Aluminum alloy strip and preparation method thereof

Abstract

The invention provides an aluminum alloy strip and a preparation method thereof.The preparation method comprises the following steps that a raw material formula serves as a melt to be smelted into molten aluminum, the molten aluminum is guided into a standing furnace, after the molten aluminum is guided into the standing furnace, grain refinement treatment is conducted on the molten aluminum, and during grain refinement treatment, aluminum-titanium-boron wires are continuously and reversely added into an outlet of the standing furnace; the molten aluminum flowing out of the standing furnace is firstly subjected to degassing treatment by adopting a degassing box, then the degassed molten aluminum is filtered by adopting a filtering box, and then cast rolling is performed to obtain a cast-rolled plate; the cast-rolled plate is subjected to cold rolling treatment, and an aluminum strip is obtained; the aluminum strip is cleaned, and an aluminum blank is obtained; and the aluminum blank is subjected to annealing treatment, and the aluminum alloy strip is obtained. Compared with the prior art, the high-reflection mirror surface has the characteristic of high-reflection mirror surface, and the heat reflection prevention capability is greatly improved; the aluminum alloy strip has good punch forming performance, the index shows that the aluminum alloy strip has a high cupping value and a low earing rate, and meanwhile the aluminum alloy strip still keeps good plasticity at the low temperature.

Description

Technical Field

[0001] The present invention is applicable to the technical field of aluminum processing, and in particular relates to an aluminum alloy strip material used for making heat shields such as automobile engines and a preparation method thereof. Background Art

[0002] Automobile heat shield refers to the parts installed around the engine and above the chassis exhaust system. It can effectively isolate heat transfer, reduce the temperature around the engine, chassis and in the cab, protect the normal operation of electronic components near the engine and chassis, reduce vibration and shock, and improve driving comfort. At the same time, because the design and installation of the heat shield need to be coordinated with the exhaust system and the chassis shape structure, the overall size of the heat shield is large and there are many free-form surfaces. It has the characteristics of obvious height fluctuations, and it is easy to have local wrinkles and deep drawing cracks during forming. At present, the lightweight engine and turbocharging technology require more efficient and lighter heat insulation products to protect the heat-sensitive electronic components and other heat-sensitive parts in the engine compartment.

[0003] Aluminum alloy materials have the following advantages and are very suitable for use as thermal insulation materials: 1. Sound absorption, can be used to make various damping materials and shock-absorbing components; 2. Good reflection performance for light, heat, and radio waves; 3. Good electrical and thermal conductivity; 4. Corrosion resistance, low density, and high specific strength.

[0004] In the early days, some heat shield materials were made by stamping cold-rolled steel plates or hot-dip aluminum / chrome-plated steel plates, which had poor forming properties and were prone to wrinkling and cracking due to stamping. Today, most heat shield materials use the hot rolling method to produce 1050 alloy for heat shields, but there are problems such as long process flow and low yield rate. Some companies also use the casting and rolling method to produce 1050 alloy for heat shields, but its 0.5mm thickness elongation is only 33%, the earing rate is 2.6, and the heat insulation effect is poor.

[0005] Therefore, there is an urgent need for a new aluminum alloy strip and a preparation method thereof to solve the above-mentioned technical problems. Summary of the invention

[0006] The present invention provides an aluminum alloy strip and a preparation method thereof, aiming to provide an aluminum alloy strip with high deep drawing forming performance, high surface glossiness and low production cost, so as to be suitable for a heat insulation screen.

[0007] In a first aspect, the present invention provides a method for preparing an aluminum alloy strip, the preparation method comprising the following steps:

[0008] S1. Prepare a melt according to the following raw material formula and smelt it into aluminum liquid, and introduce the aluminum liquid into a static furnace for static placement;

[0009] The components and mass percentages of the raw material formula are: Si=0.02-0.10wt%, Fe=0.12-0.25wt%, Cu=0.04-0.05wt%, Mn≤0.01wt%, Mg≤0.01wt%, Zn≤0.02wt%, B≤0.003wt%, Ti≤0.01wt%, V≤0.01wt%, C≤0.001wt%, unavoidable impurities are less than or equal to 0.05%, and the balance is Al;

[0010] The Fe element is added in the form of potassium fluoroaluminate iron agent, and the composition and mass percentage of the potassium fluoroaluminate iron agent are: 80% iron powder and 20% potassium fluoroaluminate; copper is added in the form of aluminum-copper alloy; the Ti element is added in the form of aluminum-titanium-boron wire as a grain refiner continuously added in reverse to the outlet of the static furnace during the pouring of the furnace, and the addition amount of the aluminum-titanium-boron wire is 1.4-1.6 kg / t Al;

[0011] S2, using a degassing box to degas the aluminum liquid poured out from the static furnace, and then using a filter box to filter the degassed aluminum liquid, and then casting and rolling to obtain a cast-rolled plate with a thickness of 6.0 to 7.2 mm; wherein the length of the casting and rolling zone is 50 to 65 mm;

[0012] S3, cold rolling the cast-rolled plate to obtain an aluminum strip;

[0013] S4, cleaning the aluminum strip to obtain an aluminum billet;

[0014] S5. Annealing the aluminum billet to obtain an aluminum alloy strip.

[0015] Preferably, in step S1, when the melt is being melted, the temperature of the melt is 730-750° C., and nitrogen or argon is introduced for refining for 12-30 minutes.

[0016] Preferably, in step S2, argon gas is blown into the degassing box by a rotary blowing method for degassing, and the hydrogen content in the aluminum liquid after degassing is less than 0.12 ml / 100 g Al.

[0017] Preferably, step S3 includes the following sub-steps:

[0018] Performing a first cold rolling process on the cast-rolled plate to obtain a first cold rolled plate with a thickness of 1.5 to 3.0 mm;

[0019] Performing an intermediate annealing treatment on the first cold-rolled sheet at a temperature of 300 to 420° C. for a time of 1 to 3 hours;

[0020] Performing a second cold rolling process on the first cold-rolled sheet after the intermediate annealing process to obtain an aluminum strip with a thickness of 0.2 to 0.8 mm;

[0021] The cold rolling process is carried out at a medium temperature, the temperature range of the medium temperature rolling is 80-200°C, and the temperature of the aluminum strip after the second cold rolling treatment is controlled at 80-200°C.

[0022] Preferably, in step S3, the cold rolling process is performed by a four-roll irreversible cold rolling mill, and the cold rolling roll of the last pass is polished by a mirror vibration polishing method, and the roll roughness of the cold rolling roll of the last pass is made less than 0.005 μm.

[0023] Preferably, step S4 includes the following sub-steps:

[0024] Performing a flowing water washing treatment on the aluminum strip;

[0025] The aluminum strip after the flowing water washing treatment is subjected to an alkali washing treatment, the pressure during the alkali washing treatment is 4-6 MPa, and the alkali washing liquid used in the alkali washing treatment includes 1‰ phosphine sulfonic acid;

[0026] Rinse the aluminum strip after alkali washing;

[0027] The aluminum strip after rinsing is dried with hot air at 150°C to obtain a surface residual oil content of less than 1 mg / m 2 And the aluminum powder residue is less than 2mg / m 2 of the aluminum billet.

[0028] Preferably, in step S5, the annealing treatment includes two final product annealings, the final product annealing process temperature is 370° C., and the holding time is 2 hours.

[0029] Preferably, in step S5, the annealing treatment is performed using negative pressure noble gas protection annealing, and the noble gas is argon or helium.

[0030] Preferably, the cupping value of the aluminum alloy strip is greater than 9.0 mm.

[0031] In a second aspect, the present invention further provides an aluminum alloy strip, which is made by the method for preparing the aluminum alloy strip described in any one of the above embodiments and is used for a heat shield.

[0032] Compared with the prior art, the present invention adopts a short-process, low-cost cast-rolled aluminum strip process to replace the hot-rolled aluminum strip process, which greatly reduces the production cost. The aluminum alloy strip obtained by cast-rolling retains a large amount of supersaturated solid solution inside. Compared with the aluminum alloy strip obtained by hot rolling, the recrystallization temperature of the material can be increased, and it is not easy to soften at high temperature, which is beneficial to improving the thermal insulation performance of the aluminum alloy strip. By controlling the trace elements in the raw material formula and adopting the mirror vibration polishing method, the obtained aluminum alloy strip has the characteristics of a high reflective mirror surface, which greatly improves the heat reflection resistance. By controlling the cold rolling temperature during the cold rolling process, the aluminum alloy strip has good stamping forming performance, which is reflected in the indicators of high cupping value and low ear making rate. At the same time, the aluminum alloy strip still maintains good plasticity at low temperature, and its tensile strength, yield strength, elastic modulus, elongation and toughness are improved as the temperature decreases. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be described in detail below in conjunction with the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made in conjunction with the following drawings. In the accompanying drawings:

[0034] Figure 1 It is a flowchart of a method for preparing an aluminum alloy strip provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] Embodiment 1

[0037] Please refer to Figure 1 The present invention provides a method for preparing an aluminum alloy strip, the preparation method comprising the following steps:

[0038] S1. The following raw material formula is used as a melt and smelted into aluminum liquid, and the aluminum liquid is introduced into a static furnace for static placement. After the aluminum liquid is introduced into the static furnace, the aluminum liquid is subjected to a grain refinement treatment. During the grain refinement treatment, aluminum titanium boron wire is continuously added in reverse to the outlet of the static furnace;

[0039] The components and mass percentages of the raw material formula are: Si=0.02-0.10wt%, Fe=0.12-0.25wt%, Cu=0.04-0.05wt%, Mn≤0.01wt%, Mg≤0.01wt%, Zn≤0.02wt%, B≤0.003wt%, Ti≤0.01wt%, V≤0.01wt%, C≤0.001wt%, unavoidable impurities are less than or equal to 0.05wt%, and the balance is Al.

[0040] The Fe element is added in the form of a potassium fluoroaluminate iron agent, and the composition and mass percentage of the potassium fluoroaluminate iron agent are: 80% iron powder and 20% potassium fluoroaluminate; copper is added in the form of an aluminum-copper alloy; the Ti element is added in the form of aluminum-titanium-boron wire as a grain refiner continuously added to the outlet of the static furnace in reverse direction during the pouring of the furnace, and the addition amount of the aluminum-titanium-boron wire is 1.4-1.6 kg / t Al, and the aluminum-titanium-boron wire is AlTi 5 B 0.2 Al inside 3 Ti and TiB 2 The particles are high melting point compounds that can serve as cores for grain formation.

[0041] In the embodiment of the present invention, in step S1, preferably, the components and mass percentages of the raw material formula are: Si = 0.02-0.08wt%, Fe = 0.15-0.22wt%, Cu = 0.04-0.05wt%, Mn ≤ 0.005wt%, Mg ≤ 0.005wt%, Zn ≤ 0.02wt%, B ≤ 0.001wt%, Ti ≤ 0.01wt%, V ≤ 0.01wt%, C ≤ 0.001wt%, unavoidable impurities are less than or equal to 0.05%, and the balance is Al. When the melt is smelted, the spray stirring smelting technology is adopted to ensure heating and stirring while not destroying the surface oxide film, so as to obtain a purified melt, the temperature of the melt is 730-750°C, and nitrogen or argon is introduced for refining for 12-30min.

[0042] Specifically, in the raw material formula, the iron agent is added in the form of potassium fluoroaluminate type iron agent, which contains 80% iron powder and 20% potassium fluoroaluminate as additives. Potassium fluoroaluminate not only plays the role of fluxing iron powder, but also plays the role of refining, and can form a fluoride protective film on the surface of aluminum melt. This protective film can withstand high temperatures of up to 800 degrees Celsius for hundreds of hours without oxidation, greatly reducing the generation of oxide slag inclusions. At the same time, the fluoride can produce a replacement reaction between the alkali metal elements and the alkaline earth metals Li, Na, and K elements in the aluminum water to generate salts, which are finally scraped out in the form of slag. The copper in this scheme is added in the form of aluminum-copper alloy. In summary, the salt slag inclusions caused by refining agents and fluxes such as sodium chloride, magnesium chloride, and potassium chloride can be greatly reduced.

[0043] In order to further improve the formability of the material, the upper limit of the Si content contained in the aluminum alloy is preferably listed as less than about 0.10wt% (i.e. Si = 0.02~0.10wt%), and more preferably listed as less than about 0.08wt% (i.e. Si = 0.02~0.08wt%); when the amount of Si added is large, this will form more silicon-aluminum alloy phases such as eutectic silicon and coarse-crystalline silicon, and silicon and iron form at the same time. These phases exist as hard points in the aluminum alloy, which will hinder the movement of dislocations and make plastic deformation difficult. Excessive amount will cause the compound size to coarsen and the distribution density to decrease, and the uniformity of the recrystallized grain size distribution after final annealing will be reduced.

[0044] Copper is an element that significantly increases the strength of the aluminum strip, has a work hardening effect, and reduces the elongation of the aluminum strip. Since the method requires two complete annealing treatments in the subsequent step S5, it is necessary to add certain strengthening elements, and at the same time ensure that the aluminum content of the chemical composition is greater than 99.50%. Therefore, the Cu content is preferably 0.04-0.05wt%.

[0045] In order to ensure the aluminum content in the aluminum alloy, the upper limit of the Fe content in the 1350 aluminum alloy is preferably about 0.25wt% or less, and the lower limit is preferably about 0.12wt% or more (i.e., Fe = 0.12-0.25wt%), and more preferably about 0.22wt% or less and about 0.15wt% or more (i.e., Fe = 0.15-0.22wt%). The solid solubility of iron in aluminum is 0.05%. During the casting process, the excess Fe crystallizes into Al 3 Fe-based intermetallic compounds, when the compound size is large, become recrystallization nucleation points during the annealing process, and therefore have the effect of refining the recrystallized grains and have a particle-induced nucleation effect. When the Fe content is less than the lower limit, the distribution density of the coarse intermetallic compounds decreases, the refinement effect is weak, and the final grain size distribution becomes uneven. When the Fe content is greater than the upper limit, it is easy to cause insufficient final purity, so the Fe content is adjusted within the above range.

[0046] In order to improve the processing and forming properties of aluminum strip, a small amount of manganese in 1350 aluminum is dissolved in the aluminum matrix to inhibit the recrystallization of aluminum. When Mn is in a very trace state, it can produce a work hardening effect similar to Cu; however, when the content of Mn is large, it is easy to cause dendrite segregation, delay recrystallization during intermediate annealing and final annealing, and it is difficult to obtain uniform fine grains. Therefore, the content of Mn is adjusted to 0.01wt% or less (i.e., Mn≤0.01wt%). For reasons similar to the above, the upper limit of the Mn content is more preferably set to 0.005% by mass (i.e., Mn≤0.005wt%).

[0047] In order to further improve the formability of the aluminum alloy strip as a heat shield, the upper limit of the V content is preferably listed as less than about 0.01wt% (i.e. V≤0.01wt%). When the V content is large, coarse compounds will be formed, causing deep drawing cracking of the aluminum strip.

[0048] In order to improve the processing and forming properties of aluminum alloy strips, a small amount of magnesium in 1350 aluminum is fixed in the aluminum matrix, which can produce a work hardening effect similar to Cu; however, when the Mg content is large, the difficulty of rolling processing is increased, and the elongation of the final product drops sharply. Therefore, the Mg content is adjusted to 0.01wt% or less (i.e., Mg≤0.01wt%). For reasons similar to the above, the upper limit of the Mg content is more preferably set to 0.005% by mass (i.e., Mg≤0.005wt%).

[0049] In order to reduce the stamping cracking of aluminum alloy strips, the B element in the original aluminum ingot or electrolytic aluminum water must be controlled. This element is related to the Al in the aluminum-titanium-boron refiner added during grain refinement. 3 Ti undergoes peritectic reaction to form coarse titanium aggregates, and the grain refining effect is weakened. Therefore, the content of B is adjusted to less than 0.003wt% (i.e., B≤0.003wt%) by mass or less, and more preferably less than 0.001wt% (i.e., B≤0.001wt%).

[0050] In order to reduce the stamping cracking of aluminum alloy strips, the C element in the original aluminum ingot or electrolytic aluminum water must be controlled. C and aluminum form a high melting point compound Al4C3, which gradually breaks into stamping cracks during the subsequent deep drawing process of the aluminum strip. Therefore, the C content is adjusted to less than 0.003wt% (i.e., C≤0.003wt%), and more preferably less than 0.001wt% (i.e., C≤0.001wt%).

[0051] In order to further improve the formability of the aluminum alloy strip, the upper limit of the average grain size of the aluminum alloy strip is preferably about 40.0 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

[0052] S2. Degassing the aluminum liquid poured out from the static furnace using a degassing box, filtering the degassed aluminum liquid using a filter box, and then casting and rolling to obtain a cast-rolled plate with a thickness of 6.0 to 7.2 mm; wherein the length of the casting and rolling zone is 50 to 65 mm.

[0053] In the embodiment of the present invention, in step S2, the filter box uses a 40+60 mesh plate to filter impurities in the aluminum liquid, and a rotary spray method is used to blow argon into the degassing box for degassing. After degassing, the hydrogen content in the aluminum liquid is less than 0.12ml / 100g Al.

[0054] S3, cold rolling the cast-rolled plate to obtain an aluminum strip.

[0055] In the embodiment of the present invention, the mass ratio of titanium in the aluminum liquid is 0.006-0.01%wt, and step S3 includes the following sub-steps:

[0056] Performing a first cold rolling process on the cast-rolled plate to obtain a first cold rolled plate with a thickness of 1.5 to 3.0 mm;

[0057] Performing an intermediate annealing treatment on the first cold-rolled sheet at a temperature of 300-420° C. for 1-3 hours;

[0058] The first cold-rolled sheet after the intermediate annealing treatment is subjected to a second cold rolling treatment to obtain an aluminum strip with a thickness of 0.2-0.8 mm; wherein the cold rolling process maintains medium-temperature rolling, the temperature range of the medium-temperature rolling is 80-200°C, and the temperature of the aluminum strip after the second cold rolling treatment is 80-200°C.

[0059] Specifically, since the cast-rolled plate is cold-rolled by medium-temperature rolling (i.e., the first cold-rolling treatment and the second cold-rolling treatment at 80 to 200°C), the plasticity of the metal material can be significantly improved, and it is easier to deform during the rolling process than the existing cold rolling, reducing the risk of cracks and fractures; it can promote the grain refinement of the material, thereby improving the strength and hardness of the material, and the material after grain refinement can obtain better mechanical properties during the subsequent heat treatment process. During the medium-temperature rolling process, the deformation resistance of the material is low, so that the rolling speed can be faster, thereby improving production efficiency; medium-temperature rolling can reduce oxidation and corrosion on the metal surface and improve the surface quality of the material. Medium-temperature rolling helps to reduce defects such as holes and cracks inside the material and improve the overall performance of the material. Medium-temperature rolling can adjust the grain size and distribution of the material, make the material structure more uniform, and help improve the comprehensive performance of the material.

[0060] In an embodiment of the present invention, in step S3, cold rolling is performed by a four-roll irreversible cold rolling mill, and the cold rolling roll of the last pass is polished by a mirror vibration polishing method; wherein the roughness of the cold rolling roll of the last pass of the four-roll irreversible cold rolling mill is less than 0.005 μm.

[0061] The cold rolling process of the four-roll irreversible cold rolling mill is divided into rough rolling and finish rolling, with rough rolling first and finish rolling later. In order to obtain high-surface aluminum strip products, in addition to the control of rolling parameters and rolling oil parameters, nylon brush rollers are installed above and below the working rolls. During rolling, they rotate in the opposite direction to the rolls to remove foreign matter on the rolls. The rolling oil is used to wash away the debris adhering to the aluminum plate under high pressure, and finally a high-surface cold-rolled billet is obtained. The accumulated impurities are filtered out in the rolling oil filtration circulation system.

[0062] In order to obtain high-surface aluminum strip products during the aluminum strip rolling process, the rollers in contact with the aluminum strip are imported from Slovenia Simasca and equipped with modern German Hercules CNC grinders to avoid surface spiral lines, vibration lines, horizontal scratches and other defects that affect the surface quality of the aluminum strip caused by poor roller grinding. After the roller grinding is completed, the mirror vibration polishing technology is used to polish the last aluminum strip working roller into a mirror surface. The roller roughness Ra of the four-roll irreversible cold rolling mill is less than 0.005μm. The aluminum strip rolling process is controlled at a low speed, the oil film between the rollers is thin, the aluminum strip surface is closer to the roller surface, and the rolled aluminum strip has good brightness.

[0063] S4, cleaning the aluminum strip to obtain an aluminum billet.

[0064] In the embodiment of the present invention, step S4 includes the following sub-steps:

[0065] Performing a flowing water washing treatment on the aluminum strip;

[0066] The aluminum strip after the flowing water washing treatment is subjected to alkali washing treatment, the pressure during the alkali washing treatment is 4-6MPa, and the alkali washing liquid used in the alkali washing treatment includes 1‰ phosphine sulfonic acid; adding about 1‰ phosphine sulfonic acid can prevent Al 2 O 3 .H 2 O (hydrated oxide film) prevents the formation of alkali slag and obtains a matte surface of aluminum.

[0067] Rinse the aluminum strip after alkali washing;

[0068] The aluminum strip after rinsing is dried with hot air at 150° C. to obtain the aluminum billet with a surface residual oil content of less than 1 mg / ㎡ and an aluminum powder residue of less than 2 mg / ㎡.

[0069] S5. Annealing the aluminum billet to obtain an aluminum alloy strip.

[0070] In an embodiment of the present invention, in step S5, the annealing treatment includes two finished product annealings, the temperature of the finished product annealing process is 370°C, and the holding time is 2 hours. Two annealings can eliminate anisotropy (reduce the earing rate). During the processing, the aluminum alloy may be anisotropic, that is, the performance of the material in different directions is inconsistent. Two annealings can effectively eliminate this anisotropy, so that the performance of the material in different directions is more consistent. Two annealings simultaneously improve the uniformity of the material. The first annealing can release the stress inside the material and make the chemical composition more uniform, while the second annealing can further improve the uniformity of the material's organization, so that the grain size and distribution inside the material are more consistent. Two annealings can also effectively eliminate the residual stress inside the material, improve the plasticity and toughness of the material, make the material easier to deform in the subsequent processing, and reduce the cracks and fractures in the processing. Through two annealings, the mechanical properties of the aluminum alloy can be made more stable and reliable, and the grains can be made more uniform and fine. The first annealing helps to eliminate work hardening, while the second annealing helps to further improve the elongation of the material.

[0071] The annealing treatment adopts negative pressure noble gas protection annealing, and the noble gas is argon or helium. Adopting negative pressure noble gas protection annealing can prevent surface oxidation and oil spots, and finally obtain a fully annealed aluminum strip, and finally obtain mechanical properties that meet deep drawing and forming. The noble gas can be argon and helium.

[0072] In an embodiment of the present invention, the cupping value of the aluminum alloy strip is greater than 9.0 mm.

[0073] In order to better reflect the technical effect of the present invention, the above raw material formula is given as an example, as follows:

[0074] The product thickness of aluminum alloy strip is 0.27-0.8mm. The cast-rolled coil with a thickness of about 7mm needs to be rolled to an intermediate thickness of 1.45mm through a cold rolling mill, and then subjected to intermediate annealing heat treatment to soften it. Finally, the intermediate thickness is rolled to the finished product thickness. The finished product is annealed to obtain the aluminum alloy strip in the required heat treatment state.

[0075] Table 1: Test results of aluminum alloy strip obtained according to the steps of the present invention

[0076]

[0077] According to Table 1, the aluminum alloy strip prepared by the method for preparing the aluminum alloy strip proposed in the present invention has the characteristics of a highly reflective mirror surface, which greatly improves the heat reflection resistance; by controlling the cold rolling temperature during the cold rolling process, the aluminum alloy strip has good stamping forming performance, which is reflected in the indicators of a high cupping value and a low earing rate, and at the same time, the aluminum alloy strip still maintains good plasticity at low temperatures, and its tensile strength, yield strength, elastic modulus, elongation and toughness are all improved as the temperature decreases.

[0078] Compared with the prior art, the present invention adopts a short-process, low-cost cast-rolled aluminum strip process to replace the hot-rolled aluminum strip process, which greatly reduces the production cost. The aluminum alloy strip obtained by cast-rolling retains a large amount of supersaturated solid solution inside. Compared with the aluminum alloy strip obtained by hot rolling, the recrystallization temperature of the material can be increased, and it is not easy to soften at high temperature, which is beneficial to improving the thermal insulation performance of the aluminum alloy strip. By controlling the trace elements in the raw material formula and adopting the mirror vibration polishing method, the obtained aluminum alloy strip has the characteristics of a high reflective mirror surface, which greatly improves the heat reflection resistance. By controlling the cold rolling temperature during the cold rolling process, the aluminum alloy strip has good stamping forming performance, which is reflected in the indicators of high cupping value and low ear making rate. At the same time, the aluminum alloy strip still maintains good plasticity at low temperature, and its tensile strength, yield strength, elastic modulus, elongation and toughness are improved as the temperature decreases.

[0079] Embodiment 2

[0080] An embodiment of the present invention further provides an aluminum alloy strip, which is made by the aluminum alloy strip preparation method described in any one of the above embodiments, and is used for a heat insulation screen and can achieve the same technical effect. Please refer to the description in the above embodiments and will not be repeated here.

[0081] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0082] The embodiments of the present invention are described above in conjunction with the accompanying drawings. What is disclosed is only the preferred embodiment of the present invention. However, the present invention is not limited to the above-mentioned specific implementation manner. The above-mentioned specific implementation manner is only illustrative rather than restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many equivalent changes without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A method for preparing an aluminum alloy strip, characterized in that: The preparation method comprises the following steps: S1. Prepare a melt according to the following raw material formula and smelt it into aluminum liquid, and introduce the aluminum liquid into a static furnace for static placement; The components and mass percentages of the raw material formula are: Si=0.02-0.10wt%, Fe=0.12-0.25wt%, Cu=0.04-0.05wt%, Mn≤0.01wt%, Mg≤0.01wt%, Zn≤0.02wt%, B≤0.003wt%, Ti≤0.01wt%, V≤0.01wt%, C≤0.001wt%, unavoidable impurities are less than or equal to 0.05wt%, and the balance is Al; The Fe element is added in the form of potassium fluoroaluminate iron agent, and the composition and mass percentage of the potassium fluoroaluminate iron agent are: 80% iron powder and 20% potassium fluoroaluminate; copper is added in the form of aluminum-copper alloy; the Ti element is added in the form of aluminum-titanium-boron wire as a grain refiner continuously added in reverse to the outlet of the static furnace during the pouring of the furnace, and the addition amount of the aluminum-titanium-boron wire is 1.4-1.6 kg / t Al; S2, using a degassing box to degas the aluminum liquid poured out from the static furnace, and then using a filter box to filter the degassed aluminum liquid, and then casting and rolling to obtain a cast-rolled plate with a thickness of 6.0 to 7.2 mm; wherein the length of the casting and rolling zone is 50 to 65 mm; S3, cold rolling the cast-rolled plate to obtain an aluminum strip; S4, cleaning the aluminum strip to obtain an aluminum billet; S5. Annealing the aluminum billet to obtain an aluminum alloy strip.

2. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: In step S1, when the melt is being melted, the temperature of the melt is 730-750° C., and nitrogen or argon is introduced for refining for 12-30 minutes.

3. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: In step S2, argon gas is blown into the degassing box by a rotary blowing method for degassing, and the hydrogen content in the aluminum liquid is less than 0.12 ml / 100 gAl after degassing.

4. The method for preparing an aluminum alloy strip according to claim 1, wherein: Step S3 includes the following sub-steps: Performing a first cold rolling process on the cast-rolled plate to obtain a first cold rolled plate with a thickness of 1.5 to 3.0 mm; Performing an intermediate annealing treatment on the first cold-rolled sheet at a temperature of 300 to 420° C. for a time of 1 to 3 hours; Performing a second cold rolling process on the first cold-rolled sheet after the intermediate annealing process to obtain an aluminum strip with a thickness of 0.2 to 0.8 mm; The cold rolling process is carried out at a medium temperature, the temperature range of the medium temperature rolling is 80-200°C, and the temperature of the aluminum strip after the second cold rolling treatment is controlled at 80-200°C.

5. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: In step S3, cold rolling is performed by a four-roll irreversible cold rolling mill, and the cold rolling roll of the last pass is polished by a mirror vibration polishing method, and the roll roughness of the cold rolling roll of the last pass is made less than 0.005 μm.

6. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: Step S4 includes the following sub-steps: Performing a flowing water washing treatment on the aluminum strip; The aluminum strip after the flowing water washing treatment is subjected to an alkali washing treatment, the pressure during the alkali washing treatment is 4-6 MPa, and the alkali washing liquid used in the alkali washing treatment includes 1‰ phosphine sulfonic acid; Rinse the aluminum strip after alkali washing; The aluminum strip after rinsing is dried with hot air at 150°C to obtain a surface residual oil content of less than 1 mg / m 2 And the aluminum powder residue is less than 2mg / m 2 of the aluminum billet.

7. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: In step S5, the annealing treatment includes two final product annealings, the final product annealing process temperature is 370°C, and the holding time is 2 hours.

8. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: In step S5, the annealing process is performed by using negative pressure noble gas protection annealing, and the noble gas is argon or helium.

9. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: The cupping value of the aluminum alloy strip is greater than 9.0 mm.

10. An aluminum alloy strip, characterized in that: The aluminum alloy strip is made by the method for preparing the aluminum alloy strip according to any one of claims 1 to 9, and is used for a heat shield.

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