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

Abstract

The invention discloses a preparation method of a high-thermal-conductivity and high-forming 6-series anodized aluminum oxide sheet. The aluminum alloy comprises the following chemical components in percentage by mass: 0.3 to 0.5 percent of Si, 0.08 to 0.20 percent of Fe, less than 0.10 percent of Cu, less than 0.03 percent of Mn, 0.4 to 0.6 percent of Mg, 0.010 to 0.025 percent of Ti and the balance of aluminum and inevitable impurities. According to the aluminum alloy sheet with the thickness of 0.5 mm to 2.0 mm, the tensile strength is 180 MPa to 240 MPa, the yield strength is 150 MPa to 210 MPa, the ductility is larger than or equal to 12%, the work hardening index n value is larger than or equal to 0.60, the plastic strain ratio r value is larger than or equal to 0.23, the surface and transverse average grain size is 35 micrometers to 80 micrometers, and the heat conductivity is larger than 200 W / (mK).

Description

Technical Field

[0001] The invention belongs to the field of preparation of aluminum alloy strips, and specifically relates to a method for preparing a high-thermal-conductivity and high-formability 6-series anodized aluminum sheet. Background Art

[0002] At present, the anodized materials used for laptop shells are mostly stamped from 5-series aluminum alloy sheets, or made from 6-series aluminum profiles after CNC processing. The 5-series aluminum alloy sheets have good forming properties, but low thermal conductivity. Although the 6-series aluminum profiles have good performance in various aspects, they are expensive and have low effective material utilization. At present, the 6-series aluminum alloy sheets generally have poor forming properties and cannot meet the forming requirements of laptop shells, and are prone to cracking and other problems. With the popularity of AI computers, the heat dissipation requirements of AI chips have been significantly improved. The traditional 5-series aluminum alloy cannot meet the high power and high heat dissipation requirements of AI chips. Therefore, it is urgent to develop a 6-series aluminum alloy sheet with high thermal conductivity and high formability for use in laptop shells.

[0003] The patent application with the patent application number 201911372828.9 discloses a high-conductivity 6-series aluminum alloy material and its production process. It is obtained by adding additional elements B 0.015-0.02%, Gd 0.15-0.18%, low-temperature 450-500℃ homogenization treatment, and double-stage aging at 175℃×9h+220℃×3h after extrusion. Its composition design and preparation method are also different.

[0004] The patent application with patent application number 201811260377.5 discloses a T6 state aluminum alloy conductive pipe and a preparation method thereof, which are proportioned according to the alloy composition of 6101, namely Si0.38%-0.40%, Fe0.05%-0.10%, Cu0.05%-0.08%, Mn<0.01%, Mg0.54%-0.56%, Cr<0.01%, Zn<0.02%, Ti0.02%-0.04%, Mg / Si=1.34-1.48, other single elements ≤0.05%, and other impurity elements ≤0.15% in total. The cast rod is homogenized, extruded, online quenched, stretched and straightened, and subjected to two-stage artificial aging in sequence to obtain a T6 state aluminum alloy conductive pipe, which has high purity of alloy composition and different preparation methods.

[0005] Patent application No. 201810889362.9 discloses a 6-series alloy anodized aluminum plate strip for mobile phone frames and its preparation method. By limiting the element Fe≤0.08, and performing a two-stage homogenization treatment at 390~410℃, 8~12 hours and 530~540℃, 30~40 hours, hot rolling to a thickness of 4.0~10.0mm, and then undergoing a long-term solid solution and aging treatment at 540~570℃, 1~2 hours, an aluminum alloy thick plate is finally obtained. However, low impurity elements cannot add a high proportion of recycled aluminum, and its application is limited to thick plates on mobile phone frames.

[0006] Patent application No. 202110816103.5 discloses a high-strength anodized aluminum sheet and its preparation method. After the ingot is homogenized and heat treated (540~560℃ / 3~8 hours + 500~510℃ / 1~6 hours), the hot rolling final rolling temperature is adjusted to 360~400℃ and no intermediate annealing is performed. After cold rolling, the finished product is directly subjected to 500~520℃ low-temperature solid solution and 150~200℃ / 5~24h artificial aging treatment. This method uses the high temperature precipitation of a large number of second phases in the hot-rolled material to increase the recrystallization nucleation points in the solid solution process and refine the grains. Its disadvantage is that the high-temperature rolling at 500~510℃ after homogenization is likely to cause abnormal recrystallization in the hot rolling stage, and the hot rolling final rolling temperature of 360~400℃ is likely to cause a large amount of Mg2Si to be unevenly precipitated, resulting in the finished product showing anode heterochromatic line defects, and its forming performance cannot meet the forming of various shell parts of the laptop computer. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability to achieve excellent performance in view of the shortcomings of the prior art.

[0008] To achieve the purpose of the present invention, the following technical scheme is adopted: 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 is as follows by mass fraction: Si 0.3-0.5%, Fe 0.08-0.20%, Cu<0.10%, Mn<0.03%, Mg 0.4-0.6%, Ti0.010-0.025%, and the remainder is aluminum and unavoidable impurities.

[0009] A method for preparing a high thermal conductivity and high formability 6 series anodized aluminum sheet: a high thermal conductivity and high formability 6 series anodized aluminum sheet is prepared through smelting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and straightening. The specific preparation method includes the following steps: (1) According to the alloy composition ratio, various raw materials such as aluminum ingots and aluminum master alloy ingots are added to the smelting furnace, melted, refined, slag removed, and transferred from the converter to the holding furnace at a temperature range of 720-760°C. The furnace is left to stand for 0.5-4 hours, and then casting is started. The casting temperature is 680-710°C, the casting speed is 45-60mm / min, and the ingot is cast into a slab with a thickness of 400-600mm. (2) After the flat ingot is milled, it is placed in a heating furnace and kept at 530-600°C for 1-12 hours for homogenization heat treatment, and then the temperature is lowered to 400-500°C for rolling. The final hot rolling thickness is 3-10 mm and the final rolling temperature is 250-320°C; (3) Cold rolling the hot rolled coil to the finished thickness, with a cold rolling rate of 60-95%, and then solution treatment. The cold rolling process can also be divided into two cold rolling processes, with the first cold rolling rate being no less than 40%, the second cold rolling rate being 50-70%, and an intermediate annealing being performed between the two cold rolling processes, with an annealing temperature of 350-485°C and an annealing time of 30-60s; (4) After cold rolling to the finished thickness, solution treatment is carried out at a temperature of 530-580°C and a holding time of 15-120 seconds. Water cooling or air cooling quenching is adopted, and then aging treatment is carried out at a temperature of 150-250°C and a holding time of 1-24 hours.

[0010] (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping rebound can meet the requirements. The characteristics of the finished product 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), surface and lateral average grain size 35~80μm. It has good forming performance and can be used for the forming of various shells of laptop computers.

[0011] The beneficial effects of the present invention are: The present invention is based on the combination of forming, thermal conductivity, anodizing and other properties of 6 series materials, coordinates and regulates the composition, grain and organization of the materials, reasonably designs high-temperature homogenization at 530-600°C to eliminate dendrite segregation and reduce the resistance to electron movement, and low-temperature intermediate annealing at 350-485°C to avoid a large amount of Mg2Si dissolution, and combines the cold rolling processing rate and high-temperature solid solution at 530-580°C to obtain a moderate grain size, reduce the increase in the probability of scattering in the electron transmission process and the decrease in thermal conductivity due to excessive grain boundaries, and finally obtains a product with a thickness of 0.5-2.0mm, a tensile strength of 180-240MPa, a yield strength of 150-210MPa, an elongation of ≥12%, a work hardening index n value of ≥0.60, a plastic strain ratio r value of ≥0.23, a thermal conductivity λ>200W / (m•K), and a surface and lateral average grain size of 35-80μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a sample image prepared in Example 1 of the present invention.

[0013] Figure 2 This is a sample image prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to these embodiments.

[0015] The present invention aims to provide a high thermal conductivity and high formability 6 series anodized aluminum sheet, the mass fractions of the components involved are: 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 is aluminum and unavoidable impurities.

[0016] A high thermal conductivity and high formability 6 series anodized aluminum sheet is obtained through hot rolling, cold rolling, solution quenching, aging and straightening.

[0017] During the melting and pouring process, the solidification cooling speed is fast, so the atoms in the liquid phase have no time to diffuse, resulting in unbalanced crystallization. Dendrite segregation will also affect the probability of electron scattering, increase the resistance of electron movement, and reduce thermal conductivity. Therefore, it is very necessary to heat treat the cast alloy. By high-temperature homogenization at 530-600℃ for 1-12 hours, the microsegregation can be effectively improved, and then the temperature is lowered to 400-500℃ for rolling, which can avoid abnormal grain growth during hot rolling.

[0018] Under large deformation cold rolling conditions, Mg2Si gradually precipitates. Through low-temperature intermediate annealing at 350-485℃, on the one hand, the equiaxicity of the grains is improved, and more importantly, a large amount of Mg2Si is avoided from dissolving back.

[0019] By controlling the cold rolling processing rate to 60~95% and high-temperature solid solution at 530-580℃, the appropriate grain size is obtained, the increased probability of scattering in the electron transmission process and the decrease in thermal conductivity caused by excessive grain boundaries are reduced, and the forming performance is also guaranteed.

[0020] The following is an explanation with a specific implementation example.

[0021] Example 1 A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability: The chemical composition of the aluminum alloy sheet and strip is calculated by mass fraction as follows: Si 0.32%, Fe 0.15%, Cu0.02%, Mn 0.02%, Mg 0.45%, Ti 0.015%, and the balance is aluminum and unavoidable impurities. A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability: A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability is obtained through smelting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and straightening. The specific preparation method includes the following steps: (1) According to the alloy composition ratio, various raw materials such as aluminum ingots and aluminum master alloy ingots are added to the melting furnace, melted, refined, slag removed, and transferred from the converter to the holding furnace at a temperature range of 725°C. The furnace is left to stand for 2 hours, and then casting is started. The casting temperature is 710°C, the casting speed is 52mm / min, and the ingot is cast into a 600mm thick flat ingot; (2) After the flat ingot is milled, it is placed in a heating furnace and kept at 570°C for 12 hours for homogenization heat treatment, and then the temperature is lowered to 420°C for rolling. The final hot rolling thickness is 5 mm and the final rolling temperature is 250°C. (3) The hot rolled coil is cold rolled to a finished thickness of 2 mm with a cold rolling rate of 60%, and then solution treated.

[0022] (4) After cold rolling to the finished thickness, the steel is solution treated at 560°C for 60 seconds, water cooled, and then aged at 180°C for 10 hours.

[0023] (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping rebound can meet the requirements.

[0024] The aluminum alloy thin plate prepared by the present 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 value of 0.68, a plastic strain ratio r value of 0.26, a thermal conductivity λ=220 W / (m•K), and surface and lateral average grain sizes of 70 and 72 μm respectively.

[0025] Example 2 A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability: The chemical composition of the aluminum alloy sheet and strip is calculated by mass fraction as follows: Si 0.38%, Fe 0.20%, Cu 0.015%, Mn 0.014%, Mg 0.46%, Ti 0.015%, and the balance is aluminum and unavoidable impurities. A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability: A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability is obtained through smelting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and straightening. The specific preparation method includes the following steps: (1) According to the alloy composition ratio, various raw materials such as aluminum ingots and aluminum master alloy ingots are added to the smelting furnace, melted, refined, slag removed, and transferred from the converter to the holding furnace at a temperature range of 760°C. The furnace is left to stand for 1 hour, and then casting is started. The casting temperature is 700°C, the casting speed is 55mm / min, and the ingot is cast into a 500mm thick flat ingot; (2) After the flat ingot is milled, it is placed in a heating furnace and kept at 580°C for 5 hours for homogenization heat treatment, and then the temperature is lowered to 450°C for rolling. The final hot rolling thickness is 7 mm and the final rolling temperature is 265°C. (3) cold rolling the hot rolled coil to 4 mm, and then cold rolling to the finished product thickness of 1.2 mm, the first cold rolling processing rate is 42.86%, the second cold rolling processing rate is 70%, and an intermediate annealing at 350°C / 60 seconds is performed between the two cold rollings; (4) After cold rolling to the finished thickness, solution treatment is carried out at a solution temperature of 570°C and a holding time of 30 seconds. Air cooling quenching is adopted, and then aging treatment is carried out at a treatment temperature of 150°C and a holding time of 20 hours.

[0026] (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping rebound can meet the requirements.

[0027] The aluminum alloy thin plate prepared by the present 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 value of 0.72, a plastic strain ratio r value of 0.25, a thermal conductivity λ215 W / (m•K), and surface and lateral average grain sizes of 74 and 78 μm respectively.

[0028] Example 3 A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability: The chemical composition of the aluminum alloy sheet and strip is calculated by mass fraction as follows: Si 0.40%, Fe 0.18%, Cu 0.001%, Mn 0.001%, Mg 0.60%, Ti 0.025%, and the balance is aluminum and unavoidable impurities. A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability: A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability is obtained through smelting, casting, homogenization, hot rolling, cold rolling, solution quenching, artificial aging, and straightening. The specific preparation method includes the following steps: (1) According to the alloy composition ratio, various raw materials such as aluminum ingots and aluminum master alloy ingots are added to the smelting furnace, melted, refined, slag removed, and transferred from the converter to the holding furnace at a temperature range of 740°C. The furnace is left to stand for 4 hours, and then casting is started. The casting temperature is 705°C, the casting speed is 60mm / min, and the ingot is cast into a 600mm thick flat ingot; (2) After the flat ingot is milled, it is placed in a heating furnace and kept at 600°C for 2 hours for homogenization heat treatment, and then the temperature is lowered to 500°C for rolling. The final hot rolling thickness is 10 mm and the final rolling temperature is 260°C. (3) cold rolling the hot rolled coil to 5.0 mm, and then cold rolling to the finished product thickness of 1.5 mm, with the first cold rolling processing rate of 50%, the second cold rolling processing rate of 70%, and an intermediate annealing at 420°C / 30 seconds between the two cold rollings; (4) After cold rolling to the finished thickness, solution treatment is carried out at a solution temperature of 580°C and a holding time of 15 seconds. Air cooling quenching is adopted, and then aging treatment is carried out at a treatment temperature of 200°C and a holding time of 2 hours.

[0029] (5) After aging treatment, the plate is straightened to obtain a good plate shape, eliminate internal stress, and ensure that the stamping rebound can meet the requirements.

[0030] The aluminum alloy thin plate prepared by the present 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 value of 0.66, a plastic strain ratio r value of 0.23, a thermal conductivity λ208 W / (m•K), and surface and lateral average grain sizes of 67 and 69 μm respectively.

[0031] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a 6-series anodized aluminum sheet with high thermal conductivity and high formability, characterized in that: Aluminum ingots and aluminum master alloy ingots are subjected to smelting, casting, homogenization, hot rolling, cold rolling, solution quenching, and aging treatment to obtain a high thermal conductivity and high formability 6 series anodized aluminum sheet. The specific preparation method includes the following steps: (1) According to the alloy composition ratio, aluminum ingots and aluminum master alloy ingots are added to the smelting furnace, melted at a temperature range of 720-760°C, refined, slag removed, and transferred from the converter to the holding furnace. The furnace is left to stand for 0.5-4 hours, and then casting is started. The casting temperature is 680-710°C, the casting speed is 45-60mm / min, and the ingot is cast into a slab with a thickness of 400-600mm. (2) After the flat ingot is milled, it is placed in a heating furnace and kept at 530-600°C for 1-12 hours for homogenization heat treatment, and then the temperature is lowered to 400-500°C for rolling. The final hot rolling thickness is 3-10 mm and the final rolling temperature is 250-320°C; (3) Cold rolling the hot rolled coil 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°C and a holding time of 15-120 seconds. Water cooling or air cooling quenching is adopted, and then aging treatment is carried out at a temperature of 150-250°C 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 rebound can meet the requirements.

2. The preparation method according to claim 1, characterized in that: In step (3), the cold rolling is divided into two cold rollings, the first cold rolling processing rate is not less than 40%, the second cold rolling processing rate is 50-70%, and an intermediate annealing is performed between the two cold rollings, the annealing temperature is 350-485°C, and the annealing time is 30-60s.

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

4. The preparation method according to claim 1, characterized in that: The chemical composition of the prepared aluminum alloy sheet and strip is as follows by mass fraction: Si 0.3~0.5%, Fe 0.08~0.20%, Cu<0.10%, Mn<0.03%, Mg 0.4~0.6%, Ti0.010~0.025%, and the balance is aluminum and unavoidable impurities.

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