A 5-series aluminum alloy sheet strip containing a rare earth element y and a method of manufacturing the same

Abstract

The application provides a 5-series aluminum alloy plate strip containing rare earth element Y and a preparation method thereof. The aluminum alloy plate strip comprises the following components in percentage by mass: 0.05%<=Y<0.30%; 4.5%<Mg<=6.5%; 0.05<Fe<0.30%; 0.03<Si<0.20%; 0.01<Cr<0.30%; 0.01<Cu<0.25%; 0.01<Mn<0.30; 0.01<=Zn<0.40; 0.01<=Ti<=0.20%, and the balance of Al and inevitable impurities. The preparation steps of the aluminum alloy plate strip are as follows: smelting and semi-continuous casting, homogenization annealing, heating, hot rolling, cold rolling and finished product annealing. The aluminum alloy plate strip with a thickness of 0.1-0.5mm is prepared, the second phase and the grain size in the aluminum material are small, the grain orientation is random, the tensile strength is greater than or equal to 360MPa, the yield strength is greater than or equal to 260MPa, the elongation is greater than or equal to 10%, and the 180-degree bending does not crack. The technical requirements of 3C electronic products on the mechanical properties and bending properties of the aluminum alloy plate strip are met.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials, specifically relating to a 5-series aluminum alloy sheet and strip containing rare earth element Y and its preparation method. Background Technology

[0002] Aluminum alloys are widely used in various fields due to their low density, high strength, high plasticity, good thermal conductivity, and corrosion resistance. Especially in the field of 3C electronic products such as mobile phones and tablets, the application of aluminum and aluminum alloys is becoming increasingly common, showing a clear trend of replacing engineering plastics and enhancing the technological feel of products. 5-series aluminum alloys are Al-Mg series non-heat-treatable strengthening alloys, possessing numerous advantages such as high strength, good thermal conductivity, high dimensional stability, good formability and bending performance, and good anodizing performance. They are widely used in the frames, covers, and middle plates of mobile phones and tablets. At the same time, aluminum alloys are lighter than stainless steel and safer and more stable than other materials such as plastics and glass, with broad market prospects. The rapid updates and iterations of 3C electronic products make lightweighting one of their important development trends. While ensuring the appearance quality of 3C electronic products meets standards, higher requirements are placed on the tensile strength and formability of aluminum materials. Tensile strength ≥360MPa, yield strength ≥260MPa, elongation ≥12%, and no cracking after 180° bending.

[0003] Currently, mainstream 5-series aluminum alloy sheets and strips cannot meet the above technical requirements, and there is an urgent need to develop new 5-series aluminum alloy sheets and strips to meet the technical requirements of 3C products. Summary of the Invention

[0004] The purpose of this invention is to provide a 5-series aluminum alloy sheet and strip containing rare earth element Y and its preparation method. The obtained 5-series aluminum alloy sheet and strip has good tensile strength and formability, which can meet the performance requirements of 3C electronic products for materials.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing 5-series aluminum alloy sheet and strip containing rare earth element Y, comprising the following steps:

[0006] Step 1: Prepare the alloy composition according to the following mass percentages: 0.05%≤Y<0.30%; 4.5%<Mg≤6.5%; 0.05<Fe<0.30%; 0.03<Si<0.20%; 0.01<Cr<0.30%; 0.01<Cu<0.25%; 0.01<Mn<0.30; 0.01≤Zn<0.40; 0.01≤Ti≤0.20%, with the balance being Al and unavoidable impurities.

[0007] Step 2: The prepared alloy composition is smelted and semi-continuously cast. Y is added in the form of Al-Y binary alloy ingot. When adding Y, the Al-Y binary alloy ingot is added to the material frame, pressed into the melt, and stirred thoroughly.

[0008] Step 3: Perform a two-stage heat treatment on the prepared casting. The first stage heat treatment temperature is 400℃~450℃ and the holding time is 4~12h. The second stage heat treatment temperature is 470℃~520℃ and the holding time is 6~12h.

[0009] Step 4: Hot rolling, with an initial rolling temperature of 450~490℃ and a final rolling temperature of 320℃~360℃;

[0010] Step 5, cold rolling, with 8 to 15 cold rolling passes, a deformation rate of 10% to 30% per pass, and a total deformation rate of 70% to 98%. The intermediate annealing temperature during the cold rolling process is 280℃ to 330℃.

[0011] Step 6: Anneal the finished product at a temperature of 120~220℃.

[0012] Preferably, 0.05% ≤ Y < 0.25%.

[0013] Preferably, the melting temperature is 740~770℃, the refining stirring time is 20~30min, and the settling time in the melt furnace is 20~25min.

[0014] Preferably, the semi-continuous casting temperature is 700~720℃, the casting speed is 48~55mm / min, and the cooling water flow rate of the crystallizer is 138~159m³ / min. 3 / h.

[0015] Preferably, the thickness of the cold-rolled sheet is 0.1~0.5mm.

[0016] A 5-series aluminum alloy sheet and strip containing rare earth element Y, prepared by the above method, has the following composition by mass percentage: 0.05%≤Y<0.30%; 4.5%<Mg≤6.5%; 0.05<Fe<0.30%; 0.03<Si<0.20%; 0.01<Cr<0.30%; 0.01<Cu<0.25%; 0.01<Mn<0.30; 0.01≤Zn<0.40; 0.01≤Ti≤0.20%, with the balance being Al and unavoidable impurities; the aluminum alloy sheet and strip has a tensile strength ≥360MPa, a yield strength ≥260MPa, an elongation ≥10%, and does not crack when bent at 180°.

[0017] Analysis of the principle of this invention: Rare earth element Y can improve the fluidity of aluminum alloys and refine the alloy grains. When the amount of rare earth element Y added is 0.05 wt.%, the alloy has the best fluidity and the finest grain structure. Further increasing the amount of rare earth element Y reduces the degree of grain refinement, increases the amount of intergranular precipitates, reduces the improvement in the fluidity of the alloy molten metal, decreases the filling capacity, and reduces mechanical properties. This invention improves the fluidity of the melt by increasing the temperature during the smelting and casting processes, while simultaneously increasing the water volume to ensure sufficient cooling of the melt during the casting process, thereby effectively increasing the degree of grain refinement when Y > 0.05 wt.%.

[0018] The beneficial effects of this invention are: by adding the rare earth element Y, this invention promotes the fineness of the second phase and grain size in 5-series aluminum alloys. Compared with the second phase and grain size of conventional 5-series aluminum alloys, the aluminum material of this invention has a finer second phase size and a significantly increased quantity, a smaller average grain diameter, and random grain orientation.

[0019] This invention improves the strength of 5-series aluminum alloys by adding the rare earth element Y. Compared with the tensile strength of conventional 5-series aluminum alloys, the aluminum material in this invention has a higher tensile strength, increased by 10%.

[0020] This invention improves the formability of 5-series aluminum alloys by adding the rare earth element Y. Compared with the formability of conventional 5-series aluminum alloys, the aluminum material in this invention exhibits superior formability, exhibiting no cracking even after a 180° bend. Attached Figure Description

[0021] Figure 1 This is a second phase distribution diagram of the finished aluminum material described in Example 1 of the present invention;

[0022] Figure 2 This is a grain distribution diagram of the finished aluminum material described in Example 1 of the present invention;

[0023] Figure 3 This is a diagram of the deformation zone of the finished aluminum material after a 180° bend in Example 1 of the present invention;

[0024] Figure 4 This is a diagram showing the second phase distribution of the finished aluminum material in Comparative Example 1;

[0025] Figure 5 This is a grain distribution diagram of the finished aluminum material in Comparative Example 1;

[0026] Figure 6 This is a diagram of the deformation zone of the finished aluminum material after a 180° bend in Comparative Example 1. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the invention in any way.

[0028] Example 1: A 5-series aluminum alloy sheet / strip containing rare earth element Y has the following alloy composition: Y=0.10%; Mg=5.9%; Fe=0.25%; Si=0.08%; Cr=0.03%; Cu=0.02%; Mn=0.03%; Zn=0.01%; Ti=0.02%, with the balance being Al and unavoidable impurities. The preparation method includes the following steps:

[0029] (1) Melting and semi-continuous casting: Melting temperature 760℃, Al-Y binary alloy ingots and Mg ingots are added to the material frame and pressed into the melt and stirred to fully dissolve the intermediate alloy and achieve uniform distribution through stirring; the melt is refined and degassed by high-purity Ar gas powder injection refining method, and mechanical stirring is used for in-furnace stirring for 25 minutes. After removing the surface slag, it is allowed to stand for 25 minutes, and filtered by plate double-stage filtration and tubular filtration. Semi-continuous casting temperature 715℃, casting speed 55mm / min, and crystallizer cooling water flow rate 150m 3 / h;

[0030] (2) Homogenization treatment: First-stage homogenization temperature 440℃, holding time 8h; Second-stage homogenization temperature 520℃, holding time 8h.

[0031] (3) Hot rolling: initial rolling temperature 480℃, final rolling temperature 360℃;

[0032] (4) Cold rolling: The number of cold rolling passes is 8 to 15, the deformation rate of each pass is 10% to 30%, the total deformation rate is 70% to 98%, and the intermediate annealing temperature during the cold rolling process is 280 to 330℃;

[0033] (5) Finished product annealing: annealing temperature 150℃.

[0034] The aluminum alloy sheet and strip prepared by this composition and process has a thickness of 0.2 mm, a fine second phase size, an average grain diameter of 17 μm, random orientation, a tensile strength of 367 MPa, a yield strength of 270 MPa, an elongation of 12.0%, and does not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0035] Example 2: A 5-series aluminum alloy sheet / strip containing rare earth element Y has the following alloy composition: Y=0.22%; Mg=5.5%; Fe=0.15%; Si=0.06%; Cr=0.12%; Cu=0.05%; Mn=0.22%; Zn=0.03%; Ti=0.04%, with the balance being Al and unavoidable impurities. The preparation method includes the following steps:

[0036] (1) Melting and semi-continuous casting: Melting temperature 770℃, Al-Y binary alloy ingots and Mg ingots are added to the material frame and pressed into the melt for stirring. High-purity Ar gas is used for powder refining and degassing of the melt. Mechanical stirring is used for in-furnace stirring for 28 minutes. After removing the surface slag, it is allowed to stand for 23 minutes. Filtration is carried out using plate-type double-stage filtration and tubular filtration. Semi-continuous casting temperature 720℃, casting speed 48mm / min, and crystallizer cooling water flow rate 140m³ / min. 3 / h;

[0037] (2) Homogenization treatment: First-stage homogenization temperature 450℃, holding time 10h; Second-stage homogenization temperature 470℃, holding time 10h.

[0038] (3) Hot rolling: initial rolling temperature 470℃, final rolling temperature 340℃;

[0039] (4) Cold rolling: The number of cold rolling passes is 8 to 15, the deformation rate of each pass is 10% to 30%, the total deformation rate is 70% to 95%, and the intermediate annealing temperature during the cold rolling process is 330℃;

[0040] (5) Finished product annealing: annealing temperature 120℃.

[0041] The aluminum alloy sheet and strip prepared by this composition and process has a thickness of 0.1 mm, a fine second phase size, an average grain diameter of 17 μm, random orientation, a tensile strength of 372 MPa, a yield strength of 285 MPa, an elongation of 13.0%, and does not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0042] Example 3: A 5-series aluminum alloy sheet / strip containing rare earth element Y has the following alloy composition: Y=0.27%; Mg=4.6%; Fe=0.12%; Si=0.10%; Cr=0.15%; Cu=0.08%; Mn=0.25%; Zn=0.05%; Ti=0.06%, with the balance being Al and unavoidable impurities. The preparation method includes the following steps:

[0043] (1) Melting and semi-continuous casting: Melting temperature 765℃, Al-Y binary alloy ingots and Mg ingots are added to the material frame and pressed into the melt for stirring. High-purity Ar gas is used for powder refining and degassing of the melt. Mechanical stirring is used for in-furnace stirring for 23 minutes. After removing the surface slag, it is allowed to stand for 20 minutes. Filtration is carried out using plate-type double-stage filtration and tubular filtration. Semi-continuous casting temperature 700℃, casting speed 52mm / min, and crystallizer cooling water flow rate 140m³ / min. 3 / h;

[0044] (2) Homogenization treatment: First-stage homogenization temperature 400℃, holding time 12h; Second-stage homogenization temperature 500℃, holding time 12h.

[0045] (3) Hot rolling: initial rolling temperature 490℃, final rolling temperature 355℃;

[0046] (4) Cold rolling: The number of cold rolling passes is 8 to 15, the deformation rate of each pass is 10% to 30%, the total deformation rate is 70% to 95%, and the intermediate annealing temperature during the cold rolling process is 330℃;

[0047] (5) Finished product annealing: annealing temperature 220℃.

[0048] The aluminum alloy sheet and strip prepared by this composition and process have a thickness of 0.5 mm, a fine second phase size, an average grain diameter of 19 μm, random orientation, a tensile strength of 362 MPa, a yield strength of 263 MPa, an elongation of 13%, and do not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0049] Example 4: A 5-series aluminum alloy sheet / strip containing rare earth element Y has the following alloy composition: Y=0.08%; Mg=4.8%; Fe=0.1%; Si=0.12%; Cr=0.18%; Cu=0.1%; Mn=0.28%; Zn=0.1%; Ti=0.08%, with the balance being Al and unavoidable impurities. The preparation method includes the following steps:

[0050] (1) Melting and semi-continuous casting: Melting temperature 750℃, Al-Y binary alloy ingots and Mg ingots are added to the material frame and pressed into the melt for stirring. High-purity Ar gas is used for powder refining to degas the melt. Mechanical stirring is used for in-furnace stirring for 20 minutes. After removing the surface slag, it is allowed to stand for 25 minutes. Filtration is carried out using plate-type double-stage filtration and tubular filtration. Semi-continuous casting temperature 710℃, casting speed 53mm / min, and crystallizer cooling water flow rate 150m³ / min. 3 / h;

[0051] (2) Homogenization treatment: First-stage homogenization temperature 410℃, holding time 9h; Second-stage homogenization temperature 510℃, holding time 9h.

[0052] (3) Hot rolling: initial rolling temperature 485℃, final rolling temperature 350℃;

[0053] (4) Cold rolling: The number of cold rolling passes is 8 to 15, the deformation rate of each pass is 10% to 30%, the total deformation rate is 70% to 98%, and the intermediate annealing temperature during the cold rolling process is 300℃.

[0054] (5) Finished product annealing: annealing temperature 130℃.

[0055] The aluminum alloy sheet and strip prepared by this composition and process have a thickness of 0.2 mm, a fine second phase size, an average grain diameter of 18 μm, random orientation, a tensile strength of 369 MPa, a yield strength of 263 MPa, an elongation of 11%, and do not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0056] Example 5: A 5-series aluminum alloy sheet / strip containing rare earth element Y has the following alloy composition: Y=0.12%; Mg=5%; Fe=0.18%; Si=0.14%; Cr=0.2%; Cu=0.12%; Mn=0.05%; Zn=0.12%; Ti=0.1%, with the balance being Al and unavoidable impurities. The preparation method includes the following steps:

[0057] (1) Melting and semi-continuous casting: Melting temperature 740℃, Al-Y binary alloy ingots and Mg ingots are added to the material frame and pressed into the melt for stirring. High-purity Ar gas is used for powder refining and degassing of the melt. Mechanical stirring is used for in-furnace stirring for 30 min. After removing the surface slag, it is allowed to stand for 21 min. Filtration is carried out using plate-type double-stage filtration and tubular filtration. Semi-continuous casting temperature 705℃, casting speed 50 mm / min, and crystallizer cooling water flow rate 150 m³ / min. 3 / h;

[0058] (2) Homogenization treatment: First-stage homogenization temperature 405℃, holding time 4h; Second-stage homogenization temperature 480℃, holding time 6h.

[0059] (3) Hot rolling: initial rolling temperature 450℃, final rolling temperature 320℃;

[0060] (4) Cold rolling: The number of cold rolling passes is 8 to 15, the deformation rate of each pass is 10% to 30%, the total deformation rate is 75% to 98%, and the intermediate annealing temperature during the cold rolling process is 290℃;

[0061] (5) Finished product annealing: annealing temperature 140℃.

[0062] The aluminum alloy sheet and strip prepared by this composition and process has a thickness of 0.3 mm, a fine second phase size, an average grain diameter of 21 μm, random orientation, a tensile strength of 367 MPa, a yield strength of 267 MPa, an elongation of 12%, and does not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0063] Example 6: Based on Example 1, the alloy composition of the aluminum alloy sheet and strip is as follows: Y=0.15%; Mg=5.2%; Fe=0.2%; Si=0.17%; Cr=0.23%; Cu=0.15%; Mn=0.08%; Zn=0.16%; Ti=0.12%, with the balance being Al and unavoidable impurities.

[0064] In the preparation method, the melting temperature is 745℃, the stirring time is 21 min, and the settling time is 22 min; the semi-continuous casting temperature is 708℃, the casting speed is 52 mm / min, and the cooling water flow rate of the crystallizer is 159 m³ / min. 3 / h; First-stage homogenization temperature 415℃, holding for 6h; Second-stage homogenization temperature 475℃, holding for 7h; Hot rolling start temperature 460℃, finishing rolling temperature 330℃; Cold rolling passes 8~15, pass deformation rate 10%~30%, total deformation rate 70%~98%, intermediate annealing temperature 320℃ during cold rolling; Finished product annealing temperature 160℃.

[0065] The aluminum alloy sheet and strip prepared by this composition and process has a thickness of 0.5 mm, a fine second phase size, an average grain diameter of 17 μm, random orientation, a tensile strength of 371 MPa, a yield strength of 273 MPa, an elongation of 11%, and does not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0066] Example 7: Based on Example 1, the alloy composition of the aluminum alloy sheet and strip is as follows: Y=0.17%; Mg=5.5%; Fe=0.08%; Si=0.18%; Cr=0.25%; Cu=0.16%; Mn=0.1%; Zn=0.18%; Ti=0.14%, with the balance being Al and unavoidable impurities.

[0067] In the preparation method, the melting temperature is 755℃, the stirring time is 22 min, and the settling time is 23 min; the semi-continuous casting temperature is 703℃, the casting speed is 48 mm / min, and the cooling water flow rate of the crystallizer is 158 m³ / min. 3 / h; First-stage homogenization temperature 420℃, holding for 8h; Second-stage homogenization temperature 485℃, holding for 8h; Hot rolling start temperature 480℃, finishing rolling temperature 350℃; Cold rolling passes 8~15, pass deformation rate 10%~30%, total deformation rate 70%~98%, intermediate annealing temperature 310℃ during cold rolling; Finished product annealing temperature 170℃.

[0068] The aluminum alloy sheet and strip prepared by this composition and process has a thickness of 0.2 mm, a fine second phase size, an average grain diameter of 22 μm, random orientation, a tensile strength of 369 MPa, a yield strength of 272 MPa, an elongation of 13%, and does not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0069] Example 8: Based on Example 1, the alloy composition of the aluminum alloy sheet and strip is as follows: Y=0.2%; Mg=5.7%; Fe=0.25%; Si=0.05%; Cr=0.27%; Cu=0.18%; Mn=0.13%; Zn=0.23%; Ti=0.16%, with the balance being Al and unavoidable impurities.

[0070] In the preparation method, the melting temperature is 748℃, the stirring time is 24 min, and the settling time is 24 min; the semi-continuous casting temperature is 712℃, the casting speed is 50 mm / min, and the cooling water flow rate of the crystallizer is 150 m³ / min. 3 / h; First-stage homogenization temperature 425℃, holding for 10h; Second-stage homogenization temperature 490℃, holding for 10h; Hot rolling start temperature 455℃, finishing rolling temperature 325℃; Cold rolling passes 8~15, pass deformation rate 10%~30%, total deformation rate 70%~98%, intermediate annealing temperature 300℃ during cold rolling; Finished product annealing temperature 180℃.

[0071] The aluminum alloy sheet and strip prepared by this composition and process has a thickness of 0.4 mm, a fine second phase size, an average grain diameter of 20 μm, random orientation, a tensile strength of 370 MPa, a yield strength of 281 MPa, an elongation of 11%, and does not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0072] Example 9: Based on Example 1, the alloy composition of the aluminum alloy sheet and strip is as follows: Y=0.25%; Mg=6.1%; Fe=0.27%; Si=0.08%; Cr=0.05%; Cu=0.2%; Mn=0.15%; Zn=0.25%; Ti=0.18%, with the balance being Al and unavoidable impurities.

[0073] In the preparation method, the melting temperature is 758℃, the stirring time is 26 min, and the settling time is 26 min; the semi-continuous casting temperature is 718℃, the casting speed is 50 mm / min, and the cooling water flow rate of the crystallizer is 150 m³ / min. 3 / h; First-stage homogenization temperature 430℃, holding for 12h; Second-stage homogenization temperature 495℃, holding for 11h; Hot rolling start temperature 475℃, finishing rolling temperature 345℃; Cold rolling passes 8~15, pass deformation rate 10%~30%, total deformation rate 70%~95%; Intermediate annealing temperature during cold rolling 285℃; Finished product annealing temperature 190℃.

[0074] The aluminum alloy sheet and strip prepared by this composition and process has a thickness of 0.5 mm, a fine second phase size, an average grain diameter of 19 μm, random orientation, a tensile strength of 365 MPa, a yield strength of 265 MPa, an elongation of 12%, and does not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0075] Example 10: Based on Example 1, the alloy composition of the aluminum alloy sheet and strip is as follows: Y=0.28%; Mg=6.4%; Fe=0.21%; Si=0.05%; Cr=0.1%; Cu=0.23%; Mn=0.18%; Zn=0.35%; Ti=0.2%, with the balance being Al and unavoidable impurities.

[0076] In the preparation method, the melting temperature is 768℃, the stirring time is 27 min, and the settling time is 27 min; the semi-continuous casting temperature is 720℃, the casting speed is 51 mm / min, and the cooling water flow rate of the crystallizer is 155 m³ / min. 3 / h; First-stage homogenization temperature 435℃, holding for 5h; Second-stage homogenization temperature 515℃, holding for 9h; Hot rolling start temperature 465℃, finishing rolling temperature 335℃; Cold rolling passes 8~15, pass deformation rate 10%~30%, total deformation rate 70%~98%; Intermediate annealing temperature 280℃ during cold rolling; Finished product annealing temperature 200℃.

[0077] The aluminum alloy sheet and strip prepared using this composition and process have a thickness of 0.2 mm, a fine second phase size, an average grain diameter of 23 μm, random orientation, a tensile strength of 362 MPa, a yield strength of 264 MPa, an elongation of 13%, and do not crack when bent at 180°. It exhibits excellent tensile strength and formability, meeting the technical requirements of 3C products for aluminum materials.

[0078] Comparative Example 1: The alloy composition of Comparative Example 1 is the same as that of Example 1. The preparation method includes the following steps:

[0079] (1) Melting and semi-continuous casting: Melting temperature 740℃, Mg ingots are added to the material frame and pressed into the melt and stirred. High-purity Ar gas is used for refining and degassing the melt. Mechanical stirring is used for in-furnace stirring for 25 minutes. After removing the surface slag, it is allowed to stand for 15 minutes. Filtration is carried out using plate-type double-stage filtration and tubular filtration. Semi-continuous casting temperature 705℃, casting speed 45mm / min, and crystallizer cooling water flow rate 129m³ / min. 3 / h;

[0080] (2) Homogenization treatment: First-stage homogenization temperature 440℃, holding time 8h; Second-stage homogenization temperature 520℃, holding time 8h.

[0081] (3) Hot rolling: initial rolling temperature 480℃, final rolling temperature 360℃;

[0082] (4) Cold rolling: 7mm is thinned to 0.2mm, and the metallographic intermediate annealing temperature during the cold rolling process is 330℃;

[0083] (5) Finished product annealing: annealing temperature 150℃.

[0084] The aluminum alloy sheet and strip produced by this composition and process exhibits coarse second-phase dimensions, with an average grain diameter of 21 μm. It has a tensile strength of 335 MPa, a yield strength of 225 MPa, an elongation of 12.0%, and cracks upon 180° bending. The tensile strength and formability do not meet the technical requirements for aluminum materials in 3C products. This is due to slow casting speed and insufficient cooling water, leading to inadequate cooling intensity. The coarse compounds precipitate from the melt during solidification due to insufficient cooling, ultimately resulting in unsatisfactory performance.

[0085] Comparative Example 2: Comparative Example 2 is a 5-series aluminum alloy sheet / strip without rare earth element Y. The contents of other elements are as follows: Mg=5.9%; Fe=0.25%; Si=0.08%; Cr=0.03%; Cu=0.02%; Mn=0.03%; Zn=0.01%; Ti=0.02%. The preparation process is the same as in Example 1. The aluminum alloy sheet / strip prepared by this composition and process has a coarse second phase size, with an average grain diameter of 21 μm, a tensile strength of 322 MPa, a yield strength of 216 MPa, an elongation of 10.0%, and cracks upon 180° bending. The tensile strength and formability do not meet the technical requirements of 3C products for aluminum materials.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the specific implementation of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the pending claims.

Claims

1. A method for preparing 5-series aluminum alloy sheet and strip containing rare earth element Y, characterized in that, Includes the following steps: Step 1: Prepare the alloy composition according to the following mass percentages: 0.05%≤Y<0.30%; 4.5%<Mg≤6.5%; 0.05<Fe<0.30%; 0.03<Si<0.20%; 0.01<Cr<0.30%; 0.01<Cu<0.25%; 0.01<Mn<0.30; 0.01≤Zn<0.40; 0.01≤Ti≤0.20%, with the balance being Al and unavoidable impurities. Step two involves smelting and semi-continuous casting the prepared alloy composition. The smelting temperature is 755~770℃. Y is added in the form of Al-Y binary alloy ingots. When adding Y, the Al-Y binary alloy ingots and Mg ingots are added to the material frame, pressed into the melt, and thoroughly stirred. The melt is refined and degassed using high-purity Ar gas powder injection. Mechanical stirring is used for in-furnace stirring for 20~30 minutes. After removing the surface slag, the melt is allowed to stand in the furnace for 20~25 minutes and then filtered using a plate-type two-stage filtration and a tubular filtration method. Semi-continuous casting temperature: 700~720℃, casting speed: 48~55mm / min, crystallizer cooling water flow rate: 138~159m³ / min 3 / h; Step 3: Perform a two-stage heat treatment on the prepared casting. The first stage heat treatment temperature is 400℃~450℃ and the holding time is 4~12h. The second stage heat treatment temperature is 470℃~520℃ and the holding time is 6~12h. Step 4: Hot rolling, with an initial rolling temperature of 450~490℃ and a final rolling temperature of 320℃~360℃; Step 5, cold rolling, with 8 to 15 cold rolling passes, a deformation rate of 10% to 30% per pass, and a total deformation rate of 70% to 98%. The intermediate annealing temperature during the cold rolling process is 280℃ to 330℃. Step 6: Anneal the finished product at a temperature of 120~220℃.

2. The method for preparing a 5-series aluminum alloy sheet and strip containing rare earth element Y according to claim 1, characterized in that: 0.05%≤Y＜0.25%。 3. The method for preparing a 5-series aluminum alloy sheet and strip containing rare earth element Y according to claim 1, characterized in that: The thickness of the cold-rolled sheet is 0.1~0.5mm.

4. A 5-series aluminum alloy sheet / strip containing rare earth element Y, prepared by any one of claims 1-3, characterized in that: The composition of aluminum alloy sheet and strip, by mass percentage, is as follows: 0.05%≤Y<0.30%; 4.5%<Mg≤6.5%; 0.05<Fe<0.30%; 0.03<Si<0.20%; 0.01<Cr<0.30%; 0.01<Cu<0.25%; 0.01<Mn<0.30; 0.01≤Zn<0.40; 0.01≤Ti≤0.20%, with the balance being Al and unavoidable impurities; the aluminum alloy sheet and strip has a tensile strength ≥360MPa, a yield strength ≥260MPa, an elongation ≥10%, and does not crack when bent at 180°.

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