A single-stage aging heat treatment process for 7050 aluminum alloy

Abstract

This invention provides a single-stage aging heat treatment process for 7050 aluminum alloy. The process involves homogenization heat treatment of round ingots, with a heating rate ≤45℃ / hour. The first-stage holding temperature is 450-470℃, and the holding time is 8-12 hours. The second-stage holding temperature is 467-480℃, and the holding time is 20-26 hours. After the second-stage holding, the ingot is furnace cooled to below 100℃. Cooling treatment is then performed by installing a standing wave water cooling device and a water-penetrating cooling device at the front beam outlet of the extruder, ensuring that the length of the extruded aluminum alloy product in water is ≥2.0m. Artificial peak aging is then performed, with a holding temperature of 170-190℃ and a holding time of 10-12 hours. Using this process, production costs can be effectively reduced and the production cycle shortened. The obtained 7050 aluminum alloy extruded products have a tensile strength ≥503MPa, a yield strength ≥434MPa, an elongation ≥7%, and a stress corrosion susceptibility factor ≤220.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy production, in particular to a single-stage aging heat treatment production process of 7050 aluminum alloy. BACKGROUND

[0002] The main alloying elements of 7050 aluminum alloy are Zn, Mg and Cu. This series of aluminum alloys are widely used in aerospace and industrial fields after extrusion, heat treatment and machining due to their low density, good formability and high specific strength. When used in the aerospace field, the comprehensive performance of corrosion and strength is strictly required, so off-line quenching + overaging process is usually used for production. When used in general industrial fields, there is no special requirement for corrosion performance, but the strength is strictly required, so the over-peak aging state T74 or T4511 state is usually used.

[0003] 7050 aluminum alloy has high deformation resistance during extrusion, which causes difficulties in extrusion and low production efficiency. To improve the above problems, the traditional technical route is to use a heat treatment furnace for solid solution heat treatment and artificial aging treatment after extrusion to obtain a product with corresponding performance. For products used in general industrial fields, there is no special requirement for corrosion performance, so the traditional technology produces excess products. In addition, the off-line quenching process and two-stage overaging in the traditional technical route result in high production cost and long production cycle.

[0004] Therefore, it is of great significance to provide a low-cost and short-cycle production process for general industrial 7050 aluminum alloy. SUMMARY

[0005] To overcome the above shortcomings of the prior art, the present application provides a single-stage aging heat treatment production process of 7050 aluminum alloy, which comprises alloy composition ratio, round ingot uniform heat treatment, extrusion treatment, cooling treatment, stretching treatment and artificial aging. The production process can effectively reduce the production cost and shorten the production cycle. The tensile strength of the obtained 7050 aluminum alloy extrusion product is ≥503 MPa, the yield strength is ≥434 MPa, the elongation is ≥7%, and the stress corrosion sensitivity factor is ≤220.

[0006] The technical scheme of the present application is as follows:

[0007] A single-stage aging heat treatment production process of 7050 aluminum alloy, comprising round ingot uniform heat treatment, cooling treatment and artificial over-peak aging.

[0008] The round ingot homogenization heat treatment has a temperature rising speed of ≤45℃ / h, a first-stage temperature of 450-470℃, a first-stage temperature holding time of 8-12h, a second-stage temperature of 467-480℃, a second-stage temperature holding time of 20-26h, and a cooling to ≤100℃ after the second-stage temperature holding; the homogenization treatment process makes the eutectic phase and most of the alloy strengthening original colors of the obtained aluminum alloy product to be dissolved into the aluminum matrix, thereby playing a strengthening role and improving the strength;

[0009] The cooling treatment is provided with a standing wave water cooling device and a water passing cooling device at the exit of the extrusion machine beam, so that the length of the extruded aluminum alloy product in water is ≥2.0m; the setting can cool the extruded aluminum alloy product to room temperature in a short time; the standing wave water cooling device can increase the water level height to form a water wall; the water passing cooling device is used to cool the product by passing through the water wall; the aluminum alloy is kept at a constant temperature in the high-temperature single-phase zone, and is rapidly cooled, so that the excess phase is fully dissolved into the solid solution, the various phases in the alloy are fully dissolved, the solid solution is strengthened, and the strength, hardness and corrosion resistance of the alloy are improved;

[0010] The artificial over-peak aging has a temperature holding time of 10-12h at a temperature of 170-190℃; the artificial over-peak aging promotes the formation of a large number of dispersed GP zones in the supersaturated solid solution as the core for the transition to the intermediate phase, the GP zones continue to grow to obtain the intermediate phase with a higher density, and the stress corrosion resistance of the alloy is improved.

[0011] Preferably, in the round ingot homogenization heat treatment, the temperature rising speed is 43℃ / h, the first-stage temperature holding temperature is 460℃, and the first-stage temperature holding time is 8h; the second-stage temperature holding temperature is 475℃, and the second-stage temperature holding time is 24h; after the second-stage temperature holding, the temperature is cooled to ≤100℃; the cooling is performed by air cooling, the air flow of the air cooling process is determined according to whether the round ingot produces cooling cracks, and the temperature holding start time is determined according to the temperature of the metal surface.

[0012] Preferably, in the cooling treatment, the water temperature of the standing wave water cooling device and the water passing cooling device is ≤50℃.

[0013] Preferably, in the artificial over-peak aging, the temperature holding temperature is 175℃, and the temperature holding time is 10h, so that the material precipitation strengthening potential can be maximized.

[0014] Preferably, the above-mentioned 7050 aluminum alloy single-stage aging heat treatment production process further comprises alloy component proportioning, extrusion treatment and stretching treatment.

[0015] Preferably, the alloy component proportioning selects a round ingot as a raw material, and the round ingot comprises the following elements in percentage by weight:

[0016] Si≤0.10%, Fe≤0.15%, Cu 2.1-2.6%, Mn≤0.10%, Mg 2.1-2.6%, Cr≤0.02%, Zn 6.0-6.7%, Ti≤0.06%, Zr 0.10-0.13%, balance Al and inevitable impurities; wherein the inevitable impurities are not more than 0.05% individually and not more than 0.15% in total.

[0017] Preferably, the extrusion treatment is performed in a reverse extrusion manner, the temperature of the die is 400-440 DEG C, the temperature of the extrusion cylinder is 390-420 DEG C, the temperature of the round ingot before extrusion is 390-420 DEG C, the product extrusion speed is 1.30-2.00 m / min, and the surface temperature of the metal before entering the cooling water is 410-450 DEG C.

[0018] Preferably, in the extrusion treatment, the temperature of the die is 420 DEG C, the temperature of the extrusion cylinder is 400 DEG C, the temperature of the round ingot before extrusion is 410 DEG C, the product extrusion speed is 1.40 m / min, and the surface temperature of the metal before entering the cooling water is 425 DEG C.

[0019] Preferably, in the stretching treatment, the cooled product is subjected to a stretching deformation of 1.20-2.50% by the stretching machine, so as to reduce the internal residual stress of the product.

[0020] Preferably, in the stretching treatment, the cooled product is subjected to a stretching deformation of 1.8% by the stretching machine within 4 hours, so as to eliminate the straightness difference and the residual stress caused by the drawing and the cooling deformation to the maximum extent.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The aluminum alloy extruded product obtained by using the production process of the present application has a tensile strength ≥ 503 MPa, a yield strength ≥ 434 MPa, an elongation ≥ 7%, and a stress corrosion sensitivity factor ≤ 220.

[0023] 2. In the production process of the present application, through the round ingot homogenization heat treatment, the cooling treatment and the artificial over-peak aging, the production process of the present application can still ensure the tensile strength, the yield strength, the elongation and the stress corrosion sensitivity factor of the product under the premise of reducing the pre-stretching, the pre-sawing and the solid solution heat treatment compared with the traditional process.

[0024] 3. The production process provided by the present application uses a cooling device for cooling treatment, instead of the traditional offline quenching process, thereby effectively reducing the production cost. DETAILED DESCRIPTION

[0025] In order to make the person skilled in the art better understand the technical solutions in the present application, the technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0026] Embodiment 1

[0027] A single-stage aging heat treatment production process of 7050 aluminum alloy, the specific process is as follows:

[0028] (1) Alloy composition ratio:

[0029] A round ingot with a diameter of 320 mm is selected as the raw material, a direct-reading spectrometer is used to detect the alloy composition of the round ingot for extrusion, and the element composition in the round ingot is as follows:

[0030] Si 0.04%, Fe 0.06%, Cu 2.16%, Mn 0.004%, Mg 2.25%, Cr 0.015%, Zn 6.46%, Ti 0.047%, Zr 0.128%, the balance being Al and unavoidable impurities; wherein the single content of the unavoidable impurities does not exceed 0.05%, and the total content does not exceed 0.15%;

[0031] (2) Homogenization heat treatment of round ingot:

[0032] The round ingot of step (1) is subjected to homogenization heat treatment: the heating rate is 43℃ / hour, the first-stage holding temperature is 460℃, and the holding time is 8 hours; the second-stage holding temperature is 475℃, and the holding time is 24 hours; after the second-stage holding is completed, the furnace is cooled to below 100℃; air cooling is used to reduce the temperature, and the air volume is controlled to avoid cooling cracks on the surface of the round ingot;

[0033] (3) Extrusion treatment:

[0034] The diameter of the extrusion cylinder of the extruder is 330 mm, and a single-hole die is used for the die, so that the extrusion ratio is 25.8;

[0035] The reverse extrusion method is used to extrude a round bar with a diameter of 65 mm, the temperature of the die is 420℃, the temperature of the extrusion cylinder is 400℃, and the temperature of the round ingot before extrusion is 410℃; the product extrusion speed is 1.40 m / minute; the surface temperature of the metal before entering the cooling water is 425℃;

[0036] (4) Cooling treatment:

[0037] The standing wave water cooling device and the water cooling device are installed at the exit of the extruder beam, the length of the extruded aluminum alloy cylindrical rod in water is controlled to be 2.5 m, the water temperature of the standing wave water cooling device and the water cooling device is 40℃, and the surface temperature of the product after cooling is 30℃; the setting can cool the extruded aluminum alloy product to room temperature in a short time;

[0038] (5) Stretching treatment:

[0039] The product after cooling is stretched by a stretching machine within 4 hours to produce a stretching deformation of 1.8%, so as to eliminate the straightness difference and residual stress caused by traction and cooling deformation to the greatest extent;

[0040] (6) Artificial over-peak aging:

[0041] The product after stretching is artificially aged, the holding temperature is 175℃, the holding time is 10 hours, and the 7050 aluminum alloy rod with a diameter of 65 mm is obtained.

[0042] The 7050 aluminum alloy rod obtained in Example 1 is sampled for room temperature tensile property test, conductivity test, and stress corrosion sensitivity factor test, and the results are shown in Table 1.

[0043] Table 1 Detection results of 7050 rod (diameter 65 mm) after aging

[0044] Test No. Tensile strength (MPa) Yield strength (MPa) Elongation after break (%) Conductivity (Ms / m) Stress corrosion sensitivity factor Standard value Test No. 503 434 7 / ≤220 1 528 474 12.5 23.12 196.56 2 525 473 13.0 23.21 194.48 3 527 476 13.5 23.22 197.36 4 525 475 12.5 23.19 196.72

[0045] As can be seen from Table 1, the 7050 alloy rod with a diameter of 65 mm produced by the process of the application has a room temperature tensile strength of 523 MPa or more in T74511 state, which is 20 MPa or more higher than the standard value in the industry, and the stress corrosion sensitivity factor is less than 220.

[0046] Example 2

[0047] A single-stage aging heat treatment production process for 7050 aluminum alloy, the specific process is as follows:

[0048] (1) Alloy composition ratio:

[0049] A round ingot with a diameter of 410 mm is selected as the raw material, a direct-reading spectrometer is used to detect the alloy composition of the round ingot for extrusion, and the element composition in the round ingot is as follows:

[0050] Si 0.05%, Fe 0.07%, Cu 2.22%, Mn 0.006%, Mg 2.28%, Cr 0.015%, Zn 6.42%, Ti 0.05%, Zr 0.13%, and the balance is Al and unavoidable impurities; wherein, the single content of the unavoidable impurities is not more than 0.05%, and the total content is not more than 0.15%;

[0051] (2) Round ingot homogenization heat treatment:

[0052] The round ingot of step (1) is subjected to homogenization heat treatment: the heating rate is 45°C / hour, the first-stage holding temperature is 450°C, and the holding time is 10 hours; the second-stage holding temperature is 467°C, and the holding time is 20 hours; after the second-stage holding is completed, the furnace is cooled to below 100°C; air cooling is used to reduce the temperature, and the air volume is controlled to avoid cooling cracks on the surface of the round ingot;

[0053] (3) Extrusion treatment:

[0054] The diameter of the extrusion cylinder of the extruder is 420 mm, and a single-hole die is used for the die, so that the extrusion ratio is 31.36;

[0055] The reverse extrusion method is used to extrude a 75 mm round bar, the die heating temperature is 400°C, the extrusion cylinder temperature is 390°C, and the round ingot temperature before extrusion is 390°C; the product extrusion speed is 1.30 m / minute; the metal surface temperature before entering the cooling water is 410°C;

[0056] (4) Cooling treatment:

[0057] A standing wave water cooling device and a water cooling device are installed at the outlet of the extruder beam, the length of the extruded aluminum alloy product in water is controlled to be 4.5 m, the water temperature of the standing wave water cooling device and the water cooling device is 50°C, so that the surface temperature of the product after cooling is 30°C; this setting can cool the extruded aluminum alloy product to room temperature in a short time;

[0058] (5) Stretching treatment:

[0059] The product after cooling is stretched by 1.7% within 4 hours by a stretching machine to maximize the elimination of straightness difference and residual stress caused by traction and cooling deformation;

[0060] (6) Artificial peak value aging:

[0061] The stretched product is subjected to artificial aging, the holding temperature is 170°C, and the holding time is 11 hours, to obtain a 7050 aluminum alloy bar with a diameter of 75 mm.

[0062] The 7050 aluminum alloy bar obtained in Example 2 is sampled for room temperature tensile property test, conductivity test, and stress corrosion sensitivity factor test, and the results are shown in Table 2;

[0063] Table 2 Detection results of 7050 bar (diameter 75 mm) after aging

[0064] Tensile strength (MPa) Yield strength (MPa) Elongation after break (%) Conductivity (Ms / m) Stress corrosion sensitivity factor Standard value Test No. Tensile strength (MPa) 503 434 7 / ≤220 1 532 476 13 23.02 199.76 2 530 476 13.5 23.04 199.52 3 528 472 14.5 23.06 195.28 4 528 473 13 23.06 196.28

[0065] In combination with Table 2, the T74511 state room temperature tensile strength of the 7050 alloy rod with a diameter of 75 mm produced by the process can reach 523 MPa or more, which is 25 MPa or more higher than the standard value in the industry, and the stress corrosion sensitivity factor is less than 220.

[0066] Example 3

[0067] A single-stage aging heat treatment production process of 7050 aluminum alloy, the specific process is as follows:

[0068] (1) Alloy component ratio:

[0069] A round ingot with a diameter of 410 mm is selected as the raw material, a direct-reading spectrometer is used to detect the alloy components of the round ingot for extrusion, and the element composition in the round ingot is as follows:

[0070] Si 0.05%, Fe 0.07%, Cu 2.22%, Mn 0.006%, Mg 2.28%, Cr 0.015%, Zn 6.42%, Ti 0.05%, Zr 0.13%, the balance being Al and unavoidable impurities; wherein the single content of the unavoidable impurities is not more than 0.05%, and the total content is not more than 0.15%;

[0071] (2) Homogenization heat treatment of round ingot:

[0072] The round ingot of step (1) is subjected to homogenization heat treatment: the heating rate is 45 ℃ / h, the first-stage holding temperature is 450 ℃, and the holding time is 10 h; the second-stage holding temperature is 467 ℃, and the holding time is 20 h; after the second-stage holding is completed, the furnace is cooled to below 100 ℃; the cooling is performed by air cooling, and the air volume is controlled to avoid cooling cracks on the surface of the round ingot;

[0073] (3) Extrusion treatment:

[0074] The diameter of the extrusion cylinder of the extruder is selected to be 420 mm, and a three-hole die is used for the die, so that the extrusion ratio is 23.52;

[0075] The 50 mm round bar is extruded by reverse extrusion, the die heating temperature is 400 ℃, the extrusion cylinder temperature is 390 ℃, and the round ingot temperature before extrusion is 390 ℃; the product extrusion speed is 1.30 m / min; the metal surface temperature before entering the cooling water is 410 ℃;

[0076] (4) Cooling treatment:

[0077] The standing wave water cooling device and the water cooling device are installed at the exit of the extruder beam, the length of the extruded aluminum alloy product in water is controlled to be 4.5 m, the water temperature of the standing wave water cooling device and the water cooling device is 50℃, and the surface temperature of the product after cooling is 30℃; the setting can cool the extruded aluminum alloy product to room temperature in a short time;

[0078] (5) Stretching treatment:

[0079] The product after cooling is stretched by a stretching machine within 4 hours to produce a stretching deformation of 1.7%, so as to eliminate the straightness difference and residual stress caused by traction and cooling deformation to the greatest extent;

[0080] (6) Artificial over-peak aging:

[0081] The product after stretching is artificially aged, the holding temperature is 170℃, and the holding time is 11 hours, so as to obtain the 7050 aluminum alloy rod with a diameter of 50 mm.

[0082] The 7050 aluminum alloy rod obtained in Example 2 is sampled to perform a room temperature tensile property test, an electrical conductivity test, and a stress corrosion sensitivity factor test, and the results are shown in Table 3.

[0083] Table 3 Detection results of the 7050 rod (diameter 50 mm) after aging

[0084] Yield strength (MPa) Elongation after break (%) Conductivity (Ms / m) Stress corrosion sensitivity factor Standard value Test No. Tensile strength (MPa) Yield strength (MPa) 503 434 7 / ≤220 1 536 477 12 23.1 199.8 2 535 476 13 23.12 198.56 3 532 473 12 23.11 195.68 4 533 473 13 23.1 195.8

[0085] It can be known from Table 3 that the 7050 alloy rod with a diameter of 50 mm produced by the process of the present application has a room temperature tensile strength of 532 MPa or more in T7451 state, which is higher than the standard value in the industry by 25 MPa or more, and the stress corrosion sensitivity factor is less than 220.

[0086] Comparative Example 1

[0087] The traditional production process is as follows:

[0088] (1) Alloy component proportioning:

[0089] A round ingot with a diameter of 410 mm is selected as a raw material, a direct-reading spectrometer is used to detect the alloy components of the round ingot for extrusion, and the element composition of the round ingot is as follows:

[0090] Si 0.04%, Fe 0.06%, Cu 2.16%, Mn 0.004%, Mg 2.25%, Cr 0.015%, Zn 6.46%, Ti 0.047%, Zr 0.128%, and the balance is Al and unavoidable impurities; wherein, the single content of the unavoidable impurities is not more than 0.05%, and the total content is not more than 0.15%;

[0091] (2) Uniform heat treatment of round ingot:

[0092] The round ingot of step (1) is subjected to homogenization heat treatment: the temperature rising speed is 43°C / hour, the first stage temperature is 460°C, the temperature holding time is 8 hours; the second stage temperature is 475°C, the temperature holding time is 24 hours; after the second stage temperature holding is finished, the furnace is cooled to below 100°C;

[0093] (3) Extrusion treatment:

[0094] The diameter of the extrusion cylinder of the extruder is selected to be 420mm, and a single hole die is used for the die, so that the extrusion ratio is 31.36;

[0095] The reverse extrusion mode is used, the die heating temperature is 420°C, the extrusion cylinder temperature is 357-363°C, and the round ingot temperature before extrusion is 378-385°C; the product extrusion speed is 1.50-1.80m / minute;

[0096] (4) Pre-stretching treatment:

[0097] The product after extrusion is subjected to 0.3-1.0% stretching deformation by a stretching machine to eliminate the bending after extrusion and avoid the bending affecting the quenching out of the vertical quenching furnace;

[0098] (5) Pre-sawing treatment:

[0099] The product is subjected to interrupted sawing to ensure that the product length after sawing is shorter than the length of the vertical quenching furnace, so that the product can be smoothly loaded into the vertical quenching furnace;

[0100] (6) Solid solution heat treatment:

[0101] The interrupted product is subjected to solid solution heat treatment, the temperature holding temperature is 477±5°C, the temperature holding time is 210min, the quenching transfer time is ≤20s, and the cooling water temperature is ensured to be ≤50°C;

[0102] (7) Stretching treatment:

[0103] The product after solid solution heat treatment is subjected to 1.7% stretching deformation by a stretching machine within 4 hours to eliminate the straightness difference and residual stress caused by traction and cooling deformation to the greatest extent;

[0104] (8) Artificial gradient aging:

[0105] The product after stretching is subjected to artificial aging, the first stage temperature holding temperature is 121±5°C, the temperature holding time is 6 hours, the second stage temperature holding temperature is 177±5°C, and the temperature holding time is 10 hours.

[0106] The 7050 alloy after aging of Comparative Example 1 is sampled to perform room temperature tensile property test, conductivity test, and stress corrosion sensitivity factor test, and the results are shown in Table 4;

[0107] Table 4 Test results of 7050 alloy bar (diameter 75mm) after aging

[0108] Elongation after break (%) Conductivity (Ms / m) Stress corrosion sensitivity factor Standard value Test No. Tensile strength (MPa) Yield strength (MPa) Elongation after break (%) Conductivity (Ms / m) Stress corrosion sensitivity factor 1 545 490 14.0 23.61 206.68 2 542 486 14.5 23.67 201.96 3 540 488 14.5 23.55 205.4 4 545 490 15 23.60 206.8

[0109] In combination with Table 4, compared with the traditional process, the process of the present application can reduce the process route of pre-stretching, pre-sawing, solution heat treatment, etc., and the single-stage over-peak aging holding time is shorter than the double-stage aging, the production cycle is shortened, the production cost is effectively reduced, and the product reaches the qualified performance under the premise of reducing the process.

[0110] Although the present application has been described in detail by referring to preferred embodiments thereof, it is to be understood that the present application is not limited to these preferred embodiments. Rather, it can be embodied in many other forms without departing from the spirit thereof. Any modification or replacement made by those skilled in the art based on the technical concept disclosed in the present application shall fall within the scope of the present application. Any modification or replacement made by those skilled in the art based on the technical concept disclosed in the present application shall fall within the scope of the present application. Therefore, the scope of the present application should be defined by the scope of the claims.

Claims

1. A single-stage ageing heat treatment production process for a 7050 aluminium alloy, characterised in that, The alloy component proportioning, round ingot homogenizing heat treatment, extrusion treatment, cooling treatment, stretching treatment and artificial over-peak aging are included, and the specific steps are as follows: (1) Alloy component proportioning: round ingot is selected as raw material, and the round ingot includes the following elements with the weight percentage: Si≤0.10%, Fe≤0.15%, Cu 2.1-2.6%, Mn≤0.10%, Mg 2.1-2.6%, Cr≤0.02%, Zn 6.0-6.7%, Ti≤0.06%, Zr 0.10-0.13%, the balance of Al and inevitable impurities; wherein, the single content of inevitable impurities is not more than 0.05%, and the total content is not more than 0.15%; (2) Round ingot homogenizing heat treatment: the heating speed is ≤45℃ / hour, the first-stage temperature is 450-470℃, and the holding time is 8-12 hours; the second-stage temperature is 467-480℃, and the holding time is 20-26 hours; after the second-stage holding, the furnace is cooled to below 100℃; (3) Extrusion treatment: the reverse extrusion is adopted, the temperature of the die is 400-440℃, the temperature of the extrusion cylinder is 390-420℃, and the temperature of the round ingot before extrusion is 390-420℃; the product extrusion speed is 1.30-2.00m / minute; the metal surface temperature before entering the cooling water is 410-450℃; (4) Cooling treatment: the standing wave water cooling device and the water cooling device are installed at the exit of the extruder beam, so that the length of the extruded aluminum alloy product in water is ≥2.0m; (5) Stretching treatment: the product after cooling is stretched by the stretching machine to produce 1.20-2.50% of the stretching deformation; (6) Artificial over-peak aging: the holding temperature is 170-190℃, and the holding time is 10-12 hours.

2. The single-stage thermal aging heat treatment production process of 7050 aluminum alloy according to claim 1, wherein, In the round ingot homogenizing heat treatment, the heating speed is 43℃ / hour, the first-stage temperature is 460℃, and the holding time is 8 hours; the second-stage temperature is 475℃, and the holding time is 24 hours; after the second-stage holding, the furnace is cooled to below 100℃.

3. The single-stage thermal aging heat treatment production process of 7050 aluminum alloy according to claim 2, wherein, In the cooling treatment, the water temperature of the standing wave water cooling device and the water cooling device is ≤50℃.

4. The single-step thermal aging production process for a 7050 aluminum alloy according to claim 3, wherein In the artificial over-peak aging, the holding temperature is 175℃, and the holding time is 10 hours.

5. The single-stage thermal aging heat treatment production process of 7050 aluminum alloy according to claim 1, wherein, In the extrusion treatment, the temperature of the die is 420℃, the temperature of the extrusion cylinder is 400℃, and the temperature of the round ingot before extrusion is 410℃; the product extrusion speed is 1.40m / minute; the metal surface temperature before entering the cooling water is 425℃.

6. The single-stage thermal aging production process for 7050 aluminum alloys as claimed in claim 1, wherein, In the stretching treatment, the product after cooling is stretched by the stretching machine to produce 1.8% of the stretching deformation within 4 hours.