Processing method and application of high-cu-content al-cu alloy plate

Abstract

The application discloses a processing method and application of high Cu content Al-Cu alloy plate material, and the method comprises the following steps: S1, quenching after first solid solution treatment of high Cu content Al-Cu alloy plate material; S2, cold deformation of the quenched high Cu content Al-Cu alloy plate material; S3, cooling, heat preservation treatment and deformation of the high Cu content Al-Cu alloy plate material after heating and overaging treatment of the cold deformed high Cu content Al-Cu alloy plate material; S4, quenching and aging treatment of the deformed high Cu content Al-Cu alloy plate material after second solid solution treatment. The alloy forming method improves the impact resistance of the prepared aluminum alloy material. The method can refine and spheroidize the coarse and brittle second phase in the high Cu content Al-Cu alloy plate material, and can obtain fine equiaxed grains, so as to improve the strength and plasticity and toughness of the alloy and improve the impact resistance.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, specifically to a processing method and application of high Cu content Al-Cu alloy plates. Background Technology

[0002] Al-Cu alloys are typical age-hardening alloys, and in practice, the heat treatment state used is mostly T87. They are commonly used as structural materials for high-speed transport equipment such as aircraft, rockets, and armored vehicles. Therefore, improving their strength and impact resistance is crucial. The strength of Al-Cu alloys increases with increasing Cu content. The maximum solid solubility of Cu in the aluminum matrix is ​​5.65 wt%. Undissolved Cu often exists as coarse, hard, and brittle second phases, such as Al2Cu and Al7Cu2Fe. These phases can induce stress concentration and damage during plastic deformation, impairing the alloy's ductility, toughness, and impact resistance. Reducing the size of these second phases and making them spherical and more uniformly distributed is an effective way to improve the alloy's ductility, toughness, and impact resistance.

[0003] On the other hand, grain refinement can simultaneously improve the strength and plasticity of alloys, making it an effective way to enhance the impact resistance of materials. During the smelting stage, grain refiners are typically added to the melt to refine the ingot grains. In the forming stage, there are two main methods for grain refinement: severe plastic deformation (SPD) and deformation heat treatment. SPD has a very strong grain-refining effect on polycrystalline materials, yielding submicron or even nanoscale grains. SPD methods mainly include equal channel angle extrusion, high-pressure torsion, and cumulative roll-welding, but currently these methods can only produce small-sized materials, with widths or diameters not exceeding 500 mm, and require sophisticated equipment, limiting their practical application. In contrast, deformation heat treatment has lower equipment requirements, can produce large-size plates, and has more applications in actual industrial production.

[0004] Currently used traditional deformation heat treatment methods for grain refinement involve solution treatment, which allows solute atoms to dissolve into the matrix, resulting in a supersaturated solid solution. During subsequent over-aging, the unstable supersaturated solid solution precipitates and grows, yielding high-density (sub)micron-sized second-phase particles. Subsequent warm rolling generates numerous dislocations around these particles, resulting in high deformation energy storage. During high-temperature, short-time recrystallization solution treatment, these sites can stimulate recrystallization grain nucleation, increasing the recrystallization nucleation rate and refining the grains. This method of using precipitated phases to increase the recrystallization nucleation rate is called Particle Stimulated Nucleation (PSN). To achieve good grain refinement, warm rolling deformation is often required to be above 80%, but large deformation can easily lead to microcracks or even direct cracking in the sheet material. To prevent cracking, repeated heating is required during warm rolling to reduce the deformation resistance of the sheet and restore its plasticity. Furthermore, because the sheet length increases during warm rolling, it must be cut before further heating, which increases energy consumption and production time. To address the problems of sheet cracking and long production times caused by repeated heating, a continuous rolling process during warm rolling has been developed. This process involves increasing the initial temperature of the warm roll to avoid repeated heating during the rolling process. However, for Al-Cu alloys with high Cu content, the presence of a large number of coarse, hard, and brittle second phases increases the risk of cracking during rolling. Increasing the warm rolling temperature reduces deformation energy storage, failing to fully utilize the PSN effect and limiting the grain refinement effect. Simultaneously, increasing the rolling temperature promotes the growth of the second phase, which is difficult to dissolve into the matrix during subsequent short-term recrystallization and solidification. Therefore, it is impossible to redefine uniform, fine, and dispersed precipitates during the final aging process, thus hindering further improvement in the alloy's strength and impact resistance.

[0005] Therefore, there is a need to develop an efficient method for refining grains and the second phase in Al-Cu alloy plates with high Cu content. Summary of the Invention

[0006] This invention aims to solve the aforementioned technical problems existing in the prior art. To this end, this invention proposes a processing method for high-Cu content Al-Cu alloy sheets, which can refine and spheroidize the coarse, hard, and brittle second phase in the high-Cu content Al-Cu alloy sheets, thereby improving ductility and toughness; simultaneously, it refines the grain structure of the sheet, improving the strength and plasticity of the alloy. The combined effect of the optimized precipitates and grain structure significantly improves the impact resistance of high-Cu content Al-Cu alloy sheets in the T87 temper.

[0007] This invention also proposes the application of a processing method for high Cu content Al-Cu alloy plates in the preparation of aerospace components or armor components.

[0008] According to one aspect of the present invention, a method for processing high Cu content Al-Cu alloy plates is provided, comprising the following steps:

[0009] S1. The high-Cu content Al-Cu alloy plate is subjected to a first solution treatment followed by quenching;

[0010] S2. Cold deformation of the quenched high-Cu content Al-Cu alloy sheet;

[0011] S3. After cold deformation, the high Cu content Al-Cu alloy sheet is subjected to aging treatment, followed by cooling, heat preservation treatment, and deformation.

[0012] S4. The deformed high-Cu content Al-Cu alloy plate is subjected to a second solution treatment, followed by quenching and aging treatment.

[0013] The high Cu content Al-Cu alloy plate contains 5.5 wt.% ≤ Cu ≤ 7.0 wt.%.

[0014] According to the embodiments of the first aspect of the present invention, at least the following beneficial effects are achieved:

[0015] This invention, based on traditional deformation heat treatment, adds a cold deformation step before the over-aging treatment in step S3. This step pre-breaks up the coarse, insoluble primary second phase in the sheet metal, reducing stress concentration during subsequent deformation and making the sheet less prone to cracking. Simultaneously, it introduces a certain amount of dislocations, increasing the number of second phase nuclei and the driving force for growth during over-aging, promoting the recrystallization of more second phases in the matrix. This significantly increases the recrystallization grain nucleation rate during subsequent solid solution treatment, thereby refining the grains. The coarse second phase is broken up after deformation in step S3, reducing its size. During high-temperature solid solution treatment, it can dissolve and spheroidize, increasing the supersaturation of the solid solution. The re-aging treatment in step S4 precipitates a uniformly dispersed nanoscale reinforcing phase in the matrix, which, together with grain refinement, improves the impact resistance of the alloy.

[0016] This method has strong dimensional applicability and can be applied to large-size boards, and the boards are not prone to cracking during processing; the process is simple, the equipment requirements are low, and it is easy to realize industrial production.

[0017] In some embodiments of the present invention, the composition of the high Cu content Al-Cu alloy sheet is as follows: 6.1 wt.% ≤ Cu ≤ 6.6 wt.%, trace element content ≤ 0.5 wt.%, impurity element Fe ≤ 0.2 wt.%, Si ≤ 0.15 wt.%, with the balance being Al and unavoidable impurities. Cu is the main additive element; the higher its content, the higher the alloy strength. However, excessive Cu content is detrimental to the alloy's ductility and toughness. Trace elements dissolved in the alloy matrix can also provide a certain degree of solid solution strengthening. Impurity elements can harm the alloy's properties, and their content should be minimized.

[0018] In some embodiments of the present invention, the trace elements include Mn, Mg, Ti and Zr.

[0019] In some embodiments of the present invention, in step S1, the temperature of the first solution treatment is 500–540°C.

[0020] The solution temperature within the above temperature range can ensure rapid dissolution of most of the primary phase, while softening the metal and reducing the resistance to subsequent cold deformation.

[0021] In some embodiments of the present invention, in step S1, the temperature of the first solution treatment is 520–535°C.

[0022] In some embodiments of the present invention, in step S1, the time for the first solution treatment is 1 to 5 hours.

[0023] In some embodiments of the present invention, in step S1, the time for the first solution treatment is 1 to 3 hours.

[0024] In some embodiments of the present invention, in step S2, the cold deformation includes cold rolling deformation, and the deformation amount of the cold deformation is 10% to 50%.

[0025] The deformation within the above range helps to control the microstructure of the alloy and prevent the alloy from cracking during deformation.

[0026] In some embodiments of the present invention, in step S2, the cold deformation includes cold rolling deformation, and the deformation amount of the cold deformation is 15% to 45%.

[0027] In some embodiments of the present invention, step S2 includes multiple cold rolling deformations.

[0028] In some embodiments of the present invention, in step S3, the over-aging temperature is 350–450°C.

[0029] Over-aging temperatures within the above range can promote the formation of more (sub)micron-sized second phases, fully leveraging the PSN effect.

[0030] In some embodiments of the present invention, in step S3, the over-aging temperature is 400–425°C.

[0031] In some embodiments of the present invention, in step S3, the over-aging heat preservation time is 6 to 30 hours.

[0032] In some embodiments of the present invention, in step S3, the over-aging heat preservation time is 12 to 24 hours.

[0033] In some embodiments of the present invention, in step S3, the temperature after cooling is 200-300°C.

[0034] In some embodiments of the present invention, in step S3, the temperature of the heat preservation treatment is 200-300°C.

[0035] In some embodiments of the present invention, in step S3, the deformation amount is 40% to 90%.

[0036] In some embodiments of the present invention, in step S3, the deformation amount is 50% to 80%.

[0037] In some embodiments of the present invention, in step S3, the deformation includes warm rolling deformation.

[0038] In some embodiments of the present invention, step S3 includes multiple passes of warm rolling deformation.

[0039] In some embodiments of the present invention, in step S3, the temperature of the warm rolling deformation is 200-300°C.

[0040] After the over-aging heat treatment is completed, the material is directly cooled to the warm rolling temperature (the deformation temperature in step S3), without the need to cool to room temperature and reheat to the warm rolling temperature. During the warm rolling process, continuous rolling is carried out without repeated heating and without cutting the plate, which can reduce energy consumption and production time. The warm rolling temperature is suitable, which can ensure that the rolling can be carried out continuously, prevent the second phase from growing, and retain a high amount of deformation energy in the alloy.

[0041] In some embodiments of the present invention, the cold deformation amount in step S2 and the deformation amount in step S3 satisfy: 60% ≤ δc + δw - δc * δw ≤ 90%.

[0042] Where δc is the cold deformation amount, which is the initial thickness minus the final cold deformation thickness and the deformation amount relative to the initial thickness, and δw is the deformation amount, which is the final cold deformation thickness minus the final deformation thickness and the deformation amount relative to the final cold deformation thickness.

[0043] Under the aforementioned relationship of deformation amounts, by rationally allocating the deformation amounts, the risk of rolling cracks in high Cu content Al-Cu alloy plates can be avoided; at the same time, under the aforementioned relationship of deformation amounts, it is beneficial to break and spheroidize coarse, hard, and brittle second phases, thereby reducing stress concentration in the plates and improving the plasticity and toughness of high Cu content Al-Cu alloy plates.

[0044] In some embodiments of the present invention, in step S4, the temperature of the second solution treatment is 510–540°C.

[0045] Solution treatment within the above temperature range is beneficial for maximizing the dissolution and recrystallization of the alloy, and optimizing the alloy's microstructure and impact resistance.

[0046] In some embodiments of the present invention, in step S4, the temperature of the second solution treatment is 520–535°C.

[0047] In some embodiments of the present invention, the second solution treatment takes 10 min to 60 min.

[0048] In some embodiments of the present invention, the second solution treatment takes 10 min to 30 min.

[0049] In some embodiments of the present invention, in step S4, during the heating step, the heating rate of the high Cu content Al-Cu alloy plate is ≥1℃ / s.

[0050] In some embodiments of the present invention, in step S4, the re-aging treatment temperature is 160-170°C.

[0051] The re-aging temperature within the above range helps stabilize the grain structure of the alloy, prevent grain growth, maintain the fine grain state of the alloy, and at the same time fully precipitate the nanoscale strengthening phase, thereby improving the impact resistance of the alloy.

[0052] In some embodiments of the present invention, in step S4, the heat preservation time for re-aging is 10 to 24 hours.

[0053] In some embodiments of the present invention, in step S4, the time interval between the quenching step and the re-aging treatment step is no more than 1 hour.

[0054] The aforementioned time intervals help reduce the impact of natural aging and fully utilize the role of re-aging treatment.

[0055] According to a second aspect of the present invention, a processing method for high Cu content Al-Cu alloy plates is proposed for use in the preparation of aerospace components or armor components. Attached Figure Description

[0056] Figure 1 This is a flowchart illustrating an embodiment of the present invention;

[0057] Figure 2 The grain structure of the longitudinal section after treatment in Example 1;

[0058] Figure 3 Metallographic image of a longitudinal section of a high-Cu content Al-Cu alloy plate in T87 condition for industrial production;

[0059] Figure 4Scanning electron microscope (SEM) image of the second phase distribution in a T87 temper plate of high Cu content Al-Cu alloy for industrial production;

[0060] Figure 5 This is a scanning electron microscope image of the second phase distribution after processing in Example 1;

[0061] Figure 6 The grain structure of the longitudinal section after treatment in Example 2;

[0062] Figure 7 The images show the T87 state plate of high Cu content Al-Cu alloy produced industrially, and the stress-strain curves obtained by treating the plate and then subjecting it to high strain rate impact in Example 2.

[0063] Figure 8 This is a schematic diagram of the traditional deformation heat treatment process in Comparative Example 1;

[0064] Figure 9 This is a grain structure diagram obtained by conventional deformation heat treatment in Comparative Example 1;

[0065] Figure 10 This is a scanning electron microscope image of the second phase distribution after conventional deformation heat treatment and re-aging in Comparative Example 1. Detailed Implementation

[0066] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0067] Example 1

[0068] This embodiment provides a processing method for high Cu content Al-Cu alloy plates, comprising the following steps:

[0069] The high-Cu content Al-Cu alloy plate has an initial thickness of 20.0 mm, a width of 1800 mm, and a length of 2000 mm. Its chemical composition is Cu 6.4 wt.%, Mn 0.25 wt.%, Ti 0.03 wt.%, Fe ≤ 0.20 wt.%, Si ≤ 0.15 wt.%, with the remainder being Al and unavoidable impurities.

[0070] S1. Solution quenching treatment is carried out on Al-Cu alloy plates with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace at a temperature of 530℃. After reaching the temperature, the plates are placed in the furnace and the holding time is calculated after the temperature stabilizes. The holding time is 3 hours. After the holding time is completed, the plates are immediately removed from the furnace and water quenched.

[0071] S2. The water-quenched sheet is cold-rolled and deformed at room temperature. After one deformation pass, the sheet thickness is reduced to 17.0 mm.

[0072] S3. The cold-rolled and deformed sheet is subjected to over-aging treatment. The over-aging temperature is set to 400℃. After the furnace reaches the temperature, the sheet is placed in the furnace. After the temperature stabilizes, the holding time is calculated and the holding time is 24 hours. After the holding time is completed, the sheet is cooled to 300℃ and held at 300℃ for another 2 hours. After the holding time is completed, the sheet is taken out of the furnace and subjected to continuous warm rolling deformation. After 5 passes, the sheet is rolled into a thickness of 5.1mm.

[0073] S4. The sheet metal after five rolling passes is rapidly heated to 535℃ for high-temperature short-time recrystallization solution treatment. The recrystallization solution treatment is carried out in a salt bath furnace, and the holding time is 20 minutes. After the holding time, it is immediately quenched in water at room temperature. After about 20 minutes, the recrystallized solution alloy is subjected to re-aging treatment to reach the peak aging state. The aging temperature is 170℃ and the aging time is 10 hours.

[0074] Table 1 below shows the thickness and deformation of the sheet metal before and after each rolling pass in Example 1. The cold rolling deformation (δ) is... c The deformation is calculated by subtracting the final cold-rolled thickness from the initial thickness and then retrieving the deformation relative to the initial thickness; the deformation during warm rolling (δ) is... w The total deformation (δ) is the deformation amount relative to the final cold-rolled thickness, calculated by subtracting the final warm-rolled thickness from the final cold-rolled thickness. c +δ w -δ c *δ w The deformation is calculated by subtracting the final warm-rolled thickness from the initial thickness and then considering the deformation relative to the initial thickness. In Example 1, the total deformation was 74.5%.

[0075] Table 1. Thickness and deformation of the sheet metal before and after each rolling pass in Example 1

[0076]

[0077]

[0078] Figure 2 The grain structure of the longitudinal section of the plate in Example 1 after re-aging treatment is fine and uniformly distributed equiaxed crystals, and the average grain size measured by the truncation method is 18.2 μm.

[0079] Figure 3 Metallographic image of a longitudinal section of a high-Cu content Al-Cu alloy plate in T87 condition, produced industrially. The grains are uneven, coarse, and elongated, with an average grain size greater than 150 μm.

[0080] Figure 4Scanning electron microscope (SEM) images of the second phase distribution in a T87 state plate of high Cu content Al-Cu alloy produced in industrial applications. The second phase is coarse and unevenly distributed, with the largest second phase reaching 12.5 μm in size and the smallest being 0.29 μm.

[0081] Figure 5 The image shows a scanning electron microscope (SEM) image of the second phase distribution of the plate material in Example 1 after re-aging treatment. The second phase is relatively uniformly distributed, and the coarse second phase is fully broken up and spheroidized, with a maximum size of only 4.9 μm.

[0082] Example 2

[0083] This embodiment provides a processing method for high Cu content Al-Cu alloy plates, comprising the following steps:

[0084] The chemical composition of the high-Cu content Al-Cu alloy plate is Cu 6.6 wt.%, Mn 0.35 wt.%, Ti 0.05 wt.%, Fe ≤ 0.20 wt.%, Si ≤ 0.15 wt.%; the remainder is Al and unavoidable impurities.

[0085] S1. Solution quenching treatment is performed on Al-Cu alloy plates with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace at a temperature of 535℃. After reaching the temperature, the plates are placed in the furnace and the holding time is calculated after the temperature stabilizes. The holding time is 2 hours. After the holding time is completed, the plates are immediately removed from the furnace and water quenched.

[0086] S2. The solution-treated sheet is cold-rolled at room temperature. The initial thickness of the sheet is 20.0 mm. After two passes of cold rolling deformation, the thickness of the sheet is reduced to 14.0 mm.

[0087] S3. The cold-deformed sheet is subjected to an aging treatment, with the aging temperature set at 425℃. After the furnace reaches the desired temperature, the sheet is placed in the furnace and the holding time is calculated after the temperature stabilizes. The holding time is 12 hours. After the holding time is completed, the sheet is cooled to 300℃ and then held at 300℃ for another hour. After the holding time is completed, the sheet is removed from the furnace and subjected to continuous warm rolling deformation. After 5 passes, the sheet is rolled into a sheet with a thickness of 4.2mm. The sheet is not reheated during the warm rolling process.

[0088] Table 2 shows the thickness and deformation of the sheet metal before and after rolling in Example 2. The total deformation in Example 2 is 79.0%.

[0089] Table 2. Thickness and deformation of the sheet metal before and after each rolling pass in Example 2

[0090]

[0091] S4. After five passes of rolling, the plate is rapidly heated to 535°C for high-temperature short-time recrystallization solution treatment. The recrystallization solution treatment is carried out in a salt bath furnace and the holding time is 10 minutes. After the holding time is completed, the plate is immediately quenched in water at room temperature. The recrystallized solution alloy is then subjected to re-aging treatment to reach the peak aging state. The aging temperature is 170°C and the aging time is 12 hours.

[0092] Figure 6 The grain structure of the plate material in Example 2 after re-aging is fine and uniformly distributed equiaxed crystals. The average grain size measured by the cross-section method is 16.9 μm.

[0093] Figure 7 The high-Cu content Al-Cu alloy T87 temper sheet produced industrially, and the sheet from Example 2 after reaging, are shown in the high-speed impact stress-strain curves. The high-speed impact test was conducted in a split Hopkinson pressure bar apparatus at an impact pressure of 0.4 MPa. The sheet treated by this method showed improved strength and strain compared to the industrially produced T87 temper sheet. The yield strength, peak strength, and strain of the T87 temper sheet were 413 MPa, 615 MPa, and 0.254, respectively, while those of Example 2 were 487 MPa, 674 MPa, and 0.286, respectively, representing increases of 17.9% and 9.6% in yield strength and peak strength, respectively. Using the formula... Calculate the plastic absorption work for both, where W is the plastic absorption work, and σ and ε are the stress and strain, respectively. The W for industrially produced T87 temper sheet is 131.380 MJ / m. 3 The W of the plate in Example 2 is 154.952 MJ / m. 3 The value of W is 17.9% higher than that of T87 condition sheet. The increase in W indicates that the sheet can absorb more energy during impact, which is beneficial to improving impact resistance.

[0094] Combination Figures 2-7 It is known that the processing method in this invention can effectively improve the microstructure of high Cu content Al-Cu alloys produced in industrial production, transforming them from coarse and uneven elongated grains into fine and uniform equiaxed grains, with the average grain size reduced to below 20 μm; the coarse and unevenly distributed second phase is fully broken up and spheroidized, with a size of less than 4.9 μm, thereby improving the high strain rate impact performance of high Cu content Al-Cu alloys.

[0095] Example 3

[0096] This embodiment provides a processing method for high Cu content Al-Cu alloy plates, comprising the following steps:

[0097] The high-Cu content Al-Cu alloy plate has an initial thickness of 20.0 mm, a width of 1800 mm, and a length of 2000 mm. Its chemical composition is Cu 6.6 wt.%, Mn 0.35 wt.%, Ti 0.05 wt.%, Fe ≤ 0.20 wt.%, Si ≤ 0.15 wt.%, with the remainder being Al and unavoidable impurities.

[0098] S1. Solution quenching treatment is performed on Al-Cu alloy plates with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace at a temperature of 500℃. After reaching the temperature, the plates are placed in the furnace and the holding time is calculated after the temperature stabilizes. The holding time is 2 hours. After the holding time is completed, the plates are immediately removed from the furnace and water quenched.

[0099] S2. The solution-treated sheet is cold-rolled at room temperature. The initial thickness of the sheet is 20.0 mm. After two passes of cold rolling deformation, the thickness of the sheet is reduced to 14.0 mm.

[0100] S3. The cold-deformed sheet is subjected to over-aging treatment, with the over-aging temperature set at 350℃. After the furnace reaches the desired temperature, the sheet is placed in the furnace and the holding time is calculated after the temperature stabilizes. The holding time is 12 hours. After the holding time is completed, the sheet is cooled to 300℃ and then held at 300℃ for another hour. After the holding time is completed, the sheet is taken out of the furnace and subjected to continuous warm rolling deformation. After 5 passes, the sheet is rolled into a sheet with a thickness of 4.2mm. The sheet is not reheated in the furnace during the warm rolling process.

[0101] S4. After five passes of rolling, the plate is rapidly heated to 510°C for high-temperature short-time recrystallization solution treatment. The recrystallization solution treatment is carried out in a salt bath furnace and the holding time is 10 minutes. After the holding time is completed, the plate is immediately quenched in water at room temperature and the recrystallized solution alloy is subjected to re-aging treatment to reach the peak aging state. The aging temperature is 170°C and the aging time is 12 hours.

[0102] Example 4

[0103] This embodiment provides a processing method for a high Cu content Al-Cu alloy. The difference between this embodiment and Embodiment 1 is that in step S3, the alloy is rolled into a plate with a thickness of 8.5 mm in 5 passes, while the other conditions are the same.

[0104] Comparative Example 1

[0105] This comparative example provides a traditional deformation heat treatment method for refining the grain size of high-Cu content Al-Cu alloy plates. The treatment method in this comparative example is: S1 solution quenching, S2 over-aging, S3 rolling warm deformation, and S4 high-temperature short-time recrystallization solution treatment, without cold rolling deformation. Figure 8 As shown, the specific steps are as follows:

[0106] The chemical composition of the high-Cu content Al-Cu alloy plate is Cu 6.4wt.%, Mn 0.25wt.%, Ti 0.03wt.%, Fe≤0.20wt.%, Si≤0.15wt.%, with the remainder being Al and unavoidable impurities.

[0107] S1. Solution quenching treatment is carried out on Al-Cu alloy plates with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace at a temperature of 535℃. After reaching the temperature, the plates are placed in the furnace and the holding time is calculated after the temperature stabilizes. The holding time is 2 hours. After the holding time is completed, the plates are immediately removed from the furnace and water quenched.

[0108] S2. After solution treatment, the board is subjected to over-aging treatment, with the over-aging temperature set at 425℃. After the furnace reaches the desired temperature, the board is placed in the furnace and the holding time is calculated after the temperature stabilizes. The holding time is 12 hours. After the holding time is completed, the board is removed from the furnace and air-cooled.

[0109] S3. The aged sheet material was heated to 300℃ in the furnace and held at that temperature for 2 hours. After holding, the sheet material was removed from the furnace and rolled. The initial thickness of the sheet material was 20.0 mm, and after 6 rolling passes, the thickness decreased to 4.2 mm. Table 3 shows the thickness and deformation of the sheet material before and after rolling in Comparative Example 1. The total deformation of the warm rolling in the comparative example was 75.0%. Because cracks appeared at the edge of the sheet material during the 5th rolling pass, the cracked part of the sheet material was cut off to ensure safe continuation of rolling. The sheet material was then cut longitudinally and reheated in the furnace to reduce deformation resistance. The holding temperature was 300℃, and the holding time was 1–2 hours. After holding, the cut sheet material was removed and rolled again.

[0110] S4. Rapidly heat the deformed sheet to 535℃ for high-temperature short-time recrystallization solution treatment. The recrystallization solution treatment is carried out in a salt bath furnace, and the holding time is 10 minutes; after the holding time is completed, immediately quench in water at room temperature.

[0111] Table 3 shows the thickness and deformation of the sheet metal before and after rolling in Comparative Example 1.

[0112]

[0113] Figure 8 This is a schematic diagram of the traditional deformation heat treatment process in Comparative Example 1;

[0114] Figure 9 To illustrate the grain structure of the plate material in the comparative example after recrystallization and solution treatment, the average grain size measured by the truncation method was 26.7 μm.

[0115] Figure 10The image shown is a scanning electron microscope image of the second phase of the plate material in Comparative Example 1 after conventional deformation heat treatment and aging at 170℃ for 12 hours. The coarse second phase still exists and has not been spheroidized.

[0116] As can be seen from the examples and Comparative Example 1, the grain refinement method of the present invention has a more significant effect on grain refinement than traditional deformation heat treatment, and can improve the morphology of coarse second phase, reduce its size and spheroidize it, thereby improving the impact resistance of high Cu content Al-Cu alloy plates; at the same time, the warm rolling process can be carried out continuously without secondary heating and cutting of the plate, reducing energy consumption and production time.

[0117] Comparative Example 2

[0118] This comparative example provides a traditional deformation heat treatment method for refining the grain size of high-Cu content Al-Cu alloy plates, specifically:

[0119] The chemical composition of the high Cu content Al-Cu alloy plate is Cu 6.4 wt.%, Mn 0.25 wt.%, Ti 0.03 wt.%, Fe ≤ 0.20 wt.%, Si ≤ 0.15 wt.%, with the remainder being Al and unavoidable impurities;

[0120] The high Cu content Al-Cu alloy sheet was solution treated at 475℃ for 1.5h, then water quenched at room temperature. The solution-treated sheet was then cold-rolled to a thickness of 50% to 10.0mm. The 10.0mm sheet was then held at 400℃ for 30min and then continuously deformed to a thickness of 70%. The continuous deformation process was not repeated in the furnace. The final rolled sheet was then treated at 480℃ for 0.5h and 120℃ for 24h.

[0121] Test case

[0122] The performance of the embodiments and comparative examples is shown in Table 4:

[0123] Impact resistance testing standard: GB / T 34108-2017;

[0124] Table 4. Impact resistance test data of the examples and comparative examples

[0125]

[0126] The high-Cu content Al-Cu alloy sheet prepared by this invention shows significantly improved impact strength and plasticity absorption energy compared to industrially produced T87 temper sheet. Comparative Example 1, using a conventional deformation heat treatment method, shows some improvement in strength and plasticity absorption energy compared to the T87 temper sheet, but the improvement is not significant. In Comparative Example 2, the solution temperature was lowered, preventing the second phase from dissolving into the matrix. This prevented the re-precipitation of uniformly fine and dispersed precipitates during the final aging process. Furthermore, the previously present fine precipitates coarsened and grew during the 400℃ holding period, resulting in a significant decrease in strength and plasticity absorption energy compared to the T87 temper sheet, rather than an improvement.

[0127] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method of processing a high Cu content Al-Cu alloy sheet material, characterized by: The method comprises the following steps: S1. quenching after first solution treatment of high Cu content Al-Cu alloy plate; S2. cold deformation of the quenched high Cu content Al-Cu alloy plate; S3. cooling, holding treatment and deformation after heating and overaging treatment of the cold deformed high Cu content Al-Cu alloy plate; S4. second solution treatment and aging treatment after deformation of the deformed high Cu content Al-Cu alloy plate; The high Cu content Al-Cu alloy plate has 5.5wt.%≤Cu≤7.0wt.%.

2. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: The first solution treatment has a temperature of 500-540℃; and / or, the first solution treatment has a time of 1-5h.

3. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: In step S2, the cold deformation comprises cold rolling deformation, and the deformation amount of the cold deformation is 10%-50%.

4. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: In step S3, the overaging treatment has a temperature of 350-450℃; and / or, the overaging treatment has a holding time of 6-30h.

5. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: In step S3, the temperature after cooling is 200-300℃.

6. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: In step S3, the holding treatment has a temperature of 200-300℃.

7. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: In step S3, the deformation has a deformation amount of 40%-90%; And / or, the cold deformation amount in step S2 and the deformation amount in step S3 satisfy: 60%≤δc+δw-δc*δw≤90%, wherein, δc is the cold deformation amount, which is the deformation amount of the initial thickness of the plate minus the final thickness of the cold deformation and then relative to the initial thickness, and δw is the deformation amount, which is the final thickness of the deformation minus the final thickness of the deformation and then relative to the final thickness of the cold deformation.

8. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: In step S4, the second solution treatment has a temperature of 510-540℃; and / or, the second solution treatment has a time of 10min-60min.

9. The method of processing a high-Cu-content Al-Cu alloy sheet according to claim 1, characterized by: The aging treatment has a temperature of 150-180℃; and / or, the aging treatment has a holding time of 8-120h.

10. Use of the high Cu content Al-Cu alloy plate according to any one of claims 1-9 in the preparation of aerospace components or armored components.

Images