CN114540649A - High-forming baking-resistant 5xxx series aluminum alloy plate and preparation method thereof - Google Patents

Abstract

The invention provides a high-forming baking-resistant 5xxx series aluminum alloy plate and a preparation method thereof. The method comprises the steps of sequentially carrying out ingot casting, two-stage homogenization treatment, hot rolling, intermediate annealing, cold rolling and final annealing on aluminum alloy raw materials with different Mn contents, wherein the mass percentages of Mg5.0-7.5 wt.%, Cu0.15-0.6 wt.%, Si is less than or equal to 0.1 wt.%, Fe0.1-0.4 wt.%, Mn0.05-0.15 wt.%, Cr is less than or equal to 0.05 wt.%, Ti is less than or equal to 0.1 wt.%, the total mass percentage of inevitable impurities is less than or equal to 0.15 wt.%, and the balance Al, and carrying out different homogenization processes on the aluminum alloy raw materials with different Mn contents to obtain the high-forming baking-resistant 5xxx series aluminum alloy plate. According to the invention, through the adjustment of the aluminum alloy components and the matching of the preparation process, the plate has good forming performance, baking resistance and mechanical property, YPE is 0, and the comprehensive performance is obviously superior to that of the existing 5-series high-strength aluminum alloy material.

Description

High-forming baking-resistant 5xxx series aluminum alloy plate and preparation method thereof

Technical Field

The invention relates to the field of nonferrous metals, in particular to a high-forming baking-resistant 5xxx series aluminum alloy plate and a preparation method thereof.

Background

With the continuous progress of light weight in the automobile field, aluminum alloy has a series of excellent characteristics such as high specific strength, good corrosion resistance, good processability, extremely high recyclability and the like, and becomes an optimal material for light weight of transportation. The 5xxx series aluminum alloy has good forming performance and higher strength, can be used for manufacturing parts with complex shapes, and has great development potential in application to automobiles. Compared with the traditional steel, the difficulty of popularization and application of the existing aluminum alloy automobile plate is that the cost of parts is far higher than that of the traditional steel, the formability is not as good as that of a steel plate, and the automobile parts with complex structures are difficult to prepare. At present, 5182 and 5754 alloys are mainly used for automobile body structural parts, the elongation of the alloys is generally lower than 28%, the forming requirements of complex structural parts are difficult to meet, and the strength of the finished products is reduced after baking finish, so that the application of 5xxx series alloys is limited.

At present, researchers in patents CN103255323 and CN104862551 have added Cu and Zn elements to improve the strength of Al-Mg series alloy after baking finish, but the former after straightening is subjected to stress relief annealing at 240-300 ℃ to cause solid-dissolved Cu and Zn atoms to be rapidly precipitated to form coarse second phases, which results in greatly reduced strengthening effect; the content of Cu and Zn elements is further improved, the elongation is low, the pre-aging time of 60-100 ℃/6-8 h is increased, the cost is increased, the application of the alloy in the automobile industry is limited, the high-temperature brittleness of the alloy is increased by adding more Cu and Zn elements in the high-Mg alloy, the processing cost is further increased, and the practical application is greatly limited. In patents CN111593236 and CN103911531, a small amount of Cu element is also added, but bake hardening performance is not examined, and the latter has a lower elongation due to a higher Mn content.

In addition, patent CN103320729B discloses a composition and processing technology of 5182 type aluminum alloy, which realizes the purpose of improving ludwiss strip by optimizing the composition and processing technology, but the material does not contain Cu and has low Mg content, so that the material has low strength and cannot be subjected to baking finish treatment, thereby affecting further high-end application of the material. Patent US5441582 provides a bake hardenable 5 series aluminium alloy with a Cu content of 0.3-1.0 wt.%, which gives the material a certain bake hardening effect and reduces the adverse effects on natural ageing. However, because the Mg content in the material is low (1.5-3.5 wt.%), the overall strength of the material after baking is low (the yield strength is lower than 150 MPa). Patent US5460666 provides an Al-Mg-Si-Cu alloy with a Mg content of 1.5-3.5 wt.% and a Cu content of 0.3-1.0 wt.%, and similar to the alloy of US5441582, the yield strength after bake hardening of the material is also substantially lower than 150 MPa.

From the search of the related inventions at home and abroad, the alloy has unreasonable components and process design, so that the mechanical property of the alloy is insufficient or the baking and hardening effects are not good; or the point of attention is that the Luders strip of the 5xxx series aluminum alloy material is eliminated, the guarantee of the material baking hardening performance is neglected, and the deficiency of the material strength performance is caused.

Disclosure of Invention

The invention mainly aims to provide a high-forming baking-resistant 5xxx series aluminum alloy plate and a preparation method thereof, and aims to solve the problem that the 5xxx series aluminum alloy plate in the prior art is difficult to have forming performance, baking resistance and mechanical property at the same time.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for producing a high-formability baking-resistant 5 xxx-series aluminum alloy sheet, comprising the steps of: step S1, mixing raw materials of the 5xxx series aluminum alloy and melting and casting ingots to obtain aluminum alloy cast ingots; wherein the aluminum alloy comprises the following components in percentage by weight: 5.0-7.5 wt.% of Mg, 0.15-0.6 wt.% of Cu, less than or equal to 0.1 wt.% of Si, 0.1-0.4 wt.% of Fe, 0.05-0.15 wt.% of Mn, less than or equal to 0.05 wt.% of Cr, less than or equal to 0.1 wt.% of Ti, less than or equal to 0.15 wt.% of the total of inevitable impurities, and the balance of Al; step S2, performing two-stage homogenization treatment on the aluminum alloy cast ingot, wherein in the two-stage homogenization treatment, the temperature is increased to 420-445 ℃ at the speed of 25-60 ℃/h, the temperature is kept for 2-4 h, the first homogenization treatment is performed, then the temperature is increased to 500-540 ℃ at the speed of 20-30 ℃/h, the temperature is kept for 4-10 h, and the second homogenization treatment is performed; step S3, carrying out hot rolling on the homogenized cast ingot to obtain a hot rolled plate; step S4, performing intermediate annealing, cold rolling, final annealing and cooling on the hot rolled plate to obtain a high-forming baking-resistant 5xxx series aluminum alloy; in the second homogenization treatment, when the weight percentage of Mn in the aluminum alloy is more than or equal to 0.05 wt.% and less than 0.1 wt.%, heating to 500-530 ℃ at the speed of 20-30 ℃/h, and preserving heat for 4-10 h; when the weight percentage of Mn in the aluminum alloy is more than or equal to 0.1 wt.% and less than 0.15 wt.%, heating to 520-540 ℃ at the speed of 20-30 ℃/h, and preserving heat for 6-10 h.

Further, the aluminum alloy comprises the following components in percentage by weight: 5.5-7.5 wt.% of Mg, 0.5-0.6 wt.% of Cu, less than or equal to 0.1 wt.% of Si, 0.1-0.4 wt.% of Fe, 0.05-0.15 wt.% of Mn, less than or equal to 0.05 wt.% of Cr, less than or equal to 0.1 wt.% of Ti, less than or equal to 0.15 wt.% of the total inevitable impurities, and the balance of Al.

Further, the weight percentage of Mg/Mn in the aluminum alloy is (50-120): 1, and the weight percentage of Cu/Mn in the aluminum alloy is (1-6): 1.

Further, in the first homogenization treatment, the temperature is raised to 430-440 ℃ at the rate of 30-60 ℃/h, and the temperature is kept for 3-4 h.

Further, in the second homogenization treatment, when the weight percentage of Mn in the aluminum alloy is 0.05-0.08 wt.%, heating to 500-510 ℃ at the speed of 20-30 ℃/h, and preserving heat for 4-10 h; when the weight percentage of Mn in the aluminum alloy is 0.1-0.15 wt.%, the temperature is raised to 520-530 ℃ at the rate of 20-30 ℃/h, and the temperature is preserved for 6-10 h.

Furthermore, the initial rolling temperature in the hot rolling process is 460-520 ℃, the final rolling temperature is more than or equal to 300 ℃, the deformation rate of the cast ingot is 1-3%, and the total deformation is more than or equal to 95%.

Further, the temperature of the intermediate annealing process is 280-380 ℃; in the cold rolling process, the cold rolling reduction rate is 30-60%.

Further, continuous annealing is adopted in the final annealing process, the continuous annealing temperature is 500-550 ℃, and the time is 20-40 s; preferably, the temperature of the continuous annealing is 520-550 ℃.

According to another aspect of the invention, a high-forming baking-resistant 5xxx series aluminum alloy plate is also provided, and is prepared by the preparation method; preferably, the yield strength of the high-forming baking-resistant 5xxx series aluminum alloy plate is 110-140 MPa, the elongation is more than or equal to 30%, the strain hardening index is more than or equal to 0.34, the average plastic strain ratio is more than or equal to 0.70, YPE is 0, and the stable standing time is more than or equal to 180 days.

Furthermore, after the high-forming baking-resistant 5xxx series aluminum alloy plate is subjected to simulated baking finish treatment at 180 ℃/20min, the tensile strength is more than or equal to 300MPa, and the yield strength is improved by more than or equal to 45MPa compared with that before baking.

Compared with the prior art, the invention realizes the following beneficial effects:

1. according to the invention, the contents of Mg and Cu are adjusted, so that the material has remarkable baking and hardening capacity, and the phenomenon that the existing high-strength 5-series aluminum alloy is easy to soften or insufficient in improvement of mechanical properties in the baking process is avoided; meanwhile, the content of the transition group elements is optimized, so that the grain size of the material is controlled, and the formation of coarse grains is avoided. In addition, the presence of the dispersed phase of the transition group element increases the work hardening capacity of the material, hindering the formation of deformed bands.

2. By adopting a multistage homogenization process, particularly a corresponding homogenization process aiming at aluminum alloy materials with different Mn contents, the invention can further accurately regulate and control the size and distribution of Mn-containing particles on the basis of full solid solution of beta phase, and ensure that solute elements are fully diffused and crystal grains are not abnormally grown. The grain size is controlled to be 30-70 mu m through an intermediate annealing and a final annealing system, and YPE can be reduced to 0, so that the material has good forming performance and a surface with high forming quality.

In conclusion, the Mg and Cu contents of the invention exceed the component system of the existing 5023 aluminum alloy, and the Mg content exceeds the highest Mg content of the existing commercial deformation 5 aluminum alloy, but the innovative process of the invention promotes the tissue optimization, so the material of the invention does not have the phenomenon of Lvdes strip common in the conventional high-Mg aluminum alloy material, and simultaneously, the corresponding homogenization process is adopted aiming at the aluminum alloy materials with different Mn contents, so the plate of the invention has good forming performance before baking, the yield strength is 110-140 MPa, the elongation is more than or equal to 30%, the strain hardening index is more than or equal to 0.34, the average plastic strain ratio is more than or equal to 0.70, the YPE is 0, the standing stability is good, the alloy tensile strength after the baking of the material is more than or equal to 300MPa, the yield strength is improved more than or equal to 45MPa, the baking hardening capacity is obvious, and the comprehensive performance of the invention is obviously better than that of the existing 5 high-strength aluminum alloy material, the surface quality is good, can be used as the outer panel of the automobile body.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic representation of tensile strain versus tensile stress according to example 1 of the present invention; and

FIG. 2 shows a schematic of tensile strain versus tensile stress for comparative example 1; and

FIG. 3 is a schematic diagram showing the change of elongation after 180 days of parking according to embodiment 1 of the present invention; and

FIG. 4 is a schematic view showing intensity variation during 180-day parking according to embodiment 1 of the present invention; and

FIG. 5 shows a graph of grains after a second homogenization treatment corresponding to 0.05 wt.% Mn in accordance with example 1 of the present invention; and

FIG. 6 shows a graph of grains after a second homogenization treatment corresponding to 0.1 wt.% Mn in accordance with example 3 of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

Interpretation of terms:

the weight percentage is as follows: the mass (weight) of a certain alloy component accounts for the percentage of the total mass.

Tensile strength: the maximum resistance of the aluminum alloy to damage under the action of tensile force, with the symbol R_m。

Yield strength: the yield limit at which the aluminum alloy yields is specified as the stress value at which 0.2% residual deformation occurs. Obtaining a stress-strain curve through a uniaxial tensile test, and obtaining yield strength data through the curve, wherein the symbol is R_p0.2。

Initial state yield strength: casting, homogenizing, hot rolling, intermediate annealing, cold rolling and final annealing to obtain the finished plate. And standing the finished plate at room temperature for 7 days, and testing the mechanical property through a unidirectional tensile test to obtain the yield strength.

Yield strength after baking: and standing the finished plate at room temperature for 7 days, performing 180 ℃/20min simulation paint baking on the finished plate, and testing the yield strength in a baking state through a unidirectional tensile test.

YPE: yield Point Elongation, refers to the difference in Elongation of a material at the beginning and end of discontinuous Yield.

Elongation percentage: the percentage of the ratio of the total deformation after the tensile fracture of the aluminum alloy to the original length is marked as A%.

Strain hardening index: the aluminum alloy material has the ability of resisting uniform plastic deformation, and the symbol is n.

Average plastic strain ratio: the aluminum alloy resists thinning or thickening when subjected to tensile or compressive forces, designated r.

As described in the background of the invention, the problem that 5xxx series aluminum alloys have difficulty in simultaneously achieving formability, baking resistance and mechanical properties exists in the prior art. In order to solve the above problems, in an exemplary embodiment of the present invention, there is provided a method of manufacturing a high-formability baking-resistant 5 xxx-series aluminum alloy sheet, including the steps of: step S1, mixing raw materials of the 5xxx series aluminum alloy and melting and casting ingots to obtain aluminum alloy cast ingots; wherein the aluminum alloy comprises the following components in percentage by weight: 5.0-7.5 wt.% of Mg, 0.15-0.6 wt.% of Cu, less than or equal to 0.1 wt.% of Si, 0.1-0.4 wt.% of Fe, 0.05-0.15 wt.% of Mn, less than or equal to 0.05 wt.% of Cr, less than or equal to 0.1 wt.% of Ti, less than or equal to 0.15 wt.% of the total of inevitable impurities, and the balance of Al; step S2, performing two-stage homogenization treatment on the aluminum alloy cast ingot, wherein in the two-stage homogenization treatment, the temperature is increased to 420-445 ℃ at a speed of 25-60 ℃/h, the temperature is kept for 2-4 h, the first homogenization treatment is performed, then the temperature is increased to 500-540 ℃ at a speed of 20-30 ℃/h, the temperature is kept for 4-10 h, and the second homogenization treatment is performed; step S3, carrying out hot rolling on the homogenized cast ingot to obtain a hot rolled plate; step S4, performing intermediate annealing, cold rolling, final annealing and cooling on the hot rolled plate to obtain a high-forming baking-resistant 5xxx series aluminum alloy; in the second homogenization treatment, when the weight percentage of Mn in the aluminum alloy is more than or equal to 0.05 wt.% and less than 0.1 wt.%, heating to 500-530 ℃ at the speed of 20-30 ℃/h, and preserving heat for 4-10 h; when the weight percentage of Mn in the aluminum alloy is more than or equal to 0.1 wt.% and less than 0.15 wt.%, heating to 520-540 ℃ at the speed of 20-30 ℃/h, and preserving heat for 6-10 h.

Mg is a main strengthening element of the 5xxx aluminum alloy, and improves the yield strength of the alloy plate mainly by a solid solution strengthening method. With Mg content below 5.0 wt.%, the strength of the alloy is low; however, when the Mg content exceeds 7.5 wt.%, the castability is seriously deteriorated. Therefore, the Mg content is controlled to be 5.0-7.5 wt.%. Cu has the effects of solid solution strengthening and time effectiveness, and a small amount of Cu element is added into the 5xxx series alloy, so that the alloy is not softened after being subjected to paint baking treatment, but the Cu element can seriously reduce the hot working performance of the high Mg alloy and increase the high-temperature crack tendency during welding, and therefore, the Cu content is controlled to be 0.15-0.5 wt.%. The Mg and Cu contents of the invention exceed the component system of the existing 5023 aluminum alloy, the Mg content exceeds the highest Mg content of the existing commercial wrought 5 aluminum alloy, but the innovative process of the invention promotes the tissue optimization, so the material of the invention does not have the phenomenon of the Luders strip common in the conventional high-Mg aluminum alloy material.

Mn mainly plays a role in inhibiting recrystallization in the alloy, can improve the strength of the material and the corrosion resistance, but the plasticity of the alloy can be obviously reduced due to the excessively high content of Mn, so that the content of Mn is not higher than 0.2 wt.%, and in order to further improve the strength performance of the material, the content of Mn is controlled to be 0.05-0.15 wt.%, and meanwhile, a multistage homogenization process is adopted, and a corresponding second homogenization process is adopted particularly for aluminum alloy materials with different Mn contents, so that the size and distribution of Mn-containing particles can be regulated, the full diffusion of solute elements is ensured, the abnormal growth of crystal grains is avoided, and the comprehensive performance of the prepared aluminum alloy is further improved.

Fe is an impurity element, which adversely affects the elongation of the aluminum alloy sheet of the present invention, and thus is controlled to 0.2 wt.% or less. Si is a harmful impurity in 5xxx alloys and is susceptible to form Mg with Mg₂Si phase, and because of the higher Mg content in the alloy of the invention, the Mg content is reduced₂The solubility of Si phase in matrix can not only not strengthen but also reduce the plasticity of alloy, so that Si is controlled to be less than or equal to 0.1 wt.%.

According to the invention, through optimizing the main alloy elements and the content of the main alloy elements of the 5xxx series aluminum alloy, the material has remarkable baking and hardening capacity, and the formation of a deformation zone is hindered; and a differential multistage homogenization process is adopted for materials with different Mn contents, so that the solute elements are fully diffused, and the grains are not abnormally grown. The grain size is controlled to be 30-70 mu m through an intermediate annealing and final annealing system, YPE is reduced to 0, and the material has good formability and a surface with high forming quality. Specifically, the alloy strength is improved by increasing the content of Mg; the baking resistance of the alloy is improved by improving the Cu content; strictly controlling the Mn content to improve the forming performance of the alloy, optimizing the rolling and annealing process, simultaneously improving the mechanical property and the forming performance of the alloy, and preparing the 5xxx series alloy with high strength, baking resistance, easy forming, YPE of 0 and good standing stability. In conclusion, the plate has good forming performance before baking, the yield strength is 110-140 MPa, the elongation is larger than or equal to 30%, the strain hardening index is larger than or equal to 0.34, the average plastic strain ratio is larger than or equal to 0.70, the YPE is 0, the standing stability is good, the tensile strength of the alloy after the material is baked is larger than or equal to 300MPa, the yield strength is improved by larger than or equal to 45MPa compared with that before baking, the baking and hardening capacity is remarkable, and the comprehensive performance of the plate is obviously better than that of the existing 5xxx series aluminum alloy material.

By using the two-stage homogenization treatment in the invention, the high-magnesium-containing and high-copper-containing aluminum alloy with high strength can be prepared, specifically, the content of Mg and Cu in the invention exceeds the component system of the existing 5023 aluminum alloy, and the content of Mg exceeds the highest content of Mg in the existing commercial deformation 5-series aluminum alloy, but because the innovative process of the invention promotes the tissue optimization, the material of the invention does not have the phenomenon of Lvdes belt common in the conventional high-Mg material, and in a preferred embodiment, the aluminum alloy comprises the following components in percentage by weight: 5.5-7.5 wt.% of Mg, 0.5-0.6 wt.% of Cu, less than or equal to 0.1 wt.% of Si, 0.1-0.4 wt.% of Fe, 0.05-0.15 wt.% of Mn, less than or equal to 0.05 wt.% of Cr, less than or equal to 0.1 wt.% of Ti, less than or equal to 0.15 wt.% of the total inevitable impurities, and the balance of Al.

More preferably, the aluminum alloy comprises the following components in percentage by weight: mg 6.0 wt.%, Cu 0.3 wt.%, Si 0.08 wt.%, Fe 0.12 wt.%, Mn0.05 wt.%, Cr0.01 wt.%, Ti 0.05 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg 7.1 wt.%, Cu0.15 wt.%, Si 0.08 wt.%, Fe 0.10 wt.%, Mn 0.12 wt.%, Cr0.01 wt.%, Ti 0.10 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg 5.5 wt.%, Cu 0.5 wt.%, Si 0.1 wt.%, Fe 0.12 wt.%, Mn 0.1 wt.%, Cr0.01 wt.%, Ti 0.04 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg 6.0 wt.%, Cu 0.25 wt.%, Si 0.08 wt.%, Fe 0.12 wt.%, Mn 0.08 wt.%, Cr0.01 wt.%, Ti 0.08 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg 5.6 wt.%, Cu 0.35 wt.%, Si 0.10 wt.%, Fe 0.10 wt.%, Mn 0.10 wt.%, Cr0.01 wt.%, Ti 0.05 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg7.5 wt.%, Cu 0.6 wt.%, Si 0.10 wt.%, Fe 0.4 wt.%, Mn 0.15 wt.%, Cr 0.05 wt.%, Ti 0.1 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg5 wt.%, Cu0.15 wt.%, Si 0.10 wt.%, Fe0.1 wt.%, Mn0.05 wt.%, Cr0.01 wt.%, Ti 0.01 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg 7.1 wt.%, Cu0.15 wt.%, Si 0.08 wt.%, Fe 0.10 wt.%, Mn 0.12 wt.%, Cr0.01 wt.%, Ti 0.10 wt.%, and the balance Al; or the aluminum alloy comprises the following components: mg 7.1 wt.%, Cu0.15 wt.%, Si 0.08 wt.%, Fe 0.10 wt.%, Mn 0.12 wt.%, cr 0.01wt.%, Ti 0.10 wt.%, and the balance Al.

In order to further exert the strengthening effect of Mg and Cu and match the recrystallization inhibiting effect of Mn in the alloy, so as to further improve the baking performance of the aluminum alloy plate, in a preferred embodiment, the Mg/Mn ratio in the aluminum alloy is (50-120): 1 by weight percent, and the Cu/Mn ratio in the aluminum alloy is (1-6): 1 by weight percent.

The homogenization treatment is a key factor for controlling the strength and the formability of the high-Mg alloy, can eliminate the microsegregation of Mg element and dissolve the non-equilibrium low-melting eutectic structure; meanwhile, the homogenization treatment can ensure that Mn-containing particles are dispersed and precipitated uniformly, which is beneficial to controlling the crystal grain structure in the rolling process. Generally, the slow heating rate is favorable for promoting the precipitation of dispersed particles, and the beta primary phase is not easy to melt due to the too fast heating rate. In a preferred embodiment, in the first homogenization treatment, the temperature is raised to 430-440 ℃ at a rate of 30-60 ℃/h, and the temperature is maintained for 3-4 h, and then the first homogenization treatment is performed, and then the second homogenization treatment is performed. The purpose of adopting two-stage heating and controlling the heating rate is as follows: eliminating a eutectic phase with a low melting point through first homogenization treatment, promoting nucleation and precipitation of a Mn-containing phase, and preparing for controlling crystal grains in a subsequent deformation process; the second homogenization treatment is performed to dissolve Mg as much as possible₂Si phase and ensures that the alloy does not grow abnormally. Through the collocation of the process parameters, a better homogenization effect can be achieved.

Along with the increase of the content of Mn, the temperature of the abnormal growth of crystal grains is increased, in order to avoid the influence of the large abnormal growth of the crystal grains on the performance of the aluminum alloy plate, in a preferred embodiment, in the second homogenization treatment, when the weight percentage of Mn in the aluminum alloy is 0.05-0.08 wt.%, the temperature is increased to 500-510 ℃ at the speed of 20-30 ℃/h, and the temperature is kept for 4-10 h; when the weight percentage of Mn in the aluminum alloy is 0.1-0.15 wt.%, the temperature is raised to 520-530 ℃ at the rate of 20-30 ℃/h, and the temperature is preserved for 6-10 h.

The control of the initial rolling temperature is beneficial to plastic deformation and the control of the final rolling temperature of the material, if the initial rolling temperature is too low, the hot working performance of the alloy can be reduced, and the phenomena of cracking, edge cracking and the like in the rolling process can be easily caused; and the excessively low finish rolling temperature is not beneficial to improving the forming performance of the subsequent plate, so in a preferred embodiment, the initial rolling temperature of the hot rolling process is controlled to be 460-520 ℃, the finish rolling temperature is more than or equal to 300 ℃, the deformation rate of the cast ingot is 1-3%, and the total deformation is more than or equal to 95%. Under the initial rolling temperature and the final rolling temperature, the deformation process and the subsequent heat treatment process are favorably and smoothly carried out.

The intermediate annealing process is to ensure that the plate is completely recrystallized, and the temperature is not too high so as to prevent secondary recrystallization or severe oxidation of the surface of the plate, and in a preferred embodiment, the temperature of the intermediate annealing process is 280-380 ℃. Too large or too small cold rolling rate can cause large anisotropy of the plate and reduce forming performance, so that the cold rolling reduction rate is controlled to be 30-60% in the cold rolling process.

In a preferred embodiment, the final annealing process adopts continuous annealing, the continuous annealing temperature is 500-550 ℃, and the time is 20-40 s; preferably, the temperature of the continuous annealing is 520-550 ℃. And (3) carrying out final annealing treatment on the plate by adopting a continuous furnace, and rapidly cooling, thereby being beneficial to controlling the grain size to be 30-70 mu m and simultaneously being beneficial to ensuring that the YPE of the plate can be completely eliminated.

In another exemplary embodiment of the invention, a high-forming baking-resistant 5xxx series aluminum alloy sheet is also provided, which is prepared by the preparation method of the invention; preferably, the yield strength of the plate is 110-140 MPa, the elongation is more than or equal to 30%, the strain hardening index is more than or equal to 0.34, the average plastic strain ratio is more than or equal to 0.70, YPE is 0, the stable standing days are more than or equal to 180 days, and the plate has good forming performance.

In a preferred embodiment, after the high-forming baking-resistant 5xxx aluminum alloy plate is subjected to simulated baking finish treatment at 180 ℃/20min, the tensile strength is more than or equal to 300MPa, the yield strength is improved by more than or equal to 45MPa compared with that before baking, and the high-forming baking-resistant 5xxx aluminum alloy plate has good baking resistance.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

Example 1

The aluminum alloy comprises the following components in percentage by mass: mg 6.0 wt.%, Cu 0.3 wt.%, Si 0.08 wt.%, Fe 0.12 wt.%, Mn0.05 wt.%, Cr0.01 wt.%, Ti 0.05 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 2h, then heating to 500 ℃ at a speed of 30 ℃/h, preserving heat for 10h, and then taking out and air-cooling. And heating the ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the final rolling temperature of 300 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 280 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 530 ℃, and immediately performing water quenching after the heat preservation time is 30 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Example 2

The aluminum alloy comprises the following components in percentage by mass: mg 7.1 wt.%, Cu0.15 wt.%, Si 0.08 wt.%, Fe 0.10 wt.%, Mn 0.12 wt.%, Cr0.01 wt.%, Ti 0.10 wt.%, and the balance Al.

The alloy components are cast into a flat ingot by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 4h, then heating to 540 ℃ at a speed of 25 ℃/h, preserving heat for 8h, and then taking out for air cooling. And heating the ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 330 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 350 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 540 ℃, and immediately performing water quenching after the heat preservation time is 45 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Example 3

The aluminum alloy comprises the following components in percentage by mass: mg 5.5 wt.%, Cu 0.5 wt.%, Si 0.1 wt.%, Fe 0.12 wt.%, Mn 0.1 wt.%, Cr0.01 wt.%, Ti 0.04 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot by adopting a two-stage homogenizing process, firstly heating to 420 ℃ at a speed of 30 ℃/h, preserving heat for 2h, then heating to 520 ℃ at a speed of 20 ℃/h, preserving heat for 6h, and then taking out for air cooling. And heating the ingot after surface milling to 520 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 320 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 350 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 60%. And continuously annealing the cold-rolled sheet at 530 ℃, and immediately performing water quenching after the heat preservation time is 30 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Example 4

The aluminum alloy comprises the following components in percentage by mass: mg 6.0 wt.%, Cu 0.25 wt.%, Si 0.08 wt.%, Fe 0.12 wt.%, Mn 0.08 wt.%, Cr0.01 wt.%, Ti 0.08 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 45 ℃/h, preserving heat for 2h, then heating to 510 ℃ at a speed of 20 ℃/h, preserving heat for 4h, and then taking out and air-cooling. And heating the ingot after surface milling to 510 ℃, preserving heat for 3 hours, and carrying out hot rolling at the final rolling temperature of 300 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 330 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 40%. And continuously annealing the cold-rolled sheet at 550 ℃, and immediately performing water quenching after the heat preservation time is 30 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to a 180 ℃/20min (simulated paint bake) artificial aging treatment (BH state), and the performance tests are shown in Table 1.

Example 5

The aluminum alloy comprises the following components in percentage by mass: mg 5.6 wt.%, Cu 0.35 wt.%, Si 0.10 wt.%, Fe 0.10 wt.%, Mn 0.10 wt.%, Cr0.01 wt.%, Ti 0.05 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 430 ℃ at a speed of 60 ℃/h, preserving heat for 3h, then heating to 530 ℃ at a speed of 25 ℃/h, preserving heat for 8h, and then taking out for air cooling. And heating the ingot after surface milling to 515 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 320 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 370 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 550 ℃, and immediately performing water quenching after the heat preservation time is 30 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Example 6

The aluminum alloy comprises the following components in percentage by mass: mg7.5 wt.%, Cu 0.6 wt.%, Si 0.10 wt.%, Fe 0.4 wt.%, Mn 0.15 wt.%, Cr 0.05 wt.%, Ti 0.1 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 4h, then heating to 530 ℃ at a speed of 25 ℃/h, preserving heat for 10h, and then taking out and air-cooling. And heating the cast ingot after surface milling to 520 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 330 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 350 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 540 ℃, and immediately performing water quenching after the heat preservation time is 45 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Example 7

The aluminum alloy comprises the following components in percentage by mass: mg5 wt.%, Cu0.15 wt.%, Si 0.10 wt.%, Fe0.1 wt.%, Mn0.05 wt.%, Cr0.01 wt.%, Ti 0.01 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 4h, then heating to 500 ℃ at a speed of 25 ℃/h, preserving heat for 8h, and then taking out and air-cooling. And heating the ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 330 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 350 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 540 ℃, and immediately performing water quenching after the heat preservation time is 45 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Example 8

The aluminum alloy comprises the following components in percentage by mass: mg 7.1 wt.%, Cu0.15 wt.%, Si 0.08 wt.%, Fe 0.10 wt.%, Mn 0.12 wt.%, Cr0.01 wt.%, Ti 0.10 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 4h, then heating to 520 ℃ at a speed of 30 ℃/h, preserving heat for 12h, and then taking out for air cooling. And heating the ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 330 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 350 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 540 ℃, and immediately performing water quenching after the heat preservation time is 45 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Example 9

The aluminum alloy comprises the following components in percentage by mass: mg 7.1 wt.%, Cu0.15 wt.%, Si 0.08 wt.%, Fe 0.10 wt.%, Mn 0.12 wt.%, Cr0.01 wt.%, Ti 0.10 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, firstly heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 4h, then heating to 560 ℃ at a speed of 40 ℃/h, preserving heat for 12h, and then taking out for air cooling. And heating the ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 330 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 350 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 540 ℃, and immediately performing water quenching after the heat preservation time is 45 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Comparative example 1

The aluminum alloy comprises the following components in percentage by mass: mg 6.0 wt.%, Cu0 wt.%, Si 0.10 wt.%, Fe 0.10 wt.%, Mn0.05 wt.%, Cr0.01 wt.%, and the balance Al.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 2h, then heating to 500 ℃ at a speed of 30 ℃/h, preserving heat for 8h, and then taking out and air-cooling. And heating the cast ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 280 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 330 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 40%. And continuously annealing the cold-rolled sheet at 490 ℃, and immediately performing water quenching after the heat preservation time of 30 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Comparative example 2

The aluminum alloy comprises the following components in percentage by mass: mg 5.6 wt.%, Cu 0.35 wt.%, Si 0.10 wt.%, Fe 0.10 wt.%, Mn 0.08 wt.%, Cr0.01 wt.%, Ti 0.05 wt.%, and the balance Al. The composition of comparative example 2 was identical to example 5, but a different processing procedure was used.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot: keeping the temperature at 500 ℃ for 8h, and then taking out for air cooling. And heating the cast ingot after surface milling to 500 ℃, preserving heat for 2 hours, and carrying out hot rolling at the finishing temperature of 280 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 380 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 30%. And continuously annealing the cold-rolled sheet at the annealing temperature of 500 ℃ for 30s, and immediately performing water quenching. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Comparative example 3

The aluminum alloy comprises the following components in percentage by mass: mg 6.0 wt.%, Cu 0.3 wt.%, Si 0.08 wt.%, Fe 0.12 wt.%, Mn0.05 wt.%, Cr0.01 wt.%, Ti 0.05 wt.%, and the balance Al. The composition of comparative example 3 was identical to example 1, but a different processing procedure was used.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 2h, then heating to 550 ℃ at a speed of 30 ℃/h, preserving heat for 12h, and then taking out for air cooling. And heating the ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the final rolling temperature of 300 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 280 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. Continuously annealing the cold-rolled sheet, wherein the annealing temperature is 530 ℃, and immediately performing water quenching after the heat preservation time is 30 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Comparative example 4

The aluminum alloy comprises the following components in percentage by mass: mg 7.1 wt.%, Cu0.15 wt.%, Si 0.08 wt.%, Fe 0.10 wt.%, Mn 0.12 wt.%, Cr0.01 wt.%, Ti 0.10 wt.%, and the balance Al. The composition of comparative example 4 was identical to example 2, but a different processing procedure was used.

The alloy components are cast into flat ingots by a semi-continuous casting method. Homogenizing the cast ingot, adopting a two-stage homogenizing process, heating to 440 ℃ at a speed of 30 ℃/h, preserving heat for 4h, then heating to 560 ℃ at a speed of 25 ℃/h, preserving heat for 15h, and then taking out and air-cooling. And heating the ingot after surface milling to 500 ℃, preserving heat for 3 hours, and carrying out hot rolling at the finishing temperature of 330 ℃. And (3) cold rolling and intermediate annealing are carried out on the plate, wherein the intermediate annealing adopts box annealing, the temperature is 350 ℃, the heat preservation is carried out for 3h, then the plate after the intermediate annealing is carried out cold rolling, and the cold rolling reduction rate is 50%. And continuously annealing the cold-rolled sheet at 540 ℃, and immediately performing water quenching after the heat preservation time is 45 s. Placing the quenched plate at room temperature for 7 days, and then dividing the plate into two groups, wherein one group is directly stretched (H111 state); the other group was subjected to an artificial aging treatment (BH state) at 180 ℃/20min (simulated baking finish) and the performance tests are shown in Table 1.

Table 1 shows the properties of the alloys in the examples and comparative examples. The tensile strain and tensile stress curve of example 1 is shown in fig. 1, the tensile strain and tensile stress curve of comparative example 1 is shown in fig. 2, the elongation curve of example 1 after 180 days of parking is shown in fig. 3, the strength curve of example 1 after 180 days of parking is shown in fig. 4, the grain pattern of example 1 after the second homogenization treatment corresponding to 0.05 wt.% Mn is shown in fig. 5, and the grain pattern of example 3 after the second homogenization treatment corresponding to 0.1 wt.% Mn is shown in fig. 6.

TABLE 1

As shown in Table 1, compared with a comparative example, the aluminum alloy material with high magnesium content and high copper content is used in the embodiment of the invention, and the aluminum alloy plate prepared by adjusting and matching the preparation process and adopting the corresponding multistage homogenization process aiming at the aluminum alloy materials with different Mn contents has obvious baking hardening capacity, YPE is reduced to 0, so that the material has good forming performance before baking, the yield strength is 110-140 MPa, the elongation is more than or equal to 30%, the strain hardening index is more than or equal to 0.34, the average plastic strain ratio is more than or equal to 0.70, the YPE is 0, the material also has obvious baking hardening capacity, the tensile strength of the alloy after baking is more than or equal to 300MPa, and the yield strength is improved by more than or equal to 45 MPa.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method of making a high-formability bake-resistant 5 xxx-series aluminum alloy sheet, comprising the steps of:

step S1, mixing raw materials of the 5xxx series aluminum alloy and melting and casting ingots to obtain aluminum alloy cast ingots; wherein the aluminum alloy comprises the following components in percentage by weight: 5.0-7.5 wt.% of Mg, 0.15-0.6 wt.% of Cu, less than or equal to 0.1 wt.% of Si, 0.1-0.4 wt.% of Fe, 0.05-0.15 wt.% of Mn, less than or equal to 0.05 wt.% of Cr, less than or equal to 0.1 wt.% of Ti, less than or equal to 0.15 wt.% of the total of inevitable impurities, and the balance of Al;

step S2, performing two-stage homogenization treatment on the aluminum alloy cast ingot, wherein in the two-stage homogenization treatment, the temperature is increased to 420-445 ℃ at the speed of 25-60 ℃/h, the temperature is kept for 2-4 h, the first homogenization treatment is performed, then the temperature is increased to 500-540 ℃ at the speed of 20-30 ℃/h, the temperature is kept for 4-10 h, and the second homogenization treatment is performed;

step S3, carrying out hot rolling on the homogenized cast ingot to obtain a hot rolled plate;

step S4, performing intermediate annealing, cold rolling, final annealing and cooling on the hot rolled plate to obtain the high-forming baking-resistant 5xxx series aluminum alloy;

in the second homogenization treatment, when the weight percentage of Mn in the aluminum alloy is more than or equal to 0.05 wt.% and less than 0.1 wt.%, heating to 500-530 ℃ at the speed of 20-30 ℃/h, and preserving heat for 4-10 h; when the weight percentage of Mn in the aluminum alloy is more than or equal to 0.1 wt.% and less than 0.15 wt.%, heating to 520-540 ℃ at the speed of 20-30 ℃/h, and preserving heat for 6-10 h.

2. The method according to claim 1, wherein the aluminum alloy comprises, in weight percent: 5.5-7.5 wt.% of Mg, 0.5-0.6 wt.% of Cu, less than or equal to 0.1 wt.% of Si, 0.1-0.4 wt.% of Fe, 0.05-0.15 wt.% of Mn, less than or equal to 0.05 wt.% of Cr, less than or equal to 0.1 wt.% of Ti, less than or equal to 0.15 wt.% of the total inevitable impurities, and the balance of Al.

3. The method according to claim 1 or 2, wherein the aluminum alloy has a ratio of Mg/Mn (50-120): 1, in weight percent, and Cu/Mn (1-6): 1, in weight percent.

4. The method according to any one of claims 1 to 3, wherein the temperature is raised to 430 to 440 ℃ at a rate of 30 to 60 ℃/h and the temperature is maintained for 3 to 4h in the first homogenization treatment.

5. The preparation method according to any one of claims 1 to 4, wherein in the second homogenization treatment, when the weight percentage of Mn in the aluminum alloy is 0.05 to 0.08 wt.%, the temperature is raised to 500 to 510 ℃ at a rate of 20 to 30 ℃/h, and the temperature is maintained for 4 to 10 h; when the weight percentage of Mn in the aluminum alloy is 0.1-0.15 wt.%, heating to 520-530 ℃ at the speed of 20-30 ℃/h, and preserving heat for 6-10 h.

6. The production method according to any one of claims 1 to 5, wherein the hot rolling process is performed at a start rolling temperature of 460 to 520 ℃, a finish rolling temperature of 300 ℃ or higher, a deformation rate of the ingot of 1 to 3%, and a total deformation amount of 95% or higher.

7. The method for preparing the silicon carbide ceramic according to any one of claims 1 to 6, wherein the temperature of the intermediate annealing process is 280-380 ℃; in the cold rolling process, the cold rolling reduction rate is 30-60%.

8. The preparation method according to any one of claims 1 to 7, wherein the final annealing process adopts continuous annealing, the continuous annealing temperature is 500-550 ℃, and the time is 20-40 s; preferably, the temperature of the continuous annealing is 520-550 ℃.

9. A high-formability baking-resistant 5 xxx-series aluminum alloy sheet, prepared by the method of any one of claims 1 to 8; preferably, the yield strength of the high-forming baking-resistant 5xxx series aluminum alloy plate is 110-140 MPa, the elongation is not less than 30%, the strain hardening index is not less than 0.34, the average plastic strain ratio is not less than 0.70, YPE is 0, and the stable standing days are not less than 180 days.

10. The high-formability baking-resistant 5xxx series aluminum alloy sheet of claim 9, wherein the tensile strength of the high-formability baking-resistant 5xxx series aluminum alloy sheet is not less than 300MPa after the high-formability baking-resistant 5xxx series aluminum alloy sheet is subjected to simulated paint baking treatment at 180 ℃/20min, and the yield strength is improved by not less than 45MPa compared with that before baking.

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