Method for inhibiting natural aging of Al-Mg-Si-Cu alloy plate

Abstract

The invention provides a method for inhibiting natural aging of an Al-Mg-Si-Cu alloy plate, which comprises the following steps of: (1) preparing materials according to an alloy component range, and smelting and casting to obtain an aluminum alloy cast ingot; (2) the aluminum alloy cast ingot is subjected to homogenization treatment; (3) the homogenized aluminum alloy cast ingot is placed in a rolling mill to be subjected to hot rolling, and a hot-rolled plate is obtained; (4) the hot-rolled plate is placed in a rolling mill for cold rolling, and a cold-rolled plate is obtained; (5) the cold-rolled plate is subjected to solid solution quenching treatment in a salt bath furnace, the solid solution temperature ranges from 500 DEG C to 540 DEG C, the heat preservation time ranges from 1 s to 20 s, and the quenching mode is water quenching; and (6) the plate subjected to solid solution quenching is subjected to pre-aging treatment, the pre-aging temperature ranges from 70 DEG C to 120 DEG C, and the heat preservation time ranges from 7 h to 12 h. According to the method, solid solution quenching treatment and pre-aging are combined to regulate and control the solid solution degree of Mg and Si atoms dissolved into an aluminum matrix in the solid solution process and precipitation of Mg-Si-vacancy atomic clusters in the pre-aging process so as to inhibit natural aging of the Al-Mg-Si-Cu alloy plate.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy heat treatment, and in particular to a method for inhibiting natural aging of an Al-Mg-Si-Cu alloy plate. Background Art

[0002] With the continuous advancement of automobile lightweighting, medium-strength Al-Mg-Si-Cu alloys are widely used as automobile body panels. Al-Mg-Si-Cu alloys are heat-treatable aluminum alloys, and aging precipitation strengthening is their main strengthening method. The alloy is supplied in the T4 state (natural aging), has a low yield strength, and can provide good formability. In addition, Al-Mg-Si-Cu alloys can also be baked hardened with the help of subsequent coating and baking varnish processes, which significantly improves the strength of the alloy sheet and meets the use requirements of automobile body components.

[0003] After solution quenching, Al-Mg-Si-Cu alloy sheet has thermodynamic instability at room temperature. This thermodynamic instability is manifested by the so-called "natural aging" effect. The occurrence of natural aging will significantly reduce the forming ability and paint hardening ability of automobile body panels. Patent application with publication number CN117535601A discloses a composite deformation heat treatment method for inhibiting the natural aging of automobile aluminum alloy and improving the artificial aging response. The method performs pre-deformation, intermediate pre-aging, cold rolling, post-pre-deformation and final pre-aging on the cold-rolled aluminum alloy to achieve the purpose of inhibiting the formation of room temperature atomic clusters during the natural aging process; Patent application with publication number CN107740014A discloses a deep cryogenic treatment method for inhibiting the natural aging of aluminum alloy automobile sheet. The 6000 series aluminum alloy automobile sheet in the solution quenching state is first cooled to about -194°C with liquid nitrogen, and then stored in a liquid nitrogen thermostat at -80°C. The formation and conversion time of atomic clusters during the natural aging process are delayed by deep cryogenic treatment. The above two methods achieve the purpose of inhibiting the natural aging of the plate by adding a pre-deformation process and carrying out pre-aging in stages or creating a deep cryogenic treatment environment. However, adding pre-deformation and carrying out pre-aging treatment in stages increases the industrial production process and reduces production efficiency; and the low-temperature deep cryogenic treatment environment is difficult to achieve under industrial production conditions. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for inhibiting the natural aging of Al-Mg-Si-Cu alloy plates.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a method for inhibiting the natural aging of an Al-Mg-Si-Cu alloy plate, wherein the Al-Mg-Si-Cu alloy plate is subjected to solid solution quenching and pre-aging treatment;

[0007] The process parameters of solution quenching are: solution temperature is 500-540°C, holding time is 0-20s, and quenching method is water quenching;

[0008] The pre-aging process parameters are: pre-aging temperature is 70-120°C, and the holding time is 7-12h.

[0009] Preferably, a method for inhibiting natural aging of an Al-Mg-Si-Cu alloy sheet comprises the steps of:

[0010] (1) Melting and casting: mixing the aluminum alloy raw materials according to the composition range of the Al-Mg-Si-Cu alloy, placing the prepared aluminum alloy raw materials in a melting furnace to melt them into liquid aluminum alloy, and casting them into aluminum alloy ingots;

[0011] (2) homogenization treatment, homogenization treatment of the aluminum alloy ingot;

[0012] (3) hot rolling, placing the homogenized aluminum alloy ingot in a rolling mill for hot rolling to obtain a hot-rolled plate;

[0013] (4) cold rolling, placing the hot-rolled sheet in a rolling mill for cold rolling to obtain a cold-rolled sheet;

[0014] (5) Solution quenching: the cold-rolled sheet is solution quenched in a salt bath furnace at a solution temperature of 500 to 540°C, a holding time of 1 to 20 seconds, and a quenching method of water quenching;

[0015] (6) Pre-aging: The plate after solution quenching is subjected to pre-aging treatment, the pre-aging temperature is 70-120°C, and the holding time is 7-12h.

[0016] Furthermore, in step (1), the Al-Mg-Si-Cu alloy comprises the following alloy components in weight percentage:

[0017] Si 1.0%~1.4%, Fe 0.1~0.3%, Cu 0.05~0.2%, Mn 0.05%~0.10%, Mg0.4%~0.6%, Cr≤0.05%, Zn≤0.20%, Ti≤0.15%, and the balance is Al and unavoidable impurities.

[0018] Furthermore, the homogenization process in step (2) is as follows: the homogenization temperature is 540-560° C., the heat preservation time is 4-10 h, and the heating rate is 60-80° C. / h.

[0019] Furthermore, the hot rolling in step (3) includes hot rough rolling and hot finish rolling, wherein the hot rough rolling passes are 17 to 25 passes, the hot finish rolling passes are 5 passes, the thickness of the hot rolled intermediate billet obtained after hot rough rolling is 51 to 57 mm, the thickness of the hot rolled plate obtained after hot finish rolling is 8 to 10 mm, and the hot rolling coiling temperature is 300 to 360°C.

[0020] Furthermore, the cold rolling process in step (4) is a first cold rolling, an intermediate annealing, and a second cold rolling treatment; the intermediate annealing temperature is 400 to 450° C., and the holding time is 20 to 50 seconds.

[0021] Furthermore, in the step (4), the first cold rolling pass is distributed as follows: 8.0-10.0 mm→6.0-7.0 mm→4.0-5.0 mm; and the second cold rolling pass is distributed as follows: 2.0-3.0 mm→1.0-2.0 mm.

[0022] Furthermore, in the step (5), the quenching transfer time is 1 to 3 seconds.

[0023] Furthermore, in step (6), the pre-aging is carried out in a hot air circulation furnace, and during the pre-aging, the plates are evenly laid in the hot air circulation furnace and cannot be stacked.

[0024] The beneficial effects of the present invention are:

[0025] The present invention combines solution quenching treatment with pre-aging to regulate the degree of solid solution of Mg and Si atoms dissolved into an aluminum matrix during the solution process and the precipitation of Mg-Si-vacancy atomic clusters during the pre-aging process to inhibit the natural aging of the Al-Mg-Si-Cu alloy plate. In the process of solution quenching treatment, the present invention adopts a low solid solution temperature and a short heat preservation time to reduce the number of Mg and Si atoms dissolved into the aluminum matrix during the solution process. After the solution quenching, pre-aging is immediately performed, and the pre-aging temperature is high and the time is long, which promotes the formation of Mg-Si-vacancy atomic clusters in the matrix and reduces the formation of Mg-vacancy or Si-vacancy atomic clusters during the natural placement process, thereby inhibiting natural aging. Moreover, the method of the present invention can be implemented on an existing production line and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 It is a schematic diagram of the principle of inhibiting natural aging of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] The present invention provides a method for inhibiting natural aging of an Al-Mg-Si-Cu alloy plate, comprising the steps of:

[0030] (1) Melting and casting: mixing the aluminum alloy raw materials according to the composition range of the Al-Mg-Si-Cu alloy, placing the prepared aluminum alloy raw materials in a melting furnace to melt them into liquid aluminum alloy, and casting them into aluminum alloy ingots;

[0031] Specifically, the Al-Mg-Si-Cu alloy includes the following alloy components in weight percentage: Si 1.0% to 1.4%, Fe 0.1% to 0.3%, Cu 0.05% to 0.2%, Mn 0.05% to 0.10%, Mg 0.4% to 0.6%, Cr≤0.05%, Zn≤0.20%, Ti≤0.15%, the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.1%, and the content of a single type of impurity is ≤0.02%;

[0032] (2) homogenization treatment, homogenization treatment of the aluminum alloy ingot;

[0033] Specifically, the homogenization process is as follows: the homogenization temperature is 540-560°C, the holding time is 4-10h, and the heating rate is 60-80°C / h;

[0034] (3) hot rolling, placing the homogenized aluminum alloy ingot in a rolling mill for hot rolling to obtain a hot-rolled plate;

[0035] Specifically, the hot rolling includes hot rough rolling and hot finish rolling, wherein the hot rough rolling passes are 17 to 25, the hot finish rolling passes are 5, the thickness of the hot rolled intermediate billet after hot rough rolling is 51 to 57 mm, the thickness of the hot rolled plate after hot finish rolling is 8 to 10 mm, and the hot rolling coiling temperature is 300 to 360°C;

[0036] (4) cold rolling, placing the hot-rolled sheet in a rolling mill for cold rolling to obtain a cold-rolled sheet;

[0037] Specifically, the cold rolling process includes a first cold rolling, an intermediate annealing, and a second cold rolling process; wherein the first cold rolling pass is distributed as follows: 8.0-10.0 mm→6.0-7.0 mm→4.0-5.0 mm; the second cold rolling pass is distributed as follows: 2.0-3.0 mm→1.0-2.0 mm; the intermediate annealing temperature is 400-450° C., and the holding time is 20-50 s;

[0038] (5) Solution quenching: the cold-rolled sheet is solution quenched in a salt bath furnace at a solution temperature of 500-540°C and a holding time of 1-20 seconds. After solution holding, water quenching is performed, and the quenching transfer time is 1-3 seconds. Preferably, the solution temperature is 500-520°C and the holding time is 5-10 seconds.

[0039] (6) Pre-aging: transfer the plate after solution quenching to a hot air circulation furnace for pre-aging treatment, and the plate should be evenly laid in the hot air circulation furnace and should not be stacked. The pre-aging temperature is 70-120°C and the holding time is 7-12h.

[0040] Reference Figure 1 The present invention mainly suppresses the natural aging of Al-Mg-Si-Cu alloy sheet by regulating the degree of solid solution of Mg and Si atoms dissolved into the aluminum matrix during the solid solution process and the precipitation of Mg-Si-vacancy atomic clusters during the pre-aging process through the combination of solid solution quenching treatment and pre-aging. Among them, the present invention adopts a low solid solution temperature in the solid solution quenching process to reduce the number of Mg and Si atoms dissolved into the aluminum matrix during the solid solution process; after the solid solution quenching, pre-aging is immediately carried out, and the pre-aging temperature is high and the time is long, which promotes the formation of Mg-Si-vacancy atomic clusters in the matrix and reduces the formation of Mg-vacancy or Si-vacancy atomic clusters during the natural placement process, thereby playing a role in suppressing natural aging.

[0041] Example 1

[0042] This embodiment provides a method for preparing an Al-Mg-Si-Cu alloy plate, comprising the steps of:

[0043] (1) Melting and casting, determining the composition range of the Al-Mg-Si-Cu alloy: in terms of weight percentage, including Si 1.0%, Fe 0.15%, Cu 0.12%, Mn 0.06%, Mg 0.52%, Cr 0.02%, Zn 0.02%, Ti 0.01%, and the balance being Al and unavoidable impurities, and the total amount of impurities ≤ 0.1%, and the content of a single type of impurity ≤ 0.02%; mixing the ingredients according to the ratio, and using industrial pure aluminum, master alloy Al-Si, master alloy Al-Fe, master alloy Al-Mn, and master alloy Al-Cu as aluminum alloy raw materials, placing the prepared aluminum alloy raw materials in a melting furnace to melt into liquid aluminum alloy, and using a semi-continuous casting method of melting, stirring, slag skimming, degassing, deslagging, filtering, and casting to melt and cast the liquid aluminum alloy into aluminum alloy ingots;

[0044] (2) homogenization treatment: homogenization treatment is performed on the aluminum alloy ingot. The homogenization treatment process is as follows: homogenization temperature is 555°C, holding time is 8h, and heating rate is 70°C / h;

[0045] (3) hot rolling, placing the homogenized aluminum alloy ingot in a rolling mill for hot rough rolling and hot finish rolling to obtain a hot rolled plate; wherein the hot rough rolling is performed for 19 passes, and the thickness of the hot rolled intermediate billet after hot rough rolling is 57 mm; the hot finish rolling is performed by a rolling mill for five consecutive rollings to obtain a hot rolled plate with a thickness of 8 mm, and the hot rolling coiling temperature is 300-360°C;

[0046] (4) cold rolling, placing the hot-rolled plate on a rolling mill and cold rolling the plate in a rolling pass distribution of 8.0 → 6.7 mm → 4.8 mm → intermediate annealing → 2.5 mm → 1.5 mm to obtain a cold-rolled plate, with the intermediate annealing temperature being 420° C. and the holding time being 40 s;

[0047] (5) Solution quenching: the cold-rolled sheet is solution quenched in a salt bath furnace at a solution temperature of 500°C and a holding time of 3 seconds. After solution holding, water quenching is performed, and the quenching transfer time is 3 seconds.

[0048] (6) Pre-aging: The plates after solution quenching are immediately transferred to a hot air circulation furnace for pre-aging treatment. The plates are evenly laid in the hot air circulation furnace and cannot be stacked. The pre-aging temperature is set to 70°C and the holding time is 8h.

[0049] Example 2

[0050] This embodiment provides a method for preparing an Al-Mg-Si-Cu alloy plate, comprising the steps of:

[0051] (1) Melting and casting, determining the composition range of the Al-Mg-Si-Cu alloy: in terms of weight percentage, including Si 1.0%, Fe 0.15%, Cu 0.12%, Mn 0.06%, Mg 0.52%, Cr 0.02%, Zn 0.02%, Ti 0.01%, and the balance being Al and unavoidable impurities, and the total amount of impurities ≤ 0.1%, and the content of a single type of impurity ≤ 0.02%; mixing the ingredients according to the ratio, and using industrial pure aluminum, master alloy Al-Si, master alloy Al-Fe, master alloy Al-Mn, and master alloy Al-Cu as aluminum alloy raw materials, placing the prepared aluminum alloy raw materials in a melting furnace to melt into liquid aluminum alloy, and using a semi-continuous casting method of melting, stirring, slag skimming, degassing, deslagging, filtering, and casting to melt and cast the liquid aluminum alloy into aluminum alloy ingots;

[0052] (2) homogenization treatment: homogenization treatment is performed on the aluminum alloy ingot. The homogenization treatment process is as follows: homogenization temperature is 555°C, holding time is 8h, and heating rate is 70°C / h;

[0053] (3) hot rolling, placing the homogenized aluminum alloy ingot in a rolling mill for hot rough rolling and hot finish rolling to obtain a hot rolled plate; wherein the hot rough rolling is performed for 19 passes, and the thickness of the hot rolled intermediate billet after hot rough rolling is 57 mm; the hot finish rolling is performed by a rolling mill for five consecutive rollings to obtain a hot rolled plate with a thickness of 8 mm, and the hot rolling coiling temperature is 300-360°C;

[0054] (4) cold rolling, placing the hot-rolled plate on a rolling mill and cold rolling the plate in a rolling pass distribution of 8.0 → 6.7 mm → 4.8 mm → intermediate annealing → 2.5 mm → 1.5 mm to obtain a cold-rolled plate, with the intermediate annealing temperature being 420° C. and the holding time being 40 s;

[0055] (5) Solution quenching: the cold-rolled sheet is solution quenched in a salt bath furnace at a solution temperature of 500°C and a holding time of 5 seconds. After solution holding, water quenching is performed, and the quenching transfer time is 3 seconds.

[0056] (6) Pre-aging: The plates after solution quenching are immediately transferred to a hot air circulation furnace for pre-aging treatment. The plates are evenly laid in the hot air circulation furnace and cannot be stacked. The pre-aging temperature is set at 95°C and the holding time is 8h.

[0057] Example 3

[0058] This embodiment provides a method for preparing an Al-Mg-Si-Cu alloy plate, comprising the steps of:

[0059] (1) Melting and casting, determining the composition range of the Al-Mg-Si-Cu alloy: in terms of weight percentage, including Si 1.0%, Fe 0.15%, Cu 0.12%, Mn 0.06%, Mg 0.52%, Cr 0.02%, Zn 0.02%, Ti 0.01%, and the balance being Al and unavoidable impurities, and the total amount of impurities ≤ 0.1%, and the content of a single type of impurity ≤ 0.02%; mixing the ingredients according to the ratio, and using industrial pure aluminum, master alloy Al-Si, master alloy Al-Fe, master alloy Al-Mn, and master alloy Al-Cu as aluminum alloy raw materials, placing the prepared aluminum alloy raw materials in a melting furnace to melt into liquid aluminum alloy, and using a semi-continuous casting method of melting, stirring, slag skimming, degassing, deslagging, filtering, and casting to melt and cast the liquid aluminum alloy into aluminum alloy ingots;

[0060] (2) homogenization treatment: homogenization treatment is performed on the aluminum alloy ingot. The homogenization treatment process is as follows: homogenization temperature is 555°C, holding time is 8h, and heating rate is 70°C / h;

[0061] (3) hot rolling, placing the homogenized aluminum alloy ingot in a rolling mill for hot rough rolling and hot finish rolling to obtain a hot rolled plate; wherein the hot rough rolling is performed for 19 passes, and the thickness of the hot rolled intermediate billet after hot rough rolling is 57 mm; the hot finish rolling is performed by a rolling mill for five consecutive rollings to obtain a hot rolled plate with a thickness of 8 mm, and the hot rolling coiling temperature is 300-360°C;

[0062] (4) cold rolling, placing the hot-rolled plate on a rolling mill and cold rolling the plate in a rolling pass distribution of 8.0 → 6.7 mm → 4.8 mm → intermediate annealing → 2.5 mm → 1.5 mm to obtain a cold-rolled plate, with the intermediate annealing temperature being 420° C. and the holding time being 40 s;

[0063] (5) Solution quenching: the cold-rolled sheet is solution quenched in a salt bath furnace at a solution temperature of 520°C and a holding time of 7 seconds. After solution holding, water quenching is performed, and the quenching transfer time is 3 seconds.

[0064] (6) Pre-aging: The plates after solution quenching are immediately transferred to a hot air circulation furnace for pre-aging treatment. The plates are evenly laid in the hot air circulation furnace and cannot be stacked. The pre-aging temperature is set to 110°C and the holding time is 8h.

[0065] Example 4

[0066] This embodiment provides a method for preparing an Al-Mg-Si-Cu alloy plate, comprising the steps of:

[0067] (1) Melting and casting, determining the composition range of the Al-Mg-Si-Cu alloy: in terms of weight percentage, including Si 1.0%, Fe 0.15%, Cu 0.12%, Mn 0.06%, Mg 0.52%, Cr 0.02%, Zn 0.02%, Ti 0.01%, and the balance being Al and unavoidable impurities, and the total amount of impurities ≤ 0.1%, and the content of a single type of impurity ≤ 0.02%; mixing the ingredients according to the ratio, and using industrial pure aluminum, master alloy Al-Si, master alloy Al-Fe, master alloy Al-Mn, and master alloy Al-Cu as aluminum alloy raw materials, placing the prepared aluminum alloy raw materials in a melting furnace to melt into liquid aluminum alloy, and using a semi-continuous casting method of melting, stirring, slag skimming, degassing, deslagging, filtering, and casting to melt and cast the liquid aluminum alloy into aluminum alloy ingots;

[0068] (2) homogenization treatment: homogenization treatment is performed on the aluminum alloy ingot. The homogenization treatment process is as follows: homogenization temperature is 555°C, holding time is 8h, and heating rate is 70°C / h;

[0069] (3) hot rolling, placing the homogenized aluminum alloy ingot in a rolling mill for hot rough rolling and hot finish rolling to obtain a hot rolled plate; wherein the hot rough rolling is performed for 19 passes, and the thickness of the hot rolled intermediate billet after hot rough rolling is 57 mm; the hot finish rolling is performed by a rolling mill for five consecutive rollings to obtain a hot rolled plate with a thickness of 8 mm, and the hot rolling coiling temperature is 300-360°C;

[0070] (4) cold rolling, placing the hot-rolled plate on a rolling mill and cold rolling the plate in a rolling pass distribution of 8.0 → 6.7 mm → 4.8 mm → intermediate annealing → 2.5 mm → 1.5 mm to obtain a cold-rolled plate, with the intermediate annealing temperature being 420° C. and the holding time being 40 s;

[0071] (5) Solution quenching: the cold-rolled sheet is solution quenched in a salt bath furnace at a solution temperature of 540°C and a holding time of 10 seconds. After solution holding, water quenching is performed, and the quenching transfer time is 3 seconds.

[0072] (6) Pre-aging: the plates after solution quenching are immediately transferred to a hot air circulation furnace for pre-aging treatment. The plates are evenly laid in the hot air circulation furnace and cannot be stacked. The pre-aging temperature is set to 115°C and the holding time is 8h.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing an Al-Mg-Si-Cu alloy plate, which differs from Example 1 in that: in this comparative example, the solid solution temperature is 560°C, the holding time is 10s, water quenching is performed after solid solution holding, and the quenching transfer time is 3s; the pre-aging temperature is 60°C, and the holding time is 8h.

[0075] Comparative Example 2

[0076] This comparative example provides a method for preparing an Al-Mg-Si-Cu alloy plate, which differs from Example 1 in that: in this comparative example, the solid solution temperature is 500°C, the holding time is 5s, water quenching is performed after solid solution holding, and the quenching transfer time is 3s; the pre-aging temperature is 60°C, and the holding time is 8h.

[0077] Comparative Example 3

[0078] This comparative example provides a method for preparing an Al-Mg-Si-Cu alloy plate, which differs from Example 1 in that: in this comparative example, the solid solution temperature is 560°C, the holding time is 10s, water quenching is performed after solid solution holding, and the quenching transfer time is 3s; the pre-aging temperature is 95°C, and the holding time is 8h.

[0079] Comparative Example 4

[0080] This comparative example provides a method for preparing an Al-Mg-Si-Cu alloy plate, which differs from Example 1 in that: in this comparative example, the solid solution temperature is 500°C, the holding time is 5s, water quenching is performed after solid solution holding, and the quenching transfer time is 3s; the pre-aging temperature is 170°C, and the holding time is 8h.

[0081] The aluminum alloy plates prepared in the above Examples 1-4 and Comparative Examples 1-4 were placed at room temperature for 7 days, 30 days, 60 days, and 90 days, and were baked at 185°C*30 min. The mechanical properties of the aluminum alloy plates were tested by tensile testing using an INSTRON universal tensile testing machine in accordance with GB / T 228.1 standard. The yield strength test results before and after baking are shown in Tables 1 and 2 below, respectively.

[0082] Table 1 Yield strength test results of each embodiment and comparative example before baking

[0083]

[0084]

[0085] Table 2 Yield strength test results of each embodiment and comparative example after baking

[0086]

[0087] It can be seen from Tables 1 and 2 that after being stored at room temperature for 7, 30, 60 and 90 days, the mechanical properties of Examples 1-4 before baking increase very little, and have good room temperature stability, and have little effect on their baking mechanical properties, and the mechanical properties after baking remain basically unchanged with the extension of time; while after being stored at room temperature for 7, 30, 60 and 90 days, the mechanical properties of Comparative Examples 1-3 before baking increase greatly, and their mechanical properties are unstable at room temperature, and have a great impact on their baking mechanical properties, which will cause the mechanical properties after baking to gradually decrease with the extension of time; in addition, Comparative Example 4 uses a higher temperature for pre-aging, which can inhibit natural aging to a certain extent, but the inhibition effect is still not as good as that of Examples 1-4.

[0088] Although the present invention has been described in detail by reference to the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet, characterized in that: Solution quenching and pre-aging treatment of Al-Mg-Si-Cu alloy plates; The process parameters of solution quenching are: solution temperature is 500-540°C, holding time is 1-20s, and quenching method is water quenching; The pre-aging process parameters are: pre-aging temperature is 70-120°C, and the holding time is 7-12h.

2. A method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 1, characterized in that: (1) Melting and casting: mixing the aluminum alloy raw materials according to the composition range of the Al-Mg-Si-Cu alloy, placing the prepared aluminum alloy raw materials in a melting furnace to melt them into liquid aluminum alloy, and casting them into aluminum alloy ingots; (2) homogenization treatment, homogenization treatment of the aluminum alloy ingot; (3) hot rolling, placing the homogenized aluminum alloy ingot in a rolling mill for hot rolling to obtain a hot-rolled plate; (4) cold rolling, placing the hot-rolled sheet in a rolling mill for cold rolling to obtain a cold-rolled sheet; (5) Solution quenching: the cold-rolled sheet is solution quenched in a salt bath furnace at a solution temperature of 500 to 540°C, a holding time of 1 to 20 seconds, and a quenching method of water quenching; (6) Pre-aging: The plate after solution quenching is subjected to pre-aging treatment, the pre-aging temperature is 70-120°C, and the holding time is 7-12h.

3. The method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 1, characterized in that: The Al-Mg-Si-Cu alloy in step (1) comprises the following alloy components in weight percentage: Si 1.0%~1.4%, Fe 0.1~0.3%, Cu 0.05~0.2%, Mn 0.05%~0.10%, Mg 0.4%~0.6%, Cr≤0.05%, Zn≤0.20%, Ti≤0.15%, and the balance is Al and unavoidable impurities.

4. The method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 1, characterized in that: The homogenization process in step (2) is as follows: the homogenization temperature is 540-560° C., the heat preservation time is 4-10 hours, and the heating rate is 60-80° C. / h.

5. The method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 1, characterized in that: The hot rolling in step (3) includes hot rough rolling and hot finish rolling, wherein the hot rough rolling passes are 17 to 25 passes, the hot finish rolling passes are 5 passes, the thickness of the hot rolled intermediate billet obtained after hot rough rolling is 51 to 57 mm, the thickness of the hot rolled plate obtained after hot finish rolling is 8 to 10 mm, and the hot rolling coiling temperature is 300 to 360°C.

6. The method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 1, characterized in that: The cold rolling process in step (4) is a primary cold rolling, an intermediate annealing, and a secondary cold rolling treatment; the intermediate annealing temperature is 400 to 450° C., and the holding time is 20 to 50 seconds.

7. The method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 5, characterized in that: In the step (4), the first cold rolling pass distribution is: 8.0-10.0 mm→6.0-7.0 mm→4.0-5.0 mm; the second cold rolling pass distribution is: 2.0-3.0 mm→1.0-2.0 mm.

8. The method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 1, characterized in that: The quenching transfer time in step (5) is 1 to 3 seconds.

9. The method for inhibiting natural aging of Al-Mg-Si-Cu alloy sheet according to claim 1, characterized in that: In the step (6), the pre-aging is carried out in a hot air circulation furnace, and during the pre-aging, the plates are evenly laid in the hot air circulation furnace and cannot be stacked.

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