阅读说明：本技术 一种车用高光铝合金外饰件板材的制备方法 (Preparation method of automotive high-gloss aluminum alloy exterior trim plate ) 是由 江涛 倪慨宇 于 2020-10-23 设计创作，主要内容包括：本发明公开了一种车用高光铝合金外饰件板材的制备方法,其化学成分的质量百分比为:Si为0.02-0.05％,Fe为0.01-0.04％,Cu为0.002-0.005％,Mn为0-0.002％,Mg为0.6-1.0％,Cr为0-0.008％,Zn为0-0.006％,Ti为0.01-0.03％,其余余量为Al。本发明通过成分控制,制备工艺、氧化工艺调控,成品组织控制的方法来制备汽车装饰件,在整个流程中,铸造冷却、热轧工艺、冷轧工艺以及热处理工艺同时实现了组织均匀化控制和表面均匀化控制,可在最大程度实现了成分均匀化以及组织均匀化,为后续获得良好氧化膜层以及高光效果奠定了坚实的基础。(The invention discloses a preparation method of a vehicle highlight aluminum alloy exterior trimming part plate, which comprises the following chemical components, by mass, 0.02-0.05% of Si, 0.01-0.04% of Fe, 0.002-0.005% of Cu, 0-0.002% of Mn, 0.6-1.0% of Mg, 0-0.008% of Cr, 0-0.006% of Zn, 0.01-0.03% of Ti, and the balance of Al. The automobile decoration part is prepared by the method of component control, preparation process, oxidation process regulation and control and finished product structure control, in the whole process, the casting cooling, hot rolling process, cold rolling process and heat treatment process simultaneously realize structure homogenization control and surface homogenization control, can realize component homogenization and structure homogenization to the maximum extent, and lays a solid foundation for obtaining a good oxidation film layer and a high light effect subsequently.)

1. A preparation method of a vehicle highlight aluminum alloy exterior trimming part plate is characterized by comprising the following steps: the method comprises the following steps:

1) casting ingots: adding an aluminum ingot, an aluminum intermediate alloy ingot, a magnesium ingot and a manganese agent into a smelting furnace in proportion, melting, refining, deslagging and stirring, and then placing formed aluminum liquid into a standing furnace for standing; filtering the molten aluminum at 700 ℃, adding a grain refiner into the molten aluminum, refining by argon, and casting the refined molten aluminum into a flat aluminum alloy ingot by a semi-continuous casting method;

2) homogenizing cast ingots: sawing the head and the tail of the flat aluminum alloy cast ingot after heat preservation treatment, milling the surface, and then feeding the flat aluminum alloy cast ingot into a heating furnace for homogenization treatment;

3) hot rolling the ingot blank discharged from the furnace, then rolling, intermediate annealing, and finally cold rolling again to obtain an aluminum alloy plate;

4) and (3) carrying out stretching and straightening on the strip obtained after cleaning, oil removing, finished product annealing, cutting, punch forming, mechanical polishing and anodic oxidation on the strip on a stretching-bending straightening machine to obtain a strip with a better plate shape, thus obtaining the automotive high-gloss aluminum alloy exterior trimming part plate.

2. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: the automotive high-gloss aluminum alloy exterior trimming part plate comprises, by mass, 0.02-0.05% of Si, 0.01-0.04% of Fe, 0.002-0.005% of Cu, 0-0.002% of Mn, 0.6-1.0% of Mg, 0-0.008% of Cr, 0-0.006% of Zn, 0.01-0.03% of Ti, no more than 0.01% of other single impurities, and the balance of Al.

3. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: in the step 1), the thickness of the aluminum alloy flat ingot is 400-450mm, and the filtering specifically adopts a 40-mesh + 70-mesh aluminum water filter to obtain pure aluminum liquid.

4. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: the homogenization treatment in the step 2) is specifically as follows: soaking in a heating furnace at 490 deg.C for 8 hr, adjusting to 420 deg.C, and maintaining for 2 hr to treat the internal compound of the aluminum alloy matrix.

5. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: in the step 3), the initial rolling temperature of the hot rolling and rough rolling is 410-430 ℃, and the final rolling temperature of the hot rolling and finish rolling is controlled to be more than 360 ℃, so that the hot rolled coil has enough temperature to perform self annealing to complete recrystallization after the hot rolling is completed.

6. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: in the cold rolling procedure of the step 3), the single-pass reduction rate of the cold rolling is controlled to be 40%, and the intermediate annealing thickness is controlled according to the thickness and the state of the finished product, so that the cold rolling rate of the last pass is more than 60%.

7. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: and 3) in the step 3), the intermediate annealing temperature is 340-360 ℃, the temperature is kept for 4-6 h, and then the product is discharged out of the furnace to obtain a completely recrystallized structure and a part of dispersed and precipitated structure.

8. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: the finished product annealing specifically comprises the following steps: firstly, oil is removed at 210-240 ℃ for 3-5 h, and then the finished product is annealed at 260-290 ℃ for 4-6 h.

9. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: in the finished product structure after the finished product is annealed, at least 90% of intermetallic compound particles are less than 5 microns, less than 10% of intermetallic compound particles are 5-10 microns, less than 1% of intermetallic compound particles are 10-15 microns, and no particles larger than 15 microns are contained.

10. The method for manufacturing the automotive high-gloss aluminum alloy exterior trimming part plate according to claim 1, wherein the method comprises the following steps: in the anodic oxidation process, the temperature of the electrolytic cell does not exceed 35 ℃, and the thickness of the film layer is controlled to be 5-10 μm.

Technical Field

The invention belongs to the technical field of nonferrous metals, and particularly relates to a preparation method of a vehicle highlight aluminum alloy exterior trimming part plate.

Background

The automobile holding capacity is gradually increased, the updating and upgrading of the automobile are also gradually accelerated, and the market of medium and high-end automobiles is quietly rising under the condition that the current market is growing and weak. The middle-high end vehicle is mainly pleasing to consumers in performance and appearance, and along with the improvement of the appearance and the aesthetic feeling of the vehicle by the consumers, a large number of vehicle decorative parts are applied to the appearance of the vehicle to improve the aesthetic feeling of the appearance of the vehicle, such as vehicle window decorative strips, water cuts, top cover decorative strips, air inlet grilles, wheel trim decorative strips, door sill decorative strips, tail door decorative strips and the like. At present, highlight decorative strips for high-end vehicles have two derivatives, for example, high-end vehicles such as the Japanese system and the Korean system still adopt stainless steel materials, and European and American vehicles all adopt aluminum alloy materials. Since the beginning of the century, the high-gloss aluminum alloy decorative strip is widely applied to vehicles such as automobiles and trains in North America and developed countries such as Europe, and ten years ago, the aluminum alloy raw material enters the domestic market from the aluminum alloy origin places such as America, Sweden and the like through a trade means, and is rapidly applied to the fields of mirror surface oxidation and hardware decoration of domestic produced foreign vehicles, joint-procurement vehicles and high-end domestic vehicles. The 5505 aluminum alloy, 5005 aluminum alloy, 1070A aluminum alloy and the like which are commonly used for the mirror surface aluminum oxide alloy have the characteristics of high forming capability, good oxidation uniformity and high oxidation brightness, so far, the core technology and the product market of the mirror surface aluminum are monopolized by several multinational huge head companies such as Germany An aluminum, American aluminum, Kenjian (Switzerland) and the like, and the research and development and marketing aspects of the product in China are still in the initial groping stage.

At present, highlight decorative strips for medium-high end vehicles have two derivatives, for example, high-end vehicles such as the Japanese system and the Korean system still adopt stainless steel materials, and European and American vehicles all adopt aluminum alloy materials. The decorative strip made of stainless steel greatly increases the weight of the exterior trimming part undoubtedly, is not favorable for reducing the oil consumption of the traditional gasoline vehicle, and seriously influences the endurance mileage of the vehicle for the electric vehicle. In addition, due to the stainless steel material, the stainless steel has the defects of folds, cracks, fogging, whitening and the like easily in the bending and forming process, and the production cost is high due to the complex preparation process flow of the stainless steel decorative strip. In addition, the technology of the aluminum alloy of the European and American high-gloss decoration strip and the preparation process is not completely mastered by the domestic aluminum processing factory or the component company. The 5505 aluminum alloy is adopted to replace stainless steel, the aluminum alloy matrix with moderate strength and suitable for slight mechanical polishing is obtained by strictly controlling the chemical components, casting quality, hot rolling and cold rolling processing technology of the aluminum alloy for the decorative strip, and an oxide film layer with good quality is obtained by optimizing electrolytic polishing and anodic oxidation technology so as to achieve appearance beautification and use the decorative strip meeting the requirements. The automobile decoration prepared by the invention can meet the appearance requirement of high brightness, can also meet the requirement of certain strength to meet the goal of non-deformation in punch forming and subsequent use, has stronger advantages compared with the decoration adopting 1060 and 1070 low-strength aluminum alloy, and can also greatly reduce the purchase price of foreign aluminum alloy raw materials.

Disclosure of Invention

The invention aims to provide a vehicle highlight aluminum alloy exterior trimming part plate and a preparation method thereof aiming at the defects of the prior art, the vehicle trimming part is prepared by a method of component control, preparation process, oxidation process regulation and control and finished product structure control, in the whole process, the casting cooling, hot rolling process, cold rolling process and heat treatment process simultaneously realize structure homogenization control and surface homogenization control, the component homogenization and the structure homogenization can be realized to the maximum extent, and a solid foundation is laid for obtaining a good oxidation film layer and a highlight effect subsequently.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a vehicle highlight aluminum alloy exterior trimming part plate comprises the following steps of (1) casting a cast ingot; (2) homogenizing the cast ingot; (3) hot rolling; (4) cold rolling; (5) intermediate annealing; (6) cold rolling; (7) annealing the finished product; (8) cutting; (9) punching and forming; (10) mechanical polishing; (11) the anodic oxidation specifically comprises the following steps:

a: casting ingots: adding an aluminum ingot, an aluminum intermediate alloy ingot, a magnesium ingot and a manganese agent into a smelting furnace in proportion, melting, refining, deslagging and stirring, and then placing formed aluminum liquid into a standing furnace for standing; filtering the molten aluminum at 700 ℃, adding a grain refiner into the molten aluminum, refining by argon, and casting the refined molten aluminum into a flat aluminum alloy ingot by a semi-continuous casting method;

b: homogenizing cast ingots: sawing the head and the tail of the flat aluminum alloy cast ingot after heat preservation treatment, milling the surface, and then feeding the flat aluminum alloy cast ingot into a heating furnace for homogenization treatment;

c: firstly (3) hot rolling, then (4) cold rolling, (5) intermediate annealing, and finally (6) cold rolling again to obtain an aluminum alloy plate;

d: and (3) carrying out cleaning, oil removal, (7) finished product annealing, (8) cutting, (9) punch forming, (10) mechanical polishing and (11) anodic oxidation to obtain a strip, and stretching and straightening the strip on a stretch bending straightening machine to obtain a strip with better plate shape, thus obtaining the automotive highlight aluminum alloy exterior trimming part plate.

The automotive high-gloss aluminum alloy exterior trimming part plate comprises, by mass, 0.02-0.05% of Si (Si is easy to combine with Fe to form a compound, the content of Si is controlled so as to obtain a smaller amount of compound, and the situation that the glossiness of an oxide film is influenced more by the content of AlFeSi in the oxide film after oxidation) 0.01-0.04% (Fe element is usually impurity in an industrial pure aluminum ingot, the lower the content is better, the content of 0.04% is controlled so as to obtain a smaller amount of compound, the glossiness of the oxide film is prevented from being influenced more by the content of AlFeSi in the oxide film after oxidation, meanwhile, a certain Fe content is beneficial to grain refinement in the hot processing process of the aluminum ingot), 0.002-0.005% of Cu, 0-0.002% of Mn, and 0.6-1.0% of Mg (Mg is a solid solution phase, the matrix strength is improved, the content of 1% is controlled so as to obtain a smaller AlMg phase, and the situation that the phase of AlMg is aggregated so as to cause uneven structure or stripe defects, meanwhile, the higher the Mg content is, the higher the homogenization temperature is, the higher the requirement is), 0-0.008% of Cr, 0-0.006% of Zn and 0.01-0.03% of Ti (Ti is a refiner, a certain addition amount is required to be ensured, the refinement of ingot casting grains is ensured, and especially the secondary surface grains and the surface grains of the ingot casting cannot generate coarse grains, otherwise the coarse grains are inherited to a hot rolling structure and a cold rolling structure, and are finally displayed in the form of oxidation stripes. ) The other single impurity is not more than 0.01 percent, and the balance is Al.

In the casting process of (1) the ingot, the thickness of the slab is controlled to be 400-450mm by adopting a small-specification crystallizer, so that heat can be uniformly dissipated outwards along the periphery in the cooling process, and the phenomenon that the surface metal structure of the ingot is not uniform and stripe defects occur due to chilling caused by nonuniform heat conduction is prevented, and the defect structure is easily inherited to a finished plate and even to the subsequent oxidation surface.

In the casting process of the cast ingot, the molten aluminum filter plays an important role in the cleanliness of the cast ingot, and a relatively pure aluminum alloy cast ingot can be obtained by adopting 40-mesh + 70-mesh double filtration; meanwhile, the internal compound of the aluminum alloy matrix is treated by adopting a homogenization system of 490 ℃/8h to convert the internal compound into a compound with smaller size, thereby laying a good aluminum matrix for subsequent anodic oxidation.

In the hot rolling procedure (3), the initial rolling temperature of the hot rolling rough rolling is 410-430 ℃, high hot rolling temperature is easy to cause aluminum adhesion, the surface quality is affected, and the lower initial rolling temperature can cause insufficient thermoplasticity of the aluminum alloy slab ingot. In addition, the temperature of the finish rolling of the hot finish rolling is controlled to be more than 360 ℃ so as to ensure that the hot rolled coil has enough temperature to carry out self-annealing to complete recrystallization after the hot rolling is completed, and the cooling mode adopts natural cooling for 2 hours and then adopts strong wind to cool the coil to be less than 160 ℃, so that the completely recrystallized cubic texture can account for more than 80 percent to balance the deformation texture in the subsequent cold rolling process. The balance of the cubic texture and the deformation texture is the key to solve the stripe defect.

In addition, it should be noted that the oxide film with high gloss and no stripe defect is closely related to the aluminum alloy matrix structure, and is more closely related to the aluminum alloy preparation process, and the optimization of each process from casting, rolling to heat treatment has a certain influence on the quality of the oxide film, but the influence of only a single process is not obvious.

In the cold rolling procedures of (4) and (6), the single-pass reduction rate of the cold rolling is controlled to be 40%, fewer cold rolling passes are adopted as far as possible, and the intermediate annealing thickness is controlled according to the thickness and the state of the finished product, so that the cold rolling rate of the last pass is more than 60% to obtain enough cold deformation energy storage for subsequent annealing of the finished product.

In the cold rolling processes (4) and (6), the mechanical properties of the sheet are improved mainly to obtain more deformation structures, but the deformation of the sheet must be uniformly distributed on the surface and the core of the sheet, and is in a balanced distribution state with the existing cubic texture in the sheet.

And (5) controlling the temperature of the intermediate annealing material to be 340-360 ℃, keeping the temperature for 4-6 h, and discharging to obtain a completely recrystallized structure and a part of dispersed and precipitated structure.

And (3) deoiling at the furnace gas temperature of 210-240 ℃/3-5H in the finished product annealing in the step (7), then annealing the finished product at the metal temperature of 260-290 ℃/4-6H, and regulating and controlling the mechanical properties of the material to obtain different states such as H22, H24 and the like.

In the finished structure, at least 90% of the intermetallic compound particles have a size less than 5 μm, less than 10% of the intermetallic compound particles have a size in the range of 5-10 μm, less than 1% of the intermetallic compound particles have a size in the range of 10-15 μm, and no particles larger than 15 μm are present. The matrix structure can be well adapted to the surface layer for anodic oxidation coating, thereby obtaining an oxidation film layer with compact structure and good quality. The excellent finished product structure is the decisive condition for obtaining the high light oxidation film.

In the polishing process (10), besides mechanical polishing for removing necessary corner burrs generated by stamping forming, electrolytic polishing for improving the surface state is also carried out, the roughness of the surface layer of the part is ensured to be less than 0.02 mu m, and the requirement of a substrate for bright oxidation is met.

In the (11) anodic oxidation process, the temperature of the oxidation tank is controlled carefully to ensure that the temperature of the electrolytic tank does not exceed 35 ℃, the oxide film is ensured to generate a compact structure film layer at a lower temperature, the film layer thickness is controlled to be optimal within 5-10 mu m, the temperature of the oxide film tank is higher, the structure of the oxide film is loose, and meanwhile, the glossiness of the oxide film is reduced when the thickness of the oxide film is larger.

Has the advantages that: the preparation process of the automotive high-gloss aluminum alloy exterior trimming part plate can reduce the weight of an automobile and avoid surface defects in a stainless steel forming process, the aluminum alloy plate has compact and uniform matrix structure, the product achieves high brightness after being anodized, and has no light and shade alternative stripe defects, thereby meeting the requirements of customers on color brightness and solving the technical problems of material strength and surface quality in the prior art.

Drawings

FIG. 1 is a grain structure diagram of various rolling passes of ingots of different thicknesses; in the figure, 1,2,3,4 and 5 are different rolling passes, the left side is a plate structure with the slab thickness of 520mm, and the right side is a plate structure with the slab thickness of 420 mm; as can be seen from the figure, the smaller the slab ingot thickness is, the more the stripe defect is improved;

FIG. 2 is a graph showing distribution of compounds in anodized aluminum alloy strip treated at different homogenization temperatures; the left graph shows the 460 ℃ homogenization temperature; the right panel shows the homogenization temperature at 490 ℃; as can be seen from the figure, the aluminum alloy which adopts the double filtering of 40 meshes +70 meshes and the high-temperature homogenization treatment becomes purer, and the brightness 580-620Gu after the anodic oxidation is much higher than the brightness 520-560Gu on the left side;

FIG. 3 is a comparison graph of the cubic texture content at different finishing temperatures; the cubic texture accounting for 85 percent of the left-side finish rolling temperature of 380 ℃ is the preferred texture for obtaining the oxide film with high brightness and no stripe defects; the right-side finishing temperature is 330 ℃, and the cubic texture accounts for 63 percent and is easy to generate stripe defects;

FIG. 4 is a comparison graph of the surface topography of the oxide film under different finished product tissues; the left side adopts a small-size flat ingot, the high temperature homogenization is carried out, and an aluminum alloy plate obtained at a high finishing temperature obtains an oxide film which is high in brightness, smooth and free of appearance defects after anodic oxidation; the right side adopts a large-size flat ingot, the surface of the aluminum alloy oxide film is uneven at low-temperature homogenization and low finishing temperature, and the stripe defect exists.

Detailed Description

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.

Example 1

The automotive highlight aluminum alloy exterior trim plate comprises, by mass, 0.04% of Si, 0.03% of Fe, 0.005% of Cu, 0.002% of Mn, 0.8% of Mg, 0.005% of Cr, 0.004% of Zn, 0.01% of Ti, no more than 0.01% of other single impurities, and the balance of Al.

The preparation method of the automotive high-gloss aluminum alloy exterior trimming part plate comprises the following steps:

1) adding an aluminum ingot, an aluminum intermediate alloy ingot, a magnesium ingot and a manganese agent into a smelting furnace in proportion, melting, refining, deslagging and stirring at 730 ℃, then, stirring at the speed of 80r/min, and placing the formed aluminum liquid into a standing furnace for standing for 2.0 h;

2) at the temperature of 700 ℃, after the aluminum liquid passes through a 40-mesh + 70-mesh double-stage filtering device, adding a grain refiner, wherein the refiner is Al-5Ti-0.2B, and the addition amount of the grain refiner is 60-120 ppm. After argon refining, casting the refined molten aluminum into a flat aluminum alloy ingot by a semi-continuous casting method, wherein the specification of the flat ingot is 400mm in thickness;

3) and sawing the head and the tail of the flat aluminum alloy ingot after heat preservation treatment, and milling the surface, wherein the milling amount is 22 mm/surface, and the thickness of the ingot after milling is 356 mm. Uniformly heating in a heating furnace at 490 ℃ for 8h, adjusting to 420 ℃ and keeping the temperature for 2h, and then discharging from the furnace for hot rolling;

4) rolling the ingot blank discharged from the furnace into a hot rolled strip with the thickness of 6.4mm by a hot rolling mill, controlling the reduction rate of the final 3 times of hot rough rolling to be more than or equal to 50%, controlling the reduction rate of each time of hot finish rolling to be less than or equal to 35%, and controlling the finish rolling temperature of a finish rolling mill to be 360 ℃ (the specific reduction rate is shown in the following table);

5) and air cooling the hot-rolled coil for 2 hours, and cooling the hot-rolled coil to below 160 ℃ by adopting strong wind.

6) Cold rolling a 6.4mm hot rolled coil to 1.5mm, and controlling the reduction rate of a single pass to be about 40%;

7) adopting an intermediate annealing treatment system of 350 ℃/4h for a cold-rolled coil with the diameter of 1.5 mm;

8) the 1.5mm cold rolled coil was again cold rolled to a finished thickness of 1.2mm to obtain a sheet in the H22 temper.

9) And (3) carrying out stretch straightening on the strip obtained after cleaning, oil removing, finished product annealing, cutting, punch forming, mechanical polishing and anodic oxidation on the strip on a stretch bending straightening machine to obtain the strip with better plate shape, namely the automotive high-gloss aluminum alloy exterior trimming part plate, wherein the tensile strength is 115-135MPa, the yield strength is 70-90MPa, and the elongation is 16-20%.

The finished product is annealed at the furnace gas temperature of 220 ℃/4h for oil removal and then at the metal temperature of 280 ℃/5h for finished product annealing;

the finished product structure after the annealing of the finished product has at least 90 percent of intermetallic compound particles with the size less than 5 mu m, less than 10 percent of intermetallic compound particles with the size between 5 and 10 mu m, less than 1 percent of intermetallic compound particles with the size between 10 and 15 mu m and no particles with the size more than 15 mu m.

In the anodic oxidation process, the temperature of the electrolytic cell does not exceed 35 ℃, the oxide film is ensured to generate a compact structure film layer at a lower temperature, and the thickness of the film layer is controlled to be 5-10 mu m.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.