Aluminum alloy plate, processing method of aluminum alloy plate, part comprising aluminum alloy plate and automobile

Abstract

The invention relates to an aluminum alloy plate, a machining method thereof, a part comprising the aluminum alloy plate and an automobile. The processing method comprises the following steps: i) subjecting an aluminum ingot and an intermediate alloy to smelting and electromagnetic stirring together; ii) supplementing materials, wherein an aluminum-titanium intermediate alloy is added, so that titanium accounts for not more than 0.15 wt% of the total weight of the melt; iii) refining, turning down and standing; iv) discharging, online crystal refinement, degassing and filtering slag removal are carried out, and online crystal refinement is carried out through an aluminum-titanium-boron alloy, so that titanium accounts for 0.07-0.15 wt% of the total weight of the melt; v) carrying out cast rolling under the intervention of a pulse current field to obtain a cast-rolled plate; and vi) carrying out hot rolling to obtain the aluminum alloy plate. According to the aluminum alloy machining method, the segregation problem is effectively eliminated, and therefore the aluminum alloy plate with the good mechanical property is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of metal product processing, and specifically relates to an aluminum alloy plate, a processing method thereof, and parts and automobiles comprising the same. Background Art

[0002] Aluminum alloys are widely used due to their high performance to weight ratio, favorable corrosion resistance and other factors.

[0003] For example, in order to improve the range and safety performance of electric vehicles, major automakers are increasingly using aluminum alloys.

[0004] The aluminum alloys that have been used in the automotive industry mainly include 2xxx (Al-Cu-Mg), 5xxx (Al-Mg), 6xxx (Al-Mg-Si) and 7xxx (Al-Zn-Mg-Cu) series. Among them, the 5xxx series aluminum alloy has excellent formability, the heat-treatable and strengthened 2xxx series aluminum alloy has high strength and good weldability and forgeability, the 6xxx series aluminum alloy has both good formability in T4 / T4P state and high paint aging hardening response ability (the increment of alloy yield strength before and after paint), and the 7xxx series aluminum alloy has good strength and toughness.

[0005] High-strength aluminum alloys are widely used in aerospace, automobile manufacturing and other fields due to their excellent mechanical properties and corrosion resistance.

[0006] High-strength aluminum alloys are prone to central segregation during the casting and rolling process. This is because the alloying elements of high-strength aluminum alloys are easy to diffuse at high temperatures, resulting in central segregation during the casting and rolling process, that is, the alloying elements are enriched in the central part of the aluminum alloy plate, resulting in a large difference in performance between the central part and the edge of the plate.

[0007] High-strength aluminum alloys are prone to band breakage and cracks during the cold rolling process. This is due to the existence of center segregation. In the subsequent cold rolling process, band breakage and cracks are prone to occur, resulting in a decrease in the quality of the aluminum alloy sheet, especially a decrease in mechanical properties.

[0008] Therefore, there is a need in the art for an improved aluminum alloy processing method that can effectively eliminate the segregation problem occurring during the casting and rolling process, thereby obtaining an aluminum alloy with good mechanical properties. Summary of the invention

[0009] The purpose of the present invention is to provide an improved aluminum alloy processing method, which can effectively eliminate the segregation problem occurring during the casting and rolling process, thereby obtaining an aluminum alloy with good mechanical properties.

[0010] According to a first aspect of the present invention, there is provided an aluminum alloy processing method, characterized in that it comprises the following steps: i) subjecting the aluminum ingot and the master alloy to melting and electromagnetic stirring; ii) performing a feed, wherein an aluminum-titanium master alloy is added so that titanium accounts for no more than 0.15% by weight of the total weight of the melt; iii) refining, pouring and standing; iv) performing discharge, online crystal refinement, degassing, filtering and deslagging, wherein online crystal refinement is performed by aluminum-titanium-boron alloy so that titanium accounts for 0.07-0.15% by weight of the total weight of the melt; v) performing casting and rolling under the intervention of a pulsed current field to obtain a cast-rolled plate; and vi) hot rolling to obtain an aluminum alloy plate.

[0011] According to a second aspect of the present invention, there is provided an aluminum alloy plate, characterized in that it is prepared by the above processing method.

[0012] According to a third aspect of the present invention, there is provided an aluminum alloy component, characterized in that it is processed from the above-mentioned aluminum alloy sheet.

[0013] According to a fourth aspect of the present invention, there is provided an automobile, characterized in that it comprises the above-mentioned aluminum alloy component.

[0014] The aluminum alloy processing method of the present invention effectively eliminates the segregation problem, thereby obtaining an aluminum alloy plate with good mechanical properties. The aluminum alloy prepared by the aluminum alloy processing method of the present invention has a tensile strength of up to 230 MPa, a yield strength of up to 190 MPa, and an elongation of up to 21%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention is described in conjunction with the accompanying drawings so that those skilled in the art can better understand the various features and advantages of the present invention, wherein: Figure 1 The metallographic structure of the cast sheet after the casting and rolling in Example 1 is shown.

[0016] Figure 2 The metallographic structure of the plate after hot rolling in Example 1 is shown. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is described in detail below.

[0018] According to a first aspect of the present invention, there is provided an aluminum alloy processing method, characterized in that it comprises the following steps: i) subjecting the aluminum ingot and the master alloy to melting and electromagnetic stirring; ii) performing a feed, wherein an aluminum-titanium master alloy is added so that titanium accounts for no more than 0.15% by weight of the total weight of the melt; iii) refining, pouring and standing; iv) performing discharge, online crystal refinement, degassing, filtering and deslagging, wherein online crystal refinement is performed by aluminum-titanium-boron alloy so that titanium accounts for 0.07-0.15% by weight of the total weight of the melt; v) performing casting and rolling under the intervention of a pulsed current field to obtain a cast-rolled plate; and vi) hot rolling to obtain an aluminum alloy plate.

[0019] The cast-rolled plate obtained by the cast-rolling method of the present invention may be any aluminum alloy material commonly used for automobile parts processing, such as an aluminum alloy material selected from 2xxx, 6xxx and 7xxx series.

[0020] Those skilled in the art can select the intermediate alloy in i) according to the composition requirements of the aluminum alloy cast plate. For example, an aluminum-magnesium alloy is used so that the final aluminum alloy cast plate contains magnesium.

[0021] Specifically, smelting includes melting the raw materials, sampling and testing the alloy composition, and adding different components as needed according to the alloy composition table for blending.

[0022] Smelting may be carried out in a smelting furnace at a temperature in the range of, for example, 720-780°C, preferably in the range of 740-760°C.

[0023] The electromagnetic stirring can be performed in multiple times, for example, in 2-3 times, each time for 5-10 minutes.

[0024] In the feeding process, other master alloys besides the aluminum-titanium master alloy can be added according to the need of composition adjustment.

[0025] In some embodiments, after the composition is adjusted through the feeding process, the mass percentage of each component in the aluminum alloy melt is: Fe≤0.5%, Mg 0.25-0.6%, Si 1.0-1.5%, Cu≤0.2%, Zn≤0.2%, Mn≤0.2%, Ti≤0.15%, Cr≤0.10%, and the balance is Al.

[0026] Refining can be carried out at a temperature in the range of, for example, 730-770°C, preferably 740-750°C.

[0027] Refining can be carried out for example for 30-60 min.

[0028] Refining can be carried out in 2-3 times.

[0029] Preferably, pouring is carried out at a melt temperature of 730-760°C.

[0030] Preferably, the mixture is placed in a heat preservation furnace at 720-750°C.

[0031] The discharge can be carried out using the process parameters commonly used in the art.

[0032] By adding grain refiners (i.e., aluminum-titanium-boron alloy), it is possible to both refine the grains and reduce the macro-segregation of the ingot while avoiding increasing costs and causing new segregation.

[0033] Preferably, the grain refiner (ie, aluminum-titanium-boron alloy) is added in an amount such that the titanium content reaches 0.09-0.12 wt%.

[0034] Preferably, the degassing is performed at 720-750°C. More preferably, the degassing is performed at 730-740°C.

[0035] Preferably, the degassing medium is argon.

[0036] Preferably, the peak current is in the range of 100-300A.

[0037] Preferably, the pulse frequency is in the range of 30-100 Hz.

[0038] Preferably, the pulse duty cycle is in the range of 10-20%.

[0039] Preferably, the opening of the casting nozzle used for casting and rolling is 8-20 mm, preferably 10-18 mm, and the length of the casting and rolling zone is not less than 65 mm, preferably 70-90 mm.

[0040] Preferably, the casting speed is in the range of 300-1100 mm / min, more preferably in the range of 400-700 mm / min.

[0041] The inventors found that the generation of cracks was reduced by reducing the casting speed.

[0042] The cast plate may have a suitable thickness, for example, 8-12 mm.

[0043] Preferably, hot rolling is performed with preheating of the cast plate.

[0044] Preferably, the hot rolling is performed at a temperature not lower than 300°C to ensure that the deformation of the hot-rolled billet is within the range of 30-70%. For example, the hot rolling can be performed at a temperature within the range of 300-400°C.

[0045] During the hot rolling process, heating may be performed to ensure that the hot rolling is performed at a suitable temperature.

[0046] Preferably, the hot rolling speed is synchronized with the casting speed.

[0047] Preferably, the tension is controlled at 0.2-0.4 Kg / mm 2 within the range.

[0048] Preferably, the rollers are lubricated by carbon coating using liquefied gas combustion.

[0049] Preferably, the maximum rolling force during hot rolling does not exceed 3000 T.

[0050] The hot-rolled plate may have a suitable thickness, for example, 2-7 mm.

[0051] The inventors found that hot rolling can refine the size of the precipitation phase in the center of the plate and strip to make it evenly distributed, while also refining the grain size and improving the ductility.

[0052] The aluminum alloy processing method of the present invention can effectively eliminate the segregation problem occurring during the casting and rolling process, thereby obtaining an aluminum alloy with good mechanical properties.

[0053] The aluminum alloy plate obtained by the processing method of the present invention has good mechanical properties, for example, the tensile strength can reach 230 MPa, the yield strength can reach 190 MPa, and the elongation can reach 21%.

[0054] According to a second aspect of the present invention, there is provided an aluminum alloy plate, characterized in that it is prepared by the above processing method.

[0055] According to a third aspect of the present invention, there is provided an aluminum alloy component, characterized in that it is processed from the above-mentioned aluminum alloy sheet.

[0056] The components may be structural parts such as B-pillar inner panels, B-pillar inner panel reinforcement plates, A-pillar inner panels, hinge reinforcement plates, floor beams, door inner panels, front and rear cover inner panels, floor skins, battery box cover panels and bottom guard panels, etc. According to a fourth aspect of the present invention, there is provided an automobile, characterized in that it comprises the above-mentioned aluminum alloy component.

[0057] In the present specification and claims, the nomenclature of aluminum alloys complies with the latest regulations of the Aluminum Association (The Aluminum Association) known in the art. And each alloy in each series has been registered with the Aluminum Association this year. For example, the aluminum alloys in the 2xxx series are called high-strength alloys and usually contain magnesium and copper as the main alloying elements. The alloys in the 6xxx and 7xxx series are also called high-strength alloys and are usually strengthened by heat treatment via precipitation of their main alloying elements, which are silicon and magnesium for the 6xxx series and copper, zinc and magnesium for the 7xxx series.

[0058] The terms “comprising” and “including” described in the present application encompass a case where the component is further comprised or includes other elements not explicitly mentioned as well as a case where the component is composed of the mentioned elements.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention belongs. When the definition of a term in this specification conflicts with the meaning commonly understood by those skilled in the art to which the invention belongs, the definition described in this article shall prevail.

[0060] Unless otherwise indicated, all numerical values ​​expressing amounts of ingredients, temperature, and so forth used in the specification and claims are to be understood as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that can vary depending upon the desired properties desired to be obtained. Example

[0061] The following will further illustrate the concept of the present invention and the technical effects produced in conjunction with the embodiments, so that those skilled in the art can fully understand the purpose, characteristics and effects of the present invention. It is not difficult for those skilled in the art to understand that the embodiments herein are only for illustrative purposes, and the scope of the present invention is not limited thereto. If not clearly stated, the raw materials used in the embodiments are those commonly used in the art.

[0062] Example 1 Follow the steps below to process aluminum alloy sheets: Melting and electromagnetic stirring: pure aluminum ingots and master alloys are added into the melting furnace, heated and melted into a melt. The melting process is carried out by electromagnetic stirring twice, each time for 8 minutes.

[0063] Replenish material to adjust the composition: take samples from the melt to quickly test the chemical composition, and then replenish material. During the replenishing process, add aluminum-titanium master alloy to adjust the alloy composition to meet Fe≤0.5%, Mg 0.25-0.6%, Si 1.0-1.5%, Cu≤0.2%, Zn≤0.2%, Mn≤0.2%, Ti≤0.15%, Cr≤0.10%, and the balance is Al.

[0064] Refining, pouring, and standing: After the sampling test is qualified, it is refined twice at a temperature of 740-750℃, each time for 20 minutes. After refining, it is left to stand for 10 minutes to remove slag to ensure that there is no residue on the surface. The furnace is poured at a melt temperature of 740-750℃ and it is left to stand in a holding furnace at 730-740℃.

[0065] Vertical plate discharge, Al-Ti-B wire online addition, degassing, filtration: Vertical plate slag running speed: 1200-1500mm / min, slag running time: 8min.

[0066] Al-Ti-B wire is added in the flow channel before the degassing box. The addition of Al-Ti-B is not allowed to stop or be interrupted. The addition amount is based on the total weight of the aluminum alloy, so that the total Ti element content reaches 0.07-0.15%.

[0067] The degassing was carried out stably at 730-740°C, the rotor speed was 500r / min, and the degassing medium was argon.

[0068] The filter box uses 30 mesh and 50 mesh double-stage filter plates.

[0069] Casting and rolling: The opening of the casting nozzle is 14mm, the length of the casting and rolling zone is 80mm, the thickness of the nozzle is 2-3mm, and the upper and lower nozzles are staggered 6mm. The roller crown is 0.15mm, the cooling water temperature in the roller is 30-35℃, the casting and rolling speed is 400-700mm / min, and the melt in front of the casting and rolling roller is added with a pulse current field, the peak current is 200A, the pulse frequency is 50Hz, and the pulse duty cycle is 10%-20%. Casting and rolling are carried out to obtain a cast-rolled plate with a thickness of 10mm.

[0070] Hot rolling: hot rolling is carried out using the residual heat of the cast billet itself. When the temperature during hot rolling is lower than 300°C, induction heating is used to ensure that the temperature of the billet is within the range of 300-400°C when entering the hot rolling mill. The rolling speed is synchronized with the casting and rolling, and the tension is controlled at 0.2-0.4 Kg / mm 2 The rollers are lubricated by liquefied gas combustion carbon coating, the hot rolling mill uses 800mm diameter rollers, the roller surface width is 2000mm, the maximum rolling force is 3000T, and the plate thickness after hot rolling is 5mm.

[0071] Figure 1 The metallographic structure of the cast sheet after casting and rolling is shown.

[0072] from Figure 1 It can be seen that the quality of the cast-rolled structure is good, there is no obvious segregation, all of them are fine equiaxed crystal structures, and no coarse precipitate phase appears.

[0073] Figure 2 The metallographic structure of the plate after hot rolling is shown.

[0074] from Figure 2 and Figure 1 It can be seen from the comparison that hot rolling can refine the size of the precipitated phase in the plate and strip, make its distribution uniform, and refine the grain size at the same time.

[0075] The tensile strength, yield strength and elongation of the hot rolled strip samples were tested three times according to ASTM E8 / E8M, and the results are listed in Table 1.

[0076] Table 1 It can be seen from Table 1 that the cast-rolled plate obtained by the method of the present invention has good mechanical properties such as tensile strength and elongation, with an average tensile strength of 233 MPa, an average yield strength of 193.3 MPa, and an average elongation of 22.2%.

[0077] Although some aspects of the present invention have been shown and discussed, it will be appreciated by those skilled in the art that changes may be made to the above aspects without departing from the principles and spirit of the invention, and the scope of the invention shall be defined by the claims and their equivalents.

Claims

1. A method for processing aluminum alloy, characterized in that: Including the following processes: i) subjecting the aluminum ingot and the master alloy to melting and electromagnetic stirring; ii) performing a feed, wherein an aluminum-titanium master alloy is added so that titanium accounts for no more than 0.15% by weight of the total weight of the melt; iii) refining, pouring and standing; iv) performing discharge, online crystal refinement, degassing, filtering and deslagging, wherein online crystal refinement is performed by aluminum-titanium-boron alloy so that titanium accounts for 0.07-0.15% by weight of the total weight of the melt; v) performing casting and rolling under the intervention of a pulsed current field to obtain a cast-rolled plate; and vi) hot rolling to obtain an aluminum alloy plate.

2. The method according to claim 1, characterized in that The peak current is in the range of 100-300A.

3. The method according to claim 1 or 2, characterized in that: The pulse frequency is in the range of 30-100 Hz.

4. The method according to claim 1 or 2, characterized in that: The pulse duty cycle is in the range of 10-20%.

5. The method according to claim 1 or 2, characterized in that: Hot rolling is performed at a temperature not lower than 300°C.

6. The method according to claim 1 or 2, characterized in that: The tension is controlled at 0.2-0.4 Kg / mm 2 within the range.

7. The method according to claim 1 or 2, characterized in that: The maximum rolling force during hot rolling does not exceed 3000T.

8. The method according to claim 1 or 2, characterized in that: The obtained aluminum alloy cast-rolled plate is a 6xxx series aluminum alloy material.

9. An aluminum alloy plate, characterized in that: Prepared by the processing method according to any one of claims 1 to 8.

10. An aluminum alloy component, characterized in that: It is processed from the aluminum alloy sheet according to claim 9.

11. A car, characterized in that: Comprising the aluminum alloy component according to claim 10.

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