High-strength aluminum profile and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloys, in particular to a high-strength aluminum profile and a preparation method thereof. The problems that in the prior art, an aluminum profile is low in mechanical property and insufficient in corrosion resistance are solved. Magnesium, silicon, a copper-cerium alloy and a metal erbium element are added into an aluminum ingot, and melting treatment is carried out step by step, so that a smelted alloy is obtained; the smelted alloy is refined through a refining agent, preliminary die casting, segmented extrusion forming and multi-segment aging treatment are combined, the temperature, time and cooling speed of each process are accurately controlled, and an aging treatment profile is obtained; and zinc deposition treatment is carried out, and the high-strength aluminum profile is prepared by optimizing the zinc deposition process and strictly controlling the temperature and time of primary zinc deposition and secondary zinc deposition and the thickness of a zinc deposition layer. Through the adding of all elements and the synergistic effect of process steps and parameters, the strength and corrosion resistance of the aluminum profile are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloys, in particular to a high-strength aluminum profile and a preparation method thereof. Background Art

[0002] Aluminum profiles are widely used in aerospace, automobile manufacturing, construction and many other fields due to their advantages of low density, light weight and good processing performance. However, with the continuous improvement of material performance requirements in various industries, existing aluminum profiles have exposed many deficiencies in mechanical properties and corrosion resistance, which limits their further development and application.

[0003] There are limited means to improve the strength of traditional aluminum profiles. On the one hand, the proportion and type of alloying elements added are relatively simple, making it difficult to give full play to the synergistic strengthening effect between the elements. For example, some aluminum alloys simply add common elements without considering the mutual influence between the elements, resulting in the effects of solid solution strengthening, dispersion strengthening and fine grain strengthening are not obvious, and the tensile strength and yield strength of aluminum profiles cannot be effectively improved. On the other hand, it is difficult to accurately control the distribution and organizational morphology of alloying elements in the existing preparation process. During the smelting process, the elements are unevenly distributed, and segregation is prone to occur, which affects the overall performance of the material. When subjected to large external forces, deformation or even fracture is prone to occur, limiting the further application and development of aluminum profiles in this field.

[0004] In addition, aluminum alloys inevitably contain impurity elements, such as iron and silicon. These impurities form micro-batteries inside the aluminum profiles, accelerating the corrosion process. Traditional refining processes are difficult to effectively remove these impurities, resulting in poor corrosion resistance of aluminum profiles. Secondly, surface treatment technologies such as oxidation treatments form an oxide film with insufficient thickness and density, which cannot effectively block the erosion of corrosive media for a long time. In harsh corrosive environments, due to limited corrosion resistance, the service life is reduced and maintenance costs are increased.

[0005] In summary, the existing aluminum profiles have made corresponding improvements in component ratio and process preparation to improve the comprehensive performance of aluminum profiles. However, there are still problems with insufficient mechanical properties and corrosion resistance, which seriously restricts its demand and application in more fields.

[0006] Therefore, a high-strength aluminum profile and a preparation method thereof are proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a high-strength aluminum profile and a preparation method thereof. By adding magnesium, silicon, copper-cerium alloy, and metal erbium elements to aluminum ingots, and adding them for melting treatment in steps, a smelting alloy is obtained; the smelting alloy is refined by a refining agent, combined with preliminary die-casting, segmented extrusion molding and multi-stage aging treatment, each process temperature, time and cooling rate are accurately controlled to obtain an aging-treated profile; then zinc precipitation treatment is performed, and the temperature, time and thickness of the zinc precipitation layer of the first and second zinc precipitation are strictly controlled by optimizing the zinc precipitation process to prepare a high-strength aluminum profile. The strength and corrosion resistance of the aluminum profile are effectively improved by the synergistic effect of the addition of various elements, process steps and parameters.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing a high-strength aluminum profile. The preparation of the high-strength aluminum profile comprises the following steps:

[0010] S1 completely melts the aluminum ingot, adds 0.8% to 1.5% of metal magnesium, 0.3% to 0.8% of elemental silicon, 1.2% to 2.8% of copper-cerium alloy, 0.4% to 0.6% of metal manganese, 4.2% to 6.5% of metal zinc and 0.1-0.3% of metal erbium, and melts them step by step to obtain a molten alloy;

[0011] S2 adding a refining agent to the molten alloy to obtain a refined alloy;

[0012] S3 adding calcium borate to the refined alloy and die-casting to obtain a casting alloy;

[0013] S4 controls the temperature of the cast alloy in stages and extrudes it to obtain an aluminum profile precursor;

[0014] S5: subjecting the aluminum profile precursor to three-stage aging treatment, controlling the cooling rate to 15-20°C / h to obtain an aging-treated profile;

[0015] S6 treats the aging treated profiles with zinc deposition and washes them to obtain high-strength aluminum profiles; the zinc deposition treatment is divided into primary zinc deposition and secondary zinc deposition; the thickness of the zinc deposition layer in the zinc deposition treatment is 1.4-2.1μm;

[0016] The refining agent is prepared by vacuum calcining potassium chloride, sodium chloride, potassium fluoride, sodium fluoride, metal solution and alumina powder; the particle size of the refining agent is 3-5 mm.

[0017] Preferably, the step-by-step melting includes: placing the aluminum ingot into a resistance furnace, heating it to 680-700°C for complete melting, adding metal magnesium, and reacting at 200r / min for 25min; then adding elemental silicon, heating to 700-720°C, and reacting at 250r / min for 20min; then adding copper-cerium alloy, stirring for 20min; then adding metal manganese, stirring at 680-700°C for 10min; finally adding metal zinc and metal erbium, and stirring at 720-750°C for 10min to obtain a molten alloy.

[0018] Preferably, the preparation of the refining agent comprises the following steps:

[0019] 10-25 parts of potassium chloride, 10-25 parts of sodium chloride, 10-25 parts of potassium fluoride and 10-25 parts of sodium fluoride are crushed in a pulverizer to obtain metal salt particles; scandium oxide and yttrium oxide are added in a molar ratio of 1:1 to a hydrochloric acid solution with a mass concentration of 30%, the temperature is raised to 60°C, and the metal solution is stirred at 300 rpm for 1 hour; 70 parts of metal salt particles are stirred at 500 rpm for 30 minutes to obtain a solid dispersion; 40-60 parts of the metal solution are added to the solid dispersion, and stirring is continued to obtain a mixed material; 40-70 parts of aluminum oxide powder are added to the mixed material to obtain a refining agent precursor; the refining agent precursor is added to a granulator for granulation, and then the refining agent is obtained by vacuum calcination.

[0020] Preferably, the temperature of vacuum calcination is 150-200° C.; the time of vacuum calcination is 1-5 h; and the mass dosage of the refining agent is 0.4%-0.8% of the total mass of the smelted alloy.

[0021] Preferably, the mass dosage of calcium borate in the preparation of the casting alloy is 0.05% of the total mass of the molten alloy; the casting pressure of the die casting is 60MPa, and the holding time of the die casting is 20s; in the segmented temperature control in S4, the temperature of the first segment is 420°C; and the temperature of the second segment is 480°C.

[0022] Preferably, in the three-stage aging treatment in S5, the temperature of the first aging treatment is 480-520°C; the time of the first aging treatment is 2-5h; the temperature of the second aging treatment is 180-220°C; the time of the second aging treatment is 3-8h; the temperature of the third aging treatment is 240-280°C; the time of the third aging treatment is 1-3h.

[0023] Preferably, in S6, the temperature of the first zinc precipitation is 20-50°C; the time of the first zinc precipitation is 60-80s; the temperature of the second zinc precipitation is 10-40°C; the time of the second zinc precipitation is 30-50s.

[0024] The invention provides a high-strength aluminum profile, comprising 0.8% to 1.5% of metal magnesium, 0.3% to 0.8% of elemental silicon, 1.2% to 2.8% of copper-cerium alloy, 0.4% to 0.6% of metal manganese, 4.2% to 6.5% of metal zinc, 0.1% to 0.3% of metal erbium, 0.4% to 0.8% of refining agent and 0.05% of calcium borate, and the balance is aluminum; the high-strength aluminum profile is prepared by any one of the above preparation methods.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention plays a synergistic strengthening role by adding magnesium, silicon, copper-cerium alloy and erbium elements. Magnesium and aluminum form a solid solution to produce solid solution strengthening, which increases the resistance to dislocation movement; silicon and aluminum form a strengthening phase dispersed distribution to hinder dislocation slip; in the copper-cerium alloy, cerium refines the grains, and copper precipitates a strengthening phase through aging strengthening, and the two have a synergistic strengthening effect; metal erbium further refines the grains and improves the organization. At the same time, the properties of each element are used to adjust the order of adding the elements, and rare earth elements are introduced into the refining agent. Under the synergistic effect, the tensile strength is further improved.

[0027] 2. The present invention has a significant effect on improving the yield strength and elongation through the synergistic process of preliminary die-casting, extrusion molding and aging treatment; during the preliminary die-casting, the alloy elements are evenly distributed, and calcium borate is added to refine the grains and improve the density of the material; the extrusion molding controls the temperature, promotes dynamic recrystallization, and improves the uniformity of the structure; the multi-stage aging treatment accurately regulates the precipitation of the strengthening phase, making the strengthening phase small, dispersed and evenly distributed, so that the yield strength and elongation of the aluminum profile are optimized.

[0028] 3. The present invention controls the amount of components in the refining agent, introduces an alumina structure with a high specific surface area, improves the removal effect of impurities and gases during the refining process, and uses rare earth elements in a coordinated manner to utilize their effect on the refinement of aluminum alloy grains, thereby further improving the comprehensive performance of aluminum profiles.

[0029] 4. The present invention can form a dense zinc deposition layer on the surface of the aluminum profile through the synergistic effect of the primary zinc deposition process and the secondary zinc deposition process. By controlling the thickness range of the zinc deposition layer, the bonding ability between the zinc deposition layer and the aluminum profile substrate is improved. Through the auxiliary effect of the refining agent and the introduction of the zinc deposition layer, the corrosion resistance of the aluminum profile is jointly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a process flow chart of the high-strength aluminum profile prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the copper-cerium alloy of the invention, metal copper accounts for 90%-95% of the alloy mass; metal cerium accounts for 5%-10% of the alloy mass.

[0033] See also Figure 1 , Figure 1 The process flow chart of the high-strength aluminum profile prepared in the embodiment of the present invention; the present invention provides a high-strength aluminum profile and a preparation method thereof, and the technical scheme is as follows:

[0034] Example 1

[0035] Preparation of refining agent:

[0036] 20 parts of potassium chloride, 20 parts of sodium chloride, 15 parts of potassium fluoride and 15 parts of sodium fluoride are crushed into a particle size of 100-200 mesh by a pulverizer to obtain metal salt particles; scandium oxide and yttrium oxide are added to a hydrochloric acid solution with a mass concentration of 30% in a molar ratio of 1:1, stirred and dissolved, and deionized water is added to prepare a metal solution with a concentration of 1 mol / L; activated alumina powder with a particle size of 50-100 mesh is added to a drying oven and dried at 150°C for 3 hours; the metal salt particles are 70 parts are put into a high-speed stirrer and stirred at 500 rpm for 30 minutes to obtain a solid dispersion; 50 parts of the metal solution are added to the solid dispersion, and stirring is continued for 20 minutes to obtain a mixture; 60 parts of alumina powder are slowly added to the mixture, the stirring speed is controlled to 300 rpm, and stirring is carried out for 45 minutes to obtain a refining agent precursor; the refining agent precursor is added to a granulator for granulation, and the particle size is controlled to be 2-5 mm; and then the refining agent is obtained by vacuum calcination and drying at 180°C for 3 hours.

[0037] Put the aluminum ingot into a resistance furnace, heat it to 680-700°C for complete melting, add 1.2% metal magnesium, keep the stirring speed at 200r / min, and react for 25min; then add 0.5% elemental silicon, raise the temperature to 700-720°C, adjust the stirring speed to 250r / min, and react for 20min; then add 1.8% copper-cerium alloy, keep the temperature at 700-720°C, and stir for 20min; then add 0.6% manganese, cool down to 680-700°C, and stir for 10min; finally add 5.2% metal zinc and 0.2% metal erbium, maintain the temperature at 720-750°C, and stir for 10min to obtain a molten alloy.

[0038] The mass dosage of the elements is the ratio of the total mass of the molten alloy, and the remainder is aluminum.

[0039] A refining agent is added to the molten alloy, the amount of the refining agent added is 0.5% of the mass of the molten alloy, the refining temperature is controlled at 730° C.-750° C., and the refining time is 30 minutes to obtain a refined alloy; the refined alloy liquid is poured into a specific mold for casting, 0.05% (accounting for 0.05% of the mass of the molten alloy) of dried calcium borate is added, the particle size range is 60-80 μm, the casting temperature is controlled at 700-720° C., the casting pressure is 60 MPa, the pressure holding time is 20 seconds, and the cooling rate is controlled at 15° C. / s to obtain a casting alloy;

[0040] The cast alloy was extruded by controlling the temperature in sections, with an extrusion ratio of 15, a first section temperature of 420°C, and a control time of 20 minutes; the second section temperature was 480°C, and the casting speed was controlled at 10 mm / s to obtain an aluminum profile precursor.

[0041] The aluminum profile precursor was subjected to three-stage aging treatment under nitrogen protection conditions. The first stage of aging treatment was carried out at a temperature of 500°C, kept warm for 3 hours, and a cooling rate of 60°C / s to obtain aluminum profile 1; aluminum profile 1 was heated to 200°C, kept warm for 5 hours, and naturally cooled to obtain aluminum profile 2; aluminum profile 2 was heated to 260°C, kept warm for 2 hours, and a cooling rate of 18°C / h to obtain an aging-treated profile.

[0042] The aging treated profile is treated with zinc by a zinc precipitation agent, the composition of the zinc precipitation agent is 60g / L zinc acetate, 30g / L nickel acetate, 180g / L sodium gluconate, 10g / L 3-amino-1,2,4-triazole, 8g / L ferric nitrate, 100g / L sodium hydroxide, and the balance is methanol. The aging treated profile is treated with zinc precipitation once to obtain a primary zinc precipitation matrix; the primary zinc precipitation temperature is 40°C; the primary zinc precipitation time is 75s; the primary zinc precipitation matrix is ​​added with nitric acid solution for zinc removal treatment, and washed to obtain a zinc removal matrix; the zinc removal matrix is ​​treated with zinc precipitation agent for a second zinc precipitation to obtain a secondary zinc precipitation matrix; the secondary zinc precipitation temperature is 20°C; the secondary zinc precipitation time is 40s; the secondary zinc precipitation matrix is ​​washed with deionized water to obtain a high-strength aluminum profile.

[0043] Examples 2-7 refer to the preparation methods and parameter conditions of Example 1, with the differences shown in Table 1.

[0044] Table 1 Parameter changes of Examples 1-7 Comparative Example 1 refers to Example 1, except that no metallic magnesium is added.

[0045] Comparative Example 2 refers to Example 1, except that no silicon is added.

[0046] Comparative Example 3 refers to Example 1, except that no copper-cerium alloy is added.

[0047] Comparative Example 4 refers to Example 1, except that only metallic copper is added

[0048] Comparative Example 5 refers to Example 1, except that no metallic erbium is added.

[0049] Comparative Example 6 refers to Example 1, except that elemental silicon is added first and then metallic magnesium.

[0050] Comparative Example 7 refers to Example 1, except that the erbium metal is added before the other metals are added.

[0051] Comparative Example 8 refers to Example 1, except that no rare earth element is added to the refining agent.

[0052] Experimental Example 1 Tensile Strength Test

[0053] According to the national standard GB / T 228.1-2021 "Tensile test of metal materials Part 1: Room temperature test method", the tensile strength test of the aluminum profiles prepared in Examples 1-7 and Comparative Examples 1-8 was carried out, and the test results are shown in Table 2.

[0054] Table 2 Tensile strength test of Examples 1-7 and Comparative Examples 1-8

[0055]

[0056]

[0057] From the results in Table 2, it can be seen that in Comparative Examples 1-5, by not adding auxiliary elements, the tensile strength of the aluminum profiles is significantly affected; in the aluminum alloy smelting process, by adding magnesium, silicon, copper-cerium alloy and metal erbium elements, the tensile strength of the aluminum profiles can be significantly increased, because the addition of magnesium can form a solid solution with the aluminum matrix, produce a solid solution strengthening effect, and increase the resistance to dislocation movement; after the addition of elemental silicon, it forms a strengthening phase with the aluminum matrix and is dispersed in the matrix, further hindering dislocation slip; metal erbium refines the grains, improves the alloy structure, and increases the strength; among them, in Comparative Example 4, the tensile strength of the aluminum profile obtained by using only metal copper decreases, and metal cerium has the effect of refining the grains, It can reduce the grain size of aluminum alloy and form a grain boundary structure that hinders the movement of crystal dislocations. Fine grain strengthening can significantly improve the strength and toughness of aluminum alloy. When copper-cerium alloy is not used and only copper is used, the grain refining effect of cerium is missing, the grain of aluminum alloy is relatively large, and the improvement of tensile strength is limited. In addition, copper in copper-cerium alloy is an important element for aging strengthening. During the aging process, strengthening phases will be precipitated to hinder dislocation movement. Although cerium itself does not directly participate in aging strengthening, it improves the distribution and existence form of copper in aluminum alloy through alloying effect, making the aging strengthening effect of copper more sufficient. In comparative example 6, by changing the order of adding magnesium and silicon, the aluminum profile The tensile strength of the profile is significantly affected. The aluminum-magnesium solid solution formed by adding metallic magnesium first provides a stable matrix for the subsequent addition of elements. At the same time, the solid solution strengthening effect of magnesium makes the matrix strength initially improved. After the addition of other elements, they can better combine with the strengthened matrix, further enhancing the strengthening effect. Then, silicon is added, and silicon and metallic aluminum form an aluminum silicide strengthening phase. The aluminum silicide strengthening phase can be more evenly dispersed and effectively hinder the dislocation movement. If silicon is added first, a strengthening phase is formed in the unstrengthened matrix, resulting in uneven distribution of the strengthening phase and reducing the strengthening effect. The premature addition of the rare earth element erbium in Example 7 will also affect the tensile strength of the profile. Metallic erbium has the effect of refining grains and improving The effect of high thermal stability is that adding rare earth elements after strengthening and initial organization formation can further optimize the grain structure, improve high temperature performance and strength. Adding rare earth elements too early will improve the heat resistance of the matrix as a whole, affect the formation of other metal solid solution phases, and affect the grain size. At the same time, adding rare earth elements too early may be consumed by other elements and fail to achieve the effect of grain refinement. In Comparative Example 8, the tensile strength of the aluminum profile obtained by the refining agent without rare earth elements is significantly reduced. The addition of rare earth elements scandium and yttrium can further refine the grains of the aluminum profile. At the same time, adding rare earth elements during the refining process can reduce the amount of rare earth elements used while avoiding loss by other elements during the melting process.The addition of rare earth elements can act as heterogeneous nucleation cores in aluminum alloys, reduce the critical nucleation work of crystal nucleus formation, promote the generation of a large number of fine grains, and increase the grain boundary area, hinder dislocation movement, and improve the strength and toughness of aluminum profiles. At the same time, when added during the refining process, they can form high-melting point compounds with impurity elements in aluminum alloys such as iron and silicon. These compounds will float to the surface of the melt and be removed during the refining process, thereby purifying the alloy and avoiding the formation of alloy impurities. Impurities will form brittle phases or segregation, causing an increase in internal defects in the alloy and forming multiple stress concentration points, which are easy to cause crack propagation when subjected to force, reducing tensile strength. In summary, by using the synergistic effect between magnesium, silicon, copper-cerium alloy and metal erbium elements, the tensile strength of aluminum profiles can be improved by refining grains and forming grain boundary structures. At the same time, the properties of each element are used to adjust the order of element addition, and rare earth elements are introduced into the refining agent. Under the synergistic effect, the tensile strength can be further improved. ;

[0058] Examples 8-12 refer to the preparation methods and parameter conditions of Example 1, with the differences shown in Table 3.

[0059] Table 3 Parameter changes of Example 1, Example 8-12

[0060]

[0061] Comparative Example 8 refers to Example 1, except that no rare earth element is added to the refining agent.

[0062] Comparative Example 9 refers to Example 1, except that the refined alloy is not subjected to high temperature die casting treatment.

[0063] Comparative Example 10 refers to Example 1, except that no segmented extrusion molding process is performed during the extrusion molding process, and the molding temperature is 600°C.

[0064] Comparative Example 11 refers to Example 1, except that no segmented extrusion molding process is performed during the extrusion molding process, and the molding temperature is 400°C.

[0065] Comparative Example 12 refers to Example 1, except that only one aging treatment is performed, and the aging treatment temperature is 500°C.

[0066] Comparative Example 13 refers to Example 1, except that only one aging treatment is performed, and the aging treatment temperature is 200°C.

[0067] Comparative Example 14 refers to Example 1, and during the aging treatment process, the cooling rate of the three-stage aging treatment is 50°C / h.

[0068] Comparative Example 15 refers to Example 1, and during the aging treatment process, the cooling rate of the three-stage aging treatment is 5°C / h.

[0069] Example 2 Yield Strength Test

[0070] According to the national standard GB / T 228.1-2021 "Tensile test of metal materials Part 1: Room temperature test method", the yield strength and elongation of the aluminum profiles prepared in Example 1, Examples 8-12, and Comparative Examples 8-14 were tested, and the test results are shown in Table 4.

[0071] Table 4 Test results of Example 1, Examples 8-12, Comparative Examples 8-15

[0072] Example Yield strength / MPa Elongation / % Example 1 288 20.5 Example 8 285 19.9 Example 9 286 20.3 Example 10 284 19.8 Embodiment 11 285 20.1 Example 12 282 19.4 Comparative Example 8 195 10.2 Comparative Example 9 224 15.3 Comparative Example 10 248 18.2 Comparative Example 11 235 16.8 Comparative Example 12 255 17.2 Comparative Example 13 262 16.5 Comparative Example 14 292 15.8 Comparative Example 15 256 19.8

[0073] From the results in Table 4, it can be seen that in Comparative Example 8, the yield strength and elongation are significantly reduced when no rare earth elements are added to the refining agent. Since the rare earth elements scandium and yttrium can have a synergistic strengthening effect with other alloying elements in the aluminum alloy, the addition of rare earth elements can improve the aging strengthening effect of copper in the aluminum alloy, making the aging precipitation phase of copper finer and more dispersed, and the formed strengthening phase CuAl 2, and other elements such as magnesium, erbium and silicon form a solid solution phase to improve the strength of the aluminum alloy. The lack of rare earth elements makes the synergistic strengthening effect impossible, and the overall strengthening effect of the aluminum alloy is not good; in Example 9, no high-temperature casting treatment is performed; during the initial casting process, the alloy liquid solidifies in the mold, and the die-casting temperature, time and pressure are controlled to make the alloy elements more evenly distributed, reduce component segregation, and make the elements more evenly distributed in the aluminum matrix. The uniform component distribution is conducive to the uniform precipitation of the strengthening phase in the subsequent aging process. At the same time, a trace amount of calcium borate is added as a modifier during the die-casting process, which can increase the number of crystal nuclei and refine the grains. The fine-grained structure can be stretched. Better coordinate deformation, delay the initiation and expansion of cracks, increase the elongation rate, and apply appropriate pressure to make the alloy liquid fill the mold cavity more tightly, reduce defects such as shrinkage holes and pores, increase the density of the material, and further improve the strength and toughness of the aluminum alloy; the results of comparative examples 10-11 show that the temperature has a significant effect on the strength and toughness during the extrusion molding process. Since low temperature is not conducive to the occurrence of dynamic recrystallization, the atomic activity is low, and dislocations are difficult to slide and climb, the aluminum alloy is unevenly deformed during the extrusion process, which is easy to generate large internal stress. The internal stress concentration area is easy to cause cracks, resulting in a decrease in yield strength. In addition, the uneven deformation makes it difficult for the material to be stretched during the stretching process. Uniform load bearing, premature local shrinkage, and reduced elongation; as the temperature rises, the atomic diffusion rate accelerates, the grain boundary migration ability is enhanced, the grains continue to increase, the grains become coarser, the contribution of the grain boundaries to the strength is weakened, the coordination between the coarse grains becomes worse, the strength and toughness decrease, and some alloy elements may be burned at high temperatures, affecting the composition ratio of the alloy, thereby changing the formation and distribution of the strengthening phase, and further reducing the strength and toughness; in Comparative Examples 12-13, one-stage aging treatment significantly reduces the mechanical properties of the aluminum profiles. Since only one aging process is experienced, the precipitation and distribution of the strengthening phase are not uniform and sufficient, and the strengthening phase size is too large to effectively hinder the dislocation movement; The uneven distribution of the strengthening phase leads to insufficient strength in local areas, which easily generates stress concentration when subjected to stress, prematurely triggers crack propagation, and reduces the plastic deformation capacity of aluminum profiles. Multi-stage aging treatment can better regulate the precipitation process of the strengthening phase. During the first stage of aging treatment, a lower temperature can form a large number of uniform nucleation sites, and the alloy elements begin to gather to form some metastable pre-precipitation phases. During the second and third stages of aging treatment, the reasonable control of temperature and time causes the pre-precipitation phase to gradually grow and transform into a stable strengthening phase. These strengthening phases are evenly distributed in the aluminum matrix in a fine and dispersed form, and cooperate with each alloy element to greatly improve the strength and toughness of the aluminum profile.In Comparative Examples 14-15, different cooling temperatures have a significant impact on the mechanical properties of aluminum profiles. Rapid cooling and the supersaturated solid solution formed at high temperature are quickly "frozen", and the alloy elements have no time to precipitate, and are retained in the aluminum matrix in a supersaturated state, causing serious distortion of the aluminum matrix lattice, generating large internal stress, and increasing the resistance to dislocation movement; at the same time, the supersaturated solid solution is in a metastable state, and it is easier to precipitate fine and dispersed strengthening phases. These strengthening phases are dispersed in the matrix, forming a strong barrier to dislocation movement, significantly improving the yield strength of the aluminum alloy. However, during the stretching process, the dislocation movement is strongly hindered, deformation is difficult to proceed uniformly, and it is easy to be localized. Stress concentration occurs in the region, which easily causes the initiation and expansion of cracks, resulting in a decrease in the elongation of the aluminum alloy; on the contrary, the cooling speed is slow, and the alloy elements have enough time to gradually precipitate during the cooling process, but the precipitated strengthening phase is large in size and unevenly distributed, resulting in a large strengthening phase size. Although it is not conducive to the occurrence of stress concentration, the hindering effect on dislocation movement is weakened, and the yield strength is relatively low, which to a certain extent limits the profile from bearing a large load; in summary, through the initial die-casting process, calcium borate is added at the same time to increase the number of crystal nuclei, refine the grains, cooperate with extrusion molding and aging treatment, and control the temperature to improve the strength and toughness of aluminum profiles. ;

[0074] Examples 13-17 refer to the preparation methods and parameter conditions of Example 1, with the differences shown in Table 5.

[0075] Table 5 Parameter changes of Example 1, Examples 13-17

[0076]

[0077]

[0078] Comparative Example 8 refers to Example 1, except that no rare earth element is added to the refining agent.

[0079] Comparative Example 16 refers to Example 1, except that no alumina powder is added to the refining agent.

[0080] Comparative Example 17 refers to Example 1, except that the particle size of the refining agent is 10 mm.

[0081] Comparative Example 18 refers to Example 1, except that the particle size of the refining agent is 1 mm.

[0082] Comparative Example 19 refers to Example 1, except that the mesh size of the aluminum oxide is 200 mesh.

[0083] Comparative Example 20 refers to Example 1, except that the mesh size of the aluminum oxide is 10 mesh.

[0084] Comparative Example 21 refers to Example 1, except that the rare earth element is added directly to the metal particles in the form of oxides without being dissolved by acid.

[0085] Experimental Example 3 Comprehensive Performance Measurement

[0086] The aluminum profiles prepared in Example 1, Examples 13-17, Comparative Example 8, and Comparative Example 16-21 were subjected to tensile strength tests in accordance with the national standard GB / T228.1-2021 "Tensile test of metal materials Part 1: Room temperature test method", and the test results are shown in Table 6; at the same time, the aluminum profiles prepared in the examples were immersed in a 5% sodium chloride aqueous solution and placed at 30°C for 10 days. The corrosion rate of the deposited zinc-aluminum alloy was judged by the change in mass before and after, and the neutral corrosion rate results are shown in Table 6.

[0087] Table 6 Test results of Example 1, Examples 13-17, Comparative Example 8, Comparative Examples 16-21

[0088]

[0089]

[0090] From the results in Table 6, it can be seen that in Comparative Example 8, no rare earth elements are added to the refining agent, and the tensile strength and neutral corrosion resistance of the aluminum profile are significantly reduced. Rare earth elements have the effect of refining grains. In aluminum alloys, fine grains increase the grain boundary area, and the grain boundary can hinder the diffusion of corrosive media. At the same time, rare earth elements and free impurities (such as iron, silicon, etc.) in the aluminum alloy form high-melting point compounds. During the refining process, these compounds will float up and be removed, avoiding the brittle phase or segregation area formed by impurities from becoming the starting point of corrosion, thereby reducing the corrosion resistance of the aluminum profile; without adding rare earth elements, it is difficult to form a dense oxide film on the surface of the aluminum alloy, and the corrosive medium can easily directly enter. It contacts the aluminum alloy matrix, an electrochemical reaction occurs, and the corrosion of the aluminum alloy is accelerated; the results of Example 21 show that adding rare earth elements in the form of a solution can make them more evenly dispersed in the aluminum alloy melt, which is conducive to their full reaction with impurities to form high-melting point compounds and float up for removal; if they are not added in the form of a solution, the rare earth elements may be unevenly distributed in the aluminum alloy, agglomeration may occur, and the role of grain refinement and improvement of alloy properties cannot be fully exerted, resulting in uneven internal structure of the aluminum alloy, and at the same time, the impurity removal of the aluminum alloy is reduced, affecting the corrosion resistance; in Comparative Examples 16 and 19-20, for the addition of alumina and the change of particle size, It obviously affects the comprehensive performance of aluminum profiles; alumina has a large specific surface area and can absorb impurity particles and generated gases in the aluminum alloy melt. If alumina load is not added, these impurities are difficult to be effectively removed and remain inside the aluminum alloy. At the same time, the gases generated in the melt are difficult to be fully adsorbed and discharged. After the aluminum alloy solidifies, these gases may form defects such as pores, which not only reduce the density of the material, but also serve as an intrusion channel for corrosive media, making the aluminum alloy more susceptible to corrosion; in Comparative Examples 17-18, the particle size of the refining agent has a direct impact on the comprehensive performance. If the particle size of the refining agent is too small, its specific surface area increases and it can quickly react with the melt, but The large amount of gas produced in the reaction cannot be quickly absorbed by the alumina in the refining agent, resulting in the formation of pores, reducing the effective bearing area of ​​the aluminum alloy and reducing the tensile strength; the excessively large particle size makes its dispersibility in the aluminum alloy melt worse, and it cannot contact and react with the melt evenly, resulting in poor refining effect, which indirectly affects the corrosion resistance; in summary, by controlling the amount of components in the refining agent, introducing an alumina structure with a high specific surface area, and improving the removal effect of impurities and gases during the refining process, thereby improving the strength and corrosion resistance, and synergistically using rare earth elements and utilizing their effect on the refinement of aluminum alloy grains to further improve the comprehensive performance of aluminum profiles.

[0091] Examples 18-22 refer to the preparation methods and parameter conditions of Example 1, with the differences shown in Table 7.

[0092] Comparative Example 22 refers to Example 1, except that the zinc precipitation process is not added.

[0093] Comparative Example 23 refers to Example 1, except that only one zinc deposition process is used.

[0094] Comparative Example 24 refers to Example 1, except that only the secondary zinc deposition process is used.

[0095] Comparative Example 25 refers to Example 1, except that the parameter conditions of the primary zinc deposition process and the secondary zinc deposition process are interchanged.

[0096] Comparative Example 26 refers to Example 1, except that the thickness of the zinc deposition layer is 0.5 μm.

[0097] Comparative Example 27 refers to Example 1, except that the thickness of the zinc deposition layer is 3 μm.

[0098] Experimental Example 4 Corrosion Resistance Test

[0099] The aluminum profiles prepared in Example 1, Examples 18-22, and Comparative Examples 22-25 were immersed in a 5% sodium chloride aqueous solution and placed at 30°C for 10 days. The corrosion rate of the deposited zinc-aluminum alloy was calculated based on the change in mass before and after. The neutral corrosion rate results are shown in Table 7.

[0100] Table 7 Corrosion resistance test of Example 1, Examples 18-22, Comparative Examples 22-25 It can be seen from the results of Table 7 and the results of Comparative Examples 22-25 that changing the parameters of the zinc deposition process has a significant change in the corrosion resistance of the aluminum profile. The first zinc deposition process requires rapid deposition of complex zinc to increase the thickness of the zinc deposition layer. The second zinc deposition process requires a slow zinc deposition rate to reduce the rapid accumulation of the zinc layer thickness, thereby controlling the growth of zinc atom grains, avoiding the decrease in density caused by rapid accumulation, and maintaining the thickness of the zinc deposition layer while improving the density; if the first zinc deposition temperature is too low, the activity of the metal ions is low, the deposition rate is slow, and it is difficult to form a complete and dense zinc deposition layer on the surface of the aluminum alloy. There are many pores and defects on the surface of the aluminum profile, and the aluminum alloy matrix cannot be effectively isolated from the corrosive medium, reducing the corrosion resistance; excessively high temperature causes the zinc deposition layer crystals to grow too fast and unevenly, resulting in a coarse grain structure, which weakens the bonding force with the aluminum profile and is not conducive to the accumulation of deposited zinc; when the second zinc deposition temperature is low, it is difficult to effectively repair and optimize the first zinc deposition layer, and a dense zinc deposition layer cannot be formed, which makes The improvement of corrosion resistance is limited; however, too high temperature will cause uneven growth of secondary zinc deposition, resulting in local over-thickness or over-thinness, reduced uniformity, and affecting the overall corrosion resistance; the results of comparative examples 26-27 show that when the thickness of the deposited zinc layer is low, the zinc deposition layer cannot provide sufficient protective barrier, and the corrosive medium can easily penetrate the zinc deposition layer and react with the aluminum alloy matrix to reduce the corrosion resistance; too high thickness will produce greater internal stress on the surface of the zinc deposition layer, reducing the bonding force between the zinc deposition layer and the aluminum profile, and when subjected to external force or corrosive medium, the zinc deposition layer is prone to cracking and peeling, which in turn reduces the corrosion resistance of the aluminum profile; in summary, through the synergistic effect of primary zinc deposition and secondary zinc deposition processes, a dense zinc deposition layer can be formed on the surface of the aluminum profile, and by controlling the thickness range of the zinc deposition layer, the bonding ability between the zinc deposition layer and the aluminum profile matrix is ​​improved, and the corrosion resistance is further improved. Combined with the results in Table 6, it can be seen that through the auxiliary effect of the refining agent and the introduction of the synergistic zinc deposition layer, the corrosion resistance of the aluminum profile is jointly improved.

[0101] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-strength aluminum profile, characterized in that: The preparation of the high-strength aluminum profile comprises the following steps: S1: completely melt the aluminum ingot, add 0.8% to 1.5% of metal magnesium, 0.3% to 0.8% of elemental silicon, 1.2% to 2.8% of copper-cerium alloy, 0.4% to 0.6% of metal manganese, 4.2% to 6.5% of metal zinc and 0.1% to 0.3% of metal erbium, and melt in steps to obtain a molten alloy; S2 adding a refining agent to the smelted alloy to obtain a refined alloy; S3 adding calcium borate to the refined alloy and die-casting to obtain a casting alloy; S4: extruding the cast alloy through segmented temperature control to obtain an aluminum profile precursor; S5: subjecting the aluminum profile precursor to three-stage aging treatment, controlling the cooling rate to 15-20° C. / h to obtain an aging-treated profile; S6: subjecting the aging treated profile to zinc deposition treatment and washing to obtain the high-strength aluminum profile; wherein the zinc deposition treatment is divided into primary zinc deposition and secondary zinc deposition; the zinc deposition layer thickness of the zinc deposition treatment is 1.4-2.1 μm; The refining agent is prepared by vacuum calcining potassium chloride, sodium chloride, potassium fluoride, sodium fluoride, metal solution and aluminum oxide powder; the particle size of the refining agent is 3-5 mm.

2. The method for preparing a high-strength aluminum profile according to claim 1, characterized in that: The step-by-step melting includes: placing the aluminum ingot into a resistance furnace, heating it to 680-700° C. for complete melting, adding the metal magnesium, stirring at 200 r / min for reaction for 25 min; then adding the elemental silicon, heating to 700-720° C., and reacting at 250 r / min for 20 min; then adding the copper-cerium alloy, stirring for 20 min; then adding the metal manganese, stirring at 680-700° C. for 10 min; finally adding the metal zinc and the metal erbium, stirring at 720-750° C. for 10 min to obtain the smelted alloy.

3. The method for preparing a high-strength aluminum profile according to claim 1, characterized in that: The preparation of the refining agent comprises the following steps: 10-25 parts of the potassium chloride, 10-25 parts of the sodium chloride, 10-25 parts of the potassium fluoride and 10-25 parts of the sodium fluoride are crushed in a pulverizer to obtain metal salt particles; scandium oxide and yttrium oxide are added in a molar ratio of 1:1 to a hydrochloric acid solution with a mass concentration of 10% to prepare the metal solution; 70 parts of the metal salt particles are stirred at 500 rpm for 30 minutes to obtain a solid dispersion; 40-60 parts of the metal solution are added to the solid dispersion, and stirring is continued to obtain a mixed material; 40-70 parts of the aluminum oxide powder are added to the mixed material to obtain a refining agent precursor; the refining agent precursor is added to a granulator for granulation, and then the refining agent is obtained by vacuum calcination.

4. The method for preparing a high-strength aluminum profile according to claim 3, characterized in that: The temperature of the vacuum calcination is 150-200° C.; the time of the vacuum calcination is 1-5 hours; and the mass dosage of the refining agent is 0.4%-0.8% of the total mass of the smelting alloy.

5. The method for preparing a high-strength aluminum profile according to claim 1, characterized in that: The mass dosage of calcium borate in the preparation of the casting alloy is 0.05% of the total mass of the smelted alloy; the casting pressure of the die casting is 60MPa, and the holding time of the die casting is 20s; in the segmented temperature control in S4, the temperature of the first segment is 420°C; and the temperature of the second segment is 480°C.

6. The method for preparing a high-strength aluminum profile according to claim 1, characterized in that: In the three-stage aging treatment described in S5, the temperature of the first aging treatment is 480-520°C; the time of the first aging treatment is 2-5h; the temperature of the second aging treatment is 180-220°C; the time of the second aging treatment is 3-8h; the temperature of the third aging treatment is 240-280°C; the time of the third aging treatment is 1-3h.

7. The method for preparing a high-strength aluminum profile according to claim 1, characterized in that: In S6, the temperature of the first zinc precipitation is 20-50° C.; the time of the first zinc precipitation is 60-80 seconds; the temperature of the second zinc precipitation is 10-40° C.; the time of the second zinc precipitation is 30-50 seconds.

8. A high-strength aluminum profile, characterized in that: The high-strength aluminum profile comprises 0.8% to 1.5% of metallic magnesium, 0.3% to 0.8% of elemental silicon, 1.2% to 2.8% of copper-cerium alloy, 0.4% to 0.6% of metallic manganese, 4.2% to 6.5% of metallic zinc, 0.1% to 0.3% of metallic erbium, 0.4% to 0.8% of refining agent and 0.05% of calcium borate, with the remainder being aluminum; the high-strength aluminum profile is obtained by the preparation method as described in any one of claims 1 to 7.

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