Aluminum alloy drawn material

Abstract

To provide an aluminum alloy sheet material that can be blended with various types of aluminum scraps at a high recycling rate and has excellent mechanical properties such as elongation and strength. 【Solution means】The aluminum alloy sheet material has an aluminum alloy part. The aluminum alloy part contains, in mass% based on the total mass of the aluminum alloy part, Si: 1.0% or more and 7.5% or less, Fe: 0.15% or more and 0.8% or less, and Mn: 0.3% or more and 1.0% or less, and Cu: 0.5% or less, Mg: 2.0% or less, Zn: 0.7% or less, and the balance consists of Al and unavoidable impurities. When the contents of Si and Mg in the total mass of the aluminum alloy part are [Si] and [Mg] in mass% respectively, the value α calculated by the formula (1): α = [Si] - 2×[Mg] is 0 or more, and the value β calculated by the formula (2): β = [Si] + 2.25×[Mg] is 7.5 or less, and the average crystal grain size is 40 μm or more and 350 μm or less.

Description

Technical Field

[0001] The present invention relates to an aluminum alloy rolled material.

Background Art

[0002] In recent years, achieving carbon neutrality has become an issue for society as a whole, and various methods for solving the above problems have been studied. For example, from the perspective of resource depletion, recycling of various materials has progressed, and recycling of metals that are consumed in large quantities has been carried out for a long time. For example, aluminum consumes a large amount of electricity during the production of new ingots and emits CO 2 . Therefore, by reducing the amount of new ingots used through recycling, the CO 2 emissions during the production of aluminum alloy materials can be significantly reduced. However, due to the influence of impurities in the scraps used for recycling, there are various problems in applying recycling to rolled materials compared to casting materials. Patent Document 1 proposes a method for producing an aluminum alloy for automotive members, in which aluminum alloy casting scraps are added with sash scraps, aluminum can scraps (UBC: Used Beverage Can), or ingots, melted to dilute impurities, and component adjustment is performed as necessary.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even when using the manufacturing method described in Patent Document 1 above, it is necessary to set the Si content in the alloy after component adjustment to, for example, 4.85% by mass or less. In addition, when the usage rate of casting part scraps or automotive casting scraps is increased, the elongation and bendability of the obtained aluminum alloy material are significantly reduced.

[0005] The present invention has been made in view of such problems, and is an aluminum alloy sheet that can be manufactured with a high recycling rate using various types of aluminum alloy scraps, and has excellent mechanical properties such as elongation and strength, and particularly has a high formability. The purpose is to provide an aluminum alloy sheet.

Means for Solving the Problems

[0006] The above object of the present invention is achieved by the following configuration [1] related to the following aluminum alloy sheet.

[0007] [1] An aluminum alloy sheet having an aluminum alloy part, The aluminum alloy part, with respect to the total mass of the aluminum alloy part, Si: 1.0% by mass or more and 7.5% by mass or less, Fe: 0.15% by mass or more and 0.8% by mass or less, and Mn: 0.3% by mass or more and 1.0% by mass or less, contains Cu: 0.5% by mass or less, Mg: 2.0% by mass or less, Zn: 0.7% by mass or less, and the balance consists of Al and unavoidable impurities, When the content of Si with respect to the total mass of the aluminum alloy part is [Si] in mass%, and the content of Mg with respect to the total mass of the aluminum alloy part is [Mg] in mass%, the value α calculated by the following formula (1) is 0 or more, and the value β calculated by the following formula (2) is 7.5 or less, The average crystal grain size in the aluminum alloy part is 40 μm or more and 350 μm or less, and is characterized by an aluminum alloy sheet. Formula (1): α = [Si] - 2 × [Mg] Formula (2): β = [Si] + 2.25 × [Mg]

[0008] In addition, preferred embodiments of the present invention related to the aluminum alloy sheet relate to the following [2] and [3].

[0009] [2] The aluminum alloy rolled material according to [1], wherein the average crystal grain size in the aluminum alloy part is 250 μm or less.

[0010] [3] The aluminum alloy rolled material according to [1] or [2], wherein the average crystal grain size in the aluminum alloy part is 60 μm or more. [Advantages of the Invention]

[0011] According to the present invention, it is possible to blend various types of aluminum scraps at a high recycling rate, and the aluminum alloy rolled material has excellent mechanical properties such as elongation and strength, and particularly has high formability. [Embodiments for Carrying Out the Invention]

[0012] It is expected that aluminum alloy scraps will become difficult to obtain from the market due to the expanding demand in the future. Therefore, the inventors of the present application have intensively studied an aluminum alloy rolled material that can be blended with various alloy scraps without being limited to specific alloy scraps. In addition, the contents of Si and Mg and their ratios have a great influence on the formability of aluminum alloy materials. Therefore, the inventors of the present application have found the optimal range of the average crystal grain size in the aluminum alloy part and the optimal range of the formula representing the balance between the Si content and the Mg content.

[0013] Hereinafter, the aluminum alloy rolled material and its manufacturing method according to the embodiment of the present invention will be described. In this specification, the "aluminum alloy rolled material" may be simply referred to as the "rolled material".

[0014] [Aluminum Alloy Rolled Material] The aluminum alloy rolled material according to the present embodiment has an aluminum alloy part having the following alloy composition. Hereinafter, the chemical components contained in the aluminum alloy part in the aluminum alloy rolled material and the reasons for limiting their contents will be described in detail.

[0015] <Aluminum alloy part> (Si: 1.0 mass% or more and 7.5 mass% or less) Si is an element that easily forms Si compounds and Si grains of a size that can serve as recrystallization nuclei. On the other hand, when the Si content becomes excessive, the Si compounds and Si grains are more likely to coarsen, leading to a decrease in elongation and a reduction in formability. Note that Si is an element contained in various aluminum alloy scraps. In this embodiment, since the value calculated by a specific formula using the Si content and the average crystal grain size are defined within an appropriate range, even with a high recycling rate, mechanical properties such as elongation and strength are good, and the formability of the aluminum alloy part can be improved.

[0016] When the Si content in the aluminum alloy part is less than 1.0 mass%, the average crystal grain size becomes coarse due to a shortage of recrystallization nuclei. Also, when the Si content in the aluminum alloy part is less than 1.0 mass%, it is necessary to reduce the usage amount of aluminum alloy scraps with a high Si content, and the recycling rate cannot be improved. Therefore, the Si content in the aluminum alloy part is 1.0 mass% or more based on the total mass of the aluminum alloy part, preferably 1.5 mass% or more, and more preferably 2.0 mass% or more. On the other hand, when the Si content in the aluminum alloy part exceeds 7.5 mass%, large Si compounds and Si grains are likely to be formed, leading to a decrease in elongation and a reduction in formability. Therefore, the Si content in the aluminum alloy part is 7.5 mass% or less based on the total mass of the aluminum alloy part, preferably 6.0 mass% or less, and more preferably 5.0 mass% or less.

[0017] (Fe: 0.15 mass% or more and 0.8 mass% or less) Fe is an element that easily forms intermetallic compounds of a size that can serve as recrystallization nuclei. Therefore, when the Fe content is less than 0.15% by mass, the average crystal grain size becomes coarse due to a shortage of recrystallization nuclei. Also, since Fe is generally contained in aluminum alloy scraps, in order to make the Fe content in the aluminum alloy part less than 0.15% by mass, it is necessary to use high-purity aluminum ingots, which increases the manufacturing cost. Therefore, the Fe content in the aluminum alloy part is preferably 0.15% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.25% by mass or more with respect to the total mass of the aluminum alloy part. On the other hand, when the Fe content in the aluminum alloy part exceeds 0.8% by mass, large intermetallic compounds are likely to be formed during casting, leading to a decrease in elongation and a deterioration in formability. Therefore, the Fe content in the aluminum alloy part is preferably 0.8% by mass or less, more preferably 0.75% by mass or less, and even more preferably 0.7% by mass or less with respect to the total mass of the aluminum alloy part.

[0018] (Mn: 0.3% by mass or more and 1.0% by mass or less) Mn is an element that has the effect of improving the strength of the aluminum alloy part. When the Mn content in the aluminum alloy part is less than 0.3% by mass, the effect of improving the strength cannot be sufficiently obtained. Therefore, the Mn content with respect to the total mass of the aluminum alloy part is 0.3% by mass or more, preferably 0.4% by mass or more, and more preferably 0.5% by mass or more. On the other hand, when the Mn content in the aluminum alloy part exceeds 1.0% by mass, large intermetallic compounds are likely to be formed during casting, leading to a decrease in elongation and a deterioration in formability. Therefore, the Mn content in the aluminum alloy part is preferably 1.0% by mass or less, more preferably 0.95% by mass or less, and even more preferably 0.9% by mass or less with respect to the total mass of the aluminum alloy part.

[0019] (Cu: 0.5% by mass or less) Cu is an element that affects the strength and formability of the drawn material. Although Cu is generally contained in aluminum alloy scraps, in this embodiment, the Cu content in the aluminum alloy part may be 0% by mass. However, when Cu is contained in the aluminum alloy part for the purpose of improving strength, the Cu content in the aluminum alloy part is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, based on the total mass of the aluminum alloy part. On the other hand, when the Cu content in the aluminum alloy part exceeds 0.5% by mass, the elongation decreases, leading to a decrease in formability. Therefore, the Cu content in the aluminum alloy part is 0.5% by mass or less, preferably 0.45% by mass or less, more preferably 0.4% by mass or less, based on the total mass of the aluminum alloy part.

[0020] (Mg: 2.0% by mass or less) Mg is an element that affects the strength and formability of the drawn material. In this embodiment, the Mg content in the aluminum alloy part may be 0% by mass. However, when Mg is contained in the aluminum alloy part for the purpose of improving strength, the Mg content in the aluminum alloy part is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, based on the total mass of the aluminum alloy part. On the other hand, when the Mg content in the aluminum alloy part exceeds 2.0% by mass, large Mg compounds are likely to be formed, resulting in a decrease in elongation and a decrease in formability. Therefore, the Mg content in the aluminum alloy part is 2.0% by mass or less, preferably 1.5% by mass or less, more preferably 1.0% by mass or less, based on the total mass of the aluminum alloy part.

[0021] (Zn: 0.7% by mass or less) In this embodiment, the Zn content in the aluminum alloy part may be 0% by mass. However, since Zn is generally contained in aluminum alloy scraps, the Zn content in the aluminum alloy part is considered to be 0.1% by mass or more based on the total mass of the aluminum alloy part. On the other hand, when the Zn content in the aluminum alloy part exceeds 0.7% by mass, MgZn 2An increase in precipitates such as these may lead to a decrease in elongation, which may result in a decrease in formability. Further, when the Zn content in the aluminum alloy part exceeds 0.7% by mass, the pitting potential becomes lower and the corrosion rate increases. Therefore, the Zn content in the aluminum alloy part is preferably 0.7% by mass or less, more preferably 0.65% by mass or less, and even more preferably 0.6% by mass or less with respect to the total mass of the aluminum alloy part.

[0022] (Other elements) In the aluminum alloy sheet according to the present embodiment, the total of Al, Si, Fe, Mn, Cu, Mg, and Zn in the aluminum alloy part is preferably 98.5% by mass or more, more preferably 99% by mass or more, and even more preferably 99.5% by mass or more with respect to the total mass of the aluminum alloy part. In addition, examples of other elements of the above elements include Cr, Zr, Ni, Sn, Sr, Sb, and Ca. Since these elements may be contained in the aluminum alloy scraps, they may also be contained in the aluminum alloy part obtained using these alloy scraps. In the present embodiment, the contents of Cr, Zr, Ni, Sn, Pb, Sr, Sb, and Ca in the aluminum alloy part are not particularly limited. For example, the Cr content is preferably 0.1% by mass or less, the Zr content is preferably 0.1% by mass or less, the Ni content is preferably 0.2% by mass or less, the Sn content is preferably 0.1% by mass or less, the Sr content is preferably 0.18% by mass or less, the Sb content is preferably 0.5% by mass or less, and the Ca content is preferably 0.1% by mass or less.

[0023] (Balance: Al and unavoidable impurities) The remainder of the aluminum alloy part in the aluminum alloy rolled material according to this embodiment consists of Al and inevitable impurities. Examples of the inevitable impurities include Na and the like. Note that the Na content in the aluminum alloy part is preferably 0.002 mass% or less with respect to the total mass of the aluminum alloy part. Further, the Al content in the aluminum alloy part is preferably 80 mass% or more with respect to the total mass of the aluminum alloy part, and the total amount of the inevitable impurities in the aluminum alloy part is preferably 0.15 mass% or less with respect to the total mass of the aluminum alloy part.

[0024] Next, an equation using the Si content and the Mg content in the aluminum alloy part, and the crystal grain size will be described.

[0025] (Value α calculated by Equation (1): 0 or more) If the Mg content increases too much with respect to the Si content, the strength increases due to the influence of solid solution strengthening or precipitation effect, and the elongation decreases. In this embodiment, the influence of the Si content and the Mg content on the formability is represented by the following equation (1). That is, when the value α calculated by the following equation (1) becomes a value smaller than 0, the elongation decreases and the formability of the aluminum alloy part deteriorates. Therefore, the above value α is 0 or more, preferably 0.5 or more, and more preferably 0.75 or more.

[0026] Equation (1): α = [Si] - 2×[Mg]

[0027] (Value β calculated by Equation (2): 7.5 or less) When both the Si content and the Mg content become high values, the precipitation of large Mg 2 Si precipitates increases, and the elongation decreases due to the influence of the precipitates. In this embodiment, the influence exerted by the precipitates is represented by the following equation (2). That is, when the value β calculated by the following equation (2) exceeds 7.5, the elongation of the aluminum alloy part decreases. Therefore, the above value β is 7.5 or less, preferably 7.0 or less, and more preferably 6.5 or less.

[0028] Formula (2): β = [Si] + 2.25 × [Mg]

[0029] However, in the above formulas (1) and (2), [Si] is the value representing the content of Si in terms of mass% with respect to the total mass of the aluminum alloy part, and [Mg] is the value representing the content of Mg in terms of mass% with respect to the total mass of the aluminum alloy part.

[0030] (Average crystal grain size) When the average crystal grain size of the aluminum alloy part exceeds 350 μm, strain tends to concentrate during deformation and elongation decreases. Therefore, the average crystal grain size of the aluminum alloy part is 350 μm or less, preferably 330 μm or less, more preferably 300 μm or less, and particularly preferably 250 μm or less. On the other hand, when the average crystal grain size is less than 40 μm, the work hardening ability decreases, so strain tends to concentrate at the grain boundaries and elongation decreases. Therefore, the average crystal grain size of the aluminum alloy part is 40 μm or more, preferably 60 μm or more, and more preferably 75 μm or more.

[0031] ><Manufacturing method of aluminum alloy part> The manufacturing method of the aluminum alloy part in this embodiment will be specifically described below.

[0032] The manufacturing method of the aluminum alloy part in this embodiment includes, for example, a step of casting an aluminum alloy having the above chemical composition, a step of homogenization heat treatment, a step of hot rolling, a step of cold rolling, and a step of annealing.

[0033] Furthermore, each step will be described in detail. [Melting, casting] An ingot of a predetermined shape is produced from the molten metal obtained by melting an aluminum alloy having the above chemical composition. The method for melting and casting the aluminum alloy is not particularly limited, and a conventional method or a known method may be used.

[0034] [Homogenization heat treatment] Next, the cast aluminum alloy ingot is subjected to homogenization heat treatment. The conditions for the homogenization heat treatment are such that a compound serving as a recrystallization nucleus is sufficiently generated, and the temperature is such that the average crystal grain size of the aluminum alloy part is within an appropriate range. For example, it is preferably 450°C to 620°C, more preferably 470°C to 600°C, and even more preferably 480°C to 580°C.

[0035] [Hot rolling] Hot rolling is performed on the aluminum alloy material after the homogenization heat treatment. The starting temperature and the ending temperature of the hot rolling are such that a compound serving as a recrystallization nucleus is sufficiently generated, and the temperature is such that the average crystal grain size of the aluminum alloy part is within an appropriate range. For example, the starting temperature is preferably 440°C to 610°C, and the ending temperature is preferably 230°C to 400°C. More preferably, the starting temperature is 470°C to 570°C, and the ending temperature is 250°C to 370°C.

[0036] [Cold rolling] Cold rolling is performed on the aluminum alloy material after the hot rolling. The rolling reduction during the cold rolling is not particularly limited, but for example, it is preferably 50% or more and 98% or less. The strain applied during the cold rolling is set to a rolling reduction such that the average crystal grain size is within an appropriate range in order to promote recrystallization during the final annealing. For example, it is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more.

[0037] [Final annealing] Final annealing treatment is performed on the aluminum alloy plate subjected to the above cold rolling. If the temperature of the final annealing treatment at this time is less than 280°C, recrystallization is not sufficient, so the elongation decreases. Therefore, the final annealing temperature is preferably 280°C or higher, more preferably 290°C or higher, and even more preferably 300°C or higher. On the other hand, when the final annealing temperature is 330°C or lower, the average crystal grain size can be easily adjusted to the desired range, and the elongation can be improved. Therefore, the final annealing temperature is preferably 330°C or lower, more preferably 320°C or lower. The holding time at the final annealing temperature is not particularly limited and can be, for example, 1 hour or more and 5 hours or less. Further, the cooling rate after the final annealing is not particularly limited. Furthermore, the final annealing treatment may be performed in a batch annealing furnace or a continuous annealing furnace, but it is preferable to use a continuous annealing furnace.

[0038] Note that the aluminum alloy part in the present embodiment can be manufactured with a high recycling rate from various aluminum alloy scraps, and the content of each component and the average crystal grain size are adjusted so that excellent mechanical properties can be obtained. The recycling rate is a value expressed as a percentage of the mass of the used aluminum alloy scraps with respect to the total mass of the obtained aluminum alloy part. If the recycling rate is 50% or more, an aluminum alloy part can be obtained using a sufficient amount of aluminum alloy scraps, and a reduction in manufacturing cost and a reduction in CO 2 emissions can be sufficiently achieved. Therefore, a high recycling rate is preferably 50% or more, more preferably 60% or more, still more preferably 75% or more, and particularly preferably 90% or more.

[0039] A part of the aluminum alloy drawn material according to the present embodiment may be constituted by an aluminum alloy part, or all of the aluminum alloy drawn material may be constituted by an aluminum alloy part. An example in which a part of the aluminum alloy drawn material is constituted by an aluminum alloy part will be described.

[0040] The aluminum alloy drawn material according to the present embodiment may be composed of a clad material having a core material and a skin material laminated on at least a part of the surface of the core material. Examples of the skin material include sacrificial anode materials. Hereinafter, the components contained in the sacrificial anode material, which is an example of the core material and the skin material contained in the aluminum alloy drawn material, and the reasons for limiting their contents will be described below.

[0041] <Core material> The core material is made of the above aluminum alloy part. Therefore, the reasons for limiting each component contained in the core material and its content are as described in the explanation of the above aluminum alloy part.

[0042] <Sacrificial anode material> (Zn: 0.50 mass% or more and 6.00 mass% or less) Zn in the sacrificial anode material is an element that has the effect of lowering the potential of the base material and enhancing the sacrificial corrosion prevention effect on the core material, thereby preventing pitting corrosion and crevice corrosion. If the Zn content in the sacrificial anode material is 0.50 mass% or more, a sufficient sacrificial corrosion prevention effect can be obtained. Therefore, the Zn content in the sacrificial anode material is preferably 0.50 mass% or more, more preferably 0.60 mass% or more, and even more preferably 0.70 mass% or more based on the total mass of the sacrificial anode material. Also, when the Zn content in the sacrificial anode material is 6.00 mass% or less, it is possible to prevent the self-corrosion of the sacrificial anode material from increasing too much and suppress the decrease in the corrosion resistance of the aluminum alloy rolled material. Therefore, the Zn content in the sacrificial anode material is preferably 6.00 mass% or less, more preferably 5.70 mass% or less, and even more preferably 5.50 mass% or less based on the total mass of the sacrificial anode material.

[0043] (Si: 0.05 mass% or more and 1.50 mass% or less) Si in the sacrificial anode material is an element that has the effect of improving the strength of the sacrificial anode material. If the Si content in the sacrificial anode material is 0.05 mass% or more, the effect of improving the strength can be obtained. Therefore, the Si content in the sacrificial anode material is preferably 0.05 mass% or more, more preferably 0.10 mass% or more, and even more preferably 0.15 mass% or more based on the total mass of the sacrificial anode material. Also, when the Si content in the sacrificial anode material is 1.50 mass% or less, it is possible to prevent the formation of large Si compounds and Si grains and suppress the decrease in formability. Therefore, the Si content in the sacrificial anode material is preferably 1.50 mass% or less, more preferably 1.45 mass% or less, and even more preferably 1.40 mass% or less based on the total mass of the sacrificial anode material.

[0044] (Fe: 0.05 mass% or more and 2.00 mass% or less) Fe in the sacrificial anode material is an element that forms Al-Fe-Mn-Si-based compounds together with Si and Mn and has the effect of improving strength by dispersion strengthening. If the Fe content in the sacrificial anode material is 0.05 mass% or more, the effect of improving strength can be obtained. Therefore, the Fe content in the sacrificial anode material is preferably 0.05 mass% or more, more preferably 0.10 mass% or more, and even more preferably 0.12 mass% or more based on the total mass of the sacrificial anode material. Also, when the Fe content in the sacrificial anode material is 2.00 mass% or less, the formation of large intermetallic compounds during casting can be prevented, and a decrease in plastic workability can be suppressed. Therefore, the Fe content in the sacrificial anode material is preferably 2.00 mass% or less, more preferably 1.80 mass% or less, and even more preferably 1.60 mass% or less based on the total mass of the sacrificial anode material.

[0045] (Mg: 3.00 mass% or less) Mg in the sacrificial anode material is an element that improves the strength of the sacrificial anode material itself by precipitating Mg 2 Si. However, in this embodiment, the Mg content in the sacrificial anode material may be 0 mass%. Also, when the Mg content in the sacrificial anode material is 3.00 mass% or less, it can be easily crimped during hot clad rolling. Therefore, the Mg content in the sacrificial anode material is preferably 3.00 mass% or less, more preferably 2.80 mass% or less, and even more preferably 2.60 mass% or less based on the total mass of the sacrificial anode material.

[0046] (Mn: 1.80 mass% or less) Mn in the sacrificial anode material is an element that has the effect of improving strength by dissolving in the base material or forming an Al-Mn-Si-based intermetallic compound together with Si. However, in the present embodiment, the Mn content in the sacrificial anode material may be 0% by mass. Also, when the Mn content in the sacrificial anode material is 1.80% by mass or less, the formation of large intermetallic compounds during casting can be prevented, and a decrease in formability can be suppressed. Therefore, the Mn content in the sacrificial anode material is preferably 1.80% by mass or less, more preferably 1.60% by mass or less, and even more preferably 1.40% by mass or less with respect to the total mass of the sacrificial anode material.

[0047] (Cu: 0.50% by mass or less) When the Cu content in the sacrificial anode material is 0.50% by mass or less, the pitting potential of the sacrificial anode material can be prevented from nobilizing, and the effect of sacrificial corrosion can be sufficiently obtained. Therefore, the Cu content in the sacrificial anode material is preferably 0.50% by mass or less, more preferably 0.40% by mass or less, and even more preferably 0.30% by mass or less with respect to the total mass of the sacrificial anode material.

[0048] (Cr: 0.30% by mass or less) Cr in the sacrificial anode material is an element that has the effect of improving strength by solid solution strengthening. However, in the present embodiment, the Cr content in the sacrificial anode material may be 0% by mass. Also, when the Cr content in the sacrificial anode material is 0.30% by mass or less, the formation of large intermetallic compounds during casting can be prevented, and a decrease in plastic workability can be suppressed. Therefore, the Cr content in the sacrificial anode material is preferably 0.30% by mass or less, more preferably 0.20% by mass or less, and even more preferably 0.10% by mass or less with respect to the total mass of the sacrificial anode material.

[0049] (Ti: 0.30% by mass or less) Ti in the sacrificial anode material is an element that has the effect of improving strength through solid solution strengthening. However, in this embodiment, the Ti content in the sacrificial anode material may be 0% by mass. Also, when the Ti content in the sacrificial anode material is 0.30% by mass or less, it is possible to prevent the formation of large intermetallic compounds during casting and suppress the decrease in plastic workability. Therefore, the Ti content in the sacrificial anode material is preferably 0.30% by mass or less, more preferably 0.20% by mass or less, and even more preferably 0.10% by mass or less with respect to the total mass of the sacrificial anode material.

[0050] (Zr: 0.30% by mass or less) Zr in the sacrificial anode material is an element that has the effect of improving strength through solid solution strengthening. However, in this embodiment, the Zr content in the sacrificial anode material may be 0% by mass. Also, when the Zr content in the sacrificial anode material is 0.30% by mass or less, it is possible to prevent the formation of large intermetallic compounds during casting and suppress the decrease in plastic workability. Therefore, the Zr content in the sacrificial anode material is preferably 0.30% by mass or less, more preferably 0.20% by mass or less, and even more preferably 0.10% by mass or less with respect to the total mass of the sacrificial anode material.

[0051] (V: 0.30% by mass or less) V in the sacrificial anode material is an element that has the effect of improving strength through solid solution strengthening. However, in this embodiment, the V content in the sacrificial anode material may be 0% by mass. Also, when the V content in the sacrificial anode material is 0.30% by mass or less, it is possible to prevent the formation of large intermetallic compounds during casting and suppress the decrease in plastic workability. Therefore, the V content in the sacrificial anode material is preferably 0.30% by mass or less, more preferably 0.20% by mass or less, and even more preferably 0.10% by mass or less with respect to the total mass of the sacrificial anode material.

[0052] (Balance: Al and unavoidable impurities) The remainder of the sacrificial anode material contained in the aluminum alloy strip is Al and inevitable impurities. The inevitable impurities include Ca, Be, Sb, rare earth elements, Li, etc. Specifically, they may be contained in the range of Ca: 0.05% by mass or less, Be: 0.01% by mass or less, and other elements: less than 0.01% by mass. Also, the total amount of inevitable impurities in the sacrificial anode material is preferably 0.05% by mass or less based on the total mass of the sacrificial anode material.

[0053] <Form of the aluminum alloy strip> In this embodiment, the form of the aluminum alloy strip is not particularly limited. As described above, it may be a plate-shaped aluminum alloy strip composed only of the aluminum alloy part, or it may be in a form in which a plate-shaped core material and a plate-shaped skin material are laminated. When laminated, the skin material may be laminated only on a part of the surface of the core material, or may be laminated on the entire surface of one or both sides. Also, it may be a clad material obtained by extrusion. For example, the skin material may be laminated on at least one of the inner and outer surfaces of a hollow extruded material, or on the outer surface of a solid extruded material.

Examples

[0054] Examples are given below to more specifically explain this embodiment. However, the present invention is not limited to these examples, and modifications can be made and implemented within the range that conforms to the gist of the present invention, and all of them are included in the technical scope of the present invention.

[0055] <Manufacture of the aluminum alloy strip> The aluminum alloy raw material was melted at a temperature of 730°C. Then, by casting this at a temperature of 700°C, an ingot for the core material with a thickness of 50 mm, a width of 145 mm, and a length of 250 mm was produced. Also, an ingot for the sacrificial anode material containing 0.15% by mass of Si, 0.25% by mass of Fe, and 1.0% by mass of Zn was manufactured.

[0056] Next, the obtained ingots for the core material and the sacrificial anode material were subjected to a homogenization heat treatment at an appropriate temperature in the range of 480°C to 540°C for 4 hours to obtain a homogenized material for the core material and a homogenized material for the sacrificial anode material. Although the appropriate soaking temperature varies depending on the components, in this example, the soaking temperature was set to a temperature 70°C to 150°C lower than the solidus temperature. Then, the homogenized material for the sacrificial anode material was rolled and laminated on one surface of the homogenized material for the core material to produce a clad material for rolling. At that time, it was calculated and laminated so that the clad ratio of the sacrificial anode material was 17%. In the hot rolling process, the clad material for rolling with a thickness of 50 mm, a width of 145 mm, and a length of 100 mm was hot rolled until the thickness became 2.5 mm and the length became about 1.8 m. The starting temperature of the hot rolling was set to an appropriate temperature in the range of 470°C to 530°C. Although the appropriate starting temperature of the hot rolling varies depending on the components, in this example, the starting temperature of the hot rolling was set to a temperature 80°C to 160°C lower than the solidus temperature. Also, the finishing temperature of the hot rolling was set to an appropriate temperature in the range of 280°C to 320°C. Regarding the appropriate finishing temperature of the hot rolling, it also varies depending on the components, but the finishing temperature of the hot rolling was set to a temperature 0°C to 30°C higher than the recrystallization temperature.

[0057] Thereafter, cold rolling was performed on the aluminum alloy plate that had been hot rolled. In the cold rolling process, the aluminum alloy plate after hot rolling with a thickness of 2.5 mm and a length of about 1.8 m was cold rolled until the thickness became 0.15 mm. Then, the aluminum alloy plate that had been cold rolled was subjected to a final annealing treatment in a continuous annealing furnace. The temperature of this final annealing treatment was set to an appropriate temperature in the range of 300°C to 320°C and held for 1 hour to 5 hours. Although the appropriate final annealing temperature varies depending on the components, the final annealing temperature was set to a temperature 10°C to 30°C higher than the recrystallization temperature. As a result, a rolled material (aluminum alloy expanded material) of the above size in which the core material made of an aluminum alloy part and the sacrificial anode material are laminated was obtained.

[0058] The contents of each component in the obtained aluminum alloy sheet, the values obtained by the formula, the average crystal grain size, and the evaluation results of the tensile strength and elongation are shown in Tables 1 and 2 below. Note that the balance of each component of the aluminum alloy sheet shown in Table 1 is Al and inevitable impurities.

[0059] <Evaluation of Aluminum Alloy Sheet> (Evaluation of Mechanical Properties) In accordance with the "Tensile Test Method for Metallic Materials" of JIS Z 2241:2023, test piece No. 13B described in Appendix B was taken from the obtained aluminum alloy sheet, and a tensile test was carried out in the range of 10 to 35 °C to measure the tensile strength and elongation after fracture. As the evaluation criteria, those with a tensile strength of 120 MPa or more and an elongation of 14% or more were judged to have good mechanical properties. Since a high formability can be obtained when the aluminum alloy sheet has excellent elongation, specifically, when the elongation is 14% or more, it can be judged that the formability is particularly excellent.

[0060] In this example, a multi-layer rolled material in which a core material made of an aluminum alloy part and a sacrificial anode material are laminated is produced, and the mechanical properties are judged according to the above evaluation criteria. However, even a single plate made only of the aluminum alloy part can be judged according to the above criteria. This is because, in terms of strength, the single plate tends to be improved compared to the multi-layer rolled material. Also, in terms of elongation, although the single plate tends to be lower than the multi-layer rolled material, since the thickness of the sacrificial anode material is extremely thin at 30 μm or less compared to the thickness of the multi-layer rolled material, it is considered that the elongation will not decrease even in the case of a single plate.

[0061] (Measurement of Average Crystal Grain Size) The obtained aluminum alloy sheet was cut into 2 cm squares to collect test pieces for measuring the average crystal grain size. After polishing the surface parallel to the rolling direction of the aluminum alloy sheet in this test piece, the microstructure was observed with a microscope. The average crystal grain size on the surface parallel to the rolling direction of the core material was measured at two locations each by the concentric circle method, and the average value was obtained.

[0062]

Table 1

[0063]

Table 2

[0064] <Evaluation Results of Aluminum Alloy Elongated Materials> As shown in Table 1 above, in Invention Examples 1 to 13, the content of components contained in the aluminum alloy elongated material (aluminum alloy part), the value calculated by the formula, and the average crystal grain size are within the ranges defined in the present invention, and the mechanical properties such as elongation and strength are improved.

[0065] On the other hand, as shown in Table 2 above, in Comparative Example 1 and Comparative Example 2, since the average crystal grain size became larger than the range defined in the present invention, the elongation became smaller.

[0066] In Comparative Example 3 and Comparative Example 4, the value α calculated from Formula (1) became smaller than the range defined in the present invention, and the solid solution amount and fine precipitates increased, so the strength increased and the elongation decreased. Further, since the average crystal grain size became larger than the range defined in the present invention, the elongation became smaller.

[0067] In Comparative Example 5, the Si content was less than the lower limit defined in the present invention, and the average crystal grain size became larger than the upper limit defined in the present invention. Therefore, the elongation became smaller. In Comparative Example 6 and Comparative Example 7, the value β calculated by Formula (2) became larger than the upper limit defined in the present invention, so that huge Mg 2 Si increased, and at the same time, the average crystal grain size became smaller than the lower limit defined in the present invention, so the elongation became smaller.

[0068] In Comparative Example 8, the Fe content is less than the lower limit specified in the present invention. Further, in Comparative Example 9, the Fe content and Mn content, in Comparative Example 10, the Cu content, in Comparative Example 11, the Mn content, and in Comparative Example 12, the Zn content exceed the upper limit specified in the present invention. Therefore, in all of Comparative Examples 8 to 12, the elongation became smaller compared to the Invention Examples.

[0069] Comparative Example 13 is an example in which 100% of the material scraps for automotive heat exchangers was used. Since the Mn content exceeded the upper limit specified in the present invention and the average crystal grain size became larger than the upper limit specified in the present invention, the elongation became smaller.

[0070] Comparative Example 14 is an example in which 100% of aluminum can scraps (UBC: Used Beverage Can) was used. Since the Si content was less than the lower limit specified in the present invention and the value α calculated from Formula (1) was less than the lower limit specified in the present invention, the elongation became smaller.

[0071] Comparative Example 15 is an example in which 100% of sash scraps was used. Since the Si content and Mn content were less than the lower limit specified in the present invention and the value α calculated by Formula (1) was less than the lower limit specified in the present invention, the tensile strength became low.

[0072] Comparative Example 16 is an example in which 100% of the alloy symbol AC4C material specified in JIS H 5202:2010 was used. Specifically, the Mn content is less than the lower limit specified in the present invention, the value β calculated by Formula (2) exceeds the upper limit of the range specified in the present invention, and the average crystal grain size is less than the lower limit specified in the present invention. Therefore, the tensile strength became low.

[0073] As shown by these results, in the aluminum alloy sheet material according to the present invention, the aluminum alloy part can be blended with various types of aluminum scraps at a high recycling rate, and the content of each component, the values α and β calculated from specific components, and the average crystal grain size are appropriately controlled. Therefore, whether it is a single-sheet sheet material composed only of the aluminum alloy part or a sheet material in which the aluminum alloy part and the skin material are laminated, mechanical properties such as elongation and strength are excellent, and particularly excellent elongation enables high formability to be obtained.

Claims

1. An aluminum alloy wrought material having an aluminum alloy part, The aluminum alloy portion has, with respect to the total mass of the aluminum alloy portion, Si: 1.0% by mass or more and 7.5% by mass or less, Fe: 0.15% by mass or more and 0.8% by mass or less, and Mn: 0.3% by mass or more and 1.0% by mass or less; Cu: 0.5% by mass or less, Mg: 2.0% by mass or less, Zn: 0.7% by mass or less; The balance is Al and unavoidable impurities, When the content of the Si relative to the total mass of the aluminum alloy portion is [Si] in mass%, and the content of the Mg relative to the total mass of the aluminum alloy portion is [Mg] in mass%, The value α calculated by the following formula (1) is 0 or more, and the value β calculated by the following formula (2) is 7.5 or less, An aluminum alloy wrought material, characterized in that the average crystal grain size in the aluminum alloy portion is 40 μm or more and 350 μm or less. Formula (1): α=[Si]-2×[Mg] Formula (2): β=[Si]+2.25×[Mg]

2. 2. The aluminum alloy wrought product according to claim 1, wherein the aluminum alloy portion has an average crystal grain size of 250 μm or less.

3. 3. The aluminum alloy wrought material according to claim 1, wherein the aluminum alloy portion has an average crystal grain size of 60 μm or more.

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