High-strength and high-thermal-conductivity 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-strength and high-thermal-conductivity aluminum alloy plate which comprises the following components: 4.0-5.0% of Mg, less than 0.2% of Fe, less than 0.15% of Si, less than 0.2% of Mn, 0.02-0.03% of Ti, 0.2-0.4% of Er, 0.1-0.15% of Zr and the balance of Al and inevitable impurities. The high-strength and high-thermal-conductivity aluminum alloy plate is prepared through the steps of casting, homogenization, hot rolling, cold rolling, intermediate annealing, secondary cold rolling, finished product annealing and the like. According to the mechanical properties of the aluminum alloy plate prepared through the method, the tensile strength ranges from 480 MPa to 510 MPa, the yield strength ranges from 380 MPa to 420 MPa, the ductility ranges from 7% to 9%, the heat conductivity ranges from 130 W / mK to 160 W / mK, and the bending performance is that no crack exists when the aluminum alloy plate is bent by 180 degrees. The aluminum alloy plate prepared by the preparation method disclosed by the invention has high thermal conductivity and high mechanical property, and can meet the requirements of 5G mobile phone middle plates.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy and its processing technology, specifically relating to a high-strength, high-thermal-conductivity aluminum alloy sheet and its preparation method. Background Technology

[0002] With the widespread adoption of 5G phones, the power consumption of these devices has significantly increased, leading to a substantial rise in heat generation. Furthermore, the increasing use of glass back panels in phones further reduces heat dissipation capacity. To improve heat dissipation, higher demands are placed on the thermal performance of the phone's mid-plate. Currently, mid-plates are made from 5-series alloys, with a thermal conductivity of around 110 W / mK, which is insufficient for current applications. Moreover, the increasing size of 5G phones places greater demands on the strength of the mid-plate. Therefore, mid-plate materials with higher thermal conductivity and mechanical properties are required.

[0003] However, increasing the strength of 5-series alloys generally involves increasing the Mg content to enhance solid solution strengthening. But solid solution strengthening leads to increased lattice distortion in the matrix, affecting electron pathways and causing a decrease in thermal conductivity. Therefore, simultaneously improving both strength and thermal conductivity is quite challenging. Summary of the Invention

[0004] In view of this, the present invention proposes a high-strength, high-thermal-conductivity aluminum alloy sheet and its preparation method. The present invention aims to solve the problem that existing aluminum alloy sheets cannot simultaneously achieve high thermal conductivity and high mechanical properties, making it difficult to meet the requirements of the mid-plate of 5G mobile phones.

[0005] This invention is achieved using the following technical solution:

[0006] To achieve the above objectives, the present invention provides a high-strength, high-thermal-conductivity aluminum alloy sheet, wherein the composition of the aluminum alloy sheet by mass percentage is: Mg 4.0~5.0%, Fe<0.2%, Si<0.15%, Mn<0.2%, Ti 0.02~0.03%, Er0.2~0.4%, Zr 0.1~0.15%, with the balance being Al and unavoidable impurities.

[0007] This invention also provides a method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet, comprising the following steps:

[0008] S1. Casting: Melting aluminum and alloy raw materials into molten aluminum and casting them into ingots or billets to provide initial blanks for subsequent processing;

[0009] Among them, the casting and smelting temperature is controlled at 730~780℃;

[0010] S2. Homogenization process: The ingot prepared in step S1 is homogenized using a three-stage homogenization process;

[0011] Three-level homogenization system:

[0012] ① First stage: Homogenization temperature is 270~300℃, and the temperature is maintained for 10~15 hours;

[0013] ② Second stage, homogenization temperature is 420~450℃, and the temperature is maintained for 10~12h;

[0014] ③ The third electrode has a homogenization temperature of 500~520℃ and is kept at that temperature for 6~8 hours;

[0015] S3. Hot rolling process: Rolling the ingot after homogenization treatment in step S2 at high temperature;

[0016] After the ingot is rolled, the thickness of the plate is 6~7mm;

[0017] S4. Cold rolling process: Rolling the sheet material after hot rolling in step S3 at room temperature;

[0018] The thickness of the sheet after cold rolling is 1~2mm;

[0019] S5. Intermediate annealing: Used to eliminate work hardening and restore the plasticity of the material for subsequent cold rolling.

[0020] S6. Secondary cold rolling process;

[0021] After the second cold rolling, the thickness of the sheet is 0.5~0.8mm;

[0022] S7. Finished product annealing: Final heat treatment, annealing is carried out according to product requirements to adjust the microstructure and properties of the material.

[0023] Furthermore, in step S3, the hot rolling start temperature is 460℃~520℃.

[0024] Furthermore, in step S5, the intermediate annealing temperature is 440~480℃, and the holding time is 2~3h.

[0025] Furthermore, in step S7, the annealing temperature of the finished product is 180~200℃, and the holding time is 2~3h.

[0026] Beneficial effects:

[0027] This invention provides a high-strength, high-thermal-conductivity aluminum alloy sheet and its preparation method. Its innovation lies in using the composite addition of Er and Zr elements to replace the reduction of Mg. Mg, due to its solid solution strengthening effect in 5-series alloys, significantly reduces thermal conductivity but has a notable effect on improving mechanical properties. To simultaneously improve both mechanical and thermal conductivity, this invention reduces the Mg element, minimizing its solid solution effect on thermal conductivity, and compensates for the loss in mechanical properties by compositely adding Er and Zr. Furthermore, the composite addition of Er and Zr enables precipitation strengthening, thus having minimal impact on the reduction of thermal conductivity, achieving a simultaneous improvement in both mechanical and thermal properties.

[0028] To ensure the added Er and Zr elements fully exert their strengthening effect, this invention employs a three-stage homogenization process. In the first stage, Al3Er cores are effectively precipitated. In the second stage, an Al3Zr shell is precipitated, ensuring that the effective components of Al3Zr do not dissolve at high temperatures. In the third stage, at high temperatures, the Fe and Mn-containing high-temperature second phase is fully dissolved and refined. This homogenization process effectively protects the effective components of Al3Zr, allowing them to continuously pin dislocations in subsequent processes and improve alloy strength.

[0029] To prevent Zr poisoning in the refining agent, this invention increases the Ti content to increase the effective content of the refining agent. On the other hand, it strictly controls the melting temperature within the range of 730-780℃. This is because above 780℃, Zr reacts excessively with TiB2, consuming TiB2; while below 730℃, Al3Zr solidifies and agglomerates directly, which is not conducive to the effective addition of Zr.

[0030] The aluminum alloy sheet prepared by the method of the present invention has the following mechanical properties: tensile strength 480~510MPa, yield strength 380~420MPa, elongation 7~9%, thermal conductivity 130~160W / mK; and bending performance: no cracks after 180° bending.

[0031] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0032] Figure 1 This is a flowchart of a method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet according to the present invention. Detailed Implementation

[0033] To make the technical solutions, advantages, and objectives of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of this application.

[0034] This invention provides a high-strength, high-thermal-conductivity aluminum alloy sheet. The composition of the aluminum alloy sheet by mass percentage is: Mg 4.0~5.0%, Fe<0.2%, Si<0.15%, Mn<0.2%, Ti 0.02~0.03%, Er 0.2~0.4%, Zr 0.1~0.15%, with the balance being Al and unavoidable impurities.

[0035] like Figure 1 As shown, the present invention also provides a method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet, comprising the following steps:

[0036] S1. Casting: Melting aluminum and alloy raw materials into molten aluminum and casting them into ingots or billets to provide initial blanks for subsequent processing;

[0037] Among them, the casting and smelting temperature is controlled at 730~780℃;

[0038] S2. Homogenization process: The ingot prepared in step S1 is homogenized using a three-stage homogenization process;

[0039] Three-level homogenization system:

[0040] ① First stage: Homogenization temperature is 270~300℃, and the temperature is maintained for 10~15 hours;

[0041] ② Second stage, homogenization temperature is 420~450℃, and the temperature is maintained for 10~12h;

[0042] ③ The third electrode has a homogenization temperature of 500~520℃ and is kept at that temperature for 6~8 hours;

[0043] S3. Hot rolling process: Rolling the ingot after homogenization treatment in step S2 at high temperature;

[0044] The hot rolling temperature is 460℃~520℃, and the thickness of the plate after ingot rolling is 6~7mm.

[0045] S4. Cold rolling process: Rolling the sheet material after hot rolling in step S3 at room temperature;

[0046] The thickness of the sheet after cold rolling is 1~2mm;

[0047] S5. Intermediate annealing: Used to eliminate work hardening and restore the plasticity of the material for subsequent cold rolling.

[0048] The intermediate annealing process involves annealing at a temperature of 440-480℃ for 2-3 hours.

[0049] S6. Secondary cold rolling process;

[0050] After the second cold rolling, the thickness of the sheet is 0.5~0.8mm;

[0051] S7. Finished product annealing: Final heat treatment, annealing is carried out according to product requirements to adjust the microstructure and properties of the material;

[0052] The annealing temperature for the finished product is 180~200℃, and the holding time is 2~3h.

[0053] The aluminum alloy sheet prepared by the method of the present invention has the following mechanical properties: tensile strength 480~510MPa, yield strength 380~420MPa, elongation 7~9%, thermal conductivity 130~160W / mK, and bending performance: no cracking after 180° bending.

[0054] Example 1

[0055] This embodiment discloses a method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet, the specific steps of which are as follows:

[0056] S1. Casting: Smelting aluminum and alloy raw materials into molten aluminum according to the alloy element composition ratio, and casting them into ingots or billets to provide initial billets for subsequent processing;

[0057] In this embodiment, the composition of the aluminum alloy sheet by mass percentage is: Mg 5.0%, Fe 0.15%, Si 0.1%, Mn 0.1%, Ti 0.03%, Er 0.4%, Zr 0.15%, with the balance being Al and unavoidable impurities; the casting and smelting temperature is controlled at 730℃.

[0058] S2. Homogenization process: The ingot prepared in step S1 is homogenized using a three-stage homogenization process;

[0059] Three-level homogenization system:

[0060] ① First stage: Homogenization temperature is 300℃, and the temperature is maintained for 10 hours;

[0061] ② Second stage, homogenization temperature is 450℃, and the temperature is maintained for 10 h;

[0062] ③ The third electrode, homogenization temperature is 520℃, and it is kept at this temperature for 6 hours;

[0063] S3. Hot rolling process: Rolling the ingot after homogenization treatment in step S2 at high temperature;

[0064] The hot rolling temperature is 460℃, and the thickness of the plate after ingot rolling is 6mm.

[0065] S4. Cold rolling process: Rolling the sheet material after hot rolling in step S3 at room temperature;

[0066] The thickness of the sheet after cold rolling is 1mm;

[0067] S5. Intermediate annealing: Used to eliminate work hardening and restore the plasticity of the material for subsequent cold rolling.

[0068] The intermediate annealing was performed at a temperature of 480℃ for 2 hours.

[0069] S6. Secondary cold rolling process;

[0070] After the second cold rolling, the thickness of the sheet is 0.5 mm;

[0071] S7. Finished product annealing: Final heat treatment, annealing is carried out according to product requirements to adjust the microstructure and properties of the material;

[0072] The annealing temperature for the finished product is 200℃, and the holding time is 2 hours.

[0073] Example 2

[0074] This embodiment discloses a method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet, which is the same as the method in Example 1. The difference lies in the composition ratio of the alloying elements in the aluminum alloy sheet. In this embodiment, the content of Mg is 4.0% and the content of Er is 0.2%.

[0075] Example 3

[0076] This embodiment discloses a method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet, which is the same as the method in Example 1. The difference lies in the homogenization process; in this embodiment, the three-stage homogenization process is as follows:

[0077] ① First stage: Homogenization temperature is 270℃, and the temperature is maintained for 15 hours;

[0078] ② Second stage, homogenization temperature is 420℃, and the temperature is maintained for 12 h;

[0079] ③ The third electrode, homogenization temperature is 500℃, and it is kept at this temperature for 8 hours.

[0080] Comparative Example 1

[0081] This comparative example discloses a method for preparing an aluminum alloy sheet, which is the same as the method in Example 1. The difference lies in the composition ratio of the alloying elements in the aluminum alloy sheet; in this comparative example, the content of Mg is 5.5% and the content of Er is 0%.

[0082] Comparative Example 2

[0083] This comparative example discloses a method for preparing aluminum alloy sheet, which is the same as the method in Example 1. The difference lies in the homogenization process; in this comparative example, the three-stage homogenization process is as follows:

[0084] ① First stage: Homogenization temperature is 220℃, and the temperature is maintained for 15 hours;

[0085] ② Second stage, homogenization temperature is 420℃, and the temperature is maintained for 6 hours;

[0086] ③ The third electrode, homogenization temperature is 480℃, and it is kept at this temperature for 8 hours.

[0087] The mechanical properties and electrical conductivity of the alloy plates obtained in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0088] Table 1

[0089] As shown in Table 1, the alloy sheet prepared by the method of this invention combines high thermal conductivity and high mechanical properties, meeting the requirements of the mid-plate of 5G mobile phones. The mechanical properties of the alloy sheet prepared by the method of this invention are: tensile strength 480~510MPa, yield strength 380~420MPa, elongation 7~9%, thermal conductivity 130~160W / mK, and bending performance: no cracking after 180° bending.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A high-strength, high-thermal-conductivity aluminum alloy sheet, characterized in that: The composition of the aluminum alloy sheet by mass percentage is: Mg 4.0~5.0%, Fe<0.2%, Si<0.15%, Mn<0.2%, Ti 0.02~0.03%, Er 0.2~0.4%, Zr 0.1~0.15%, with the balance being Al and unavoidable impurities.

2. A method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet as described in claim 1, characterized in that, Includes the following steps: S1. Casting: Melting aluminum and alloy raw materials into molten aluminum and casting them into ingots or billets to provide initial blanks for subsequent processing; Among them, the casting and smelting temperature is controlled at 730~780℃; S2. Homogenization process: The ingot prepared in step S1 is homogenized using a three-stage homogenization process; Three-level homogenization system: ① First stage: Homogenization temperature is 270~300℃, and the temperature is maintained for 10~15 hours; ② Second stage, homogenization temperature is 420~450℃, and the temperature is maintained for 10~12h; ③ The third electrode has a homogenization temperature of 500~520℃ and is kept at that temperature for 6~8 hours; S3. Hot rolling process: Rolling the ingot after homogenization treatment in step S2 at high temperature; After the ingot is rolled, the thickness of the plate is 6~7mm; S4. Cold rolling process: Rolling the sheet material after hot rolling in step S3 at room temperature; The thickness of the sheet after cold rolling is 1~2mm; S5. Intermediate annealing: Used to eliminate work hardening and restore the plasticity of the material for subsequent cold rolling. S6. Secondary cold rolling process; After the second cold rolling, the thickness of the sheet is 0.5~0.8mm; S7. Finished product annealing: Final heat treatment, annealing is carried out according to product requirements to adjust the microstructure and properties of the material.

3. The method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet according to claim 2, characterized in that: In step S3, the hot rolling start temperature is 460℃~520℃.

4. The method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet according to claim 3, characterized in that: In step S5, the intermediate annealing temperature is 440~480℃, and the holding time is 2~3h.

5. The method for preparing a high-strength, high-thermal-conductivity aluminum alloy sheet according to claim 5, characterized in that: In step S7, the annealing temperature of the finished product is 180~200℃, and the holding time is 2~3h.

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