CN109487134B - High-strength aluminum alloy for electronic product appearance part and preparation method thereof - Google Patents
High-strength aluminum alloy for electronic product appearance part and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a high-strength aluminum alloy for electronic product appearance parts and a preparation method thereof, wherein the aluminum alloy comprises the following components in percentage by mass: 4.5-5.5% of Zn, 0.8-1.0% of Mg, 0.3-0.5% of Cu, 0.05-0.15% of Mn, 0.01-0.03% of Y, 0.04-0.06% of Ti, 0.005-0.01% of Sr, less than or equal to 0.1% of Fe, less than or equal to 0.1% of Si, and the balance of Al and inevitable other impurities. The preparation method comprises the steps of smelting and preparing aluminum alloy liquid, blowing and refining in a furnace, refining and modifying on line, degassing and filtering on line, semicontinuous casting, ingot casting homogenization, heating and extruding, quenching on line and artificial aging. The invention refines and changes Fe-rich phase and intercrystalline continuous network MgZn by improving the cleanliness and the structural component uniformity of the aluminum alloy2And the defects of black lines, black points and the like of the oxide film are eliminated, so that the extruded aluminum alloy obtains recrystallized fine isometric grains, the texture stripes and the flower spots of the oxide film are eliminated, and the quality of the oxide film is improved. The aluminum alloy has high strength, good plasticity and excellent oxidation coloring effect, and is suitable for manufacturing appearance structural members of various electronic products.
Description
Technical Field
The invention belongs to the technical field of aluminum alloy processing, and particularly relates to a high-strength aluminum alloy for an electronic product appearance part and a preparation method thereof.
Background
With the development of large screen and light weight of consumer electronic products such as smart phones and tablet computers, high-strength aluminum alloy back plates, middle frames or side frames are urgently needed to improve the bending resistance of the machine body so as to avoid bending and buckling of the machine body when the machine body is pressed, and meanwhile, the aluminum alloy is required to have excellent oxidation coloring effect so as to meet the high decorative requirement of consumers on the appearance parts of the electronic products.
With the coming of the 5G communication era, because the aluminum alloy has a shielding effect on electromagnetic waves, the existing aluminum alloy middle frame and aluminum alloy back plate shell structure cannot meet the transmission requirement of the 5G communication signals of the smart phone, and the aluminum alloy middle frame and glass or ceramic shell structure must be adopted. Therefore, in order to avoid the breakage of glass and ceramic caused by the deformation of the aluminum alloy middle frame when the smart phone falls, high-strength aluminum alloy is urgently needed to manufacture the smart phone middle frame.
The existing aluminum alloy for electronic product appearance parts is mainly Al-Mg-Si series medium-strength aluminum alloy represented by marks of 6101, 6063 and the like, and although the aluminum alloy has excellent extrusion processing performance and oxidation coloring effect, the strength of the aluminum alloy is generally low. Al-Zn-Mg series and Al-Zn-Mg-Cu series aluminum alloys represented by marks of 7003, 7005, 7050, 7075 and the like are heat-treatment-strengthened high-strength aluminum alloys, although the aluminum alloys have the advantage of high strength, the aluminum alloys have poor anodic oxidation effect, the oxide films are easy to have defects of texture stripes, spots, black lines and the like, the glossiness of the oxide films is reduced, the texture is not fine enough, and the high decorative requirements of consumers on the appearance parts of electronic products cannot be met.
Therefore, the existing aluminum alloy for the appearance part of the electronic product and the preparation technology thereof are still in need of improvement and improvement.
Disclosure of Invention
The invention aims to solve the problems and the defects, and provides a high-strength aluminum alloy for electronic product appearance parts and a preparation method thereof.
The technical scheme of the invention is realized as follows:
the invention relates to a high-strength aluminum alloy for electronic product appearance parts, which is characterized in that: the aluminum alloy comprises the following components in percentage by mass: 4.5-5.5% of Zn, 0.8-1.0% of Mg, 0.3-0.5% of Cu, 0.05-0.15% of Mn, 0.01-0.03% of Y, 0.04-0.06% of Ti, 0.005-0.01% of Sr, less than or equal to 0.1% of Fe, less than or equal to 0.1% of Si, the balance of Al and inevitable other impurities, the content of single other impurities is less than or equal to 0.01%, and the total content of other impurities is less than or equal to 0.05%.
The invention relates to a preparation method of a high-strength aluminum alloy for electronic product appearance parts, which is characterized by comprising the following steps of:
the first step is as follows: selecting an aluminum ingot with the purity of 99.9 percent, a zinc ingot with the purity of 99.9 percent, a magnesium ingot with the purity of 99.95 percent, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting an aluminum ingot into a melting furnace, heating and melting at 760-780 ℃, adding a zinc ingot accounting for 4.5-5.5% of the total weight of raw materials, a magnesium ingot accounting for 0.8-1.0%, an AlCu20 alloy accounting for 1.5-2.5%, an AlMn10 alloy accounting for 0.5-1.5% of the total weight of the raw materials and an AlY5 alloy accounting for 0.2-0.6% of the total weight of the raw materials, and stirring and melting the mixture to form an aluminum alloy liquid;
the third step: blowing and refining aluminum alloy liquid in the furnace by using an aluminum alloy refining agent and argon to remove gas and impurities, slagging off and then standing for a certain time;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, and adding AlTi5 alloy accounting for 0.8-1.2% of the total weight of the raw materials and AlSr5 alloy accounting for 0.1-0.2% of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine and a foamed ceramic filter plate which are arranged on a launder to carry out online degassing and filtering treatment;
and a sixth step: semi-continuously casting the aluminum alloy liquid into aluminum alloy ingots;
the seventh step: homogenizing the aluminum alloy cast ingot, and then forcibly cooling the aluminum alloy cast ingot to room temperature by water mist;
eighth step: heating the aluminum alloy cast ingot, then carrying out extrusion forming, and cooling the aluminum alloy cast ingot to room temperature through water;
the ninth step: heating the extruded aluminum alloy for aging treatment, and cooling along with the furnace to obtain the high-strength aluminum alloy for the electronic product appearance piece.
In the third step, the mass of the aluminum alloy refining agent is 0.2-0.5% of the total weight of the raw materials, the purity of argon is more than or equal to 99.9%, the blowing refining time is 10-20 minutes, and the standing time is 30-60 minutes.
In the fifth step, the rotation speed of the graphite rotor of the degasser is 300-400 rpm, the argon flow is 1-2 cubic meters per hour, and the porosity of the foamed ceramic filter plate is 60-90 ppi.
In the sixth step, the casting temperature of the semi-continuous casting is 700-720 ℃, the casting speed is 90-110 mm/min, and the cooling water pressure is 0.3-0.5 MPa.
In the seventh step, the homogenization treatment is to heat the aluminum alloy cast ingot to 450-460 ℃ and preserve heat for 1-2 hours, and then continue to heat to 540-550 ℃ and preserve heat for 6-8 hours.
In the eighth step, the aluminum alloy cast ingot is heated to 420-430 ℃, the extrusion speed is 7-8 m/min, the extrusion ratio is 30-60, and the temperature of the extrusion die is 345-355 ℃.
In the ninth step, the aging treatment is to heat the extruded aluminum alloy to 135-145 ℃ and preserve the temperature for 10-12 hours.
Compared with the prior art, the invention has the following advantages:
(1) the invention solves the contradiction between the strength of the aluminum alloy and the quality of the oxide film by optimally designing the composition of main alloy elements Zn, Mg and Cu of the aluminum alloy, and ensures that the aluminum alloy can obtain high strength and excellent oxidation effect;
(2) according to the invention, the Fe-rich phase is refined and modified by adding Y element, so that the Fe-rich phase is changed into fine uniform particles from a thick needle shape, the defects of black lines, black points and the like of an oxide film caused by the Fe-rich phase are eliminated, and the quality of the oxide film of the aluminum alloy is improved;
(3) the invention uses AlTi5 alloy to replace the traditional Al-Ti-B or Al-Ti-C alloy to refine the grain structure of the aluminum alloy cast ingot and avoid TiB2The particles or TiC particles remain in the aluminum alloy to result in the aluminum alloyThe surface of the aluminum alloy after turning and polishing has the defects of sand holes, streaking and the like, so that the quality of the aluminum alloy oxide film is improved;
(4) the invention adds Sr element on line to form continuous network MgZn between crystal grains2Refining and modifying the phases to make MgZn2The phases are uniformly dispersed in the aluminum alloy to eliminate continuous network MgZn2The problem of grey and dark oxide film is caused, and the glossiness and texture of the oxide film are improved;
(5) according to the invention, by optimally designing the technological parameters of homogenization, heating and extrusion of the aluminum alloy ingot, the aluminum alloy extruded material obtains a fully recrystallized fine uniform equiaxial grain structure, the defects of structure stripes, flower spots and the like of an oxide film are eliminated, and the quality of the oxide film of the aluminum alloy is improved;
(6) the aluminum alloy has the tensile strength of more than 420MPa, the yield strength of more than 380MPa, the elongation after fracture of more than 10 percent and the glossiness value of the anodic oxide film of more than 660GS, has the advantages of high strength, good plasticity, high glossiness of the oxide film, uniform color and fine texture, and meets the requirements of large screen development and light and thin development of electronic products on high-strength aluminum alloy appearance parts.
Drawings
FIG. 1 is a process flow diagram of a preparation method of the high-strength aluminum alloy for the electronic product exterior part.
Detailed Description
In order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings by way of examples and comparative examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention relates to a high-strength aluminum alloy for electronic product appearance parts, which comprises the following components in percentage by mass: 4.5-5.5% of Zn, 0.8-1.0% of Mg, 0.3-0.5% of Cu, 0.05-0.15% of Mn, 0.01-0.03% of Y, 0.04-0.06% of Ti0.04, 0.005-0.01% of Sr, less than or equal to 0.1% of Fe, less than or equal to 0.1% of Si, the balance of Al and inevitable other impurities, the content of single other impurities is less than or equal to 0.01%, and the total content of other impurities is less than or equal to 0.05%.
Zn、MgCu is the main alloying element of the aluminum alloy, and the elements have the solid solution strengthening effect in the aluminum alloy, and Zn and Mg can also form MgZn2Strengthening phase, Cu and Al can precipitate Al2The Cu strengthening phase further enhances the strength of the aluminum alloy. The higher the contents of Zn, Mg and Cu, the higher the strength of the aluminum alloy, but the quality of the oxide film of the aluminum alloy is gradually deteriorated, wherein the oxide film is turbid and cannot be penetrated due to the high Zn content, the oxide film is grayed and darkened due to the high Mg content, and the oxide film is yellowed due to the high Cu content. After systematic research on alloy components, the fact that when the Zn content is less than 4.5%, the Mg content is less than 0.8% or the Cu content is less than 0.3% is found that the strength of the aluminum alloy does not meet the requirements that the tensile strength of an electronic product for an aluminum alloy appearance piece is more than 420MPa and the yield strength of the electronic product is more than 380 MPa. When the Zn content is more than 5.5%, the Mg content is more than 1.0% or the Cu content is more than 0.5%, significant deterioration of the quality of the oxide film of the aluminum alloy is caused. When the Zn content is 4.5-5.5%, the Mg content is 0.8-1.0% and the Cu content is 0.3-0.5%, the contradiction between the aluminum alloy strength and the oxide film quality can be balanced, and the requirements of electronic products on the strength and the oxide film quality of aluminum alloy appearance parts are met.
Mn can form MnAl with Al in the aluminum alloy6The compound dispersed particles have the function of inhibiting the growth of recrystallized grains and refining the recrystallized grains. Another function of Mn in aluminum alloys is to dissolve the impurity element Fe to form (Fe, Mn) Al6The compound reduces the influence of impurity element Fe on the mechanical property of the aluminum alloy. The research result of the inventor shows that the addition of 0.05-0.15% of Mn element can obviously hinder the growth of recrystallized grains and refine the recrystallized grains of the extruded aluminum alloy. However, the content of Mn element should not exceed 0.15%, and coarse MnAl is likely to be formed6The compound dispersion particles can easily cause the defects of black lines, black spots and the like of the aluminum alloy oxide film.
The main function of Y in aluminum alloys is to refine the modified Fe-rich phase. Fe is an inevitable impurity element in the aluminum alloy, and is generally distributed in the aluminum alloy in the form of a coarse acicular Fe-rich phase, and the coarse acicular Fe-rich phase can not only seriously crack the aluminum alloy matrix and reduce the strength and plasticity of the aluminum alloy, but also cause the defects of black lines, black spots and the like of an oxide film. The inventor finds that the element Y has a refining and modifying effect on the Fe-rich phase through a large amount of experimental researches, when 0.01-0.03% of the element Y is added, the Fe-rich phase can be completely inhibited from growing in a needle-shaped direction, the Fe-rich phase is changed into fine and uniform particles from a thick needle shape, the influence of the Fe-rich phase on the strength and plasticity of the aluminum alloy can be eliminated, the defects of black lines, black points and the like of an oxide film caused by the Fe-rich phase can be eliminated, and the quality of the oxide film of the aluminum alloy is obviously improved.
Ti is added into the aluminum alloy liquid in the form of AlTi5 alloy, and mainly has the functions of refining the grain structure of the aluminum alloy cast ingot and improving the structure uniformity of the aluminum alloy cast ingot. The prior art for grain refinement of aluminum alloy cast ingots generally adds Al-Ti-B alloy or Al-Ti-C alloy, and although the Al-Ti-B alloy or the Al-Ti-C alloy has good grain refinement effect on the aluminum alloy cast ingots, the Al-Ti-B alloy contains a large amount of TiB2The particles, Al-Ti-C alloy, contain a large amount of TiC particles, TiB2The particles and TiC particles are hard particles, and a large amount of TiB2The particles or TiC particles are left in the aluminum alloy, so that the surface of the aluminum alloy is easily subjected to sand hole, scribing and other defects after turning and polishing, the quality of an oxide film of the aluminum alloy is further influenced, and the oxide film has black spots, black lines and other defects. Therefore, the aluminum alloy is subjected to online refining treatment by adding 0.8-1.2% of AlTi5 alloy, so that the grain refining requirement of the aluminum alloy cast ingot is met, the defects of sand holes, streaking and the like on the surface of the aluminum alloy after turning and polishing can be avoided, and the quality of an aluminum alloy oxide film is improved.
The main function of Sr in aluminium alloy is to refine continuous network MgZn between modified crystals2And (4) phase(s). The aluminum alloy of the invention has higher Zn content, and Zn and Mg form a large amount of MgZn2Phase, large amount of MgZn2The phases are distributed on grain boundaries in a continuous network shape, which is an important reason for turbidity and impermeability of an aluminum alloy oxide film. In order to solve the problem, the inventor finds that the intercrystalline continuous network MgZn is subjected to intercrystalline continuous network MgZn by adding 0.005-0.01% of Sr element into the aluminum alloy through experimental study2Modifying the phase to make MgZn2The phase is evenly dispersed and distributed in the aluminum alloy, which not only can improve the strength of the aluminum alloy, but also can eliminate continuous reticular MgZn2The phase causes the problem of turbidity of an aluminum alloy oxide film, and the glossiness and texture of the oxide film are obviously improved. However, Sr element is added into the aluminum alloy to easily cause the air suction of the aluminum alloy liquid, so that the addition amount of Sr is not more than 0.01 percent, the AlSr5 alloy needs to be added in a launder on line, the aluminum alloy liquid is subjected to online degassing and filtering and then is semi-continuously cast into ingots immediately, and the air suction of the aluminum alloy liquid caused by the addition of Sr element can be avoided.
Fe is an inevitable main impurity element in an aluminum ingot, and is generally distributed in an aluminum alloy matrix in the form of a coarse acicular Fe-rich phase, so that the coarse acicular Fe-rich phase can not only seriously crack the aluminum alloy matrix and reduce the strength and plasticity of the aluminum alloy, but also cause the defects of black lines, black spots and the like of an oxide film. According to the invention, the aluminum ingot with the purity of 99.9% is selected as a main raw material, the content of Fe is controlled to be less than or equal to 0.1%, the negative influence of Fe impurity elements on the strength and the quality of the oxide film of the aluminum alloy is avoided, and the required mechanical property and the quality of the oxide film of the aluminum alloy are ensured.
Cr, Zr, Sc, Er and the like are micro alloy elements which are frequently added in the traditional aluminum alloy, although the elements can refine the crystal grains of the aluminum alloy and improve the strength of the aluminum alloy, the elements can form coherent or non-coherent aluminide fine dispersed phases with Al, so that the recrystallization of the aluminum alloy is inhibited, the aluminum alloy keeps fibrous crystal grain structures after being extruded, and the fibrous crystal grain structures are the main reasons for defects such as structure stripes, flower spots and the like of an aluminum alloy oxide film. According to the invention, the aluminum ingot with the purity of 99.9% is selected as a main raw material, the single content of impurity elements such as Cr, Zr, Sc, Er and the like is controlled to be less than 0.01%, the total content of the impurity elements is controlled to be less than 0.05%, the inhibition effect of the impurity elements on recrystallization can be eliminated, the aluminum alloy is fully recrystallized during extrusion, a fine uniform equiaxial grain structure is obtained, the defects of texture stripes, flower spots and the like of an oxide film are avoided, and the quality of the oxide film of the aluminum alloy is improved.
The following describes the significance and reasons for selecting the preparation method and the main process parameters of the high-strength aluminum alloy for the electronic product appearance piece according to the invention with reference to fig. 1.
The invention relates to a preparation method of a high-strength aluminum alloy for electronic product appearance parts, which comprises the following steps:
the first step is as follows: selecting 99.9% aluminum ingot, 99.9% zinc ingot, 99.95% magnesium ingot, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting an aluminum ingot into a melting furnace, heating and melting at 760-780 ℃, adding a zinc ingot accounting for 4.5-5.5% of the total weight of raw materials, a magnesium ingot accounting for 0.8-1.0%, an AlCu20 alloy accounting for 1.5-2.5%, an AlMn10 alloy accounting for 0.5-1.5% of the total weight of the raw materials and an AlY5 alloy accounting for 0.2-0.6% of the total weight of the raw materials, and stirring and melting the mixture to form an aluminum alloy liquid;
the third step: blowing and refining aluminum alloy liquid in the furnace by using an aluminum alloy refining agent and argon to remove gas and impurities, slagging off and then standing;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, and adding AlTi5 alloy accounting for 0.8-1.2% of the total weight of the raw materials and AlSr5 alloy accounting for 0.1-0.2% of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine and a foamed ceramic filter plate which are arranged on a launder to carry out online degassing and filtering treatment;
and a sixth step: semi-continuously casting the aluminum alloy liquid into aluminum alloy ingots;
the seventh step: homogenizing the aluminum alloy cast ingot, and then forcibly cooling the aluminum alloy cast ingot to room temperature by water mist;
eighth step: heating the aluminum alloy cast ingot, then carrying out extrusion forming, and cooling the aluminum alloy cast ingot to room temperature through water;
the ninth step: heating the extruded aluminum alloy for aging treatment, and cooling along with the furnace to obtain the high-strength aluminum alloy for the electronic product appearance piece.
Preferably, in the third step, the mass of the aluminum alloy refining agent is 0.2-0.5% of the total weight of the raw materials, the purity of argon is more than or equal to 99.9%, the blowing refining time is 10-20 minutes, and the standing time is 30-60 minutes.
Preferably, the rotation speed of a graphite rotor of the degasser in the fifth step is 300-400 rpm, the argon flow is 1-2 cubic meters per hour, and the porosity of the foamed ceramic filter plate is 60-90 ppi.
The defects of pores, impurities, coarse grains, uneven structure components and the like can reduce the quality of the anodic oxide film of the aluminum alloy, so that the improvement of the purity of the aluminum alloy, the refinement of the grain structure and the elimination of the uneven structure components are basic guarantees for obtaining excellent oxidation effect of the aluminum alloy.
In order to improve the cleanliness of the aluminum alloy, the invention firstly adopts argon with the purity of 99.9 percent to spray and refine aluminum alloy liquid in a furnace for 10-20 minutes, then stands for 30-60 minutes after slagging off, and then uses a degasser and foamed ceramic filtration on a launder to carry out on-line degassing and filtration, and carries out deep purification on the aluminum alloy liquid, so that the gas content of the aluminum alloy liquid is lower than 0.1 ml/100 g of aluminum, the content of non-metallic inclusions PoDFA is lower than 0.06 square millimeter/kg, the cleanliness of the aluminum alloy is greatly increased, and the aluminum alloy is ensured to obtain excellent oxidation effect.
In order to eliminate the influence of coarse grains and coarse Si of the aluminum alloy cast ingot on the quality of an oxide film, the invention adopts the AlTi5 alloy and the AlSr5 alloy to carry out online refining modification treatment on the aluminum alloy liquid, and then carries out semi-continuous casting to form an ingot, thereby meeting the extrusion requirement of the aluminum alloy cast ingot and ensuring that the aluminum alloy can obtain the fine, uniform and equiaxial grain structure requirement of complete recrystallization after extrusion.
Preferably, the casting temperature of the semi-continuous casting in the sixth step is 700-720 ℃, the casting speed is 90-110 mm/min, and the cooling water pressure is 0.3-0.5 MPa.
Preferably, the homogenizing treatment of the aluminum alloy ingot in the seventh step is to heat the aluminum alloy ingot to 450-460 ℃ and preserve heat for 1-2 hours, then continue to heat to 540-550 ℃ and preserve heat for 6-8 hours, and then forcibly cool the aluminum alloy ingot to room temperature by water mist.
The homogenization treatment is intended to eliminate macro-micro segregation of the alloying elements in the ingot, to sufficiently dissolve the alloying elements, and to sufficiently dissolve the coarse intermetallic compounds. The homogenization system of the aluminum alloy ingot casting is systematically researchedThen, the aluminum alloy ingot is heated to 450-460 ℃ for homogenization treatment for 1-2 hours, then is continuously heated to 540-550 ℃ for homogenization treatment for 6-8 hours, and then is forcibly cooled to room temperature by water mist, so that macro-micro segregation of Mg, Si and Cu elements in the ingot can be completely eliminated, and coarse Mg can be enabled to be2Si phase, Al2And intermetallic compounds such as a Cu phase and iron-rich phase are fully dissolved and dissolved, so that the requirement of the electronic product appearance piece on the uniformity of the structure components extruded by the high-strength aluminum alloy cast ingot is met.
Preferably, the heating and then extrusion forming of the aluminum alloy cast ingot in the eighth step is to heat the aluminum alloy cast ingot to 420-430 ℃, then perform extrusion forming under the conditions of extrusion speed of 7-8 m/min, extrusion ratio of 30-60 and mold temperature of 345-355 ℃, and then cool the aluminum alloy cast ingot to room temperature through water.
After the aluminum alloy is extruded, a fibrous grain structure is obtained along the extrusion direction, and the fibrous grain structure is a main reason for defects such as structure stripes, mottling and the like of an aluminum alloy oxide film. Therefore, the aluminum alloy extruded material can obtain a fine uniform equiaxial grain structure which is completely recrystallized, and the defects of structure stripes, mottling and the like of an aluminum alloy oxide film can be eliminated. The applicant discovers that after systematic research on the extrusion process and parameters of the aluminum alloy, the aluminum alloy ingot is heated to 420-430 ℃, extruded and formed under the conditions that the extrusion speed is 7-8 m/min, the extrusion ratio is 30-60 and the mold temperature is 345-355 ℃, and then cooled to room temperature through water, so that the aluminum alloy can be induced to be completely recrystallized, the crystal grains can be prevented from growing, the extruded aluminum alloy can obtain fine and uniform isometric crystal tissues, the requirement of anodic oxidation on the tissue structure of the aluminum alloy is met, the defects of tissue stripes, flower spots and the like of an aluminum alloy oxide film are eliminated, and the high-quality oxidation effect is obtained. If the extrusion process parameters are not in the matching range, a completely recrystallized fine uniform equiaxed grain structure cannot be obtained, and only a fibrous grain structure, or a coarse recrystallized fine grain structure, or a mixed grain structure consisting of fibrous grains and recrystallized grains can be obtained.
Preferably, the heating of the extruded aluminum alloy in the ninth step is performed with aging treatment by heating the extruded aluminum alloy to 135-145 ℃ and preserving the heat for 10-12 hours, and the high-strength aluminum alloy for the electronic product appearance piece is obtained after furnace cooling.
The applicant carries out system research on the artificial aging process of the aluminum alloy extruded material, and finds that when the extruded aluminum alloy is heated to 135-145 ℃ and aged for 10-12 hours and cooled to room temperature along with a furnace, the tensile strength of the aluminum alloy can reach 420MPa, the yield strength of the aluminum alloy can reach more than 380MPa, and the strength requirement of electronic products on aluminum alloy appearance pieces is met. If the aging temperature is lower than 135 ℃ or the aging time is less than 10 hours, the aging effect is insufficient, while if the aging temperature is higher than 145 ℃ or the aging time is more than 12 hours, overaging occurs, and the desired strength of the aluminum alloy is not achieved.
The technical scheme of the invention is further explained by combining specific examples and comparative examples in order to better understand the technical scheme of the invention.
Example 1:
the aluminum alloy comprises the following components in percentage by mass: 4.8 percent of Zn, 0.9 percent of Mg, 0.4 percent of Cu, 0.1 percent of Mn, 0.02 percent of Y, 0.05 percent of Ti, 0.008 percent of Sr, less than or equal to 0.1 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and inevitable other impurities, the single content of the other impurities is less than or equal to 0.01 percent, and the total content is less than or equal to 0.05 percent; the preparation method comprises the following steps:
the first step is as follows: selecting 99.9% aluminum ingot, 99.9% zinc ingot, 99.95% magnesium ingot, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting the aluminum ingot into a melting furnace, heating and melting at 770 ℃, then adding a zinc ingot accounting for 4.8 percent of the total weight of the raw materials, a magnesium ingot accounting for 0.9 percent of the total weight of the raw materials, an AlCu20 alloy accounting for 2 percent of the total weight of the raw materials, an AlMn10 alloy accounting for 1 percent of the total weight of the raw materials and an AlY5 alloy accounting for 0.4 percent of the total weight of the raw materials, and stirring and melting the mixture into an;
the third step: blowing and refining aluminum alloy liquid in the furnace for 15 minutes by using an aluminum alloy refining agent accounting for 0.3 percent of the total weight of the raw materials and argon with the purity of 99.9 percent to remove gas and impurities, and standing for 40 minutes after slagging off;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, adding AlTi5 alloy accounting for 1 percent of the total weight of raw materials and AlSr5 alloy accounting for 0.16 percent of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine with the rotating speed of a graphite rotor of 350 revolutions per minute and the argon flow of 1.5 cubic meters per hour and a foamed ceramic filter plate with the porosity of 80ppi arranged on a launder to carry out online degassing and filtering treatment;
and a sixth step: semi-continuously casting aluminum alloy liquid into aluminum alloy ingots under the conditions that the casting temperature is 710 ℃, the casting speed is 100 mm/min and the cooling water pressure is 0.4 MPa;
the seventh step: heating the aluminum alloy cast ingot to 455 ℃ and preserving heat for 1.5 hours, then continuing to heat to 545 ℃ and preserving heat for 7 hours for homogenization treatment, and then forcibly cooling water mist to room temperature;
eighth step: heating an aluminum alloy cast ingot to 425 ℃, then carrying out extrusion forming under the conditions of extrusion speed of 7.5 m/min, extrusion ratio of 50 and die temperature of 350 ℃, and then cooling to room temperature through water;
the ninth step: heating the extruded aluminum alloy to 140 ℃, preserving heat for 11 hours, carrying out aging treatment, and cooling along with the furnace to obtain the aluminum alloy.
Example 2:
the aluminum alloy comprises the following components in percentage by mass: 4.5 percent of Zn, 1.0 percent of Mg, 0.3 percent of Cu, 0.15 percent of Mn, 0.01 percent of Y, 0.06 percent of Ti, 0.005 percent of Sr, less than or equal to 0.1 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and inevitable other impurities, the single content of the other impurities is less than or equal to 0.01 percent, and the total content is less than or equal to 0.05 percent; the preparation method comprises the following steps:
the first step is as follows: selecting 99.9% aluminum ingot, 99.9% zinc ingot, 99.95% magnesium ingot, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting an aluminum ingot into a melting furnace, heating and melting at 760 ℃, then adding a zinc ingot accounting for 4.5 percent of the total weight of the raw materials, a magnesium ingot accounting for 1.0 percent of the total weight of the raw materials, an AlCu20 alloy accounting for 1.5 percent of the total weight of the raw materials, an AlMn10 alloy accounting for 1.5 percent of the total weight of the raw materials and an AlY5 alloy accounting for 0.2 percent of the total weight of the raw materials, and stirring and melting the mixture into an;
the third step: blowing and refining aluminum alloy liquid in the furnace for 20 minutes by using an aluminum alloy refining agent accounting for 0.2 percent of the total weight of the raw materials and argon with the purity of 99.9 percent to remove gas and impurities, and standing for 30 minutes after slagging off;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, adding AlTi5 alloy accounting for 1.2 percent of the total weight of raw materials and AlSr5 alloy accounting for 0.1 percent of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine with the rotation speed of a graphite rotor being 400 revolutions per minute and the argon flow being 1 cubic meter per hour and a foamed ceramic filter plate with the porosity being 90ppi, and performing online degassing and filtering treatment;
and a sixth step: semi-continuously casting the aluminum alloy liquid into an aluminum alloy ingot under the conditions that the casting temperature is 700 ℃, the casting speed is 110 mm/min and the cooling water pressure is 0.3 MPa;
the seventh step: heating the aluminum alloy cast ingot to 460 ℃ and preserving heat for 1 hour, then continuing to heat to 550 ℃ and preserving heat for 6 hours for homogenization treatment, and then forcibly cooling water mist to room temperature;
eighth step: heating an aluminum alloy cast ingot to 430 ℃, then carrying out extrusion forming under the conditions of extrusion speed of 8 m/min, extrusion ratio of 30 and mold temperature of 345 ℃, and then cooling the aluminum alloy cast ingot to room temperature through water;
the ninth step: heating the extruded aluminum alloy to 145 ℃, preserving heat for 10 hours, carrying out aging treatment, and cooling along with the furnace to obtain the aluminum alloy.
Example 3:
the aluminum alloy comprises the following components in percentage by mass: 5.5 percent of Zn, 0.8 percent of Mg, 0.5 percent of Cu, 0.05 percent of Mn, 0.03 percent of Y, 0.04 percent of Ti, 0.01 percent of Sr, less than or equal to 0.1 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and inevitable other impurities, the single content of the other impurities is less than or equal to 0.01 percent, and the total content is less than or equal to 0.05 percent; the preparation method comprises the following steps:
the first step is as follows: selecting 99.9% aluminum ingot, 99.9% zinc ingot, 99.95% magnesium ingot, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting the aluminum ingot into a melting furnace, heating and melting at 780 ℃, then adding 5.5 percent of zinc ingot, 0.8 percent of magnesium ingot, 2.5 percent of AlCu20 alloy, 0.5 percent of AlMn10 alloy and 0.6 percent of AlY5 alloy which account for the total weight of the raw materials, stirring and melting into aluminum alloy liquid;
the third step: blowing and refining aluminum alloy liquid in the furnace for 10 minutes by using an aluminum alloy refining agent accounting for 0.5 percent of the total weight of the raw materials and argon with the purity of 99.9 percent to remove gas and impurities, and standing for 60 minutes after slagging off;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, adding AlTi5 alloy accounting for 0.8 percent of the total weight of raw materials and AlSr5 alloy accounting for 0.2 percent of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine with the rotation speed of a graphite rotor being 300 revolutions per minute and the argon flow being 2 cubic meters per hour and a foamed ceramic filter plate with the porosity being 60ppi, and performing online degassing and filtering treatment;
and a sixth step: semi-continuously casting the aluminum alloy liquid into an aluminum alloy ingot under the conditions that the casting temperature is 720 ℃, the casting speed is 90 mm/min and the cooling water pressure is 0.5 MPa;
the seventh step: heating the aluminum alloy cast ingot to 450 ℃ and preserving heat for 2 hours, then continuing to heat to 540 ℃ and preserving heat for 8 hours for homogenization treatment, and then forcibly cooling water mist to room temperature;
eighth step: heating an aluminum alloy cast ingot to 420 ℃, then carrying out extrusion forming under the conditions of extrusion speed of 7 m/min, extrusion ratio of 60 and mold temperature of 355 ℃, and then cooling the aluminum alloy cast ingot to room temperature through water;
the ninth step: heating the extruded aluminum alloy to 135 ℃, preserving heat for 12 hours, carrying out aging treatment, and cooling along with the furnace to obtain the aluminum alloy.
Comparative example 1:
the aluminum alloy comprises the following components in percentage by mass: 4.8 percent of Zn, 0.9 percent of Mg, 0.2 percent of Cu, 0.1 percent of Mn, 0.02 percent of Y, 0.05 percent of Ti, 0.008 percent of Sr, less than or equal to 0.1 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and inevitable other impurities, the single content of the other impurities is less than or equal to 0.01 percent, and the total content is less than or equal to 0.05 percent; the preparation method comprises the following steps:
the first step is as follows: selecting 99.9% aluminum ingot, 99.9% zinc ingot, 99.95% magnesium ingot, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting the aluminum ingot into a melting furnace, heating and melting at 770 ℃, then adding a zinc ingot accounting for 4.8 percent of the total weight of the raw materials, a magnesium ingot accounting for 0.9 percent of the total weight of the raw materials, an AlCu20 alloy accounting for 1 percent of the total weight of the raw materials, an AlMn10 alloy accounting for 1 percent of the total weight of the raw materials and an AlY5 alloy accounting for 0.4 percent of the total weight of the raw materials, and stirring and melting the mixture into an;
the third step: blowing and refining aluminum alloy liquid in the furnace for 15 minutes by using an aluminum alloy refining agent accounting for 0.3 percent of the total weight of the raw materials and argon with the purity of 99.9 percent to remove gas and impurities, and standing for 40 minutes after slagging off;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, adding AlTi5 alloy accounting for 1 percent of the total weight of raw materials and AlSr5 alloy accounting for 0.16 percent of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine with the rotating speed of a graphite rotor of 350 revolutions per minute and the argon flow of 1.5 cubic meters per hour and a foamed ceramic filter plate with the porosity of 80ppi arranged on a launder to carry out online degassing and filtering treatment;
and a sixth step: semi-continuously casting aluminum alloy liquid into aluminum alloy ingots under the conditions that the casting temperature is 710 ℃, the casting speed is 100 mm/min and the cooling water pressure is 0.4 MPa;
the seventh step: heating the aluminum alloy cast ingot to 455 ℃ and preserving heat for 1.5 hours, then continuing to heat to 545 ℃ and preserving heat for 7 hours for homogenization treatment, and then forcibly cooling water mist to room temperature;
eighth step: heating an aluminum alloy cast ingot to 425 ℃, then carrying out extrusion forming under the conditions of extrusion speed of 7.5 m/min, extrusion ratio of 50 and die temperature of 350 ℃, and then cooling to room temperature through water;
the ninth step: heating the extruded aluminum alloy to 140 ℃, preserving heat for 11 hours, carrying out aging treatment, and cooling along with the furnace to obtain the aluminum alloy.
Comparative example 2:
the aluminum alloy comprises the following components in percentage by mass: 4.5 percent of Zn, 1.0 percent of Mg, 0.3 percent of Cu, 0.15 percent of Mn, 0.06 percent of Ti, 0.005 percent of Sr, less than or equal to 0.1 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and inevitable other impurities, the single content of other impurities is less than or equal to 0.01 percent, and the total content is less than or equal to 0.05 percent; the preparation method comprises the following steps:
the first step is as follows: selecting 99.9% aluminum ingot, 99.9% zinc ingot, 99.95% magnesium ingot, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting an aluminum ingot into a melting furnace, heating and melting at 760 ℃, adding a zinc ingot accounting for 4.5 percent of the total weight of raw materials, a magnesium ingot accounting for 1.0 percent of the total weight of the raw materials, an AlCu20 alloy accounting for 1.5 percent of the total weight of the raw materials and an AlMn10 alloy accounting for 1.5 percent of the total weight of the raw materials, and stirring and melting the mixture into an aluminum alloy liquid;
the third step: blowing and refining aluminum alloy liquid in the furnace for 20 minutes by using an aluminum alloy refining agent accounting for 0.2 percent of the total weight of the raw materials and argon with the purity of 99.9 percent to remove gas and impurities, and standing for 30 minutes after slagging off;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, adding AlTi5 alloy accounting for 1.2 percent of the total weight of raw materials and AlSr5 alloy accounting for 0.1 percent of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine with the rotation speed of a graphite rotor being 400 revolutions per minute and the argon flow being 1 cubic meter per hour and a foamed ceramic filter plate with the porosity being 90ppi, and performing online degassing and filtering treatment;
and a sixth step: semi-continuously casting the aluminum alloy liquid into an aluminum alloy ingot under the conditions that the casting temperature is 700 ℃, the casting speed is 110 mm/min and the cooling water pressure is 0.3 MPa;
the seventh step: heating the aluminum alloy cast ingot to 460 ℃ and preserving heat for 1 hour, then continuing to heat to 550 ℃ and preserving heat for 6 hours for homogenization treatment, and then forcibly cooling water mist to room temperature;
eighth step: heating an aluminum alloy cast ingot to 430 ℃, then carrying out extrusion forming under the conditions of extrusion speed of 8 m/min, extrusion ratio of 30 and mold temperature of 345 ℃, and then cooling the aluminum alloy cast ingot to room temperature through water;
the ninth step: heating the extruded aluminum alloy to 145 ℃, preserving heat for 10 hours, carrying out aging treatment, and cooling along with the furnace to obtain the aluminum alloy.
Comparative example 3:
the aluminum alloy comprises the following components in percentage by mass: 5.5 percent of Zn, 0.8 percent of Mg, 0.5 percent of Cu, 0.05 percent of Mn, 0.03 percent of Y, 0.04 percent of Ti, less than or equal to 0.1 percent of Fe, less than or equal to 0.1 percent of Si, the balance of Al and inevitable other impurities, the single content of other impurities is less than or equal to 0.01 percent, and the total content is less than or equal to 0.05 percent; the preparation method comprises the following steps:
the first step is as follows: selecting 99.9% aluminum ingot, 99.9% zinc ingot, 99.95% magnesium ingot, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting the aluminum ingot into a melting furnace, heating and melting at 780 ℃, then adding 5.5 percent of zinc ingot, 0.8 percent of magnesium ingot, 2.5 percent of AlCu20 alloy, 0.5 percent of AlMn10 alloy and 0.6 percent of AlY5 alloy which account for the total weight of the raw materials, stirring and melting into aluminum alloy liquid;
the third step: blowing and refining aluminum alloy liquid in the furnace for 10 minutes by using an aluminum alloy refining agent accounting for 0.5 percent of the total weight of the raw materials and argon with the purity of 99.9 percent to remove gas and impurities, and standing for 60 minutes after slagging off;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, and adding AlTi5 alloy accounting for 0.8 percent of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine with the rotation speed of a graphite rotor being 300 revolutions per minute and the argon flow being 2 cubic meters per hour and a foamed ceramic filter plate with the porosity being 60ppi, and performing online degassing and filtering treatment;
and a sixth step: semi-continuously casting the aluminum alloy liquid into an aluminum alloy ingot under the conditions that the casting temperature is 720 ℃, the casting speed is 90 mm/min and the cooling water pressure is 0.5 MPa;
the seventh step: heating the aluminum alloy cast ingot to 450 ℃ and preserving heat for 2 hours, then continuing to heat to 540 ℃ and preserving heat for 8 hours for homogenization treatment, and then forcibly cooling water mist to room temperature;
eighth step: heating an aluminum alloy cast ingot to 420 ℃, then carrying out extrusion forming under the conditions of extrusion speed of 7 m/min, extrusion ratio of 60 and mold temperature of 355 ℃, and then cooling the aluminum alloy cast ingot to room temperature through water;
the ninth step: heating the extruded aluminum alloy to 135 ℃, preserving heat for 12 hours, carrying out aging treatment, and cooling along with the furnace to obtain the aluminum alloy.
According to the national standard GB/T16865-2013 sample and method for tensile test of wrought aluminum, magnesium and alloy processing products thereof, the aluminum alloys prepared in the examples and the comparative examples are processed into standard tensile samples, the standard tensile samples are stretched on an NYP-1980 type electronic tensile testing machine at room temperature, the tensile rate is 2 mm/min, the tensile strength, the yield strength and the elongation after fracture of the aluminum alloy are detected, and the detection results are shown in Table 1.
TABLE 1 tensile mechanical Properties of the aluminum alloys of the examples and comparative examples
| Tensile strength/MPa | Yield strength/MPa | Elongation after break/% | |
| Example 1 | 422.9 | 381.5 | 13.5 |
| Example 2 | 436.1 | 397.2 | 12.3 |
| Example 3 | 451.2 | 406.8 | 10.6 |
| Comparative example 1 | 406.4 | 364.8 | 11.5 |
| Comparative example 2 | 427.1 | 384.1 | 9.8 |
| Comparative example 3 | 440.8 | 397.2 | 8.8 |
Samples were taken from the aluminium alloys prepared in the examples and comparative examples, respectively, and the samples were ground, polished and treated with 70ml HCl +25ml HNO3+5ml HF +100ml H2After the mixed acid solution of O is corroded, the microstructure of the aluminum alloy in the extrusion direction is observed under a WCW-2009 type metallographic microscope, the average size of crystal grains is measured, and the detection result is shown in Table 2.
TABLE 2 metallographic microstructure of aluminium alloys of examples and comparative examples
| Metallographic microstructure | Average grain size/micron | |
| Example 1 | Fine uniform equiaxed grains | 47 |
| Example 2 | Fine uniform equiaxed grains | 36 |
| Example 3 | Fine uniform equiaxed grains | 44 |
| Comparative example 1 | Fine uniform equiaxed grains | 45 |
| Comparative example 2 | Fiber grain + equiaxed grain | 56 |
| Comparative example 3 | Fiber grain + equiaxed grain | 65 |
According to the national standard GB/T12967.4-2014 aluminum and aluminum alloy anode oxide film detection method, the aluminum alloys prepared in the examples and the comparative examples are processed into standard samples, the anode oxidation is carried out under the conditions of 80g/L sulfuric acid, 9g/L citric acid, 7g/L lactic acid, 1.5A/dm2 current density, 10V voltage and 30min oxidation time, the quality of the oxide film of the aluminum alloy is detected, and the detection result is shown in Table 3.
The glossiness of the aluminum alloy oxide films prepared in the examples and the comparative examples at an angle of 60 degrees is tested according to the national standard GB/T20503-2006 method for measuring the specular reflectivity and the specular glossiness of the aluminum and aluminum alloy anodic oxide films, and the test results are shown in Table 3.
TABLE 3 quality of anodic oxide film of aluminum alloys of examples and comparative examples
| Quality of anodic oxide film | Gloss value/GS of oxide film | |
| Example 1 | High glossiness, uniform color, and fine texture | 661 |
| Example 2 | High glossiness, uniform color, and fine texture | 691 |
| Example 3 | High glossiness, uniform color, and fine texture | 682 |
| Comparative example 1 | High glossiness, uniform color, and fine texture | 660 |
| Comparative example 2 | Black lines and dots, low glossiness and poor texture | 581 |
| Comparative example 3 | Turbidity, graying, low gloss and poor texture | 550 |
As can be seen from tables 1 to 3, the tensile strength of the aluminum alloy prepared in examples 1 to 3 is greater than 420MPa, the yield strength is greater than 380MPa, the elongation after fracture is greater than 10%, the metallographic microstructure is fine uniform equiaxial crystal grains which are completely recrystallized, the average size of the crystal grains is less than 50 microns, the anodic oxide film has no defects such as structural stripes, flower spots, black lines, black spots and the like, the glossiness of the oxide film is greater than 660GS, the glossiness of the oxide film is high, and the texture is fine and smooth, which shows that the aluminum alloy prepared by the invention has high strength and excellent anodic oxidation effect.
Comparative example 1 the Cu content of the aluminum alloy was less than 0.3%, resulting in an aluminum alloy having a tensile strength of less than 420MPa and a yield strength of less than 380 MPa. In the comparative example 2, because the Y element is not added, the oxide film has the defects of black lines, black dots and the like, and has poor glossiness and poor texture. Comparative example 3 aluminum alloy since Sr element is not added to MgZn2The modification treatment of the phases leads to the turbidity and the graying of an oxide film of the aluminum alloy, lower glossiness and not fine and smooth texture.
Claims (8)
1. The utility model provides an electronic product outward appearance high strength aluminum alloy for piece which characterized in that: the aluminum alloy comprises the following components in percentage by mass: 4.5-5.5% of Zn, 0.8-1.0% of Mg, 0.3-0.5% of Cu, 0.05-0.15% of Mn, 0.01-0.03% of Y, 0.04-0.06% of Ti, 0.005-0.01% of Sr, less than or equal to 0.1% of Fe, less than or equal to 0.1% of Si, the balance of Al and inevitable other impurities, the content of single other impurities is less than or equal to 0.01%, and the total content of other impurities is less than or equal to 0.05%.
2. A method for preparing a high-strength aluminum alloy for an appearance member of an electronic product according to claim 1, comprising the steps of:
the first step is as follows: selecting an aluminum ingot with the purity of 99.9 percent, a zinc ingot with the purity of 99.9 percent, a magnesium ingot with the purity of 99.95 percent, AlCu20 alloy, AlMn10 alloy, AlY5 alloy, AlTi5 alloy and AlSr5 alloy as raw materials;
the second step is that: putting an aluminum ingot into a melting furnace, heating and melting at 760-780 ℃, adding a zinc ingot accounting for 4.5-5.5% of the total weight of raw materials, a magnesium ingot accounting for 0.8-1.0%, an AlCu20 alloy accounting for 1.5-2.5%, an AlMn10 alloy accounting for 0.5-1.5% of the total weight of the raw materials and an AlY5 alloy accounting for 0.2-0.6% of the total weight of the raw materials, and stirring and melting the mixture to form an aluminum alloy liquid;
the third step: blowing and refining aluminum alloy liquid in the furnace by using an aluminum alloy refining agent and argon to remove gas and impurities, slagging off and then standing for a certain time;
the fourth step: introducing aluminum alloy liquid in the furnace into a launder, and adding AlTi5 alloy accounting for 0.8-1.2% of the total weight of the raw materials and AlSr5 alloy accounting for 0.1-0.2% of the total weight of the raw materials into the aluminum alloy liquid for online refining and modification treatment;
the fifth step: enabling the aluminum alloy liquid to sequentially flow through a degassing machine and a foamed ceramic filter plate which are arranged on a launder to carry out online degassing and filtering treatment;
and a sixth step: semi-continuously casting the aluminum alloy liquid into aluminum alloy ingots;
the seventh step: homogenizing the aluminum alloy cast ingot, and then forcibly cooling the aluminum alloy cast ingot to room temperature by water mist;
eighth step: heating the aluminum alloy cast ingot, then carrying out extrusion forming, and cooling the aluminum alloy cast ingot to room temperature through water;
the ninth step: heating the extruded aluminum alloy for aging treatment, and cooling along with the furnace to obtain the high-strength aluminum alloy for the electronic product appearance piece.
3. The method for producing a high-strength aluminum alloy for an exterior part of an electronic product according to claim 2, wherein: in the third step, the mass of the aluminum alloy refining agent is 0.2-0.5% of the total weight of the raw materials, the purity of argon is more than or equal to 99.9%, the blowing refining time is 10-20 minutes, and the standing time is 30-60 minutes.
4. The method for producing a high-strength aluminum alloy for an exterior part of an electronic product according to claim 2, wherein: in the fifth step, the rotation speed of the graphite rotor of the degasser is 300-400 rpm, the argon flow is 1-2 cubic meters per hour, and the porosity of the foamed ceramic filter plate is 60-90 ppi.
5. The method for producing a high-strength aluminum alloy for an exterior part of an electronic product according to claim 2, wherein: in the sixth step, the casting temperature of the semi-continuous casting is 700-720 ℃, the casting speed is 90-110 mm/min, and the cooling water pressure is 0.3-0.5 MPa.
6. The method for producing a high-strength aluminum alloy for an exterior part of an electronic product according to claim 2, wherein: in the seventh step, the homogenization treatment is to heat the aluminum alloy cast ingot to 450-460 ℃ and preserve heat for 1-2 hours, and then continue to heat to 540-550 ℃ and preserve heat for 6-8 hours.
7. The method for producing a high-strength aluminum alloy for an exterior part of an electronic product according to claim 2, wherein: in the eighth step, the aluminum alloy cast ingot is heated to 420-430 ℃, the extrusion speed is 7-8 m/min, the extrusion ratio is 30-60, and the temperature of the extrusion die is 345-355 ℃.
8. The method for producing a high-strength aluminum alloy for an exterior part of an electronic product according to claim 2, wherein: in the ninth step, the aging treatment is to heat the extruded aluminum alloy to 135-145 ℃ and preserve the temperature for 10-12 hours.
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