阅读说明：本技术 一种高强低屈强比6系铝合金及其制备方法 (High-strength low-yield-ratio 6-series aluminum alloy and preparation method thereof ) 是由 黄祯荣 黄铁明 冯永平 池海涛 刘金霞 张建雷 于 2020-11-03 设计创作，主要内容包括：本发明公开了一种高强低屈强比6系铝合金及其制备方法,其组分及质量百分比为：Si1.31-1.4％,Fe0.01～0.45％,Cu0.1-0.2％,Mn0.7-0.85％,Mg0.7-1.0％,Ti0.15％～0.2％,Re≤0.12％,其余为Al。其中,Mg+Si+Mn含量为2.87％-3.1％,Re为Sc和Er其中一种或者两种的组合。制备方法包括以下步骤：1)合金熔炼及铸造；2)均匀化处理；3)挤压机在线淬火；4)时效热处理。本发明制备的铝合金强度高,屈强比低,提高了现有6系合金的安全性与可靠性。(The invention discloses a high-strength low-yield ratio 6 series aluminum alloy and a preparation method thereof, wherein the high-strength low-yield ratio 6 series aluminum alloy comprises the following components in percentage by mass: 1.31 to 1.4 percent of Si, 0.01 to 0.45 percent of Fe0.1 to 0.2 percent of Cu0.7 to 0.85 percent of Mn0.7 to 1.0 percent of Mg0.15 to 0.2 percent of Ti0.12 percent of Re and the balance of Al. Wherein, the content of Mg + Si + Mn is 2.87-3.1%, and Re is one or the combination of Sc and Er. The preparation method comprises the following steps: 1) alloy smelting and casting; 2) carrying out homogenization treatment; 3) online quenching of the extruder; 4) and (4) aging heat treatment. The aluminum alloy prepared by the method has high strength and low yield ratio, and improves the safety and reliability of the existing 6-series alloy.)

1. A high-strength low-yield ratio 6 series aluminum alloy is characterized by comprising the following components in percentage by mass: 1.31-1.4% of Si, 0.01-0.45% of Fe, 0.1-0.2% of Cu, 0.7-0.85% of Mn, 0.7-1.0% of Mg, 0.15-0.2% of Ti, less than or equal to 0.12% of Re, and the balance of Al, wherein the content of Mg, Si and Mn is 2.87-3.1%, and the Re is one or the combination of Sc and Er.

2. The 6-series aluminum alloy with high strength and low yield ratio according to claim 1, wherein the aluminum alloy comprises the following components in percentage by mass: 1.32% of Si, 0.45% of Fe, 0.11% of Cu, 0.85% of Mn, 0.7% of Mg, 0.15% of Ti and the balance of Al.

3. The 6-series aluminum alloy with high strength and low yield ratio according to claim 1, wherein the aluminum alloy comprises the following components in percentage by mass: 1.35% of Si, 0.35% of Fe, 0.11% of Cu, 0.8% of Mn, 0.85% of Mg, 0.15% of Ti, 0.08% of Sc and the balance of Al.

4. The 6-series aluminum alloy with high strength and low yield ratio according to claim 1, wherein the aluminum alloy comprises the following components in percentage by mass: 1.4 percent of Si, 0.25 percent of Fe, 0.11 percent of Cu, 0.7 percent of Mn, 1.0 percent of Mg, 0.2 percent of Ti, 0.04 percent of Sc, 0.08 percent of Er and the balance of Al.

5. A method for preparing the 6-series aluminum alloy with high strength and low yield ratio according to any one of claims 1 to 4, which comprises the following steps:

1) proportioning according to the mass percentage of each component of the aluminum alloy, setting the furnace temperature to 850-890 ℃, sequentially adding a remelted aluminum ingot, aluminum manganese, aluminum iron and aluminum-silicon intermediate alloy, preserving the temperature for a period of time after the remelted aluminum ingot, aluminum manganese, aluminum iron and aluminum-silicon intermediate alloy are completely smelted, and adding a magnesium ingot and an aluminum-rare earth intermediate alloy; stirring when the temperature reaches 810-820 ℃; after the components are qualified, heating the furnace burden to 825-835 ℃, adding a refining agent, and introducing protective gas to perform degassing and deslagging for 5-250 min; standing for 30-45min, introducing the obtained aluminum alloy liquid into a casting disc, adding an Al-Ti-B refiner in the process of introducing the aluminum alloy liquid into the casting disc, controlling the casting speed to be 85-95 mm/min, and casting into ingots to obtain ingots A;

2) placing the ingot A obtained in the step 1) in a homogenizing heat treatment furnace for homogenizing treatment, wherein the homogenizing treatment process parameters are 555-575 ℃, and preserving heat for 18-36 h; after the heat preservation process is finished, cooling with strong wind at the cooling rate of 200-300 ℃/h; when the temperature is reduced to 235-265 ℃, air cooling to room temperature to obtain an ingot B;

3) preheating the aluminum alloy ingot B obtained in the step 2), wherein the preheating temperature is 510-520 ℃, an induction heating device is adopted for the preheating process, the preheating time is not more than 20min, a tool and a die are preheated, the preheating temperature is 470-480 ℃, an extruder is preheated, and the preheating temperature is 440-450 ℃; controlling the outlet speed of the section bar to be 5.0-5.5 m/min, ensuring the temperature of an extrusion outlet to be 530-540 ℃, then cooling the extruded section bar by strong air cooling at the cooling rate of 10-12 ℃/min to 150-180 ℃, and then cooling the section bar to room temperature by air cooling to obtain the aluminum alloy section bar;

4) pre-stretching the aluminum alloy extruded material obtained in the step 3), controlling the stretching rate to be 1.5-2.5%, and carrying out artificial aging treatment after stretching, wherein the aging treatment process is 165-185 ℃, and the heat preservation time is 6-12 h.

6. The method for preparing 6 series aluminum alloy with high strength and low yield ratio as claimed in claim 5, wherein the yield strength of the aluminum alloy is between 280MPa and 300MPa, the tensile strength is between 400MPa and 415MPa, and the yield ratio is between 70% and 75%.

Technical Field

The invention relates to the field of 6-series aluminum alloy, in particular to 6-series aluminum alloy with high strength and low yield ratio and a preparation method thereof.

Background

The 6 series aluminum alloy has wider and wider application field due to good comprehensive performance, the performance requirement on the material is higher and higher, and the yield ratio of most 6 series aluminum alloys is higher. Therefore, when the 6-series aluminum alloy structural member reaches the yield strength and deforms, the material quickly fails, and the safety and reliability of the aluminum alloy structural member are reduced.

The technical scheme mainly aims at the development bottleneck of the current 6-series aluminum alloy, and develops a method which can improve the strength of the 6-series aluminum alloy and can reduce the yield ratio of the alloy.

Disclosure of Invention

Aiming at the defects of the 6-series aluminum alloy, the invention provides the 6-series aluminum alloy with high strength and low yield ratio and the preparation method thereof, firstly, the content range of Si, Mn and Mg elements in the alloy is optimized and designed to carry out the optimization design on the 6-series aluminum alloy, and secondly, the deformation strengthening effect of the alloy is effectively exerted through the precise control of process parameters in the preparation process of the alloy and the coordination of a heat treatment process, so that the 6-series aluminum alloy with high strength and low yield ratio and the preparation method thereof are realized.

The invention is realized by the following technical scheme:

a high-strength low-yield ratio 6 series aluminum alloy comprises the following components in percentage by mass: 1.31-1.4% of Si, 0.01-0.45% of Fe, 0.1-0.2% of Cu, 0.7-0.85% of Mn, 0.7-1.0% of Mg, 0.15-0.2% of Ti, less than or equal to 0.12% of Re, and the balance of Al, wherein the content of Mg, Si and Mn is 2.87-3.1%, and the Re is one or the combination of Sc and Er.

Preferably, the high-strength low-yield-ratio 6-series aluminum alloy comprises the following components in percentage by mass: 1.32% of Si, 0.45% of Fe, 0.11% of Cu, 0.85% of Mn, 0.7% of Mg, 0.15% of Ti and the balance of Al.

Preferably, the high-strength low-yield-ratio 6-series aluminum alloy comprises the following components in percentage by mass: 1.35% of Si, 0.35% of Fe, 0.11% of Cu, 0.8% of Mn, 0.85% of Mg, 0.15% of Ti, 0.08% of Sc and the balance of Al.

Preferably, the high-strength low-yield-ratio 6-series aluminum alloy comprises the following components in percentage by mass: 1.4 percent of Si, 0.25 percent of Fe, 0.11 percent of Cu, 0.7 percent of Mn, 1.0 percent of Mg, 0.2 percent of Ti, 0.04 percent of Sc, 0.08 percent of Er and the balance of Al.

The preparation method of the 6-series aluminum alloy with high strength and low yield ratio comprises the following steps:

1) proportioning according to the mass percentage of each component of the aluminum alloy, setting the furnace temperature to 850-890 ℃, sequentially adding a remelted aluminum ingot, aluminum manganese, aluminum iron and aluminum-silicon intermediate alloy, preserving the temperature for a period of time after the remelted aluminum ingot, aluminum manganese, aluminum iron and aluminum-silicon intermediate alloy are completely smelted, and adding a magnesium ingot and an aluminum-rare earth intermediate alloy; when the temperature is 810-820 ℃, sampling and adjusting the components after stirring; after the components are qualified, heating the furnace burden to 825-835 ℃, adding a refining agent, and introducing protective atmosphere to perform degassing and deslagging for 5-250 min; and standing for 30-45min, introducing the obtained alloy liquid into a casting disc, adding an Al-Ti-B refiner during the introduction of the alloy liquid into the casting disc, controlling the casting speed to be 85-95 mm/min, and casting into ingots to obtain the cast ingots A.

2) Placing the ingot A obtained in the step 1) in a homogenizing heat treatment furnace for homogenizing treatment, wherein the homogenizing treatment process parameters are 555-575 ℃, and preserving heat for 18-36 h; after the heat preservation process is finished, cooling by strong wind at the cooling rate of 200 ℃/h-300 ℃/h; and when the temperature is reduced to 235-265 ℃, air cooling to room temperature to obtain an ingot B.

3) Preheating the ingot B obtained in the step 2) at the preheating temperature of 510-520 ℃, performing the preheating process by using an induction heating device for not more than 20min, preheating a tool and a die at the preheating temperature of 470-480 ℃, and preheating an extruder at the preheating temperature of 440-450 ℃. Controlling the outlet speed of the section bar to be 5.0-5.5 m/min, ensuring the temperature of an extrusion outlet to be 530-540 ℃, then cooling the extrusion section bar by strong air cooling at the cooling rate of 10-12 ℃/s to 150-180 ℃, and then cooling the extrusion section bar to room temperature by air cooling to obtain the aluminum alloy section bar.

4) Pre-stretching the aluminum alloy extruded material obtained in the step 3), controlling the stretching rate to be 1.5-2.5%, and carrying out artificial aging treatment after stretching, wherein the aging treatment process is 165-185 ℃, and the heat preservation time is 6-12 h.

In the alloy formula of the invention, the selected Si element not only forms MgSi precipitation phase with Mg element, but also independently plays a reinforcing role with part of Si to enhance the mechanical property of the alloy. Therefore, the Mg/Si ratio in the alloy is controlled to be 0.5-0.8, wherein the mass content of the alloy element of Si is 1.3-1.4%, and the mass content of the alloy element of Mg is 0.7-1.0%.

Mn is an alloy element which effectively strengthens the mechanical properties of the aluminum alloy. Wherein the Mn element will form AlMn with Al₆The method can effectively play a role of strengthening so as to realize the high strength of the aluminum alloy by matching with Si and Mg elements, so that the content of Mg + Si + Mn is further limited to be 2.87-3.1 percent in the technical scheme.

Firstly, Mg, Si and Mn elements are completely dissolved in an aluminum matrix, so that the homogenization treatment process parameters of the alloy are 555-575 ℃ and the heat preservation is carried out for 18-36 h; after the heat preservation process is finished, cooling by strong wind at the cooling rate of 200 ℃/h-300 ℃/h; and when the temperature is reduced to 235-265 ℃, air cooling to room temperature. The heat preservation process ensures that Mn, Si and Mg elements are completely dissolved back in the matrix, the cooling rate of strong wind is 200-300 ℃/h, the rapid cooling of the cast ingot is ensured, and Mn, Si and Mg cannot be separated out in a second phase form. Meanwhile, the preheating time of the cast rod in the extrusion process is less than 20min, which means that the heating rate of the cast rod is extremely high, and the precipitation of a second phase in the alloy can be effectively reduced. Secondly, the alloy elements are ensured to be fully dissolved in solution in the online quenching process of the alloy, and the working procedure before profile extrusion ensures that main alloy elements Mg, Si and Mn cannot be precipitated in the form of a second phase, so that the outlet speed of the alloy profile is ensured in the online quenching processThe target can be achieved under the condition that the cooling rate of the on-line quenching is matched with other process parameters. Meanwhile, the alloy quenching rate is insufficient due to the fact that the alloy outlet speed is too low, the alloy outlet speed is too high, the surface quality and the dimensional accuracy of the alloy profile are difficult to control, the stress of the profile is released in the preparation process of the alloy profile, and otherwise the profile is buckled and deformed to cause profile rejection. Therefore, the extrusion process and the on-line quenching process are as follows: the outlet speed of the section bar is 5.0m/min-5.5m/min, the temperature of the extrusion outlet is ensured to be 530 ℃ to 540 ℃, and then the extruded section bar is cooled by strong air cooling. Thirdly, ensuring that the size of a precipitated phase in the aging process of the alloy is less than 25 nm. The main principle that precipitated phases can strengthen the alloy is to block dislocation movement, the larger the degree of lattice distortion in the alloy is, the larger the blocking effect is, and when Mg in the alloy is₂After the precipitated phases such as Si grow to 25nm, the coherent degree of the precipitated phases and the aluminum alloy matrix is obviously increased, so that the distortion degree of crystal lattices is reduced. Therefore, it is also very important to properly control the processing after the alloy is quenched. Therefore, the process of the alloy after quenching is set as follows: pre-stretching the extruded material, controlling the stretching rate to be 1.5-2.5%, and carrying out artificial aging treatment after stretching, wherein the aging treatment process is 165-185 ℃, and the heat preservation time is 6-12 h. Therefore, the maximum tensile strength of the alloy can be realized by ensuring the precipitation process in three aspects, and the alloying effect of Mn, Si and Mg in the alloy is fully exerted.

In addition, although the above technical solutions can fully utilize the contribution of the alloy precipitation relative yield strength and tensile strength, the strength of the alloy still cannot be made higher than 400 MPa. Therefore, the alloy structure strengthening effect is required to be exerted, the strength of the alloy is ensured to exceed more than 400MPa, the yield strength of the alloy is not improved, and the yield ratio of the alloy is reduced. Therefore, in the online quenching process of the alloy, the cooling rate is 10 ℃/s-12 ℃/s, and the alloy is cooled to 150-180 ℃ and then cooled by air. Under the process, the texture structure and the structural characteristics in the alloy can not disappear due to the recovery recrystallization process, and the Mn content in the alloy is high and is between 0.7 and 0.85 percent, so that the recrystallization process of the alloy is mainly inhibited besides the strength contribution of Mn element to the alloy, and the structural characteristics of the alloy are retained to the maximum extent after quenching.

In addition, the rare earth element is an important element for strengthening the alloy performance, the comprehensive performance of the alloy can be effectively improved, the addition amount of the rare earth element in the technical scheme is small, the main purpose is to further improve the mechanical property of the alloy, and the rare earth is mainly Sc and Er, so that the cost is greatly reduced relative to the total Sc, and therefore, the cost of the alloy is controllable. And in addition, the Sc and the Er can effectively play a role in grain refinement and dispersion strengthening, and can be matched with Mn element and an online quenching process to finally realize the high-strength performance of the alloy.

The invention has the technical effects that: according to the technical scheme, the optimized preparation of the alloy components is firstly carried out, particularly the contents of Mn, Mg and Si elements are contained, and the contents of Sc and Er elements are also contained, so that the basis of high strength and low yield ratio of the alloy is ensured. Meanwhile, the technological parameters of alloy casting, extrusion and heat treatment are strictly controlled in the preparation process of the alloy section, so that the characteristics of high strength and low yield ratio of the alloy are finally realized, the reliability of alloy application is improved, and the application range of the alloy is expanded.

Detailed Description

The present invention is further illustrated by the following specific examples.

Example 1

A high-strength low-yield ratio 6 series aluminum alloy comprises the following components in percentage by mass: 1.32 percent of Si, 0.45 percent of Fe, 0.11 percent of Cu, 0.85 percent of Mn, 0.7 percent of Mg, 0.15 percent of Ti and the balance of Al, wherein the content of Mg, Si and Mn is 2.87 percent.

The preparation method of the 6-series aluminum alloy with high strength and low yield ratio comprises the following steps:

1) batching according to the mass percentage of the aluminum alloy components, setting the furnace temperature to 850 ℃, sequentially adding a remelted aluminum ingot, aluminum manganese, aluminum iron and aluminum-silicon intermediate alloy, preserving the temperature for a period of time after the remelting of all the components, and adding a magnesium ingot and an aluminum-rare earth intermediate alloy; when the temperature is stabilized to 815 ℃, sampling and adjusting components after stirring; after the components are qualified, heating the furnace burden to 830 ℃, adding a refining agent, and introducing protective atmosphere for degassing and deslagging for 5 min; standing for 30min, introducing the obtained alloy liquid into a casting disc, adding an Al-Ti-B wire refiner in the process of introducing the alloy liquid into the casting disc, controlling the casting speed to be 85mm/min, and casting into ingots to obtain the ingots A.

2) Placing the ingot A obtained in the step 1) in a homogenizing heat treatment furnace for homogenizing treatment, wherein the homogenizing treatment process parameter is 555 ℃, and keeping the temperature for 36 hours; after the heat preservation process is finished, cooling by strong wind at the cooling rate of 200 ℃/h; and when the temperature is reduced to 235 ℃, air cooling to room temperature to obtain an ingot B.

3) Preheating the aluminum alloy ingot B obtained in the step 2), wherein the preheating temperature is 510 ℃, the preheating process is carried out by adopting an induction heating device, the preheating time is not more than 20min, the mold is preheated, the preheating temperature is 470 ℃, the extruder is preheated, and the preheating temperature is 440 ℃. Controlling the outlet speed of the section bar to be 5.0m/min, ensuring the temperature of an extrusion outlet to be 530 ℃, then cooling the extruded section bar by strong air cooling with the cooling rate of 10 ℃/s to 150 ℃, and then cooling the extruded section bar by air to the room temperature to obtain the aluminum alloy section bar.

4) Pre-stretching the aluminum alloy extruded material obtained in the step 3), controlling the stretching rate to be 1.5%, and carrying out artificial aging treatment after stretching, wherein the aging treatment process is 165 ℃, and the heat preservation time is 12 hours.

Example 2

A high-strength low-yield ratio 6 series aluminum alloy comprises the following components in percentage by mass: 1.35 percent of Si, 0.35 percent of Fe, 0.11 percent of Cu, 0.8 percent of Mn, 0.82 percent of Mg, 0.15 percent of Ti, 0.08 percent of Sc and the balance of Al, wherein the content of Mg, Si and Mn is 2.97 percent.

The preparation method of the 6-series aluminum alloy with high strength and low yield ratio comprises the following steps:

1) batching according to the mass percentage of the aluminum alloy components, setting the furnace temperature to 870 ℃, sequentially adding a remelted aluminum ingot, aluminum manganese, aluminum iron and aluminum-silicon intermediate alloy, preserving the temperature for a period of time after the remelting of all the components, and adding a magnesium ingot and an aluminum-rare earth intermediate alloy; when the temperature is up to 810 ℃, sampling and adjusting components after stirring; after the components are qualified, heating the furnace burden to 825 ℃, adding a refining agent, and introducing protective atmosphere to perform degassing and deslagging for 5-250 min; standing for 45min, introducing the obtained alloy liquid into a casting disc, adding an Al-Ti-B wire refiner in the process of introducing the alloy liquid into the casting disc, controlling the casting speed to be 95mm/min, and casting into ingots to obtain the ingots A.

2) Placing the ingot A obtained in the step 1) in a homogenizing heat treatment furnace for homogenizing treatment, wherein the homogenizing treatment process parameter is 575 ℃, and preserving heat for 18 h; after the heat preservation process is finished, cooling by strong wind at the cooling rate of 300 ℃/h; and when the temperature is reduced to 265 ℃, cooling to room temperature in air to obtain an ingot B.

3) Preheating the aluminum alloy ingot B obtained in the step 2), wherein the preheating temperature is 520 ℃, the preheating process is carried out by adopting an induction heating device, the preheating time is not more than 20min, the mold is preheated, the preheating temperature is 480 ℃, the extruder is preheated, and the preheating temperature is 450 ℃. Controlling the outlet speed of the section bar to be 5.0m/min, ensuring the temperature of an extrusion outlet to be 535 ℃, then cooling the extruded section bar by strong air cooling with the cooling rate of 11 ℃/s to 180 ℃, and then cooling the section bar to room temperature by air cooling to obtain the aluminum alloy section bar.

4) Pre-stretching the aluminum alloy extruded material obtained in the step 3), controlling the stretching rate to be 2.5%, and carrying out artificial aging treatment after stretching, wherein the aging treatment process is 185 ℃, and the heat preservation time is 6 hours.

Example 3

A high-strength low-yield ratio 6 series aluminum alloy comprises the following components in percentage by mass: 1.4 percent of Si, 0.25 percent of Fe, 0.11 percent of Cu, 0.7 percent of Mn, 1.0 percent of Mg, 0.2 percent of Ti, 0.04 percent of Sc, 0.08 percent of Er and the balance of Al, wherein the content of Mg, Si and Mn is 3.1 percent.

The preparation method of the 6-series aluminum alloy with high strength and low yield ratio comprises the following steps:

1) proportioning according to the mass percentage of the components of the aluminum alloy, setting the furnace temperature to 890 ℃, sequentially adding a remelted aluminum ingot, aluminum manganese, aluminum iron and aluminum-silicon intermediate alloy, preserving the temperature for a period of time after the remelting of all the components, and adding a magnesium ingot and an aluminum-rare earth intermediate alloy; when the temperature is 820 ℃, sampling and adjusting components after stirring; after the components are qualified, heating the furnace burden to 835 ℃, adding a refining agent, and introducing protective atmosphere for degassing and deslagging for 5-250 min; and standing for 40min, introducing the obtained alloy liquid into a casting disc, adding an Al-Ti-B wire refiner in the process of introducing the alloy liquid into the casting disc, controlling the casting speed to be 90mm/min, and casting into ingots to obtain the ingots A.

2) Placing the ingot A obtained in the step 1) in a homogenizing heat treatment furnace for homogenizing treatment, wherein the homogenizing treatment process parameter is 565 ℃, and preserving heat for 22 hours; after the heat preservation process is finished, cooling with strong wind at a cooling rate of 250 ℃/h; and when the temperature is reduced to the range of 250 ℃, air cooling to room temperature to obtain an ingot B.

3) Preheating the aluminum alloy ingot B obtained in the step 2), wherein the preheating temperature is 515 ℃, the preheating process is carried out by adopting an induction heating device, the preheating time is not more than 20min, the tool and the die are preheated, the preheating temperature is 475 ℃, and the extruder is preheated, and the preheating temperature is 445 ℃. Controlling the outlet speed of the section bar to be 5.5m/min, ensuring the temperature of an extrusion outlet to be 540 ℃, then cooling the extruded section bar by strong air cooling with the cooling rate of 12 ℃/s to 165 ℃, and then cooling the extruded section bar by air to room temperature to obtain the aluminum alloy section bar.

4) Pre-stretching the aluminum alloy extruded material obtained in the step 3), controlling the stretching rate to be 2%, and carrying out artificial aging treatment after stretching, wherein the aging treatment process is 175 ℃, and the heat preservation time is 9 hours.

Comparative example 1

In comparison with example 1, comparative example 1 has an Mn element content of 0.6% and an Mg + Si + Mn content of 2.62%. The rest is the same as in example 1.

Comparative example 2

Compared with the example 2, the preheating temperature of the cast ingot in the step 3) in the comparative example 2 is 490 ℃, the preheating temperature of the tool and the die is 450 ℃, the preheating temperature of the extruder is 420 ℃, and the outlet speed of the section bar is controlled to be 3.0m/min, and the rest is the same as the example 2.

Comparative example 3

Compared with the example 3, the aging treatment process of the step 4) in the comparative example 3 is 200 ℃, the holding time is 15h, and the rest is the same as the example 3.

Comparative example 4

Compared with the example 3, the temperature of the furnace charge in the step 1) of the comparative example 4 is raised to 805 ℃, then the refining agent is added, and the rest is the same as the example 3.

The following table shows the comparison of tensile strength, yield strength and yield ratio of the aluminum alloy sections prepared in examples 1 to 3 of the present invention and comparative examples 1 to 4, respectively, and the results are as follows:

serial number	Tensile strength/MPa	Yield strength MPa	Yield ratio/%
				Example 1	402	281	72.4
Example 2	411	297	72.3
				Example 3	415	298	71.8
Comparative example 1	328	276	84.1
				Comparative example 2	337	282	83.7
Comparative example 3	335	285	85.1
				Comparative example 4	331	295	89.1

The aluminum alloy sections obtained in the embodiments 1 to 3 have the tensile strength of more than 400MPa and the yield ratio is low, so that the rationality of the component design and the preparation process of the aluminum alloy sections is reflected, and particularly, compared with the existing 6-series aluminum alloy material, the aluminum alloy sections have very obvious advantages. Compared with the embodiment 1, the content of Mn element in the comparative example 1 is reduced, and the content of Mg + Si + Mn is lower than 2.87%, and the final result shows that the yield strength of the aluminum alloy section prepared by the method is not large, but the tensile strength is obviously lower, so that the yield ratio is higher, which shows that the content of Mn element is too low, and the Mn element cannot be well matched with Mg and Si element to effectively exert the alloy strengthening effect. Compared with example 2, the extrusion temperature of the profile in comparative example 2 is reduced, the extrusion outlet speed is controlled to be 3.0m/min, and the result after extrusion aging shows that: the strength of the aluminum alloy section prepared by the method is not high, because the outlet temperature of the section is not high due to the low extrusion outlet speed, and further, the alloy elements are not sufficiently dissolved in the online quenching process, so that the alloy strength is not high. Compared with the embodiment 3, the aging process in the comparative example 3 is 200 ℃, the temperature is kept for 15h, and the performance result shows that under the aging system, the precipitated phase in the alloy grows and is larger than 25nm, the coherent degree of the precipitated phase and the aluminum alloy matrix is increased, so that the lattice distortion degree is reduced, the obstruction of dislocation motion is reduced, and the alloying effect of Mn, Si and Mg in the alloy is not fully exerted. Compared with example 3, in comparative example 4, the casting temperature is reduced, the strength of the alloy is greatly reduced, and the yield ratio is obviously increased, because the reduction of the casting temperature causes the increase of the melt viscosity, the deterioration of feeding conditions, the increase of defects such as looseness, oxidation film and the like, and the performance of the alloy is affected.

The comparison result shows that the 6-series aluminum alloy material with high strength and low yield ratio prepared by the method is a material with higher safety and wider application range.

The above description is only for the preferred embodiment of the present invention and does not limit the scope of the present invention. It should be noted that other equivalent modifications can be made by those skilled in the art in light of the teachings of the present invention, and all such modifications can be made as are within the scope of the present invention.