High-strength and high-thermal-conductivity 6-series aluminum alloy and processing technology thereof

Abstract

The invention relates to the technical field of aluminum alloys, in particular to a high-strength and high-thermal-conductivity 6-series aluminum alloy and a processing technology thereof, and the aluminum alloy comprises the following raw material components in percentage by mass: 0.8-1.0 wt% of Mg, 0.6-0.8 wt% of Si, 0.6-0.8 wt% of Cu, 0.01-0.05 wt% of Sn, less than or equal to 0.01 wt% of Mn, less than or equal to 0.1 wt% of Fe, less than or equal to 0.01 wt% of Cr, less than or equal to 0.02 wt% of Ti, less than or equal to 0.5 wt% of inevitable impurities, and the balance of Al. According to the invention, the content of each element in the aluminum alloy is adjusted, and the aluminum alloy ingot containing the components is subjected to homogenization, extrusion, correction and aging treatment, so that the heat conductivity coefficient of the aluminum alloy profile reaches more than 190W / (m.K), the tensile strength of the aluminum alloy profile is greater than 410Mpa, the yield strength of the aluminum alloy profile is greater than 380Mpa, and the aluminum alloy profile is suitable for high-end application of 6-series aluminum alloys.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a high-strength and high-thermal-conductivity 6-series aluminum alloy and a processing technology thereof. Background Art

[0002] The fifth generation (5G) signal is about to become popular, which puts higher requirements on the thermal conductivity of smartphones. At present, 5G mobile phones generally dissipate heat through heat pipes, fans, graphene patches, thermal adhesives or high thermal conductivity aluminum middle frames. Among them, the aluminum middle frame must not only meet the thermal conductivity requirements, but also have high mechanical properties. 6 series aluminum alloys are widely used in the manufacture of mobile phone components due to their good mechanical properties, processing properties and anode appearance. The commonly used 6 series aluminum alloys have a yield strength of 320 to 360 MPa and a thermal conductivity of less than 150 W / (m·K), which makes it difficult to take into account both high strength and high heat dissipation effects. Therefore, it is increasingly important to improve the thermal conductivity and heat dissipation effect of aluminum alloys to meet the needs of product upgrades. At the same time, it is also necessary to ensure that there is no deformation during profile processing or that the finished product can avoid deformation when used. That is, certain strength and hardness indicators are required under high thermal conductivity conditions. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a high-strength and high-thermal conductivity 6 series aluminum alloy and its processing technology. The 6 series aluminum alloy material has both high thermal conductivity and good mechanical properties, and is suitable for application fields with high requirements on aluminum alloy processing performance.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] First, the present invention provides a high-strength and high-thermal-conductivity 6-series aluminum alloy, which includes the following raw material components, calculated by mass percentage: Mg 0.8-1.0wt.%, Si 0.6-0.8wt.%, Cu 0.6-0.8wt.%, Sn0.01-0.05wt.%, Mn≤0.01wt.%, Fe≤0.1wt.%, Cr≤0.01wt.%, Ti≤0.02wt.%, the total mass of inevitable impurities ≤0.5wt.%, and the balance is Al.

[0006] Furthermore, the high-strength and high-thermal-conductivity 6-series aluminum alloy has a yield strength of ≥380 MPa, a tensile strength of ≥410 MPa, and a thermal conductivity of ≥190 W / (mK).

[0007] Secondly, the present invention provides a processing technology for the above-mentioned high-strength and high-thermal-conductivity 6-series aluminum alloy, comprising the following steps:

[0008] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0009] The ingot with the above composition is homogenized, kept at 560-580°C for 16-30h, and then air-cooled to room temperature;

[0010] The homogenized material is extruded, the extrusion rod temperature is 520-580°C, the extrusion speed is 10-15 m / min, and the outlet temperature is 530-550°C;

[0011] Correct the cooled extruded material by 5 to 10%;

[0012] The extruded material is subjected to aging treatment, first at 185-200°C for 4-10 hours, then at 230-250°C for 10-60 seconds, and then at 160-180°C for 8-20 hours. The size of the strengthening phase Mg2Si in the aged material is 1-1.8 nm.

[0013] In the 6 series aluminum alloy of the present invention, Mg, Si, and Cu are the main added elements, and their content levels determine the mechanical properties of the material. The greater the addition amount, the higher the strength. However, if the content is too high, the lattice distortion will be caused by a large amount of solutes, resulting in a decrease in thermal conductivity. In general: Mg 0.8-1.0wt.%, Si 0.6-0.8wt.%, Cu 0.6-0.8wt.%, can ensure that the material has a higher strength and thermal conductivity.

[0014] Mn, Fe, Cr, and Ti are impurity elements that greatly reduce the thermal conductivity of the material. Therefore, their content must be limited and ensure that the material cost is not increased on a large scale, such as Mn≤0.01wt.%, Fe≤0.1wt.%, Cr≤0.01wt.%, and Ti≤0.02wt.%.

[0015] The 6 series aluminum alloy of the present invention contains a small amount of Sn (0.01-0.05 wt.%), which can promote the precipitation of solutes in the matrix and thus significantly improve the thermal conductivity of the material. However, if the content is too much, the thermal conductivity will be reduced.

[0016] The ingots of the above composition are homogenized, kept at 560-580℃ for 16-30h, and then air-cooled to room temperature, and the composition is uniformed and stress is eliminated by homogenization; the homogenized material is extruded, the extrusion rod temperature is 520-580℃, and the outlet temperature is 530-550℃. Extrusion is used to form and provide a structural basis for subsequent aging. The extruded material is straightened by 5-10% deformation, which is crucial for improving thermal conductivity and mechanical properties. Vacancies and dislocations are formed by deformation, which promotes the precipitation of strengthening phases during the aging process and can simultaneously improve strength and thermal conductivity; the extruded material is aged: 185-200℃ for 4-10h, then 230-250℃ for 10-60s, and then 160-180℃ for 8-20h. Through three-level aging treatment, the size of the structural strengthening phase is regulated, so that the material has both high strength and high thermal conductivity.

[0017] The present invention adjusts the content of each element in the 6-series aluminum alloy and controls the process so that the material obtains higher strength and better thermal conductivity, and is suitable for high-end applications of the 6-series aluminum alloy. DETAILED DESCRIPTION

[0018] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0019] Example 1

[0020] The high-strength and high-thermal-conductivity 6 series aluminum alloy comprises, by mass percentage, Mg 0.8wt.%, Si 0.8wt.%, Cu0.8wt.%, Mn 0.003wt.%, Fe 0.08wt.%, Cr 0.005wt.%, Ti 0.003wt.%, Sn 0.01wt.%, the total mass of unavoidable impurities ≤0.5wt.%, and the balance is Al.

[0021] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0022] The ingot was homogenized, kept at 560°C for 30 h, and then air-cooled to room temperature;

[0023] The homogenized material was extruded, with an extrusion rod temperature of 580°C, an extrusion speed of 13 m / min, and an outlet temperature of 550°C;

[0024] Apply 10% deformation straightening to the cooled extruded material;

[0025] The extruded material was subjected to aging treatment: first at 185°C for 10 h, then at 230°C for 60 seconds, and then at 160°C for 20 h.

[0026] Example 2

[0027] The high-strength and high-thermal-conductivity 6 series aluminum alloy comprises, by mass percentage, Mg 1.0wt.%, Si 0.6wt.%, Cu0.6wt.%, Mn 0.005wt.%, Fe 0.07wt.%, Cr 0.004wt.%, Ti 0.002wt.%, Sn0.05wt.%, the total mass of unavoidable impurities ≤0.5wt.%, and the balance is Al.

[0028] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0029] The ingot was homogenized, kept at 580°C for 16 h, and then air-cooled to room temperature;

[0030] The homogenized material was extruded, with an extrusion rod temperature of 520°C, an extrusion speed of 13 m / min, and an outlet temperature of 530°C;

[0031] Apply 5% deformation straightening to the cooled extruded material;

[0032] The extruded material was subjected to aging treatment: first at 200°C for 4 h, then at 250°C for 10 seconds, and then at 180°C for 20 h.

[0033] Example 3

[0034] The high-strength and high-thermal-conductivity 6 series aluminum alloy comprises, by mass percentage, Mg 0.9wt.%, Si 0.7wt.%, Cu0.75wt.%, Mn 0.005wt.%, Fe 0.08wt.%, Cr 0.006wt.%, Ti 0.01wt.%, Sn0.04wt.%, the total mass of unavoidable impurities ≤0.5wt.%, and the balance is Al.

[0035] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0036] The ingot was homogenized, kept at 570°C for 20 h, and then air-cooled to room temperature;

[0037] The homogenized material was extruded, with an extrusion rod temperature of 560°C, an extrusion speed of 13 m / min, and an outlet temperature of 542°C;

[0038] Apply 9% deformation straightening to the cooled extruded material;

[0039] The extruded material was subjected to aging treatment: first at 190°C for 5 h, then at 240°C for 26 seconds, and then at 170°C for 18 h.

[0040] Comparative Example 1

[0041] The aluminum alloy includes, by mass percentage, Mg 0.96wt.%, Si 0.92wt.%, Cu 0.8wt.%, Mn 0.8wt.%, Fe 0.08wt.%, Cr 0.7wt.%, Ti 0.07wt.%, the total mass of inevitable impurities ≤0.5wt.%, and the balance is Al.

[0042] The processing technology of the aluminum alloy in Comparative Example 1 is consistent with that in Example 1.

[0043] Comparative Example 2

[0044] The composition of the aluminum alloy in Comparative Example 2 is consistent with that in Example 1, except that:

[0045] The ingot was homogenized, kept at 570°C for 20 h, and then air-cooled to room temperature;

[0046] The homogenized material was extruded, with an extrusion rod temperature of 560°C, an extrusion speed of 13 m / min, and an outlet temperature of 542°C;

[0047] The extruded material was subjected to aging treatment: 190°C for 5 h, then 240°C for 26 seconds, and then 170°C for 18 h.

[0048] Comparative Example 3

[0049] The composition of the aluminum alloy in Comparative Example 3 is consistent with that in Example 1, except that:

[0050] The ingot was homogenized, kept at 560°C for 30 h, and then air-cooled to room temperature;

[0051] The homogenized material was extruded, with an extrusion rod temperature of 580°C, an extrusion speed of 13 m / min, and an outlet temperature of 550°C;

[0052] Straightening of extruded materials with 10% deformation;

[0053] Aging treatment of extruded materials: keep at 200℃ for 20h.

[0054] According to the standard GB / T6892-2015 "General Industrial Aluminum and Aluminum Alloy Extrusion Profiles", the performance of each aluminum alloy in Examples 1 to 3 and Comparative Examples 1 to 3 was tested. Table 1 shows the performance and microstructure characteristics of the aluminum alloy in Examples 1-3 and Comparative Examples 1-3.

[0055] Table 1

[0056]

[0057] Among them, the greater the yield strength, the better the performance of the aluminum alloy in resisting the stress of micro plastic deformation, and the better the performance of the aluminum alloy. The greater the tensile strength, the better the fracture resistance of the aluminum alloy, and the better the performance of the aluminum alloy. The smaller the plasticity, the greater the minimum force required for permanent deformation of the aluminum alloy, and the better the performance of the aluminum alloy. The thermal conductivity of the aluminum alloy profile produced by the processing technology of the present invention can reach more than 190W / (mK), while its tensile strength reaches more than 410Mpa, and its yield strength reaches more than 380Mpa, which is much greater than the mechanical properties of pure aluminum. These mechanical performance indicators enable it to be used in many shell products or product fields that need to be deeply processed. Unlike pure aluminum, which cannot be used as a shell or for processing because of its low strength, it has good thermal conductivity, can greatly accelerate the heat dissipation of equipment, and has great application value.

[0058] The present invention reasonably adjusts the content of each element in the aluminum alloy and the processing technology so that the material has both high strength and thermal conductivity, and is suitable for fields with higher requirements for strength and thermal conductivity.

[0059] According to the disclosure of the above description, those skilled in the art to which the present invention belongs may also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A high-strength and high-thermal-conductivity 6-series aluminum alloy, characterized in that: Calculated by mass percentage, the raw material components include: Mg 0.8-1.0wt.%, Si 0.6-0.8wt.%, Cu 0.6-0.8wt.%, Sn 0.01-0.05wt.%, Mn≤0.01wt.%, Fe≤0.1wt.%, Cr≤0.01wt.%, Ti≤0.02wt.%, the total mass of inevitable impurities ≤0.5wt.%, and the balance is Al.

2. The high-strength and high-thermal-conductivity 6-series aluminum alloy according to claim 1, characterized in that: The yield strength of the high-strength and high-thermal-conductivity 6-series aluminum alloy is ≥380MPa.

3. The high-strength and high-thermal-conductivity 6-series aluminum alloy according to claim 1, characterized in that: The tensile strength of the high-strength and high-thermal-conductivity 6-series aluminum alloy is ≥410MPa.

4. The high-strength and high-thermal-conductivity 6-series aluminum alloy according to claim 1, characterized in that: The thermal conductivity of the high-strength and high-thermal-conductivity 6-series aluminum alloy is ≥190W / (mK).

5. A processing technology for the high-strength and high-thermal-conductivity 6-series aluminum alloy according to any one of claims 1 to 4, characterized in that: The steps include: Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot; The ingot with the above composition is homogenized, kept at 560-580°C for 16-30h, and then air-cooled to room temperature; The homogenized material is extruded, the extrusion rod temperature is 520-580°C, and the outlet temperature is 530-550°C; Correct the cooled extruded material by 5 to 10%; The extruded material is subjected to aging treatment, first at 185-200°C for 4-10 hours, then at 230-250°C for 10-60 seconds, and then at 160-180°C for 8-20 hours.

6. The processing technology of high-strength and high-thermal-conductivity 6-series aluminum alloy according to claim 5 is characterized in that: The size of the strengthening phase Mg2Si in the aged material is 1 to 1.8 nm.

7. The processing technology of high-strength and high-thermal-conductivity 6-series aluminum alloy according to claim 5 is characterized in that: During the extrusion process, the extrusion speed is 10 to 15 m / min.

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