Aluminum alloy sheet and preparation method thereof

Abstract

The present invention provides an aluminum alloy plate and a preparation method thereof. The preparation method comprises: step S1, smelting and casting the raw materials corresponding to the 7 series aluminum alloy in sequence to obtain a first ingot; step S2, performing homogenization heat treatment on the first ingot to obtain a second ingot; step S3, preheating and heat-insulating treatment on the second ingot to obtain an aluminum alloy ingot; step S4, hot rolling the aluminum alloy ingot to obtain a hot-rolled plate; step S5, cold rolling and / or solution treatment on the hot-rolled plate to obtain a plate; and step S6, performing finishing treatment and artificial aging on the plate in sequence to obtain an aluminum alloy plate. The aluminum alloy plate prepared by the above preparation method has good tensile properties and damage tolerance properties, and can be better applied to high-end manufacturing fields such as aviation, aerospace and automobiles.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an aluminum alloy plate and a preparation method thereof. Background Art

[0002] Aluminum alloys have the characteristics of low density, high specific strength, good toughness and corrosion resistance, and are widely used in aviation, aerospace, transportation, machinery, electronics, construction and other fields. 7xxx series alloys are typical representatives of high-strength and high-toughness deformable aluminum alloys, and have broad application prospects in aviation, aerospace, transportation and other fields. In order to improve the service performance and life of aerospace vehicles, it is necessary to further improve the tensile strength, fracture toughness, fatigue crack extension damage tolerance and other properties of 7xxx series alloy plates. However, the key performance levels of the existing 7xxx-T6 aluminum alloy plates and 7xxx-T7 aluminum alloy plates for aviation are insufficient and unstable. Therefore, it is urgent to develop an aluminum alloy plate with good tensile properties and damage tolerance. Summary of the invention

[0003] The main purpose of the present invention is to provide an aluminum alloy plate and a preparation method thereof, so as to solve the problem that the tensile properties and damage tolerance properties of 7xxx aluminum alloy plates in the prior art are poor.

[0004] In order to achieve the above-mentioned object, according to one aspect of the present invention, a method for preparing an aluminum alloy plate is provided, the method comprising: step S1, smelting and casting raw materials corresponding to the 7 series aluminum alloy in sequence to obtain a first ingot; step S2, performing homogenization heat treatment on the first ingot to obtain a second ingot; step S3, performing preheating and heat preservation treatment on the second ingot to obtain an aluminum alloy ingot; step S4, hot rolling the aluminum alloy ingot to obtain a hot-rolled plate; step S5, cold rolling and / or solution treatment on the hot-rolled plate to obtain a plate; and step S6, performing finishing treatment and artificial aging on the plate in sequence to obtain an aluminum alloy plate; wherein in step S2, the homogenization heat treatment process comprises heating the first ingot from 20-25°C to 465-489°C, and performing a first heat preservation and a first cooling in sequence to obtain a second ingot; in step S3, the preheating and heat preservation process comprises heating the second ingot from 20-25°C to 465-485°C, and performing a second heat preservation to obtain an aluminum alloy ingot.

[0005] Furthermore, the area fraction of the S phase in the aluminum alloy plate is 0.2-0.5%; preferably, the 7 series aluminum alloy is a 7 series Al-Zn-Mg-Cu aluminum alloy, and the 7 series Al-Zn-Mg-Cu aluminum alloy is selected from any one of AA7075 aluminum alloy, AA7475 aluminum alloy and AA7050 aluminum alloy.

[0006] Furthermore, in the above step S2, the heating rate of the homogenization heat treatment is 10 to 400°C / h, the first insulation time is 1 to 60h, and the first cooling is furnace cooling and / or air cooling; and / or, the second ingot is coated with aluminum and / or 7072 aluminum alloy and then preheated and insulated.

[0007] Furthermore, in the above step S3, the heating rate of the preheating and heat preservation treatment is 10 to 400°C / h, and the second heat preservation time is 1 to 20h.

[0008] Furthermore, in the above step S4, the starting temperature of the hot rolling treatment is 460-480°C, and the finishing temperature of the hot rolling treatment is 250-420°C; and / or, in the above step S5, the hot rolled plate is subjected to a second cooling after solution treatment, and the second cooling is selected from any one or more of water cooling, mist cooling and air cooling.

[0009] Furthermore, when a roller bottom quenching furnace or an air quenching furnace is used to perform the first solid solution treatment on the hot rolled plate, and the first solid solution treatment is a sheet solid solution treatment, the thickness of the aluminum alloy plate is ≥4.0 mm; wherein the temperature of the first solid solution treatment is 460-485°C, and the holding time of the first solid solution treatment is ≥1 min.

[0010] Furthermore, when a hot-rolled plate with a thickness of 4.0 to 12.0 mm is subjected to cold rolling and a second solution treatment in sequence, and the second solution treatment is a sheet solution treatment, the thickness of the aluminum alloy plate is 1.6 to 8.0 mm; wherein the cold rolling is a single cold rolling, and a first annealing treatment is performed before or after the single cold rolling, the temperature of the first annealing treatment is 300 to 400°C, and the holding time of the first annealing treatment is 1 to 15 hours; a roller bottom quenching furnace or an air quenching furnace is used for the second solution treatment, the temperature of the second solution treatment is 460 to 485°C, and the holding time of the second solution treatment is ≥1 minute.

[0011] Furthermore, when a hot-rolled plate with a thickness of 3.0 to 10.0 mm is subjected to cold rolling and a third solution treatment in sequence, and the third solution treatment is a coil solution treatment, the thickness of the aluminum alloy plate is 1.0 to 3.0 mm; wherein, the cold rolling is a single cold rolling, and a second annealing treatment is performed before or after the single cold rolling, the temperature of the second annealing treatment is 300 to 400°C, and the holding time of the second annealing treatment is 1 to 15 hours; an air cushion furnace is used for the third solution treatment, the temperature of the third solution treatment is 460 to 485°C, and the holding time of the third solution treatment is ≥1 min.

[0012] Furthermore, when a hot-rolled plate with a thickness of 3.0 to 6.0 mm is subjected to cold rolling and a fourth solution treatment in sequence, and the fourth solution treatment is a coil solution treatment, the thickness of the aluminum alloy plate is ≤1.0 mm; wherein, the cold rolling is a single cold rolling and a double cold rolling in sequence, the deformation of the single cold rolling is 10 to 65%, and the deformation of the double cold rolling is 35 to 70%; a third annealing treatment is performed before the single cold rolling or between the single cold rolling and the double cold rolling, the temperature of the third annealing treatment is 300 to 400°C, preferably 320 to 380°C; the holding time of the third annealing treatment is 1 to 15 hours, preferably 2 to 10 hours; an air cushion furnace is used for the fourth solution treatment, the temperature of the fourth solution treatment is 460 to 485°C, and the holding time of the fourth solution treatment is ≥1 min.

[0013] According to another aspect of the present invention, an aluminum alloy plate is provided. The aluminum alloy plate is prepared by the above-mentioned preparation method.

[0014] By applying the technical solution of the present invention, for the composition of the above-mentioned 7 series aluminum alloy raw materials and the content of Mg therein, the present application can effectively control the area fraction of the coarse second phase, namely the S phase, in the aluminum alloy ingot structure through the synergistic effect of the homogenization heat treatment and the preheating and heat preservation treatment process, thereby improving the tensile properties, fracture toughness and fatigue life of the aluminum alloy sheet. The above-mentioned 7 series aluminum alloy raw materials contain Zn elements, and the strength of the aluminum alloy can be further improved by solution treatment. At the same time, by solution treatment, the second phase precipitated in the preparation process is dissolved back, and the corresponding aging process is adopted, so that the production of aluminum alloy sheets in different states can be achieved, thereby meeting the comprehensive performance requirements of different fields. The hot rolling and cold rolling processes are used for preparation and molding, and the production of aluminum alloy sheets with different thickness specifications can be achieved. The aluminum alloy sheet prepared by the above preparation method has good tensile properties and damage tolerance performance, and can be better applied to high-end manufacturing fields such as aviation, aerospace and automobiles. DETAILED DESCRIPTION

[0015] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0016] As analyzed in the background technology of this application, the prior art has the problem that the tensile properties and damage tolerance performance of 7xxx aluminum alloy plates are poor. In order to solve the above problems, this application provides an aluminum alloy plate and a preparation method thereof.

[0017] In a typical embodiment of the present application, a method for preparing an aluminum alloy plate is provided, the preparation method comprising: step S1, smelting and casting raw materials corresponding to a 7 series aluminum alloy in sequence to obtain a first ingot; step S2, performing homogenization heat treatment on the first ingot to obtain a second ingot; step S3, performing preheating and heat preservation treatment on the second ingot to obtain an aluminum alloy ingot; step S4, hot rolling the aluminum alloy ingot to obtain a hot-rolled plate; step S5, cold rolling and / or solution treatment on the hot-rolled plate to obtain a plate; and step S6, performing finishing treatment and artificial aging on the plate in sequence to obtain an aluminum alloy plate; wherein in step S2, the homogenization heat treatment process comprises heating the first ingot from 20-25°C to 465-489°C, and performing a first heat preservation and a first cooling in sequence to obtain a second ingot; in step S3, the preheating and heat preservation process comprises heating the second ingot from 20-25°C to 465-485°C, and performing a second heat preservation to obtain an aluminum alloy ingot.

[0018] With respect to the composition of the above-mentioned 7 series aluminum alloy raw materials and the content of Mg therein, the present application can effectively control the area fraction of the coarse second phase, namely the S phase, in the aluminum alloy ingot structure through the synergistic effect of homogenization heat treatment and preheating and heat preservation treatment process, thereby improving the tensile properties, fracture toughness and fatigue life of the aluminum alloy sheet. The above-mentioned 7 series aluminum alloy raw materials contain Zn elements, and the strength of the aluminum alloy can be further improved by solution treatment. At the same time, by solution treatment, the second phase precipitated during the preparation process is dissolved back, and the corresponding aging process is adopted, so that the production of aluminum alloy sheets in different states can be achieved, thereby meeting the comprehensive performance requirements of different fields. The hot rolling and cold rolling processes are used for preparation and molding, and the production of aluminum alloy sheets of different thickness specifications can be achieved. The aluminum alloy sheet prepared by the above-mentioned preparation method has good tensile properties and damage tolerance performance, and can be better applied to high-end manufacturing fields such as aviation, aerospace and automobiles.

[0019] For the raw material of AA7075 aluminum alloy, when the aluminum alloy sheet with a thickness of 0.28-0.99 mm is obtained by the above preparation method, its transverse tensile strength is ≥490 MPa, transverse yield strength is ≥420 MPa, and transverse elongation is ≥8%. When the aluminum alloy sheet with a thickness of 0.99-1.57 mm is obtained, its transverse tensile strength is ≥496 MPa, transverse yield strength is ≥427 MPa, and transverse elongation is ≥9%. When the aluminum alloy sheet with a thickness of 1.57-4.75 mm is obtained, its transverse tensile strength is ≥510 MPa, transverse yield strength is ≥441 MPa, and transverse elongation is ≥9%. When the aluminum alloy sheet with a thickness of 4.75-6.32 mm is obtained, its transverse tensile strength is ≥524 MPa, transverse yield strength is ≥448 MPa, and transverse elongation is ≥9%.

[0020] For the raw material of AA7475 aluminum alloy, when the aluminum alloy sheet with a thickness of 6.35-12.67 mm is obtained by the above preparation method, its transverse tensile strength is ≥531 MPa, transverse yield strength is ≥476 MPa, transverse elongation is ≥10%, LT crack toughness K IC ≥33MPa*m 1 / 2 .

[0021] For the raw material of AA7050 aluminum alloy, when the aluminum alloy sheet with a thickness of 6.35-50.8 mm is obtained by the above preparation method, its transverse tensile strength is ≥510 MPa, transverse yield strength is ≥441 MPa, transverse elongation is ≥9%, LT crack toughness K IC ≥32MPa*m 1 / 2 , TL fatigue life (241MPa loading) ≥90000N.

[0022] In order to further improve the tensile properties, fracture toughness and fatigue life of the aluminum alloy plate, in one embodiment of the present application, the area fraction of the S phase in the aluminum alloy plate is 0.2-0.5%; preferably, the 7 series aluminum alloy is a 7 series Al-Zn-Mg-Cu aluminum alloy, and the 7 series Al-Zn-Mg-Cu aluminum alloy is selected from any one of AA7075 aluminum alloy, AA7475 aluminum alloy and AA7050 aluminum alloy.

[0023] The 7 series aluminum alloy is preferably a 7 series Al-Zn-Mg-Cu aluminum alloy, which helps to strengthen the interaction between the Cu element and the Mg element in the aluminum alloy, thereby helping to further control the content of the S phase, thereby improving the tensile properties, fracture toughness and fatigue life of the aluminum alloy sheet. The 7 series Al-Zn-Mg-Cu aluminum alloy includes but is not limited to the grades of the above aluminum alloys, such as AA7085, AA7136, AA7140, AA7049, AA7055, etc.

[0024] In one embodiment of the present application, in the above-mentioned step S2, the heating rate of the homogenization heat treatment is 10 to 400°C / h, the first insulation time is 1 to 60h, and the first cooling is furnace cooling and / or air cooling; and / or, the second ingot is coated with aluminum and / or 7072 aluminum alloy and then preheated and insulated.

[0025] It is preferred to control the heating rate of the homogenization heat treatment, the time of the first insulation and the cooling method of the first cooling within the above range, which is conducive to the second phase of the first ingot to dissolve back and reduce the precipitation of cooling, thereby reducing the content of the S phase in the alloy production process. It is preferred to use aluminum and / or 7072 aluminum alloy to coat the second ingot and perform preheating and insulation treatment, which is conducive to subsequent preheating and insulation treatment.

[0026] In one embodiment of the present application, in the above step S3, the heating rate of the preheating and heat preservation treatment is 10 to 400° C. / h, and the second heat preservation time is 1 to 20 hours.

[0027] It is preferred to control the heating rate of the preheating and heat-insulating treatment and the second heat-insulating time within the above range, which helps to dissolve the second phase of the second ingot, thereby reducing the content of the S phase during the alloy production process.

[0028] In one embodiment of the present application, in the above step S4, the starting temperature of the hot rolling treatment is 460-480°C, and the finishing temperature of the hot rolling treatment is 250-420°C; and / or, in the above step S5, the hot-rolled plate is subjected to a second cooling after a solid solution treatment, and the second cooling is selected from any one or more of water cooling, mist cooling and air cooling.

[0029] It is preferred to control the starting and finishing temperatures of the hot rolling process within the above ranges, which helps to control the grain size and uniformity of the alloy, thereby improving the strength and toughness of the aluminum alloy sheet. It is preferred to perform a second cooling after the hot rolled sheet is subjected to a solid solution treatment, and control the cooling method of the second cooling within the above ranges, which helps to control the precipitation of the second phase, thereby further improving the strength of the aluminum alloy sheet.

[0030] In one embodiment of the present application, when a roller bottom quenching furnace or an air quenching furnace is used to perform the first solid solution treatment on the hot-rolled plate, and the first solid solution treatment is a sheet solid solution treatment, the thickness of the aluminum alloy plate is ≥4.0 mm; wherein the temperature of the first solid solution treatment is 460-485°C, and the holding time of the first solid solution treatment is ≥1 min.

[0031] It is preferred that the hot-rolled plate that has been hot-rolled to the finished thickness is directly subjected to the above-mentioned first solution treatment, which helps to better obtain thick plate aluminum alloy products, that is, the thickness of the finished aluminum alloy plate is ≥4.0mm, preferably ≥6.0mm. It is preferred that the first solution treatment is a sheet solution treatment, and the temperature and holding time of the first solution treatment are preferably controlled within the above range, which helps to improve the strength and fracture toughness of the thick plate aluminum alloy plate. The sheet solution treatment production helps to further improve the uniformity of the heating temperature of the aluminum alloy plate, thereby reducing the holding time of the first solution heat treatment, and further improving the product consistency and production efficiency of the aluminum alloy plate.

[0032] In one embodiment of the present application, when a hot-rolled plate with a thickness of 4.0 to 12.0 mm is sequentially cold rolled and subjected to a second solution treatment, and the second solution treatment is a sheet solution treatment, the thickness of the aluminum alloy plate is 1.6 to 8.0 mm; wherein the cold rolling is a single cold rolling, and a first annealing treatment is performed before or after the single cold rolling, the temperature of the first annealing treatment is 300 to 400°C, and the holding time of the first annealing treatment is 1 to 15 hours; a roller bottom quenching furnace or an air quenching furnace is used for the second solution treatment, the temperature of the second solution treatment is 460 to 485°C, and the holding time of the second solution treatment is ≥1 minute.

[0033] It is preferred that the hot-rolled plate of the above thickness is subjected to a cold rolling and a second solution treatment in sequence, and it is further preferred that the thickness of the hot-rolled plate is 4.0 to 10.0 mm, which is helpful to better obtain a medium-thick plate aluminum alloy plate, that is, the thickness of the finished aluminum alloy plate is 1.6 to 8.0 mm, preferably 2.5 to 6.0 mm. It is preferred that the second solution treatment is a sheet solution treatment, and it is preferred to control the temperature and holding time of the second solution treatment within the above range, which is helpful to improve the strength and fracture toughness of the medium-thick plate aluminum alloy plate. Sheet solution production helps to further improve the uniformity of the heating temperature of the aluminum alloy plate, thereby reducing the holding time of the second solution heat treatment, and further improving the product consistency and production efficiency of the aluminum alloy plate. It is preferred to perform the first annealing treatment before or after the first cold rolling, and control the temperature and holding time of the first annealing treatment within the above range, which is helpful to refine the grains, thereby improving the plasticity and toughness of the aluminum alloy plate.

[0034] In one embodiment of the present application, when a hot-rolled plate with a thickness of 3.0 to 10.0 mm is sequentially cold rolled and subjected to a third solution treatment, and the third solution treatment is a coil solution treatment, the thickness of the aluminum alloy plate is 1.0 to 3.0 mm; wherein, the cold rolling is a single cold rolling, and a second annealing treatment is performed before or after the single cold rolling, the temperature of the second annealing treatment is 300 to 400°C, and the holding time of the second annealing treatment is 1 to 15 hours; an air cushion furnace is used for the third solution treatment, the temperature of the third solution treatment is 460 to 485°C, and the holding time of the third solution treatment is ≥1 min.

[0035] It is preferred that the hot-rolled plate of the above thickness is subjected to a cold rolling and a third solution treatment in sequence, and it is further preferred that the thickness of the hot-rolled plate is 5.0-8.0 mm, which is helpful to better obtain a thin plate aluminum alloy plate, that is, the thickness of the finished aluminum alloy plate is 1.0-3.0 mm, preferably 1.0-2.5 mm. It is preferred that the third solution treatment is a coil solution treatment, and it is preferred to control the temperature and holding time of the third solution treatment within the above range, which is helpful to improve the plasticity and elongation of the thin plate aluminum alloy plate. Coil solution treatment production is helpful to improve the heating continuity of the aluminum alloy plate, thereby reducing the auxiliary time of the third solution heat treatment, and further improving the product surface quality and production efficiency of the aluminum alloy plate. It is preferred that the second annealing treatment is performed before or after the first cold rolling, and the temperature and holding time of the second annealing treatment are controlled within the above range, which is helpful to refine the grains, thereby improving the plasticity and toughness of the aluminum alloy plate.

[0036] In one embodiment of the present application, when a hot-rolled plate with a thickness of 3.0 to 6.0 mm is subjected to cold rolling and a fourth solution treatment in sequence, and the fourth solution treatment is a coil solution treatment, the thickness of the aluminum alloy plate is ≤1.0 mm; wherein, the cold rolling is a first cold rolling and a second cold rolling in sequence, the deformation of the first cold rolling is 10 to 65%, and the deformation of the second cold rolling is 35 to 70%; a third annealing treatment is performed before the first cold rolling or between the first cold rolling and the second cold rolling, and the temperature of the third annealing treatment is 300 to 400°C, preferably 320 to 380°C; the holding time of the third annealing treatment is 1 to 15 hours, preferably 2 to 10 hours; an air cushion furnace is used for the fourth solution treatment, the temperature of the fourth solution treatment is 460 to 485°C, and the holding time of the fourth solution treatment is ≥1min.

[0037] It is preferred that the hot-rolled plate of the above thickness is subjected to a first cold rolling, a second cold rolling and a fourth solution treatment in sequence, and it is further preferred that the thickness of the hot-rolled plate is 4.0 to 6.0 mm, which is helpful to better obtain a thin plate aluminum alloy plate, that is, the thickness of the finished aluminum alloy plate is ≤1.0 mm, preferably ≤0.8 mm. It is preferred that the fourth solution treatment is a coil solution treatment, and it is preferred to control the temperature and holding time of the fourth solution treatment within the above range, which is helpful to improve the plasticity and elongation of the ultra-thin plate aluminum alloy plate. Coil solution treatment production is helpful to improve the heating continuity of the aluminum alloy plate, thereby reducing the auxiliary time of the fourth solution heat treatment, and further improving the product surface quality and production efficiency of the aluminum alloy plate. It is preferred that the third annealing treatment is performed before the first cold rolling or between the first cold rolling and the second cold rolling, and the temperature and holding time of the third annealing treatment are controlled within the above range, which is helpful to control the different size ranges of the grains, thereby improving the plasticity and toughness of the aluminum alloy plate.

[0038] In another typical embodiment of the present application, an aluminum alloy sheet is provided. The aluminum alloy sheet is prepared by the above-mentioned preparation method.

[0039] With respect to the composition of the above-mentioned 7-series aluminum alloy raw materials and the content of Cu and Mg therein, the present application can effectively control the area fraction of the coarse second phase, namely the S phase, in the aluminum alloy ingot structure through the joint application of homogenization heat treatment and preheating and heat preservation treatment process, thereby improving the tensile properties, fracture toughness and fatigue life of the aluminum alloy sheet. The aluminum alloy sheet prepared by the above-mentioned preparation method has excellent tensile properties, fracture toughness and fatigue life, and can be better applied to high-end manufacturing fields such as aviation, aerospace and automobiles.

[0040] Further, for the raw material of AA7075 aluminum alloy, when the aluminum alloy sheet with a thickness of 0.28 to 0.99 mm is obtained by the above preparation method, its transverse tensile strength is ≥490 MPa, transverse yield strength is ≥420 MPa, and transverse elongation is ≥8%. When the aluminum alloy sheet with a thickness of 0.99 to 1.57 mm is obtained, its transverse tensile strength is ≥496 MPa, transverse yield strength is ≥427 MPa, and transverse elongation is ≥9%. When the aluminum alloy sheet with a thickness of 1.57 to 4.75 mm is obtained, its transverse tensile strength is ≥510 MPa, transverse yield strength is ≥441 MPa, and transverse elongation is ≥9%. When the aluminum alloy sheet with a thickness of 4.75 to 6.32 mm is obtained, its transverse tensile strength is ≥524 MPa, transverse yield strength is ≥448 MPa, and transverse elongation is ≥9%.

[0041] For the raw material of AA7475 aluminum alloy, when the aluminum alloy sheet with a thickness of 6.35-12.67 mm is obtained by the above preparation method, its transverse tensile strength is ≥531 MPa, transverse yield strength is ≥476 MPa, transverse elongation is ≥10%, LT crack toughness K IC ≥33MPa*m 1 / 2 .

[0042] For the raw material of AA7050 aluminum alloy, when the aluminum alloy sheet with a thickness of 6.35-50.8 mm is obtained by the above preparation method, its transverse tensile strength is ≥510 MPa, transverse yield strength is ≥441 MPa, transverse elongation is ≥9%, LT crack toughness K IC ≥32MPa*m 1 / 2 , TL fatigue life (241MPa loading) ≥90000N.

[0043] It should be noted that due to the particularity of the alloy field and the limitations of existing testing and characterization methods, it is difficult to conduct a comprehensive quantitative characterization of the complex microstructure of the aluminum alloy plate obtained above, but experiments show that the aluminum alloy plate obtained in this application has higher tensile properties and damage tolerance performance.

[0044] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0045] Example 1

[0046] In terms of mass percentage, the AA7075 aluminum alloy raw material is prepared according to the following components: 5.60% Zn element, 2.50% Mg element, 1.60% Cu element, 0.23% Cr element, 0.10% Mn element, 0.03% Ti element, 0.15% Fe element and 0.05% Si element, and the remaining component is Al element, and then the raw material is melted and cast in sequence to obtain the first ingot. The first ingot is a flat ingot, and the cross-sectional size of the flat ingot is 1650 mm×520 mm.

[0047] The first ingot was subjected to homogenization heat treatment: the temperature was raised from 20°C to 485°C at a heating rate of 40°C / h, and a first heat preservation for 20h and a first air cooling were performed in sequence to obtain a second ingot, which was milled to a thickness of 480mm.

[0048] After the second ingot is coated with aluminum, it is preheated and kept warm: the temperature is raised from 20°C to 465°C at a heating rate of 40°C / h, and a second heat preservation is performed for 2h to obtain an aluminum alloy ingot.

[0049] The aluminum alloy ingot is hot rolled to obtain a hot rolled plate, wherein the starting thickness of the hot rolling process is 520 mm, the starting rolling temperature of the hot rolling process is 460° C., the hot rolling is performed to a finished product thickness of 6.0 mm, and the final rolling temperature of the hot rolling process is 300° C.

[0050] The hot rolled plate is subjected to a first solid solution treatment in a roller hearth quenching furnace and then subjected to a second cooling air cooling to obtain a plate, wherein the first solid solution treatment is a sheet solid solution treatment, the temperature of the first solid solution treatment is 475°C, and the holding time of the first solid solution treatment is 50 minutes.

[0051] The plate was subjected to finishing treatment and artificial aging at 121°C for 24 hours in sequence to obtain an aluminum alloy plate with a thickness of 6.0 mm.

[0052] Example 2

[0053] The difference from Example 1 is that the aluminum alloy ingot is hot rolled to 6.0 mm to obtain a hot rolled plate.

[0054] The hot-rolled plate is cold-rolled once to a finished product thickness of 3.0 mm, and then subjected to a second solid solution treatment in a roller bottom quenching furnace and then to a second cooling air cooling to obtain a plate. The second solid solution treatment is a sheet solid solution treatment, the second solid solution treatment temperature is 475°C, the second solid solution treatment holding time is 35 minutes, and finally an aluminum alloy plate with a thickness of 3.0 mm is obtained.

[0055] Example 3

[0056] The difference from Example 1 is that the aluminum alloy ingot is hot rolled to 6.0 mm to obtain a hot rolled plate.

[0057] The hot-rolled plate was cold-rolled once to a finished product thickness of 2.0 mm, and then a second annealing treatment was performed at 360°C, the holding time of the second annealing treatment was 4 hours, and then a third solid solution treatment was performed in an air cushion furnace, and then a second cooling air cooling was performed to obtain a plate. Among them, the third solid solution treatment was a coil solid solution treatment, the temperature of the third solid solution treatment was 475°C, and the holding time of the third solid solution treatment was 5 minutes, and finally an aluminum alloy plate with a thickness of 2.0 mm was obtained.

[0058] Example 4

[0059] The difference from Example 3 is that the hot-rolled plate with a thickness of 6.0 mm is cold-rolled once to a finished product thickness of 1.2 mm, and then a second annealing treatment is performed at 360°C, the holding time of the second annealing treatment is 4 hours, and a third solid solution treatment is performed in an air cushion furnace and then a second cooling air cooling is performed to obtain a plate. Among them, the third solid solution treatment is a coil solid solution treatment, the temperature of the third solid solution treatment is 475°C, and the holding time of the third solid solution treatment is 3 minutes, and finally an aluminum alloy plate with a thickness of 1.2 mm is obtained.

[0060] Example 5

[0061] The difference from Example 1 is that the aluminum alloy ingot is hot rolled to 4 mm to obtain a hot rolled plate.

[0062] After the hot-rolled plate is cold-rolled once to a thickness of 1.5 mm, a third annealing treatment is performed at 360°C, the holding time of the third annealing treatment is 4 hours, and then a second cold rolling is performed to a finished product thickness of 0.8 mm, and a fourth solid solution treatment is performed in an air cushion furnace and a second cooling air cooling is performed to obtain a plate. Among them, the fourth solid solution treatment is a coil solid solution treatment, the temperature of the fourth solid solution treatment is 475°C, the holding time of the fourth solid solution treatment is 2 minutes, the deformation of the first cold rolling is 63%, and the deformation of the second cold rolling is 47%, and finally an aluminum alloy plate with a thickness of 0.8 mm is obtained.

[0063] Example 6

[0064] The difference from Example 3 is that after the second ingot is coated with aluminum, a preheating and heat preservation treatment is performed: the temperature is raised from 20°C to 475°C at a heating rate of 40°C / h, and a second heat preservation is performed for 2h to obtain an aluminum alloy ingot, and finally an aluminum alloy plate with a thickness of 2.0 mm is obtained.

[0065] Example 7

[0066] The difference from Example 4 is that after the second ingot is coated with aluminum, a preheating and heat preservation treatment is performed: the temperature is increased from 20°C to 475°C at a heating rate of 40°C / h, and a second heat preservation is performed for 2h to obtain an aluminum alloy ingot, and finally an aluminum alloy plate with a thickness of 1.2mm is obtained.

[0067] Example 8

[0068] The difference from Example 5 is that after the second ingot is coated with aluminum, a preheating and heat preservation treatment is performed: the temperature is increased from 20°C to 475°C at a heating rate of 40°C / h, and a second heat preservation is performed for 2h to obtain an aluminum alloy ingot.

[0069] The aluminum alloy ingot is hot rolled to 4.0 mm to obtain a hot rolled plate.

[0070] After the hot-rolled sheet is cold-rolled once to a thickness of 1.8 mm, a third annealing treatment is performed at 360°C, the holding time of the third annealing treatment is 4 hours, and then a second cold rolling is performed to a finished product thickness of 1.0 mm, and a fourth solid solution treatment is performed in an air cushion furnace and a second cooling air cooling is performed to obtain a sheet. Among them, the deformation amount of the first cold rolling is 55%, and the deformation amount of the second cold rolling is 44%, and finally an aluminum alloy sheet with a thickness of 1.0 mm is obtained.

[0071] Example 9

[0072] The difference from Example 3 is that the first ingot is subjected to homogenization heat treatment: the temperature is increased from 20°C to 470°C at a heating rate of 40°C / h, and a first insulation for 30 hours and a first air cooling are performed in sequence to obtain a second ingot, and finally an aluminum alloy plate with a thickness of 2.0 mm is obtained.

[0073] Example 10

[0074] The difference from Example 1 is that, in terms of mass percentage, the AA7475 aluminum alloy raw material is prepared according to the following components: 5.70% Zn element, 2.25% Mg element, 1.60% Cu element, 0.21% Cr element, 0.03% Mn element, 0.03% Ti element, 0.05% Fe element and 0.05% Si element, with the remaining component being Al element, and then smelting and casting are performed in sequence to obtain the first ingot.

[0075] The aluminum alloy ingot is hot rolled to a finished product thickness of 7.0 mm to obtain a hot rolled plate, wherein the initial thickness of the hot rolling process is 480 mm, and the aluminum alloy plate with a thickness of 7.0 mm is finally obtained.

[0076] Embodiment 11

[0077] The difference from Example 1 is that, in terms of mass percentage, the AA7050 aluminum alloy raw material is prepared according to the following components: 6.20% Zn element, 2.25% Mg element, 2.30% Cu element, 0.12% Cr element, 0.05% Mn element, 0.03% Ti element, 0.05% Fe element and 0.05% Si element, with the remaining component being Al element, and then smelting and casting are performed in sequence to obtain the first ingot.

[0078] The aluminum alloy ingot is hot rolled to a finished product thickness of 40.0 mm to obtain a hot rolled plate, wherein the initial thickness of the hot rolling process is 480 mm.

[0079] The hot rolled plate is subjected to a first solid solution treatment in a roller hearth quenching furnace and then to a second cooling air cooling to obtain a plate, wherein the first solid solution treatment is a sheet solid solution treatment, the first solid solution treatment temperature is 475°C, and the first solid solution treatment holding time is 150 minutes.

[0080] The plate was subjected to finishing treatment and artificial aging at 163°C for 27 h in sequence to obtain an aluminum alloy plate with a thickness of 40.0 mm.

[0081] Example 12

[0082] The difference from Example 1 is that the area fraction of the S phase in the aluminum alloy plate is 0.5%.

[0083] Comparative Example 1

[0084] The difference from Example 3 is that after the second ingot is coated with aluminum, a preheating and heat preservation treatment is performed: the temperature is raised from 20°C to 440°C at a heating rate of 40°C / h, and a second heat preservation is performed for 8 hours to obtain an aluminum alloy ingot, and finally an aluminum alloy plate with a thickness of 2.0 mm is obtained.

[0085] Comparative Example 2

[0086] The difference from Example 4 is that after the second ingot is coated with aluminum, a preheating and heat preservation treatment is performed: the temperature is raised from 20°C to 440°C at a heating rate of 40°C / h, and a second heat preservation is performed for 8 hours to obtain an aluminum alloy ingot, and finally an aluminum alloy plate with a thickness of 1.2 mm is obtained.

[0087] Comparative Example 3

[0088] The difference from Example 3 is that the first ingot is subjected to homogenization heat treatment: the temperature is increased from 20°C to 455°C at a heating rate of 40°C / h, and a first insulation for 40 hours and a first air cooling are performed in sequence to obtain a second ingot, and finally an aluminum alloy plate with a thickness of 2.0 mm is obtained.

[0089] Comparative Example 4

[0090] The difference from Example 4 is that the first ingot is subjected to homogenization heat treatment: the temperature is increased from 20°C to 455°C at a heating rate of 40°C / h, and a first insulation for 40 hours and a first air cooling are performed in sequence to obtain a second ingot, and finally an aluminum alloy plate with a thickness of 1.2 mm is obtained.

[0091] Comparative Example 5

[0092] The difference from Comparative Example 1 is that the first ingot is subjected to homogenization heat treatment: the temperature is increased from 20°C to 455°C at a heating rate of 40°C / h, and a first insulation for 40 hours and a first air cooling are performed in sequence to obtain a second ingot, and finally an aluminum alloy plate with a thickness of 2.0 mm is obtained.

[0093] Comparative Example 6

[0094] The difference from Comparative Example 2 is that the first ingot is subjected to homogenization heat treatment: the temperature is increased from 20°C to 455°C at a heating rate of 40°C / h, and a first insulation for 40 hours and a first air cooling are performed in sequence to obtain a second ingot, and finally an aluminum alloy plate with a thickness of 1.2 mm is obtained.

[0095] Comparative Example 7

[0096] The difference from Example 10 is that the first ingot is subjected to homogenization heat treatment: the temperature is increased from 20°C to 455°C at a heating rate of 40°C / h, and a first heat preservation of 40h and a first cooling by air are performed in sequence to obtain a second ingot.

[0097] After the second ingot is coated with aluminum, it is preheated and kept warm: the temperature is raised from 20°C to 440°C at a heating rate of 40°C / h, and a second heat preservation is performed for 8 hours to obtain an aluminum alloy ingot, and finally an aluminum alloy sheet with a thickness of 7.0 mm is obtained.

[0098] Comparative Example 8

[0099] The difference from Example 11 is that the first ingot is subjected to homogenization heat treatment: the temperature is increased from 20°C to 455°C at a heating rate of 40°C / h, and a first heat preservation of 40h and a first cooling by air are performed in sequence to obtain a second ingot.

[0100] After the second ingot is coated with aluminum, it is preheated and kept warm: the temperature is raised from 20°C to 440°C at a heating rate of 40°C / h, and a second heat preservation is performed for 8 hours to obtain an aluminum alloy ingot, and finally an aluminum alloy plate with a thickness of 40.0 mm is obtained.

[0101] Test method:

[0102] Area fraction test of S phase: observation and statistics were performed by scanning electron microscopy (SEM).

[0103] Transverse tensile strength, transverse yield strength and transverse elongation test: tested according to GB / T 228.

[0104] LT fracture toughness test: tested according to GB / T 42914.

[0105] TL fatigue life test: tested according to GB / T 3075.

[0106] AMS performance: The test standard for AA7075 aluminum alloy is AMS4049N, the test standard for AA7475 aluminum alloy is AMS4090G, and the test standard for AA7050 aluminum alloy is AMS4050K.

[0107] The aluminum alloy plates of the above embodiments and comparative examples were subjected to performance tests, and the test results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0112] With respect to the composition of the above-mentioned 7 series aluminum alloy raw materials and the content of Mg therein, the present application can effectively control the area fraction of the coarse second phase, namely the S phase, in the aluminum alloy ingot structure through the synergistic effect of homogenization heat treatment and preheating and heat preservation treatment process, thereby improving the tensile properties, fracture toughness and fatigue life of the aluminum alloy sheet. The above-mentioned 7 series aluminum alloy raw materials contain Zn elements, and the strength of the aluminum alloy can be further improved by solution treatment. At the same time, by solution treatment, the second phase precipitated during the preparation process is dissolved back, and the corresponding aging process is adopted, so that the production of aluminum alloy sheets in different states can be achieved, thereby meeting the comprehensive performance requirements of different fields. The hot rolling and cold rolling processes are used for preparation and molding, and the production of aluminum alloy sheets of different thickness specifications can be achieved. The aluminum alloy sheet prepared by the above-mentioned preparation method has good tensile properties and damage tolerance performance, and can be better applied to high-end manufacturing fields such as aviation, aerospace and automobiles.

[0113] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. 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 preparing an aluminum alloy sheet, characterized in that: The preparation method comprises: Step S1, smelting and casting the raw materials corresponding to the 7 series aluminum alloy in sequence to obtain a first ingot; Step S2, subjecting the first ingot to homogenization heat treatment to obtain a second ingot; Step S3, preheating and heat-insulating the second ingot to obtain an aluminum alloy ingot; Step S4, hot rolling the aluminum alloy ingot to obtain a hot-rolled plate; Step S5, cold rolling and / or solution treatment of the hot-rolled sheet to obtain a sheet; and Step S6, performing finishing treatment and artificial aging on the plate in sequence to obtain the aluminum alloy plate; Wherein, in the step S2, the homogenization heat treatment process includes heating the first ingot from 20-25° C. to 465-489° C., and sequentially performing a first heat preservation and a first cooling to obtain the second ingot; In the step S3, the preheating and heat preservation process includes heating the second ingot from 20-25°C to 465-485°C and performing a second heat preservation to obtain the aluminum alloy ingot.

2. The preparation method according to claim 1, characterized in that: The area fraction of the S phase in the aluminum alloy plate is 0.2 to 0.5%; Preferably, the 7 series aluminum alloy is a 7 series Al-Zn-Mg-Cu aluminum alloy, and the 7 series Al-Zn-Mg-Cu aluminum alloy is selected from any one of AA7075 aluminum alloy, AA7475 aluminum alloy and AA7050 aluminum alloy.

3. The preparation method according to claim 1 or 2, characterized in that: In the step S2, the heating rate of the homogenization heat treatment is 10 to 400°C / h, the first insulation time is 1 to 60h, and the first cooling is furnace cooling and / or air cooling; and / or, the preheating and insulation treatment is performed after the second ingot is coated with aluminum and / or 7072 aluminum alloy.

4. The preparation method according to any one of claims 1 to 3, characterized in that In the step S3, the heating rate of the preheating and heat preservation treatment is 10 to 400°C / h, and the second heat preservation time is 1 to 20h.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step S4, the starting temperature of the hot rolling process is 460-480°C, and the final temperature of the hot rolling process is 250-420°C; And / or, in the step S5, the hot-rolled plate is subjected to a second cooling after the solution treatment, and the second cooling is selected from any one or more of water cooling, mist cooling and air cooling.

6. The preparation method according to any one of claims 1 to 5, characterized in that When a roller-bottom quenching furnace or an air quenching furnace is used to perform a first solid solution treatment on the hot-rolled plate, and the first solid solution treatment is a sheet solid solution treatment, the thickness of the aluminum alloy plate is ≥4.0 mm; The temperature of the first solution treatment is 460-485° C., and the holding time of the first solution treatment is ≥1 min.

7. The preparation method according to any one of claims 1 to 5, characterized in that When the hot-rolled plate having a thickness of 4.0 to 12.0 mm is subjected to the cold rolling and the second solid solution treatment in sequence, and the second solid solution treatment is a sheet solid solution treatment, the thickness of the aluminum alloy plate is 1.6 to 8.0 mm; Wherein, the cold rolling is a single cold rolling, and a first annealing treatment is performed before or after the single cold rolling, the temperature of the first annealing treatment is 300-400°C, and the holding time of the first annealing treatment is 1-15h; a roller bottom quenching furnace or an air quenching furnace is used for the second solid solution treatment, the temperature of the second solid solution treatment is 460-485°C, and the holding time of the second solid solution treatment is ≥1min.

8. The preparation method according to any one of claims 1 to 5, characterized in that When the hot-rolled plate with a thickness of 3.0 to 10.0 mm is subjected to the cold rolling and the third solution treatment in sequence, and the third solution treatment is coil solution treatment, the thickness of the aluminum alloy plate is 1.0 to 3.0 mm; Wherein, the cold rolling is a single cold rolling, and a second annealing treatment is performed before or after the single cold rolling, the temperature of the second annealing treatment is 300-400°C, and the holding time of the second annealing treatment is 1-15h; an air cushion furnace is used for the third solid solution treatment, the temperature of the third solid solution treatment is 460-485°C, and the holding time of the third solid solution treatment is ≥1min.

9. The preparation method according to any one of claims 1 to 5, characterized in that When the hot-rolled plate with a thickness of 3.0 to 6.0 mm is subjected to the cold rolling and the fourth solution treatment in sequence, and the fourth solution treatment is coil solution treatment, the thickness of the aluminum alloy plate is ≤1.0 mm; Wherein, the cold rolling is a first cold rolling and a second cold rolling in sequence, the deformation amount of the first cold rolling is 10-65%, and the deformation amount of the second cold rolling is 35-70%; A third annealing treatment is performed before the first cold rolling or between the first cold rolling and the second cold rolling, the temperature of the third annealing treatment is 300-400°C, preferably 320-380°C; the holding time of the third annealing treatment is 1-15h, preferably 2-10h; an air cushion furnace is used for the fourth solid solution treatment, the temperature of the fourth solid solution treatment is 460-485°C, and the holding time of the fourth solid solution treatment is ≥1min.

10. An aluminum alloy plate, characterized in that: The aluminum alloy sheet is prepared by the preparation method described in any one of claims 1 to 9.

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