Preparation method of high-thermal-conductivity high-forming 6-series anodized aluminum sheet

Abstract

The application discloses a preparation method of a high-thermal-conductivity high-forming 6-series anodic aluminum sheet. The chemical composition of the 6-series anodic aluminum sheet comprises the following components in a mass percentage: Si 0.3-0.5%, Fe 0.08-0.20%, Cu <0.10%, Mn <0.03%, Mg 0.4-0.6%, Ti 0.010-0.025%, and the balance of aluminum and inevitable impurities. The 6-series anodic aluminum sheet is prepared through smelting, casting, homogenization, hot rolling, cold rolling, solid solution quenching, artificial aging and tension leveling. The thickness of the aluminum alloy sheet is 0.5-2.0 mm, the tensile strength is 180-240 MPa, the yield strength is 150-210 MPa, the elongation is greater than or equal to 12%, the work hardening index n value is greater than or equal to 0.60, the plastic strain ratio r value is greater than or equal to 0.23, the average grain size of the surface and the transverse direction is 35-80 mu m, and the thermal conductivity is greater than 200 W / (m*K).

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aluminum alloy strip preparation, and particularly relates to a preparation method of high-thermal-conductivity high-forming 6-series anodized aluminum sheet. BACKGROUND

[0002] Currently, the anodized material used for the notebook computer shell is mainly 5-series aluminum alloy sheet stamped or 6-series aluminum profile processed by CNC. The 5-series aluminum alloy sheet has good forming performance, but low thermal conductivity. The 6-series aluminum profile has good performance, but is high in cost and low in material effective utilization. Currently, the 6-series aluminum alloy sheet has poor forming performance and cannot meet the forming requirements of the notebook computer shell, and is prone to cracking and other problems. With the popularity of AI computers, the requirement of AI chips for heat dissipation is significantly improved. The traditional 5-series aluminum alloy cannot meet the requirements of high power and high heat dissipation of AI chips, and therefore it is urgent to develop a 6-series aluminum alloy sheet with high thermal conductivity and high forming performance for the notebook computer shell.

[0003] Patent application No. 201911372828.9 discloses a high-conductivity 6-series aluminum alloy material and a production process thereof. The high-conductivity 6-series aluminum alloy material is prepared by additionally adding elements B 0.015-0.02%, Gd 0.15-0.18%, homogenizing treatment at a low temperature of 450-500°C, and double-stage aging at 175°C for 9h and at 220°C for 3h after extrusion. The composition design and preparation method are different.

[0004] Patent application No. 201811260377.5 discloses a T6 state aluminum alloy conductive pipe material and a preparation method thereof. The alloy composition of the 6101 is proportioned as follows: Si 0.38%-0.40%, Fe 0.05%-0.10%, Cu 0.05%-0.08%, Mn <0.01%, Mg 0.54%-0.56%, Cr <0.01%, Zn <0.02%, Ti 0.02%-0.04%, Mg / Si = 1.34-1.48, other single elements ≤0.05%, and other impurity elements ≤0.15%. The cast bar is sequentially subjected to homogenization, extrusion, online quenching, stretching and straightening, and double-stage artificial aging to prepare a T6 state aluminum alloy conductive pipe material. The alloy composition is high in purity, and the preparation method is different.

[0005] Patent application number 201810889362.9 discloses a 6-series alloy anodized aluminum sheet / strip for mobile phone frames and its preparation method. By limiting the element Fe to ≤0.08 and subjecting it to a two-stage homogenization treatment at 390~410℃ for 8~12 hours and 530~540℃ for 30~40 hours, followed by hot rolling to a thickness of 4.0~10.0 mm, and then subjected to a long-term solution treatment and aging treatment at 540~570℃ for 1~2 hours, a thick aluminum alloy sheet is finally obtained. However, the low impurity elements prevent the addition of a high proportion of recycled aluminum, limiting its application to thick mobile phone frame sheets.

[0006] Patent application number 202110816103.5 discloses a high-strength anodized aluminum sheet and its preparation method. After homogenization heat treatment (540~560℃ / 3~8 hours + 500~510℃ / 1~6 hours), the ingot is hot-rolled to a final rolling temperature of 360~400℃ without intermediate annealing. The finished product is then cold-rolled and directly subjected to low-temperature solution treatment at 500~520℃ and artificial aging treatment at 150~200℃ / 5~24 hours. This method utilizes the high temperature of the hot-rolled material to precipitate a large amount of second phase, increasing recrystallization nucleation points during the solution treatment process and refining the grain size. However, its drawbacks include the risk of abnormal recrystallization during the hot-rolling stage due to the high initial rolling temperature of 500~510℃ after homogenization, and the risk of uneven precipitation of Mg2Si at the final rolling temperature of 360~400℃, resulting in anodized discoloration lines in the finished product. Furthermore, its forming performance cannot meet the forming requirements of various casing parts for laptops. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing high thermal conductivity and high formability 6-series anodized aluminum thin plates, thereby achieving excellent performance.

[0008] To achieve the objectives of this invention, the following technical solution is adopted:

[0009] A method for preparing a high thermal conductivity and high formability 6-series anodized aluminum sheet, wherein the chemical composition of the aluminum alloy sheet by mass fraction is: Si 0.3~0.5%, Fe 0.08~0.20%, Cu<0.10%, Mn<0.03%, Mg 0.4~0.6%, Ti 0.010~0.025%, with the balance being aluminum and unavoidable impurities.

[0010] A method for preparing a high thermal conductivity and high formability 6-series anodized aluminum sheet: The high thermal conductivity and high formability 6-series anodized aluminum sheet is obtained through melting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and tension straightening. The specific preparation method includes the following steps:

[0011] (1) According to the alloy composition ratio, aluminum ingots, aluminum intermediate alloy ingots and other raw materials are added to the melting furnace, melted and refined in the temperature range of 720-760℃, slag removed, transferred to the holding furnace, and left to stand for 0.5-4 hours. Then casting begins at a casting temperature of 680-710℃ and a casting speed of 45-60mm / min to cast flat ingots with a thickness of 400-600mm.

[0012] (2) After milling the flat ingot, put it into a heating furnace and keep it at 530-600℃ for 1-12 hours for homogenization heat treatment. Then cool it down to 400-500℃ for rolling. The hot rolling final thickness is 3-10mm and the final rolling temperature is 250-320℃.

[0013] (3) The hot-rolled coil is cold-rolled to the finished thickness with a cold rolling rate of 60-95%, and then solution treatment is performed. The cold rolling process can also be divided into two cold rolling processes. The processing rate of the first cold rolling is not less than 40%, and the processing rate of the second cold rolling is 50-70%. An intermediate annealing is performed between the two cold rolling processes. The annealing temperature is 350-485℃ and the annealing time is 30-60s.

[0014] (4) After cold rolling to the finished thickness, solution treatment is carried out at a temperature of 530-580℃ and a holding time of 15-120 seconds. Water cooling or air cooling is used for quenching, followed by aging treatment at a temperature of 150-250℃ and a holding time of 1-24 hours.

[0015] (5) After aging treatment, the sheet metal undergoes tensile straightening to obtain a good sheet shape, eliminate internal stress, and ensure that the stamping springback meets the requirements. The characteristics of the resulting finished product are: thickness 0.5-2.0 mm, tensile strength 180~240 MPa, yield strength 150~210 MPa, elongation ≥12%, work hardening index n ≥0.60, plastic strain ratio r ≥0.23, thermal conductivity λ>200 W / (m•K), and average grain size on the surface and transverse sides 35~80 μm. It possesses good formability and can be used for forming various casings of laptops.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention leverages the combined properties of 6-series materials, including forming, thermal conductivity, and anodizing, to synergistically regulate the material's composition, grain size, and microstructure. A well-designed high-temperature homogenization process at 530-600℃ eliminates dendrite segregation and reduces resistance to electron movement. A low-temperature intermediate annealing process at 350-485℃ avoids significant Mg2Si re-dissolution. Combined with cold rolling and high-temperature solution treatment at 530-580℃, a suitable grain size is achieved, reducing the increased scattering probability and decreased thermal conductivity caused by excessive grain boundaries. The resulting product has a thickness of 0.5-2.0 mm, tensile strength of 180-240 MPa, yield strength of 150-210 MPa, elongation ≥12%, work hardening index n ≥0.60, plastic strain ratio r ≥0.23, thermal conductivity λ>200 W / (m•K), and an average surface and transverse grain size of 35-80 μm. Attached Figure Description

[0018] Figure 1 This is a sample image prepared in Example 1 of the present invention.

[0019] Figure 2 This is a sample image prepared in Example 2 of the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0021] This invention aims to provide a high thermal conductivity and high formability 6-series anodized aluminum sheet, the mass fraction of which is: Si 0.3~0.5%, Fe 0.08~0.20%, Cu<0.10%, Mn<0.03%, Mg 0.4~0.6%, Ti 0.010~0.025%, with the balance being aluminum and unavoidable impurities.

[0022] A high thermal conductivity and high formability 6-series anodized aluminum sheet was obtained by hot rolling, cold rolling, solution quenching, aging, and tension straightening.

[0023] During the melting and casting processes, the rapid solidification and cooling rates prevent atoms in the liquid phase from diffusing quickly enough, leading to unbalanced crystallization. Dendritic segregation also affects the probability of electron scattering, increases resistance to electron movement, and reduces thermal conductivity. Therefore, heat treatment of the as-cast alloy is essential. High-temperature homogenization at 530-600℃ for 1-12 hours can effectively improve microsegregation. Subsequent cooling to 400-500℃ for initial rolling can prevent abnormal grain growth during hot rolling.

[0024] Under large deformation cold rolling conditions, Mg2Si gradually precipitates. Through low-temperature intermediate annealing at 350-485℃, the equiaxability of the grains is improved, and more importantly, a large amount of Mg2Si is prevented from dissolving back.

[0025] By controlling the cold rolling rate to 60-95% and the high-temperature solution treatment at 530-580℃, appropriate grain size is obtained, which reduces the increased probability of electron scattering and the decrease in thermal conductivity caused by excessive grain boundaries, and also ensures the forming performance.

[0026] The following will illustrate this with specific implementation examples.

[0027] Example 1

[0028] A method for preparing a high thermal conductivity and high formability 6-series anodized aluminum thin sheet: The chemical composition of the aluminum alloy sheet / strip, by mass fraction, is: Si 0.32%, Fe 0.15%, Cu 0.02%, Mn 0.02%, Mg 0.45%, Ti 0.015%, with the balance being aluminum and unavoidable impurities. The method for preparing the high thermal conductivity and high formability 6-series anodized aluminum thin sheet involves melting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and tension straightening. The specific preparation method includes the following steps:

[0029] (1) According to the alloy composition ratio, aluminum ingots, aluminum intermediate alloy ingots and other raw materials are added to the melting furnace, melted and refined in the temperature range of 725℃, slag removed, transferred to the holding furnace, and left to stand for 2 hours. Then casting begins at a casting temperature of 710℃ and a casting speed of 52mm / min to cast flat ingots with a thickness of 600mm.

[0030] (2) After milling the flat ingot, it is placed in a heating furnace and kept at 570℃ for 12 hours for homogenization heat treatment. Then it is cooled to 420℃ for rolling. The final thickness of the hot rolling is 5mm and the final rolling temperature is 250℃.

[0031] (3) The hot-rolled coil is cold-rolled to a finished thickness of 2mm with a cold rolling rate of 60%, and then solution treatment is performed.

[0032] (4) After cold rolling to the finished thickness, a solution treatment of 560℃ / 60sec is performed using water cooling, followed by an aging treatment at 180℃ for 10 hours.

[0033] (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping springback meets the requirements.

[0034] The aluminum alloy sheet produced by this invention has a thickness of 2.0 mm, a tensile strength of 192 MPa, a yield strength of 167 MPa, an elongation of 15%, a work hardening index n of 0.68, a plastic strain ratio r of 0.26, a thermal conductivity λ of 220 W / (m•K), and average grain sizes of 70 μm on the surface and 72 μm in the transverse direction.

[0035] Example 2

[0036] A method for preparing a high thermal conductivity and high formability 6-series anodized aluminum sheet: The chemical composition of the aluminum alloy sheet / strip, by mass fraction, is: Si 0.38%, Fe 0.20%, Cu 0.015%, Mn 0.014%, Mg 0.46%, Ti 0.015%, with the balance being aluminum and unavoidable impurities. The method for preparing the high thermal conductivity and high formability 6-series anodized aluminum sheet involves melting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and tension straightening. The specific preparation method includes the following steps:

[0037] (1) According to the alloy composition ratio, aluminum ingots, aluminum intermediate alloy ingots and other raw materials are added to the melting furnace, melted and refined in the temperature range of 760℃, slag removed, transferred to the holding furnace, and left to stand for 1 hour. Then casting begins at a casting temperature of 700℃ and a casting speed of 55mm / min to cast flat ingots with a thickness of 500mm.

[0038] (2) After milling the flat ingot, it is placed in a heating furnace and kept at 580℃ for 5 hours for homogenization heat treatment. Then it is cooled to 450℃ for rolling. The final thickness of the hot rolling is 7mm and the final rolling temperature is 265℃.

[0039] (3) The hot-rolled coil is cold-rolled to 4mm and then cold-rolled to a finished thickness of 1.2mm. The first cold rolling processing rate is 42.86% and the second cold rolling processing rate is 70%. Between the two cold rolling processes, an intermediate annealing at 350℃ / 60sec is performed.

[0040] (4) After cold rolling to the finished thickness, solution treatment is performed at a temperature of 570°C and a holding time of 30 seconds. Air quenching is then used, followed by aging treatment at a temperature of 150°C and a holding time of 20 hours.

[0041] (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping springback meets the requirements.

[0042] The aluminum alloy sheet produced by this invention has a thickness of 1.2 mm, a tensile strength of 250 MPa, a yield strength of 198 MPa, an elongation of 13.5%, a work hardening index n of 0.72, a plastic strain ratio r of 0.25, a thermal conductivity λ of 215 W / (m•K), and average grain sizes of 74 μm on the surface and 78 μm in the transverse direction.

[0043] Example 3

[0044] A method for preparing a high thermal conductivity and high formability 6-series anodized aluminum sheet: The chemical composition of the aluminum alloy sheet / strip, by mass fraction, is: Si 0.40%, Fe 0.18%, Cu 0.001%, Mn 0.001%, Mg 0.60%, Ti 0.025%, with the balance being aluminum and unavoidable impurities. The method for preparing the high thermal conductivity and high formability 6-series anodized aluminum sheet involves melting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and tension straightening. The specific preparation method includes the following steps:

[0045] (1) According to the alloy composition ratio, aluminum ingots, aluminum intermediate alloy ingots and various raw materials are added to the melting furnace, melted and refined in the temperature range of 740℃, slag removed, transferred to the holding furnace, and left to stand for 4 hours. Then casting begins at a casting temperature of 705℃ and a casting speed of 60mm / min to cast flat ingots with a thickness of 600mm.

[0046] (2) After milling the flat ingot, put it into a heating furnace and keep it at 600℃ for 2 hours for homogenization heat treatment. Then cool it down to 500℃ for rolling. The final thickness of the hot rolling is 10mm and the final rolling temperature is 260℃.

[0047] (3) The hot-rolled coil is cold-rolled to 5.0 mm and then cold-rolled to a finished thickness of 1.5 mm. The first cold rolling processing rate is 50%, the second cold rolling processing rate is 70%, and an intermediate annealing at 420℃ / 30 sec is performed between the two cold rolling processes.

[0048] (4) After cold rolling to the finished thickness, solution treatment is performed at a temperature of 580℃ and a holding time of 15 seconds. Air quenching is then used, followed by aging treatment at a temperature of 200℃ and a holding time of 2 hours.

[0049] (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping springback meets the requirements.

[0050] The aluminum alloy sheet produced by this invention has a thickness of 1.50 mm, a tensile strength of 270 MPa, a yield strength of 207 MPa, an elongation of 12.5%, a work hardening index n of 0.66, a plastic strain ratio r of 0.23, a thermal conductivity λ of 208 W / (m•K), and average grain sizes of 67 μm on the surface and 69 μm in the transverse direction.

[0051] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a high thermal conductivity and high formability 6-series anodized aluminum sheet, characterized in that: A high thermal conductivity and high formability 6-series anodized aluminum sheet is prepared by melting, casting, homogenizing, hot rolling, cold rolling, solution quenching, and aging treatment of aluminum ingots and aluminum master alloy ingots. The specific preparation method includes the following steps: (1) According to the alloy composition ratio, aluminum ingots and aluminum intermediate alloy ingots are added to the melting furnace, melted and refined in the temperature range of 720-760℃, slag removed, transferred to the holding furnace, and left to stand for 0.5-4 hours. Then casting begins at a casting temperature of 680-710℃ and a casting speed of 45-60mm / min to cast flat ingots with a thickness of 400-600mm. (2) After milling the flat ingot, put it into a heating furnace and keep it at 530-600℃ for 1-12 hours for homogenization heat treatment. Then cool it down to 400-500℃ for rolling. The hot rolling final thickness is 3-10mm and the final rolling temperature is 250-320℃. (3) The hot-rolled coil is cold-rolled to the finished thickness, with a cold rolling rate of 60-95%; (4) After cold rolling to the finished thickness, solution treatment is carried out at a temperature of 530-580℃ and a holding time of 15-120 seconds. Water cooling or air cooling is used for quenching, followed by aging treatment at a temperature of 150-250℃ and a holding time of 1-24 hours. (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping springback meets the requirements. The chemical composition of the prepared anodized aluminum sheet, by mass fraction, is as follows: Si 0.3~0.5%, Fe 0.08~0.20%, Cu<0.10%, Mn<0.03%, Mg 0.4~0.6%, Ti 0.010~0.025%, with the balance being aluminum and unavoidable impurities.

2. The preparation method according to claim 1, characterized in that: In step (3), cold rolling is divided into two cold rolling processes. The processing rate of the first cold rolling is not less than 40%, and the processing rate of the second cold rolling is 50-70%. Between the two cold rolling processes, an intermediate annealing is carried out at a temperature of 350-485℃ and an annealing time of 30-60s.

3. The preparation method according to claim 1, characterized in that: The characteristics of the finished product obtained in step (5) are: thickness 0.5-2.0mm, tensile strength 180~240MPa, yield strength 150~210MPa, elongation ≥12%, work hardening index n value ≥0.60, plastic strain ratio r value ≥0.23, thermal conductivity λ>200W / (m•K), and average grain size on the surface and in the transverse direction 35~80μm.

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