A method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs

Abstract

The present invention provides a method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs; the method improves the toughness of aluminum alloy thin plates and reduces the manufacturing cost of aluminum alloy thin plates by controlling the coupling effect of a rolling treatment process and a solution treatment process; specifically, the method improves the toughness of aluminum alloy thin plates and significantly reduces the manufacturing cost of aluminum alloy thin plates by adjusting the rolling treatment process and the solution treatment process to control the grain characteristics, the area percentage of a coarse second phase and the texture ratio.

Description

Technical Field

[0001] The invention belongs to the technical field of cold deformation and heat treatment of hard aluminum alloys, and in particular relates to a method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs. Background Art

[0002] With the development of material technology, aircraft design has shifted from the earlier static strength requirements to damage tolerance requirements. Among them, toughness is an important evaluation item in the material damage tolerance performance. It can reflect the ability of organizational crack propagation and is a quantitative indicator of the material toughness. Aluminum alloy sheet materials are usually measured using plane stress fracture toughness. K C Apparent fracture toughness K app Value is evaluated.

[0003] Aluminum alloy sheet materials are usually prepared through the process of "melting → homogenization → machining → hot rolling (rough rolling, finishing rolling) → cold rolling (intermediate return) → solution quenching → leveling (stretching) → aging". This process has the disadvantages of long process, high preparation cost, many factors affecting performance, and strong coupling effect. At the same time, there is no clear way to improve the performance of aluminum alloy sheet materials. K C and K app The organizational characteristic structure and model of the value. In addition, the control methods for different series of aluminum alloy sheets such as 2000 and 7000 are also different. Therefore, it is very important to develop a method that can improve the toughness of aluminum alloy sheets in a short process and reduce the manufacturing cost. Summary of the invention

[0004] In order to improve the deficiencies of the prior art, the purpose of the present invention is to provide a method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs; the method is to achieve the improvement of the toughness of aluminum alloy thin plates and the reduction of manufacturing costs by regulating cold deformation and solid solution process.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A method for improving the toughness of an aluminum alloy sheet and reducing manufacturing costs, the method comprising the following steps:

[0007] 1) The alloy flat ingot is prepared by direct cooling semi-continuous casting method, and the rolled blank is obtained after homogenization heat treatment, machining and coating treatment;

[0008] 2) placing the rolled blank in step 1) in a heat preservation furnace for heat preservation treatment;

[0009] 3) first hot-rolling the rolled blank after heat preservation in step 2) to a thickness of δ1, and then cold-rolling to a thickness of δ2 to obtain an aluminum alloy plate; wherein the relationship between δ1 and δ2 satisfies (δ1-δ2) / δ1=50%~70%;

[0010] 4) The aluminum alloy plate of step 3) is subjected to solution quenching treatment, specifically: the furnace temperature is set to T℃, and the furnace temperature is linearly increased to T℃ again. The timing starts, and the solution heat preservation is completed and then the plate is taken out of the furnace for quenching. The quenching transfer time is ≤10s, and the quenching water temperature is 10~40℃; wherein, the time required from the completion of the temperature loading furnace to the linear increase of the furnace temperature to T℃ again is t1, and the solution heat preservation time is t2. The relationship between t1 and t2 satisfies 35min≤t1+t2≤55min, 4min≤t2≤6min; 476℃≤T≤499℃;

[0011] 5) Pre-stretch and level the aluminum alloy sheet within 1 hour after quenching, with a total stretching amount of 0.5~1.0%;

[0012] 6) Performing aging treatment on the pre-stretched and leveled aluminum alloy sheet to prepare the aluminum alloy thin plate.

[0013] According to an embodiment of the present invention, the aluminum alloy thin plate refers to an aluminum alloy plate with a thickness of ≤3.25 mm; exemplarily, the aluminum alloy thin plate refers to an aluminum alloy plate with a thickness of 1.6 mm to 3.25 mm, and further exemplarily, the thickness of the aluminum alloy thin plate is 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.2 mm, 2.5 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm or 3.25 mm.

[0014] According to an embodiment of the present invention, the method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs is to improve the toughness of aluminum alloy thin plates by controlling the rolling process and the solution treatment process, and to utilize the coupling effect of the two to reduce the manufacturing cost of aluminum alloy thin plates. Specifically, by controlling the cold deformation amount of the aluminum alloy sheet during the rolling process and the solution time and solution temperature during the solution process, the toughness of the aluminum alloy thin plates is improved and the manufacturing cost of the aluminum alloy thin plates is reduced through the coupling effect of the two.

[0015] According to the implementation mode of the present invention, the inventors of the present application found through research that the relationship between the thickness δ1 of the hot-rolled plate and the thickness δ2 of the cold-rolled plate satisfies (δ1-δ2) / δ1=50%~70%; at the same time, the temperature T of the solid solution is controlled to be 476℃~499℃ and the relationship between the time t1 of the heating section and the time t2 of the insulation section during the solid solution process satisfies t1+t2=35~55min, 4min≤t2≤6min; it can well realize the regulation of the alloy structure characteristics from three dimensions of coarse second phase, grain characteristics, and texture proportion, so as to improve the toughness of the aluminum alloy thin plate. By regulating the above parameters, the area percentage of coarse second phase in the alloy structure can be effectively reduced, thereby effectively reducing the formation of fracture sources; by regulating the above parameters, the grain characteristics (such as size, morphology and type) can also be effectively regulated, thereby significantly increasing the tortuosity of the fracture crack propagation path and reducing the risk of fracture; by regulating the above parameters, the texture proportion can also be effectively regulated, thereby increasing the difficulty of fracture crack tip propagation; in summary, the alloy structure characteristics can be regulated from three dimensions: coarse second phase, grain characteristics and texture proportion, thereby significantly improving the toughness of aluminum alloy thin plates.

[0016] According to an embodiment of the present invention, when the method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs is applied to 2000 series aluminum alloys, the average grain size in the obtained aluminum alloy thin plates is 19-24 μm, the aspect ratio is 2.5-3.5, more than 97% is in a completely recrystallized state, the area percentage of the coarse second phase is ≤2.2%, and the deformation texture and recrystallization texture account for 30-38% and 37-47% respectively, thereby improving the toughness of 2000 series aluminum alloy thin plates. K app Value up to 110MPa·m 1 / 2 Above the level.

[0017] According to an embodiment of the present invention, when the method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs is applied to 7000 series aluminum alloys, the average grain size in the obtained aluminum alloy thin plates is 28-32 μm, the aspect ratio is 5.0-6.0, more than 98% is in a completely recrystallized state, the area percentage of the coarse second phase is ≤1.1%, and the deformation texture and recrystallization texture account for approximately 20-25% and 50-55%, respectively, thereby improving the toughness of 7000 series aluminum alloy thin plates. K app Value up to 90MPa·m 1 / 2 Above the level.

[0018] According to an embodiment of the present invention, the method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs can also reduce the manufacturing cost of aluminum alloy thin plates. This is mainly because under traditional working conditions, the aluminum alloy plates are solution treated with reference to the solid solution temperature and insulation time mentioned in the "AMS 2772 G" standard. After research, the inventors of the present application unexpectedly found that when the solid solution temperature is increased, the solid solution insulation time is reduced, and the solid solution heating time is optimized at the same time, so that the Σ (heating + insulation) time in the solid solution process ≈ the traditional solid solution insulation time, while achieving the traditional solid solution treatment The dissolution effect on the precipitated phase is achieved, the energy consumption brought about by the heating stage in the traditional solid solution treatment process is greatly saved, which can significantly reduce the manufacturing cost of the aluminum alloy thin plate.

[0019] According to an embodiment of the present invention, in step 1), the process parameters involved in the direct cooling semi-continuous casting method (such as casting speed, casting water flow rate, etc.) are not particularly limited, and it can be a method known in the art that can prepare aluminum alloy flat ingots.

[0020] According to an embodiment of the present invention, in step 1), the alloy is a 2000 series aluminum alloy or a 7000 series aluminum alloy.

[0021] According to an embodiment of the present invention, the 2000 series aluminum alloy includes the following components in percentage by mass: Cu: 3.5~5.0%, Mg: 1.0~2.0%, Mn: 0.2~1.0%, Zn: 0.08~0.20%, Ti: 0.02~0.06%, Cr≤0.05%, Si≤0.12%, Fe≤0.12%, non-negligible impurity components≤0.1%, and Al balance.

[0022] According to an embodiment of the present invention, the 7000 series aluminum alloy includes the following components in percentage by mass: Cu: 1.0-2.0%, Mg: 2.0-3.0%, Zn: 5.0-6.0%, Ti: 0.02-0.06%, Cr: 0.15-0.25%, Mn≤0.1%, Si≤0.12%, Fe≤0.12%, non-negligible impurity components≤0.1%, and Al balance.

[0023] According to an embodiment of the present invention, in step 1), the size of the alloy flat ingot is not particularly limited, and can be reasonably selected according to the size requirements of the final aluminum alloy sheet. Exemplarily, the size of the alloy flat ingot is (200-500) mm×(1000-1600) mm (thickness×width).

[0024] According to an embodiment of the present invention, in step 1), the temperature of the homogenization heat treatment is 400°C~495°C; the time of the homogenization heat treatment is 36~60 hours. The homogenization heat treatment can be a single-stage homogenization treatment system, a two-stage homogenization heat treatment system, or a three-stage homogenization heat treatment system; illustratively, for 7000 series aluminum alloys, the homogenization heat treatment is, for example, 400°C×4~6h+470°C×2~4h+475°C×36~48h; for 2000 series aluminum alloys, the homogenization heat treatment is, for example, 490°C×36~48h; wherein, by selecting a suitable homogenization heat treatment system, a basis is provided for regulating the coarse second phase, grain characteristics and texture proportion of the alloy, which is beneficial to improving the toughness of aluminum alloy thin plates.

[0025] According to an embodiment of the present invention, in step 1), the present invention has no particular limitation on the equipment for the homogenization heat treatment, and any equipment for homogenization heat treatment well known to those skilled in the art can be used.

[0026] According to an embodiment of the present invention, in step 1), the process parameters involved in the machining are not particularly limited, and it can be a method known in the art that can transform an alloy slab ingot into a rolled blank; illustratively, the machining includes removing oxide scale on the surface of the alloy slab ingot.

[0027] According to an embodiment of the present invention, in step 1), the process parameters involved in the coating treatment are not particularly limited, and it is a method known in the art to coat the outer surface of a machined alloy flat ingot with an aluminum alloy layer. The coating treatment can better protect the surface of the aluminum alloy sheet and extend its service life; illustratively, the coating treatment is to coat the surface of the alloy flat ingot with a 1000 series aluminum alloy, and the thickness of the coating layer formed by the 1000 series aluminum alloy is not particularly defined as the thickness of the final aluminum alloy sheet, and can be specifically selected according to the composition of the aluminum alloy sheet and the composition of the 1000 series aluminum alloy and the application site of the aluminum alloy sheet. illustratively, the thickness of the coating layer formed by the 1000 series aluminum alloy accounts for 1-5% of the thickness of the final aluminum alloy sheet.

[0028] According to an embodiment of the present invention, in step 1), the size of the rolled blank is not particularly limited and can be reasonably selected according to the size requirements of the final aluminum alloy sheet.

[0029] According to an embodiment of the present invention, in step 2), the temperature of the heat preservation treatment is the initial rolling temperature of hot rolling. Exemplarily, the temperature of the heat preservation treatment is 430-440°C, for example, 430°C, 431°C, 432°C, 433°C, 434°C, 435°C, 436°C, 437°C, 438°C, 439°C or 440°C.

[0030] According to an embodiment of the present invention, in step 2), the time t of the heat preservation treatment and the thickness δ of the minimum cross section of the rolled blank satisfy t=δ×(0.9~1.2); wherein the unit of the time t is min, and the unit of the thickness δ is mm. This is conducive to keeping the temperature of the inner and outer surfaces of the rolled blank consistent. Exemplarily, when the thickness of the minimum cross section of the rolled blank is 400 mm, the time of the heat preservation treatment is 400×(0.9~1.2) min.

[0031] According to an embodiment of the present invention, in step 2), it is found that when the temperature of the insulation treatment is 430-440°C and the time t (in min) of the insulation treatment is 0.9-1.2 times the thickness (in mm) of the minimum cross-section of the rolled blank, it can ensure that the rolled blank is at a relatively high temperature and the temperatures of the inner and outer surfaces of the rolled blank are consistent, which is beneficial to the regulation of the alloy structure during hot rolling and cold rolling, especially to the reduction of the area percentage of the coarse second phase in the alloy structure during cold rolling, the regulation of grain characteristics (such as size, morphology and type) and the proportion of texture, which is beneficial to the improvement of the toughness of the aluminum alloy sheet.

[0032] According to an embodiment of the present invention, in step 3), the (δ1-δ2) / δ1 is 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%.

[0033] According to an embodiment of the present invention, in step 3), the unit of δ1 is mm, and the unit of δ2 is mm.

[0034] According to an embodiment of the present invention, in step 3), the initial rolling temperature of the hot rolling is 430-440°C; the final rolling temperature of the hot rolling is ≥380°C; the direction of the hot rolling is longitudinal rolling and / or alternating longitudinal and transverse rolling, the number of hot rolling passes is more than 10 passes, and the total deformation of the hot rolling is controlled to be ≥80%.

[0035] According to an embodiment of the present invention, in step 3), the cold rolling is performed by first air-cooling the hot-rolled aluminum alloy sheet to room temperature and then cold-rolling, that is, the cold rolling is performed at room temperature.

[0036] According to an embodiment of the present invention, in step 3), the cold rolling direction is longitudinal rolling, and the number of cold rolling passes is more than 10.

[0037] According to an embodiment of the present invention, in step 4), after the furnace temperature is linearly heated and reaches T°C, the door of the insulation furnace is opened, and the aluminum alloy plate to be solution quenched is placed in the insulation furnace. At this time, due to the opening of the furnace door, the temperature in the furnace will drop by more than 20°C; when all the aluminum alloy plates to be solution quenched are placed in the insulation furnace, the furnace door is closed, and the temperature in the furnace will be linearly heated to T°C again. When the temperature in the furnace is linearly heated to T°C again, the timing starts. After the solution insulation time is up, the aluminum alloy plate is taken out of the insulation furnace and quenched within 10 seconds; wherein, the time required from the closing of the furnace door to the linear heating of the furnace temperature to T°C again is t1, and t1 is the time required for the heating stage of the solution treatment; the residence time of the aluminum alloy plate at T°C is t2, and t2 is the time required for the insulation stage of the solution treatment.

[0038] According to an embodiment of the present invention, in step 4), the time required for the heating section (specifically, from the time when the furnace door is closed to the time when the temperature in the furnace is linearly heated to T°C again) that the aluminum alloy plate experiences during the solutionizing process is t1, and the time required for the insulation section (specifically, the residence time of the aluminum alloy plate in the insulation furnace after the temperature in the furnace is linearly heated to T°C again) that the aluminum alloy plate experiences during the solutionizing process is t2, and the relationship between t1 and t2 satisfies 35min≤t1+t2≤55min, 4min≤t2≤6min.

[0039] According to an embodiment of the present invention, in step 4), the t2 is 4 min, 4.5 min, 5 min, 5.5 min or 6 min.

[0040] According to an embodiment of the present invention, in step 4), the t1+t2 is 35min, 36min, 37min, 38min, 39min, 40min, 41min, 42min, 43min, 44min, 45min, 46min, 47min, 48min, 49min, 50min, 51min, 52min, 53min, 54min or 55min.

[0041] According to an embodiment of the present invention, in step 4), when the aluminum alloy is a 2000 series aluminum alloy, the solid solution temperature T is preferably 493-499° C. When the aluminum alloy is a 7000 series aluminum alloy, the solid solution temperature T is preferably 476-482° C.

[0042] According to an embodiment of the present invention, in step 5), the pre-stretching and leveling is performed by a method known in the art. The present invention does not impose any particular limitation on the specific method of pre-stretching and leveling, as long as the total stretching amount can be ensured to be 0.5-1.0%.

[0043] According to an embodiment of the present invention, in step 6), the aging treatment may be natural aging or artificial aging; illustratively, if the aluminum alloy is a 2000 series aluminum alloy, the aging treatment may be natural aging, such as placing at room temperature for 48 to 96 hours; if the aluminum alloy is a 7000 series aluminum alloy, the aging treatment may be artificial aging, such as keeping warm at 121 to 125°C for 24 to 48 hours.

[0044] Beneficial effects of the present invention:

[0045] The present invention provides a method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs; the method improves the toughness of aluminum alloy thin plates and reduces the manufacturing cost of aluminum alloy thin plates by controlling the coupling effect of a rolling treatment process and a solution treatment process; specifically, the method improves the toughness of aluminum alloy thin plates and significantly reduces the manufacturing cost of aluminum alloy thin plates by adjusting the rolling treatment process and the solution treatment process to control the grain characteristics, the area percentage of a coarse second phase and the texture ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the EBSD structure diagram of the aluminum alloy sheet of Example 1.

[0047] Figure 2 This is the EBSD microstructure diagram of the aluminum alloy sheet of Example 2.

[0048] Figure 3 This is the EBSD microstructure diagram of the aluminum alloy sheet of Example 3.

[0049] Figure 4 This is the EBSD microstructure diagram of the aluminum alloy sheet of Example 4.

[0050] Figure 5 This is the EBSD microstructure diagram of the aluminum alloy sheet of Example 5.

[0051] Figure 6 This is the EBSD microstructure diagram of the aluminum alloy sheet of Example 6.

[0052] Figure 7 This is the EBSD microstructure diagram of the aluminum alloy sheet of Comparative Example 1.

[0053] Figure 8 This is the EBSD structure diagram of the aluminum alloy sheet of Comparative Example 2.

[0054] Fig. 9 This is the EBSD microstructure diagram of the aluminum alloy sheet of Comparative Example 3.

[0055] Fig.10 This is the EBSD microstructure diagram of the aluminum alloy sheet of Comparative Example 4.

[0056] Fig.11 This is the EBSD microstructure diagram of the aluminum alloy sheet of Comparative Example 5.

[0057] Fig.12 This is the EBSD microstructure diagram of the aluminum alloy sheet of Comparative Example 6. DETAILED DESCRIPTION

[0058] The method of the present invention will be described in further detail below in conjunction with specific examples. It should be understood that the following examples are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0059] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0060] Example 1

[0061] The Al-4.5Cu-1.5Mg-0.6Mn-0.12Zn-0.04Ti alloy flat ingot was prepared by direct cooling semi-continuous casting method, and the alloy flat ingot was processed as follows to achieve the preparation of aluminum alloy thin plate.

[0062]

[0063] Example 2

[0064] The Al-4.5Cu-1.5Mg-0.6Mn-0.12Zn-0.04Ti alloy flat ingot was prepared by direct cooling semi-continuous casting method, and the alloy flat ingot was processed as follows to achieve the preparation of aluminum alloy thin plate.

[0065]

[0066] Example 3

[0067] The Al-4.5Cu-1.5Mg-0.6Mn-0.12Zn-0.04Ti alloy flat ingot was prepared by direct cooling semi-continuous casting method, and the alloy flat ingot was processed as follows to achieve the preparation of aluminum alloy thin plate.

[0068]

[0069] Example 4

[0070] The Al-5.5Zn-2.5Mg-1.5Cu-0.2Cr-0.04Ti alloy flat ingot was prepared by direct cooling semi-continuous casting method, and the alloy flat ingot was processed as follows to realize the preparation of aluminum alloy thin plate.

[0071]

[0072] Example 5

[0073] The Al-5.5Zn-2.5Mg-1.5Cu-0.2Cr-0.04Ti alloy flat ingot was prepared by direct cooling semi-continuous casting method, and the alloy flat ingot was processed as follows to realize the preparation of aluminum alloy thin plate.

[0074]

[0075] Example 6

[0076] The Al-5.5Zn-2.5Mg-1.5Cu-0.2Cr-0.04Ti alloy flat ingot was prepared by direct cooling semi-continuous casting method, and the alloy flat ingot was processed as follows to realize the preparation of aluminum alloy thin plate.

[0077]

[0078] Comparative Example 1

[0079] The other operations are the same as those in Example 3, except that the aluminum alloy plate is first hot rolled to a thickness of 12.5 mm, and then cold rolled to a thickness of 2.5 mm, that is, δ1 is 12.5 mm, δ2 is 2.5 mm, and the relationship between δ1 and δ2 is: (δ1-δ2) / δ1=80%.

[0080] Comparative Example 2

[0081] The other operations are the same as those in Example 3, except that the aluminum alloy plate is first hot rolled to a thickness of 4.2 mm, and then cold rolled to a thickness of 2.5 mm, that is, δ1 is 4.5 mm, δ2 is 2.5 mm, and the relationship between δ1 and δ2 is: (δ1-δ2) / δ1=40.5%.

[0082] Comparative Example 3

[0083] Other operations are the same as those in Example 5, except that:

[0084] The furnace temperature is set at 466±3℃, and the furnace is loaded at a temperature. After 49min (t1), the temperature is linearly increased to 466℃ and the insulation time is started. The insulation time is 6min (t2). The furnace is taken out of the furnace for quenching, the transfer time is 8s, and the water temperature is 25℃. The relationship with t2 is: t1+t2=55min.

[0085] Comparative Example 4

[0086] Other operations are the same as those in Example 5, except that:

[0087] The furnace temperature is set at 466±3℃, the furnace is loaded at temperature, and the temperature is linearly increased to 466℃ for 31min (t1), then the insulation time starts, the insulation time is 55min (t2), the furnace is taken out of the furnace for quenching, the transfer time is 8s, and the water temperature is 25℃; the relationship with t2 is: t1+t2=86min.

[0088] Comparative Example 5

[0089] Other operations are the same as those in Example 5, except that:

[0090] The furnace temperature is set at 479±3℃, and the furnace is loaded at a temperature. The temperature is linearly increased to 476℃ in 31min (t1), and then the insulation time is started. The insulation time is 55min (t2). The furnace is taken out of the furnace for quenching, the transfer time is 8s, and the water temperature is 25℃. The relationship with t2 is: t1+t2=86min.

[0091] Comparative Example 6

[0092] Other operations are the same as those in Example 5, except that:

[0093] The furnace temperature is set at 479±3℃, and the furnace is loaded at a temperature. The temperature is linearly increased to 476℃ in 5min (t1), and then the insulation time is started. The insulation time is 5min (t2). The furnace is taken out of the furnace for quenching, the transfer time is 8s, and the water temperature is 25℃. The relationship with t2 is: t1+t2=10min.

[0094] The performance test results of the aluminum alloy plates obtained in the above embodiments and comparative examples are shown in Table 1 and Table 2. Table 1 shows the performance evaluation and cost analysis results, and Table 2 shows the organization quantitative analysis results.

[0095] It can be seen from Tables 1 and 2 that the toughness of aluminum alloy sheets can be effectively improved by comprehensive regulation of the grain characteristics, aspect ratio, area percentage of coarse second phase, degree of recrystallization, and proportion of typical texture of aluminum alloy sheets; at the same time, the preparation cost of aluminum alloy sheets can be significantly reduced by optimizing the design of solid solution insulation.

[0096] Table 1 Performance evaluation and cost analysis

[0097]

[0098] Table 2 Quantitative characterization of tissues

[0099]

[0100] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs, wherein: The method comprises the following steps: 1) The alloy flat ingot is prepared by direct cooling semi-continuous casting method, and the rolled blank is obtained after homogenization heat treatment, machining and coating treatment; 2) placing the rolled blank in step 1) in a heat preservation furnace for heat preservation treatment; 3) first hot-rolling the rolled blank after heat preservation in step 2) to a thickness of δ1, and then cold-rolling to a thickness of δ2 to obtain an aluminum alloy plate; wherein the relationship between δ1 and δ2 satisfies (δ1-δ2) / δ1=50%~70%; 4) The aluminum alloy plate of step 3) is subjected to solution quenching treatment, specifically: the furnace temperature is set to T℃, and the furnace temperature is linearly increased to T℃ again. The timing starts, and the solution heat preservation is completed and then the plate is taken out of the furnace for quenching. The quenching transfer time is ≤10s, and the quenching water temperature is 10~40℃; wherein, the time required from the completion of the temperature loading furnace to the linear increase of the furnace temperature to T℃ again is t1, and the solution heat preservation time is t2. The relationship between t1 and t2 satisfies 35min≤t1+t2≤55min, 4min≤t2≤6min; 476℃≤T≤499℃; 5) Pre-stretch and level the aluminum alloy sheet within 1 hour after quenching, with a total stretching amount of 0.5~1.0%; 6) performing aging treatment on the pre-stretched and leveled aluminum alloy sheet to prepare the aluminum alloy thin plate; The aluminum alloy sheet refers to an aluminum alloy sheet with a thickness of ≤3.25 mm; In step 3), the initial rolling temperature of the hot rolling is 430-440°C; and the final rolling temperature of the hot rolling is ≥380°C.

2. The method for improving the toughness of aluminum alloy sheet and reducing the manufacturing cost according to claim 1, wherein: The aluminum alloy thin plate refers to an aluminum alloy plate with a thickness of 1.6 mm to 3.25 mm.

3. The method for improving the toughness of aluminum alloy sheet and reducing manufacturing cost according to claim 1, wherein: In step 1), the alloy is a 2000 series aluminum alloy or a 7000 series aluminum alloy; The 2000 series aluminum alloy includes the following components in percentage by mass: Cu: 3.5-5.0%, Mg: 1.0-2.0%, Mn: 0.2-1.0%, Zn: 0.08-0.20%, Ti: 0.02-0.06%, Cr≤0.05%, Si≤0.12%, Fe≤0.12%, non-negligible impurity components≤0.1%, and Al balance; The 7000 series aluminum alloy includes the following components in percentage by mass: Cu: 1.0-2.0%, Mg: 2.0-3.0%, Zn: 5.0-6.0%, Ti: 0.02-0.06%, Cr: 0.15-0.25%, Mn≤0.1%, Si≤0.12%, Fe≤0.12%, non-negligible impurity components≤0.1%, and Al balance.

4. The method for improving the toughness of aluminum alloy sheet and reducing the manufacturing cost according to claim 3, wherein: In step 1), for 2000 series aluminum alloy, the homogenization heat treatment is 490°C×36~48h; for 7000 series aluminum alloy, the homogenization heat treatment is 400°C×4~6h+470°C×2~4h+475°C×36~48h.

5. The method for improving the toughness of aluminum alloy sheet and reducing the manufacturing cost according to claim 1, wherein: In step 2), the temperature of the heat preservation treatment is the initial rolling temperature of hot rolling; In step 2), the time t of the heat preservation treatment and the thickness δ of the minimum cross section of the rolled blank satisfy t=δ×(0.9~1.2); wherein the unit of the time t is min, and the unit of the thickness δ is mm.

6. The method for improving the toughness of aluminum alloy sheet and reducing the manufacturing cost according to claim 1, wherein: In step 3), the hot rolling direction is longitudinal rolling and / or longitudinal and transverse alternating rolling, the number of hot rolling passes is more than 10, and the total deformation of hot rolling is controlled to be ≥80%; In step 3), the cold rolling direction is longitudinal rolling, and the number of cold rolling passes is more than 10.

7. The method for improving the toughness of aluminum alloy sheet and reducing the manufacturing cost according to claim 1, wherein: In step 4), when the aluminum alloy is a 2000 series aluminum alloy, the solid solution temperature T is 493-499°C; when the aluminum alloy is a 7000 series aluminum alloy, the solid solution temperature T is 476-482°C.

8. The method for improving the toughness of aluminum alloy sheet and reducing the manufacturing cost according to claim 1, wherein: In step 6), when the aluminum alloy is a 2000 series aluminum alloy, the aging treatment is natural aging, and the natural aging is placed at room temperature for 48 to 96 hours; when the aluminum alloy is a 7000 series aluminum alloy, the aging treatment is artificial aging, and the artificial aging is kept at 121 to 125° C. for 24 to 48 hours.

9. The method for improving the toughness of aluminum alloy sheet and reducing the manufacturing cost according to any one of claims 1 to 8, wherein: When the method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs is applied to 2000 series aluminum alloys, the average grain size in the obtained aluminum alloy thin plates is 19-24 μm, the aspect ratio is 2.5-3.5, more than 97% is in a completely recrystallized state, the area percentage of the coarse second phase is ≤2.2%, and the deformation texture and recrystallization texture account for 30-38% and 37-47% respectively, thereby improving the toughness of 2000 series aluminum alloy thin plates. K app Value up to 110MPa·m 1 / 2 above the level; When the method for improving the toughness of aluminum alloy thin plates and reducing manufacturing costs is applied to 7000 series aluminum alloys, the average grain size in the obtained aluminum alloy thin plates is 28-32 μm, the aspect ratio is 5.0-6.0, more than 98% is in a completely recrystallized state, the area percentage of the coarse second phase is ≤1.1%, and the deformation texture and recrystallization texture account for 20-25% and 50-55% respectively, thereby improving the toughness of 7000 series aluminum alloy thin plates. K app Value up to 90MPa·m 1 / 2 Above the level.

Images