A rolling process for eliminating flaw detection noise of high-strength aluminum alloy plate with low alloy content

Abstract

This invention provides a rolling process for eliminating noise during flaw detection of high-strength aluminum alloy sheets with low alloy content. The process employs a three-stage homogenization heat treatment: heating at 40℃ / h to 400-405℃ and holding for 3 hours; heating at 40℃ / h to 445-460℃ and holding for 10-24 hours; heating at 10℃ / h to 492-496℃ and holding for 8-24 hours; and then rolling at 420℃. The rolling process uses 9-15 passes, with the first three passes being rapid rolling and the last three passes using a large reduction (greater than 17% reduction per pass) for rapid rolling. The middle passes use a large reduction for rapid rolling, while the remaining passes use a small reduction for slow rolling. The final rolling temperature is not lower than 410℃. The thick plates obtained by this rolling process have a uniform microstructure along the thickness direction, small grain size, pass non-destructive testing, and possess high strength, plasticity, and fracture toughness.

Description

Technical Field

[0001] This invention relates to the field of aerospace aluminum thick plate production technology, specifically to a rolling process for eliminating flaw detection noise in low-alloy high-strength aluminum alloy plates. Background Technology

[0002] High-strength Al-Cu-Mg aluminum alloy thick plates are widely used in aerospace, aviation, and transportation fields due to their excellent heat resistance, high specific strength, corrosion resistance, and high fracture toughness. High-strength aluminum alloy thick plates require high fracture toughness and fatigue performance. High fracture toughness indicates a strong resistance to crack propagation, which is crucial for flight safety. Therefore, strict control of alloy element composition is necessary during production. In Al-Cu-Mg high-strength aluminum alloy thick plates, a Mn content exceeding 0.50% will refine the Al grain size. 20 The Cu2Mn3 phase aggregates and grows, which makes the alloy sensitive to quenching. This easily leads to problems such as coarse grains and uneven microstructure at different thickness locations. As a result, this type of thick plate cannot meet the development trend of long service life, high speed and large size of aerospace products.

[0003] To address the issue of uneven microstructure along the thickness of high-strength aluminum alloy thick plates, a rolling method with large reduction and strong deformation is employed to improve the penetration capability of the rolling process. However, this strong deformation increases the deformation stress of the material, leading to increased rolling energy consumption and the aggregation and growth of recrystallized grains, resulting in coarse grains and failure to pass flaw detection. Multi-pass rolling can achieve fine grains and effectively solve the flaw detection failure problem; however, due to the small deformation amount and the fact that the rolling deformation is mainly concentrated at the edge of the plate thickness, the deformation degree in the center of the plate is small, resulting in insufficient deformation in the core and significant differences in the microstructure, thus causing uneven microstructure. Therefore, the above two solutions generally cannot simultaneously solve the problems of uneven microstructure and coarse grains. To address the above problems of coarse grains and uneven microstructure, a method of large reduction in the first few rolling passes followed by a shutdown to allow the plate to cool down before rolling, or a method of small deformation and multiple passes, can theoretically solve the above problems. However, small deformation and multiple passes result in a long rolling process, several times (more than 5 times) longer than normal rolling time, leading to very low efficiency. The long rolling time, the high temperature of the sheet metal exposed to air, and the significant influence of seasonal temperature variations make it impossible to guarantee that each rolling operation will be conducted in the same environment, resulting in large differences in performance between batches. Shutting down the mill to allow the sheet metal to cool down, and the fact that only one ingot can be cast at a time on the mill's roller table, greatly reduces production efficiency, and real-time monitoring of the sheet metal temperature is difficult to achieve. Therefore, it is clear that large deformation, few passes, and small deformation, multi-pass rolling processes cannot simultaneously solve the problems of coarse grains and uneven microstructure in sheet metal.

[0004] Changing the alloy composition is also a way to solve the problems of coarse grains and uneven microstructure in sheet metal. Adding grain-refining elements such as Mn and Ti to the alloy can increase the recrystallization temperature of Al-Cu-Mg high-strength aluminum alloys, inhibit recrystallization during solution treatment of heavily deformed rolled sheets, avoid abnormal grain growth, and result in a fine-grained microstructure. These elements are primarily found in Al... 20 The Cu2Mn3 form exists, and this dispersed phase can pin grain boundaries, hindering grain boundary movement. Since the grain boundaries cannot move, they cannot aggregate and grow, resulting in fine grains. However, higher Mn content tends to lead to Al... 20 The Cu2Mn3 dispersed phase is larger and more unevenly distributed. In addition, a large amount of Al2CuMg is heterogeneously nucleated in the dispersed phase, reducing the amount of Cu and Mg that can be used for solid solution strengthening in the sheet, thus reducing the strength of the sheet. The Al2CuMg phase attached to the dispersed phase heterogeneously nucleates, causing local stress concentration and severely reducing the fracture toughness of the alloy. At the same time, the effective content of Cu and Mg used for strengthening the alloy is reduced due to the attachment of the Al2CuMg phase to the dispersed phase heterogeneously nucleates, reducing the content of quenched supersaturated solid solution and thus reducing the strength of the sheet. This is also the main reason for the quenching sensitivity.

[0005] It is evident that providing a high-strength aluminum alloy thick plate that meets the requirements for flaw detection is of great significance to industrial production. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a rolling process for eliminating noise during flaw detection of high-strength aluminum alloy plates with low alloy content. The process involves sequentially performing melting, casting, homogenization treatment, sawing and milling, rolling, solution heat treatment, stretching, and artificial aging. By controlling the initial rolling temperature, rolling rate, rolling reduction, and final rolling temperature, the resulting high-strength aluminum alloy thick plate exhibits uniform microstructure along its thickness direction, small grain size, and passes non-destructive testing. It also possesses high strength and plasticity, as well as high fracture toughness. Furthermore, the aluminum alloy rolling process exhibits low deformation resistance, meeting the requirements for continuous process improvement and energy conservation in industrial production.

[0007] The technical solution of the present invention is as follows:

[0008] A rolling process for eliminating noise during flaw detection of high-strength aluminum alloy plates with low alloy content includes the following sequential processes: melting, casting, homogenization treatment, sawing and milling, rolling, solution heat treatment, stretching treatment, and artificial aging.

[0009] The homogenization heat treatment is carried out using a three-stage homogenization process: heating to 400-405℃ at a heating rate of 40℃ / h and holding for 3 hours; then heating to 445-460℃ at a heating rate of 40℃ / h and holding for 10-24 hours; and then heating to 492-496℃ at a heating rate of 10℃ / h and holding for 8-24 hours.

[0010] The main purpose of homogenization treatment is to reduce the non-uniformity of chemical composition and eliminate the internal stress of the ingot; to dissolve the non-equilibrium phase formed by rapid cooling of the ingot during the casting process, and then to slowly cool and precipitate the compound, so that the compound size becomes smaller and more uniform, thereby achieving the purpose of adjusting the compound.

[0011] After homogenization, the ingot needs to be cooled and then sawn. The purpose of sawing is that the head and tail of the ingot are in an unstable stage during casting, and the structure is prone to unevenness. Therefore, sawing removes the unqualified parts. Milling removes the anti-segregation layer on the surface of the ingot to obtain a good surface and ensure product quality.

[0012] Preheating before rolling involves placing the ingot at a higher temperature. The higher the temperature, the more vigorous the molecular activity. Macroscopically, this results in lower rolling resistance, which helps prevent cracking and facilitates rolling. Rolling at higher temperatures also reduces rolling resistance and saves energy.

[0013] Rolling involves heating the homogenized ingot and rolling it at 420°C after it is taken out of the furnace.

[0014] The rolling process employs 9-15 passes. The first three passes are rapid rolling, which rapidly increases the plate's energy storage, making the plate's recovery rate greater than the dislocation increase rate, thus reducing the plate's resistance to deformation. The middle passes are rapid rolling with large deformation, increasing the plate's energy while maintaining a dynamic recovery state. Subsequent rolling passes continuously reduce the rolling deformation resistance. The last three passes are rapid rolling with large reduction, with a single pass reduction rate greater than 17%, ensuring the final rolling temperature of the plate, which is not lower than 410℃. The remaining passes are slow rolling with small reduction. Dynamic recrystallization and dynamic recovery are the main mechanisms for weakening the deformation resistance during hot rolling of the plate. This mechanism requires higher energy storage to activate and can be maintained for a relatively long time once activated. When continuous slow rolling occurs, the plate temperature decreases, energy storage decreases, and deformation resistance gradually increases. Therefore, rapid rolling with large deformation is used in the middle passes.

[0015] In this invention, unless otherwise specified, a single-pass deformation of <5% is considered small deformation, a single-pass deformation of 5-10% is considered relatively small deformation, a single-pass deformation of 10.01-15% is considered relatively large deformation, and a single-pass deformation of >15.0% is considered large deformation.

[0016] In this alloy, an Mn content exceeding 0.50% will refine the Al grains. 20 The Cu2Mn3 phase aggregates and grows, making the alloy sensitive to quenching. Only by increasing the weight percentages of Cu and Mg to 4.5% and 1.8% or higher, respectively, can the alloy performance requirements be met. Therefore, in the industry, high-strength aluminum alloys with Mn < 0.50%, Cu < 4.50%, and Mg < 1.80% are classified as low-alloy-content high-strength alloys, while the rest are classified as high-alloy-content alloys.

[0017] The rolling process of this invention does not require machine shutdown for warming and involves fewer rolling passes. The first three passes, while ensuring proper bite, employ a large reduction and rapid rolling speed to guarantee high deformation energy storage in the sheet, allowing for sufficient recovery and recrystallization, thus reducing rolling stress. The middle passes use a small reduction and slow rolling speed to allow sufficient time for recovery and recrystallization. The odd-numbered middle passes use a large reduction and rapid rolling speed to increase internal energy storage in the sheet, ensuring a higher rolling temperature. This higher rolling temperature and deformation energy storage lower the critical stress for deformation, ensuring the sheet remains in a safe deformation state. The last three passes use a large reduction and low rolling speed to ensure a final rolling temperature of no less than 410°C, reducing internal energy storage and inhibiting recrystallization during subsequent solution treatment, effectively preventing abnormal grain growth.

[0018] Preferably, semi-continuous casting is used to obtain a low-alloy-content, high-strength aluminum alloy flat ingot, which comprises the following elements by weight percentage:

[0019] Si 0-0.70%, Fe 0-0.80%, Cu 3.5-5.0%, Mn 0.20-0.56%, Mg 1.2-1.8%, Cr 0-0.50%, Zn 0-0.55%, Ti 0-0.15%, with the balance being Al and unavoidable impurities.

[0020] Preferably, the flat ingot comprises the following elements by weight percentage:

[0021] Si 0.10-0.60%, Fe 0.12-0.80%, Cu 3.9-4.5%, Mn 0.30-0.45%, Mg 1.3-1.8%, Cr 0-0.10%, Zn 0.15-0.45%, Ti 0.01-0.15%, with the balance being Al and unavoidable impurities.

[0022] Preferably, solution heat treatment is performed on the rolled sheet at a solution temperature of 495℃ and a holding time of 2h.

[0023] Preferably, the pre-stretching treatment is performed after the solution heat-treated plate has been left to stand for 1-3 hours, and the pre-stretching deformation is 1.5-3.0%.

[0024] Preferably, artificial aging is performed, with the artificial aging process involving heat treatment at 191℃ for 10-18 hours to achieve the finished product state.

[0025] Preferably, high-strength aluminum alloy sheets after artificial aging are subjected to ultrasonic non-destructive testing; sheets that pass the non-destructive testing are then tested for tensile properties and fracture toughness, and those that pass the performance tests are packaged and put into storage.

[0026] In this invention, Al undergoes three-stage homogenization treatment 20 The Cu2Mn3 dispersed phase has a small size and relatively uniform distribution, exhibiting strong recrystallization inhibition ability. During rolling, by coordinating rolling temperature, rolling reduction, and rolling speed to ensure the final rolling temperature, a uniform microstructure and small grain size in the plate are obtained. During aging, the dispersed phase has a small size and relatively uniform distribution, and Al... 20 Cu2Mn3 effectively prevents the main strengthening phase from heterogeneously nucleating and growing at its edges, and avoids stress concentration around the dispersed phase, thus effectively improving the fracture toughness and plasticity of the plate. During quenching, it avoids the heterogeneous nucleation of the Al2CuMg phase attached to the dispersed phase, ensuring the effective content of Cu and Mg used to strengthen the alloy, increasing the content of supersaturated solid solution during quenching, and ensuring the formation of precipitated strengthening phases during aging, thereby improving the strength of the plate. The rolling process provided by this invention has a high effective strengthening component for forming precipitated strengthening phases, and the aging precipitates are uniform and fine, ensuring that the plate has both high strength and elongation.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. In the rolling process of this invention, rolling begins at 420°C. By coordinating and controlling the rolling deformation, rolling speed, and rolling passes, a stable final rolling temperature is obtained. The plate can recover sufficiently during the rolling process, reducing the plate's energy storage. A thick plate without flaw detection defects is obtained by using a low-alloy high-strength aluminum alloy.

[0029] 2. In the rolling process of this invention, a large reduction and rapid rolling are used in the odd-numbered intermediate passes, which can ensure that the material is in a low deformation resistance state in the subsequent low-speed rolling process, resulting in lower rolling force and reduced energy consumption. The larger deformation in the last three passes improves the penetration of the rolling force, forces the core of the plate to deform, reduces the difference in microstructure between the edge and thickness of the plate, and ensures uniform microstructure. This process can ensure that the plate has low deformation resistance, low rolling force, and low energy consumption during the rolling deformation process.

[0030] 3. In the low-alloy-content high-strength aluminum alloy obtained by the present invention, the number of dispersed phases is small and the distribution is uniform, which can effectively reduce the heterogeneous nucleation of Al2CuMg at the dispersed phase interface, avoid stress concentration at the sharp boundary of Al2CuMg, and improve the fracture toughness and plasticity of the alloy.

[0031] 4. In the rolling process provided by the present invention, the effective reinforcing component used to form the precipitated reinforcing phase is relatively high, ensuring that the plate has both high strength and elongation.

[0032] 5. By controlling the distribution of initial rolling temperature, rolling rate, rolling reduction rate, and final rolling temperature, this invention obtains thick plates with uniform microstructure and fine grains along the thickness direction, and relatively uniform grains between different thicknesses of the plates, with no defects detected. In addition, this rolling process has high production efficiency, compact production rhythm, stable production, and stable product performance. The production process does not require stopping the machine to wait for the ingot to cool down, the plate rolling process maintains a high temperature, the rolling resistance is small, and the energy consumption is low.

[0033] 6. The addition of alloying elements requires the use of high-purity master alloys, which are more expensive than pure aluminum and are an important part of the cost of plate casting. Therefore, the low-alloy high-strength aluminum alloy provided by this invention has a lower content of Cu, Mg and Mn, which saves costs, reduces casting difficulty, and enhances product competitiveness. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a microstructure diagram of Example 1.

[0036] Figure 2 This is a non-destructive testing image from Example 1.

[0037] Figure 3 This is a microscopic tissue diagram of Comparative Example 1.

[0038] Figure 4 This is the non-destructive testing image for Comparative Example 1.

[0039] Figure 5 This is the non-destructive testing image for Comparative Example 2. Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0041] Example 1

[0042] A rolling process for eliminating noise during flaw detection of low-alloy high-strength aluminum alloy sheets, comprising the following steps:

[0043] (1) Semi-continuous casting ingot:

[0044] Semi-continuous casting was used to obtain a low-alloy, high-strength aluminum alloy flat ingot, which comprises the following elements by weight percentage:

[0045] Si 0.32%, Fe 0.28%, Cu 4.05%, Mn 0.42%, Mg 1.40%, Cr 0.01%, Zn 0.14%, Ti 0.02%, balance Al and unavoidable impurities;

[0046] (2) Homogenization treatment:

[0047] A three-stage homogenization heat treatment process was adopted: heating to 400℃ at a heating rate of 40℃ / h and holding for 3h; then heating to 452℃ at a heating rate of 40℃ / h and holding for 12h; then heating to 495℃ at a heating rate of 10℃ / h and holding for 18h; to eliminate residual stress and reduce chemical composition inhomogeneity; sawing and milling were then performed.

[0048] After homogenization, the ingot needs to be cooled and then sawn. The purpose of sawing is that the head and tail of the ingot are in an unstable stage during casting, and the structure is prone to unevenness. Therefore, sawing removes the unqualified parts. Milling removes the anti-segregation layer on the surface of the ingot to obtain a good surface and ensure product quality.

[0049] (3) Rolling:

[0050] Rolling involves heating the homogenized ingot and rolling it at 420°C after it is taken out of the furnace.

[0051] The rolling process uses 13 passes, with the first three passes being rapid rolling at a speed of 1.0 m / s. The reduction in the first three passes accounts for 23% of the total deformation.

[0052] The last three passes have a large reduction, with a single pass reduction rate of more than 17%, and the rolling speed is 1.0 m / s;

[0053] The middle pass (i.e., the 7th pass) has a reduction of 10% of the total deformation and a rolling speed of 1.0 m / s.

[0054] For the remaining passes, the rolling speed is 0.75 m / s;

[0055] The first three passes employ a large reduction and rapid rolling speed to ensure a high deformation energy storage in the sheet, allowing for sufficient recovery and recrystallization, and reducing rolling stress. The middle passes use a small reduction and slow rolling speed to allow sufficient time for recovery and recrystallization. The middle odd-numbered passes use a large reduction and rapid rolling speed to increase the internal energy storage in the sheet, ensuring a higher rolling temperature. This higher rolling temperature and deformation energy storage lower the critical stress for deformation, ensuring the sheet is in a safe deformation state. The last three passes use a large reduction and low rolling speed to ensure a final rolling temperature of no less than 410℃, reducing the internal energy storage in the sheet, inhibiting recrystallization during subsequent solution treatment, and effectively preventing abnormal grain growth.

[0056] (4) Solution heat treatment:

[0057] The rolled sheet was subjected to solution heat treatment at a temperature of 495℃ for 2 hours.

[0058] (5) Pre-stretching treatment:

[0059] After the solution heat-treated sheet is left to stand for 1-3 hours, the pre-stretch deformation is 1.5-3.0%.

[0060] (6) Artificial aging:

[0061] The artificial aging process involves heat treatment at 191℃ for 12 hours to achieve the finished product state.

[0062] (7) Inspect the packaging:

[0063] Ultrasonic non-destructive testing was performed on the high-strength aluminum alloy sheets after artificial aging, and the results are shown in Table 1. The tensile properties and fracture toughness of the sheets that passed the non-destructive testing were tested, and the results are shown in Table 2. The sheets that passed the performance testing were packaged and put into storage. The microstructure of the products is shown in [Table 1]. Figure 1 Non-destructive testing images are shown. Figure 2 .

[0064] In the rolling process of this invention, the dispersed phase Al 20 The small size and relatively uniform distribution of Cu2Mn3 prevent the Al2CuMg phase from attaching to the nucleation sites of the dispersed phase, ensuring high fracture toughness of the plate. Simultaneously, the number of Al2CuMg nuclei attached to the dispersed phase is significantly reduced, minimizing stress concentration. The effective reinforcing components used to form the precipitated strengthening phase are high, ensuring that the plate possesses both high strength and elongation.

[0065] Comparative Example 1

[0066] A rolling process for eliminating noise during flaw detection of low-alloy high-strength aluminum alloy sheets, comprising the following steps:

[0067] (1) Semi-continuous casting ingot:

[0068] Semi-continuous casting was used to obtain a low-alloy, high-strength aluminum alloy flat ingot, which comprises the following elements by weight percentage:

[0069] Si 0.09%, Fe 0.06%, Cu 4.61%, Mn 0.72%, Mg 1.62%, Cr 0.01%, Zn 0.12%, Ti 0.04%, balance Al and unavoidable impurities;

[0070] (2) Homogenization treatment:

[0071] Heating rate of 10℃ / h to 495℃, holding for 24h; eliminating residual stress and reducing uneven chemical composition; sawing and milling.

[0072] (3) Rolling:

[0073] Rolling involves heating the homogenized ingot to 400℃ and rolling it. The rolling process consists of 13 passes. The first three passes use a small reduction and low rolling speed (0.75 m / s), with a single-pass deformation of <5%. In the middle passes, the reduction gradually increases, with a single-pass deformation of 17% and a rolling speed of 1.0 m / s. The last two passes use a small reduction, with a rolling deformation of <5%, and a high rolling speed of 2.5 m / s. The final rolling temperature is 380℃.

[0074] (4) Solution heat treatment:

[0075] The rolled sheet was subjected to solution heat treatment at a temperature of 495℃ for 2 hours.

[0076] (5) Pre-stretching treatment:

[0077] After the solution heat-treated sheet is left to stand for 1-3 hours, the pre-stretch deformation is 1.5-3.0%.

[0078] (6) Artificial aging:

[0079] The artificial aging process involves heat treatment at 191℃ for 12 hours to achieve the finished product state.

[0080] (7) Inspect the packaging:

[0081] Ultrasonic non-destructive testing was performed on the high-strength aluminum alloy sheets after artificial aging, and the results are shown in Table 1. The tensile properties and fracture toughness of the sheets that passed the non-destructive testing were tested, and the results are shown in Table 2. The sheets that passed the performance testing were packaged and put into storage. The product microstructure diagram is shown below. Figure 3 Non-destructive testing images are shown. Figure 4 .

[0082] Comparative Example 2

[0083] A rolling process for eliminating noise during flaw detection of low-alloy high-strength aluminum alloy sheets, comprising the following steps:

[0084] (1) Semi-continuous casting ingot:

[0085] Semi-continuous casting was used to obtain a low-alloy, high-strength aluminum alloy flat ingot, which comprises the following elements by weight percentage:

[0086] Si 0.08%, Fe 0.05%, Cu 4.54%, Mn 0.45%, Mg 1.69%, Cr 0.01%, Zn 0.13%, Ti 0.02%, balance Al and unavoidable impurities;

[0087] (2) Homogenization treatment:

[0088] Heating rate of 10℃ / h to 495℃, holding for 24h; eliminating residual stress and reducing uneven chemical composition; sawing and milling.

[0089] (3) Rolling:

[0090] Rolling involves heating the homogenized ingot to 400℃ and rolling it. The rolling process consists of 13 passes. The first three passes use a small reduction and low rolling speed, with a single-pass deformation of <5% and a rolling speed of 0.5m / s. In the middle passes, the reduction gradually increases, with a single-pass deformation of 17% and a rolling speed of 1.0m / s. The last two passes use a small reduction, with a rolling deformation of <5% and a high rolling speed of 2.5m / s. The final rolling temperature is 380℃.

[0091] (4) Solution heat treatment:

[0092] The rolled sheet was subjected to solution heat treatment at a temperature of 495℃ for 2 hours.

[0093] (5) Pre-stretching treatment:

[0094] After being cooled by water after being removed from the furnace and quenched, the pre-stretch deformation of the plate after being left for 1-3 hours is 1.5-3.0%.

[0095] (6) Artificial aging:

[0096] The artificial aging process involves heat treatment at 191℃ for 12 hours to achieve the finished product state.

[0097] (7) Inspect the packaging:

[0098] Ultrasonic non-destructive testing was performed on high-strength aluminum alloy sheets after artificial aging (see Table 1). Tensile properties and fracture toughness were tested on the sheets that passed the non-destructive testing (see Table 2). Qualified sheets were packaged and stored. Non-destructive testing images are available in […]. Figure 5 .

[0099] Test results:

[0100] The microstructures of Comparative Example 1 and Example 1 are as follows: Figure 1 and Figure 2 As shown, in Comparative Example 1, the alloy composition is higher, the number of dispersed phases in the microstructure is greater and the distribution is uneven, and some dispersed phases are surrounded by long strips of Al2CuMg. In Example 1, the alloy elements are lower, especially the Mn content is lower, the number of dispersed phases in the alloy is less and the distribution is relatively uniform, and no Al2CuMg was found around the dispersed phases as heterogeneous nucleation cores, which effectively ensures that Cu and Mg alloy elements do not precipitate prematurely during the solid solution process, and the effective strengthening components used to form precipitated strengthening phases are higher. Under the condition of lower Cu and Mg content, the plate is guaranteed to have both high strength and elongation.

[0101] The ultrasonic non-destructive testing images of Comparative Example 1, Comparative Example 2, and Example 1 are shown below. Figure 4 , Figure 5 and Figure 2 As shown, Comparative Example 1 shows scattered noise areas at the edges of the board, with a maximum noise amplitude of 25%, which meets the Class A flaw detection standard. Comparative Example 2 shows dense flaw detection noise throughout the entire board, with a maximum noise amplitude of 90.2%, which does not meet the Class A flaw detection standard. Example 1's ultrasonic non-destructive testing results show no defects, no noise areas, and the entire board passes the flaw detection test.

[0102] Table 1. Results of Non-destructive Testing of Plates

[0103] Non-destructive testing results Comparative Example 1 Noise is present in some areas, but meets Class A standards. Comparative Example 2 Noise, not up to standard Example No noise, qualified

[0104] The fracture toughness of Comparative Example 1, Comparative Example 2, and Example 1 is shown in Table 2. The fracture toughness of the plates produced by the three rolling processes all meet the requirements of the AMS4101 standard. Comparative Example 1 has the lowest fracture toughness, Comparative Example 2 shows a significant improvement in fracture toughness, and Example 1 has the highest fracture toughness. Example 1 is a low-composition high-strength aluminum alloy. The rolling process of this invention can ensure that the microstructure of the thick plate has small differences along the thickness. At the same time, the dispersed phase in the microstructure of the thick plate is uniform and there is no obvious Al2CuMg formed by the attached dispersed phase as a heterogeneous nucleation core. This characteristic microstructure can effectively avoid stress concentration and better ensure that the plate has good fracture toughness.

[0105] Table 2 Fracture toughness of plates

[0106]

[0107] The mechanical properties of Comparative Example 1, Comparative Example 2, and Example 1 are shown in Table 3. The low-alloy-content high-strength aluminum alloy of Example 1 has both high strength and elongation. The low-alloy-content high-strength aluminum alloy has fewer dispersed phases and a uniform distribution, which can effectively reduce the heterogeneous nucleation of Al2CuMg at the dispersed phase interface, avoid stress concentration at sharp Al2CuMg boundaries, and improve the fracture toughness and plasticity of the alloy. The rolling process of the present invention has a high effective strengthening component for forming precipitated strengthening phases, ensuring that the plate has both high strength and elongation.

[0108] Table 3 Mechanical properties of sheet metal

[0109]

[0110]

[0111] Although the present invention has been described in detail with reference to preferred embodiments, it is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A rolling process for eliminating noise during flaw detection of low-alloy high-strength aluminum alloy sheets, characterized in that, This includes the sequential processes of smelting, casting, homogenization, sawing and milling, rolling, solution heat treatment, pre-stretching, and artificial aging. The homogenization heat treatment is carried out using a three-stage homogenization process: heating to 400-405℃ at a heating rate of 40℃ / h and holding for 3 hours; then heating to 445-460℃ at a heating rate of 40℃ / h and holding for 10-24 hours; and then heating to 492-496℃ at a heating rate of 10℃ / h and holding for 8-24 hours. Semi-continuous casting was used to obtain low-alloy high-strength aluminum alloy flat ingots. The flat ingots contained the following elements by weight percentage: Si 0.10-0.60%, Fe 0.12-0.80%, Cu 3.9-4.5%, Mn 0.30-0.45%, Mg 1.3-1.8%, Cr 0-0.10%, Zn 0.15-0.45%, Ti 0.01-0.15%, with the balance being Al and unavoidable impurities. Rolling: Heating the homogenized flat ingots and rolling them at 420°C after they are taken out of the furnace; The rolling process uses 9-15 passes, with the first three passes being fast rolling; the middle passes being fast rolling with large deformation; and the last three passes being fast rolling with large reduction. The reduction rate of a single pass is greater than 17%, and the remaining passes are slow rolling with small reduction. The final rolling temperature of the plate is not lower than 410℃. Solution heat treatment: The rolled sheet is subjected to solution heat treatment at a temperature of 495℃ and a holding time of 2 hours. Pre-stretching treatment: After the solution heat-treated sheet has been left to stand for 1-3 hours, pre-stretching treatment is performed, with a pre-stretch deformation of 1.5-3.0%. Artificial aging, the artificial aging regime is 191℃, heat treatment for 10-18 hours.

2. The rolling process for eliminating noise during flaw detection of low-alloy high-strength aluminum alloy plates as described in claim 1, characterized in that, Semi-continuous casting was used to obtain a low-alloy, high-strength aluminum alloy flat ingot, which comprises the following elements by weight percentage: Si 0-0.70%, Fe 0-0.80%, Cu 3.5-5.0%, Mn 0.20-0.56%, Mg 1.2-1.8%, Cr 0-0.50%, Zn 0-0.55%, Ti 0-0.15%, with the balance being Al and unavoidable impurities.

3. The rolling process for eliminating noise during flaw detection of low-alloy high-strength aluminum alloy plates as described in claim 1, characterized in that, Ultrasonic non-destructive testing is performed on high-strength aluminum alloy sheets after artificial aging; tensile properties and fracture toughness are tested on sheets that pass the non-destructive testing, and those that pass the performance test are packaged and put into storage.

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