6-series aluminum alloy for stamping back plate and processing technology of 6-series aluminum alloy

Abstract

The invention relates to the technical field of aluminum alloys, in particular to a 6-series aluminum alloy for a stamping backboard and a processing technology of the 6-series aluminum alloy, and the aluminum alloy comprises the following raw material components in percentage by mass: 0.9-1.5 wt.% of Mg, 0.5-0.7 wt.% of Si, 0.6-0.8 wt.% of Cu, 0.03-0.08 wt.% of Mn, less than or equal to 0.02 wt.% of Cr, less than or equal to 0.05 wt.% of Ti, less than or equal to 0.10 wt.% of Fe and the balance of Al and inevitable impurities. By adjusting the content of each element in the aluminum alloy and sequentially performing homogenization, extrusion, stamping, regression treatment and aging treatment on the aluminum alloy cast ingot containing the components, the 6-series aluminum alloy profile has higher strength and formability, and is suitable for the field of aluminum alloy back plate stamping.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a 6 series aluminum alloy for a stamping back plate and a processing technology thereof. Background Art

[0002] Aluminum alloys are used in the manufacture of mobile phone middle frames or back panels due to their medium strength and good anode appearance. In the 4G era, aluminum alloys were mainly used in the manufacture of back panels. Entering 5G, due to the complexity of mobile phone signals, aluminum alloy back panels have a strong shielding effect on signals, so aluminum alloys are used in the form of middle frames. With the solution of the problem of 5G signal shielding on the back panel of the mobile phone, aluminum alloys are once again applied to smartphones in the form of back panels. The earliest aluminum alloy back panel was applied in the form of 6063 aluminum alloy full CNC, but under the guidance of the trend of cost reduction, the market needs to apply it in the form of stamping 6063 and other aluminum alloy thin plates, so there is a high demand for the stamping performance of aluminum alloys. Usually 6063 is provided in the form of T4 state, at which time the material has a higher formability. After stamping and forming in the mobile phone foundry, it is aged. In the application process of 6013 aluminum alloy, the material must be annealed after extrusion to obtain greater plasticity, and then stamped, solution treated and aged in the foundry. However, the composition of 6013 aluminum alloys for mobile phones has been adjusted individually. For example, the content of Mn and Cr elements is low, and the material is prone to recrystallization and coarse grains during the solid solution process; the temperature of the solid solution treatment is lower than the normal production temperature of the aluminum plant, and the quenching speed is slow to avoid large internal stress, etc. This results in the frequent occurrence of poor anode (spotting), poor stamping (poor plasticity), insufficient mechanical properties (unsuitable quenching strength or quenching temperature) and other phenomena during the application of 6013 aluminum alloys, which restricts the application of the material. Therefore, it is necessary to provide a high-strength aluminum alloy suitable for stamping mobile phone back panels and its processing technology. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a 6 series aluminum alloy for stamping back panels and a processing technology thereof, so that the 6 series aluminum alloy material has higher strength and forming performance, and is suitable for the field of high-strength aluminum alloys for stamping mobile phone back panels.

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

[0005] First, the present invention provides a 6 series aluminum alloy for a stamping back plate, which includes the following raw material components in mass percentage: Mg 0.9-1.5wt.%, Si 0.5-0.7wt.%, Cu 0.6-0.8wt.%, Mn 0.03-0.08wt.%, Cr≤0.02wt.%, Ti≤0.05wt.%, Fe≤0.10wt.%, and the balance is Al and unavoidable impurities.

[0006] Furthermore, the mass ratio of Mg to Si in the raw material composition of the 6-series aluminum alloy for the stamping back plate is (2-3):1.

[0007] First, the present invention provides a processing technology for a 6 series aluminum alloy for a stamping back plate, which specifically includes 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 540-580°C for 16-20h, and then air-cooled to room temperature;

[0010] The homogenized material is extruded, the extrusion rod temperature is 520-550°C, the outlet temperature is 500-530°C, and the extrusion speed is 0.3-1 m / min;

[0011] The extruded material is punched and then subjected to a return treatment, and kept at 300-350°C for 2-30 seconds;

[0012] The extruded material was artificially aged at 185°C for 9 hours.

[0013] Furthermore, in the extruded state, the number of the strengthening phase Mg2Si with a size less than 1 μm is ≥ 6*10 6 Pieces / mm 2 .

[0014] Furthermore, in the aged state, the yield strength of the aluminum alloy is greater than 310 MPa and the tensile strength is greater than 350 MPa.

[0015] The beneficial effects of the present invention are:

[0016] The stamping performance of 6 series (Al-Mg-Si-Cu) aluminum alloy is generally worse than that of 5 series (Al-Mg) aluminum alloy. This is because the Mg element has a positive effect on the stamping performance of the material, such as the n value. However, the Mg content should not be too much, otherwise the aging strengthening effect of the material is poor, and its content Mg 0.9~1.5wt.% is appropriate; at the same time, the material must contain a certain amount of Si element to provide the basis for the formation of the strengthening phase Mg2Si, and its content needs to be lower than Mg, such as 0.5~0.7wt.%, so that the material can have better stamping performance while ensuring that there is enough Mg in the matrix. Furthermore, Mg / Si=2-3, the stamping performance is better, but the strength performance will be slightly reduced; the Cu element plays a role in solid solution strengthening and aging strengthening in the 6 series aluminum alloy, and its content is preferably 0.6~0.8wt.%.

[0017] Mn is a trace element, which mainly controls the grain size, but it should not be too much, otherwise fiber crystals will appear in the material, which will cause anode material lines. Too little content will cause the corrosion resistance of the material to decrease. Its content is preferably 0.03-0.08wt.%. Ti mainly plays the role of refining the cast grains, and Ti≤0.05wt.% is sufficient.

[0018] Cr and Fe are trace impurity elements, as long as they are controlled within the required range: Cr≤0.02wt.%, Fe≤0.10wt.%.

[0019] The processing technology of the above aluminum alloy is as follows: the ingots of the above composition are homogenized, kept at 540-580℃ for 16-20h, and then air-cooled to room temperature. Dissolve the coarse Mg2Si phase during the homogenization process; extrude the homogenized material, the extrusion rod temperature is 520-550℃, and the extrusion speed is 0.3-1 m / min. The high temperature is to continue to dissolve the undissolved Mg2Si during the homogenization process, and the extrusion speed is controlled. Slow extrusion is used to precipitate Mg2Si during the extrusion process, so that the material HV is low and is conducive to subsequent stamping; the extruded material is stamped, and then the regression treatment is carried out at 300-350℃ for 2-30 seconds. This process is to dissolve the Mg2Si phase formed during the slow extrusion process, so that the material has aging-strengthening properties; then the aging treatment is carried out at 185℃ for 9h. It is worth noting that if T4 state extrusion is used, subsequent stamping will cause cracking. If O-state aluminum is used for stamping, high-temperature solution treatment must be added later, which will cause coarse grains and form anode spots. If T4 aluminum is used for high-temperature regression, it is easy to cause cracking after stamping.

[0020] The present invention reasonably adjusts the content of each element in the aluminum alloy and the processing technology, so that the 6 series aluminum alloy material has higher strength and forming performance, and is suitable for the aluminum alloy back plate stamping field. DETAILED DESCRIPTION

[0021] 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.

[0022] Example 1

[0023] A 6 series aluminum alloy for a stamping back plate, comprising, by mass percentage, Mg 1.4wt.%, Si 0.6wt.%, Cu 0.8wt.%, Mn 0.03wt.%, Cr 0.01wt.%, Ti 0.02wt.%, Fe 0.09wt.%, and the balance being Al and unavoidable impurities;

[0024] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0025] The ingot of the above composition is homogenized, kept at 540°C for 20 hours, and then air-cooled to room temperature;

[0026] The homogenized material was extruded at a rod temperature of 550°C, an extrusion speed of 0.3 m / min, and an outlet temperature of 530°C;

[0027] The extruded material was stamped, then subjected to a regression treatment at 300°C for 30 seconds, and then subjected to an artificial aging treatment at 185°C for 9 hours.

[0028] Example 2

[0029] A 6 series aluminum alloy for a stamping back plate, comprising, by mass percentage: Mg 1.5wt.%, Si 0.5wt.%, Cu 0.6wt.%, Mn 0.08wt.%, Cr 0.008wt.%, Ti 0.009wt.%, Fe 0.08wt.%, and the balance being Al and unavoidable impurities;

[0030] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0031] The ingot of the above composition was homogenized, kept at 580°C for 16 hours, and then air-cooled to room temperature;

[0032] The homogenized material is extruded, with an extrusion rod temperature of 520°C, an extrusion speed of 1 m / min, and an outlet temperature of 500°C;

[0033] The extruded material was stamped, then subjected to a regression treatment at 350°C for 2 seconds, and then subjected to an artificial aging treatment at 185°C for 9 hours.

[0034] Example 3

[0035] A 6 series aluminum alloy for a stamping back plate, comprising, by mass percentage, Mg 1.3wt.%, Si 0.63wt.%, Cu 0.75wt.%, Mn 0.06wt.%, Cr 0.009wt.%, Ti 0.007wt.%, Fe 0.008wt.%, and the balance being Al and unavoidable impurities;

[0036] Weigh raw materials according to the mass percentage of each element in the aluminum alloy, and perform smelting and casting to obtain an ingot;

[0037] The ingot of the above composition was homogenized, kept at 565°C for 18 hours, and then air-cooled to room temperature;

[0038] The homogenized material was extruded, with an extrusion rod temperature of 540°C, an extrusion speed of 0.8 m / min, and an outlet temperature of 510°C;

[0039] The extruded material was stamped, then subjected to a regression treatment at 320°C for 15 seconds, and then subjected to an artificial aging treatment at 185°C for 9 hours.

[0040] Comparative Example 1

[0041] The aluminum alloy composition in Comparative Example 1 is consistent with that in Example 1, except that:

[0042] The ingot of the above composition is homogenized, kept at 540°C for 20 hours, and then air-cooled to room temperature;

[0043] The homogenized material was extruded, with an extrusion rod temperature of 550°C, an extrusion speed of 6 m / min, and an outlet temperature of 530°C;

[0044] The extruded material was stamped, then subjected to a regression treatment at 300°C for 30 seconds, and then subjected to an artificial aging treatment at 185°C for 9 hours.

[0045] Comparative Example 2

[0046] The aluminum alloy comprises, by mass percentage, Mg 0.5wt.%, Si 1.2wt.%, Cu 0.68wt.%, Mn 0.09wt.%, Cr 0.01wt.%, Ti 0.02wt.%, Fe 0.09wt.%, and the balance is Al and unavoidable impurities;

[0047] The processing technology of Comparative Example 2 is consistent with that of Example 1.

[0048] Comparative Example 3

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

[0050] The ingot of the above composition is homogenized, kept at 540°C for 20 hours, and then air-cooled to room temperature;

[0051] The homogenized material was extruded at a rod temperature of 550°C, an extrusion speed of 0.3 m / min, and an outlet temperature of 530°C;

[0052] The extruded material was artificially aged at 185°C for 9 h, then the material was stamped and then subjected to regression treatment at 300°C for 30 seconds.

[0053] According to GB / T6892-2023 "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.

[0054] Table 1

[0055]

[0056] The present invention reasonably adjusts the content of each element in the aluminum alloy and the processing technology, so that the 6 series aluminum alloy material has higher strength and forming performance, and is suitable for the aluminum alloy back plate stamping field.

[0057] 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 6 series aluminum alloy for stamping back plate, characterized in that: Calculated by mass percentage, the raw material components include: Mg 0.9-1.5wt.%, Si 0.5-0.7wt.%, Cu 0.6-0.8wt.%, Mn 0.03-0.08wt.%, Cr≤0.02wt.%, Ti≤0.05wt.%, Fe≤0.10wt.%, and the balance is Al and unavoidable impurities.

2. The 6 series aluminum alloy for stamping back plate according to claim 1, characterized in that: The mass ratio of Mg to Si in the raw material composition of the 6-series aluminum alloy for the stamping back plate is (2-3):

1.

3. A processing technology for a 6 series aluminum alloy for a stamped back plate according to claim 1 or 2, 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 540-580°C for 16-20h, and then air-cooled to room temperature; The homogenized material is extruded, the extrusion rod temperature is 520-550°C, the outlet temperature is 500-530°C, and the extrusion speed is 0.3-1 m / min; The extruded material is punched and then subjected to a return treatment, and kept at 300-350°C for 2-30 seconds; The extruded material was artificially aged at 185°C for 9 hours.

4. The processing technology of 6 series aluminum alloy for stamping back plate according to claim 3 is characterized in that: In the extruded state, the number of strengthening phase Mg2Si with a size less than 1 micron is ≥6*10 6 Pieces / mm 2 .

5. The processing technology of 6 series aluminum alloy for stamping back plate according to claim 3 is characterized in that: In the aged state, the yield strength of the aluminum alloy is greater than 310MPa and the tensile strength is greater than 350MPa.

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