Aluminum alloy and preparation method and application thereof

Abstract

The invention discloses an aluminum alloy and a preparation method and application thereof, and the aluminum alloy comprises the following components in percentage by weight: 0.15%-0.30% of Si, less than or equal to 0.15% of Fe, 0.15%-0.25% of Cu, 0.9%-1.1% of Mn, 0.10%-0.30% of Mg, 0.05%-0.10% of Cr, 0.05%-0.10% of Sc, 0.05%-0.10% of Zr, 0.02%-0.05% of Sn and 0.01%-0.03% of Ti. By adjusting the content and the ratio of the main alloy elements to the microelements, the strength of the material is improved on the premise of ensuring the extrusion property and the corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an aluminum alloy and a preparation method and application thereof. Background Art

[0002] Al-Mn series alloys are widely used in the heat exchange industry due to their corrosion resistance and easy processing properties. At the same time, with the expansion of the new energy market, the application of Al-Mn series alloy materials in new energy vehicles is also increasing. However, with the requirement for lightweight new energy vehicles, the requirements for extruded profiles are also getting higher and higher, mainly reflected in the improvement of mechanical properties and the design wall thickness of products is getting thinner and thinner.

[0003] However, the Al-Mn series alloys are non-strengthening alloy materials due to heat treatment. The most direct way to improve strength is through work hardening. However, many products are not easy to cold-process or increase the cold-processing deformation due to their shape or difficulty in cold processing. However, increasing the element content by dispersion and solid solution strengthening will reduce the extrusion processing performance and corrosion resistance of the material. At the same time, Al-Mn alloys for automobiles are corrosion-resistant and easy to process, and are suitable for the extrusion of products such as heat exchangers and component shells. However, the wall thickness of such products is relatively thin. With the extreme requirements of new energy vehicles for lightweight, the wall thickness of extruded profiles is getting thinner and thinner, and the requirements for material strength are increased. If the alloy content is simply increased, the difficulty of extrusion will rise sharply. If the strength is increased by increasing the cold processing deformation, many products cannot be cold-processed, and some cold-processable products cannot increase the deformation indefinitely, which will reduce the corrosion resistance of the material and greatly increase the production cost of the product.

[0004] Therefore, it is necessary to provide an aluminum alloy with high strength, high extrusion processability and corrosion resistance. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention improves the strength, corrosion resistance and extrusion performance of the material while ensuring the extrudability by adjusting the content and ratio of the main alloy elements and trace elements.

[0006] The invention also provides a method for preparing the aluminum alloy.

[0007] The present invention also provides an aluminum profile, the raw material for preparing the aluminum profile includes the above-mentioned aluminum alloy.

[0008] According to one aspect of the present invention, an aluminum alloy is provided, which includes the following components, measured by weight percentage: Si 0.15-0.30%, Fe≤0.15%, Cu 0.15-0.25%, Mn 0.9-1.1%, Mg 0.10-0.30%, Cr 0.05-0.10%, Sc 0.05-0.10%, Zr 0.05-0.10%, Sn 0.02-0.05%, and Ti 0.01-0.03%.

[0009] The aluminum alloy of the present invention has at least the following beneficial effects:

[0010] Cu can increase the dispersion of the precipitated phase in aluminum alloys, and form AlMgSi (Cu) phase together with Mg and Si. At the same time, it also plays a part in the solid solution strengthening effect. Too much Cu will increase the high-temperature flow resistance of the material, reduce the extrusion performance, increase the difficulty of extrusion production, and is not conducive to reducing production costs.

[0011] Mn is the main alloying element in the 3xxx alloy series. It can play a role in solid solution and dispersion strengthening. It can also control the grain structure and inhibit grain growth. However, when the Mn content increases to a certain level, the strength improvement is not obvious, and coarse MnAl compound particles are easily generated, which affects the elongation of the material and is not conducive to the cold processing of the subsequent process. During the homogenization process, Mn forms MnAl phase dispersions of different sizes according to the homogenization process, and these dispersions can effectively prevent the nucleation and growth of grains during hot working or heat treatment, and promote the formation of fibrous structure, or block the growth of recrystallized grains, thereby improving the strength of the material.

[0012] The role of Cr is similar to that of Mn. It can effectively inhibit grain growth. However, the solid solubility of Mn in aluminum is low, and segregation is easy to occur during the casting process. In order to better inhibit recrystallization, a certain amount of Cr is added. However, it is not advisable to add too much. Excessive dispersed phases will increase the rheological stress of the material and greatly increase the difficulty of extrusion of the material.

[0013] Fe is an inevitable harmful impurity in the alloy, but adding Fe to the Al-Mn alloy can make the material obtain finer grains during annealing, so a certain amount of Fe is generally added. However, the product involved in the present invention does not have an annealing process, and it is not desired to obtain a fine recrystallized structure, so the present invention needs to control the Fe content.

[0014] Sc and Zr elements can increase the recrystallization temperature, inhibit recrystallization and refine the recrystallized grains, thereby increasing the strength of the material and improving the welding performance of the material. During the homogenization process, fine metal phase Al 3 Sc and Al 3Zr, when both are added at the same time, nano-scale Al 3 (Sc, Zr) particles, which are formed at about 300℃~425℃, but they will also become coarse due to improper heat treatment. However, since adding Sc alone is quite expensive, it is generally chosen to add Al at the same time. 3 (Sc, Zr), which can reduce the use of Sc and reduce production costs.

[0015] Sn element belongs to the low-temperature phase in aluminum alloy. It can form a Sn-rich nanoscale phase at low temperature. It can be formed preferentially during the homogenization treatment and become the nucleation point of other precipitation phases. It can effectively refine other relatively high-temperature precipitation phases and better play the role of other elements, so there is no need to add more elements to achieve the same purpose.

[0016] Ti is a grain refining element. The present invention adds 0.01% to 0.03% of Ti in order to refine the grain structure during casting and extrusion processing.

[0017] In some embodiments of the present invention, the sum of the mass percentages of the Mg and the Si is 0.25 to 0.58 by weight.

[0018] In aluminum alloys, when Si and Mg elements exist at the same time, Mg 2 As Si and other aging strengthening phases increase, the tensile strength of the alloy increases with the increase of Si and Mg content, but the extrusion difficulty also increases with the increase of Mg and Si content. This alloy is designed with Mg+Si of 0.25-0.58, which can maximize the strength of the material and control the extrusion difficulty of the material. At the same time, Si can also form AlMnSi phase with Mn in Al-Mn alloys. In addition to improving the strength to a certain extent, it can also refine the precipitation of Mn and more effectively control the grain size.

[0019] In some embodiments of the present invention, the composition of the aluminum alloy further includes Al.

[0020] In some embodiments of the present invention, the components of the aluminum alloy include the following components in weight percentage: Si 0.15-0.30%, Fe≤0.15%, Cu 0.15-0.25%, Mn 0.9-1.1%, Mg 0.10-0.30%, Cr0.05-0.10%, Sc 0.05-0.10%, Zr 0.05-0.10%, Sn 0.02-0.05%, Ti 0.01-0.03%, and the balance is aluminum.

[0021] In some embodiments of the present invention, the aluminum alloy further comprises Zn, and the weight percentage of Zn is not higher than 0.05%.

[0022] In some embodiments of the present invention, the components of the aluminum alloy include the following components in weight percentage: Si 0.15-0.30%, Fe≤0.15%, Cu 0.15-0.25%, Mn 0.9-1.1%, Mg 0.10-0.30%, Cr0.05-0.10%, Sc 0.05-0.10%, Zr 0.05-0.10%, Sn 0.02-0.05%, Ti 0.01-0.03%, Zn≤0.05%, and the balance is aluminum.

[0023] According to a second aspect of the present invention, a method for preparing an aluminum alloy is provided, comprising the following steps:

[0024] S1: melting an aluminum ingot, adding a master alloy of the aluminum alloy component, alloying, and refining to obtain an aluminum melt;

[0025] S2: purifying the aluminum melt after standing, and casting to obtain an aluminum alloy ingot;

[0026] S3: homogenizing the aluminum alloy ingot to obtain the aluminum alloy ingot.

[0027] In some embodiments of the present invention, in step S1, the melting temperature is 730-760°C.

[0028] In some embodiments of the present invention, in step S1, the refining temperature is 730-750°C.

[0029] In some embodiments of the present invention, in step S1, the refining is performed under an inert gas atmosphere.

[0030] In some embodiments of the present invention, the inert atmosphere comprises argon.

[0031] In some embodiments of the present invention, in step S1, the refining time is 40 to 50 minutes.

[0032] In some embodiments of the present invention, in step S2, the standing time is 40 to 50 minutes.

[0033] In some embodiments of the present invention, in step S2, the purification includes at least one of degassing purification and filtration purification.

[0034] In some preferred embodiments of the present invention, the degassing and purification is carried out in a box-type degassing device.

[0035] In some preferred embodiments of the present invention, the filtration purification is carried out in an 80-mesh foam ceramic filter plate and an RD tube filter.

[0036] In some embodiments of the present invention, in step S2, the casting temperature is controlled at 690-720°C.

[0037] In some embodiments of the present invention, in step S3, the homogenization step includes a first-stage homogenization process and a second-stage homogenization process.

[0038] In some embodiments of the present invention, the temperature of the first stage homogenization treatment is 300° C. to 350° C., and the time of the first stage homogenization treatment is 3 to 5 hours.

[0039] In some embodiments of the present invention, the temperature of the second stage homogenization treatment is 550° C. to 575° C., and the time of the second stage homogenization treatment is 8 to 10 hours.

[0040] According to a third aspect of the present invention, an aluminum profile is provided, wherein the raw material for preparing the aluminum profile includes the aluminum alloy.

[0041] In some embodiments of the present invention, the method for preparing the aluminum profile comprises the following steps: extruding, quenching, stretching, drawing and then heat treating the aluminum alloy.

[0042] In some embodiments of the present invention, the process further includes sawing the aluminum alloy into suitable lengths before extruding.

[0043] In some embodiments of the present invention, the extrusion temperature of the extrusion step is 480-510° C., and the extrusion ratio of the extrusion step is 50-70.

[0044] In some embodiments of the present invention, the extrusion speed controls the discharge speed to be 6 to 12 m / min.

[0045] In some embodiments of the present invention, the parameters of the quenching step include: entering the quenching cooling device within 30 seconds, and the cooling rate of online quenching is ≥5°C / s.

[0046] In some embodiments of the present invention, the stretching step achieves material straightening and simultaneously removes residual stress in the material.

[0047] In some embodiments of the present invention, during the drawing step, the wall thickness deformation is 20 to 30%.

[0048] In some embodiments of the present invention, the temperature of the heat treatment is 180-255° C., and the holding time of the heat treatment is 2-4 hours.

[0049] In the present invention, the tensile strength of the aluminum alloy in the heat-treated state is b ≥185Mpa, tensile strength of the material after drawing σ b≥205MPa.

[0050] This alloy has good extrusion performance. When extruding thin-walled profiles (1-1.5mm), the breakthrough pressure of the extruder is ≤240Bar.

[0051] The aluminum alloy of the present invention has the same corrosion resistance as the conventional 3003 material.

[0052] The thickness of the coarse-grained layer of the extruded alloy profile of the present invention is ≤100 μm, which is conducive to ensuring the strength, and the grains of the outermost layer are fine, and the coarse-grained structure will not appear after drawing. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is the metallographic structure diagram of the extruded material of Comparative Example 1;

[0054] Figure 2 This is the metallographic structure diagram of the extruded material of Comparative Example 2;

[0055] Figure 3 This is the appearance of the product after the extruded material of comparative example 4 is processed by drawing;

[0056] Figure 4 The appearance of Example 2 and Comparative Example 6 after salt spray corrosion. DETAILED DESCRIPTION

[0057] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0058] Among the raw materials of the present invention:

[0059] Aluminum ingot: Aluminum ingots with a grade of Al99.7 are used, and the mass percentage of Al in the aluminum ingot is more than 99.70%, which meets the standard GB / T 1196-2017 "Aluminum Ingots for Remelting";

[0060] Magnesium ingot: The magnesium ingot is Mg9990, the mass percentage of Mg in the magnesium ingot is above 99.9%, which meets the standard GB / T 3499-2003 "Original Magnesium Ingot";

[0061] Alloy additives: Si is added using AlSi10 master alloy, Cu is pure copper, Cr is AlCr10 master alloy, Mn is AlMn10 master alloy, Sc is AlSc2 master alloy, Zr is AlZr5 master alloy, Ti is added in the form of grain refiner, the quality of the master alloy conforms to GB / T 27677-2017 standard, and the refiner conforms to YS / T 447.1-2011 Alloy wire for grain refinement of aluminum and aluminum alloys Part 1: Aluminum-titanium-boron alloy wire;

[0062] Refining gas: high-purity argon gas is used, with a purity (volume percentage) of ≥99.999%;

[0063] Melting online processing gas: high-purity argon gas is used, and the purity, i.e. the volume percentage, is ≥99.999%.

[0064] Example 1

[0065] This embodiment provides an aluminum alloy and a preparation method thereof. The composition of the aluminum alloy is shown in Table 1. The preparation method comprises the following steps:

[0066] S1: The aluminum ingots in the above raw materials are loaded into a smelting furnace (a regenerative energy-saving furnace), and the temperature in the furnace is controlled at 780°C. After the aluminum ingots are completely melted to form aluminum melt I, AlMn10 is added. After being fully melted, the above magnesium ingots and other intermediate alloys are added, and stirred to melt. The melt is preliminarily alloyed to obtain aluminum melt II, and then a refining agent is added. The amount is 1kg / ton of aluminum melt II, the refining temperature is 730°C, and the refining time is 40 minutes. During the refining process, the obtained aluminum melt is subjected to chemical composition analysis. If the alloy composition is not within the range described in Table 1, the alloy composition is controlled within the range described in Table 1 by fine-tuning the composition; while refining, high-purity argon gas is introduced into the aluminum melt through the air-permeable bricks at the bottom of the furnace for stirring and exhausting, and then slag is skimmed to obtain aluminum melt III, wherein the argon pressure is controlled at 0.05MPa and the flow rate is controlled at 10L / min;

[0067] S2: Perform alloy element analysis on melt III. If the alloy composition is not within the range described in Table 1, fine-tune the composition to control the alloy composition within the range described in Table 1, then let the aluminum melt III stand for 40 minutes, use a degassing device to remove hydrogen, control the hydrogen content of the aluminum melt IV to below 0.15ml / 100g.Al aluminum, use a two-stage filtration system for purification, use 80-mesh foam ceramic filter plate + RD model tubular filtration, and then use a semi-continuous water-cooled casting method. The casting temperature is controlled at 700°C, and an appropriate amount of Al-3Ti-1B refiner is added online at the same time, and cast to obtain an aluminum alloy round ingot;

[0068] S3: The obtained alloy round ingot is heated to 300° C. in a homogenizing heat treatment furnace and kept warm for 3 hours, then heated to 570° C. within 1 hour and kept warm for 8 hours, and then cooled to room temperature with water mist to obtain an aluminum alloy round ingot that meets the requirements of the present invention.

[0069] This embodiment also uses the above aluminum alloy round ingot as a raw material to prepare an aluminum profile, and the specific steps are as follows:

[0070] S4: cutting the aluminum alloy round ingot (aluminum rod) obtained above into 500 mm long, and adding the short rod into an aluminum rod heating furnace, and heating the aluminum rod to 500° C.;

[0071] S5: The aluminum alloy round ingot is loaded into the extruder for extrusion, the extrusion ratio (extrusion coefficient: the ratio of the cross-sectional area of ​​the extrusion barrel cavity to the total cross-sectional area of ​​the extruded product) is 66, the extrusion speed (discharging speed) is 8m / min, and the extrusion outlet temperature is 540°C;

[0072] S6: After the alloy product comes out of the die, it enters the quenching zone within 15 seconds, with a cooling rate of 6℃ / s;

[0073] S7: Stretching deformation: Use a stretching machine to stretch the alloy material, and the stretching amount is controlled at 0.8%.

[0074] S8: Cold working drawing adopts one-pass room temperature drawing, and the wall thickness deformation during the drawing process is 26%;

[0075] S9: Heat treatment process: 180℃ for 3 hours.

[0076] Example 2

[0077] This embodiment provides an aluminum alloy and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the composition of the aluminum alloy is as shown in Table 1, and the preparation method comprises the following steps:

[0078] S1: The aluminum ingots in the above raw materials are loaded into a smelting furnace (a regenerative energy-saving furnace), and the temperature in the furnace is controlled at 780°C. After the aluminum ingots are completely melted to form aluminum melt I, AlMn10 is added. After being fully melted, the above magnesium ingots and other intermediate alloys are added, and stirred to melt. The melt is preliminarily alloyed to obtain aluminum melt II, and then a refining agent is added. The amount is 1kg / ton of aluminum melt II, the refining temperature is 740°C, and the refining time is 40 minutes. During the refining process, the obtained aluminum melt is subjected to chemical composition analysis. If the alloy composition is not within the range described in Table 1, the alloy composition is controlled within the range described in Table 1 by fine-tuning the composition; while refining, high-purity argon gas is introduced into the aluminum melt through the air-permeable bricks at the bottom of the furnace for stirring and exhausting, and then slag is skimmed to obtain aluminum melt III, wherein the argon pressure is controlled at 0.05MPa and the flow rate is controlled at 10L / min;

[0079] S2: Perform alloy element analysis on melt III. If the alloy composition is not within the range described in Table 1, fine-tune the composition to control the alloy composition within the range described in Table 1, then let the aluminum melt III stand for 40 minutes, use a degassing device to remove hydrogen, control the hydrogen content of the aluminum melt IV to below 0.15ml / 100g.Al aluminum, use a two-stage filtration system for purification, use 80-mesh foam ceramic filter plate + RD model tubular filtration, and then use a semi-continuous water-cooled casting method. The casting temperature is controlled at 700°C, and an appropriate amount of Al-3Ti-1B refiner is added online at the same time, and cast to obtain an aluminum alloy round ingot;

[0080] S3: The obtained alloy round ingot is heated to 300° C. in a homogenizing heat treatment furnace and kept warm for 3 hours, then heated to 560° C. within 1 hour and kept warm for 8 hours, and then cooled to room temperature with water mist to obtain an aluminum alloy round ingot that meets the requirements of the present invention.

[0081] This embodiment also uses the above aluminum alloy round ingot as a raw material to prepare an aluminum profile, and the specific steps are as follows:

[0082] S4: cutting the aluminum alloy round ingot (aluminum rod) obtained above into 500 mm long, and adding the short rod into an aluminum rod heating furnace, and heating the aluminum rod to 500° C.;

[0083] S5: The aluminum alloy round ingot is loaded into the extruder for extrusion, the extrusion ratio (extrusion coefficient: the ratio of the cross-sectional area of ​​the extrusion barrel cavity to the total cross-sectional area of ​​the extruded product) is 66, the extrusion speed (discharging speed) is 8m / min, and the extrusion outlet temperature is 540-580°C;

[0084] S6: After the alloy product comes out of the die, it enters the quenching zone within 15 seconds, with a cooling rate of 8℃ / s;

[0085] S7: Stretching deformation: Use a stretching machine to stretch the alloy material, and the stretching amount is controlled at 0.6%.

[0086] S8: Cold working drawing adopts one-pass room temperature drawing, and the wall thickness deformation during the drawing process is 26%;

[0087] S9: Heat treatment process at 200°C for 2 hours.

[0088] Example 3

[0089] This embodiment provides an aluminum alloy and a preparation method thereof. The difference between this embodiment and embodiment 1 is that the composition of the aluminum alloy is as shown in Table 1, and the preparation method comprises the following steps:

[0090] S1: The aluminum ingots in the above raw materials are loaded into a smelting furnace (a regenerative energy-saving furnace), and the temperature in the furnace is controlled at 780°C. After the aluminum ingots are completely melted to form aluminum melt I, AlMn10 is added. After being fully melted, the above magnesium ingots and other intermediate alloys are added, and stirred to melt. The melt is preliminarily alloyed to obtain aluminum melt II, and then a refining agent is added. The amount is 1kg / ton of aluminum melt II, the refining temperature is 750°C, and the refining time is 40 minutes. During the refining process, the obtained aluminum melt is subjected to chemical composition analysis. If the alloy composition is not within the range described in Table 1, the alloy composition is controlled within the range described in Table 1 by fine-tuning the composition; while refining, high-purity argon gas is introduced into the aluminum melt through the air-permeable bricks at the bottom of the furnace for stirring and exhausting, and then slag is skimmed to obtain aluminum melt III, wherein the argon pressure is controlled at 0.05MPa and the flow rate is controlled at 10L / min;

[0091] S2: Perform alloy element analysis on melt III. If the alloy composition is not within the range described in Table 1, fine-tune the composition to control the alloy composition within the range described in step Table 1, then let the aluminum melt III stand for 40 minutes, use a degassing device to remove hydrogen, control the hydrogen content of the aluminum melt IV to below 0.15ml / 100g.Al aluminum, use a two-stage filtration system for purification, use 80-mesh foam ceramic filter plate + RD model tubular filtration, and then use a semi-continuous water-cooled casting method. The casting temperature is controlled at 700°C, and an appropriate amount of Al-3Ti-1B refiner is added online at the same time, and cast to obtain an aluminum alloy round ingot;

[0092] S3: The obtained alloy round ingot is heated to 300° C. in a homogenizing heat treatment furnace and kept warm for 3 hours, then heated to 565° C. within 1 hour and kept warm for 8 hours, and then cooled to room temperature with water mist to obtain an aluminum alloy round ingot that meets the requirements of the present invention.

[0093] This embodiment also uses the above aluminum alloy round ingot as a raw material to prepare an aluminum profile, and the specific steps are as follows:

[0094] S4: cutting the aluminum alloy round ingot (aluminum rod) obtained above into 500 mm long, and adding the short rod into an aluminum rod heating furnace, and heating the aluminum rod to 500° C.;

[0095] S5: The aluminum alloy round ingot is loaded into the extruder for extrusion, the extrusion ratio (extrusion coefficient: the ratio of the cross-sectional area of ​​the extrusion barrel cavity to the total cross-sectional area of ​​the extruded product) is 66, the extrusion speed (discharging speed) is 8m / min, and the extrusion outlet temperature is 540-580°C;

[0096] S6: After the alloy product comes out of the die, it enters the quenching zone within 15 seconds, with a cooling rate of 7℃ / s;

[0097] S7: Stretching deformation: Use a stretching machine to stretch the alloy material, and the stretching amount is controlled at 0.5%.

[0098] S8: Cold working drawing adopts one-pass room temperature drawing, and the wall thickness deformation during the drawing process is 26%;

[0099] S9: Heat treatment process at 190°C for 4 hours.

[0100] Comparative Example 1

[0101] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and the embodiment is that the composition of the aluminum alloy is different, as shown in Table 1, and the other conditions are the same.

[0102] Comparative Example 2

[0103] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and comparative example 1 is that the homogenization process adopted is heating to 300°C and then keeping warm for 3 hours, then heating to 620°C within 1 hour and then keeping warm for 8 hours. The other conditions are the same as those in Example 1.

[0104] Comparative Example 3

[0105] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and Example 1 is that the temperature of the high temperature section of 560°C is changed to 580°C in the homogenization process, and other conditions are the same as those in Example 1.

[0106] Comparative Example 4

[0107] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and Example 1 is that the homogenization process does not include the first low-temperature insulation step, and the temperature is directly increased from room temperature to 560°C within 1 hour. Other conditions are the same as those in Example 1.

[0108] Comparative Example 5

[0109] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and the embodiment is that the composition of the aluminum alloy is different, as shown in Table 1, and the other conditions are the same.

[0110] Comparative Example 6

[0111] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and the embodiment is that the composition of the aluminum alloy is different, as shown in Table 1, and the other conditions are the same.

[0112] Comparative Example 7

[0113] The aluminum alloy composition of this embodiment is the same as that of Embodiment 2. In the homogenization process, the temperature of the high temperature section is changed from 560°C to 540°C. Other conditions are the same as those of Embodiment 1.

[0114] Comparative Example 8

[0115] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and the embodiment is that the composition of the aluminum alloy is different, as shown in Table 1, and the other conditions are the same.

[0116] Comparative Example 9

[0117] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and the embodiment is that the composition of the aluminum alloy is different, as shown in Table 1, and the other conditions are the same.

[0118] Comparative Example 10

[0119] This comparative example provides an aluminum alloy and a preparation method thereof. The difference between this comparative example and the embodiment is that the composition of the aluminum alloy is different, as shown in Table 1, and the other conditions are the same.

[0120] Test example

[0121] The performance test results of the embodiments and comparative examples are shown in Table 1

[0122] Table 1 Aluminum alloy properties

[0123] Mechanical properties test standard: GB / T 228.12021 Tensile test of metallic materials Part 1: Room temperature test method. Extrusion breakthrough pressure: The maximum pressure of the extruder during the extrusion process of the material.

[0124] Tensile strength: The stress corresponding to the maximum force during the tensile test of the material. The tensile strength in Table 2 is the tensile strength of the extruded material without the drawing process (excluding the S8 step).

[0125] Increase cold working tensile strength: The tensile strength of the extruded material after drawing and heat treatment.

[0126] Corrosion resistance test standard: GB / T 10125-2021 Artificial atmosphere corrosion test salt spray corrosion. The corrosion resistance test in the present invention adopts a copper-accelerated acetic acid salt spray test to observe the surface after 24 hours of corrosion, and the absence of pitting corrosion extending into the interior of the metal is used as the qualified standard.

[0127] Table 1 Mass percentage of each component of aluminum alloy (wt%)

[0128]

[0129]

[0130] Table 2 Mechanical properties test results

[0131]

[0132] The chemical composition of Comparative Examples 1 and 2 is conventional 3003 material, without adding Mg, Cr, Sc, Zr, Sn elements. Comparative Example 1 adopts the commonly used high-temperature homogenization process. During the extrusion process, there is no trace element to inhibit recrystallization, forming a recrystallized structure (see Figure 1 ), the extrusion effect is not obvious, resulting in low strength. Secondly, even if the comparative example 2 adopts a special homogenization process, the effect of Mn inhibiting recrystallization alone is not enough to control the grains under large deformation conditions such as extruding thin-walled profiles, resulting in a thick coarse-grained layer, and the same mechanical properties cannot meet the use requirements.

[0133] Compared with Example 1, Comparative Examples 3 and 4 have the same chemical composition, but different homogenization processes. Comparative Example 3 uses a high-temperature homogenization process, which is similar to Comparative Example 2, and the coarse crystals are thicker (see Figure 2 ), the degree of recrystallization increases, resulting in low strength, while Comparative Example 4 does not have a low-temperature precipitation temperature range for heat preservation, so the inhibitory effect of trace elements is weakened, and the strength is reduced. At the same time, the surface grains of the profile cannot be controlled, resulting in the appearance of coarse grains after drawing, affecting the appearance of the product (see Figure 3 ).

[0134] Compared with Example 3, the total amount of Mg and Si elements in Comparative Example 5 reaches 0.68%. Although the strength is significantly improved, the high content of strengthening elements causes an increase in the breakthrough pressure when extruding thin-walled profiles, and the mold is deformed, which greatly increases the production cost.

[0135] Compared with Example 2, the content of Sn element is increased in Comparative Example 6. Since Sn element belongs to the low temperature phase, it is easy to agglomerate or even partially melt at the high temperature at the rear end of the homogenization process. When the content is high, it is easy to cause corrosion in a corrosive environment. When Comparative Example 6 and Example 2 are subjected to salt spray corrosion at the same time, when Example 2 has surface trace corrosion, Comparative Example 6 has already had pitting corrosion deep into the metal (see Figure 4 Comparison), where the salt spray test method meets GB / T 10125-2021 Artificial atmosphere corrosion test salt spray corrosion.

[0136] Compared with Example 2, Comparative Example 7 has the same chemical composition, but adopts a low-temperature homogenization process. At this time, the strength is slightly increased, but the extrusion breakthrough pressure is also increased, which also affects the mold life and increases the production cost. The homogenization treatment temperature of the present invention is coordinated with the chemical composition design to avoid the relatively large grain size caused by insufficient grain refinement.

[0137] Compared with Example 2, Comparative Example 8 increases the content of Cr, Sc, and Zr elements. At this time, the fine dispersed phase formed by the trace elements greatly increases the rheological stress of the material, resulting in the material being unable to be extruded under the existing conditions, which has exceeded the upper limit breakthrough pressure of the extruder.

[0138] Compared with Example 1, Comparative Example 9 does not add Sn element, and there is no Sn element for precipitation nucleation and refinement of other trace elements, resulting in a relatively thick coarse-grained layer, thereby reducing the mechanical properties. At the same time, the grain structure of the outermost layer is also coarse, which is manifested in the subsequent drawing process.

[0139] Compared with Example 1, Comparative Example 10 reduces the content of Mg and Si elements, and the extrusion breakthrough pressure is improved, but the amount of precipitation strengthening phase is reduced, which directly leads to a decrease in mechanical properties.

[0140] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. An aluminum alloy, characterized in that: Calculated by weight percentage, it includes the following components: Si 0.15-0.30%, Fe≤0.15%, Cu 0.15-0.25%, Mn 0.9-1.1%, Mg 0.10-0.30%, Cr 0.05-0.10%, Sc 0.05-0.10%, Zr 0.05-0.10%, Sn 0.02-0.05%, and Ti 0.01-0.03%.

2. The aluminum alloy according to claim 1, characterized in that Calculated by weight percentage, the sum of the mass percentages of the Mg and the Si is 0.25 to 0.

58.

3. The aluminum alloy according to claim 1, characterized in that The aluminum alloy also includes Zn, and the weight percentage of Zn is not higher than 0.05%.

4. A method for preparing an aluminum alloy as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: S1: melting an aluminum ingot, adding a master alloy of the aluminum alloy component, alloying, and refining to obtain an aluminum melt; S2: purifying the aluminum melt after standing, and casting to obtain an aluminum alloy ingot; S3: homogenizing the aluminum alloy ingot to obtain the aluminum alloy ingot.

5. The method for preparing the aluminum alloy according to claim 4, characterized in that: In step S1, the melting temperature is 730-760°C.

6. The method for preparing the aluminum alloy according to claim 4, characterized in that: In step S1, the refining temperature is 730-750°C.

7. The method for preparing the aluminum alloy according to claim 4, characterized in that: In step S3, the homogenization step includes a first-stage homogenization treatment and a second-stage homogenization treatment; and / or, the temperature of the first-stage homogenization treatment is 300°C to 350°C, and the time of the first-stage homogenization treatment is 3 to 5 hours; and / or, the temperature of the second-stage homogenization treatment is 550°C to 575°C, and the time of the second-stage homogenization treatment is 8 to 10 hours.

8. An aluminum profile, characterized in that: The raw material for preparing the aluminum profile comprises the aluminum alloy as claimed in any one of claims 1 to 3.

9. The aluminum profile according to claim 8, characterized in that: The method for preparing the aluminum profile comprises the following steps: extruding, quenching, stretching, drawing and then heat treating the aluminum alloy.

10. The aluminum profile according to claim 9, characterized in that: The extrusion temperature of the extrusion step is 480-510° C., and the extrusion ratio of the extrusion step is 50-70.

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