A high-strength 7-series aluminum alloy profile and its manufacturing method and application

Abstract

The present invention relates to the technical field of aluminum alloy production and processing, and discloses a high-strength 7-series aluminum alloy profile, its manufacturing method and application. The present invention optimizes the composition of the 7-series aluminum alloy, including adjusting the ratio of copper, magnesium and zinc, and adding a small amount of iron, manganese, lanthanum and other elements, which can not only improve the corrosion resistance of the material, but also reduce the generation of Fe phase, and the Fe phase will transform from β phase to α phase, thereby improving the mechanical properties of the material; in the preparation process, the present invention avoids adding Zr, thereby avoiding the problem of excessive grain refinement, resulting in a decrease in anodized gloss, and also avoids pollution to the environment, while reducing the cost of raw materials. The present invention adopts a two-stage homogenization process and a two-stage aging process, which can not only promote the complete solid solution of elements and the sufficient transformation of Fe phase, thereby improving the mechanical properties of the material, but also improve the corrosion resistance, and ensure that the microstructure of the aluminum alloy is uniform, thereby improving its use effect.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy production and processing, and in particular to a high-strength 7-series aluminum alloy profile and a manufacturing method and application thereof. Background Art

[0002] Aluminum alloys are widely used in aerospace, automotive, construction, electronics, and other fields. 7-series aluminum alloys, in particular, are widely used in industrial production and manufacturing due to their excellent mechanical properties and processing characteristics. However, aluminum alloys are susceptible to environmental factors during use, leading to corrosion, which in turn affects their service life and performance. Therefore, improving the corrosion resistance of 7-series aluminum alloys while maintaining their excellent mechanical properties is a key research topic in the fields of aluminum alloy preparation, metal corrosion protection, and metal material strength enhancement.

[0003] Existing technologies primarily improve the corrosion resistance and mechanical properties of aluminum alloys by modifying their composition and optimizing heat treatment processes. For example, the addition of elements such as copper, magnesium, and zinc can improve the strength and corrosion resistance of aluminum alloys. Furthermore, optimizing heat treatment processes, such as solution treatment and aging treatments, can further enhance the mechanical and corrosion resistance of aluminum alloys.

[0004] Although the existing technology has improved the corrosion resistance and mechanical properties of 7 series aluminum alloys to a certain extent, there are still some problems and shortcomings. First, the existing technology often requires the addition of a large amount of rare earth elements, such as zirconium, which not only increases production costs, but also may cause environmental pollution. Secondly, while the existing technology improves the corrosion resistance of aluminum alloys, it may sacrifice its mechanical properties, such as strength and hardness. Finally, when optimizing the heat treatment process, the existing technology often ignores the control of the microstructure of aluminum alloys, which will affect its use effect when applied to anodizing, making it difficult to use as the appearance of consumer products. Summary of the Invention

[0005] The purpose of the present invention is to provide a 7 series aluminum alloy profile that has both corrosion resistance and mechanical properties and good anodizing effect and a manufacturing method thereof, so as to provide at least one or more beneficial options for solving one or more technical problems existing in the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions.

[0007] A method for manufacturing a high-strength 7-series aluminum alloy profile comprises the following steps: 1) preparing alloy raw materials; the copper content is controlled to be 0.4-0.6 wt%; the magnesium content is controlled to be 2.0-2.5 wt%; the zinc content is controlled to be 6.5-7.5 wt%; the zinc / magnesium ratio is between 3-3.5; the iron content is less than 0.1 wt%; the manganese content is controlled to be 0.05-0.20 wt%; the lanthanum content is controlled to be 0.05-0.15 wt%; and the total content of other impurity elements is less than 0.05 wt% and the balance is aluminum; these raw materials are placed in a melting furnace and heated to melt into aluminum liquid; 2) Refining: Refining agent is added to the aluminum liquid for refining, standing and removing impurities; 3) Casting: The refined alloy liquid is poured into a preheated mold and cast into an aluminum alloy ingot; 4) Two-stage homogenization treatment: The aluminum alloy ingot is placed in a homogenization furnace and subjected to two-stage homogenization treatment; the first stage of homogenization process is at a holding temperature of 350-450℃ for 16-24h, and the second stage is at a holding temperature of 5 00-550℃, holding time is 4-8h; 5) Extrusion: the aluminum alloy ingot that has undergone double-stage homogenization treatment is placed in an extruder for extrusion; the extrusion ratio is 25-50; 6) Double-stage aging treatment: the extruded aluminum alloy profile is placed in an aging furnace for double-stage aging treatment; the holding temperature of the first stage aging process is 90-100℃, the holding time is 8-12h, and the second stage holding temperature is 130-140℃, the holding time is 12-20h.

[0008] More preferably, the method for manufacturing a high-strength 7 series aluminum alloy profile further comprises step 7) a surface treatment step: anodizing the aluminum alloy profile that has undergone the double-stage aging treatment to obtain a surface-treated aluminum alloy profile.

[0009] More preferably, in step 1) preparing the alloy raw materials, aluminum ingots, aluminum-copper master alloys, magnesium blocks, zinc blocks, aluminum-lanthanum master alloys and aluminum-lanthanum master alloys with a purity of 99.8% are selected as raw materials.

[0010] More preferably, in step 2) the refining step, the refining time is 30±10 minutes and the refining temperature is 700-750° C. After the refining is completed, the alloy liquid is allowed to stand for 30±10 minutes to allow impurities in the alloy liquid to settle.

[0011] More preferably, in step 3) the casting step, the refined alloy liquid is poured into a mold preheated to 200° C. for casting at a casting speed of 50±10 mm / min and a cooling speed of 10±5° C. / min.

[0012] More preferably, in step 5) the extrusion step, the temperature of the aluminum rod during extrusion is 450-500° C., and the quenching cooling method is water spraying or water cooling.

[0013] On the other hand, the present invention provides a high-strength 7 series aluminum alloy profile, which is manufactured using the above-mentioned method for manufacturing a high-strength 7 series aluminum alloy profile.

[0014] On the other hand, the present invention also provides a high-strength 7-series aluminum alloy profile specifically for a mobile phone middle frame, which is manufactured using the above-mentioned method for manufacturing a high-strength 7-series aluminum alloy profile.

[0015] On the other hand, the present invention also provides the use of the high-strength 7-series aluminum alloy profile described above in aviation products, automobile products, construction products or electronic products.

[0016] The present invention adopts the above technical solution to have at least the following beneficial effects.

[0017] 1. The present invention optimizes the composition of the 7-series aluminum alloy, including adjusting the ratios of copper, magnesium, and zinc, and adding small amounts of elements such as iron, manganese, and lanthanum. This not only improves the corrosion resistance of the material, but also reduces the production of the Fe phase, and the Fe phase transforms from the β phase to the α phase, thereby improving the material's mechanical properties, such as strength and hardness. The present invention improves the corrosion resistance and mechanical properties of the 7-series aluminum alloy without adding large amounts of rare earth elements (such as zirconium). While improving the corrosion resistance of the aluminum alloy, its mechanical properties, such as strength and hardness, are not affected.

[0018] Second, the present invention avoids adding Zr during the preparation process, thereby avoiding excessive grain refinement, which causes a decrease in the glossiness of anodized products, while also avoiding environmental pollution and reducing the cost of raw materials.

[0019] 3. The present invention adopts a two-stage homogenization process and a two-stage aging process, which can not only promote the complete solid solution of elements and the sufficient transformation of the Fe phase, thereby improving the mechanical properties of the material, but also enhance the corrosion resistance, and ensure the uniform microstructure of the aluminum alloy, thereby improving its use effect.

[0020] Fourth, the mobile phone middle frame of the present invention has good anodizing effect, can be made into high gloss, has good corrosion resistance, and has uniform grain structure, thus meeting the market demand for high quality of mobile phone middle frames. DETAILED DESCRIPTION

[0021] To facilitate those skilled in the art to better understand the essence of the present invention, the specific embodiments of the present invention are described in detail below.

[0022] A high-strength 7-series aluminum alloy profile, which can be specially used for a mobile phone middle frame, is prepared by the following steps.

[0023] 1) Optimize alloy composition: By adjusting the ratios of copper, magnesium, zinc, iron, manganese, and lanthanum in 7-series aluminum alloys, the corrosion resistance of the material is improved while reducing the formation of Fe phase, which will transform from β to α phase. The copper content is controlled at 0.4-0.6wt%; the magnesium content is controlled at 2.0-2.5wt%; the zinc content is controlled at 6.5-7.5wt%; and the zinc / magnesium ratio is controlled between 3-3.5. The iron content must be less than 0.1wt%, the manganese content is controlled at 0.05-0.20wt%, and the lanthanum content is controlled at 0.05-0.15wt%. The total content of other impurity elements is controlled at less than 0.05wt%.

[0024] 2) Optimize the heat treatment process: A two-stage homogenization process and a two-stage aging process are used to promote complete element solution, improve the material's mechanical properties, and enhance its corrosion resistance. The first-stage homogenization process uses a holding temperature of 350-450°C for 16-24 hours, while the second-stage uses a holding temperature of 500-550°C for 4-8 hours. The first-stage aging process uses a holding temperature of 90-100°C for 8-12 hours, while the second-stage uses a holding temperature of 130-140°C for 12-20 hours.

[0025] 3) Control the extrusion ratio and aluminum rod temperature: The extrusion ratio is controlled between 25-50 to promote recrystallization, control grain size and ensure uniformity; the aluminum rod temperature during extrusion is 450-500℃, and the quenching cooling method is water spraying or water cooling to ensure that the elements are completely dissolved without precipitation.

[0026] Through the above measures, the microstructure of aluminum alloys can be effectively controlled, and the grain size and uniformity can be controlled, ensuring uniform performance and improving its performance. The above technical means together constitute the core content of this technical solution. Through these technical means, the corrosion resistance of 7 series aluminum alloys can be improved without adding large amounts of rare earth elements (such as zirconium), while also not affecting its mechanical properties such as strength and hardness. Example 1

[0027] A method for manufacturing an ultra-high-strength 7-series aluminum alloy profile comprises the following steps.

[0028] 1) Prepare the alloy raw materials. Select 99.8% pure aluminum ingots, aluminum-copper master alloys, magnesium blocks, zinc blocks, aluminum-lanthanum master alloys, and aluminum-lanthanum master alloys as raw materials. By weight, the copper content is 0.43%, the magnesium content is 2.05%, the zinc content is 6.54%, the zinc / magnesium ratio is 3.19, the iron content is 0.08%, the manganese content is 0.06%, the lanthanum content is 0.06%, and the balance is aluminum. Place these raw materials in a melting furnace and heat to 750°C until they are completely melted.

[0029] 2) Refining. After the alloy material is completely melted, add a refining agent and continue refining for 30 minutes at a temperature of 750°C. After refining, let the alloy stand for 30 minutes to allow impurities in the alloy liquid to settle.

[0030] 3) Casting. The refined alloy liquid is poured into a mold preheated to 200°C and cast at a casting speed of 50 mm / min and a cooling rate of 10°C / min. After casting, an aluminum alloy ingot is obtained.

[0031] 4) Two-stage homogenization. The aluminum alloy ingot is placed in a homogenization furnace and subjected to a two-stage homogenization treatment. The first stage of homogenization is held at 400°C for 20 hours; the second stage is held at 550°C for 6 hours.

[0032] 5) Extrusion. The aluminum alloy ingot, which has undergone double-stage homogenization, is placed in an extruder for extrusion. The extrusion ratio is 30, the aluminum bar temperature during extrusion is 480°C, and the quenching cooling method is water spray cooling.

[0033] 6) Two-stage aging treatment. The extruded aluminum alloy profiles are placed in an aging furnace for a two-stage aging treatment. The first stage is at a holding temperature of 95°C for 10 hours; the second stage is at a holding temperature of 135°C for 16 hours.

[0034] 7) Surface Treatment. The aluminum alloy profile that has undergone the double-stage aging treatment is then anodized to obtain a surface-treated aluminum alloy profile. The above are the specific operating steps of this embodiment. This method can produce a high-strength, highly corrosion-resistant 7-series aluminum alloy. Example 2

[0035] A method for manufacturing an ultra-high-strength 7-series aluminum alloy profile comprises the following steps.

[0036] 1) Prepare the alloy raw materials. Select 99.8% pure aluminum ingots, aluminum-copper master alloy, magnesium block, zinc block, aluminum-lanthanum master alloy, and aluminum-lanthanum master alloy as the raw materials. By weight, the copper content is 0.57%, the magnesium content is 2.45%, the zinc content is 7.47%, the zinc / magnesium ratio is 3.05, the iron content is 0.09%, the manganese content is 0.13%, the lanthanum content is 0.13%, and the balance is aluminum. Place these raw materials in a melting furnace and heat to 750°C until they are completely melted.

[0037] 2) Refining. After the alloy material is completely melted, add a refining agent and continue refining for 30 minutes at a temperature of 750°C. After refining, let the alloy stand for 30 minutes to allow impurities in the alloy liquid to settle.

[0038] 3) Casting. The refined alloy liquid is poured into a mold preheated to 200°C and cast at a casting speed of 50 mm / min and a cooling rate of 10°C / min. After casting, an aluminum alloy ingot is obtained.

[0039] 4) Two-stage homogenization. The aluminum alloy ingot is placed in a homogenization furnace for a two-stage homogenization process. The first stage is held at 250°C for 24 hours; the second stage is held at 500°C for 4 hours.

[0040] 5) Extrusion. The aluminum alloy ingot, which has undergone double-stage homogenization, is placed in an extruder for extrusion. The extrusion ratio is 40, the aluminum bar temperature during extrusion is 500°C, and the quenching cooling method is water spray cooling.

[0041] 6) Two-stage aging treatment. The extruded aluminum alloy profiles are placed in an aging furnace for a two-stage aging treatment. The first stage of aging treatment is held at 100°C for 8 hours; the second stage of aging treatment is held at 140°C for 12 hours.

[0042] 7) Surface Treatment. The aluminum alloy profile that has undergone the double-stage aging treatment is then anodized to obtain a surface-treated aluminum alloy profile. The above are the specific operating steps of this embodiment. This method can produce a high-strength, highly corrosion-resistant 7-series aluminum alloy.

[0043] Comparative Example 1.

[0044] This comparative example is basically the same as Example 1, except that, in the prepared alloy raw material, calculated by weight percentage, the copper content is 0.44%, the magnesium content is 2.07%, the zinc content is 6.62%, the iron content is 0.08%, the manganese content is 0.07%, the lanthanum content is 0.07%, the zirconium content is 0.18%, and the balance is aluminum.

[0045] Comparative Example 2.

[0046] This comparative example is basically the same as Example 1, except that, in the prepared alloy raw materials, calculated by weight percentage, the copper content is 0.02%, the magnesium content is 2.15%, the zinc content is 6.71%, the iron content is 0.08%, the manganese content is 0.08%, the lanthanum content is 0.06%, and the balance is aluminum.

[0047] Comparative Example 3.

[0048] This comparative example is basically the same as Example 1, except that, in the prepared alloy raw material, calculated by weight percentage, the copper content is 0.65%, the magnesium content is 3.05%, the zinc content is 7.95%, the iron content is 0.10%, the manganese content is 0.16%, the lanthanum content is 0.16%, and the balance is aluminum.

[0049] Comparative Example 4.

[0050] This comparative example is basically the same as Example 1, except that the extrusion ratio is 15.

[0051] Performance testing.

[0052] In order to better reflect the technological progress of the present invention, the performance tests were carried out on the products prepared in Examples 1-2 and Comparative Examples 1-4, and the results are shown in Table 1.

[0053] Table 1. Performance test comparison table

[0054] .

[0055] As can be seen from Table 1, when the element zirconium is added to the alloy raw materials, the average grain size will be significantly reduced, the tensile strength and yield strength will also decrease, and the glossiness after anodizing will be insufficient.

[0056] When the copper element in the alloy raw material is lower than the lower limit, the tensile strength, yield strength and corrosion resistance of the product will decrease significantly.

[0057] When the extrusion ratio exceeds the lower limit of the limit range, the tensile strength, yield strength and corrosion resistance of the product will also decrease significantly.

[0058] It can be seen that the technical effect of the present invention is the result of the combined effect of alloy formula optimization and process optimization.

[0059] Due to the technological advancement of the present invention, the products produced by the present invention can be widely used in application fields such as aviation, automobiles, construction and electronics. In particular, in the field of mobile phone manufacturing, with the continuous development of the mobile phone market, the performance requirements for the mobile phone middle frame are getting higher and higher, including corrosion resistance, mechanical strength and appearance quality. The 7 series alloy of the present invention can not only improve the corrosion resistance of the mobile phone middle frame by optimizing the composition and heat treatment process, but also ensure its good mechanical properties and appearance quality, thus meeting the needs of mobile phone manufacturers. At the same time, the 7 series alloy of the present invention avoids the addition of a large amount of rare earth elements, reduces production costs, reduces pollution to the environment, and has a high environmental value. Therefore, the present invention has broad market prospects and application needs.

[0060] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The above embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make numerous modifications and improvements without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention. Any portions not described in the specific embodiments represent prior art or common knowledge.

[0062] It should also be noted that, in the description of the present invention, the detailed description of the preferred embodiment of the present invention and the included embodiments can more easily understand the content of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs. In the event of a conflict, the definitions in this specification shall prevail.

[0063] As used herein, the term "prepared from" is used synonymously with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0064] In the present invention, when amount, concentration or other value or parameter is expressed as a range, preferred range or a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including a range of "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc. When a numerical range is described in the present invention, unless otherwise stated, the range is intended to include its end value and all integers and fractions within the range.

[0065] In addition, the indefinite articles "a" and "an" before the elements or components of the present invention do not limit the quantity requirement (i.e., the number of times the elements or components appear). Therefore, "a" or "an" should be interpreted as including one or at least one, and elements or components in the singular also include plural forms, unless the number is obviously intended to be singular.

Claims

1. A method for manufacturing a high-strength 7 series aluminum alloy profile, characterized in that: The following steps are involved: 1) Prepare alloy raw materials; the copper content is controlled at 0.4-0.6wt%; the magnesium content is controlled at 2.0-2.5wt%; the zinc content is controlled at 6.5-7.5wt%; the zinc / magnesium ratio is between 3-3.5; the iron content is less than 0.1wt%; the manganese content is controlled at 0.05-0.20wt%; the lanthanum content is controlled at 0.05-0.15wt%; the total content of other impurity elements is less than 0.05wt%, and the balance is aluminum; place these raw materials in a melting furnace and heat and melt them into aluminum liquid; 2) Refining: adding refining agent to the aluminum liquid for refining, standing and removing impurities; 3) Casting: pouring the refined alloy liquid into a preheated mold to cast it into an aluminum alloy ingot; 4) Double-stage homogenization treatment: Place the aluminum alloy ingot into the homogenization furnace for double-stage homogenization treatment; the first stage of homogenization process has a holding temperature of 350-450°C and a holding time of 16-24 hours, and the second stage has a holding temperature of 500-550°C and a holding time of 4-8 hours; 5) Extrusion: Place the aluminum alloy ingot that has undergone double-stage homogenization treatment into an extruder for extrusion; the extrusion ratio is 25-50; 6) Double-stage aging treatment: Place the extruded aluminum alloy profile into an aging furnace for double-stage aging treatment; the first-stage aging process has a holding temperature of 90-100°C and a holding time of 8-12 hours, and the second-stage aging process has a holding temperature of 130-140°C and a holding time of 12-20 hours.

2. The method for manufacturing a high-strength 7 series aluminum alloy profile according to claim 1, characterized in that: The method further includes step 7) a surface treatment step of performing anodizing treatment on the aluminum alloy profile that has undergone the double-stage aging treatment to obtain a surface-treated aluminum alloy profile.

3. The method for manufacturing a high-strength 7 series aluminum alloy profile according to claim 1, characterized in that: In step 2) refining, the refining time is 30±10 minutes, and the refining temperature is 700-750°C. After refining, the alloy liquid is allowed to stand for 30±10 minutes to allow impurities in the alloy liquid to settle.

4. The method for manufacturing a high-strength 7 series aluminum alloy profile according to claim 1, characterized in that: In step 3) the casting step, the refined alloy liquid is poured into a mold preheated to 200° C. and cast at a casting speed of 50±10 mm / min and a cooling rate of 10±5° C. / min.

5. The method for manufacturing a high-strength 7 series aluminum alloy profile according to claim 1, characterized in that: In step 5) the extrusion step, the temperature of the aluminum rod during extrusion is 450-500° C., and the quenching cooling method is water spraying or water cooling.

6. A high-strength 7 series aluminum alloy profile, characterized in that: The high-strength 7 series aluminum alloy profile is manufactured using the manufacturing method of any one of claims 1 to 5.

7. A high-strength 7-series aluminum alloy profile specifically for mobile phone mid-frames, characterized in that: The high-strength 7 series aluminum alloy profile is manufactured using the manufacturing method of claim 2.

8. Use of the high-strength 7 series aluminum alloy profile as claimed in claim 6 in aviation products, automobile products or construction products.