High-corrosion-resistance aluminum alloy plate and preparation method thereof

Abstract

The invention belongs to the technical field of aluminum alloys and processing thereof, and discloses a high-corrosion-resistance aluminum alloy plate which comprises the following components: 5.5-6.5% of Mg, less than 0.2% of Fe, less than 0.15% of Si, 0.2-0.5% of Mn, 0.01-0.015% of Ti, less than 0.02% of Cu and the balance of Al and inevitable impurities. The high-corrosion-resistance aluminum alloy plate is prepared through the steps of casting, homogenization, hot rolling, cold rolling, intermediate annealing, secondary intermediate annealing, secondary cold rolling, finished product annealing and the like. The mechanical properties of the aluminum alloy plate prepared through the method are as follows: the tensile strength is 380-400 MPa, the yield strength is 280-320 MPa, and the ductility is 10-15%; and the finished plate has no corrosion spot after being subjected to a neutral salt spray test for 48 hours. The aluminum alloy plate prepared by the invention has high corrosion resistance and high mechanical property, and can meet the requirements of the middle frame of the mobile phone.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum alloy and its processing, and particularly relates to a high-corrosion-resistant aluminum alloy plate and a preparation method thereof. BACKGROUND

[0002] At present, the back plate of a mobile phone is mainly prepared from glass, and with the gradual increase of the size of the mobile phone, the strength requirement of the part playing a supporting role is higher and higher. The middle frame is a key load-bearing and anti-falling structural part of the mobile phone, and once corrosion occurs, especially pitting corrosion or intergranular corrosion, the mechanical strength will decrease sharply. A corroded middle frame is more likely to break or deform when subjected to slight impact or falling, and loses the protection effect on the screen and internal elements. Therefore, it is necessary to improve the strength while maintaining good corrosion resistance.

[0003] At present, the strength of the 5 series alloy is mainly improved by increasing the content of Mg and Cu elements, but the addition of Mg and Cu elements can easily accelerate the corrosion process, so it is necessary to balance the strength and corrosion resistance through composition and process adjustment. SUMMARY

[0004] Therefore, the application provides a high-corrosion-resistant aluminum alloy plate and a preparation method thereof, and aims to solve the problems of insufficient strength and corrosion resistance of the existing 5 series alloy.

[0005] The application is implemented by using the following technical solutions: To achieve the above-mentioned purpose, the application provides a high-corrosion-resistant aluminum alloy plate, and the composition of the aluminum alloy plate is as follows in terms of mass percentage: Mg 5.5-6.5%, Fe <0.2%, Si <0.15%, Mn 0.2-0.5%, Ti 0.01-0.015%, Cu <0.02%, and the balance is Al and unavoidable impurities.

[0006] The application also provides a preparation method of the high-corrosion-resistant aluminum alloy plate, which comprises the following steps: S1. Casting: melt aluminum and alloy raw materials into aluminum liquid, and cast into ingots or blanks to provide initial blanks for subsequent processing; The casting smelting temperature is controlled at 730-780 DEG C. S2. Homogenization process: homogenization treatment is performed on the ingot prepared in step S1; The homogenization treatment temperature is 520 DEG C, and the holding time is 6h; S3. Hot rolling process: the ingot after the homogenization treatment in step S2 is rolled at high temperature; After the ingot is rolled, the thickness of the plate is 3-4mm; S4. Cold rolling process: the plate after the hot rolling in step S3 is rolled at room temperature; The thickness of the plate after cold rolling is 0.8-1.2mm. S5. Intermediate annealing: for eliminating work hardening and restoring material plasticity, so as to subsequent cold rolling processing; The temperature of the intermediate annealing is 380-420 DEG C, and the holding time is 2-3h. S6. Secondary intermediate annealing; The temperature of the secondary intermediate annealing is 140-160 DEG C, and the holding time is 90-100h. S7. Secondary cold rolling process; The thickness of the plate after secondary cold rolling is 0.3-0.5mm. S8. Product annealing: final heat treatment, annealing according to product requirements, to adjust the material structure and performance.

[0007] Further, in the step S3, the hot rolling final rolling temperature is 320 DEG C-340 DEG C, and the maximum deformation of hot rolling is ≤40%.

[0008] Further, in the step S5, after intermediate annealing, quenching treatment is immediately carried out, the quenching solution is water, and the temperature of the quenching solution is 50-80 DEG C.

[0009] Further, in the step S8, the annealing temperature of the product annealing is 180-200 DEG C, and the holding time is 8-10h. Beneficial effects

[0010] The application provides a high corrosion-resistant aluminum alloy plate and a preparation method thereof, and the two innovations are as follows: ①strictly controlling the content of Cu element, the addition of Cu element can significantly reduce the corrosion resistance, mainly reflected in reducing the surface activity and inhibiting the occurrence of pitting corrosion; ②adopting a secondary intermediate annealing process scheme, using low-temperature long-time intermediate annealing, so that the Mg-containing phase is preferentially precipitated at the grain boundary, and the long-time product annealing is used to spheroidize the Mg-containing phase at the grain boundary and discontinuously distribute the Mg-containing phase, so that the second phase at the grain boundary is spheroidized and discontinuously distributed, and the corrosion rate is greatly reduced. The two innovations can inhibit the occurrence of pitting corrosion and control the development of pitting corrosion, and greatly improve the corrosion resistance in 48h neutral salt spray test.

[0011] Due to the high Mg element, hot rolling is prone to cracking, therefore, the hot rolling deformation amount needs to be controlled in a small range, and the hot rolling temperature is kept above the recrystallization temperature, so as to continuously increase the dynamic recrystallization and soften the plate, and prevent hot rolling cracking.

[0012] After the first intermediate annealing, low-temperature water quenching is used, and the purpose is to dissolve the Mg-containing phase in the plate in the high-temperature annealing, and promote the precipitation of the Mg-containing phase in the secondary intermediate annealing process.

[0013] Additional advantages, objects, and features of the application will be apparent to those skilled in the art upon examination of the following detailed description, it being understood that each BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 A flow chart of a method for preparing a high corrosion-resistant aluminum alloy plate according to the present application. DETAILED DESCRIPTION

[0015] In order to make the technical solutions, advantages and objectives of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without any inventive effort fall within the protection scope of the present application.

[0016] The present application provides a high corrosion-resistant aluminum alloy plate, the composition of the aluminum alloy plate is as follows in terms of mass percentage: Mg 5.5-6.5%, Fe <0.2%, Si <0.15%, Mn 0.2-0.5%, Ti 0.01-0.015%, Cu <0.02%, and the balance being Al and unavoidable impurities.

[0017] As shown in Figure 1 The present application also provides a method for preparing a high corrosion-resistant aluminum alloy plate, comprising the following steps: S1. Casting: melting aluminum and alloy raw materials into aluminum liquid, and casting into ingots or billets to provide initial billets for subsequent processing; The casting smelting temperature is controlled at 730-780℃; S2. Homogenization process: homogenizing the ingot prepared in step S1; The homogenization temperature is 520℃, and the holding time is 6h; S3. Hot rolling process: rolling the ingot after the homogenization process in step S2 at high temperature; After the ingot is rolled, the thickness of the plate is 3-4mm; the hot rolling final rolling temperature is 320℃-340℃, and the maximum deformation of hot rolling is ≤40%; S4. Cold rolling process: rolling the plate after the hot rolling in step S3 at room temperature; After the plate is cold-rolled, the thickness of the plate is 0.8-1.2mm; S5. Intermediate annealing: used to eliminate work hardening and restore material plasticity for subsequent cold rolling processing; The temperature of the intermediate annealing is 380-420 DEG C, and the temperature is kept for 2-3 hours. After the intermediate annealing, quenching treatment is immediately carried out, the quenching solution is water, and the temperature of the quenching solution is 50-80 DEG C. S6. Secondary intermediate annealing. The temperature of the secondary intermediate annealing is 140-160 DEG C, and the temperature is kept for 90-95 hours. S7. Secondary cold rolling process. After the secondary cold rolling, the thickness of the plate is 0.3-0.5 mm. S8. Product annealing: final heat treatment, annealing is carried out according to product requirements to adjust the structure and performance of the material. The annealing temperature of the product annealing is 180-200 DEG C, and the temperature is kept for 8-10 hours.

[0018] The mechanical properties of the aluminum alloy plate prepared by the method are as follows: tensile strength 380-400 MPa, yield strength 280-320 MPa, and elongation 10-15%; and the finished plate has no corrosion point in the neutral salt spray test for 48 hours. Embodiment

[0019] The embodiment discloses a preparation method of a high-corrosion-resistant aluminum alloy plate, and the specific steps are as follows: S1. Casting: according to the proportioning of alloy element components, aluminum and alloy raw materials are melted into aluminum liquid to cast into ingots or blanks, thereby providing initial blanks for subsequent processing. The components of the aluminum alloy plate in the embodiment are as follows in terms of mass percentage: Mg 6.5%, Fe 0.1%, Si 0.1%, Mn 0.5%, Ti 0.01%, Cu 0.005%, other impurity elements 0.02%, and the balance is Al; and the casting melting temperature is controlled at 730 DEG C. S2. Homogenization process: the ingot prepared in step S1 is subjected to homogenization treatment. The temperature of the homogenization treatment is 520 DEG C, and the temperature is kept for 6 hours. S3. Hot rolling process: the ingot subjected to the homogenization treatment in step S2 is rolled at high temperature. After the ingot is rolled, the thickness of the plate is 3 mm; the final hot rolling temperature is 320 DEG C, and the maximum deformation of the hot rolling is 20%. S4. Cold rolling process: the plate subjected to the hot rolling in step S3 is rolled at room temperature. After the plate is cold rolled, the thickness of the plate is 0.8 mm. S5. Intermediate annealing: used for eliminating work hardening and restoring material plasticity, so as to facilitate subsequent cold rolling processing. The temperature of the intermediate annealing is 420 DEG C, and the holding time is 2 hours; immediately after the intermediate annealing, quenching treatment is performed, the quenching solution is water, and the temperature of the quenching solution is 80 DEG C; S6. Secondary intermediate annealing; The temperature of the secondary intermediate annealing is 160 DEG C, and the holding time is 100 hours; S7. Secondary cold rolling process; After the secondary cold rolling, the thickness of the plate is 0.3 mm; S8. Product annealing: final heat treatment, annealing is performed according to product requirements to adjust the structure and performance of the material; The annealing temperature of the product annealing is 180 DEG C, and the holding time is 10 hours. Embodiment

[0020] The embodiment discloses a preparation method of a high-corrosion-resistant aluminum alloy plate. The preparation method is the same as that in Embodiment 1. The difference lies in the component proportion of the alloy elements of the aluminum alloy plate. In the embodiment, the content of Mg is 5.5%. Embodiment

[0021] The embodiment discloses a preparation method of a high-corrosion-resistant aluminum alloy plate. The preparation method is the same as that in Embodiment 1. The difference lies in the temperature of the secondary intermediate annealing. In the embodiment, the temperature of the secondary intermediate annealing is 140 DEG C.

[0022] Comparative Example 1 The comparative example discloses a preparation method of an aluminum alloy plate. The preparation method is the same as that in Embodiment 1. The difference lies in the component proportion of the alloy elements of the aluminum alloy plate. In the comparative example, the content of Cu is 0.3%.

[0023] Comparative Example 2 The comparative example discloses a preparation method of an aluminum alloy plate. The preparation method is the same as that in Embodiment 1. The difference lies in the operation of the secondary intermediate annealing. In the comparative example, the temperature of the secondary intermediate annealing is 90 DEG C, and the holding time is 80 hours.

[0024] The mechanical property values and the neutral salt spray test of the alloy plates prepared in Embodiments 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0025] Table 1

[0026] It can be seen from Table 1 that the alloy plate prepared by the method has high corrosion resistance and high mechanical properties, and can meet the requirements of a mobile phone middle frame. The mechanical properties of the alloy plate prepared by the method are as follows: tensile strength 380-400 MPa, yield strength 280-320 MPa, and elongation 10-15%; and the finished product plate has no corrosion point in a neutral salt spray test for 48 h.

[0027] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, and they should be covered in the protection scope of the present application.

Claims

1. A high corrosion resistant aluminum alloy sheet material, characterized by: The aluminum alloy plate has the following components in percentage by mass: Mg 5.5-6.5%, Fe <0.2%, Si <0.15%, Mn 0.2-0.5%, Ti 0.01-0.015%, Cu <0.02%, and the balance of Al and inevitable impurities.

2. A method of producing a high corrosion-resistant aluminum alloy sheet according to claim 1, characterized by, The method comprises the following steps: S1. Casting: melting aluminum and alloy raw materials into aluminum liquid, and casting into ingots or blanks to provide initial blanks for subsequent processing; The casting smelting temperature is controlled at 730-780℃; S2. Homogenization process: homogenizing the ingot prepared in step S1; The homogenization temperature is 520℃, and the holding time is 6h; S3. Hot rolling process: rolling the ingot after the homogenization process in step S2 at high temperature; After the ingot is rolled, the thickness of the plate is 3-4mm; S4. Cold rolling process: rolling the plate after the hot rolling process in step S3 at room temperature; After the plate is cold-rolled, the thickness of the plate is 0.8-1.2mm; S5. Intermediate annealing: used to eliminate work hardening and restore material plasticity for subsequent cold rolling processing; The intermediate annealing temperature is 380-420℃, and the holding time is 2-3h; S6. Second intermediate annealing; The second intermediate annealing temperature is 140-160℃, and the holding time is 90-100h; S7. Second cold rolling process; After the second cold rolling, the thickness of the plate is 0.3-0.5mm; S8. Product annealing: final heat treatment, annealing according to product requirements to adjust the organization and performance of the material.

3. The method of claim 2, wherein the high corrosion resistant aluminum alloy sheet is prepared by the steps of: In step S3, the hot rolling finish rolling temperature is 320-340℃, and the maximum deformation of hot rolling is ≤40%. ​ 4. The method of claim 3, wherein the high corrosion resistant aluminum alloy sheet is prepared by the steps of: After the intermediate annealing in step S5, quenching treatment is immediately performed, the quenching solution is water, and the temperature of the quenching solution is 50-80℃. ​ 5. The method of claim 4, wherein the high corrosion resistant aluminum alloy sheet is prepared by the steps of: In step S8, the annealing temperature of the product annealing is 180-200℃, and the holding time is 8-10h. ​

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