A method of artificial aging of a naturally aged 6xxx al-based material

Abstract

The application provides an artificial aging method of a natural aging state 6xxx Al-based material, wherein the artificial aging method of the natural aging state 6xxx Al-based material comprises the following steps: heating the natural aging state 6xxx Al-based material after solid solution and quenching treatment to 170-200 DEG C at a heating rate of not higher than 2 DEG C / min; performing high-temperature artificial aging treatment on the natural aging state 6xxx Al-based material after the heating treatment at a temperature of 170-200 DEG C to obtain an under-aged state 6xxx Al-based material; cooling the under-aged state 6xxx Al-based material to 100-130 DEG C; and performing low-temperature artificial aging treatment on the under-aged state 6xxx Al-based material after the cooling treatment at a temperature of 100-130 DEG C to obtain a 6xxx Al-based material. The application controls the high-temperature artificial aging and the low-temperature artificial aging, inhibits the parking effect, promotes the transition of atomic clusters to precipitated phases, avoids the formation of coarse precipitated phases, and improves the strengthening capacity of the artificial aging of the natural aging state 6xxx Al-based material.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for metal matrix composites, specifically to an artificial aging method for naturally aged 6xxxAl-based materials. Background Technology

[0002] 6xxx series (Al-Mg-Si system) aluminum alloys possess advantages such as good corrosion resistance, light weight, and good formability. Adding reinforcing phases (such as ceramic phases, nano-carbon, etc.) to 6xxx aluminum alloys to prepare aluminum-based composite materials can further improve strength, elastic modulus, and fatigue resistance. In recent years, different grades of 6xxx aluminum alloys and their composite materials have been widely used in transportation, aerospace, and other fields.

[0003] 6xxx aluminum alloys and their composites exhibit low strength and high ductility and toughness during room temperature aging (natural aging) after solution quenching, allowing for cold forming (straightening, stamping, sheet metal work, etc.) without cracking. Subsequent artificial aging treatment can improve strength, thus meeting service requirements. Therefore, cold forming in the naturally aged state followed by artificial aging is a common process route for 6xxx aluminum alloys and their composites. This indicates that the material needs to undergo a certain period of natural aging after solution quenching and before artificial aging. Studies have shown that for 6xxx aluminum alloys and their composites, natural aging before artificial aging leads to a decrease in strength and hardness after artificial aging. This phenomenon is called the negative natural aging effect (or the aging-free period effect), which severely restricts the application of 6xxx aluminum alloys and their composites (see the literature FA Martinsen, FJH Ehlers, M. Torsæter, R. Holmestad. Reversal of the negative natural aging effect in Al-Mg-Si alloys, Acta Materialia 60 (2012) 6091-6101). Therefore, the problem to be solved is how to improve the strength of 6xxx aluminum alloys or their composites after artificial aging, even after natural aging has occurred.

[0004] The negative effects of natural aging are mainly caused by atomic clusters formed during the natural aging process. These atomic clusters, centered around quenching vacancies, remain stable in the early stages of artificial aging, leading to a decrease in free vacancy concentration and solute supersaturation, which in turn inhibits the formation of the β'' phase (the main strengthening phase in 6xxx aluminum alloys and their composites). As the artificial aging time increases, some atomic clusters can gradually evolve into precipitates, but not the β'' phase; instead, they become larger β' phases with poorer strengthening effects, resulting in reduced strength and hardness. Therefore, the key to mitigating the negative effects of natural aging lies in maximizing the transformation of atomic clusters into precipitates while avoiding coarsening of the precipitates.

[0005] Currently, some methods have been proposed to mitigate the negative effects of natural aging. For example, adding Cu can improve the stability of atomic clusters and precipitated phases, thereby increasing the strength after artificial aging. Another method is to apply pre-aging treatment after solution quenching and before natural aging to promote the formation of atomic clusters with compositions similar to the β'' phase, thus inducing the transformation of these clusters to the β'' phase during artificial aging. However, existing methods all focus on controlling the properties of naturally aged clusters. While these methods can improve the strength after artificial aging, they also have several shortcomings: adding Cu can exacerbate natural aging hardening, leading to deterioration in cold forming performance and reduced corrosion resistance; pre-aging needs to be implemented immediately after quenching, resulting in a narrow process window and a tendency for over-aging or under-aging. The former leads to intensified natural aging hardening, while the latter fails to effectively improve strength. Summary of the Invention

[0006] In view of this, the present invention provides an artificial aging method for naturally aged 6xxxAl-based materials, the main purpose of which is to enhance the artificial aging strengthening ability by controlling the artificial aging process without affecting the cold forming performance of naturally aged materials.

[0007] To address the above problems, the present invention mainly provides the following technical solutions:

[0008] On one hand, the present invention provides an artificial aging method for naturally aged 6xxxAl-based materials, wherein the 6xxxAl-based material is a 6xxx aluminum alloy or a 6xxx aluminum-based composite material; wherein the 6xxxAl-based material, after solution treatment, quenching and natural aging, is a naturally aged 6xxxAl-based material;

[0009] The artificial aging method for the naturally aged 6xxxAl-based material includes the following steps:

[0010] Heating treatment: The naturally aged 6xxxAl-based material is heated to 170~200℃ at a heating rate not exceeding 2℃ / min;

[0011] High-temperature artificial aging treatment: The naturally aged 6xxxAl-based material after the heating treatment is subjected to high-temperature artificial aging treatment at 170~200℃ until it reaches the under-aged state, to obtain the under-aged 6xxxAl-based material (it should be noted here that the "under-aged state" refers to aging to the point before the peak hardness (maximum hardness)).

[0012] Cooling treatment: The under-aged 6xxxAl-based material is cooled to 100~130℃;

[0013] Low-temperature artificial aging treatment: The under-aged 6xxxAl-based material after cooling treatment is subjected to low-temperature artificial aging treatment at a temperature of 100~130℃ to obtain 6xxxAl-based material.

[0014] Preferably, in the step of high-temperature artificial aging treatment, the high-temperature artificial aging treatment time is 0.5~4h.

[0015] Preferably, in the cooling process step:

[0016] The cooling method is as follows: first, place the under-aged 6xxxAl-based material in a room temperature environment, then lower the furnace temperature to 100~130℃, and then place the under-aged 6xxxAl-based material in the furnace for the low-temperature artificial aging treatment.

[0017] Preferably, in the cooling process step:

[0018] The cooling method is as follows: the under-aged 6xxxAl-based material is cooled to 100~130℃ in the furnace; preferably, the cooling rate is not less than 5℃ / min.

[0019] Preferably, in the step of low-temperature artificial aging treatment, the low-temperature artificial aging treatment time is 72~144h.

[0020] In another aspect, embodiments of the present invention provide a method for preparing a 6xxxAl-based material, wherein the 6xxxAl-based material is a 6xxx aluminum alloy or a 6xxx aluminum-based composite material; wherein the preparation method includes the following steps:

[0021] Step S1: Prepare 6xxxAl-based material ingots and hot process them into 6xxxAl-based profiles;

[0022] Step S2: The 6xxxAl-based profile is first subjected to solution treatment and quenching treatment, and then subjected to natural aging treatment to obtain naturally aged 6xxxAl-based material;

[0023] Step S3: The naturally aged 6xxxAl-based material is treated using any of the above-described artificial aging methods for naturally aged 6xxxAl-based materials to obtain 6xxxAl-based materials.

[0024] Preferably, in step S2:

[0025] The solution treatment temperature is 530~560℃, and the time is 0.5~3h; and / or

[0026] The quenching medium is room temperature water; and / or

[0027] During the natural aging process, the 6xxxAl-based profile can be cold-formed at any point in time to obtain the naturally aged 6xxxAl-based material.

[0028] Preferably, the 6xxx aluminum-based composite material is prepared by adding a reinforcing phase during the preparation of the 6xxx aluminum alloy; more preferably, in the 6xxx aluminum-based composite material, the volume content of the reinforcing phase is 10~40%, preferably 10~25%; more preferably, the reinforcing phase is a micron-sized ceramic phase; preferably, the micron-sized ceramic phase is at least one of SiC, Al2O3, B4C, TiC and TiB2.

[0029] Preferably, when the 6xxxAl-based material is the 6xxx aluminum-based composite material, in step S3: when performing the high-temperature artificial aging treatment: if the temperature of the high-temperature artificial aging treatment is greater than or equal to 170°C and less than 180°C, then the time of the high-temperature artificial aging treatment is greater than or equal to 2 hours and less than 3 hours; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 180°C and less than 190°C, then the time of the high-temperature artificial aging treatment is greater than or equal to 1 hour and less than 2 hours; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 190°C and less than 200°C, then the time of the high-temperature artificial aging treatment is greater than or equal to 0.5 hours and less than 1 hour; and / or, when performing the low-temperature artificial aging treatment, the time of the low-temperature artificial aging treatment is 72 to 120 hours.

[0030] Preferably, when the 6xxxAl-based material is the 6xxx aluminum alloy, in step S3: when performing the high-temperature artificial aging treatment: if the temperature of the high-temperature artificial aging treatment is greater than or equal to 170°C and less than 180°C, then the time of the high-temperature artificial aging treatment is greater than or equal to 3 hours and less than 4 hours; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 180°C and less than 190°C, then the time of the high-temperature artificial aging treatment is greater than or equal to 2 hours and less than 3 hours; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 190°C and less than 200°C, then the time of the high-temperature artificial aging treatment is greater than or equal to 1 hour and less than 2 hours.

[0031] Compared with the prior art, the artificial aging method of the present invention for naturally aged 6xxxAl-based materials has at least the following beneficial effects:

[0032] This invention provides an artificial aging method for naturally aged 6xxxAl-based materials. The method involves heating the solution-treated and quenched naturally aged 6xxxAl-based materials to 170-200°C at a rate not exceeding 2°C / min (a slow heating process). During this slow heating process, the cluster composition is sufficiently adjusted with the change in aging temperature, facilitating the transformation to the β'' phase. Then, at 170-200°C, the heated naturally aged 6xxxAl-based materials are subjected to high-temperature artificial aging treatment to a sub-aged state. Here, the β'' phase forms at a relatively high temperature, while simultaneously limiting the material's state to a sub-aged state, preventing coarsening of precipitates during aging, and ensuring that some alloying elements remain in a solution state, allowing them to continue forming fine precipitates during subsequent low-temperature aging. Finally, the under-aged 6xxxAl-based material is cooled to 100-130°C, and then subjected to low-temperature artificial aging treatment at this temperature to obtain the 6xxxAl-based material. Here, lowering the artificial aging temperature effectively solves the problem of insufficient solute precipitation, not only inhibiting the precipitation of coarse precipitates but also promoting the further transformation of residual alloying elements into fine precipitates. Therefore, in this invention, the strengthening ability of the 6xxxAl-based material is effectively enhanced through the synergistic effect of high-temperature and low-temperature artificial aging.

[0033] Compared to the traditional method of solution quenching and natural aging followed by single-stage artificial aging, the 6xxxAl-based materials treated with multi-stage artificial aging (high-temperature artificial aging and low-temperature artificial aging) exhibit significantly improved strength and hardness. The heat treatment process is simple, highly operable, and effectively broadens the applications of aluminum alloys and their composites, making it suitable for large-scale application in actual production processes. Attached Figure Description

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

[0035] Figure 1 This is a microstructure diagram of the precipitated phase corresponding to the 6xxx aluminum-based composite material in Example 1 of the present invention;

[0036] Figure 2 This is a microstructure diagram of the precipitated phase corresponding to the 6xxx aluminum-based composite material in Comparative Example 3 of the present invention;

[0037] Figure 3 This is a microstructure diagram of the precipitated phase corresponding to the 6xxx aluminum-based composite material in Comparative Example 4 of the present invention;

[0038] Figure 4 This is a microstructure diagram of the precipitated phases corresponding to the 6xxx aluminum alloy in Example 3 of the present invention;

[0039] Figure 5 This is a microstructure diagram of the precipitated phase corresponding to the 6xxx aluminum alloy in Comparative Example 5 of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] To overcome the shortcomings of existing technologies, this invention proposes an artificial aging method for naturally aged 6xxxAl-based materials. The design concept of this invention is as follows: The key to improving the artificial aging strengthening ability of naturally aged 6xxx aluminum alloys or their composites lies in promoting the transformation of atomic clusters into precipitated phases while avoiding the formation of coarse precipitated phases. During isothermal aging, atomic clusters are difficult to transform into fine β'' phases, but during temperature-increasing aging, the cluster composition can be fully adjusted with changes in aging temperature, making the transformation to the β'' phase relatively easy. Therefore, in the artificial aging process described in this invention, step (1) is slow temperature-increasing aging. Considering that the β'' phase requires holding at a relatively high temperature to form, after temperature-increasing aging, step (2) of the artificial aging process described in this invention is set to high-temperature artificial aging. Simultaneously, to avoid coarsening of the precipitated phases during aging, the 6xxxAl-based material is kept in an under-aged state by limiting the aging temperature and time. While this treatment can avoid coarsening of the precipitated phases, it inevitably leads to insufficient solute precipitation. Therefore, in the artificial aging process described in this invention, after high-temperature artificial aging, step (3) is set to low-temperature artificial aging treatment, which on the one hand inhibits the formation of coarse precipitates, and on the other hand promotes the residual alloying elements to further transform into fine precipitates.

[0042] The specific solution of this invention is as follows:

[0043] On one hand, embodiments of the present invention provide an artificial aging method for naturally aged 6xxxAl-based materials, wherein the 6xxxAl-based materials are 6xxx aluminum alloys or 6xxx aluminum-based composite materials; wherein the 6xxxAl-based materials are naturally aged 6xxxAl-based materials after solution treatment, quenching and natural aging treatment.

[0044] The artificial aging method for the naturally aged 6xxxAl-based material includes the following steps:

[0045] Heating treatment: The naturally aged 6xxxAl-based material after solution treatment and quenching is heated to 170~200℃ at a heating rate of no more than 2℃ / min (slow heating process).

[0046] High-temperature artificial aging treatment: The naturally aged 6xxxAl-based material after the initial heating treatment is subjected to high-temperature artificial aging treatment at 170~200℃ until it reaches a sub-aged state, thus obtaining a sub-aged 6xxxAl-based material. Preferably, the high-temperature artificial aging treatment time in this step is 0.5~4 hours.

[0047] Cooling treatment: The under-aged 6xxxAl-based material is cooled to 100-130°C. Preferably, in this step, the under-aged 6xxxAl-based material is first placed in a room temperature environment, the furnace temperature is lowered to 100-130°C, and then the under-aged 6xxxAl-based material is placed in the furnace for the low-temperature artificial aging treatment. Alternatively, the under-aged 6xxxAl-based material is cooled to 100-130°C in the furnace; preferably, the cooling rate is not less than 5°C / min.

[0048] Low-temperature artificial aging treatment: The under-aged 6xxxAl-based material after cooling treatment is subjected to low-temperature artificial aging treatment at a temperature of 100~130℃ to obtain 6xxxAl-based material. In this step, the low-temperature artificial aging treatment time is 72~144h.

[0049] On the other hand, embodiments of the present invention also provide a method for preparing 6xxxAl-based materials, wherein the 6xxxAl-based materials are 6xxx aluminum alloys or 6xxx aluminum-based composite materials; wherein the preparation method includes the following steps:

[0050] Step S1: Prepare 6xxxAl-based material ingots and hot process them into 6xxxAl-based profiles.

[0051] In this step, the 6xxxAl-based material ingot is a 6xxx aluminum alloy ingot or a 6xxx aluminum-based composite material ingot; preferably, the 6xxx aluminum-based composite material ingot is prepared by adding a reinforcing phase during the preparation of the 6xxx aluminum alloy ingot; more preferably, in the 6xxx aluminum-based composite material ingot, the volume content of the reinforcing phase is 10~40%, preferably 10~25%; more preferably, the reinforcing phase is a micron-sized ceramic phase; preferably, the micron-sized ceramic phase is at least one of SiC, Al2O3, B4C, TiC, and TiB2.

[0052] Step S2: The 6xxxAl-based profile is first subjected to solution treatment and quenching treatment, and then subjected to natural aging treatment to obtain naturally aged 6xxxAl-based material.

[0053] In this step, the solution treatment temperature is 530~560℃ and the time is 0.5~3h; and / or the quenching medium is room temperature water; and / or during the natural aging treatment, the 6xxxAl-based profile can be cold-formed at any time point to obtain the naturally aged 6xxxAl-based material, which has the advantages of low strength and high ductility and toughness, and is beneficial for subsequent artificial aging treatment.

[0054] Step S3: The naturally aged 6xxxAl-based material is treated using the artificial aging method for naturally aged 6xxxAl-based materials described above to obtain 6xxxAl-based material.

[0055] In this step, when the 6xxxAl-based material is the 6xxx aluminum-based composite material, the high-temperature artificial aging treatment is performed as follows: if the high-temperature artificial aging treatment temperature is greater than or equal to 170℃ and less than 180℃, the high-temperature artificial aging treatment time is greater than or equal to 2 hours and less than 3 hours; if the high-temperature artificial aging treatment temperature is greater than or equal to 180℃ and less than 190℃, the high-temperature artificial aging treatment time is greater than or equal to 1 hour and less than 2 hours; if the high-temperature artificial aging treatment temperature is greater than or equal to 190℃ and less than 200℃, the high-temperature artificial aging treatment time is greater than or equal to 0.5 hours and less than 1 hour. Through the above settings, the β'' precipitate phase is formed without coarsening it, thus ensuring the material is in an under-aged state. Furthermore, when performing the low-temperature artificial aging treatment, the low-temperature artificial aging time is 72~120 hours.

[0056] When the 6xxxAl-based material is the 6xxx aluminum alloy, the high-temperature artificial aging treatment is performed as follows: if the temperature of the high-temperature artificial aging treatment is greater than or equal to 170℃ and less than 180℃, the high-temperature artificial aging treatment time is greater than or equal to 3 hours and less than 4 hours; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 180℃ and less than 190℃, the high-temperature artificial aging treatment time is greater than or equal to 2 hours and less than 3 hours; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 190℃ and less than 200℃, the high-temperature artificial aging treatment time is greater than or equal to 1 hour and less than 2 hours. Through the above settings, the β'' precipitate phase is formed without coarsening it, thus ensuring that the material is in an under-aged state.

[0057] In summary, this invention heats the naturally aged 6xxxAl-based material after solution treatment and quenching to 170-200°C at a heating rate not exceeding 2°C / min (slow heating process). During this slow heating process, the cluster composition is sufficiently adjusted with changes in aging temperature, facilitating the transformation to the β'' phase. Then, at 170-200°C, the heated naturally aged 6xxxAl-based material is subjected to high-temperature artificial aging treatment to a sub-aged state. Here, the β'' phase forms at a relatively high temperature, preventing coarsening of the precipitated phase during aging and also limiting the material's state to a sub-aged state. Finally, the sub-aged 6xxxAl-based material is cooled to 100-130°C, and then subjected to low-temperature artificial aging treatment at 100-130°C to obtain the 6xxxAl-based material. Here, reducing artificial aging effectively solves the problem of insufficient solute precipitation, not only inhibiting the precipitation of coarse precipitates but also promoting the further transformation of residual alloying elements into fine precipitates. Therefore, in this invention, the strengthening ability of 6xxxAl-based materials is effectively enhanced through the synergistic effect of high-temperature and low-temperature artificial aging. Compared to the traditional method of applying single-stage artificial aging after solution quenching and natural aging, the 6xxxAl-based materials treated with multi-stage artificial aging (high-temperature and low-temperature artificial aging) of this invention show significant improvements in both strength and hardness. The heat treatment process is simple, highly operable, and effectively broadens the application of aluminum alloys and their composites, making it suitable for large-scale application in actual production processes.

[0058] The present invention will be further illustrated below with specific embodiments:

[0059] Example 1

[0060] This embodiment provides a method for preparing 6xxx aluminum-based composite materials (using 6xxx aluminum alloy as the matrix), including the following steps:

[0061] 1) Preparation of 6xxx aluminum-based composite ingots: In the raw materials, the reinforcing phase is SiC particles with an average particle size of 5μm, with a volume fraction of 20%. By mass percentage, the aluminum matrix contains 1.30wt% Mg, 0.50wt% Si, and the balance is Al.

[0062] The above raw materials were prepared into 6xxx aluminum-based composite material ingots using powder metallurgy, and then hot-extruded into bars. The hot-pressing temperature was 450°C, and the hot-extrusion ratio was 15:1.

[0063] 2) The 6xxx aluminum-based composite rods were first solution-treated at 535±5°C for 2.5 hours, quenched to room temperature, and then subjected to natural aging treatment for 7 days to obtain the naturally aged 6xxx aluminum-based composite material.

[0064] 3) Place the naturally aged 6xxx aluminum-based composite material in the furnace and heat it to 170℃ at a heating rate of 2℃ / min.

[0065] 4) At a temperature of 170℃, the naturally aged 6xxx aluminum-based composite material is subjected to high-temperature artificial aging treatment for 2 hours to reach the under-aged state, thereby obtaining the under-aged 6xxx aluminum-based composite material.

[0066] 5) Remove the under-aged 6xxx aluminum-based composite material from the furnace and place it in a room temperature environment. After the furnace temperature is reduced to 120°C, place the under-aged 6xxx aluminum-based composite material back into the furnace.

[0067] 6) At a temperature of 120℃, the under-aged 6xxx aluminum-based composite material, cooled to 120℃, is subjected to low-temperature artificial aging treatment for 120h to obtain the 6xxx aluminum-based composite material.

[0068] The precipitated phases of the 6xxx aluminum-based composite material obtained in this embodiment were tested, and the results are as follows: Figure 1 As shown, from Figure 1 As can be seen from this, the precipitated phases in the 6xxx aluminum-based composite material prepared in this embodiment are fine and dense, and are dispersed in the aluminum matrix.

[0069] Tensile tests were performed on the 6xxx aluminum-based composite material obtained in this embodiment, and the test results are shown in Table 1. The yield strength at room temperature was 360 MPa, and the tensile strength was 430 MPa.

[0070] Comparative Example 1

[0071] The only difference between this comparative example and Example 1 is that:

[0072] Only steps 1)-4) of Example 1 are performed, excluding steps 5) and 6) of Example 1.

[0073] Tensile tests were conducted on the 6xxx aluminum-based composite material obtained in Example 1, and the test results are shown in Table 1. The yield strength at room temperature was 310 MPa, and the tensile strength was 380 MPa.

[0074] It can be seen that the yield strength and tensile strength of the 6xxx aluminum-based composite material prepared in Comparative Example 1 are lower than those in Example 1. Therefore, it can be concluded that the low-temperature artificial aging treatment in steps 5) and 6) of Example 1 plays an important role in improving the strength.

[0075] Comparative Example 2

[0076] The only difference between this comparative example and Example 1 is that:

[0077] In step 3), the naturally aged 6xxx aluminum-based composite material is placed directly into a furnace at 170°C.

[0078] The other steps are exactly the same.

[0079] Tensile tests were conducted on the 6xxx aluminum-based composite material obtained in Example 2, and the test results are shown in Table 1. The yield strength at room temperature was 350 MPa, and the tensile strength was 415 MPa.

[0080] It can be seen that the yield strength and tensile strength of the 6xxx aluminum-based composite material prepared in Comparative Example 2 are lower than those in Example 1. Therefore, it can be concluded that the heating rate in step 3) plays an important role in improving the strength of the 6xxx aluminum-based composite material.

[0081] Comparative Example 3

[0082] The only difference between this comparative example and Example 1 is that:

[0083] In step 3), the naturally aged 6xxx aluminum-based composite material is placed directly into a furnace at 170°C.

[0084] In step 4), the 6xxx aluminum-based composite material is subjected to high-temperature artificial aging treatment at 170℃ for 2 hours until it reaches a sub-aged state, thus obtaining the 6xxx aluminum-based composite material.

[0085] Steps 5 and 6 were not performed.

[0086] The other steps are exactly the same.

[0087] The precipitated phases of the 6xxx aluminum-based composite material obtained in Example 3 were tested, and the results are as follows: Figure 2 As shown, from Figure 2 As can be seen from the data, the precipitated phase in the 6xxx aluminum-based composite material prepared in Comparative Example 3 is sparsely distributed and its content is much lower than that in the standard. Figure 1 The precipitated phase in the middle.

[0088] It is evident that, compared to the aging process of the present invention used in Example 1, Comparative Example 3, which employs a traditional artificial aging process, cannot guarantee that the number of precipitates can be increased without coarsening the precipitates, thereby improving the strength.

[0089] Tensile tests were conducted on the 6xxx aluminum-based composite material obtained in Example 3, and the test results are shown in Table 1. The yield strength at room temperature was 290 MPa, and the tensile strength was 360 MPa.

[0090] It is evident that the yield strength and tensile strength of the 6xxx aluminum-based composite material prepared in Comparative Example 3 are not only lower than those in Example 1, but also lower than those in Comparative Examples 1 and 2.

[0091] Comparative Example 4

[0092] The only difference between this comparative example and Example 1 is that:

[0093] In step 4), the 6xxx aluminum-based composite material is subjected to high-temperature artificial aging treatment at 170℃ for 6 hours until it reaches the peak aging state, thus obtaining the 6xxx aluminum-based composite material.

[0094] The other steps are exactly the same.

[0095] The precipitated phases of the 6xxx aluminum-based composite material obtained in this comparative example were tested, and the results are as follows: Figure 3 As shown, from Figure 3 It can be seen from this that: with Figure 1 compared to, Figure 3 The precipitated phase in the middle is coarser.

[0096] The 6xxx aluminum-based composite material obtained in this comparative example was subjected to tensile testing at room temperature, and the results are shown in Table 1. The yield strength at room temperature was 340 MPa, and the tensile strength was 400 MPa, which are lower than those in Example 1. It can be seen that in Comparative Example 4, the high-temperature aging process did not achieve the desired under-aging state, resulting in larger precipitated phase sizes and reduced strength.

[0097] Example 2

[0098] The only difference between this embodiment and Embodiment 1 is that:

[0099] In step 2), the 6xxx aluminum-based composite rods were solution-treated at 535±5°C for 2.5 hours, quenched to room temperature, and then subjected to natural aging treatments for 3 days, 14 days, 30 days, and 180 days to obtain the corresponding naturally aged 6xxx aluminum-based composite materials.

[0100] The other steps are exactly the same.

[0101] The 6xxx aluminum-based composite materials prepared in this embodiment exhibit similar yield strength and tensile strength at room temperature. Tensile tests were performed on the 6xxx aluminum-based composite materials obtained in this embodiment, and the results are shown in Table 1. Specifically, the material aged for 3 days has a yield strength of 365 MPa and a tensile strength of 433 MPa at room temperature; the material aged for 14 days has a yield strength of 360 MPa and a tensile strength of 428 MPa at room temperature; the material aged for 30 days has a yield strength of 358 MPa and a tensile strength of 431 MPa at room temperature; and the material aged for 180 days has a yield strength of 353 MPa and a tensile strength of 420 MPa at room temperature.

[0102] As can be seen, since the yield strength and tensile strength of the 6xxx aluminum-based composite material prepared in this embodiment are similar at room temperature, it indicates that the 6xxx aluminum-based composite material billet can be cold-formed at any time point during natural aging treatment. The 6xxx aluminum-based composite materials with different natural aging treatment times have similar yield strength and tensile strength, all showing good results.

[0103] Example 3

[0104] This embodiment provides a method for preparing 6xxx aluminum alloy, including the following steps:

[0105] 1) Preparation of 6xxx aluminum alloy billet: by mass percentage, Mg content is 0.9wt%, Si content is 0.75wt%, and the balance is Al.

[0106] The above raw materials were prepared into 6xxx aluminum alloy ingots by powder metallurgy. The ingots were hot forged at 450°C with a forging ratio of 10:1, followed by stress annealing at 480°C for 2 hours to obtain 6xxx aluminum alloy forging ingots.

[0107] 2) The 6xxx aluminum alloy forging ingot was first dissolved at 550±5°C for 0.5h, quenched to room temperature, and then subjected to natural aging treatment for 7d to obtain the naturally aged 6xxx aluminum alloy.

[0108] 3) Place the naturally aged 6xxx aluminum alloy in the furnace and heat it to 170℃ at a heating rate of 2℃ / min.

[0109] 4) At a temperature of 170℃, the naturally aged 6xxx aluminum alloy is subjected to high-temperature artificial aging treatment for 3 hours to obtain the under-aged 6xxx aluminum alloy.

[0110] 5) Remove the under-aged 6xxx aluminum alloy from the furnace and place it in a room temperature environment. After the furnace temperature is reduced to 120°C, put the under-aged 6xxx aluminum alloy back into the furnace.

[0111] 6) At 120℃, the under-aged 6xxx aluminum alloy cooled to 120℃ is subjected to low-temperature artificial aging treatment for 140h to obtain 6xxx aluminum alloy.

[0112] The precipitated phases of the 6xxx aluminum alloy obtained in Example 3 were tested, and the results are as follows: Figure 4 As shown, from Figure 4 As can be seen, the precipitated phases are fine and dense, and dispersed throughout the aluminum matrix. Tensile tests were performed on the 6xxx aluminum alloy obtained in this embodiment, and the results are shown in Table 1. The yield strength at room temperature is 243 MPa, and the tensile strength is 320 MPa.

[0113] Comparative Example 5

[0114] The only difference between this comparative example and Example 3 is that:

[0115] In step 3), the naturally aged 6xxx aluminum alloy is placed directly into a furnace at 170°C.

[0116] In step 4), the naturally aged 6xxx aluminum alloy, heated to 170°C, is subjected to high-temperature artificial aging treatment for 3 hours to reach the under-aged state, thus obtaining the under-aged 6xxx aluminum alloy.

[0117] Steps 5 and 6 were not performed.

[0118] The other steps are exactly the same.

[0119] The precipitated phases of the 6xxx aluminum alloy obtained in Example 5 were tested, and the results are as follows: Figure 5 As shown, from Figure 5 It can be seen from this that the precipitated phase is sparsely distributed and its content is far less than that of the precipitated phase. Figure 4 The precipitated phase in the middle.

[0120] Tensile tests were performed on the 6xxx aluminum alloy obtained in Example 5, and the test results are shown in Table 1. The yield strength at room temperature was 180 MPa, and the tensile strength was 280 MPa.

[0121] It is evident that the yield strength and tensile strength of the 6xxx aluminum alloy prepared in Comparative Example 5 are both lower than those in Example 3.

[0122] Table 1 Mechanical properties of 6xxx aluminum alloys and their composites

[0123]

[0124] In summary, the 6xxx aluminum alloy treated by this invention exhibits a yield strength greater than 240 MPa and a tensile strength greater than 315 MPa at room temperature; the 6xxx aluminum-based composite material treated by this process exhibits a yield strength greater than 355 MPa and a tensile strength greater than 420 MPa at room temperature. This invention, through the synergistic effect of high-temperature artificial aging (controlled heating rate, under-aging state) and low-temperature artificial aging, improves the strengthening ability of the material, and its performance is superior to existing products.

[0125] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for the production of a 6xxx Al-based material, characterized in that, The preparation method comprises the following steps: Step S1: preparing a 6xxx Al-based material billet and hot working into a 6xxx Al-based profile; Step S2: first performing solid solution treatment and quenching treatment on the 6xxx Al-based profile, and then performing natural aging treatment to obtain a natural aging state 6xxx Al-based material; Step S3: treating the natural aging state 6xxx Al-based material by using an artificial aging method of the natural aging state 6xxx Al-based material to obtain a 6xxx Al-based material; The 6xxx Al-based material is a 6xxx aluminum alloy or a 6xxx aluminum matrix composite material; the artificial aging method of the natural aging state 6xxx Al-based material comprises the following steps: temperature rising treatment: rising the temperature of the natural aging state 6xxx Al-based material at a temperature rising rate of not higher than 2 ℃ / min to 170-200 ℃; in the temperature rising process, the cluster component of the natural aging state 6xxx Al-based material is adjusted sufficiently with the change of the aging temperature, and is easy to transform into a β'' phase; high-temperature artificial aging treatment: performing high-temperature artificial aging treatment on the natural aging state 6xxx Al-based material after the temperature rising treatment at a temperature of 170-200 ℃ to an under-aged state to obtain an under-aged state 6xxx Al-based material; temperature falling treatment: falling the temperature of the under-aged state 6xxx Al-based material to 100-130 ℃; low-temperature artificial aging treatment: performing low-temperature artificial aging treatment on the under-aged state 6xxx Al-based material after the temperature falling treatment at a temperature of 100-130 ℃ to obtain a 6xxx Al-based material; When the 6xxx Al-based material is the 6xxx aluminum matrix composite material, in the step S3: when the high-temperature artificial aging treatment is performed: if the temperature of the high-temperature artificial aging treatment is greater than or equal to 170 ℃ and less than 180 ℃, the time of the high-temperature artificial aging treatment is greater than or equal to 2 h and less than 3 h; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 180 ℃ and less than 190 ℃, the time of the high-temperature artificial aging treatment is greater than or equal to 1 h and less than 2 h; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 190 ℃ and less than 200 ℃, the time of the high-temperature artificial aging treatment is greater than or equal to 0.5 h and less than 1 h; When the 6xxx Al-based material is the 6xxx aluminum alloy, in the step S3: when the high-temperature artificial aging treatment is performed: if the temperature of the high-temperature artificial aging treatment is greater than or equal to 170 ℃ and less than 180 ℃, the time of the high-temperature artificial aging treatment is greater than or equal to 3 h and less than 4 h; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 180 ℃ and less than 190 ℃, the time of the high-temperature artificial aging treatment is greater than or equal to 2 h and less than 3 h; if the temperature of the high-temperature artificial aging treatment is greater than or equal to 190 ℃ and less than 200 ℃, the time of the high-temperature artificial aging treatment is greater than or equal to 1 h and less than 2 h.

2. The method of making a 6xxx Al-based material according to claim 1, wherein, In the step of the temperature falling treatment: The cooling method is that the under-aged 6xxx Al-based material is first placed in a room temperature environment, and then the furnace temperature is reduced to 100-130 ℃, and then the under-aged 6xxx Al-based material is placed in the furnace for the low-temperature artificial aging treatment.

3. The method of making a 6xxx Al-based material according to claim 1, wherein, In the step of the cooling treatment: The cooling method is that the under-aged 6xxx Al-based material is cooled with the furnace to 100-130 ℃; wherein the cooling rate is not less than 5 ℃ / min.

4. The method of making a 6xxx Al-based material of claim 1, wherein, In the step of the low-temperature artificial aging treatment: The time of the low-temperature artificial aging treatment is 72-144 h.

5. The method of making a 6xxx Al-based material of claim 1, wherein, In the step S2: The temperature of the solution treatment is 530-560 ℃, and the time is 0.5-3 h; and / or The medium of the quenching treatment is room temperature water; and / or During the natural aging treatment, the 6xxx Al-based profile can be subjected to cold forming treatment at any time point to obtain the natural aging 6xxx Al-based material.

6. The method of making a 6xxx Al-based material of claim 1, wherein, The 6xxx Al-based composite material is prepared by adding a reinforcing phase in the preparation process of the 6xxx Al alloy.

7. The method of making a 6xxx Al-based material according to claim 6, wherein, In the 6xxx Al-based composite material, the volume content of the reinforcing phase is 10-40%.

8. The method of making a 6xxx Al-based material according to claim 7, wherein, In the 6xxx Al-based composite material, the volume content of the reinforcing phase is 10-25%.

9. The method of making a 6xxx Al-based material according to claim 6, wherein, The reinforcing phase is a micron ceramic phase.

10. The method of making a 6xxx Al-based material according to claim 9, wherein, The micron ceramic phase is at least one of SiC, Al2O3, B4C, TiC and TiB2.

11. The method of making a 6xxx Al-based material of claim 1, wherein, When the 6xxx Al-based material is the 6xxx Al-based composite material, in the step S3: When the low-temperature artificial aging treatment is performed, the time of the low-temperature artificial aging is 72-120 h.

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