Aluminum alloy cast-rolled plate, cast-rolling method of aluminum alloy cast-rolled plate, and part and automobile comprising aluminum alloy cast-rolled plate

Abstract

The invention relates to an aluminum alloy cast-rolled plate, a cast-rolling method thereof, a part comprising the aluminum alloy cast-rolled plate and an automobile. The cast-rolling method comprises the following steps: i) smelting, electromagnetically stirring and slagging off a waste aluminum material, a pure aluminum material and an intermediate alloy together, wherein the waste aluminum material accounts for at least 50 wt% of the total amount of the waste aluminum material and the pure aluminum material; ii) supplementing materials, wherein an aluminum-titanium intermediate alloy is added, so that titanium accounts for 0.03-0.07 wt% of the total weight of the melt; iii) refining, turning down and standing; and iv) the cast-rolled plate is obtained after discharging, online crystal refinement, degassing, filtering slag removal and cast rolling are conducted, online crystal refinement is conducted through the aluminum-titanium-boron alloy, and titanium accounts for 0.07-0.15 wt% of the total weight of the cast-rolled plate. According to the aluminum alloy cast rolling method, the segregation problem caused by the high scrap aluminum ratio is effectively eliminated, and therefore the cast rolling plate which can be rolled into a thin plate is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of metal product processing, and specifically relates to an aluminum alloy cast-rolled plate, a casting and rolling method thereof, and parts and automobiles containing 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] The scrapping of aluminum alloy parts has led to the existence of a large amount of aluminum alloy waste. In the casting and rolling process of aluminum alloy materials, as the proportion of recycled aluminum continues to increase, the conventional casting and rolling process of high-strength aluminum alloys such as 6xxx series is prone to serious segregation defects in products due to the increase in the types and contents of alloy elements. In addition, due to the increase in alloy elements, the strength of aluminum alloys increases, which increases the difficulty of casting and rolling and subsequent cold rolling of thin plates.

[0007] Therefore, there is a need in the art for an improved aluminum alloy casting method that can effectively eliminate the segregation problem caused by a high scrap aluminum ratio, thereby obtaining a cast plate that can be rolled into a thin plate. Summary of the invention

[0008] The object of the present invention is to provide an improved aluminum alloy casting and rolling method, which can effectively eliminate the segregation problem caused by a high scrap aluminum ratio, thereby obtaining a cast-rolled plate that can be rolled into a thin plate.

[0009] According to a first aspect of the present invention, there is provided an aluminum alloy casting and rolling method, characterized in that it comprises the following steps:

[0010] i) subjecting scrap aluminum, pure aluminum and master alloy to smelting, electromagnetic stirring and slagging, wherein the scrap aluminum accounts for at least 50 weight percent of the total weight of the scrap aluminum and the pure aluminum;

[0011] ii) performing a feed, wherein an aluminum-titanium master alloy is added so that titanium accounts for 0.03-0.07 weight % of the total weight of the melt;

[0012] iii) refining, pouring and resting; and

[0013] iv) performing discharge, online crystal refinement, degassing, filtering and deslagging, and casting and rolling to obtain a cast plate, wherein online crystal refinement is performed by aluminum-titanium-boron alloy so that titanium accounts for 0.07-0.15 weight % of the total weight of the cast plate.

[0014] According to a second aspect of the present invention, there is provided an aluminum alloy cast-rolled plate, characterized in that it is prepared by the above-mentioned casting and rolling method.

[0015] 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 cast and rolled plate.

[0016] 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.

[0017] The aluminum alloy casting and rolling method of the present invention effectively eliminates the segregation problem caused by the high scrap aluminum ratio, thereby obtaining a cast-rolled plate that can be rolled into a thin plate. The cast-rolled plate prepared by the aluminum alloy casting and rolling method of the present invention has a hardness of up to 88HV, a tensile strength of up to 205Mpa, a yield strength of up to 165MPa, and an elongation of up to 19%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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:

[0019] Figure 1 The metallographic structure of the cast-rolled plate after the casting process in Example 1 is shown, wherein, in the thickness direction, a represents the upper surface, b represents the central core, and c represents the lower surface. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described in detail below.

[0021] According to a first aspect of the present invention, there is provided an aluminum alloy casting and rolling method, characterized in that it comprises the following steps:

[0022] i) subjecting scrap aluminum, pure aluminum and master alloy to smelting, electromagnetic stirring and slagging, wherein the scrap aluminum accounts for at least 50 weight percent of the total weight of the scrap aluminum and the pure aluminum;

[0023] ii) performing a feed, wherein an aluminum-titanium master alloy is added so that titanium accounts for 0.03-0.07 weight % of the total weight of the melt;

[0024] iii) refining, pouring and resting; and

[0025] iv) performing discharge, online crystal refinement, degassing, filtering and deslagging, and casting and rolling to obtain a cast plate, wherein online crystal refinement is performed by aluminum-titanium-boron alloy so that titanium accounts for 0.07-0.15 weight % of the total weight of the cast plate.

[0026] The cast 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 aluminum alloy materials selected from 2xxx, 6xxx and 7xxx series, especially 6xxx series aluminum alloy materials.

[0027] 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.

[0028] 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.

[0029] In some embodiments, the scrap aluminum material comprises at least 60 wt%, at least 70 wt%, or at least 80 wt%, such as 60-90 wt% or 85-90 wt%, of the total amount of scrap aluminum material and pure aluminum material.

[0030] The scrap aluminum material may be one or more of grade 1 scrap aluminum, grade 2 scrap aluminum and recycled scrap aluminum.

[0031] As described in the present application, grade 1 aluminum scrap refers to casting scrap with the same grade as the aluminum alloy to be cast or lower alloying elements or cold-rolled scrap with a thickness of less than 1.4 mm.

[0032] As described in the present application, Grade 2 aluminum scrap refers to scrap coils of plates, strips, and foils, cold-rolled trimming scraps, or performance test sample scraps with the same grade as the aluminum alloy to be cast or with lower alloying elements and a thickness of 0.01-1.4.

[0033] As described in the present application, recycled scrap aluminum refers to aluminum chips, oil-contaminated scrap aluminum, aluminum foil packaging blocks, various mechanical processing wastes, aluminum ash, etc.

[0034] In some embodiments, the scrap aluminum material contains one or more alloying elements of iron, copper, zinc, magnesium, manganese, and silicon, and in particular, the total amount thereof exceeds the maximum addition amount in the aluminum alloy grade to be cast and rolled.

[0035] Smelting may be carried out in a smelting furnace at a temperature in the range of, for example, 710-780°C, preferably in the range of 720-740°C.

[0036] The electromagnetic stirring can be performed in multiple times, for example, in 2-3 times, each time for 5-8 minutes.

[0037] The deslagging agent used in the deslagging is a deslagging agent commonly used in the art.

[0038] In the feeding process, other master alloys besides the aluminum-titanium master alloy can be added according to the need of composition adjustment.

[0039] In some embodiments, after the composition is adjusted through the feeding process, the mass percentage of each component in the aluminum alloy melt is: Si 1.0-1.5%, Mg 0.3-0.8%, Fe 0.3-0.35%, Cu<0.25%, Mn<0.2%, Cr<0.15%, Zn<0.2%, Ti 0.03-0.07%, and the balance is Al.

[0040] Refining can be carried out at a temperature in the range of, for example, 730-770°C, preferably 740-750°C.

[0041] Refining may be carried out for example for 20-30 min.

[0042] Preferably, slagging is performed after refining and before pouring the furnace to ensure that there is no residue on the surface.

[0043] The deslagging agent used in the deslagging is a deslagging agent commonly used in the art.

[0044] Preferably, pouring is carried out at a melt temperature of 740-750°C.

[0045] The discharge can be carried out using the process parameters commonly used in the art.

[0046] 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.

[0047] Preferably, the grain refiner (ie, aluminum-titanium-boron alloy) is added in an amount such that the titanium content reaches 0.07-0.1 wt %.

[0048] Preferably, the degassing is carried out at 730-740°C.

[0049] Preferably, the degassing medium is argon.

[0050] Preferably, the casting rolls used for casting are lubricated with graphite emulsion.

[0051] Preferably, the diameter of the casting roll used for casting is not less than 900 mm, for example, in the range of 900-1500 mm, and the rolling force is not less than 20000 KN, for example, in the range of 20000-40000 KN.

[0052] Preferably, the opening of the casting nozzle used for casting and rolling is 12-22 mm, preferably 13-20 mm, and the length of the casting and rolling zone is not less than 65 mm, preferably 70-90 mm.

[0053] The inventors have found that by increasing the nozzle opening and the length of the casting zone, the residence time of the molten metal in the casting zone can be increased, the solidification rate of the molten metal can be increased, and the quality of the cast billet can be improved, especially segregation can be reduced.

[0054] Preferably, the casting speed is in the range of 300-1100 mm / min, more preferably in the range of 400-700 mm / min.

[0055] The inventors found that the generation of cracks was reduced by reducing the casting speed.

[0056] The aluminum alloy cast rolled plate may have a suitable thickness, for example, 3-8 mm.

[0057] The aluminum alloy casting and rolling method of the present invention can fully utilize the waste aluminum materials while effectively eliminating the segregation problem occurring during the casting and rolling process with a high waste aluminum ratio.

[0058] The aluminum alloy cast plate obtained by the casting and rolling method of the present invention has good mechanical properties, such as hardness up to 88HV, tensile strength up to 205Mpa, yield strength up to 165MPa, and elongation up to 19%, meeting the requirements of the next step of thin plate production.

[0059] According to a second aspect of the present invention, there is provided an aluminum alloy cast-rolled plate, characterized in that it is prepared by the above-mentioned casting and rolling method.

[0060] 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 cast and rolled plate.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Example

[0068] 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.

[0069] Example 1

[0070] Follow the steps below to process cast and rolled plates:

[0071] Melting, electromagnetic stirring, and slag removal: Add waste aluminum materials, pure aluminum ingots, and master alloys into a melting furnace, heat and melt them into a melt, and use electromagnetic stirring for 3 times, each time for 6 minutes, until the temperature reaches 720-740°C. Add a slag remover, stir evenly, and let stand for 8 minutes, then remove the slag. The waste accounts for 85% by weight of the total amount of waste materials and pure aluminum ingots, of which grade 1 waste aluminum accounts for 40% by weight, grade 2 waste aluminum accounts for 30% by weight, and recycled waste aluminum (aluminum chips) accounts for 15% by weight.

[0072] Replenishing material to adjust the composition: taking samples from the melt to quickly detect the chemical composition, and then replenishing the material. During the replenishing process, aluminum-titanium master alloy is added to adjust the alloy composition mass ratio to: Si 1.0-1.5%, Mg 0.3-0.8%, Fe 0.3-0.35%, Cu <0.25%, Mn <0.2%, Cr <0.15%, Zn <0.2%, Ti 0.03-0.05%, and the balance is Al.

[0073] Refining, pouring, and standing: After the sampling test is qualified, it is refined at a temperature of 740-750℃ for 25 minutes. After refining, it is stood for 8 minutes, and then the slag is removed to ensure that there is no residue on the surface. The furnace is poured at a melt temperature of 740-745℃, and it is stood in a holding furnace at 730-735℃.

[0074] Vertical plate discharge, Al-5Ti-1B wire online addition, degassing, filtration, casting and rolling:

[0075] The temperature of the box before the vertical plate discharge is 740-750 degrees Celsius, the slag running speed is 1300-1500mm / min, the slag running time is 5min, the casting nozzle opening is 16mm, the casting and rolling zone length is 75mm, the nozzle thickness is 2-3mm, and the upper and lower nozzles are staggered 6mm front and back.

[0076] Al-5Ti-1B wire is added in the flow channel before the degassing box. The addition of Al-5Ti-1B is not allowed to be stuck or interrupted. The swing of Al-5Ti-1B is required to be 30-50 times / minute. The addition amount is based on the total weight of the aluminum alloy, so that the total Ti element content reaches 0.07-0.1%.

[0077] The degassing was carried out stably at 730-740°C, the rotor speed was 500r / min, and the degassing medium was argon.

[0078] The filter box uses 30 mesh and 50 mesh double-stage filter plates. When the vertical plates are normal, the melt temperature of the front box is 700-720℃.

[0079] The diameter of the casting and rolling roll is 1200mm, the roll crown is 0.15mm, the cooling water temperature inside the roll is 30-35℃, the surface is sprayed with lubricating graphite emulsion, the rolling force is 30000KN, the casting and rolling speed is 600mm / min, and then the cast and rolled strip is obtained by shearing and coiling, and the strip thickness is 5mm.

[0080] Figure 1 The metallographic structure of the cast sheet after the casting process is shown.

[0081] from Figure 1 It can be seen that the grain size of the upper and lower surfaces and the middle part of the sheet is level 1, the sheet surface quality is good, there is no obvious segregation, the sheet strip structure is a fine equiaxed crystal structure, and there is no coarse precipitate phase in the structure.

[0082] The hardness, tensile strength, yield strength and elongation of the cast plate samples were tested three times according to ASTM E8 / E8M. The results are listed in Table 1.

[0083] Table 1. Properties of the cast plate obtained

[0084]

[0085] As can be seen from Table 1, the tensile strength and elongation of the cast plate obtained by the method of the present invention are good, with an average hardness of 90HV, an average tensile strength of 208Mpa, an average yield strength of 166.3MPa, and an average elongation of 20.6%, meeting the requirements for the next step of thin plate production.

[0086] 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 casting and rolling an aluminum alloy, characterized in that: Including the following processes: i) subjecting waste aluminum, pure aluminum and master alloy to smelting, electromagnetic stirring and slagging together, wherein the waste aluminum accounts for at least 50 weight percent of the total weight of the waste aluminum and the pure aluminum; ii) performing a feed, wherein an aluminum-titanium master alloy is added so that titanium accounts for 0.03-0.07 weight % of the total weight of the melt; iii) refining, pouring and resting; and iv) performing discharge, online crystal refinement, degassing, filtering and deslagging, and casting and rolling to obtain a cast plate, wherein online crystal refinement is performed by aluminum-titanium-boron alloy so that titanium accounts for 0.07-0.15 weight % of the total weight of the cast plate.

2. The method according to claim 1, characterized in that: The scrap aluminum material accounts for 60-90 weight % of the total amount of the scrap aluminum material and the pure aluminum material.

3. The method according to claim 1, characterized in that The scrap aluminum material contains one or more alloy elements of iron, copper, zinc, magnesium, manganese and silicon.

4. The method according to claim 1 or 2, characterized in that: The diameter of the casting roll used for casting and rolling shall not be less than 900mm, and the rolling force shall not be less than 20000KN.

5. The method according to claim 1 or 2, characterized in that: The opening of the casting nozzle used for casting and rolling is 12-22mm, and the length of the casting and rolling zone is not less than 65mm.

6. The method according to claim 1 or 2, characterized in that: The casting speed is in the range of 300-1100 mm / min.

7. 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.

8. An aluminum alloy cast-rolled plate, characterized in that: The method is prepared by the casting and rolling method according to any one of claims 1 to 7.

9. An aluminum alloy component, characterized in that: It is processed from the aluminum alloy cast-rolled plate according to claim 8.

10. An automobile, characterized in that: Comprising the aluminum alloy component according to claim 9.

Images