying. A turbulent plate is designed at the ladle outlet to avoid the generation of turbulence in the aluminum liquid in the ladle during casting, and liquid masses are generated due to the tumbling of the aluminum liquid during online alloying. The turbulent plate can achieve the effect of slag blocking.

[0019] Furthermore, in the step S4, the casting temperature is 708 - 720 °C, and the billet discharging temperature is 380 - 460 °C.

[0020] Further, in the step S4, during the rolling process, the inlet rolling temperature is 530 - 560 °C, and the final rolling temperature is 300 - 360 °C.

[0021] Specifically, in the step S4, during the rolling process, the billet is heated online for the second time to raise the temperature of the billet to 530 - 560 °C, and then enters the rolling mill for rolling deformation. When the final rolling temperature reaches 300 - 360 °C, it is deformed into a round rod, and then it is wound into a coil.

[0022] Further, in the step S4, the specific operation of homogenization annealing is as follows: cool down to room temperature (25 ± 5 °C), heat up to 180 - 220 °C, and keep the temperature for 5 - 7 h; heat up to 350 - 370 °C, and keep the temperature for 15 - 18 h; heat up to 480 - 500 °C, keep the temperature for 78 - 82 h, and then cool down to 90 - 110 °C.

[0023] Specifically, in the step S4, the specific operation of homogenization annealing is as follows: put the round rod into a nitrogen - filled oven for homogenization annealing. Heat it up at a rate of 3 °C / min to 200 °C, keep the temperature for 6 h, then use a vacuum pump to extract the air in the oven until it reaches - 0.1 MPa, and then fill it with nitrogen until it reaches 0 MPa. Heat the temperature up to 360 °C, keep the temperature for 16 h, then heat it up to 490 °C, keep the temperature for 80 h, and then let it cool down with the furnace. When cooling, use a vacuum pump to fill nitrogen at any time to keep the pressure in the furnace stable. After the temperature in the oven is lower than 100 °C, open the oven and take out the sample.

[0024] Further, in the step S5, the specific operation of drawing is as follows: subject the product after homogenization treatment to 4 - pass cold deformation with a compression of 15 - 25% per pass.

[0025] Further, in the step S5, the specific operation of recovery treatment is as follows: heat up at a rate of 2 - 4 °C / min to 260 - 300 °C, keep the temperature for 3 - 5 h; heat up to 430 - 440 °C, keep the temperature for 16 - 20 h, and cool down to 90 - 110 °C before secondary drawing.

[0026] Specifically, the specific operation of the recovery treatment is as follows: put the drawn wire into the oven, heat it up at a rate of 3 °C / min to 280 °C, keep the temperature for 4 h, then evacuate and fill the oven with nitrogen. Heat it up at the same rate to 435 °C, keep the temperature for 18 h, and then cool down with the furnace. When cooling, nitrogen should be replenished in a timely manner. After cooling to below 100 °C, open the furnace door, take out the wire, cool it down to room temperature, and then perform subsequent drawing. After drawing the wire to the specified size, carry out subsequent processing.

[0027] The present invention also provides an impact-resistant aluminum alloy material for aerospace prepared by the above preparation method, which is composed of the following components by weight percentage:

[0028] Si: 0.05 - 0.15%, Fe: 0.08 - 0.2%, Mn: 0.1 - 0.5%, Mg: 3.0 - 3.60%, Cu: 0.4 - 0.55%, Li: 1.3 - 1.7%, Sr: 0.05 - 0.10%, Be: 0.08 - 0.16% and Ti: 0.02 - 0.05%, and the balance is Al and other inevitable impurities.

[0029] The present invention also provides an aluminum alloy rivet or welding wire material for aerospace, including the impact-resistant aluminum alloy material for aerospace described in claim 9.

[0030] The technical solution of the present invention has the following advantages compared with the prior art:

[0031] 1. The technical solution of the present invention can realize the continuous casting and rolling production process of the third-generation aluminum-lithium alloy;

[0032] 2. The tensile strength of the processed material reaches more than 650 MPa, which can further reduce the material weight during aerospace use.

[0033] 3. Composition design: By adding Sc and Be elements and controlling their contents, the oxidation of Li elements is inhibited; after adding Mg and Cu elements, the alloy material has excellent vibration absorption performance and excellent subsequent processing performance.

[0034] 4. The present invention can ensure the uniform and stable internal structure of the material, eliminate casting processing defects, avoid abnormal grain growth, and ensure that there is no carbonized oil stain on the material surface through the multi-stage segmented normal-pressure nitrogen-charging heat treatment method. Description of the Drawings

[0035] Figure 1 It is the front view of the in-line alloying turbulent flow ladle.

[0036] Figure 2 It is the left view of the in-line alloying turbulent flow ladle.

[0037] Figure 3 It is the top view of the in-line alloying turbulent flow ladle.

[0038] Figure 4 It is the three-dimensional structure diagram of the in-line alloying turbulent flow ladle.

[0039] Figure 5 It is the three-dimensional structure schematic diagram of the in-line alloying turbulent flow ladle.

[0040] Explanation of the reference numerals: 1 - body, 2 - drainage groove, 3 - handrail. Specific Embodiments

[0041] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments cited are not intended to limit the present invention.

[0042] The following embodiments adopt an online alloying turbulent ladle, as Figure 4 shown, including a body 1, the body 1 is an arc-shaped open cylindrical structure, a drainage groove 2 is horizontally provided on an outer side surface at the top end of the body 1, and handrails 3 are provided at the upper ends of both side surfaces of the body 1 adjacent to the drainage groove 2.

[0043] The wire drawing process in the following embodiments is as follows: Recovery treatment Recovery treatment Example 1

[0044] (1) Melting: Put 99.90% aluminum ingots into a vertical melting furnace for melting. After the aluminum liquid is melted, add 5 kg of aluminum-boron alloy per ton of aluminum liquid to eliminate vanadium elements in the aluminum liquid. Then add a refining agent to the refining tank and stir evenly with high-purity nitrogen, and then let it stand for separation. After 24.2 h, when the impurities are fully separated, use a tilting furnace to transfer it to a primary alloying melting furnace.

[0045] (2) Primary alloying: Heat the high-purity aluminum liquid transferred from the melting furnace to 789 °C, and then add aluminum-silicon, aluminum-manganese, aluminum-copper, and aluminum-resistant alloys according to the alloy ratio. After adding, use electromagnetic stirring for 30 min, let it stand for 14 min after stirring, and then take a sample from each of the four directions in the furnace and measure the composition with a spectrometer. When the composition meets the requirements, use a magnesium adding device to press magnesium ingots into the aluminum liquid. After the magnesium ingots are melted, use electromagnetic stirring for 30 min, take a sample to detect the composition, and blow in sodium-removing particulate refining agent at a rate of 2.0 kg per ton of aluminum liquid at a blowing speed exceeding 1.5 kg / min. After the refining agent is blown in, let it stand for 59 min, and then remove the aluminum slag on the upper part of the aluminum liquid by blowing argon, and let it stand for 179 min.

[0046] (3) Purification: Transfer the aluminum liquid to the casting furnace by hydraulic tilting. Note that the aluminum discharge port must be in the upper middle part of the furnace melting pool to avoid pouring out the furnace bottom and upper aluminum liquid during pouring, thereby ensuring the purity of the transferred aluminum liquid.

[0047] (4) Casting: Heat the alloy liquid in the casting furnace to 825 °C, pour out the aluminum liquid by tilting the furnace, and then enter the online alloying turbulent ladle after online refinement, online degassing, and online filtration, as follows Figure 1, after adding lithium element by secondary alloying (feeding a lithium rod at a speed of 3.5 m per minute), it is poured into the crystallization wheel by the tangential vertex casting method, and the casting temperature is 715 °C. Control the rotation speed of the crystallization wheel and adjust the cooling water distribution to make the billet temperature 425 °C.

[0048] (5) Rolling: The billet is heated to 545 °C by online secondary heating, and then enters the rolling mill for rolling deformation. The final rolling temperature is 345 °C to deform it into a round rod, and then it is wound into a coil.

[0049] (6) Homogenization annealing: The finished product wound into a coil is put into a nitrogen-filled oven for homogenization annealing. It is heated at a heating rate of 3 °C / min to 200 °C, held at this temperature for 6 h, then the air in the oven is pumped out by a vacuum pump to -0.1 MPa, and then nitrogen is filled to 0 MPa. The temperature is raised to 360 °C, held for 16 h, then raised to 490 °C, held for 80 h, and then cooled in the furnace. During cooling, nitrogen is filled in time by a vacuum pump to keep the pressure in the furnace stable. After the temperature in the oven is lower than 100 °C, the oven is opened and the sample is taken out.

[0050] (7) Drawing: The homogenized product is cold deformed 4 times with a 20% reduction per pass, and then a recovery treatment is carried out. The recovered material is drawn according to the previous process.

[0051] (8) Recovery treatment: The drawn wire is put into the oven, heated to 280 °C at a heating rate of 3 °C / min, held for 4 h, then the oven is evacuated and filled with nitrogen, heated to 435 °C at the same heating rate, held for 18 h, and then cooled in the furnace. Nitrogen should be replenished in time during cooling. After cooling below 100 °C, the furnace door is opened, the wire is taken out and cooled to room temperature before subsequent drawing. The wire is drawn to the specified size and then subjected to subsequent processing to obtain the aluminum alloy material.

[0052] Example 2

[0053] The preparation method of Example 2 is the same as that of Example 1, except that the amount of added elements is different.

[0054] Example 3

[0055] The preparation method of Example 3 is the same as that of Example 1, except that the amount of added elements is different.

[0056] Example 4

[0057] (1) Melting: Put aluminum ingots with a purity of not less than 99.90% into a vertical melting furnace for melting. After the aluminum liquid melts, add an appropriate amount of aluminum-boron alloy to eliminate vanadium elements in the aluminum liquid. Then, add a refining agent to the refining tank and stir evenly with high-purity nitrogen, and then let it stand for separation. After 24 hours when the impurities are fully separated, use a tilting furnace to transfer it to a primary alloying melting furnace.

[0058] (2) Primary alloying: Heat the high-purity aluminum liquid transferred from the melting furnace to 780 - 800 °C, and then add aluminum-silicon, aluminum-manganese, aluminum-copper, aluminum-strontium alloy, and aluminum-beryllium alloy according to the alloy ratio. After adding, use electromagnetic stirring for 30 minutes, and let it stand for 15 minutes after stirring. Then, take a sample from each of the four directions in the furnace and use a spectrometer to measure the composition. If the composition meets the requirements, then use a magnesium feeder to press magnesium ingots into the aluminum liquid. After the magnesium ingots melt, use electromagnetic stirring for 30 minutes, take samples to detect the composition, and blow in sodium-removing particle refining agent at a rate of 2 kg of refining agent per ton of aluminum liquid using argon, with a blowing speed exceeding 1.5 kg / min. After blowing the refining agent, let it stand for 60 minutes, and then remove the aluminum slag on the upper part of the aluminum liquid by blowing argon, and let it stand for 180 minutes.

[0059] (3) Purification: Transfer the aluminum liquid to the casting furnace by hydraulic tilting. Note that the aluminum discharge port must be in the upper-middle part of the furnace melting pool to avoid pouring out the furnace bottom and upper aluminum liquid during pouring, thereby ensuring the purity of the transferred aluminum liquid.

[0060] (4) Casting: Heat the alloy liquid in the casting furnace to 800 - 840 °C, use the furnace to tilt and pour out the aluminum liquid, and then add aluminum-titanium-boron alloy after online refinement, online degassing, and online filtration, and enter the online alloying turbulent pouring ladle. Figure 1 , After adding lithium element through secondary alloying, pour it into the crystallizer by the tangential vertex casting method, and control the casting temperature between 708 - 720 °C. Control the rotation speed of the crystallizer and adjust the cooling water distribution to make the billet discharge temperature around 380 - 460 °C.

[0061] (5) Rolling: Heat the billet to 530 - 560 °C through online secondary heating, and then enter the rolling mill for rolling deformation. The final rolling temperature is 300 - 360 °C to deform it into round bars, and then wind and package them into coils.

[0062] (6) Homogenization annealing: Put the finished products packed in rolls into a nitrogen-filled oven for homogenization annealing. Heat at a rate of 2 - 4 °C / min to 180 - 220 °C, hold for 5 - 7 h, then use a vacuum pump to extract the air in the oven to -0.1 MPa, and then fill it with nitrogen to 0 MPa. Heat the temperature to 350 - 370 °C, hold for 15 - 18 h, and then heat it to 480 - 500 °C, hold for 78 - 82 h. Then let it cool in the furnace. During cooling, use a vacuum pump to fill nitrogen at any time to keep the pressure in the furnace stable. After the temperature in the oven is lower than 90 - 110 °C, open the oven and take out the samples.

[0063] (7) Drawing: Subject the homogenized product to 4 times of cold deformation with 20% compression per pass, and then perform a recovery treatment. Draw the material after the recovery treatment according to the previous process.

[0064] (8) Recovery treatment: Put the drawn wire into the oven, heat at a rate of 2 - 4 °C / min to 260 - 300 °C, hold for 3 - 5 h, then evacuate and fill the oven with nitrogen, heat at the same rate to 430 - 440 °C, hold for 16 - 20 h, and then cool in the furnace. During cooling, replenish nitrogen in a timely manner. After cooling to below 90 - 110 °C, open the furnace door, take out the wire, cool it to room temperature, and then perform subsequent drawing. Draw the wire to the specified size and then perform subsequent processing to obtain the aluminum alloy material.

[0065] Example 5

[0066] (1) Melting: Put 99.95% aluminum ingots into a vertical melting furnace for melting. After the aluminum liquid melts, add an appropriate amount of aluminum boron alloy to eliminate vanadium elements in the aluminum liquid. Then add a refining agent to the refining tank and stir evenly with high-purity nitrogen, and then let it stand for separation. After 24 h of sufficient separation of impurities, use a tilting furnace to transfer it to a primary alloying melting furnace.

[0067] (2) Primary alloying: Heat the high-purity aluminum liquid transferred from the melting furnace to 790 °C, and then add aluminum silicon, aluminum manganese, aluminum copper, aluminum strontium alloy, and aluminum beryllium alloy according to the alloy ratio. After adding, use electromagnetic stirring for 30 min, let it stand for 15 min after stirring, and then take a sample from each of the four directions in the furnace and use a spectrometer to measure the composition. If the composition meets the requirements, then use a magnesium feeder to press magnesium ingots into the aluminum liquid. After the magnesium ingots melt, use electromagnetic stirring for 30 min, take samples to detect the composition, and blow in sodium-removing particle refining agent at a rate of 2 kg of refining agent per ton of aluminum liquid with argon, and the blowing speed is 1.6 kg / min. After blowing the refining agent, let it stand for 60 min, and then remove the aluminum slag on the upper part of the aluminum liquid by blowing argon, and let it stand for 180 min.

[0068] (3) Purification: Transfer the molten aluminum to the casting furnace by means of hydraulic tilting. Note that the aluminum discharge port must be located at the upper part in the middle of the furnace bath to avoid pouring out the bottom and upper molten aluminum during tilting, thereby ensuring the purity of the transferred molten aluminum.

[0069] (4) Casting: Heat the alloy liquid in the casting furnace to 820 °C, pour out the molten aluminum by tilting the furnace, then add aluminum-titanium-boron alloy after online refinement, online degassing, and online filtration, and enter the online alloying turbulent pouring ladle. After adding lithium element through secondary alloying, pour it into the crystallizer by the tangential vertex casting method, and control the casting temperature between 712 °C. Control the rotation speed of the crystallizer and adjust the cooling water distribution to make the billet discharge temperature around 400 °C.

[0070] (5) Rolling: Raise the temperature of the billet to 550 °C through online secondary heating, then enter the rolling mill for rolling deformation, and deform it to the final rolling temperature of 330 °C to a round rod, and then wind it into a coil.

[0071] (6) Homogenization annealing: Put the coiled finished product into a nitrogen-filled oven for homogenization annealing. Heat it at a heating rate of 3 °C / min to 200 °C, hold for 6 h, then use a vacuum pump to evacuate the air in the oven to -0.1 MPa, and then fill it with nitrogen to 0 MPa. Heat the temperature to 360 °C, hold for 16 h, then heat it to 490 °C, hold for 80 h, and then let it cool with the furnace. During cooling, use a vacuum pump to fill nitrogen at any time to keep the pressure in the furnace stable. After the temperature in the oven is lower than 100 °C, open the oven and take out the sample.

[0072] (7) Drawing: Cold deform the homogenized product by 20% per pass for 4 times, and then perform a recovery treatment. Draw the material after the recovery treatment according to the previous process.

[0073] (8) Recovery treatment: Put the drawn wire into the oven, heat it at a heating rate of 3 °C / min to 280 °C, hold for 4 h, then evacuate and fill the oven with nitrogen, heat it at the same heating rate to 435 °C, hold for 18 h, and then cool with the furnace. During cooling, nitrogen should be replenished in time. After cooling to below 100 °C, open the furnace door, take out the wire, cool it to room temperature, and then perform subsequent drawing. Draw the wire to the specified size and then perform subsequent processing to obtain the aluminum alloy material.

[0074] Example 6

[0075] (1) Melting: Put 99.98% aluminum ingots into a vertical melting furnace for melting. After the aluminum liquid melts, add an appropriate amount of aluminum-boron alloy to eliminate vanadium elements in the aluminum liquid. Then, add a refining agent to the refining tank and stir evenly with high-purity nitrogen. After that, let it stand for separation. After 24 hours of sufficient impurity separation, use a tilting furnace to transfer it to a primary alloying melting furnace.

[0076] (2) Primary alloying: Heat the high-purity aluminum liquid transferred from the melting furnace to 780 °C, and then add aluminum-silicon, aluminum-manganese, aluminum-copper, aluminum-strontium alloy, and aluminum-beryllium alloy according to the alloy ratio. After adding, use electromagnetic stirring for 30 minutes. After stirring, let it stand for 15 minutes. Then, take a sample from each of the four directions in the furnace and use a spectrometer to measure the composition. If the composition meets the requirements, then use a magnesium feeder to press magnesium ingots into the aluminum liquid. After the magnesium ingots melt, use electromagnetic stirring for 30 minutes, take samples to detect the composition, and blow in sodium removal particulate refining agent at a rate of 2 kg of refining agent per ton of aluminum liquid using argon gas, with a blowing speed of 1.8 kg / min. After blowing the refining agent, let it stand for 60 minutes, and then remove the aluminum slag on the upper part of the aluminum liquid by blowing argon gas, and let it stand for 180 minutes.

[0077] (3) Purification: Transfer the aluminum liquid to the casting furnace by hydraulic tilting. Note that the aluminum discharge port must be in the upper-middle part of the furnace melting pool to avoid pouring out the furnace bottom and upper aluminum liquid during pouring, thereby ensuring the purity of the transferred aluminum liquid.

[0078] (4) Casting: Heat the alloy liquid in the casting furnace to 800 °C, pour out the aluminum liquid by tilting the furnace, and then add aluminum-titanium-boron alloy after online refinement, online degassing, and online filtration. Enter the online alloying turbulent pouring ladle, add lithium element through secondary alloying, and then pour it into the crystallization wheel by the tangential vertex casting method. The casting temperature is controlled between 708 °C. Control the rotation speed of the crystallization wheel and adjust the cooling water distribution to make the billet discharge temperature about 380 °C.

[0079] (5) Rolling: Raise the temperature of the billet to 530 °C through online secondary temperature increase, and then enter the rolling mill for rolling deformation. The final rolling temperature is 300 °C to deform it into a round rod, and then pack it into a coil.

[0080] (6) Homogenization annealing: Put the coiled finished product into a nitrogen-filled oven for homogenization annealing. Heat it at a heating rate of 2 °C / min to 180 °C, hold for 5 hours, then use a vacuum pump to evacuate the air in the oven to -0.1 MPa, and then fill it with nitrogen to 0 MPa. Raise the temperature to 350 °C, hold for 15 hours, then raise the temperature to 480 °C, hold for 78 hours, and then let it cool with the furnace. During cooling, use a vacuum pump to fill nitrogen at any time to keep the pressure in the furnace stable. After the temperature in the oven is lower than 90 °C, open the oven and take out the sample.

[0081] (7) Drawing: The homogenized product is cold deformed 4 times with a 20% compression per pass, and then a recovery treatment is carried out. The material after the recovery treatment is drawn according to the previous process.

[0082] (8) Recovery treatment: The drawn wire is put into an oven, heated to 260 °C at a heating rate of 2 °C / min, held for 3 h, then the oven is evacuated and filled with nitrogen, heated to 43 °C at the same heating rate, held for 16 h, and then cooled in the furnace. Nitrogen should be replenished in a timely manner during cooling. After cooling below 90 °C, the furnace door is opened, the wire is taken out and cooled to room temperature before subsequent drawing. The wire is drawn to the specified size and then processed subsequently to obtain the aluminum alloy material.

[0083] Example 7

[0084] (1) Melting: Put 99.99% aluminum ingots into a vertical melting furnace for melting. After the aluminum liquid melts, add an appropriate amount of aluminum-boron alloy to eliminate vanadium elements in the aluminum liquid. Then add a refining agent to the refining tank and stir evenly with high-purity nitrogen, and then let it stand for separation. After 24 h of full separation of impurities, use a tilting furnace to transfer it to a primary alloying melting furnace.

[0085] (2) Primary alloying: Heat the high-purity aluminum liquid transferred from the melting furnace to 800 °C, then add aluminum-silicon, aluminum-manganese, aluminum-copper, aluminum-strontium alloy, and aluminum-beryllium alloy according to the alloy ratio. After adding, stir with electromagnetic stirring for 30 min, let it stand for 15 min after stirring, then take a sample from each of the four directions in the furnace, measure the composition with a spectrometer. If the composition meets the requirements, then press magnesium ingots into the aluminum liquid using a magnesium addition device. After the magnesium ingots melt, stir with electromagnetic stirring for 30 min, take samples to detect the composition, and blow in sodium-removing particle refining agent at a rate of 2 kg per ton of aluminum liquid with argon at a blowing speed of 2.0 kg / min. After blowing the refining agent, let it stand for 60 min, and then remove the aluminum slag on the upper part of the aluminum liquid by blowing argon, and let it stand for 180 min.

[0086] (3) Purification: Transfer the aluminum liquid to the casting furnace by hydraulic tilting. Note that the aluminum discharge port must be in the upper-middle part of the furnace bath to avoid pouring out the bottom and upper aluminum liquid during pouring, thereby ensuring the purity of the transferred aluminum liquid.

[0087] (4) Casting: Heat the alloy liquid in the casting furnace to 840 °C, pour out the aluminum liquid by tilting the furnace, then add aluminum-titanium-boron alloy after online refinement, online degassing, and online filtration, enter the online alloying turbulent pouring ladle, add lithium element through secondary alloying, and then pour it into the crystallizer by the tangential vertex casting method. The casting temperature is controlled between 720 °C. Control the rotation speed of the crystallizer and adjust the cooling water distribution to make the billet discharge temperature about 460 °C.

[0088] (5) Rolling: The billet is heated to 560°C through online secondary temperature increase, and then enters the rolling mill for rolling deformation. The final rolling temperature is 360°C, and it is deformed into a round bar, and then it is wound into a coil.

[0089] (6) Homogenization annealing: The coiled finished product is put into a nitrogen-filled oven for homogenization annealing. It is heated at a rate of 4°C / min to 220°C, held for 7 hours, then the air in the oven is evacuated by a vacuum pump to -0.1 MPa, and then nitrogen is filled to 0 MPa. The temperature is raised to 370°C, held for 18 hours, then it is raised to 500°C, held for 82 hours, and then it is cooled in the furnace. During cooling, nitrogen is filled in time by the vacuum pump to keep the pressure in the furnace stable. After the temperature in the oven is lower than 110°C, the oven is opened and the sample is taken out.

[0090] (7) Drawing: The homogenized product is cold-deformed 4 times with a 20% reduction per pass, and then a recovery treatment is carried out. The material after the recovery treatment is drawn according to the previous process.

[0091] (8) Recovery treatment: The drawn wire is put into the oven and heated at a rate of 4°C / min to 300°C, held for 5 hours, then the oven is evacuated and filled with nitrogen, heated at the same rate to 440°C, held for 20 hours, and then cooled in the furnace. Nitrogen should be replenished in time during cooling. After cooling below 110°C, the furnace door is opened, the wire is taken out and cooled to room temperature before subsequent drawing. The wire is drawn to the specified size and then undergoes subsequent processing to obtain the aluminum alloy material.

[0092] Effect evaluation

[0093] Table 1 Elemental composition of the examples

[0094]

[0095] Table 2 Tensile strength test performance of the examples

[0096]

[0097] Vibration absorption performance test of aluminum alloy: Take a 40-mm-long sample, fix 10 cm of it, then apply a 50-N force to the other end which is suspended, and then release it instantly. Record the vibration time of the material. Repeat the experiment three times, and the results are shown in Table 3:

[0098] Table 3 Vibration absorption performance test results of aluminum alloy

[0099]

[0100] The average tensile strength of 7075 aluminum alloy of the same specification is 475 MPa, and the average vibration absorption performance is 2.65 s. The aluminum alloy material prepared by the present invention has a tensile strength of more than 650 MPa. Both its tensile strength and vibration absorption performance are higher than those of conventional aluminum alloy materials. When used in aerospace, this aluminum alloy material can further reduce the material weight.

[0101] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of an impact-resistant aluminum alloy material for aerospace, characterized in that It includes the following steps: S1: Melt the aluminum alloy, add aluminum-boron alloy for reaction, add sodium-removing refining agent, and refine to obtain aluminum liquid A; S2: After heating the aluminum liquid A, add aluminum-silicon alloy, aluminum-manganese alloy, aluminum-copper alloy, aluminum-strontium alloy, aluminum-beryllium alloy and magnesium. After mixing, add sodium-removing refining agent, conduct secondary refining and impurity removal to obtain aluminum liquid B; S3: Heat the aluminum liquid B, conduct on-line refinement, and add lithium for secondary alloying after impurity removal to obtain aluminum liquid C; the secondary alloying is carried out in an on-line alloying turbulent pouring ladle; the on-line refinement method is: mix the heated aluminum liquid B and aluminum-titanium-boron alloy; S4: Cast the aluminum liquid C, roll it, and conduct homogenization annealing to obtain a homogenized aluminum alloy material; S5: Draw the homogenized aluminum alloy material and conduct recovery treatment to obtain the impact-resistant aluminum alloy material for aerospace; The impact-resistant aluminum alloy material for aerospace is composed of the following components by weight percentage: Si: 0.05 - 0.15%, Fe: 0.08 - 0.2%, Mn: 0.1 - 0.5%, Mg: 3.0 - 3.60%, Cu: 0.4 - 0.55%, Li: 1.3 - 1.7%, Sr: 0.05 - 0.10%, Be: 0.08 - 0.16% and Ti: 0.02 - 0.05%, and the balance is Al and other inevitable impurities.

2. The preparation method according to claim 1, characterized in that, In the step S1, the purity of the aluminum alloy is not less than 99.90%.

3. The preparation method according to claim 1, characterized in that, In the step S2, heat it to 780 - 800 °C.

4. The preparation method according to claim 1, wherein In the step S3, heat it to 800 - 840 °C.

5. The preparation method according to claim 1, characterized in that, In the step S4, the casting temperature is 708 - 720 °C, and the billet discharging temperature is 380 - 460 °C.

6. The preparation method according to claim 1, characterized in that, In the step S4, during the rolling process, the rolling-in temperature is 530 - 560 °C, and the final rolling temperature is 300 - 360 °C.

7. The preparation method according to claim 1, characterized in that, In the step S4, the specific operation of the homogenization annealing is: cool it to room temperature, heat it to 180 - 220 °C, and keep it warm for 5 - 7 h; heat it to 350 - 370 °C, and keep it warm for 15 - 18 h; heat it to 480 - 500 °C, and keep it warm for 78 - 82 h and then cool it to 90 - 110 °C.

8. The preparation method according to claim 1, characterized in that, In the step S5, the specific operation of the recovery treatment is: heat it to 260 - 300 °C, and keep it warm for 3 - 5 h; heat it to 430 - 440 °C, and keep it warm for 16 - 20 h, and conduct secondary drawing after cooling it to 90 - 110 °C.

9. An aerospace impact-resistant aluminum alloy material prepared by the preparation method according to any one of claims 1-8, characterized in that, Composed of the following components by weight percentage Composition: Si: 0.05 - 0.15%, Fe: 0.08 - 0.2%, Mn: 0.1 - 0.5%, Mg: 3.0 - 3.60%, Cu: 0.4 - 0.55%, Li: 1.3 - 1.7%, Sr: 0.05 - 0.10%, Be: 0.08 - 0.16% and Ti: 0.02 - 0.05%, and the balance is Al and other inevitable impurities.

10. An aluminum alloy rivet or welding wire material for aerospace, characterized in that, It includes the impact-resistant aluminum alloy material for aerospace as described in claim 9.

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