CN108642331B - 6181 aluminum alloy for automobile plate and preparation method thereof - Google Patents

Abstract

The invention provides a preparation method of 6181 aluminum alloy for automobile plates, which comprises the following components in percentage by weight: si: 0.7% -1%, Fe: less than or equal to 0.01 percent, Cu: less than or equal to 0.1 percent, Mn: 0.1% -0.18%, Mg: 0.7% -0.9%, Sr: 0.02-0.04%, the content of other impurities is not more than 0.02%, the total content is not more than 0.1%, and the balance is Al. The 6181 aluminum alloy for the automobile plate is obtained by smelting and continuously casting and rolling component raw materials to prepare a blank, homogenizing, carrying out primary cold rolling to intermediate annealing thickness, carrying out intermediate annealing, carrying out secondary cold rolling and carrying out aging treatment. The component proportion and the process method of the invention adjust the components through micro-alloying, greatly improve the mechanical property and the forming property of the alloy through the optimization of the processes of solid solution, artificial aging, composite pretreatment and the like, and completely meet the use requirements of the automobile sheet.

Description

6181 aluminum alloy for automobile plate and preparation method thereof

Technical Field

The invention belongs to the technical field of aluminum alloy for automobile plates and preparation thereof, and particularly relates to 6181 aluminum alloy for automobile plates and a preparation method thereof.

Background

Currently, aluminum sheet belts for automobile bodies mainly include three major aluminum alloys of 2000 series (Al-Cu-Mg series), 5000 series (Al-Mg series), and 6000 series (Al-Mg-Si series).

The 2000 series (Al-Cu series) aluminium alloy is a heat-treatable strengthened aluminium alloy, and has good welding performance and high strength and hardness. CuMgAl can be separated out in the aging process₂And CuAl₂And the strengthening phase is equal, so that the strength of the alloy is improved. However, the Cu element content in the series alloy is high, the corrosion resistance of the series alloy is poor compared with that of the aluminum alloy of the automobile body plate of other alloy series, the series alloy is easy to generate the phenomena of pitting corrosion, peeling corrosion, corrosion cracking and the like, and the age hardening capability in the baking varnish hardening process is weak, so that the industrial application of the 2000 series aluminum alloy automobile body plate is limited by the factors. For example, the main strengthening phase of AA2008 is CuMgAl₂The alloy has the advantages of difficult nucleation of age-precipitated phases and low age hardening capacity, and is mainly applied to inner plates.

The 5000 series (Al-Mg series) aluminum alloy is mainly characterized in that the alloy strength is improved through the combined action of solid solution strengthening and fine grain strengthening of Mg atoms in an aluminum matrix, and belongs to heat treatment non-strengthening aluminum alloy. The 5000 series aluminum alloy has excellent forming performance, corrosion resistance and welding performance, but the 5000 series aluminum alloy in an annealed state can generate a Luders strip and delayed yield in a processing deformation process, the surface of the plate is easy to wrinkle, the surface quality of the plate is influenced, the 5000 series aluminum alloy cannot be completely eliminated even after paint baking, and the surface quality requirement of an automobile body outer plate cannot be met. And the strength of the composite material is lower than that of 2000 series and 6000 series, and the composite material can also generate a softening phenomenon in the paint baking process and is mainly used for automobile body inner plates with less strict requirements on surface quality and complex shapes. Currently, HVNV5182-O material developed by HANV Metal, X5082-O and 5182-O materials developed by ALCOA, USA, have been used for automotive body inner panels.

The 6000 series (Al-Mg-Si series) aluminum alloy is a heat-treatment strengthenable aluminum alloy. The alloy has the excellent characteristics of high strength, good plasticity and corrosion resistance, easy coloring, convenient recycling and the like. The main alloy elements are Mg and Si elements, and an equal precipitation strengthening phase is formed in the paint baking process. The strength of the material is obviously improved. Compared with 2000 series and 5000 series aluminum alloys, 6000 series aluminum alloy automobile plates have the greatest advantage that the series aluminum alloys have relatively good plasticity and stamping forming performance. The product obtains higher strength through aging strengthening in the final baking finish treatment process, thereby meeting the requirement of dent resistance of the automobile body plate. Therefore, 6000 series aluminum alloys are widely used for automobile body inner and outer skin sheets. The existing problems are that the T4 and T4P states are basically in a theoretical state, and the strength improvement of the product after baking finish is greatly reduced in a natural aging state. Meanwhile, the series of alloys have large integral grain structures, so that the comprehensive performance is poor.

6181 aluminum alloy plate can be used as the outer plate of the automobile body and becomes the first choice material for lightening the automobile. However, the conventional production method mainly adopts a semi-continuous casting-hot rolling method to produce the blank, the whole process is very long, a series of processes such as casting, cooling, face milling, soaking, rolling, head and tail cutting and the like are required, and due to the existence of the processes, the cost is very high and the energy consumption is very high. Due to discontinuous block-by-block production, the head and the tail need to be cut off in the subsequent production process, the overall yield is low, and the yield is only 70% under the conventional condition.

The continuous casting and rolling technology is a technology for continuously producing blanks, is mature and applied to 3-series (Al-Mn) aluminum alloy at present, and is widely applied to production of curtain wall plates, air-conditioning aluminum foils and fin aluminum foils. However, because the solidification zone is short, the casting and rolling difficulty is greatly increased in the process of producing high-Mg, high-Si and other alloy materials, and the defects of high difficulty of the vertical plate, plate adhesion, edge cracking, irregular patterns on the surface and the like are easily caused, so that the use of the continuous casting and rolling technology on high-difficulty alloys is limited.

The important reason why the application of the continuous casting and rolling technology to the 6181 alloy is difficult to develop is the characteristic segregation phenomenon: the phenomenon of uneven distribution of the constituent elements in the alloy during crystallization is called segregation. Mainly divided into two types of segregation, i.e., segregation in the crystal and segregation in the macro phase, which is called as segregation in the dendrites. The method is characterized in that chemical compositions in a crystal grain range and in a crystal boundary are inconsistent, components with high melting points are often distributed in the crystal, and components with low melting points are often distributed in the crystal boundary. Macrosegregation mainly refers to the difference in composition between grains. This phenomenon is an inherent defect of the casting process, but since the continuous casting is formed by casting and rolling, the cooling rate is very fast, resulting in a large supercooling degree and thus a particularly large degree of segregation. The phenomenon that the segregation causes easy cracking in the rolling process and the performance of the finished product is not uniform is a serious process defect, which is one of the important reasons influencing the wide popularization of the technology in the aspect of the application of high-quality aluminum plate strips.

Disclosure of Invention

The invention aims to provide a 6181 aluminum alloy for automobile plates and a preparation method thereof.

Aiming at the application of automobile plates, a continuous casting and rolling process is selected, the defects of the existing alloy material in the aspect of continuous casting and rolling are overcome by adjusting the casting and rolling process, meanwhile, the segregation phenomenon is greatly reduced by adopting an electromagnetic intervention mode in the casting and rolling process, the defects of the existing alloy material are overcome by adjusting components through microalloying on the basis of 6181 alloy and optimizing the processes of solid solution, artificial aging, pretreatment and the like, the aluminum alloy (6181A brand aluminum alloy plate) required by the authority of the patent is designed and developed, the technical weakness of the existing alloy is overcome, and patent application is carried out. The alloy plate has higher yield strength than 6016 aluminum alloy plates, and simultaneously has better forming performance. The alloy is an excellent automobile outer plate material, and the composition of the alloy is approximately the same as that of an outer plate element, so that the alloy can effectively improve the recycling performance, and can be used as a body inner plate instead of 5182 and 5754.

The technical purpose of the invention is realized by the following technical scheme:

a preparation method of 6181 aluminum alloy for automobile plates comprises the following raw materials in percentage by weight:

si: 0.7% -1%, Fe: less than or equal to 0.01 percent, Cu: less than or equal to 0.1 percent, Mn: 0.1-0.18%, Mg: 0.7-0.9%, Sr: 0.02-0.04%, the total amount of other impurities is not more than 0.1%, and the balance of Al;

the preparation method comprises the following steps:

s1, smelting and continuously casting and rolling component raw materials to obtain a blank, wherein the casting and rolling speed is 0.70-0.80 m/min, the casting temperature is 685-695 ℃, and electromagnetic field intervention is used during casting and rolling; the pulse current frequency is 18-20%, the duty ratio is 20-23%, and the static magnetic field magnetic induction intensity is 21-24 mT;

s2, homogenizing, namely performing two-stage soaking treatment by adopting a two-stage soaking process, wherein the treatment is performed in the following steps of (440-480) DEG C x (3-10) h → (520-550) DEG C x (14-20) h → air cooling;

s3, cold rolling to intermediate annealing thickness;

s4, intermediate annealing: controlling the metal heat preservation temperature to be 310-360 ℃, and preserving the heat of the metal for 2-4 hours;

s5, rolling the finished product, performing solid solution at 540-560 ℃ for 35-45 min, and then performing water quenching, wherein the water temperature is 20-25 ℃;

s6, pre-aging treatment: performing pre-stretching treatment of 1.5-2.5%, and then immediately performing pre-aging treatment at 120-160 ℃ for 5-15 min;

s7, aging treatment: stored at 25 ℃ for 14 days.

Preferably, the thickness of the blank in the step S1 is 6.0-8.0 mm.

Preferably, the steel is rolled to a thickness of 1.0-1.2 mm in step S5, and the thickness tolerance is controlled to +/-1%.

Preferably, in the step S3, the single-pass machining rate is controlled to be 35-45%, and the thickness tolerance of the finished product is +/-1%.

Preferably, in step S3, the steel sheet is cold rolled to a thickness of 1.4 to 1.7 mm.

Preferably, the individual content of other impurities in the feedstock is no more than 0.02%.

One of the technical solutions of the invention is to optimize the mechanical properties and the punch forming properties of the alloy by microalloying (adding a proper amount of Mn and Sr elements), reduce the yield strength of the alloy in the T4P state by improving the optimized solid solution process and developing a pre-stretching and artificial aging composite pretreatment process, and improve the strength after baking, thereby developing the aluminum alloy for the automobile plate.

The addition of a proper amount of Mn element improves the alloy performance, after the Mn element is added, the Mn element partially replaces the Fe element to promote the needle-shaped β -Al-Fe-Si phase to be dissolved and broken and converted into a fine and dispersed granular α -Al (Mn, Fe) phase, so that on one hand, the recrystallization and grain growth process of the alloy in the solution treatment process can be effectively inhibited, and the effect of refining grains is achieved, on the other hand, nucleation points can be provided for the main strengthening precipitation phase of the alloy, the dispersion precipitation of the main strengthening phase is promoted, the forming performance and the mechanical property of the alloy are improved to a certain extent, and the forming performance of the alloy can be improved by adding 0.10-0.18% of Mn element into 6181A aluminum alloy through research.

After the Sr element is added, the Sr element is used as a surface active element and added into an aluminum matrix, firstly, microalloying effect can be generated, thermodynamic balance in the alloy is changed, segregation of alloy elements such as Si, Mn and the like in a grain boundary is reduced, and finally grains are refined, β -AlFeSi can be converted into α -AlFeSi, so that fine grain strengthening and dispersion strengthening are generated, and the alloy deformation is more uniform, so that the strength and the plasticity of the alloy are improved.

The double-roller thin strip casting and rolling process can reduce complex procedures such as heating, surface milling, repeated rolling and the like, greatly simplifies the traditional thin strip production process flow, shortens the production period, can effectively reduce the production cost of enterprises, saves natural resources and reduces pollutant discharge, and accords with the current economic development trend of low carbon and environmental protection.

The continuous and stable production can lead the production to achieve the effects of high efficiency and high yield. The head and tail cutting after hot rolling is well avoided, and the yield is improved by 15-20%.

Pioneering use of electromagnetic complex field to intervene solidification behavior: the composite field composed of the steady magnetic field and the pulse current with different intensities is added into the casting and rolling process, the composite field has a good effect of inhibiting slab center segregation, wherein the pulse current frequency is 18-20%, the duty ratio is 20-23%, and the static magnetic field magnetic induction intensity is in a range of 21-24 mT.

The casting and rolling process optimizes the production of the 6-series cast and rolled aluminum alloy with high alloy content: the 6-series cast-rolling aluminum alloy blanks meeting the requirements can be produced by reasonably controlling the casting-rolling speed (0.7-0.8 m/min) and the casting temperature (685-695 ℃).

Establishment of high-temperature solid solution process: the optimal solution treatment process for the aluminum alloy cold-rolled sheet with the temperature of 540-560 ℃ for 35-45 min is established. In the temperature range of 490-590 ℃, the soluble crystal phase in the alloy structure gradually decreases with the increase of the solid solution temperature, the recrystallization ratio and the grain size gradually increase, and the strength and the elongation of the alloy T6 state both tend to increase first and then decrease. When the solid solution temperature is 540-560 ℃, a higher value is reached.

The artificial aging and pre-stretching composite treatment process comprises the following steps: a composite pretreatment process is developed, wherein (1.5-2.5)% of pre-stretching is carried out, then (120-160) ° C (5-15) min of pre-aging treatment is carried out immediately, natural aging can be inhibited strongly, the baking hardening performance of the alloy is improved, and an alloy plate with better comprehensive performance is obtained, wherein the T4P-state yield strength of the 6181A aluminum alloy containing 0.15% of Mn elements is only 159MPa, and the T8X-state yield strength reaches 323MPa.

Compared with the prior art, the invention has the following advantages and effects:

the component proportion and the process method of the invention adjust the components through micro-alloying, greatly improve the mechanical property and the forming property of the alloy through the optimization of the processes of solid solution, artificial aging, composite pretreatment and the like, and completely meet the use requirements of the automobile sheet.

Detailed Description

The present invention is further illustrated by the following specific examples, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the present invention are commercially available.

Example 1

The raw materials comprise:

the preparation method comprises the following steps:

(1) and (3) blending the components of the alloy by using 99.7 percent of aluminum ingots, finely adjusting the components of the parts with insufficient components by using intermediate alloy, and smelting and continuously casting and rolling to obtain a blank with the thickness of 7.5 mm. The casting and rolling speed is 0.79m/min, and the casting temperature is 690 ℃. The casting and rolling area is intervened by using an electromagnetic field, and the specific parameters are as follows: the pulse current frequency is 19%, the duty ratio is 22%, and the static magnetic field magnetic induction intensity is 24 mT.

(2) In the soaking process, the blank adopts a two-stage soaking process, specifically 460 ℃ multiplied by 4h → 535 ℃ multiplied by 16h → air cooling.

(3) Cold rolling to 1.4mm thickness, 4 total pass number of cold rolling, and +/-1% thickness tolerance of finished products.

(4) Intermediate annealing: the metal heat preservation temperature is controlled at 350 ℃, and the metal heat preservation is carried out for 2 hours.

(5) Rolling the finished product to 1.0 thickness, and controlling the thickness tolerance to +/-1%.

(6) The solution quenching treatment process comprises the following steps: at 550 ℃ for 40min, and then water quenching is carried out, wherein the temperature is 20 ℃.

(7) The composite pretreatment process comprises the following steps: 2% pre-stretching was carried out, followed immediately by pre-aging at 150 ℃ for 10 min.

(8) The natural aging process comprises the following steps: storing for 14 days at normal temperature and 25 ℃.

Comparative examples 1 to 7:

first, comparative example 1 was made of 5182 grade aluminum alloy of international standard, and the process conditions beyond the present invention are indicated by "#". 6181 alloy comparative examples 2-7 are prepared according to conventional components and processes.

5182 aluminum alloy comparative example 1:

the chemical composition (WT%) of the material is as follows:

(1) the components are mixed according to the alloy components, and 99.7 percent of electrolytic aluminum ingot is adopted to be mixed with Mg ingot and other intermediate alloy. After smelting, refining, deslagging, stirring, analyzing and adjusting to be divided, the molten aluminum enters a standing furnace, standing, refining, degassing, deslagging, Al-5Ti-1B wires are added into the molten aluminum, and then the molten aluminum enters a casting machine to be cast into ingots. And milling the surface of the cast ingot.

(2) And soaking the ingot, wherein the heat preservation temperature of the ingot is 560 ℃, and the heat preservation time of the ingot is 7 hours. The initial rolling temperature of hot rolling is controlled at 510 ℃, the final rolling temperature is controlled at 270 ℃, the thickness of a hot rolling blank is 6.0mm, and the total number of hot rolling passes is 29.

(3) The hot rolled blank is rolled to the thickness of 1.0mm by cold rolling, the total number of cold rolling passes is 5, and the thickness tolerance of the finished product is +/-1%.

(4) The annealing temperature of the finished product is 310 ℃, and the heat preservation time is 4 hours.

(5) In the process of stretch bending, straightening and rewinding, the elongation is controlled to be 0.03 percent, and the unit tension is 8 Mpa.

Comparative example 2:

(1) and (3) blending the components of the alloy by using 99.7 percent of aluminum ingots, finely adjusting the components of the parts with insufficient components by using intermediate alloy, and smelting and continuously casting and rolling to obtain a blank with the thickness of 7.5 mm. The casting and rolling speed is 0.79m/min, and the casting temperature is 690 ℃. The casting and rolling zones were not interfered with electromagnetic fields (#).

(2) In the soaking process, the blank adopts a two-stage soaking process, specifically 460 ℃ multiplied by 4h → 535 ℃ multiplied by 16h → air cooling.

(3) Cold rolling to 1.4mm thickness, 4 total pass number of cold rolling, and +/-1% thickness tolerance of finished products.

(4) Intermediate annealing: the metal heat preservation temperature is controlled at 350 ℃, and the metal heat preservation is carried out for 2 hours.

(5) Rolling the finished product to 1.0 thickness, and controlling the thickness tolerance to +/-1%.

(6) The solution quenching treatment process comprises the following steps: 550 ℃ for 40 min. Then water quenching is carried out, and the water temperature is 20 ℃.

(7) The composite pretreatment process comprises the following steps: 2% pre-stretching was carried out, followed immediately by pre-aging at 150 ℃ for 10 min.

(8) The natural aging process comprises the following steps: storing for 14 days at normal temperature and 25 ℃.

Comparative example 3:

(1) according to the alloy components, 99.7% of aluminum ingots are used for blending, Mn and Sr elements (#) are not added, the part with insufficient components is finely adjusted by using intermediate alloy, and a blank is prepared by smelting and continuous casting rolling, wherein the thickness of the blank is 7.5 mm. The casting and rolling speed is 0.75m/min, and the casting temperature is 687 ℃. The casting and rolling area is intervened by using an electromagnetic field, and the specific parameters are that the frequency of a pulse current is 18%, the duty ratio is 20%, and the magnetic induction intensity of the static magnetic field is 22 mT.

(2) In the soaking process, the blank adopts a two-stage soaking process, specifically 460 ℃ multiplied by 4h → 535 ℃ multiplied by 16h → air cooling.

(3) Cold rolling to 1.4mm thickness, 4 total pass number of cold rolling, and +/-1% thickness tolerance of finished products.

(4) Intermediate annealing: the metal heat preservation temperature is controlled at 340 ℃, and the metal heat preservation is carried out for 3 hours.

(5) Rolling the finished product to 1.0 thickness, and controlling the thickness tolerance to +/-1%.

(6) The solution treatment process comprises the following steps: 550 ℃ for 40 min. The solution quenching treatment process comprises the following steps: 550 ℃ for 40 min. Then water quenching is carried out, and the water temperature is 20 ℃.

(7) The composite pretreatment process comprises the following steps: 2% pre-stretching is carried out, and then pre-aging treatment at 150 ℃ for 6min is immediately carried out.

(8) The natural aging process comprises the following steps: storing for 14 days at normal temperature and 25 ℃.

Comparative example 4:

(1) according to the alloy components, 99.7% of aluminum ingots are used for blending to obtain the components in the table, the parts with insufficient components are finely adjusted by using intermediate alloys, and the blanks are prepared by smelting and continuous casting and rolling, wherein the thickness of the blanks is 7.0 mm. The casting and rolling speed is 0.76m/min, and the casting temperature is 687 ℃. The casting and rolling area is intervened by using an electromagnetic field, and the specific parameters are that the frequency of a pulse current is 19%, the duty ratio is 20%, and the magnetic induction intensity of the static magnetic field is 23 mT.

(2) In the soaking process, the blank adopts a two-stage soaking process, specifically 460 ℃ multiplied by 4h → 535 ℃ multiplied by 16h → air cooling.

(3) Cold rolling to 1.45mm thickness, 4 total pass number of cold rolling, and +/-1% thickness tolerance of finished products.

(4) Intermediate annealing: the metal heat preservation temperature is controlled at 330 ℃, and the metal heat preservation is carried out for 4 hours.

(5) Rolling the finished product to 1.0 thickness, and controlling the thickness tolerance to +/-1%.

(6) The solution quenching treatment process comprises the following steps: 590 ℃ C. (#) x 40min, then water quenching is carried out, and the water temperature is 20 ℃.

(7) The composite pretreatment process comprises the following steps: 2.2% pre-stretching was performed immediately followed by pre-aging at 125 ℃ for 6 min.

(8) The natural aging process comprises the following steps: storing for 14 days at normal temperature and 25 ℃.

Comparative example 5:

(1) according to the alloy components, 99.7% of aluminum ingots are used for blending to obtain the components in the table, the parts with insufficient components are finely adjusted by using intermediate alloys, and the blanks are prepared by smelting and continuous casting and rolling, and the thickness of the blanks is 6 mm. The casting and rolling speed is 0.79m/min, and the casting temperature is 689 ℃. The casting and rolling area is intervened by using an electromagnetic field, and the specific parameters are as follows: the pulse current frequency is 19%, the duty ratio is 22%, and the static magnetic field magnetic induction intensity is 23 mT.

(2) In the soaking process, the blank adopts a two-stage soaking process, specifically 460 ℃ multiplied by 4h → 535 ℃ multiplied by 16h → air cooling.

(3) Cold rolling to 1.6mm thickness, 3 total pass number of cold rolling, and +/-1% thickness tolerance of finished products.

(4) Intermediate annealing: the metal heat preservation temperature is controlled at 350 ℃, and the metal heat preservation is carried out for 2 hours.

(5) Rolling the finished product to 1.0 thickness, and controlling the thickness tolerance to +/-1%.

(6) The solution quenching treatment process comprises the following steps: 550 ℃ for 40 min. Then water quenching is carried out, and the water temperature is 20 ℃.

(7) The composite pretreatment process comprises the following steps: the pre-stretching and pre-aging process (#) was not performed.

(8) The natural aging process comprises the following steps: storing for 14 days at normal temperature and 25 ℃.

Comparative example 6:

(1) according to the alloy components, 99.7% of aluminum ingots are used for blending to obtain the components in the table, the parts with insufficient components are finely adjusted by using intermediate alloys, and the blanks are prepared by smelting and continuous casting and rolling, and the thickness of the blanks is 6 mm. The casting and rolling speed is 0.76m/min, and the casting temperature is 688 ℃. The casting and rolling area is intervened by using an electromagnetic field, and the specific parameters are as follows: the pulse current frequency is 19%, the duty ratio is 23%, and the static magnetic field magnetic induction intensity is 24 mT.

(2) In the soaking process, the blank adopts a two-stage soaking process, specifically 460 ℃ multiplied by 4h → 535 ℃ multiplied by 16h → air cooling.

(3) Cold rolling to 1.6mm thickness, 3 total pass number of cold rolling, and +/-1% thickness tolerance of finished products.

(4) Intermediate annealing: the metal heat preservation temperature is controlled at 350 ℃, and the metal heat preservation is carried out for 2 hours.

(5) Rolling the finished product to 1.0 thickness, and controlling the thickness tolerance to +/-1%.

(6) The solution quenching treatment process comprises the following steps: 550 ℃ for 40 min. Then water quenching is carried out, and the water temperature is 20 ℃.

(7) The composite pretreatment process comprises the following steps: pre-stretching was not performed, only pre-aging (#) at 150 ℃ for 6min was performed.

(8) The natural aging process comprises the following steps: storing for 14 days at normal temperature and 25 ℃.

Comparative example 7:

(1) according to the alloy components, 99.7% of aluminum ingots are used for blending to obtain the components in the table, the parts with insufficient components are finely adjusted by using intermediate alloys, and the blanks are prepared by smelting and continuous casting and rolling, and the thickness of the blanks is 6 mm. The casting and rolling speed is 0.77m/min, and the casting temperature is 690 ℃. The casting and rolling area is intervened by using an electromagnetic field, and the specific parameters are as follows: the pulse current frequency is 20%, the duty ratio is 21%, and the static magnetic field magnetic induction intensity is 23 mT.

(2) In the soaking process, the blank adopts a two-stage soaking process, specifically 460 ℃ multiplied by 4h → 535 ℃ multiplied by 16h → air cooling.

(3) Cold rolling to 1.6mm thickness, 3 total pass number of cold rolling, and +/-1% thickness tolerance of finished products.

(4) Intermediate annealing: the metal heat preservation temperature is controlled at 350 ℃, and the metal heat preservation is carried out for 2 hours.

(5) Rolling the finished product to 1.0 thickness, and controlling the thickness tolerance to +/-1%.

(6) The solution quenching treatment process comprises the following steps: 550 ℃ for 40 min. Then water quenching is carried out, and the water temperature is 20 ℃.

(7) The composite pretreatment process comprises the following steps: no pre-ageing treatment was carried out, only 2% pre-stretching (#) was carried out.

(8) The natural aging process comprises the following steps: storing for 14 days at normal temperature and 25 ℃.

The comparative and example waste usage ratios are compared to the finished product parameters as follows:

Claims (8)

1. the preparation method of the 6181 aluminum alloy for the automobile plate is characterized in that the raw materials comprise the following components in percentage by weight:

si: 0.7% -1%, Fe: less than or equal to 0.01 percent, Cu: less than or equal to 0.1 percent, Mn: 0.1-0.18%, Mg: 0.7-0.9%, Sr: 0.02-0.04%, the total amount of other impurities is not more than 0.1%, and the balance of Al; the preparation method comprises the following steps:

s1, smelting and continuously casting and rolling component raw materials to obtain a blank, wherein the casting and rolling speed is 0.70-0.80 m/min, the casting temperature is 685-695 ℃, and electromagnetic field intervention is used during casting and rolling; the pulse current frequency is 18-20%, the duty ratio is 20-23%, and the static magnetic field magnetic induction intensity is 21-24 mT;

s2, homogenizing, namely performing two-stage soaking treatment by adopting a two-stage soaking process, wherein the treatment is performed in the following steps of (440-480) DEG C x (3-10) h → (520-550) DEG C x (14-20) h → air cooling;

s3, cold rolling to intermediate annealing thickness;

s4, intermediate annealing: controlling the metal heat preservation temperature to be 310-360 ℃, and preserving the heat of the metal for 2-4 hours;

s5, rolling the finished product, performing solid solution at 540-560 ℃ for 35-45 min, and then performing water quenching, wherein the water temperature is 20-25 ℃;

s6, pre-aging treatment: performing pre-stretching treatment of 1.5-2.5%, and then immediately performing pre-aging treatment at 120-160 ℃ for 5-15 min;

s7, aging treatment: stored at 25 ℃ for 14 days.

2. The method as claimed in claim 1, wherein the thickness of the billet in step S1 is 6.0 to 8.0 mm.

3. The method for preparing the alloy steel plate according to claim 1, wherein the alloy steel plate is rolled to a thickness of 1.0-1.2 mm in the step S5, and the thickness tolerance is controlled to be +/-1%.

4. The manufacturing method according to claim 1, wherein the single-pass reduction rate in step S3 is controlled to be 35-45%, the total number of cold rolling passes is 4, and the thickness tolerance of the finished product is ± 1%.

5. The method of claim 1, wherein in step S3, the cold rolling is performed to a thickness of 1.4 to 1.7 mm.

6. The method of claim 1, wherein the individual content of other impurities in the feedstock is no greater than 0.02%.

7. A6181 aluminium alloy prepared by the process of any of claims 1 to 6.

8. A6181 aluminium alloy according to claim 7, wherein the 6181 aluminium alloy is used as vehicle body inner or outer panel.