Aluminum alloy rolled plate and its manufacturing method

Abstract

To provide a rolled sheet of an aluminum alloy which has high strength and excellent moldability even in the case where the ratio of aluminum virgin metal in a casting raw material is reduced, and in the case where the aluminum virgin metal is not used as the casting raw material, and a method for manufacturing the same.SOLUTION: A rolled sheet of an aluminum alloy has a chemical component comprising 0.80 mass% or more and 2.5 mass% or less Si, 0.40 mass% or more and 1.2 mass% or less Mn, 0.25 mass% or more and 0.65 mass% or less Mg, and 0.050 mass% or more and 0.45 mass% or less Fe, and the remainder has Al and inevitable impurities. Uniform elongation in a direction perpendicular to a rolling direction of the rolled sheet of the aluminum alloy is 19.5% or more, and the value of anisotropy Δr of a Lankford value is -0.50 or more and 0 or less. The rolled sheet of the aluminum alloy has characteristics of 0.2% bearing force of 175 MP or more after having introduced a 2% pre-strain, and then subjected to aging treatment under conditions of a holding temperature of 170°C and retention time of 20 minutes.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aluminum alloy rolled sheet and a method for producing the same. [Background technology]

[0002] Although Al-Mg-Si (aluminum-magnesium-silicon) alloys have a specific gravity about one-third that of cold-rolled steel sheets, they have the same strength as cold-rolled steel sheets. Furthermore, Al-Mg-Si alloys have bake hardening properties, meaning that their strength improves when heated during painting and baking processes. Taking advantage of these properties, cold-rolled steel sheets are increasingly being replaced by aluminum alloy sheets containing magnesium in fields such as automotive body sheets and body panels, where weight reduction is strongly desired.

[0003] For example, Patent Document 1 discloses a steel sheet having a chemical composition containing Si: 0.60 to 1.8% (mass %, the same applies hereinafter), Mg: 0.20 to 1.0%, and the balance being Al and unavoidable impurities, and having an arithmetic mean roughness Ra of 0.30 μm or less, an r-value (Lankford value) in the rolling direction of r0, an r-value in the direction perpendicular to the rolling direction of r 90 , r value in the direction at 45° to the rolling direction is r 45 When the average value of r is ave (However, r ave =(r0+r 90 +r 45 ×2) / 4) is 0.70 or more, and the absolute value of the anisotropy of the r value Δr (where Δr = (r0 + r 90 -r 45 ×2) / 2) is less than 0.10, and the tensile strength in the rolling direction is σ0, and the tensile strength in the direction perpendicular to the rolling direction is σ 90 , tensile strength at 45° to the rolling direction is σ 45 When the average value of tensile strength is ave (However, σ ave =(σ0+σ 90 +σ 45 × 2) / 4) is 230 MPa or more, and the elongation in the rolling direction is δ0, and the elongation in the direction perpendicular to the rolling direction is δ 90 , and elongation at 45° to the rolling direction is δ45 When the average elongation δ ave (However, δ ave =(δ0+δ 90 +δ 45 The aluminum alloy plate has a ratio of 2) / 4) of 25% or more. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-210661 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, from the viewpoint of reducing environmental impact, it has become desirable to use aluminum scrap, such as discarded automotive aluminum products and scraps of automotive aluminum products, as a casting raw material when producing aluminum alloy sheets. However, the chemical composition of aluminum scrap is not uniform, and the types of elements contained in the aluminum scrap and the content of each element vary depending on the application of the aluminum scrap. In addition, aluminum scrap may sometimes be accompanied by parts whose main components are metals other than aluminum. Therefore, when aluminum scrap is used as at least a part of the casting raw material, the content of elements other than aluminum in the final aluminum alloy sheet tends to be high. Aluminum alloy sheets having such chemical compositions tend to have poor formability.

[0006] In particular, aluminum alloy sheets for automobile body sheets and body panels are required to have various excellent properties such as strength, formability, corrosion resistance, etc. Therefore, in producing aluminum alloy sheets for such applications, primary aluminum ingots with an aluminum purity of 99.9% or more are currently used as the casting raw material.

[0007] The present invention has been made in view of the above background, and aims to provide an aluminum alloy rolled sheet having high strength and excellent formability, even when the ratio of virgin aluminum ingots in the casting raw material is reduced, or even when virgin aluminum ingots are not used as the casting raw material, and a method for manufacturing the same. [Means for solving the problem]

[0008] One aspect of the present invention is a composition containing Si (silicon): 0.80% by mass or more and 2.5% by mass or less, Mn (manganese): 0.40% by mass or more and 1.2% by mass or less, and Mg (magnesium): 0.25% by mass or more and 0.65% by mass or less. 、 Fe (iron): 0.050% by mass or more and 0.45% by mass or less Cu (copper): 0.0010 mass% or more and 1.0 mass% or less, and Ti (titanium): 0.0050 mass% or more and 0.20 mass% or less Contains Further, it contains one or two elements selected from the group consisting of Cr (chromium): 0.0010 mass% or more and 0.10 mass% or less and Zn (zinc): 0.0010 mass% or more and 1.0 mass% or less, The balance is Al (aluminum) and unavoidable impurities, The uniform elongation in the direction perpendicular to the rolling direction is 19.5% or more, The steel has a characteristic that the 0.2% yield strength is 175 MPa or more after 2% pre-straining and then aging treatment at a holding temperature of 170°C for 20 minutes. The anisotropy Δr of the Lankford value, expressed by the following formula (1), is between -0.50 and 0. The Lankford value r at 45° to the rolling direction 45 is 0.45 or more, and the average value r of the Lankford value expressed by the following formula (2) ave is 0.65 or more , aluminum alloy rolled plate. Δr=(r0-2×r 45 +r 90 ) / twenty one) r ave =(r 0 +2×r 45 +r 90 ) / 4 ···(2)

[0009] In the above formula (1), r0 represents the Lankford value in the rolling direction. 、r 90 represents the Lankford value in the direction perpendicular to the rolling direction.

[0010] Another aspect of the present invention is a method for producing an aluminum alloy rolled sheet according to the above aspect, producing an ingot having the chemical composition; Thereafter, the ingot is hot-rolled to produce a hot-rolled sheet, After the hot rolling, the hot-rolled sheet is subjected to one or more passes of cold rolling without intermediate annealing to produce an aluminum alloy rolled sheet; The method for producing an aluminum alloy rolled sheet includes, after the cold rolling, heating the aluminum alloy rolled sheet and then quenching the aluminum alloy rolled sheet, thereby subjecting the aluminum alloy rolled sheet to a solution treatment. [Effects of the Invention]

[0011] The aluminum alloy rolled plate has the specific chemical composition and further has uniform elongation in a direction perpendicular to the rolling direction. 、 The aluminum alloy rolled sheet has mechanical properties in which the 0.2% proof stress and the anisotropy Δr of the Lankford coefficient (hereinafter referred to as "r-value") after the specific treatment fall within the specific ranges. Such an aluminum alloy rolled sheet has high strength and excellent formability even when the ratio of virgin aluminum in the casting raw material is reduced or when virgin aluminum is not used as the casting raw material.

[0012] In addition, in the method for producing an aluminum alloy rolled sheet, an ingot having the specific chemical composition is hot-rolled, and then the hot-rolled sheet is cold-rolled without intermediate annealing. This reduces the effect of elements other than the aluminum alloy on formability, even when the hot-rolled sheet contains a relatively large amount of elements other than the aluminum alloy. As a result, the production method makes it possible to easily produce an aluminum alloy rolled sheet having high strength and excellent formability, even when the proportion of virgin aluminum in the casting feedstock is reduced or when virgin aluminum is not used as the casting feedstock.

[0013] As described above, according to the above-described aspects, even when the ratio of virgin aluminum ingots in the casting raw material is reduced or when virgin aluminum ingots are not used as the casting raw material, it is possible to provide an aluminum alloy rolled sheet and a method for manufacturing the same that have high strength and excellent formability. DETAILED DESCRIPTION OF THE INVENTION

[0014] (rolled aluminum alloy plate) The chemical composition and properties of the aluminum alloy rolled plate will be described below.

[0015] [Chemical composition] The aluminum alloy rolled plate contains Si, Mn, Mg, and Fe as essential components.

[0016] ·Si: 0.80 mass% or more and 2.5 mass% or less The aluminum alloy rolled sheet has a Si content of 0.80% by mass or more and 2.5% by mass or less. A portion of the Si in the aluminum alloy rolled sheet is dissolved in the Al matrix. The Si dissolved in the Al matrix has the effect of increasing the increase in strength due to work hardening and also has the effect of improving the uniform elongation of the aluminum alloy rolled sheet.

[0017] Furthermore, Si that is not dissolved in the Al matrix exists as second-phase particles dispersed in the Al matrix. The second-phase particles containing Si are composed of, for example, simple Si, Mg2Si, an Al-(Fe, Mn)-Si intermetallic compound, an Al-Mn-Si intermetallic compound, or an Al-Fe-Si intermetallic compound. These second-phase particles serve as recrystallization nucleation sites during solution treatment in the manufacturing process of the aluminum alloy rolled sheet, and have the effect of suppressing the development of cube orientation in the aluminum alloy rolled sheet after solution treatment.

[0018] By setting the Si content in the aluminum alloy rolled sheet to 0.80% by mass or more, preferably 0.90% by mass or more, and more preferably 1.0% by mass or more, the uniform elongation of the aluminum alloy rolled sheet can be increased, and the anisotropy Δr of the r-value can be set within the specified range, thereby improving the formability of the aluminum alloy rolled sheet. Furthermore, by setting the Si content in the aluminum alloy rolled sheet to 0.80% by mass or more, the strength of the aluminum alloy rolled sheet can be improved. In addition, the proportion of virgin aluminum in the casting raw material can be easily reduced.

[0019] On the other hand, if the Si content in the rolled aluminum alloy sheet is excessively high, the amount of second-phase particles formed in the rolled aluminum alloy sheet will be excessively large, which may lead to deterioration of the formability of the rolled aluminum alloy sheet. By setting the Si content in the rolled aluminum alloy sheet to 2.5 mass% or less, preferably 2.3 mass% or less, and more preferably 2.1 mass% or less, it is possible to easily avoid deterioration of the formability of the rolled aluminum alloy sheet.

[0020] ·Mn: 0.40 mass% or more and 1.2 mass% or less The aluminum alloy rolled sheet has a Mn content of 0.40% by mass or more and 1.2% by mass or less. A portion of the Mn in the aluminum alloy rolled sheet is dissolved in the Al matrix. The dissolved Mn in the Al matrix has the effect of increasing the increase in strength due to work hardening and also has the effect of improving the uniform elongation of the aluminum alloy rolled sheet.

[0021] Furthermore, Mn that is not dissolved in the Al matrix exists as second-phase particles dispersed in the Al matrix. The Mn-containing second-phase particles are composed of, for example, an Al-(Fe, Mn)-Si intermetallic compound or an Al-Mn-Si intermetallic compound. As described above, these second-phase particles serve as recrystallization nucleation sites during solution treatment in the manufacturing process of the aluminum alloy rolled sheet, and have the effect of suppressing the development of Cube orientation in the aluminum alloy rolled sheet after solution treatment.

[0022] By setting the Mn content in the aluminum alloy rolled sheet to 0.40% by mass or more, the uniform elongation of the aluminum alloy rolled sheet can be increased, and the anisotropy Δr of the r-value can be set within the specified range, thereby improving the formability of the aluminum alloy rolled sheet. Furthermore, by setting the Mn content in the aluminum alloy rolled sheet to 0.40% by mass or more, the strength of the aluminum alloy rolled sheet can be improved. Furthermore, by setting the Mn content in the aluminum alloy rolled sheet to 0.40% by mass or more, the proportion of virgin aluminum in the casting raw material can be easily reduced. From the viewpoint of further enhancing these effects, the Mn content in the aluminum alloy rolled sheet is preferably 0.45% by mass or more, more preferably 0.50% by mass or more, even more preferably 0.55% by mass or more, particularly preferably more than 0.65% by mass, and most preferably 0.70% by mass or more.

[0023] On the other hand, if the Mn content in the aluminum alloy rolled sheet is excessively high, the amount of second-phase particles formed in the aluminum alloy rolled sheet will be excessively large, which may lead to deterioration of the formability of the aluminum alloy rolled sheet. By setting the Mn content in the aluminum alloy rolled sheet to 1.2 mass% or less, preferably 1.1 mass% or less, and more preferably 1.0 mass% or less, it is possible to easily avoid deterioration of the formability of the aluminum alloy rolled sheet.

[0024] ·Fe: 0.050 mass% or more and 0.45 mass% or less The Fe content in the aluminum alloy rolled sheet is 0.050% by mass or more and 0.45% by mass or less. The Fe in the aluminum alloy rolled sheet is mainly present as second-phase particles such as Al-Fe-Si intermetallic compounds and Al-(Fe, Mn)-Si intermetallic compounds. As described above, these second-phase particles serve as recrystallization nucleation sites during solution treatment in the manufacturing process of the aluminum alloy rolled sheet, and have the effect of suppressing the development of Cube orientation in the aluminum alloy rolled sheet after solution treatment.

[0025] By setting the Fe content in the aluminum alloy rolled sheet to 0.050% by mass or more, preferably 0.10% by mass or more, the anisotropy Δr of the r-value can be set within the specific range, thereby improving the formability of the aluminum alloy rolled sheet.

[0026] On the other hand, if the Fe content in the rolled aluminum alloy sheet is excessively high, Si and Mn are consumed by the formation of Al-Fe-Si intermetallic compounds and Al-(Fe, Mn)-Si intermetallic compounds, etc., and the amounts of Si and Mn dissolved in the rolled aluminum alloy sheet tend to decrease. Furthermore, a decrease in the amounts of Si and Mn dissolved in the rolled aluminum alloy sheet may result in a decrease in the strength and uniform elongation of the rolled aluminum alloy sheet. By setting the Fe content in the rolled aluminum alloy sheet to 0.45% by mass or less, preferably 0.40% by mass or less, this problem can be easily avoided.

[0027] ·Mg: 0.25 mass% or more and 0.65 mass% or less The aluminum alloy rolled sheet contains 0.25% by mass or more and 0.65% by mass or less of magnesium. In the aluminum alloy rolled sheet, magnesium is present mainly as second-phase particles such as MgSi, and has the effect of improving the strength of the aluminum alloy rolled sheet by precipitation strengthening.

[0028] By adjusting the Mg content in the aluminum alloy rolled sheet to 0.25% by mass or more, preferably 0.30% by mass or more, the strength of the aluminum alloy rolled sheet can be improved. If the Mg content is less than 0.25% by mass, the amount of GP zones formed during the manufacturing process of the aluminum alloy rolled sheet is reduced, and the effect of improving strength through precipitation strengthening is likely to be reduced. Therefore, in this case, there is a risk of the strength of the aluminum alloy rolled sheet being reduced.

[0029] On the other hand, if the Mg content is excessively high, coarse Mg-Si intermetallic compounds are likely to form in the rolled aluminum alloy sheet, which may lead to reduced strength, reduced elongation, and poor formability. These problems can be easily avoided by setting the Mg content in the rolled aluminum alloy sheet to 0.65% by mass or less, preferably 0.60% by mass or less, and more preferably 0.55% by mass or less.

[0030] The aluminum alloy rolled plate contains, in addition to the essential components Si, Mn, Fe and Mg, 、C u (copper) and Ti (titanium) and at least one element selected from the group consisting of Cr (chromium) and Zn (zinc). The aluminum alloy rolled sheet further contains, as optional components: The alloy may contain one or more elements selected from the group consisting of Zr (zirconium), Bi (bismuth) and B (boron).

[0031] For example, the aluminum alloy rolled sheet may have a chemical composition that contains Si: 0.80% by mass to 2.5% by mass, Mn: 0.40% by mass to 1.2% by mass, Mg: 0.25% by mass to 0.65% by mass, and Fe: 0.050% by mass to 0.45% by mass, and further contains one or more elements selected from the group consisting of Cu: 0.0010% by mass to 1.0% by mass, Cr: 0.0010% by mass to 0.10% by mass, Zn: 0.0010% by mass to 1.0% by mass, and Ti: 0.0050% by mass to 0.20% by mass, with the balance being Al and unavoidable impurities.

[0032] The aluminum alloy rolled sheet may have a chemical composition that contains at least 0.80% by mass and at most 2.5% by mass of Si, at least 0.40% by mass and at most 1.2% by mass of Mn, at least 0.25% by mass and at most 0.65% by mass of Mg, at least 0.050% by mass and at most 0.45% by mass of Fe, and further contains at least one element selected from the group consisting of at least 0.0010% by mass and at most 1.0% by mass of Cu, at least 0.0010% by mass and at most 0.10% by mass of Cr, at least 0.0010% by mass and at most 1.0% by mass of Zn, at least 0.0050% by mass and at most 0.20% by mass of Ti, at most 0% by mass and at most 0.10% by mass of Zr, and at most 0% by mass and at most 0.20% by mass of Bi, with the balance being Al and unavoidable impurities.

[0033] ·Cu: 0.0010 mass% or more and 1.0 mass% or less The aluminum alloy rolled plate 、0 Contains 0.0010% to 1.0% by mass of Cu There are In the aluminum alloy rolled sheet, a portion of Cu is dissolved in the Al matrix. Cu that is not dissolved in the Al matrix exists as second-phase particles containing Cu, such as Al-Cu-based particles. Cu dissolved in the Al matrix has the effect of increasing the increase in strength due to work hardening. By setting the Cu content in the aluminum alloy rolled sheet to preferably 0.0010% by mass or more, more preferably 0.010% by mass or more, and even more preferably 0.050% by mass or more, the increase in strength of the aluminum alloy rolled sheet due to work hardening can be increased.

[0034] On the other hand, if the Cu content is excessively high, the number of Cu-containing second-phase particles formed in the aluminum alloy rolled sheet is likely to increase. Since the Cu-containing second-phase particles are likely to become corrosion initiation points due to the natural potential difference with the Al matrix, if the Cu content is excessively high, the corrosion resistance of the aluminum alloy rolled sheet may be deteriorated. By setting the Cu content in the aluminum alloy rolled sheet to preferably 1.0 mass% or less, more preferably 0.40 mass% or less, even more preferably 0.19 mass% or less, and particularly preferably 0.14 mass% or less, it is possible to easily avoid deterioration in the corrosion resistance of the aluminum alloy rolled sheet.

[0035] Cr: 0.0010 mass% or more and 0.10 mass% or less The aluminum alloy rolled sheet may contain 0.0010% by mass or more and 0.10% by mass or less of Cr as an optional component. Cr has effects such as improving the strength of the aluminum alloy rolled sheet, refining crystal grains, and improving surface treatability. On the other hand, if the Cr content is excessively high, coarse second-phase particles composed of intermetallic compounds containing Cr are likely to be formed in the aluminum alloy rolled sheet. Such coarse second-phase particles are undesirable because they may deteriorate formability. By setting the Cr content in the aluminum alloy rolled sheet within the above-mentioned specific range, the above-mentioned effects can be obtained while avoiding the formation of coarse second-phase particles.

[0036] ·Zn: 0.0010 mass% or more and 1.0 mass% or less The aluminum alloy rolled sheet may contain 0.0010% by mass or more and 1.0% by mass or less of Zn as an optional component. Zn has effects such as improving the strength of the aluminum alloy rolled sheet, refining crystal grains, and improving surface treatability. On the other hand, an excessively high Zn content may lead to a deterioration in the corrosion resistance of the aluminum alloy rolled sheet. By setting the Zn content in the aluminum alloy rolled sheet within the above-mentioned specific range, it is possible to obtain the above-mentioned effects while avoiding a deterioration in corrosion resistance.

[0037] ·Ti: 0.0050 mass% or more and 0.20 mass% or less The aluminum alloy rolled plate 、0 Contains 0.0050 mass% or more and 0.20 mass% or less of Ti There are Ti has the effect of refining the ingot structure, suppressing cracking of the ingot during casting, and improving rollability during hot rolling. On the other hand, if the Ti content is excessively high, coarse crystallized particles made of intermetallic compounds containing Ti are likely to be formed in the ingot. Such coarse crystallized particles are undesirable because they may cause deterioration in rollability and formability.

[0038] By setting the Ti content in the aluminum alloy rolled sheet within the above-mentioned specific range, it is possible to obtain the above-mentioned effects while avoiding deterioration of rollability and formability. From the viewpoint of more reliably avoiding the formation of coarse crystallized particles, the Ti content is more preferably 0.15 mass% or less.

[0039] B: More than 0 mass ppm and 500 mass ppm or less When the aluminum alloy rolled plate contains Ti, it is preferable that the aluminum alloy rolled plate further contains more than 0 ppm by mass and not more than 500 ppm by mass of B. In this case, the effect of refining the ingot structure is further enhanced, and the formation of abnormal crystal grains such as columnar crystals during the casting process can be suppressed.

[0040] Other elements The aluminum rolled sheet may further contain one or more elements selected from the group consisting of more than 0 mass% and less than 0.10 mass% Zr and more than 0 mass% and less than 0.20 mass% Bi. The content of Bi in the aluminum rolled sheet is preferably 0.060 mass% or less. In this case, the corrosion resistance of the aluminum alloy rolled sheet can be further improved.

[0041] [Characteristics] Uniform elongation The aluminum alloy rolled sheet has a uniform elongation of 19.5% or more in a direction perpendicular to the rolling direction. Here, uniform elongation refers to the maximum value of permanent elongation at which the aluminum alloy rolled sheet is uniformly deformed when subjected to a tensile test. More specifically, the value of uniform elongation is the nominal strain value corresponding to the maximum test force when a tensile test is conducted according to the method specified in JIS Z2241:2011.

[0042] An aluminum alloy rolled sheet having a uniform elongation value of 19.5% or more is likely to deform uniformly even when subjected to a large deformation amount. Therefore, such an aluminum alloy rolled sheet has excellent formability and can be easily formed into a desired shape when subjected to forming processes such as stretch forming and deep drawing. From the viewpoint of further improving the formability of the aluminum alloy rolled sheet, the uniform elongation value is preferably 20.0% or more.

[0043] If the uniform elongation of the aluminum alloy rolled sheet is less than 19.5%, plastic instability such as necking may occur when the deformation amount increases, and the deformation of the aluminum alloy rolled sheet may become non-uniform. As a result, the formability of the aluminum alloy rolled sheet may deteriorate, forming defects may occur easily, and the appearance after forming may be deteriorated.

[0044] r-value The anisotropy Δr of the r-value of the aluminum alloy rolled sheet is −0.50 or more and 0 or less. Here, the anisotropy Δr of the r-value is the ratio of the r-value in the rolling direction r0 to the r-value in the direction at an angle of 45° to the rolling direction r 45 and r value in the direction perpendicular to the rolling direction 90 is used and is expressed by the following formula (1). Δr=(r0-2×r 45 +r 90 ) / twenty one)

[0045] In addition, the r value in the rolling direction r0, the r value in the direction at 45° to the rolling direction r 45 and r value in the direction perpendicular to the rolling direction 90The value of is the logarithmic strain in the width direction of the tensile test piece divided by the logarithmic strain in the thickness direction when a tensile test piece with each direction as the longitudinal direction is tensile deformed and a strain of, for example, 15% is applied.

[0046] The main crystal orientation in aluminum alloys is called the Cube orientation, and when the Cube orientation develops, the r value in the 45° direction to the rolling direction increases. 45 The value of r in the rolling direction r0 and the value of r perpendicular to the rolling direction r 90 In conventional Al-Mg-Si alloys, cube orientation tends to develop, and the r value in the 45° direction to the rolling direction tends to be lower than the r value. 45 Therefore, the anisotropy Δr of the r-value in conventional Al-Mg-Si alloys is usually positive.

[0047] In contrast, in the aluminum alloy rolled sheet, by subjecting an ingot having chemical compositions within the specific range to hot rolling, cold rolling and solution treatment in the manner described above, the development of cube orientation is suppressed, and the r value r in the 45° direction relative to the rolling direction is reduced. 45 The value of r in the direction at 45° to the rolling direction can be increased. 45 As a result of the increase in the value of , the anisotropy Δr of the r value can be set within the above-mentioned specific range.

[0048] An aluminum alloy rolled sheet having an r-value anisotropy Δr within the above-mentioned specific range has excellent formability and can be easily formed into a desired shape, for example, when subjected to forming processes such as square cup drawing. From the viewpoint of further enhancing such effects, that is, from the viewpoint of further improving the formability of the aluminum alloy rolled sheet, the value of the r-value anisotropy Δr is preferably −0.50 or more and −0.01 or less, more preferably −0.45 or more and −0.05 or less, and even more preferably −0.40 or more and −0.08 or less.

[0049] If the value of the anisotropy Δr of the r-value of the aluminum alloy rolled plate is outside the above-mentioned specific range, the formability of the aluminum alloy rolled plate will be deteriorated, forming defects will be more likely to occur, and there is a risk that the appearance after forming will be deteriorated.

[0050] From the viewpoint of further improving the formability of aluminum alloy rolled sheets, the r value r in the direction at 45° to the rolling direction is 45 is 0.45 or more From the same viewpoint, the r value r in the direction at 45° to the rolling direction 45 teeth It is more preferably 0.55 or more, even more preferably 0.65 or more, and particularly preferably 0.75 or more.

[0051] From the same viewpoint, the average value of r expressed by the following formula (2) is 0.65 or more. The average value of r is It is more preferable that it is 0.70 or more. r ave =(r0+2×r 45 +r 90 ) / 4 ···(2)

[0052] Tensile strength, 0.2% yield strength and elongation at break The tensile strength TS of the aluminum alloy rolled plate in the direction perpendicular to the rolling direction is preferably 190 MPa or more, more preferably 230 MPa or more, which can further improve the strength of aluminum products produced using the aluminum alloy rolled plate.

[0053] The rolled aluminum alloy sheet preferably has a 0.2% yield strength YS in a direction perpendicular to the rolling direction of 100 MPa or more, which can further improve the rigidity of aluminum products produced using the rolled aluminum alloy sheet.

[0054] On the other hand, from the viewpoint of further improving the formability of the aluminum alloy rolled sheet, the 0.2% proof stress YS in the direction perpendicular to the rolling direction of the aluminum alloy rolled sheet is preferably 160 MPa or less.

[0055] Furthermore, the difference (TS-YS) between the tensile strength (TS) and the 0.2% proof stress (YS) is preferably 110 MPa or more, more preferably 125 MPa or more, which further improves the formability of the aluminum alloy rolled sheet, and makes it easier to form it into a desired shape when performing forming processes such as deep drawing.

[0056] Furthermore, the elongation at break in the direction perpendicular to the rolling direction of the aluminum alloy rolled plate is preferably 22% or more, and more preferably 23% or more, which can further improve the formability of the aluminum alloy rolled plate.

[0057] The elongation at break refers to the permanent elongation after a rolled aluminum alloy sheet breaks when subjected to a tensile test. More specifically, the elongation at break is the nominal strain at the time when the test piece breaks when a tensile test is performed according to the method specified in JIS Z2241:2011.

[0058] 0.2% yield strength after pre-straining and aging treatment The aluminum alloy rolled sheet has a property that after 2% pre-strain is introduced and then aging treatment is performed under conditions of a holding temperature of 170°C and a holding time of 20 minutes, the 0.2% proof stress (hereinafter referred to as "BHYS") in the direction perpendicular to the rolling direction is 175 MPa or more. The BHYS value is an index of strength after the aluminum alloy rolled sheet is press-formed and then painted and baked.

[0059] When an aluminum alloy rolled sheet is used as an automotive body panel or body sheet, the aluminum alloy rolled sheet is usually press-formed and then baked. Therefore, increasing the strength of the aluminum alloy rolled sheet after baked is advantageous in increasing the degree of freedom in product design, making it possible to apply the aluminum alloy rolled sheet to a variety of locations. Therefore, an aluminum alloy rolled sheet having a BHYS value of 175 MPa or more has excellent strength after baked and is suitable for use as an automotive exterior material, such as an automotive body panel or body sheet. From the viewpoint of further increasing the degree of freedom in product design, the BHYS value is preferably 180 MPa or more, and more preferably 190 MPa or more.

[0060] [Thickness of aluminum alloy rolled plate] The thickness of the aluminum alloy rolled plate is not particularly limited and can be appropriately set depending on the application. For example, when the aluminum alloy rolled plate is used as an automotive exterior material such as an automobile body panel or body sheet, the thickness of the aluminum alloy rolled plate can be appropriately set in the range of 0.5 to 2.5 mm.

[0061] (Method of manufacturing aluminum alloy rolled sheet) When producing the aluminum alloy rolled plate, producing an ingot having the chemical composition; Thereafter, the ingot is hot-rolled to produce a hot-rolled sheet, After the hot rolling, the hot-rolled sheet is subjected to one or more passes of cold rolling without intermediate annealing to produce an aluminum alloy rolled sheet; After the cold rolling, the aluminum alloy rolled sheet may be heated and then quenched, thereby subjecting the aluminum alloy rolled sheet to a solution treatment. Each step of the method for producing the aluminum alloy rolled sheet will now be described in detail.

[0062] - Ingot production In the above-described production method, the method for producing the ingot is not particularly limited. For example, in the above-described production method, the ingot may be produced by DC casting.

[0063] In the manufacturing method, it is preferable to use scrap aluminum as at least a part of the casting raw material when producing an ingot. By using scrap aluminum as at least a part of the casting raw material, it is possible to produce an ingot by reducing the proportion of virgin aluminum ingot in the casting raw material, or by using no virgin aluminum ingot at all. As a result, it is possible to reduce the environmental load when producing the aluminum alloy rolled sheet. From the viewpoint of further enhancing this effect, it is preferable that the proportion of scrap aluminum in the casting raw material is 50 mass% or more, more preferably 75 mass% or more, and most preferably 100 mass%, i.e., the entire casting raw material is scrap aluminum.

[0064] Examples of aluminum scrap that can be used as a casting raw material in the manufacturing method include discarded aluminum automotive products and scraps and chips generated during the manufacturing process of aluminum automotive products. The aluminum scrap may also contain parts primarily composed of metals other than aluminum, such as rivets used to connect other parts. Examples of the aforementioned aluminum automotive products include body panels, heat exchangers, heat exchanger fins, heat exchanger tubes, and engine blocks.

[0065] Homogenization In the manufacturing method, after producing the ingot, the ingot may be heated and subjected to a homogenization treatment as needed before hot rolling. When the homogenization treatment is performed, the ingot is preferably held at a temperature of 480°C or higher and 560°C or lower for 0.5 hours or longer and 24 hours or shorter. By setting the holding temperature and holding time in the homogenization treatment within the above-mentioned specific ranges, elements such as Si, Mn, and Mg can be sufficiently solid-dissolved in the Al matrix. As a result, the strength and formability of the aluminum alloy rolled sheet can be further improved.

[0066] Furthermore, when homogenization treatment is performed, the ingot after the homogenization treatment is preferably cooled at an average cooling rate of 55°C / hour or more until the temperature of the ingot reaches 300°C, more preferably 60°C / hour or more, and particularly preferably 100°C / hour or more. By cooling the ingot after the homogenization treatment at an average cooling rate within the above-mentioned specific range, coarsening of second-phase particles such as MgSi and simple Si formed in the ingot can be suppressed, and a decrease in the solid solution amounts of elements such as Si, Mg, and Mn can be suppressed, thereby further improving the strength and formability of the aluminum alloy rolled sheet obtained. The cooling method after the homogenization treatment is not particularly limited and can be appropriately selected from cooling methods such as fan air cooling, mist cooling, shower cooling, and water cooling.

[0067] From the viewpoint of further increasing the productivity of the aluminum alloy rolled sheet and further reducing the amount of energy consumed in the manufacturing process, it is preferable to produce an ingot and then subject the ingot to hot rolling without performing a homogenization treatment.

[0068] Hot rolling In the manufacturing method, a hot-rolled sheet is produced by hot-rolling an ingot. When hot-rolling, the ingot is preferably heated to a temperature of 300°C or higher and 560°C or lower before the start of rolling. By setting the heating temperature of the ingot before hot-rolling within the above-mentioned specific range, the deformation resistance of the ingot can be reduced, and the rolling properties and productivity can be improved, and the occurrence of cracks in the ingot during hot rolling can be suppressed. From the viewpoint of more reliably obtaining these effects, it is more preferable to heat the ingot before the start of rolling to a temperature of 300°C or higher and 560°C or lower and hold the temperature for 0.5 hours to 24 hours before hot-rolling.

[0069] Furthermore, the heating temperature of the ingot before hot rolling is more preferably 500°C or higher and 560°C or lower, and even more preferably 510°C or higher and 560°C or lower. In this case, elements such as Si, Mn, and Mg can be solid-dissolved in the Al matrix by heating before hot rolling, as in the case of the homogenization treatment described above. As a result, even when the homogenization treatment is omitted, the formability of the rolled aluminum alloy sheet can be improved. From the viewpoint of more reliably obtaining such effects, it is more preferable to hold the ingot at a temperature of 500°C or higher and 560°C or lower for 0.5 hours or higher and 24 hours or lower before hot rolling, and even more preferable to hold the ingot at a temperature of 500°C or higher and 560°C or lower for 2 hours or higher and 12 hours or lower before hot rolling.

[0070] The temperature of the hot-rolled sheet at the end of hot rolling is not particularly limited, but from the viewpoint of productivity, it may be in the range of 200°C or higher and 350°C or lower, for example.

[0071] Cold rolling In the manufacturing method, an aluminum alloy rolled sheet is produced by hot rolling the hot-rolled sheet and then performing one or more passes of cold rolling without intermediate annealing. Here, intermediate annealing refers to annealing performed after hot rolling and before the completion of cold rolling. In the manufacturing method, cold rolling the hot-rolled sheet without intermediate annealing suppresses the precipitation and growth of second-phase particles in the hot-rolled sheet due to annealing, and cold rolling can be performed while maintaining the amount of solid solution elements such as Si in the Al matrix. Then, by performing a solution treatment described below on the aluminum alloy rolled sheet obtained in this manner, the amount of solid solution elements such as Si can be further increased, thereby improving the strength and formability of the aluminum alloy rolled sheet obtained finally.

[0072] The total reduction in cold rolling, i.e., the ratio of the thickness reduction in cold rolling to the thickness of the hot-rolled sheet, is preferably 50% or more, and more preferably 66% or more. By setting the total reduction in cold rolling within the above-mentioned specific range, second-phase particles present in the hot-rolled sheet can be crushed during cold rolling. As a result, it is possible to easily prevent coarse second-phase particles from remaining in the rolled aluminum alloy sheet, and to more easily avoid the reduction in uniform elongation and deterioration of formability that result from the coarse second-phase particles.

[0073] Solution treatment In the manufacturing method, the cold-rolled aluminum alloy rolled sheet is heated to a temperature equal to or higher than the solution temperature, and then quenched, thereby subjecting the aluminum alloy rolled sheet to solution treatment. By subjecting the aluminum alloy rolled sheet to solution treatment, the aluminum alloy rolled sheet becomes a supersaturated solid solution of Si, Mg, etc., thereby increasing the amount of solid solution of Si, Mn, Mg, etc., and reducing the amount of second-phase particles present in the aluminum alloy rolled sheet. As a result, the strength and formability of the aluminum alloy rolled sheet can be improved. From the viewpoint of more reliably achieving these effects, the treatment temperature of the aluminum alloy rolled sheet in the solution treatment is preferably 450°C or higher and 560°C or lower, more preferably 500°C or higher and 560°C or lower, and even more preferably 520°C or higher and 560°C or lower.

[0074] In the solution treatment, heating may be terminated when the temperature of the aluminum alloy rolled sheet reaches a desired temperature, or may be terminated after the desired temperature is maintained for a certain period of time. However, if the temperature of the aluminum alloy rolled sheet is maintained for an excessively long time in the solution treatment, productivity may be reduced and the strength of the aluminum alloy rolled sheet may be excessively increased, resulting in deterioration of formability. From the viewpoint of avoiding such problems, the temperature of the aluminum alloy rolled sheet is maintained for a period of time of preferably 1 minute or less, more preferably 5 seconds or less, and even more preferably 1 second or less.

[0075] Furthermore, in the solution treatment, quenching is performed immediately after the heating of the aluminum alloy rolled sheet is completed. This suppresses the precipitation and growth of second-phase particles in the aluminum alloy rolled sheet, and prevents a decrease in the amount of solid solution of Si and the like. As a result, an aluminum alloy rolled sheet with excellent formability can be easily obtained. From the viewpoint of more reliably achieving these effects, it is preferable to cool the aluminum alloy rolled sheet so that the average cooling rate from the temperature at the end of heating to 150°C is 100°C / min or more, and more preferably 300°C / min or more. The cooling method in quenching is not particularly limited and can be appropriately selected from cooling methods such as fan cooling, mist cooling, shower cooling, and water cooling.

[0076] Pre-aging treatment In the above-described manufacturing method, the aluminum alloy rolled sheet after the solution treatment may be subjected to a pre-aging treatment, if necessary. By further subjecting the aluminum alloy rolled sheet to a pre-aging treatment, the bake hardenability of the aluminum alloy rolled sheet can be further improved, and the increase in strength of the aluminum alloy rolled sheet by paint baking can be further increased. From the viewpoint of more reliably obtaining such effects, it is preferable to perform the pre-aging treatment immediately after the solution treatment.

[0077] In addition, in the pre-aging treatment, it is preferable to hold the aluminum alloy rolled sheet at a temperature of 40°C or higher and 150°C or lower for 1 hour or higher and 100 hours or lower. In this case, the bake hardening property of the aluminum alloy rolled sheet can be further improved, and an excessive increase in strength and a decrease in elongation of the aluminum alloy rolled sheet after the pre-aging treatment can be avoided. As a result, it is possible to further improve the bake hardening property while ensuring excellent formability. From the viewpoint of further enhancing these effects, the holding temperature in the pre-aging treatment is more preferably 40°C or higher and 100°C or lower, and even more preferably 60°C or higher and 90°C or lower. [Example]

[0078] Examples of the aluminum alloy rolled sheet and its manufacturing method are described below. The aluminum alloy rolled sheet of this example has a chemical composition containing Si: 0.80% by mass to 2.5% by mass, Mn: 0.40% by mass to 1.2% by mass, Mg: 0.25% by mass to 0.65% by mass, and Fe: 0.050% by mass to 0.45% by mass, with the balance being Al and unavoidable impurities. The aluminum alloy rolled sheet has a uniform elongation of 19.5% or more in a direction perpendicular to the rolling direction, and a Lankford anisotropy Δr value expressed by the following formula (1) of -0.50 to 0.001. The aluminum alloy rolled sheet also has a property that, after 2% pre-straining and subsequent aging treatment under conditions of a holding temperature of 170°C and a holding time of 20 minutes, the 0.2% proof stress in the direction perpendicular to the rolling direction is 175 MPa or more. Δr=(r0-2×r 45 +r 90 ) / twenty one)

[0079] In the above formula (1), r0 represents the Lankford value in the rolling direction, and r 45 represents the Lankford value at 45° to the rolling direction, and r 90 represents the Lankford value in the direction perpendicular to the rolling direction.

[0080] The aluminum alloy rolled sheet of this example is produced, for example, as follows. First, an ingot having the chemical composition (alloy symbols A1 to A7) shown in Table 1 is produced by DC casting. In Table 1, "Bal." indicates that the relevant element is the balance. When producing the ingot, either virgin aluminum or scrap aluminum can be used as the casting raw material, but from the perspective of reducing the environmental load, it is preferable to increase the proportion of scrap aluminum in the casting raw material.

[0081] Next, the obtained ingot is heated to one of the temperatures shown in Table 2 under manufacturing condition symbols C1 to C3 without being subjected to a homogenization treatment, and the temperature is maintained for the time shown in Table 2, after which the ingot is hot rolled. The temperature of the hot-rolled sheet at the completion of hot rolling is as shown in Table 2. Thereafter, the hot-rolled sheet obtained by hot rolling is cold-rolled without intermediate annealing. The total reduction in cold rolling and the thickness of the aluminum alloy rolled sheet after cold rolling are as shown in Table 2.

[0082] After the cold rolling is completed, the aluminum alloy rolled sheet is subjected to a solution treatment. In the solution treatment, the aluminum alloy rolled sheet is heated to a treatment temperature shown in any one of the manufacturing condition symbols C1 to C3 in Table 2, and the heating is terminated when the temperature of the aluminum alloy rolled sheet reaches the treatment temperature. Then, immediately after the heating is terminated, the aluminum alloy rolled sheet is quenched. In the quenching, the aluminum alloy rolled sheet is cooled from the temperature at the end of heating to 150°C at an average cooling rate of 600°C / min or more and 1000°C / min or less.

[0083] Immediately after the solution treatment is completed, the aluminum alloy rolled sheet is subjected to a pre-aging treatment by being held at a temperature of 70° C. or more and 80° C. or less for 5 hours. By the above steps, test materials S1 to S7 shown in Table 3 can be obtained.

[0084] Test materials R1 to R5 shown in Table 3 are test materials for comparison with test materials S1 to S7. The manufacturing method of test materials R1 to R3 is the same as that of test materials S1 to S7, except that the chemical components and manufacturing conditions were changed as shown in Table 3.

[0085] The manufacturing method for test material R4 is as follows. First, an ingot having the chemical composition shown in alloy symbol A11 in Table 1 is produced by DC casting. Next, the ingot is subjected to a homogenization treatment. The holding temperature and holding time in the homogenization treatment are as shown in manufacturing condition symbol C6 in Table 2. After the homogenization treatment, the ingot is cooled to room temperature at an average cooling rate of 300°C / hour. The ingot is then reheated to the temperature shown in Table 2 and held at that temperature for the time shown in Table 2, after which the ingot is hot rolled. The temperature of the hot-rolled sheet at the end of hot rolling is as shown in Table 2.

[0086] After the hot rolling is completed, the hot-rolled sheet is heated to 350°C and subjected to intermediate annealing. After the intermediate annealing is completed, the hot-rolled sheet is subjected to cold rolling under the conditions shown in manufacturing condition symbol C6 in Table 2. After the cold rolling is completed, the aluminum alloy rolled sheet is subjected to solution treatment and pre-aging treatment in the same manner as the test materials S1 to S7, thereby obtaining the test material R4.

[0087] The manufacturing method for test material R5 is as follows. First, an ingot having the chemical composition shown in alloy symbol A12 in Table 1 is produced by DC casting. Next, the ingot is subjected to a homogenization treatment. The holding temperature and holding time in the homogenization treatment are as shown in manufacturing condition symbol C7 in Table 2. After the homogenization treatment, the ingot is cooled to room temperature at an average cooling rate of 50°C / hour. The ingot is then reheated to the temperature shown in Table 2 and held at that temperature for the time shown in Table 2, after which the ingot is hot rolled. The temperature of the hot-rolled sheet at the end of hot rolling is as shown in Table 2.

[0088] After the hot rolling is completed, the hot-rolled sheet is subjected to cold rolling without intermediate annealing. The total reduction in cold rolling and the thickness of the aluminum alloy rolled sheet after cold rolling are as shown in Table 2. After the cold rolling is completed, the aluminum alloy rolled sheet is subjected to solution treatment and pre-aging treatment in the same manner as the test materials S1 to S7, thereby obtaining the test material R5.

[0089] The tensile strength, 0.2% yield strength, elongation at break, uniform elongation, BHYS, r value and corrosion resistance of the test materials S1 to S5 and the test materials R1 to R5 were evaluated as follows.

[0090] Tensile strength, 0.2% yield strength, elongation at break and uniform elongation

[0091] A No. 5 test piece as specified in JIS Z2241:2011 is taken from the test material so that the longitudinal direction is perpendicular to the rolling direction. Using this test piece, a tensile test is carried out using a method in accordance with JIS Z2241:2011, and the tensile strength in the direction perpendicular to the rolling direction, TS 90 (unit: MPa), 0.2% yield strength YS 90 (unit: MPa), elongation at break EL 90 (unit:%), uniform elongation UL 90 (Unit: %) was calculated. These values ​​for each test material are shown in Table 3.

[0092] 0.2% yield strength (BHYS) after pre-straining and aging

[0093] No. 5 test pieces, as specified in JIS Z2241:2011, are taken from the test material with the longitudinal direction perpendicular to the rolling direction. A tensile test is performed using a method in accordance with JIS Z2241:2011 until a nominal strain of 2% is reached. The test piece is then immersed in an oil bath at 170°C for 20 minutes for aging treatment. A tensile test is then performed on the test piece after pre-straining and aging treatment using a method in accordance with JIS Z2241:2011. The 0.2% proof stress (unit: MPa) calculated from the above is the BHYS value. The BHYS values ​​for each test material are as shown in Table 3.

[0094] r-value A No. 5 test piece as specified in JIS Z2241:2011 is taken from the test material so that the longitudinal direction and the rolling direction are parallel. Using this test piece, a tensile test is performed using a method in accordance with JIS Z2241:2011, and a nominal strain of 15% is applied to the test piece. Then, the logarithmic strain in the longitudinal direction and the logarithmic strain in the width direction of the test piece after the nominal strain is applied is calculated. Assuming that the volume of the test piece is constant, the logarithmic strain in the longitudinal direction of the test piece, ε l , logarithmic strain in the width direction εw and logarithmic strain ε in the thickness direction t Between ε t =-(ε l +ε w ) relationship holds, the r value r0 in the direction parallel to the rolling direction can be calculated based on the logarithmic strain in the longitudinal direction and the logarithmic strain in the width direction of the test piece.

[0095] By conducting a tensile test in the same manner as above using a No. 5 test piece in which the angle between the longitudinal direction and the rolling direction is 45° and a test piece in which the longitudinal direction is perpendicular to the rolling direction, the r value in the direction inclined at 45° to the rolling direction was measured. 45 and the r value in the direction perpendicular to the rolling direction, r 90 Using these values, the anisotropy Δr of the rr values ​​and the average value r of the r values ​​can be calculated based on the following formulas (1) and (2). ave Calculate the r-value, anisotropy Δr of the r-value, and average value r of the r-value for each test material. ave are as shown in Table 3. For test materials R3 to R5, the r-value was not measured, so the r-value in each direction, the anisotropy Δr of the r-value, and the average value r of the r-value are ave The symbol "-" was entered in the column. Δr=(r0-2×r 45 +r 90 ) / twenty one) r ave =(r0+2×r 45 +r 90 ) / 4 ···(2)

[0096] Corrosion resistance To evaluate corrosion resistance, an intergranular corrosion test is conducted in accordance with Method B specified in ISO 11846. Specifically, a rectangular test piece 20 mm long and 50 mm wide is first taken from the test material. This test piece is then aged in an oven at 170°C for 20 minutes. After aging, the test piece is washed with nitric acid and then with distilled water. The test piece is then immersed for 20 hours in an aqueous solution containing 30 g / L of NaCl and 10 ml / L of HCl at 20°C. After 20 hours of immersion, the test piece is removed from the aqueous solution.

[0097] The test specimens removed from the aqueous solution were washed with nitric acid and then with distilled water. The cross sections of the test specimens parallel to the rolling direction were then observed, and the intergranular corrosion depth was measured. The maximum intergranular corrosion depth in the observed cross sections is shown in the "Maximum intergranular corrosion depth" column of Table 3. Note that for test materials S1, S7, and R2 to R4, no intergranular corrosion tests were conducted, and therefore the symbol "-" was entered in the "Maximum intergranular corrosion depth" column.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] As shown in Table 3, test materials S1 to S7 were produced by hot rolling, cold rolling, solution treatment, and pre-aging of ingots having the specific chemical compositions described above, without intermediate annealing. This allows the BHYS, uniform elongation, and r-value anisotropy Δr of test materials S1 to S7 to be within the specific ranges described above. Test materials S1 to S7 with such mechanical properties have high strength and excellent formability.

[0102] Because the Mn content and Ti content in test material R1 are higher than the specific ranges, the uniform elongation of test material R1 is lower than those of test materials S1 to S7, and therefore test material R1 has inferior formability compared to test materials S1 to S7.

[0103] Because the Si content in test material R2 is higher than the specific range, the uniform elongation of test material R2 is lower than that of test materials S1 to S7, and therefore test material R2 has inferior formability compared to test materials S1 to S7.

[0104] Because the Fe content and Mg content in test material R3 are higher than the specific ranges, the uniform elongation of test material R3 is lower than those of test materials S1 to S7, and therefore test material R3 has inferior formability compared to test materials S1 to S7.

[0105] The Si content and Mn content of test material R4 are lower than the specific ranges, and the Mg content is higher than the specific ranges, so the BHYS of test material R3 is lower than that of test materials S1 to S7. Therefore, test material R3 has inferior strength after baking finish compared to test materials S1 to S7.

[0106] Because the average cooling rate of test material R5 after homogenization treatment is slow, the uniform elongation and BHYS of test material R5 are lower than those of test materials S1 to S5. Therefore, test material R5 is inferior in strength and formability to test materials S1 to S7.

[0107] Specific embodiments of the aluminum alloy rolled sheet and the method for manufacturing the same according to the present invention have been described above based on the examples. However, the specific embodiments of the aluminum alloy rolled sheet and the method for manufacturing the same according to the present invention are not limited to the embodiments, and the configurations can be changed as appropriate within the scope that does not impair the spirit of the present invention.

Claims

1. The alloy has a chemical composition comprising Si: 0.80% by mass or more and 2.5% by mass or less, Mn: 0.40% by mass or more and 1.2% by mass or less, Mg: 0.25% by mass or more and 0.65% by mass or less, Fe: 0.050% by mass or more and 0.45% by mass or less, Cu: 0.0010% by mass or more and 1.0% by mass or less, and Ti: 0.0050% by mass or more and 0.20% by mass or less, and further comprising one or two elements selected from the group consisting of Cr: 0.0010% by mass or more and 0.10% by mass or less and Zn: 0.0010% by mass or more and 1.0% by mass or less, with the balance being Al and unavoidable impurities; The uniform elongation value in the direction perpendicular to the rolling direction is 19.5% or more, The steel sheet has a property that after introducing a 2% pre-strain and then carrying out an aging treatment under conditions of a holding temperature of 170°C and a holding time of 20 minutes, the 0.2% proof stress in the direction perpendicular to the rolling direction is 175 MPa or more, An aluminum alloy rolled sheet having a Lankford value anisotropy Δr expressed by the following formula (1) of -0.50 or more and 0 or less, a Lankford value r 45 in a direction at 45° to the rolling direction of 0.45 or more, and an average Lankford value r ave expressed by the following formula (2) of 0.65 or more. Δr=(r 0 -2×r 45 +r 90 ) / 2 ・・・(1) r ave = (r 0 +2 x r 45 + r 90 ) / 4...(2) (However, r in the above formula (1) and formula (2) 0 represents the Lankford value in the rolling direction, and r 90 represents the Lankford value in the direction perpendicular to the rolling direction.)

2. 2. The aluminum alloy rolled sheet according to claim 1, wherein the Cu content in the aluminum alloy rolled sheet is less than 0.40 mass%.

3. 3. The aluminum alloy rolled sheet according to claim 1, wherein the aluminum alloy rolled sheet contains Ti: 0.0050% by mass or more and 0.20% by mass or less, and B: more than 0 ppm by mass and 500 ppm by mass or less.

4. The aluminum alloy rolled plate according to any one of claims 1 to 3, further containing one or two elements selected from the group consisting of Zr: more than 0 mass% and less than 0.10 mass% and Bi: more than 0 mass% and less than 0.20 mass%. The aluminum alloy rolled plate according to any one of claims 1 to 3.

5. The aluminum alloy rolled plate according to any one of claims 1 to 4, wherein the aluminum alloy rolled plate has a tensile strength TS in a direction perpendicular to the rolling direction of 230 MPa or more, and a difference TS - YS between the tensile strength TS and a 0.2% yield strength YS of 110 MPa or more.

6. A method for producing an aluminum alloy rolled sheet according to any one of claims 1 to 5, comprising: producing an ingot having the chemical composition; Thereafter, the ingot is hot-rolled to produce a hot-rolled sheet, After the hot rolling, the hot-rolled sheet is subjected to one or more passes of cold rolling without intermediate annealing to produce an aluminum alloy rolled sheet; the method for producing an aluminum alloy rolled plate, wherein after the cold rolling, the aluminum alloy rolled plate is heated and then quenched, thereby subjecting the aluminum alloy rolled plate to a solution treatment.

7. The method for producing an aluminum alloy rolled sheet according to claim 6, wherein scrap aluminum is used as at least a part of a casting raw material when the ingot is produced.

Images