Aluminum alloy non-isothermal aging treatment method and application

Abstract

The application belongs to the technical field of heat treatment process of aluminum alloy, and discloses a non-isothermal aging treatment method for aluminum alloy and application. The non-isothermal aging treatment method for aluminum alloy comprises the following steps: sequentially performing solid solution treatment, quenching treatment, first-stage non-isothermal aging treatment and second-stage non-isothermal aging treatment on the aluminum alloy. The application can regulate the structure state of the aluminum alloy in a short time, greatly shortens the aging time, improves the production efficiency, and obtains better corrosion performance than traditional aging T6 and T73.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment technology for aluminum alloys, and specifically relates to a method and application of non-isothermal aging treatment for aluminum alloys. Background Technology

[0002] Heat-treatable aluminum alloys (such as Al-Zn-Mg-Cu alloys) are ultra-high-strength aluminum alloys that can be strengthened by heat treatment. They have advantages such as low density, high strength, and easy processing. They are important structural materials for aerospace, rail transportation, and weaponry, and play an extremely important role in economic and social development and national defense modernization.

[0003] Currently, the traditional heat treatment processes for this type of alloy mainly involve T6 and T7X treatments, but both have significant limitations: While T6 treatment can bring the alloy to its peak strength, the grain boundary precipitates are mostly continuously distributed, and the non-precipitate precipitate band is too large, resulting in poor corrosion resistance; T7X treatment improves corrosion resistance by adjusting aging parameters, but at the cost of a 15-20% loss in strength, making it difficult to balance mechanical properties and corrosion resistance. Furthermore, both T6 and T7X treatments require long holding or heating / cooling times (such as long-term isothermal aging, slow heating / cooling, etc.), leading to long production cycles and low efficiency, making it difficult to meet the demands of modern industry for high-efficiency production. Summary of the Invention

[0004] The present invention aims to improve at least one technical problem in the prior art.

[0005] The first aspect of this invention provides a method for non-isothermal aging treatment of aluminum alloys, comprising the following steps:

[0006] The aluminum alloy was subjected to solution treatment, quenching treatment, first-stage non-isothermal aging treatment and second-stage non-isothermal aging treatment in sequence.

[0007] The first-level non-isothermal aging treatment includes the following steps: heating to a first temperature at a first rate, then heating to a second temperature at a second rate, then cooling to a first temperature at a second rate, and finally cooling to room temperature at a first rate.

[0008] The secondary non-isothermal aging treatment includes the following steps: heating to a first temperature at a first rate, then heating to a second temperature at a second rate, and then cooling to room temperature at a second rate.

[0009] The first temperature is 110℃-130℃, the second temperature is 180℃-210℃, the first rate is 0.5℃ / min-1℃ / min, and the second rate is 2℃ / min-5℃ / min.

[0010] Preferably, the solution treatment includes the following steps: heating to the solution treatment temperature and holding at that temperature;

[0011] The solution treatment temperature is 450℃-490℃, and the heat preservation time is 1h-2h.

[0012] Preferably, the quenching process includes the following steps: transferring the aluminum alloy that has undergone solution treatment to a fluid and cooling it to room temperature;

[0013] The fluid is water or an organic quenching fluid.

[0014] Preferably, the time from completing the solution treatment to completing the transfer does not exceed 10 seconds.

[0015] Preferably, the first-stage non-isothermal aging treatment is an incomplete aging treatment.

[0016] Preferably, if the aluminum alloy product obtained after the second-level non-isothermal aging treatment is not in a fully aged state, the third-level non-isothermal aging treatment is repeated until the aluminum alloy product reaches a fully aged state; the steps of the third-level non-isothermal aging treatment are the same as the steps of the first-level non-isothermal aging treatment.

[0017] Preferably, the aluminum alloy is an Al-Zn-Mg-Cu alloy.

[0018] The second aspect of this invention provides the application of the above-described non-isothermal aging treatment method for aluminum alloys in aluminum alloy processing.

[0019] The beneficial effects of this invention are as follows: This invention enables aluminum alloys to promote the nucleation of precipitates through slow temperature rise and fall, control the size of precipitates through rapid temperature rise and fall, and further increase the density of precipitates through secondary aging. After the aluminum alloy is treated with the method of this invention to promote the secondary aging precipitation of precipitates, the intragranular precipitates of the alloy grow moderately, the grain boundary precipitates are discontinuously distributed, and there is no wide precipitate band. After the two-stage non-isothermal aging treatment, the alloy undergoes obvious static recrystallization, and obtains equiaxed grains with uniform size. This invention enables aluminum alloys to obtain a suitable microstructure in a short time, significantly shortens the aging time, improves production efficiency, and obtains better corrosion performance than traditional aging methods T6 and T73. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of a non-isothermal aging treatment method for aluminum alloys according to one embodiment;

[0021] Figure 2 Metallographic images of the aged aluminum alloy obtained by the non-isothermal aging treatment method of aluminum alloy in Example 1 are shown.

[0022] Figure 3The image shows a scanning electron microscope (SEM) image of the aged aluminum alloy obtained by the non-isothermal aging treatment method of Example 1.

[0023] Figure 4 The image shows a transmission electron microscope (TEM) image of the matrix of the aged aluminum alloy obtained by the non-isothermal aging treatment method of Example 1.

[0024] Figure 5 Transmission electron microscopy (TEM) images of grain boundaries of the aged aluminum alloy obtained by the non-isothermal aging treatment method of Example 1.

[0025] Figure 6 Metallographic images of the aged aluminum alloy obtained by the aluminum alloy treatment method of Comparative Example 1 are shown.

[0026] Figure 7 The image shows a scanning electron microscope (SEM) image of the aged aluminum alloy obtained by the aluminum alloy treatment method of Comparative Example 1.

[0027] Figure 8 Transmission electron microscopy (TEM) images of grain boundaries of the aged aluminum alloy obtained by the aluminum alloy treatment method of Comparative Example 1.

[0028] Figure 9 Metallographic images of the aged aluminum alloy obtained by the aluminum alloy treatment method of Comparative Example 2 are shown.

[0029] Figure 10 The image shows a scanning electron microscope (SEM) image of the aged aluminum alloy obtained by the aluminum alloy treatment method of Comparative Example 2.

[0030] Figure 11 The polarization curves are obtained from electrochemical corrosion performance testing.

[0031] Figure 12 The self-corrosion current density and self-corrosion potential are obtained by fitting the polarization curve. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0033] This invention provides a non-isothermal aging treatment method for aluminum alloys. Its purpose is to shorten the aging time while ensuring that, after secondary precipitation, the intragranular precipitates grow appropriately, the grain boundary precipitates are discontinuously distributed, and a suitable width of the precipitation-free band is obtained. Furthermore, after two-stage non-isothermal aging, the alloy undergoes static recrystallization, resulting in uniformly sized equiaxed grains. This invention enables the aluminum alloy to achieve a suitable microstructure in a relatively short time, significantly shortening the aging time, improving production efficiency, and achieving better corrosion resistance than traditional aging methods T6 and T73.

[0034] refer to Figure 1 The non-isothermal aging treatment method for aluminum alloys includes the following steps:

[0035] The aluminum alloy was subjected to solution treatment, quenching treatment, first-stage non-isothermal aging treatment and second-stage non-isothermal aging treatment in sequence (solution treatment, first-stage non-isothermal aging treatment and second-stage non-isothermal aging treatment were carried out in a heat treatment furnace).

[0036] The first-level non-isothermal aging treatment includes the following steps: heating to a first temperature at a first rate, then heating to a second temperature at a second rate, then cooling to a first temperature at a second rate, and finally cooling to room temperature at a first rate.

[0037] The secondary non-isothermal aging treatment includes the following steps: heating to a first temperature at a first rate, then heating to a second temperature at a second rate, and then cooling to room temperature at a second rate.

[0038] The first temperature is 110℃-130℃, the second temperature is 180℃-210℃, the first rate is 0.5℃ / min-1℃ / min, and the second rate is 2℃ / min-5℃ / min.

[0039] Figure 1 In this context, T0 represents the solution treatment temperature, Ta represents the first temperature, Tb represents the second temperature, Vc represents the first rate, and Vd represents the second rate.

[0040] This non-isothermal aging treatment method for aluminum alloys involves a sequential process of solution treatment, quenching, first-stage non-isothermal aging, and second-stage non-isothermal aging, forming a complete performance control system. Solution treatment fully dissolves the strengthening phases (such as MgZn2 and Al2CuMg phases commonly found in heat-treatable aluminum alloys) into the aluminum matrix, forming a homogeneous supersaturated solid solution, providing a foundation for precipitation strengthening in the subsequent aging stage. Quenching rapidly cools the solution-treated aluminum alloy to room temperature, suppressing the diffusion and premature precipitation of solute atoms in the supersaturated solid solution, maintaining its high-energy supersaturated state, and providing sufficient driving force for the uniform precipitation of strengthening phases during the aging process. The first-stage non-isothermal aging treatment first raises the temperature to a first temperature of 110℃-130℃ at a first rate of 0.5℃ / min-1℃ / min. This combination of a low temperature range and a slow heating rate promotes the formation of a large number of fine and uniform precipitate nuclei, laying a uniform nucleation foundation for the subsequent growth of precipitates. Then, the temperature is raised to a second temperature of 180℃-210℃ at a second rate of 2℃ / min-5℃ / min. This combination of a high temperature range and a faster heating rate ensures normal growth of the precipitates while preventing them from becoming excessively coarsened, and also promotes the transformation of some unstable precipitates into more stable strengthening phases. Subsequently, the temperature is lowered to the first temperature at the second rate, and then to room temperature at the first rate. This cooling process further consolidates the distribution of the precipitates and reduces the tissue stress caused by sudden temperature changes. The secondary non-isothermal aging process, based on the primary aging process, further increases the density of precipitates and optimizes their spatial distribution through low-temperature nucleation and high-temperature control. This process causes the grain boundary precipitates to change from a continuous distribution in traditional processes to a discontinuous distribution. At the same time, it adjusts the width of the non-precipitate precipitate band to a reasonable range. In addition, the temperature cycling during the secondary aging process can induce static recrystallization of the aluminum alloy, refine the grains, and form uniform equiaxed grains, providing microstructure assurance for the improvement of overall performance.

[0041] Preferably, the solution treatment includes the following steps: heating to the solution treatment temperature and holding at that temperature;

[0042] The solution treatment temperature is 450℃-490℃, and the heat preservation time is 1h-2h.

[0043] Preferably, the quenching process includes the following steps: transferring the aluminum alloy that has undergone solution treatment to a fluid and cooling it to room temperature;

[0044] The fluid is water or an organic quenching fluid.

[0045] The preferred fluid is water or organic quenching fluid, both of which have high cooling rates, meeting the core requirement of rapid cooling in quenching treatment, effectively suppressing the premature precipitation of supersaturated solid solutions during the cooling process, and maximizing the preservation of the supersaturated state formed by the solution treatment.

[0046] Preferably, the time from completing the solution treatment to completing the transfer does not exceed 10 seconds.

[0047] If the transfer time is too long, the aluminum alloy will naturally cool in the air after being taken out of the solution furnace, causing the surface and internal temperatures to drop rapidly. This leads to the premature precipitation of supersaturated solid solutions, forming non-uniformly distributed precipitates that disrupt the uniformity of the microstructure before aging and ultimately affect the strengthening effect of subsequent aging treatments. Controlling the transfer time to no more than 10 seconds can minimize the exposure time of the aluminum alloy in the air, ensuring that it maintains a relatively high temperature when entering the quenching fluid, guaranteeing the timeliness and effectiveness of quenching and cooling, and maintaining the uniformity of the microstructure.

[0048] Preferably, the first-stage non-isothermal aging treatment is an incomplete aging treatment.

[0049] The first-level non-isothermal aging treatment is an incomplete aging treatment. It only completes the function of "nucleation and preliminary growth of the precipitated phase" rather than reaching the final performance state. By retaining some unprecipitated solute atoms through incomplete aging, it provides material reserves for the "supplementary precipitation" of the second-level non-isothermal aging treatment, and avoids performance defects caused by excessive growth or uneven distribution of the precipitated phase during a single aging process.

[0050] Preferably, if the aluminum alloy product obtained after the second-level non-isothermal aging treatment is not in a fully aged state, the third-level non-isothermal aging treatment is repeated until the aluminum alloy product reaches a fully aged state; the steps of the third-level non-isothermal aging treatment are the same as the steps of the first-level non-isothermal aging treatment.

[0051] In response to differences in aluminum alloy composition, different original microstructure, or process fluctuations during batch processing, when the product fails to reach full aging state after secondary non-isothermal aging treatment due to the above factors (such as insufficient precipitate density or substandard corrosion resistance), the product can be brought to full aging state by repeating tertiary non-isothermal aging treatment (the low-temperature nucleation and high-temperature control steps of the same primary non-isothermal aging treatment). This can specifically supplement the amount of precipitates and optimize the microstructure, thereby improving the stability of the process and the consistency of the product.

[0052] Preferably, the aluminum alloy is an Al-Zn-Mg-Cu alloy.

[0053] The present invention will be described with reference to specific embodiments and comparative examples:

[0054] The aluminum alloy used in the examples and comparative examples is an Al-Zn-Mg-Cu alloy, specifically a 7075 aluminum alloy, with the following mass composition: zinc 5.1%-6.1%, magnesium 2.1%-2.9%, copper 1.2%-2%, iron 0.5%, silicon 0.4%, manganese 0.3%, chromium 0.18%-0.28%, titanium 0.2%, and the balance being aluminum.

[0055] First, it should be noted that the main strengthening mechanism of 7075 aluminum alloy is precipitation strengthening, primarily composed of shear and Orowan strengthening mechanisms. The shear mechanism improves alloy strength by dislocation shearing precipitates, mainly through coherent GP zones and semi-coherent η' phase strengthening. The Orowan strengthening mechanism refers to the phenomenon where, when the size of the precipitates reaches a certain level, dislocations can only bypass the precipitates, thus improving the alloy's strength to some extent; this is mainly due to coherent η phase strengthening. The shear mechanism is superior to the Orowan strengthening mechanism. Simultaneously, static recrystallization of the alloy results in uniformly sized equiaxed grains, which also improves the alloy's mechanical properties. Secondly, corrosion of aluminum alloys generally preferentially occurs along grain boundaries. Grain boundary precipitates, typically coarse and discontinuously distributed, hinder grain boundary corrosion. The formation and growth of grain boundary precipitates consume solute atoms near the grain boundaries, leading to the appearance and widening of non-precipitated zones. A moderately sized PFZ (non-precipitated zone) can improve corrosion resistance; above a critical value, corrosion resistance increases with the width of the non-precipitated phase.

[0056] Example 1

[0057] A method for non-isothermal aging treatment of aluminum alloys includes the following steps:

[0058] The aluminum alloy was subjected to solution treatment, quenching treatment, first-stage non-isothermal aging treatment and second-stage non-isothermal aging treatment in sequence.

[0059] The solution treatment includes the following steps: heating to 470℃ (solution treatment temperature) and holding at that temperature for 1 hour;

[0060] The quenching process includes the following steps: transferring the aluminum alloy that has undergone solution treatment to pure water (fluid) to cool to room temperature (the time from the completion of solution treatment to the completion of transfer should not exceed 10 seconds);

[0061] The first-level non-isothermal aging treatment includes the following steps: heating from room temperature to 130°C (first temperature) at a rate of 1°C / min (first rate), then heating from 130°C to 190°C (second temperature) at a rate of 5°C / min (second rate), then cooling from 190°C to 130°C (first temperature) at a rate of 5°C / min (second rate), and finally cooling from 130°C (first temperature) to room temperature at a rate of 1°C / min (first rate).

[0062] The secondary non-isothermal aging treatment includes the following steps: heating from room temperature to 130°C (first temperature) at a rate of 1°C / min (first rate), then heating from 130°C to 190°C (second temperature) at a rate of 5°C / min (second rate), and then cooling from 190°C (second temperature) to room temperature at a rate of 5°C / min (second rate).

[0063] The metallographic image of the aged aluminum alloy obtained by the non-isothermal aging treatment method of Example 1 is shown below. Figure 2 As shown, its scanning electron microscope image is as follows: Figure 3 As shown, the transmission electron microscope image of its substrate is as follows: Figure 4 As shown, the transmission electron microscope image at its grain boundaries is as follows: Figure 5 As shown.

[0064] Comparative Example 1

[0065] A method for processing aluminum alloys includes the following steps:

[0066] The aluminum alloy was subjected to solution treatment, quenching treatment and first-level non-isothermal aging treatment in sequence.

[0067] The solution treatment includes the following steps: heating to 470℃ (solution treatment temperature) and holding at that temperature for 1 hour;

[0068] The quenching process includes the following steps: transferring the aluminum alloy that has undergone solution treatment to pure water (fluid) to cool to room temperature (the time from the completion of solution treatment to the completion of transfer should not exceed 10 seconds);

[0069] The first-level non-isothermal aging treatment includes the following steps: heating from room temperature to 130°C (first temperature) at a rate of 1°C / min (first rate), then heating from 130°C to 190°C (second temperature) at a rate of 5°C / min (second rate), then cooling from 190°C to 130°C (first temperature) at a rate of 5°C / min (second rate), and finally cooling from 130°C (first temperature) to room temperature at a rate of 1°C / min (first rate).

[0070] The metallographic image of the aging aluminum alloy obtained by the aluminum alloy treatment method in Comparative Example 1 is shown below. Figure 6 As shown, its scanning electron microscope image is as follows: Figure 7 As shown, the transmission electron microscope image at its grain boundaries is as follows: Figure 8 As shown.

[0071] Comparative Example 2

[0072] A method for processing aluminum alloys includes the following steps:

[0073] The aluminum alloy was subjected to solution treatment, quenching treatment, first-stage non-isothermal aging treatment and second-stage aging treatment in sequence.

[0074] The solution treatment includes the following steps: heating to 470℃ (solution treatment temperature) and holding at that temperature for 1 hour;

[0075] The quenching process includes the following steps: transferring the aluminum alloy that has undergone solution treatment to pure water (fluid) to cool to room temperature (the time from the completion of solution treatment to the completion of transfer should not exceed 10 seconds);

[0076] The first-level non-isothermal aging treatment includes the following steps: heating from room temperature to 130°C (first temperature) at a rate of 1°C / min (first rate), then heating from 130°C to 190°C (second temperature) at a rate of 5°C / min (second rate), then cooling from 190°C to 130°C (first temperature) at a rate of 5°C / min (second rate), and finally cooling from 130°C (first temperature) to room temperature at a rate of 1°C / min (first rate).

[0077] The secondary aging process includes the following steps: heating from room temperature to 130°C at a rate of 1°C / min, and then transferring to pure water to cool to room temperature (the transfer time should not exceed 10 seconds).

[0078] The metallographic image of the aging aluminum alloy obtained by the aluminum alloy treatment method in Comparative Example 1 is shown below. Figure 9 As shown, its scanning electron microscope image is as follows: Figure 10 As shown.

[0079] Comparative Example 3

[0080] A method for processing aluminum alloys includes the following steps:

[0081] The aluminum alloy was subjected to solution treatment, quenching treatment and first-stage aging treatment in sequence.

[0082] The solution treatment includes the following steps: heating to 470℃ (solution treatment temperature) and holding at that temperature for 1 hour;

[0083] The quenching process includes the following steps: transferring the aluminum alloy that has undergone solution treatment to pure water (fluid) to cool to room temperature (the time from the completion of solution treatment to the completion of transfer should not exceed 10 seconds);

[0084] The first-level aging treatment includes the following steps: heating from room temperature to 120°C at 10°C / min and holding for 6 hours, then heating from 120°C to 180°C at 10°C / min and holding for 8 hours, and then transferring to pure water to cool to room temperature (the transfer time shall not exceed 10 seconds).

[0085] Comparative Example 4

[0086] A method for processing aluminum alloys includes the following steps:

[0087] The aluminum alloy was subjected to solution treatment, quenching treatment and first-stage aging treatment in sequence.

[0088] The solution treatment includes the following steps: heating to 470℃ (solution treatment temperature) and holding at that temperature for 1 hour;

[0089] The quenching process includes the following steps: transferring the aluminum alloy that has undergone solution treatment to pure water (fluid) to cool to room temperature (the time from the completion of solution treatment to the completion of transfer should not exceed 10 seconds);

[0090] The first-level aging treatment includes the following steps: heating from room temperature to 120°C at a rate of 10°C / min and holding at that temperature for 24 hours, then transferring to pure water to cool to room temperature (the transfer time should not exceed 10 seconds).

[0091] Comparative Example 5

[0092] Comparative Example 5 did not undergo any heat treatment on the aluminum alloy.

[0093] Morphological analysis

[0094] Reference Figure 6 The metallographic image of the aged aluminum alloy obtained by the treatment method in Comparative Example 1 shows that after the first-stage non-isothermal aging treatment, the grains of the aluminum alloy grow larger and the grain size is more uniform. (Refer to...) Figure 7 The scanning electron microscope (SEM) images of the aged aluminum alloy obtained by the treatment method of Comparative Example 1 show that after the first-stage non-isothermal aging treatment, the coarse precipitates observed under the SEM are almost all precipitated along the grain boundaries, appearing as discontinuous dots distributed at various grain boundaries. The precipitates observed in the matrix are primarily smaller precipitates. (Refer to...) Figure 8 Transmission electron microscopy (TEM) images of the grain boundaries of the aged aluminum alloy obtained by the aluminum alloy treatment method of Comparative Example 1 show that at this time, there are only a few coarse grain boundary precipitates, while most of them are still relatively fine precipitates, which are continuously distributed and form a narrow precipitation-free zone near the grain boundary, which is only 40.19 nm.

[0095] Reference Figure 9 The metallographic image of the aged aluminum alloy obtained by the treatment method of Comparative Example 2 shows that during the slow heating stage of the secondary aging treatment, static recrystallization occurred in the aluminum alloy. Fine grains nucleated and grew within the original grains, becoming interspersed between the original large grains. The average grain size decreased compared to Comparative Example 1, and the grain size was relatively less uniform. (Refer to...) Figure 10 The scanning electron microscope image of the aged aluminum alloy obtained by the aluminum alloy treatment method of Comparative Example 2 shows that, compared with Comparative Example 1, in the slow heating stage of the aluminum alloy after the second aging treatment, the dot-like grain boundary precipitates combine into chain-like strips and are dispersed at each grain boundary.

[0096] Reference Figure 3The metallographic image of the aged aluminum alloy obtained by the non-isothermal aging visible treatment method in Example 1 shows that after the rapid cooling stage of the second-stage non-isothermal aging treatment (i.e., complete second-stage aging), the aluminum alloy grains continue the static recrystallization process that was not completed in the previous stage during the rapid cooling process, while also avoiding excessive growth of the originally formed grains, resulting in a finer and more uniform grain structure compared to Comparative Examples 1 and 2. (Refer to...) Figure 4 The scanning electron microscope (SEM) images of the aged aluminum alloy obtained by the non-isothermal aging visible treatment method of Example 1 show that, compared to Comparative Examples 1 and 2, the density of precipitates in Example 1 is increased, and the chain-like, elongated, dot-like precipitates are more prevalent at various grain boundaries. (Refer to...) Figure 5 The transmission electron microscope (TEM) image of the matrix of the aged aluminum alloy obtained by the non-isothermal aging visible treatment method in Example 1 shows that the matrix precipitates of the aluminum alloy are fine and uniform, and diffusely distributed, with the main precipitated phase being the η' phase (Mg2Zn3). (Refer to...) Figure 6 The transmission electron microscope (TEM) image of the grain boundary of the aged aluminum alloy obtained by the non-isothermal aging visible treatment method of Example 1 shows that the coarse grain boundary precipitates are discontinuously distributed, and a relatively wide non-precipitate precipitate band of 62.37 nm is formed near the grain boundary.

[0097] Electrochemical corrosion performance test

[0098] Electrochemical corrosion performance tests were conducted on the aged aluminum alloys obtained in Example 1, Comparative Example 1, and Comparative Examples 3-5. The polarization curves are shown below. Figure 11 As shown, the self-corrosion potential and self-corrosion current density are obtained from the polarization curve fitting. Figure 12 As shown in Table 1.

[0099] Table 1 Results of Electrochemical Corrosion Performance Tests

[0100]

[0101] Referring to Table 1, it can be seen that the self-corrosion potential of Example 1 is -0.719V, and the self-corrosion current density is 2.2591×10⁻⁶. - 6 A / cm 2 Compared to Comparative Examples 1 and 3-5, its self-corrosion potential is more negative and its self-corrosion current density is smaller, proving that it has better corrosion resistance.

[0102] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method of non-isothermal ageing of an aluminium alloy, characterised in that, The method comprises the following steps: The aluminum alloy is sequentially subjected to solid solution treatment, quenching treatment, first non-isothermal aging treatment and second non-isothermal aging treatment; The first non-isothermal aging treatment comprises the following steps: heating to a first temperature at a first rate, then heating to a second temperature at a second rate, then cooling to the first temperature at the second rate, and finally cooling to room temperature at the first rate; The second non-isothermal aging treatment comprises the following steps: heating to a first temperature at a first rate, then heating to a second temperature at a second rate, and then cooling to room temperature at the second rate; If the aluminum alloy product obtained after the second non-isothermal aging treatment is in an incomplete aging state, then a third non-isothermal aging treatment is repeated until the aluminum alloy product reaches a complete aging state; the steps of the third non-isothermal aging treatment are the same as those of the first non-isothermal aging treatment; The aluminum alloy is an Al-Zn-Mg-Cu alloy; The first temperature is 110-130℃, the second temperature is 180-210℃, the first rate is 0.5-1℃ / min, and the second rate is 2-5℃ / min.

2. The aluminum alloy non-isothermal aging process of claim 1, wherein, The solid solution treatment comprises the following steps: heating to a solid solution treatment temperature and holding; The solid solution treatment temperature is 450-490℃, and the holding time is 1-2h.

3. The method of non-isothermal aging treatment of an aluminum alloy according to claim 1, characterized in that, The quenching treatment comprises the following steps: transferring the aluminum alloy after the solid solution treatment to a fluid to cool to room temperature; The fluid is water or an organic quenching liquid.

4. The aluminum alloy non-isothermal aging process of claim 3, wherein, The time from the completion of the solid solution treatment to the completion of the transferring is no more than 10s.

5. The method of non-isothermal aging treatment of an aluminum alloy of claim 1, wherein, The first non-isothermal aging treatment is an incomplete aging treatment.

6. Use of the aluminum alloy non-isothermal aging treatment method according to any one of claims 1-5 in the processing of an aluminum alloy.

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