High-strength aluminum profile for electronic product appearance part and preparation method of high-strength aluminum profile

Abstract

The invention discloses a high-strength aluminum profile for an electronic product outer part and a preparation method of the high-strength aluminum profile. The aluminum profile comprises the following components: 1.0-1.1% of Mg, 0.9-1.0% of Si, 0.6-0.7% of Cu, 0.2-0.3% of Mn, 0.005-0.01% of Ti, less than or equal to 0.1% of Fe and the balance of Al and inevitable impurities. The preparation method sequentially comprises the following steps: burdening, melting aluminum alloy liquid, detecting and adjusting components, blowing and refining in a furnace, refining grains, degassing and filtering, carrying out oil-gas sliding casting, homogenizing at high temperature, heating at gradient temperature, carrying out isothermal extrusion, stretching and straightening, sawing, framing and carrying out aging treatment. Through deep refining purification and large-extrusion-ratio isothermal extrusion, the cleanliness of the aluminum profile is improved, a completely recrystallized fine grain structure is obtained, the aluminum profile has high strength, high plasticity and excellent oxidation coloring performance, the tensile strength is larger than 450 MPa, the yield strength is larger than 410 MPa, the percentage elongation after fracture is larger than 10%, the 60-degree specular glossiness value of an oxidation film is larger than 150, and the aluminum profile is suitable for large-scale production. And the development requirements of larger, thinner, lighter and more beautiful electronic products such as smart phones, tablet personal computers, notebook computers and the like are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum profile preparation, and in particular relates to a high-strength aluminum profile for electronic product appearance parts and a preparation method thereof. Background Art

[0002] Aluminum alloys offer advantages such as low density, excellent heat dissipation, oxidation coloring, and a unique metallic luster and texture. They are widely used in exterior components such as casings, back panels, midframes, and bezels for electronic products such as smartphones, tablets, laptops, smartwatches, and e-readers. Aluminum alloy exterior components play a crucial role in supporting and protecting electronic products. Early aluminum alloy exterior components were primarily fabricated from medium-strength aluminum profiles such as 6063 and 6061. While these alloys offer excellent extrusion and oxidation coloring properties, their strength limitations are becoming increasingly prominent. As electronic devices grow larger and thinner, higher-strength aluminum alloys are urgently needed to improve their compressive and drop resistance, preventing bending, flexing, and screen crushing from impact or drops. Aluminum alloy exterior components also serve an important decorative purpose. After oxidation coloring, aluminum alloy exterior components can achieve a variety of vibrant colors and excellent wear and corrosion resistance, lending electronic products unparalleled aesthetic appeal and decorative appeal, meeting the needs of diverse consumer groups. With the development of the economy and society, consumers have increasingly higher requirements for the appearance and decorative effects of electronic products.

[0003] Chinese patent application CN114262827A discloses an aluminum alloy material with craters for mobile phone back panels. Its chemical composition and percentages by mass are as follows: Si ≤ 0.08%, Fe ≤ 0.16%, Cu ≤ 0.05%, Mn 0.25-0.3%, Mg 5.7-5.95%, Cr ≤ 0.1%, Zn ≤ 0.2%, Ti 0.015-0.03%, Na ≤ 0.0001%, Be 0.001-0.005%, with the remainder being aluminum and unavoidable impurities. This aluminum alloy has an elongation of no less than 12%, but its strength is relatively low, with a tensile strength of 380-400 MPa.

[0004] Chinese patent application CN107385290A discloses a high-strength aluminum alloy with excellent oxidation properties. The alloy comprises the following components, by mass: Si 0.6-0.9%, Mg 0.8-1.1%, Fe ≤ 0.2%, Cu 0.5-1%, Mn 0.2-0.5%, Ti 0.015-0.03%, B 0.0006-0.0012%, and other impurities totaling <0.15%, with the balance being Al. This aluminum alloy exhibits good plasticity, with an elongation of 10.6-13.4%, but exhibits relatively low strength, with a tensile strength of 405-415 MPa.

[0005] Chinese patent application CN110373583A discloses a high-quality, oxidation-resistant, high-strength aluminum alloy comprising the following composition by weight: Si 0.50-0.6%, Mg 2.2-2.8%, Fe ≤ 0.20%, Cu 0.55-0.75%, Cr ≤ 0.01%, Mn ≤ 0.3%, Ti ≤ 0.03%, with the balance being Al. This aluminum alloy exhibits high strength, with a tensile strength exceeding 420 MPa, but exhibits poor ductility, with an elongation of less than 8%.

[0006] Chinese patent application publication number CN113215456A discloses an Al-Mg-Si-Cu alloy extrusion and its production method. The extrusion comprises, by weight, 0.75-1.1% Si, ≤0.15% Fe, 0.75-1% Cu, 0.05-0.15% Mn, 0.85-1.3% Mg, ≤0.1% Cr, ≤0.1% Ti, with the balance being Al. The extruded alloy has a tensile strength of 406-433 MPa, exhibiting high strength and excellent anodizing properties, but exhibits poor ductility, with an elongation of less than 9%.

[0007] Based on literature research and practical experience, aluminum alloys used in electronic product exterior parts currently exhibit one or more of the following issues. First, due to the conflicting constraints between aluminum alloys' strength, ductility, and oxidation resistance, achieving a balanced balance between strength, ductility, and oxidation resistance is difficult. Increasing the strength of aluminum alloys results in decreased ductility and poor oxidation resistance, resulting in gray, dark, and yellow oxide films. This leads to low gloss and poor transparency, seriously affecting the purity of the color. Second, high-strength aluminum alloy extrusions are prone to coarse and fibrous crystals, resulting in defects such as striations, mottling, and color variations in the oxide film, severely impacting the film's color uniformity and texture. Finally, high-strength aluminum alloys are difficult to refine and purify, resulting in high gas slag content, which makes the oxide film susceptible to defects such as pinholes and black spots, failing to meet consumers' high expectations for the aesthetic and decorative effects of electronic products. Therefore, existing aluminum profiles used in electronic product exterior parts and their preparation still require improvement and development. Summary of the Invention

[0008] In response to the problems and shortcomings mentioned in the background technology, the present invention provides a high-strength aluminum profile for electronic product appearance parts and a preparation method thereof. By scientifically designing the composition of the aluminum profile, optimizing the preparation process of the aluminum profile, and improving the cleanliness of the aluminum profile, the aluminum profile obtains a fine and uniform grain structure, greatly improving the strength, plasticity and oxidation performance of the aluminum profile, and meeting the development needs of larger, thinner, lighter and more beautiful electronic products.

[0009] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are as follows:

[0010] A first aspect of the present invention provides a high-strength aluminum profile for electronic product appearance parts, characterized in that the aluminum profile is composed of the following components in mass percentage: Mg 1.0-1.1%, Si 0.9-1.0%, Cu 0.6-0.7%, Mn 0.2-0.3%, Ti 0.005-0.01%, Fe ≤ 0.1%, and the balance is Al and unavoidable impurities, with each unavoidable impurity ≤ 0.03% and the total impurities ≤ 0.1%.

[0011] Mg, Si, and Cu are the primary strengthening elements for aluminum profiles. Mg and Si form a Mg2Si phase, enhancing the strength of the aluminum profile, while Cu forms a CuAl2 phase with Al, further strengthening the profile. Higher Mg, Si, and Cu content increases the strength of the aluminum profile, but this also reduces its plasticity and oxidation resistance. To ensure sufficient strength while maintaining good plasticity and oxidation resistance, the preferred Mg content is 1.0-1.1%, Si 0.9-1.0%, and Cu 0.6-0.7%.

[0012] The main function of Mn in aluminum profiles is to dissolve and refine the Fe-rich phase, reducing the damage caused by coarse Fe-rich phases to the strength, plasticity, and oxidation resistance of the aluminum profile. Fe is an inevitable impurity element in aluminum profiles, and usually exists in the form of coarse Fe-rich phases, such as FeAl3, FeSiAl3, and Fe2SiAl8. Fe-rich phases are hard and brittle phases. First, they will split the aluminum matrix, reducing the strength and plasticity of the aluminum profile. Second, they will cause defects such as black lines after oxidation, reducing the aesthetic effect of electronic products. Therefore, the content of impurity element Fe must first be strictly controlled to keep the impurity Fe content ≤0.1%. Secondly, 0.2-0.3% Mn is added to the aluminum profile. Mn dissolves the impurity iron and forms fine (Fe, Mn)Al6 phases, reducing the damage caused by the coarse Fe-rich phase.

[0013] Ti is added to aluminum profiles in the form of an aluminum-titanium-carbon rare earth master alloy. Its primary function is to refine the grain size of the aluminum alloy ingot, prevent severe compositional segregation, improve the uniformity of its microstructure, and enhance its extrudability. The Ti content must be no less than 0.005%, otherwise the grain refinement effect will be minimal. However, the Ti content must also be no higher than 0.01%, otherwise a large number of TiC particles will form in the aluminum profile. These particles will easily agglomerate, leading to defects such as pinholes after CNC machining and oxidation.

[0014] A second aspect of the present invention provides a method for preparing a high-strength aluminum profile for an electronic product exterior part, which is characterized by comprising the following steps in sequence:

[0015] Step 1: According to the composition of aluminum profiles, aluminum ingots, magnesium ingots, crystalline silicon, aluminum-copper alloy and aluminum-manganese alloy are selected for batching;

[0016] Step 2: Heat the ingredients in an aluminum melting furnace to melt into aluminum alloy liquid;

[0017] Step 3: Stir the aluminum alloy liquid in the aluminum melting furnace, and then take samples for online composition detection and adjustment;

[0018] Step 4: Use nitrogen and flux to spray, refine, degas and remove slag on the aluminum alloy liquid in the aluminum melting furnace;

[0019] Step 5: The aluminum alloy liquid in the aluminum melting furnace is introduced into the launder, and then aluminum-titanium-carbon rare earth alloy rods are added for online grain refinement treatment;

[0020] Step 6: The aluminum alloy liquid is sequentially passed through a degassing box, a ceramic filter plate and an electromagnetic filter arranged on the launder for online degassing and slag removal treatment;

[0021] Step 7: The aluminum alloy liquid flows into the oil-gas sliding semi-continuous casting machine, and semi-continuously casts it into aluminum alloy round bars;

[0022] Step 8: Perform high-temperature homogenization treatment on the aluminum alloy round bar, and then spray water mist to cool it to room temperature;

[0023] Step 9: Preheat the aluminum alloy round bar with a gas furnace, and then heat it with an electromagnetic induction furnace at a gradient temperature;

[0024] Step 10: Extrude the heated aluminum alloy round bar into aluminum profiles, and then cool it to room temperature through water inline;

[0025] Step 11: The aluminum profiles are stretched, straightened, sawed and framed in sequence;

[0026] Step 12: Perform aging heat treatment on the aluminum profile, and obtain the high-strength aluminum profile for the electronic product appearance part after cooling to room temperature.

[0027] Preferably, the aluminum content of the aluminum ingot in step 1 is ≥99.85%, the magnesium content of the magnesium ingot is ≥99.9%, the silicon content of the crystalline silicon is ≥99.9%, the impurity content of the aluminum-copper alloy is ≤0.1%, and the impurity content of the aluminum-manganese alloy is ≤0.1%. In order to prevent defects such as sand holes, black spots, and black lines from appearing on the exterior parts of electronic products after oxidation and coloring, the purity of the aluminum profiles must be relatively high. In order to meet the purity requirements, the purity of the raw materials, aluminum ingots, magnesium ingots, crystalline silicon, aluminum-copper alloys, and aluminum-manganese alloys, must first be strictly controlled. Otherwise, it is easy to cause impurity elements such as Fe, Zn, and Cr in the aluminum profiles to exceed the standard, causing irreparable losses.

[0028] Preferably, the heating and melting of the aluminum alloy liquid in step 2 is performed at a temperature of 750-760° C. A too low melting temperature will result in slow melting and low production efficiency. A too high melting temperature should also not be used, as this will exacerbate oxidation and burning of the aluminum alloy liquid, increasing production costs.

[0029] Preferably, the stirring in step 3 is performed by using an electromagnetic stirrer or a permanent magnetic stirrer installed at the bottom of the aluminum melting furnace to stir the aluminum alloy liquid in the furnace to avoid segregation of the aluminum alloy liquid in the furnace and affect the uniformity of the composition. The online detection is to use a handheld spectrometer and a desktop spectrometer to quickly detect the sample composition. The adjustment is to further compensate for the content of an element by adding the pure metal or alloy of the element when the content is not reached. When the content of an element exceeds the content, it is diluted by adding aluminum ingots until the content of all elements in the aluminum alloy liquid reaches the content required by the aluminum profile.

[0030] Preferably, the purity of the nitrogen in step 4 is ≥99.9%, the volume percentage of oxygen in the nitrogen is ≤0.03%, and the water content is ≤0.3 g / m 3 The effectiveness of degassing and deslagging during nitrogen and flux spray refining of aluminum alloy liquid in the furnace is closely related to the purity of the nitrogen. If the nitrogen purity is low, or the oxygen and moisture content in the nitrogen is too high, the aluminum alloy liquid will oxidize and produce aluminum oxide slag during the spray refining degassing and deslagging process, and the decomposition of moisture will cause the aluminum alloy liquid to absorb hydrogen, thereby reducing the degassing and deslagging effect of the spray refining process and failing to obtain a highly clean aluminum alloy liquid.

[0031] Preferably, the flux described in step 4 is composed of the following components in mass percentage: AlCl3 36.12%, LiF2 8.37%, CuCO3 21.69%, Ce(NO3)3 13.82%. Existing fluxes are mainly composed of chlorides and fluorides of alkali metals such as Na, K, and Ca, which easily cause the content of alkali metals such as Na, K, and Ca in aluminum profiles to be too high. In particular, excessive Na content can cause sodium brittleness, seriously reducing the strength and plasticity of the aluminum profiles. In addition, excessive alkali metal content can also cause problems such as graying, darkening, and yellowing of the oxide film, reducing the glossiness and permeability of the oxide film, and affecting the purity of the coloring. In order to solve the problems existing in existing fluxes, the inventors have developed a flux that does not contain alkali metals and has a higher degassing and deslagging effect through a large number of experimental explorations and studies. Among them, AlCl3 is a white powder with a very low melting point and boiling point. It sublimates into bubbles in high-temperature aluminum alloy liquid, can absorb and take away slag and hydrogen in the aluminum alloy liquid, and play a degassing and deslagging effect. LiF forms molten salt in high-temperature aluminum alloy liquid, which can dissolve and adsorb slag inclusions such as aluminum oxide, increase the surface tension of the aluminum alloy liquid, promote the separation of slag inclusions from the aluminum alloy liquid, and improve the deslagging effect of the flux. CuCO3 decomposes into CO2 bubbles at 200°C. As the CO2 bubbles float up, they absorb and remove slag inclusions and hydrogen from the aluminum alloy liquid, playing a role in degassing and deslagging. The decomposed Cu atoms replenish the Cu content of the aluminum alloy liquid and enhance the strength of the aluminum profile. Ce(NO3)3, as a heat-generating agent, decomposes in the aluminum alloy liquid and releases a large amount of heat. First, it accelerates the dissolution of the flux in the aluminum alloy liquid and enhances the contact reaction between the flux and the aluminum alloy liquid. Second, it can also increase the temperature of the local aluminum alloy liquid, increase the fluidity of the aluminum alloy liquid, accelerate the floating and overflow of inclusions and hydrogen, and improve the degassing and deslagging effect. Finally, the decomposed NO and NO2 bubbles can also absorb and carry away inclusions and hydrogen, playing a role in degassing and slag removal. The decomposed rare earth element Ce has a strong affinity with hydrogen and oxygen, and can form stable rare earth hydrides and oxides. Due to its high density and high melting point, it finally precipitates at the bottom of the furnace, playing a role in fixing hydrogen and oxygen.

[0032] Preferably, the amount of flux used in step 4 is 0.3-0.4% of the weight of the aluminum alloy liquid, and the time of the spray refining is 20-30 minutes. The degassing and slag removal effect of the spray refining of nitrogen and flux is also related to the amount of flux used and the spray refining time. The greater the amount of flux used and the longer the spray refining time, the better the degassing and slag removal effect of the spray refining is. After spray refining, the hydrogen content of the aluminum alloy liquid can be reduced to below 0.3mL / 100gAl, but the limit hydrogen content will not be lower than 0.2mL / 100gAl. The reason is that the flux inevitably contains water, which will cause the aluminum alloy liquid to absorb hydrogen while spray refining degassing and slag removal, so that the dehydrogenation of the aluminum alloy liquid is always in a dynamic equilibrium process.

[0033] Preferably, the aluminum-titanium-carbon rare earth alloy rod in step five is composed of the following components in percentage by mass: Ti 5.0%, C 0.1%, La 0.05%, Ce 0.05%, Fe 0.07%, with the remainder being Al and unavoidable impurities, with each unavoidable impurity being ≤0.03% and the total amount of impurities being ≤0.1%. The amount of the aluminum-titanium-carbon rare earth alloy rod added is 0.1-0.2% of the weight of the aluminum alloy liquid. The grain refiner of existing aluminum alloys is mainly aluminum-titanium-boron alloy rod, and the addition amount is usually 0.2-0.4%. Too little addition will not have a grain refining effect. Too much addition will cause a large amount of TiB2 particles to be present in the aluminum profile, resulting in defects such as sand holes, black spots and black lines after CNC processing and oxidation. To address this issue, the inventors conducted extensive experimental research and developed a grain refiner for aluminum-titanium-carbon rare earth alloy rods. Because TiC particles possess a stronger grain-refining capability than TiB2 particles, the additive dosage can be reduced. Furthermore, the smaller TiC particle size compared to TiB2 particles achieves grain refinement while also preventing defects such as pinholes, black spots, and black lines that can occur after CNC machining and oxidation of aluminum profiles. Furthermore, the addition of trace amounts of the rare earth elements La and Ce to the alloy rod not only enhances grain refinement but also further refines the coarse, metamorphosed Fe-rich phase, improving the strength, plasticity, and oxidation resistance of the aluminum profile.

[0034] Preferably, the purified gas introduced into the degassing box in step 6 is a mixed gas composed of nitrogen and Freon gas, the volume percentage of Freon gas in the mixed gas is 14-16%, the purity of nitrogen is ≥99.99%, the purity of Freon gas is ≥99.9%, the volume percentage of oxygen content in the mixed gas is ≤0.03%, and the water content is ≤0.3g / m 3 , the flow rate of the mixed gas is 0.8-0.9L / kg aluminum alloy liquid. In the existing degassing box, inert gas nitrogen or argon, or a mixed gas composed of inert gas and chlorine is usually introduced. Due to the low density of the gas, the bubble floating speed is fast, resulting in a short contact time between the bubble and the aluminum alloy liquid, and a poor dehydrogenation effect. In addition, chlorine is a toxic and irritating gas that can corrode equipment and tools, making it dangerous to use. In order to improve the dehydrogenation effect of the degassing box, the present invention creatively introduces a mixed gas composed of nitrogen and Freon gas. Due to the high density, non-toxicity and stable chemical properties of Freon, the contact time between the bubble and the aluminum alloy liquid can be significantly increased. By adopting high-purity nitrogen and Freon gas, the dehydrogenation effect of the degassing box can be significantly improved. After dehydrogenation in the degassing box, the hydrogen content of the aluminum alloy liquid can be reduced to below 0.1mL / 100gAl, meeting the requirements of electronic products for high-cleanliness aluminum profiles.

[0035] Preferably, the porosity of the ceramic filter plate in step six is ​​50-60 mesh. In order to achieve deep filtration of the aluminum alloy liquid, the present invention creatively combines ceramic plate filtration and electromagnetic filtration. The aluminum alloy liquid is first passed through the ceramic filter plate for primary filtration to filter out inclusions larger than 20 μm in the aluminum alloy liquid. The aluminum alloy liquid is then passed through the electromagnetic filter for deep filtration. The electromagnetic filtration utilizes the characteristics that the aluminum alloy liquid is conductive while the inclusions are non-conductive. When the aluminum alloy liquid flows through the ceramic tube separator, an alternating magnetic field is applied through the induction coil, so that the aluminum alloy liquid is subjected to an electromagnetic force directed toward the center, while the inclusions are subjected to an electromagnetic repulsive force in the opposite direction, so that the inclusions gradually migrate to the inner surface of the ceramic tube separator and are enriched, thereby achieving separation of the inclusions from the aluminum alloy liquid. The principles and usage methods of the electromagnetic filter can be found in relevant literature and will not be elaborated here. After deep filtration by the electromagnetic filter, the removal rate of inclusions larger than 1 micron in the aluminum alloy liquid reaches more than 98%, and the volume content is less than 0.02 mm 2 / kgAl, thereby greatly improving the cleanliness of aluminum alloy liquid and meeting the requirements of electronic products for high-cleanliness aluminum profiles.

[0036] Preferably, during the semi-continuous casting described in step 7, the aluminum alloy liquid temperature is 700-710°C, the compressed air pressure is 0.3-0.4 MPa, the lubricating oil pressure is 0.6-0.7 MPa, the casting speed is 80-120 mm / min, and the cooling water temperature is ≤40°C. The oil-gas semi-continuous casting utilizes lubricant and compressed air as support surfaces in the casting mold, forming an oil-gas film between the aluminum alloy liquid and the mold, thereby reducing adhesion and friction between the aluminum alloy liquid and the mold walls. Oil-gas semi-continuous casting can reduce surface segregation of aluminum alloy round bars and improve the surface quality of the aluminum alloy shank, thereby increasing the quality and yield of the aluminum alloy round bars. Implementing oil-gas semi-continuous casting requires strict control of process parameters. The aluminum alloy liquid pressure should be neither too high nor too low during casting. The larger the diameter of the aluminum alloy round bar, the slower the casting speed should be, otherwise it is likely to cause leakage. The cooling water temperature should not be too high, otherwise the aluminum alloy round bar will not be effectively cooled.

[0037] Preferably, the temperature for the high-temperature homogenization treatment of the aluminum alloy round rod in step eight is 590-600°C, and the time for the homogenization treatment is 10-12 hours. The purpose of homogenizing the aluminum alloy round rod is to eliminate casting stress and component segregation and improve the extrusion performance of the aluminum alloy round rod. If the temperature of the homogenization treatment is lower than 590°C or the time is less than 10 hours, the casting stress and component segregation cannot be fully eliminated. If the temperature of the homogenization treatment is higher than 600°C, the aluminum alloy round rod will be overburned, which will deteriorate the structure and performance of the aluminum alloy round rod. Therefore, it is necessary to strictly control the temperature and time of the homogenization treatment of the aluminum alloy round rod.

[0038] Preferably, the temperature at which the aluminum alloy round bar is preheated using a gas furnace in step nine is 420°C, and the temperature gradient heating of the aluminum alloy round bar using an electromagnetic induction furnace is performed by dividing the aluminum alloy round bar into 6 sections, heating each section at a 10°C difference, with the heating temperature of the first section being 490-500°C and the heating temperature of the last section being 440-450°C, so that a temperature gradient of 50°C is formed from the first section to the last section of the aluminum alloy round bar. In conventional extrusion processes, due to the intense plastic deformation of the aluminum alloy round bar and the intense friction between the aluminum alloy round bar and the extrusion barrel, a large amount of heat is generated, causing the temperature of the aluminum alloy round bar to gradually increase, ultimately leading to a gradual increase in the temperature of the aluminum alloy in the extrusion deformation zone and the temperature of the outlet aluminum profile. Excessive temperature will first cause grain growth in the aluminum profile, making it impossible to obtain a fine and uniform grain structure. Secondly, it will cause defects such as cracking on the surface of the aluminum profile, affecting the surface quality. Finally, the mechanical properties of the front and rear ends of the aluminum profile will differ due to the different quenching temperatures, affecting the consistency and stability of the mechanical properties of the aluminum profile. The existing technology usually directly uses electromagnetic induction temperature gradient heating to heat aluminum alloy round bars. Due to the skin effect problem of electromagnetic induction heating, the temperature of the core and surface of the aluminum alloy round bar is uneven, which prolongs the electromagnetic induction heating time. Although the temperature difference between the core and the surface can be reduced, the temperature gradient in the longitudinal direction cannot be obtained. In addition, the heating time is long, which also increases energy consumption. In order to solve the problems existing in the existing technology, the present invention creatively combines gas heating and electromagnetic induction heating. First, gas is used to preheat the aluminum alloy round bar to 420℃, and then electromagnetic induction is used to perform temperature gradient heating on the aluminum alloy round bar. This can not only greatly reduce the temperature difference between the core and the surface of the aluminum alloy round bar, but also more accurately achieve temperature gradient heating, so that a temperature gradient of 50℃ is formed from the head section to the tail section of the aluminum alloy round bar. Finally, the temperature of the aluminum alloy in the extrusion deformation zone and the temperature of the outlet aluminum profile are always stable at 530-540℃, achieving approximate isothermal extrusion, ensuring that the aluminum profile obtains a fine and uniform grain structure, and ensuring the consistency and stability of the mechanical properties of the front and rear end aluminum profiles.

[0039] Preferably, during the extrusion in step 10, the upper temperature of the mold is 450-460°C, the extrusion ratio is 30-40, and the extrusion rod advancement speed is 3-5 mm / s. In order to obtain a fine and uniform grain structure for the aluminum profile and prevent the grains from growing and coarsening, the extrusion process parameters of the aluminum alloy round bar must be scientifically designed and strictly controlled. If the extrusion ratio is too small, the mold temperature is too low, or the temperature of the deformation zone is too low due to the extrusion speed being too slow, the aluminum profile cannot be induced to undergo complete recrystallization to form a fine grain structure. If the extrusion ratio is too large, the mold temperature is too high, or the extrusion speed is too fast, the temperature of the deformation zone is too high, which will cause the grains to grow and coarsen, and the aluminum profile will ultimately fail to obtain a fine and uniform grain structure. After the aluminum profile comes out, it should be immediately water-cooled to obtain a sufficiently high cooling rate for the aluminum profile to prevent the grains from growing and to obtain a supersaturated solid solution for the aluminum profile, so as to facilitate subsequent aging to improve the strength of the aluminum profile.

[0040] Preferably, the aging temperature of the aluminum profile in step 12 is 160-170°C, and the aging time is 8-9 hours. Aging heat treatment is an effective means to further improve the strength of the aluminum profile. Aging causes the aluminum profile to precipitate Mg2Si phase and CuAl2 phase, which can significantly enhance the strength of the aluminum profile. If the aging temperature is lower than 160°C or the aging time is less than 8 hours, the aluminum profile is in an under-aged state. If the aging temperature is higher than 170°C or the aging time is greater than 9 hours, the aluminum profile is in an over-aged state, and the aluminum profile cannot obtain ideal mechanical properties.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention improves the cleanliness of the aluminum profile, enables the aluminum profile to obtain a fully recrystallized fine-grained structure, greatly improves the strength, plasticity and anodizing performance of the aluminum profile, and solves the problem of mutual restriction and trade-off between strength, plasticity and anodizing performance. The aluminum profile has a tensile strength of greater than 450 MPa, a yield strength of greater than 410 MPa, an elongation after fracture of greater than 10%, and a 60° mirror gloss value of the oxide film greater than 150. It has high strength, good plasticity and excellent anodizing performance, effectively meeting the development needs of larger, thinner, lighter and more beautiful electronic products such as smart phones, tablets and laptops. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a microstructure diagram of the cross section of the aluminum profile in Example 1 magnified 100 times.

[0044] Figure 2 This is a microstructure diagram of the cross section of the aluminum profile of Comparative Example 5 magnified 100 times. DETAILED DESCRIPTION

[0045] Example 1:

[0046] The high-strength aluminum profile for electronic product appearance parts is composed of the following components in percentage by mass: Mg 1.08%, Si 0.96%, Cu 0.65%, Mn 0.24%, Ti 0.0075%, Fe ≤ 0.1%, and the balance is Al and unavoidable impurities, with each unavoidable impurity ≤ 0.03% and the total impurities ≤ 0.1%. The preparation method comprises the following steps in sequence:

[0047] Step 1: According to the composition of the aluminum profile, aluminum ingots with an aluminum content of 99.85%, magnesium ingots with a magnesium content of 99.9%, crystalline silicon with a silicon content of 99.9%, aluminum-copper alloy with an impurity content of ≤0.1%, and aluminum-manganese alloy with an impurity content of ≤0.1% are selected for batching;

[0048] Step 2: Heat the ingredients in an aluminum melting furnace at 755°C to melt into aluminum alloy liquid;

[0049] Step 3: Use the electromagnetic stirrer installed at the bottom of the aluminum melting furnace to stir the aluminum alloy liquid, and then take samples for online composition detection and adjustment;

[0050] Step 4: Use 99.9% pure nitrogen and 0.35% flux by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid in the aluminum melting furnace for 25 minutes to degas and remove slag. The volume percentage of oxygen in the nitrogen is ≤0.03%, and the water content is ≤0.3g / m 3 , the flux is composed of the following components in mass percentage: AlCl3 36.12%, LiF 28.37%, CuCO3 21.69%, Ce(NO3)3 13.82%;

[0051] Step 5: introducing the aluminum alloy liquid in the aluminum melting furnace into a launder, and then adding an aluminum-titanium-carbon rare earth alloy rod having a weight percentage of 0.15% of the aluminum alloy liquid for online grain refinement, wherein the aluminum-titanium-carbon rare earth alloy rod is composed of the following components in mass percentage: Ti 5.0%, C 0.1%, La 0.05%, Ce 0.05%, Fe 0.07%, and the balance is Al and unavoidable impurities, wherein the unavoidable impurities are ≤0.03% each and the total impurities are ≤0.1%;

[0052] Step 6: The aluminum alloy liquid is passed through a degassing box, a 50-mesh ceramic filter plate, and an electromagnetic filter in sequence on the flow trough for online degassing and slag removal. A mixed gas composed of nitrogen and Freon gas is introduced into the degassing box. The volume percentage of Freon gas in the mixed gas is 15%, and the flow rate of the mixed gas is 0.85 L / kg aluminum alloy liquid. The purity of the nitrogen is 99.99%, the purity of the Freon gas is 99.9%, the volume percentage of oxygen content in the mixed gas is ≤0.03%, and the water content is ≤0.3 g / m 3 ;

[0053] Step 7: The aluminum alloy liquid is flowed into an oil-gas semi-continuous casting machine, and semi-continuously cast into aluminum alloy round bars under the conditions of aluminum alloy liquid temperature of 705°C, compressed air pressure of 0.35MPa, lubricating oil pressure of 0.65MPa, casting speed of 100mm / min and cooling water temperature of 40°C;

[0054] Step 8: homogenize the aluminum alloy round bar at 595°C for 11 hours, then spray water and cool it to room temperature;

[0055] Step 9: First, preheat the aluminum alloy round bar to 420℃ in a gas furnace, and then use an electromagnetic induction furnace to divide the aluminum alloy round bar into 6 sections, with a temperature difference of 10℃ in each section, and perform gradient heating. The heating temperature of the first section is 495℃, and the heating temperature of the last section is 445℃, so that a temperature gradient of 50℃ is formed from the first section to the last section.

[0056] Step 10: The heated aluminum alloy round bar is extruded into an aluminum profile under the conditions of a mold upper machine temperature of 455°C, an extrusion ratio of 35, and an extrusion rod advancing speed of 4 mm / s, and then cooled to room temperature through water in an online process;

[0057] Step 11: The aluminum profiles are stretched, straightened, sawed and framed in sequence;

[0058] Step 12: subjecting the aluminum profile to aging heat treatment at 165° C. for 8.5 hours and cooling to room temperature to obtain the high-strength aluminum profile for the electronic product appearance part.

[0059] Example 2:

[0060] The high-strength aluminum profile for electronic product appearance parts is composed of the following components in percentage by mass: Mg 1.03%, Si 0.98%, Cu 0.69%, Mn 0.21%, Ti 0.005%, Fe ≤ 0.1%, and the balance is Al and unavoidable impurities, with each unavoidable impurity ≤ 0.03% and the total impurities ≤ 0.1%. The preparation method comprises the following steps in sequence:

[0061] Step 1: According to the composition of the aluminum profile, aluminum ingots with an aluminum content of 99.9%, magnesium ingots with a magnesium content of 99.95%, crystalline silicon with a silicon content of 99.95%, aluminum-copper alloy with an impurity content of ≤0.1%, and aluminum-manganese alloy with an impurity content of ≤0.1% are selected for batching;

[0062] Step 2: Heat the ingredients in an aluminum melting furnace at 750°C to melt into aluminum alloy liquid;

[0063] Step 3: Use the electromagnetic stirrer installed at the bottom of the aluminum melting furnace to stir the aluminum alloy liquid, and then take samples for online composition detection and adjustment;

[0064] Step 4: Use 99.9% pure nitrogen and 0.3% flux by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid in the aluminum melting furnace for 30 minutes to degas and remove slag. The volume percentage of oxygen in the nitrogen is ≤0.03%, and the water content is ≤0.3g / m 3 , the flux is composed of the following components in mass percentage: AlCl3 36.12%, LiF 28.37%, CuCO3 21.69%, Ce(NO3)3 13.82%;

[0065] Step 5: introducing the aluminum alloy liquid in the aluminum melting furnace into the launder, and then adding an aluminum-titanium-carbon rare earth alloy rod with a weight percentage of 0.1% of the aluminum alloy liquid for online grain refinement, wherein the aluminum-titanium-carbon rare earth alloy rod is composed of the following components in mass percentage: Ti 5.0%, C 0.1%, La 0.05%, Ce 0.05%, Fe 0.07%, and the balance is Al and unavoidable impurities, with each unavoidable impurity being ≤0.03% and the total impurities being ≤0.1%;

[0066] Step 6: The aluminum alloy liquid is sequentially passed through a degassing box, a 60-mesh ceramic filter plate, and an electromagnetic filter arranged on the flow trough for online degassing and slag removal. A mixed gas composed of nitrogen and Freon gas is introduced into the degassing box. The volume percentage of Freon gas in the mixed gas is 16%, and the flow rate of the mixed gas is 0.8 L / kg aluminum alloy liquid. The purity of the nitrogen is 99.99%, the purity of the Freon gas is 99.9%, the volume percentage of oxygen content in the mixed gas is ≤0.03%, and the water content is ≤0.3 g / m 3 ;

[0067] Step 7: The aluminum alloy liquid is flowed into an oil-gas semi-continuous casting machine, and semi-continuously cast into aluminum alloy round bars under the conditions of aluminum alloy liquid temperature of 700°C, compressed air pressure of 0.4MPa, lubricating oil pressure of 0.6MPa, casting speed of 120mm / min and cooling water temperature of 30°C;

[0068] Step 8: homogenize the aluminum alloy round bar at 600°C for 10 hours, then spray water and cool it to room temperature;

[0069] Step 9: First, preheat the aluminum alloy round bar to 420℃ in a gas furnace, and then use an electromagnetic induction furnace to divide the aluminum alloy round bar into 6 sections, with a temperature difference of 10℃ in each section, and perform gradient heating. The heating temperature of the first section is 500℃, and the heating temperature of the last section is 450℃, so that a temperature gradient of 50℃ is formed from the first section to the last section.

[0070] Step 10: Extrude the heated aluminum alloy round bar into aluminum profiles under the conditions of a mold upper machine temperature of 460°C, an extrusion ratio of 40, and an extrusion rod advancing speed of 3 mm / s, and then cool it to room temperature through water online;

[0071] Step 11: The aluminum profiles are stretched, straightened, sawed and framed in sequence;

[0072] Step 12: subjecting the aluminum profile to aging heat treatment at 160° C. for 9 hours and cooling to room temperature to obtain the high-strength aluminum profile for the electronic product appearance part.

[0073] Example 3:

[0074] The high-strength aluminum profile for electronic product appearance parts is composed of the following components in percentage by mass: Mg 1.1%, Si 0.9%, Cu 0.6%, Mn 0.3%, Ti 0.01%, Fe ≤ 0.1%, and the balance is Al and unavoidable impurities, with each unavoidable impurity ≤ 0.03% and the total impurities ≤ 0.1%. The preparation method comprises the following steps in sequence:

[0075] Step 1: According to the composition of the aluminum profile, aluminum ingots with an aluminum content of 99.85%, magnesium ingots with a magnesium content of 99.9%, crystalline silicon with a silicon content of 99.9%, aluminum-copper alloy with an impurity content of ≤0.1%, and aluminum-manganese alloy with an impurity content of ≤0.1% are selected for batching;

[0076] Step 2: Heat the ingredients in an aluminum melting furnace at 760°C to melt into aluminum alloy liquid;

[0077] Step 3: Use the electromagnetic stirrer installed at the bottom of the aluminum melting furnace to stir the aluminum alloy liquid, and then take samples for online composition detection and adjustment;

[0078] Step 4: Use 99.9% pure nitrogen and 0.3% flux by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid in the aluminum melting furnace for 20 minutes to degas and remove slag. The volume percentage of oxygen in the nitrogen is ≤0.03%, and the water content is ≤0.3g / m 3 , the flux is composed of the following components in mass percentage: AlCl3 36.12%, LiF 28.37%, CuCO3 21.69%, Ce(NO3)3 13.82%;

[0079] Step 5: introducing the aluminum alloy liquid in the aluminum melting furnace into a launder, and then adding an aluminum-titanium-carbon rare earth alloy rod containing 0.2% by weight of the aluminum alloy liquid for online grain refinement, wherein the aluminum-titanium-carbon rare earth alloy rod is composed of the following components by mass percentage: Ti 5.0%, C 0.1%, La 0.05%, Ce 0.05%, Fe 0.07%, and the balance is Al and unavoidable impurities, with each unavoidable impurity being ≤0.03% and the total impurities being ≤0.1%;

[0080] Step 6: The aluminum alloy liquid is passed through a degassing box, a 50-mesh ceramic filter plate, and an electromagnetic filter in sequence on the flow trough for online degassing and slag removal. A mixed gas composed of nitrogen and Freon gas is introduced into the degassing box. The volume percentage of Freon gas in the mixed gas is 14%, and the flow rate of the mixed gas is 0.9 L / kg aluminum alloy liquid. The purity of the nitrogen is 99.99%, the purity of the Freon gas is 99.9%, the volume percentage of oxygen content in the mixed gas is ≤0.03%, and the water content is ≤0.3 g / m 3 ;

[0081] Step 7: The aluminum alloy liquid is flowed into an oil-gas semi-continuous casting machine, and semi-continuously cast into aluminum alloy round bars under the conditions of aluminum alloy liquid temperature of 710°C, compressed air pressure of 0.3MPa, lubricating oil pressure of 0.7MPa, casting speed of 80mm / min and cooling water temperature of 28°C;

[0082] Step 8: homogenize the aluminum alloy round bar at 590°C for 12 hours, then spray water and cool it to room temperature;

[0083] Step 9: First, preheat the aluminum alloy round bar to 420℃ in a gas furnace, and then use an electromagnetic induction furnace to divide the aluminum alloy round bar into 6 sections, with a temperature difference of 10℃ in each section, and perform gradient heating. The heating temperature of the first section is 490℃, and the heating temperature of the last section is 440℃, so that a temperature gradient of 50℃ is formed from the first section to the last section.

[0084] Step 10: Extrude the heated aluminum alloy round bar into aluminum profiles under the conditions of a mold upper machine temperature of 450°C, an extrusion ratio of 30, and an extrusion rod advancing speed of 5 mm / s, and then cool it to room temperature online through water;

[0085] Step 11: The aluminum profiles are stretched, straightened, sawed and framed in sequence;

[0086] Step 12: subjecting the aluminum profile to aging heat treatment at 170° C. for 8 hours and cooling to room temperature to obtain the high-strength aluminum profile for the electronic product appearance part.

[0087] Example 4:

[0088] The high-strength aluminum profile for electronic product appearance parts is composed of the following components in percentage by mass: Mg 1.0%, Si 1.0%, Cu 0.7%, Mn 0.2%, Ti 0.005%, Fe ≤ 0.1%, and the balance is Al and unavoidable impurities, with each unavoidable impurity ≤ 0.03% and the total impurities ≤ 0.1%. The preparation method comprises the following steps in sequence:

[0089] Step 1: According to the composition of the aluminum profile, aluminum ingots with an aluminum content of 99.85%, magnesium ingots with a magnesium content of 99.9%, crystalline silicon with a silicon content of 99.9%, aluminum-copper alloy with an impurity content of ≤0.1%, and aluminum-manganese alloy with an impurity content of ≤0.1% are selected for batching;

[0090] Step 2: Heat the ingredients in an aluminum melting furnace at 750°C to melt into aluminum alloy liquid;

[0091] Step 3: Use the electromagnetic stirrer installed at the bottom of the aluminum melting furnace to stir the aluminum alloy liquid, and then take samples for online composition detection and adjustment;

[0092] Step 4: Use 99.9% pure nitrogen and 0.4% flux by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid in the aluminum melting furnace for 30 minutes to degas and remove slag. The volume percentage of oxygen in the nitrogen is ≤0.03%, and the water content is ≤0.3g / m 3 , the flux is composed of the following components in mass percentage: AlCl3 36.12%, LiF 28.37%, CuCO3 21.69%, Ce(NO3)3 13.82%;

[0093] Step 5: introducing the aluminum alloy liquid in the aluminum melting furnace into the launder, and then adding an aluminum-titanium-carbon rare earth alloy rod with a weight percentage of 0.1% of the aluminum alloy liquid for online grain refinement, wherein the aluminum-titanium-carbon rare earth alloy rod is composed of the following components in mass percentage: Ti 5.0%, C 0.1%, La 0.05%, Ce 0.05%, Fe 0.07%, and the balance is Al and unavoidable impurities, with each unavoidable impurity being ≤0.03% and the total impurities being ≤0.1%;

[0094] Step 6: The aluminum alloy liquid is sequentially passed through a degassing box, a 60-mesh ceramic filter plate, and an electromagnetic filter arranged on the flow trough for online degassing and slag removal. A mixed gas composed of nitrogen and Freon gas is introduced into the degassing box. The volume percentage of Freon gas in the mixed gas is 16%, and the flow rate of the mixed gas is 0.8 L / kg aluminum alloy liquid. The purity of the nitrogen is 99.99%, the purity of the Freon gas is 99.9%, the volume percentage of oxygen content in the mixed gas is ≤0.03%, and the water content is ≤0.3 g / m 3 ;

[0095] Step 7: The aluminum alloy liquid is flowed into an oil-gas semi-continuous casting machine, and semi-continuously cast into aluminum alloy round bars under the conditions of aluminum alloy liquid temperature of 700°C, compressed air pressure of 0.4MPa, lubricating oil pressure of 0.6MPa, casting speed of 90mm / min and cooling water temperature of 20°C;

[0096] Step 8: homogenize the aluminum alloy round bar at 595°C for 11 hours, then spray water and cool it to room temperature;

[0097] Step 9: First, preheat the aluminum alloy round bar to 420℃ in a gas furnace, and then use an electromagnetic induction furnace to divide the aluminum alloy round bar into 6 sections, with a temperature difference of 10℃ in each section, and perform gradient heating. The heating temperature of the first section is 495℃, and the heating temperature of the last section is 445℃, so that a temperature gradient of 50℃ is formed from the first section to the last section.

[0098] Step 10: Extrude the heated aluminum alloy round bar into aluminum profiles under the conditions of a mold upper machine temperature of 455°C, an extrusion ratio of 38, and an extrusion rod advancing speed of 4.5 mm / s, and then cool it to room temperature online through water;

[0099] Step 11: The aluminum profiles are stretched, straightened, sawed and framed in sequence;

[0100] Step 12: subjecting the aluminum profile to aging heat treatment at 165° C. for 8.5 hours and cooling to room temperature to obtain the high-strength aluminum profile for the electronic product appearance part.

[0101] Example 5:

[0102] The high-strength aluminum profile for electronic product appearance parts is composed of the following components in percentage by mass: Mg 1.05%, Si 0.96%, Cu 0.63%, Mn 0.28%, Ti 0.075%, Fe ≤ 0.1%, and the balance is Al and unavoidable impurities, with each unavoidable impurity ≤ 0.03% and the total impurities ≤ 0.1%. The preparation method comprises the following steps in sequence:

[0103] Step 1: According to the composition of the aluminum profile, aluminum ingots with an aluminum content of 99.85%, magnesium ingots with a magnesium content of 99.9%, crystalline silicon with a silicon content of 99.9%, aluminum-copper alloy with an impurity content of ≤0.1%, and aluminum-manganese alloy with an impurity content of ≤0.1% are selected for batching;

[0104] Step 2: Heat the ingredients in an aluminum melting furnace at 755°C to melt into aluminum alloy liquid;

[0105] Step 3: Use the electromagnetic stirrer installed at the bottom of the aluminum melting furnace to stir the aluminum alloy liquid, and then take samples for online composition detection and adjustment;

[0106] Step 4: Use 99.9% pure nitrogen and 0.35% flux by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid in the aluminum melting furnace for 25 minutes to degas and remove slag. The volume percentage of oxygen in the nitrogen is ≤0.03%, and the water content is ≤0.3g / m 3 , the flux is composed of the following components in mass percentage: AlCl3 36.12%, LiF 28.37%, CuCO3 21.69%, Ce(NO3)3 13.82%;

[0107] Step 5: introducing the aluminum alloy liquid in the aluminum melting furnace into a launder, and then adding an aluminum-titanium-carbon rare earth alloy rod having a weight percentage of 0.15% of the aluminum alloy liquid for online grain refinement, wherein the aluminum-titanium-carbon rare earth alloy rod is composed of the following components in mass percentage: Ti 5.0%, C 0.1%, La 0.05%, Ce 0.05%, Fe 0.07%, and the balance is Al and unavoidable impurities, wherein the unavoidable impurities are ≤0.03% each and the total impurities are ≤0.1%;

[0108] Step 6: The aluminum alloy liquid is passed through a degassing box, a 50-mesh ceramic filter plate, and an electromagnetic filter in sequence on the flow trough for online degassing and slag removal. A mixed gas composed of nitrogen and Freon gas is introduced into the degassing box. The volume percentage of Freon gas in the mixed gas is 15%, and the flow rate of the mixed gas is 0.85 L / kg aluminum alloy liquid. The purity of the nitrogen is 99.99%, the purity of the Freon gas is 99.9%, the volume percentage of oxygen content in the mixed gas is ≤0.03%, and the water content is ≤0.3 g / m 3 ;

[0109] Step 7: The aluminum alloy liquid is flowed into an oil-gas semi-continuous casting machine, and semi-continuously cast into aluminum alloy round bars under the conditions of aluminum alloy liquid temperature of 705°C, compressed air pressure of 0.35MPa, lubricating oil pressure of 0.65MPa, casting speed of 110mm / min and cooling water temperature of 35°C;

[0110] Step 8: homogenize the aluminum alloy round bar at 590°C for 12 hours, then spray water and cool it to room temperature;

[0111] Step 9: First, preheat the aluminum alloy round bar to 420℃ in a gas furnace, and then use an electromagnetic induction furnace to divide the aluminum alloy round bar into 6 sections, with a temperature difference of 10℃ in each section, and perform gradient heating. The heating temperature of the first section is 500℃, and the heating temperature of the last section is 450℃, so that a temperature gradient of 50℃ is formed from the first section to the last section.

[0112] Step 10: Extrude the heated aluminum alloy round bar into aluminum profiles under the conditions of a mold upper machine temperature of 460°C, an extrusion ratio of 40, and an extrusion rod advancing speed of 3 mm / s, and then cool it to room temperature online through water;

[0113] Step 11: The aluminum profiles are stretched, straightened, sawed and framed in sequence;

[0114] Step 12: subjecting the aluminum profile to aging heat treatment at 170° C. for 8 hours and cooling to room temperature to obtain the high-strength aluminum profile for the electronic product appearance part.

[0115] Comparative Example 1:

[0116] The preparation method of the aluminum profile for electronic product appearance parts in this comparative example is the same as that in Example 1, except that the aluminum profile for electronic product appearance parts is composed of the following components in mass percentage: Mg 0.96%, Si 0.85%, Cu 0.65%, Mn 0.24%, Ti 0.0075%, Fe ≤ 0.1%, and the balance is Al and unavoidable impurities, with a single unavoidable impurity ≤ 0.03% and a total of impurities ≤ 0.1%.

[0117] Comparative Example 2:

[0118] The composition and preparation process of the aluminum profile for electronic product appearance parts in this comparative example are the same as those in Example 1, except that the flux used in step 4 is an existing conventional flux, which is composed of the following components in mass percentage: NaCl 46.71%, KCl 30.62%, and Na3AlF6 22.67%.

[0119] Comparative Example 3:

[0120] The composition and preparation process of the aluminum profile for the appearance of electronic products in this comparative example are the same as those in Example 1, except that in step five, 0.15% by weight of an aluminum-titanium-boron alloy rod is added to the aluminum alloy liquid for online grain refinement treatment. The aluminum-titanium-boron alloy rod is composed of the following components in mass percentage: Ti 5.0%, B 1.0%, and the balance being Al and unavoidable impurities, with each unavoidable impurity being ≤0.03% and the total impurities being ≤0.1%.

[0121] Comparative Example 4:

[0122] The composition and preparation process of the aluminum profile for the electronic product appearance parts in this comparative example are the same as those in Example 1, except that in step nine, the aluminum alloy round rod is not subjected to gradient temperature heating in an electromagnetic induction furnace. Instead, the aluminum alloy round rod is directly heated to 495°C in a gas furnace and then fed into an extruder for extrusion forming.

[0123] Comparative Example 5:

[0124] The composition and preparation process of the aluminum profile for the electronic product appearance part in this comparative example are the same as those in Example 1, except that the upper machine temperature of the mold in step 10 is 470°C, the extrusion ratio is 25, and the extrusion rod advancement speed is 6 mm / s.

[0125] Verification Example 1:

[0126] Samples were taken from the middle of the aluminum profiles for electronic product exterior parts obtained in Examples 1-5 and Comparative Examples 1-5. Tensile test specimens were processed according to the national standard GB / T 16865-2013, "Test specimens and methods for tensile testing of wrought aluminum, magnesium, and their alloys." The specimens were then stretched at room temperature on an electronic tensile testing machine. The tensile strength, yield strength, and elongation at break of the aluminum profiles were measured. The results are shown in Table 1. The samples were anodized and their specular gloss at a 60° angle was measured according to the national standard GB / T 20503-2006, "Determination of specular reflectivity and specular gloss of anodic oxide films of aluminum and aluminum alloys." The results are shown in Table 1. As shown in Table 1, the aluminum profiles in Examples 1-5 exhibited tensile strengths exceeding 450 MPa, yield strengths exceeding 410 MPa, elongations exceeding 10%, and a 60° specular gloss value of the oxide film exceeding 150. These aluminum profiles exhibited both high strength and ductility, as well as excellent anodization performance. Although the aluminum profile in Comparative Example 1 has high plasticity, the strength of the aluminum profile is low due to insufficient Mg and Si content. Comparative Example 2 uses existing conventional flux, resulting in low strength, plasticity and oxide film mirror gloss values ​​of the aluminum profile. Comparative Example 3 adds existing conventional aluminum-titanium-boron alloy rod grain refiner. Under the same addition amount, the grain refinement is insufficient, resulting in low strength and plasticity of the aluminum profile. Comparative Example 4 does not use an electromagnetic induction furnace for gradient heating, but uses a gas furnace for direct heating, which makes the temperature of the extrusion deformation zone and the outlet aluminum profile too high, deteriorating the performance of the aluminum profile. The strength, plasticity and oxide film mirror gloss values ​​of the aluminum profile are all low. Comparative Example 5 also has low strength, plasticity and oxide film mirror gloss values ​​of the aluminum profile due to unreasonable matching of the extrusion process parameters of the aluminum alloy round bar.

[0127] Table 1 Tensile mechanical properties of aluminum profiles

[0128]

[0129]

[0130] Verification Example 2:

[0131] Samples were taken from the head, middle, and tail positions of the aluminum profiles of Example 1 and Comparative Example 4, respectively. The tensile test specimens were processed according to the national standard GB / T 16865, "Test Specimens and Methods for Tensile Testing of Deformed Aluminum, Magnesium, and Their Alloy Products." The specimens were then stretched at room temperature on an electronic tensile testing machine. The tensile strength, yield strength, and elongation at break of the aluminum profiles at the head, middle, and tail positions were measured. The results are shown in Table 2. In Example 1, the aluminum alloy round bar was preheated in a gas furnace and then subjected to gradient heating in an electromagnetic induction furnace, resulting in a temperature gradient of 50°C from the head to the tail. Since the temperature of the tail section was lower than that of the head section, deformation heat and friction heat were effectively offset, allowing the temperature of the outlet aluminum profile to remain stable throughout the entire aluminum alloy round bar extrusion process. Ultimately, the mechanical properties of the aluminum profiles at the head, middle, and tail positions remained stable. As can be seen from Table 2, the fluctuation range of the tensile strength and yield strength of the aluminum profile at the head, middle, and tail positions of Example 1 was less than 10 MPa, and the fluctuation range of the elongation was less than 0.5%. Since Comparative Example 4 does not use an electromagnetic induction furnace for temperature gradient heating, but instead uses a gas furnace for direct heating, the temperature of the aluminum alloy round bar is the same at both the head and tail. As the extrusion deformation heat and friction heat accumulate, the temperature of the extrusion deformation zone and the outlet aluminum profile temperature will gradually increase. Excessively high outlet temperatures will first cause the aluminum profile grains to grow, reducing the mechanical properties of the aluminum profile. Secondly, they will deteriorate the surface quality of the aluminum profile, leading to surface defects such as tearing and cracking. As can be seen from Table 2, the strength and plasticity of the aluminum profile in Comparative Example 4 are significantly lower than those in the head section. The fluctuation range of the tensile strength and yield strength at the head, middle, and tail positions of the aluminum profile exceeds 20 MPa, and the fluctuation range of the elongation after fracture exceeds 1%. By comparison, it can be seen that the mechanical property consistency and stability of the aluminum profile in Example 1 are significantly better than those of the aluminum profile in Comparative Example 4.

[0132] Table 2 Tensile mechanical properties of aluminum profiles

[0133]

[0134] Verification Example 3:

[0135] Samples were taken from the middle of the aluminum profiles of Example 1 and Comparative Example 5, and after grinding, polishing and etching, the microstructures of the samples were observed under an optical microscope. Figure 1 The microstructure of the cross section of the aluminum profile in Example 1 is magnified 100 times. Figure 2 The microstructure of the cross section of the aluminum profile of Comparative Example 5 is magnified 100 times. Figure 1 It can be seen that the cross section of the aluminum profile of Example 1 is a small and uniform equiaxed grain structure. After the aluminum profile with this grain structure is processed by CNC and anodized, the color of the oxide film is uniform and delicate, which makes the electronic products have the best aesthetic and decorative effect. Figure 2It can be seen that in Comparative Example 5, due to the unreasonable matching of the extrusion process parameters of the aluminum alloy round bar, the cross-section of the aluminum profile has a coarse grain structure. After CNC processing and anodizing, the aluminum profile with this grain structure will have defects such as structural stripes, spots, and color differences, which seriously affect the color uniformity and texture fineness of the oxide film, and ultimately reduce the beauty and decorative effect of electronic products.

[0136] The present invention is described through embodiments, but does not constitute a limitation of the present invention. With reference to the description of the present invention, other changes to the disclosed embodiments are easy for professionals in this field to think of, and such changes should fall within the scope defined by the claims of the present invention.

Claims

1. A high-strength aluminum profile for electronic product appearance parts, characterized in that: The aluminum profile is composed of the following components in mass percentage: Mg 1.0-1.1%, Si 0.9-1.0%, Cu 0.6-0.7%, Mn 0.2-0.3%, Ti 0.005-0.01%, Fe≤0.1%, and the balance is Al and inevitable impurities, wherein a single inevitable impurity is ≤0.03% and the total impurities are ≤0.1%.

2. A method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 1, characterized in that: The following steps are included in sequence: Step 1: According to the composition of aluminum profiles, aluminum ingots, magnesium ingots, crystalline silicon, aluminum-copper alloy and aluminum-manganese alloy are selected for batching; Step 2: Heat the ingredients in an aluminum melting furnace to melt into aluminum alloy liquid; Step 3: Stir the aluminum alloy liquid in the aluminum melting furnace, and then take samples for online composition detection and adjustment; Step 4: Use nitrogen and flux to spray, refine, degas and remove slag on the aluminum alloy liquid in the aluminum melting furnace; Step 5: The aluminum alloy liquid in the aluminum melting furnace is introduced into the launder, and then aluminum-titanium-carbon rare earth alloy rods are added for online grain refinement treatment; Step 6: The aluminum alloy liquid flows through the degassing box, ceramic filter plate and electromagnetic filter arranged on the launder in sequence for online degassing and slag removal; Step 7: The aluminum alloy liquid flows into the oil-gas sliding semi-continuous casting machine, and semi-continuously casts it into aluminum alloy round bars; Step 8: Perform high-temperature homogenization treatment on the aluminum alloy round bar, and then spray water mist to cool it to room temperature; Step 9: Preheat the aluminum alloy round bar with a gas furnace, and then heat it with an electromagnetic induction furnace at a gradient temperature; Step 10: Extrude the heated aluminum alloy round bar into aluminum profiles, and then cool it to room temperature through water inline; Step 11: The aluminum profiles are stretched, straightened, sawed and framed in sequence; Step 12: Perform aging heat treatment on the aluminum profile, and obtain the high-strength aluminum profile for the electronic product appearance part after cooling to room temperature.

3. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: The flux in step 4 is composed of the following components in mass percentage: Composition: AlCl3 36.12%, LiF 28.37%, CuCO3 21.69%, Ce(NO3)3 13.82%, the amount of the flux used is 0.3-0.4% of the weight of the aluminum alloy liquid.

4. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: In step 5, the aluminum-titanium-carbon rare earth alloy rod is composed of the following components in mass percentage: Ti 5.0%, C 0.1%, La 0.05%, Ce 0.05%, Fe 0.07%, and the balance is Al and unavoidable impurities, wherein the unavoidable impurities are individually ≤0.03% and the total impurities are ≤0.1%.

5. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: The purified gas introduced into the degassing box in step 6 is a mixed gas composed of nitrogen and Freon gas, the volume percentage of Freon gas in the mixed gas is 14-16%, the purity of nitrogen is ≥99.99%, the purity of Freon gas is ≥99.9%, the volume percentage of oxygen content in the mixed gas is ≤0.03%, and the water content is ≤0.3g / m 3 , the flow rate of the mixed gas is 0.8-0.9L / kg aluminum alloy liquid.

6. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: During the semi-continuous casting in step seven, the aluminum alloy liquid temperature is 700-710° C., the compressed air pressure is 0.3-0.4 MPa, the lubricating oil pressure is 0.6-0.7 MPa, the casting speed is 80-120 mm / min, and the cooling water temperature is ≤40° C.

7. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: In step eight, the temperature for high-temperature homogenization treatment of the aluminum alloy round bar is 590-600° C., and the homogenization treatment time is 10-12 hours.

8. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: In step nine, the temperature at which the aluminum alloy round rod is preheated using a gas furnace is 420°C. The temperature gradient heating of the aluminum alloy round rod using an electromagnetic induction furnace is to divide the aluminum alloy round rod into 6 sections on average, and each section is heated with a difference of 10°C. The heating temperature of the head section is 490-500°C, and the heating temperature of the tail section is 440-450°C, so that the aluminum alloy round rod forms a temperature gradient of 50°C from the head section to the tail section.

9. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: During the extrusion in step 10, the upper temperature of the mold is 450-460° C., the extrusion ratio is 30-40, and the advancing speed of the extrusion rod is 3-5 mm / s.

10. The method for preparing a high-strength aluminum profile for an electronic product appearance part according to claim 2, characterized in that: In step 12, the aging temperature of the aluminum profile is 160-170° C., and the aging time is 8-9 hours.

Images