JP2005139530A - Method of producing aluminum alloy sheet for forming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing an aluminum alloy sheet for forming which has satisfactory hem bendability, and reduced anisotropy in the bending. <P>SOLUTION: At the time of DC casting for an Al-Mg-Si based alloy, after solidification, the temperature lowering speed at 600 to 400°C is controlled to ≥30°C/min in the surface of the slab, and to ≥5°C/min in the center of the slab thickness. Next, it is heated at 300 to 450°C and is hot-rolled. In the hot rolling process, the amount of the temperature to be lowered to a thickness of 100 mm is controlled to ≤150°C, and the hot rolling is finished at 200 to 330°C. Then, cold rolling of ≥30%, solution treatment and stabilization treatment are performed, thus the aluminum alloy sheet in which the density of cube orientation is 30 to 250 times that of a random sample, the orientation density in the case the cube ideal orientation is rotated by 10° with an RD axis as the standard is higher than that in the case the cube ideal orientation is rotated by 10° with an ND axis as the standard, each earing ratio at 0° and 90° is ≥5%, the r value in the rolling direction is 0.50 to 1.50, the r value in the 45° direction is 0.01 to 0.45, the r value in the 90° direction is 0.60 to 3.50, and electrical conductivity is 54% IACS or lower is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この発明は、自動車ボディシートやそのほか各種自動車部品、各種機械器具、家電製品やその部品等の素材として、成形加工および塗装焼付を施して使用されるＡｌ−Ｍｇ−Ｓｉ系のアルミニウム合金板およびその製造方法に関するものであり、成形性、特にヘム曲げ性が良好であるとともに、塗装焼付後の強度が高く、かつ室温での経時変化が少ない成形加工用アルミニウム合金板を製造する方法に関するものである。   The present invention relates to an Al-Mg-Si-based aluminum alloy plate used as a material for an automobile body sheet, other various automobile parts, various machinery and equipment, home appliances and parts thereof, and the like, and subjected to forming and baking. The present invention relates to a production method, and relates to a method for producing an aluminum alloy sheet for forming that has good formability, particularly hem bendability, high strength after baking, and little change with time at room temperature. .

従来自動車のボディシートとしては、主として冷延鋼板を使用することが多かったが、最近では車体軽量化等の観点から、アルミニウム合金圧延板を使用することが多くなっている。ところで自動車のボディシートはプレス加工を施して使用するところから、成形加工性が優れていること、また成形加工時におけるリューダースマークが発生しないことが要求され、また高強度を有することも必須であって、塗装焼付を施して使用するのが通常であるため、塗装焼付後に高強度が得られることが要求される。そしてまた成形性が良好であることが要求されるのはもちろんであるが、自動車用ボディシートとしては、接合のためにヘム曲げ加工を施して使用することが多いところから、成形性のうちでも特にヘム曲げ性が優れていることが強く要求される。   Conventionally, as a body sheet of an automobile, a cold-rolled steel sheet has been mainly used, but recently, an aluminum alloy rolled sheet is frequently used from the viewpoint of reducing the weight of the vehicle body. By the way, since the body sheet of an automobile is used after being pressed, it is required that it has excellent molding processability, that no Ruders mark is generated during the molding process, and that it must have high strength. Since it is usually used after being baked, it is required to obtain high strength after baking. Of course, good formability is required, but as a body sheet for automobiles, it is often used after being subjected to hem bending for joining. In particular, there is a strong demand for excellent hem bendability.

従来このような自動車用ボディシート向けのアルミニウム合金としては、Ａｌ−Ｍｇ系合金のほか、時効性を有するＡｌ−Ｍｇ−Ｓｉ系合金が主として使用されている。この時効性Ａｌ−Ｍｇ−Ｓｉ系合金は、塗装焼付前の成形加工時においては比較的強度が低くて成形性が優れている一方、塗装焼付時の加熱によって時効されて塗装焼付後の強度が高くなる利点を有するほか、リューダースマークが発生しない等の利点を有する。   Conventionally, as an aluminum alloy for an automobile body sheet, an Al—Mg—Si alloy having aging properties is mainly used in addition to an Al—Mg alloy. This aging Al-Mg-Si alloy has a relatively low strength and excellent formability during molding before coating baking, while it is aged by heating during coating baking and has a strength after coating baking. In addition to the advantage that it becomes higher, it has the advantage that a Ruders mark does not occur.

なお、曲げ加工性向上に関する従来技術としては、鋳塊均質化処理後の冷却速度を制御することにより化合物分散状態を制御する特許文献１の技術、結晶粒界の方位差が１５°以下あるいは２０°以下の結晶粒界の割合を規制する特許文献２、特許文献３等がある。また本発明者等も既に特願２００２−１８１７３２、特願２００２−０６６４０５の提案を行なっている。   In addition, as a prior art regarding bending workability improvement, the technique of patent document 1 which controls a compound dispersion state by controlling the cooling rate after an ingot homogenization process, the orientation difference of a crystal grain boundary is 15 degrees or less, or 20 There are Patent Document 2, Patent Document 3, and the like that regulate the proportion of crystal grain boundaries of less than 0 °. The present inventors have already proposed Japanese Patent Applications 2002-181732 and 2002-066645.

特開２００３−１０５４７１JP 2003-105471 A 特開２００３−１７１７２６JP2003-171726 特開２００３−１６６０２９JP 2003-166029 A

前述のような自動車用ボディシート向けの時効性Ａｌ−Ｍｇ−Ｓｉ系合金板についての従来の製造方法により得られた板では、最近の自動車用ボディシートに要求される特性を充分に満足させることは困難であった。   The plate obtained by the conventional manufacturing method for the aging Al-Mg-Si alloy plate for an automobile body sheet as described above sufficiently satisfies the characteristics required for the recent automobile body sheet. Was difficult.

すなわち、最近ではコストの一層の低減や自動車車体の軽量化等のために、自動車用ボディシートについてさらに薄肉化することが強く要求されており、そのため薄肉でも充分な強度が得られるように、一層の高強度化が求められると同時に、成形性、特にヘム曲げ性の改善が強く要求されているが、これらの性能をバランスよく満足させる点について従来の一般的な製造方法によって得られたＡｌ−Ｍｇ−Ｓｉ系合金板では不充分であった。特にヘム曲げ加工は、曲げ内径が１ｍｍ以下の１８０°曲げという過酷な曲げ加工であるため、良好なヘム曲げ性と強度とを両立させることが困難であるという問題があった。   That is, recently, in order to further reduce the cost and reduce the weight of the automobile body, it has been strongly demanded to further reduce the thickness of the body sheet for automobiles, so that even a thin wall can obtain sufficient strength. In addition to the demand for higher strength, improvement in formability, particularly hem bendability, is strongly demanded. Al—obtained by a conventional general production method in terms of satisfying these performances in a balanced manner. An Mg—Si alloy plate was insufficient. In particular, the hem bending process is a severe bending process of 180 ° bending with a bending inner diameter of 1 mm or less, and thus there is a problem that it is difficult to achieve both good hem bendability and strength.

また塗装焼付については、省エネルギおよび生産性の向上、さらには高温に曝されることが好ましくない樹脂等の材料との併用などの点から、従来よりも焼付温度を低温化し、また焼付時間も短時間化する傾向が強まっている。しかしながら従来の一般的な製法により得られた時効性Ａｌ−Ｍｇ−Ｓｉ系合金板の場合、低温・短時間の塗装焼付処理では、塗装焼付時の硬化（焼付硬化）が不足し、塗装焼付後に充分な高強度が得難くなる問題があった。   In addition, with regard to paint baking, the baking temperature is lower than before, and the baking time is also shortened from the standpoints of energy saving, productivity improvement, and combined use with materials such as resins that are not preferably exposed to high temperatures. There is an increasing tendency to shorten the time. However, in the case of an aging Al-Mg-Si alloy plate obtained by a conventional general manufacturing method, the coating baking process at a low temperature and a short time lacks the curing at the time of coating baking (baking hardening), and after coating baking There was a problem that it was difficult to obtain a sufficiently high strength.

ここで、従来の一般的な製法により得られた時効性Ａｌ−Ｍｇ−Ｓｉ系合金板では、塗装焼付後に高強度を得るために焼付硬化性を高めようとすれば、素材の延性と曲げ加工性（特にヘム曲げ性）が低下し、また板製造後に室温に放置した場合に自然時効により硬化が生じやすくなり、そのため成形性、特にヘム曲げ性が阻害されがちとなるという問題が生じている。   Here, in the aging Al-Mg-Si alloy plate obtained by a conventional general manufacturing method, if it is intended to increase the bake hardenability in order to obtain high strength after coating baking, the ductility and bending of the material (Especially hem bendability) decreases, and when it is allowed to stand at room temperature after the plate is manufactured, it tends to be hardened by natural aging, so that the formability, particularly hem bendability, tends to be hindered. .

また前記各特許文献のうち、特許文献１では、化合物分散状態、特にＭｇ_２Ｓｉの粒径と数を規制することにより曲げ加工性などを改善することが提案されているが、その効果は未だ充分ではなかった。 Of each of the above patent documents, Patent Document 1 proposes to improve the bending workability by regulating the compound dispersion state, in particular, the particle diameter and number of Mg ₂ Si, but the effect is still unsatisfactory. It was not enough.

また特許文献２、特許文献３においては、結晶粒間の方位差が１５°以下あるいは２０°以下である結晶粒界の割合を規制することにより曲げ加工性などを改善することが提案されており、確かにこの方法では、曲げ加工性の一定の改善効果が図られるが、本発明者らが実験・検討を重ねた結果、結晶粒間の方位差が１５°以下あるいは２０°以下である結晶粒界の割合が２０％を越えても、圧延板のあらゆる方向の曲げ性がすべて改善されるわけではないことが判明した。例えば、圧延方向に対し平行な方向、あるいは圧延方向に対し直交する方向の曲げ性の改善が図られても、圧延方向に対し４５°をなす方向の曲げ性は改善されず、所謂、曲げ異方性という新たな問題が生じてしまうことが判明した。   In Patent Document 2 and Patent Document 3, it is proposed to improve bending workability by regulating the ratio of crystal grain boundaries in which the orientation difference between crystal grains is 15 ° or less or 20 ° or less. Certainly, in this method, a certain improvement effect of the bending workability can be achieved. However, as a result of repeated experiments and examinations by the present inventors, a crystal whose orientation difference between crystal grains is 15 ° or less or 20 ° or less. It has been found that even if the grain boundary ratio exceeds 20%, the bendability in all directions of the rolled sheet is not improved. For example, even if the bendability in the direction parallel to the rolling direction or the direction perpendicular to the rolling direction is improved, the bendability in the direction of 45 ° with respect to the rolling direction is not improved. It turns out that a new problem of directionality arises.

この発明は以上の事情を背景としてなされたもので、焼付硬化性が優れていて、塗装焼付時における強度上昇が大きく、しかも板製造後の室温での経時的な変化が少なくて、長期間放置した場合でも自然時効による硬化に起因する成形性の低下も少なく、さらには良好な成形加工性、特に良好な曲げ加工性を有すると同時に、曲げ異方性も少ない成形加工用アルミニウム合金板を、量産的規模で確実かつ安定して製造し得る方法を提供することを目的とするものである。   This invention was made against the background described above, has excellent bake hardenability, has a large increase in strength during paint baking, and has little change over time at room temperature after plate production, and is left for a long time. Even when the aluminum alloy plate for forming process with less bending anisotropy at the same time, there is little decrease in formability due to hardening due to natural aging, and also good forming processability, particularly good bending processability, An object of the present invention is to provide a method that can be reliably and stably manufactured on a mass production scale.

前述のような課題を解決するべく本発明者等が種々実験・検討を重ねた結果、Ａｌ−Ｍｇ−Ｓｉ系合金の成分組成を適切に調整するばかりでなく、結晶組織として、特定の方位、特にキューブ方位（立方体方位）の結晶方位密度を高め、しかもそのキューブ方位周辺の結晶方位、特に圧延方向軸（ＲＤ軸）、板面法線軸（ＮＤ軸）を基準に小角度回転させた方位の結晶方位密度を適切に規制して、塑性異方性の指標となるランクフォード値（ｒ値）を適切な範囲内に規制することによって、曲げ加工性、特にヘム曲げ性を向上させ得ると同時に、その異方性を小さくすることができ、また良好な焼付硬化性、室温での経時変化性を得ることができることを見出した。さらには、曲げ加工時に生じる加工硬化、特に圧延方向に対する３方向の加工硬化量の相互間の関係を適切に制御することによって、曲げ異方性をより確実かつ安定して小さくし得ることを見出した。そしてこのような優れた性能を有する成形加工用アルミニウム合金板を量産的規模で安定して製造し得るプロセス条件を見出し、この発明をなすに至ったのである。   As a result of repeating various experiments and studies by the present inventors in order to solve the above-mentioned problems, not only appropriately adjusting the component composition of the Al-Mg-Si-based alloy, but also a specific orientation, In particular, the crystal orientation density of the cube orientation (cube orientation) is increased, and the crystal orientation around the cube orientation, in particular the rolling direction axis (RD axis) and the plate surface normal axis (ND axis) are rotated by a small angle as a reference. By properly regulating the crystal orientation density and regulating the Rankford value (r value), which is an index of plastic anisotropy, within an appropriate range, it is possible to improve bending workability, particularly hem bendability. It has been found that the anisotropy can be reduced, and good bake hardenability and aging at room temperature can be obtained. Furthermore, it has been found that the bending anisotropy can be reduced more reliably and stably by appropriately controlling the work hardening that occurs during bending, particularly the relationship between the work hardening amounts in the three directions relative to the rolling direction. It was. The inventors have found a process condition capable of stably producing an aluminum alloy sheet for forming having such excellent performance on a mass production scale, and have come to make the present invention.

具体的には、請求項１の発明の成形加工用アルミニウム合金板の製造方法は、Ｍｇ０．３〜１．５％、Ｓｉ０．３〜２．０％を含有し、かつＭｎ０．０３〜０．４％、Ｃｒ０．０１〜０．４％、Ｆｅ０．０３〜０．５％、Ｔｉ０．００５〜０．２％、Ｚｎ０．０３〜２．５％のうちから選ばれた１種または２種以上を含有し、さらにＣｕが１％以下に規制され、残部がＡｌおよび不可避的不純物よりなる合金を素材とし、ＤＣ鋳造法によりスラブに鋳造するにあたり、凝固後の冷却過程においてスラブ表面の６００℃から４００℃までの温度降下速度が３０℃／ｍｉｎ以上でかつスラブ厚中央部の６００℃から４００℃までの温度降下速度が５℃／ｍｉｎ以上となるように鋳造し、その後３００〜４５０℃の範囲内の温度に加熱して熱間圧延を開始し、かつその熱間圧延過程において熱間圧延開始板厚から１００ｍｍの中間板厚までの間における材料温度の降下量が１５０℃以内となるように制御するとともに、熱間圧延終了温度を２００〜３３０℃の範囲内に制御し、熱間圧延終了後圧延率３０％で冷間圧延を施した後、４８０℃以上の温度で溶体化処理を行ない、直ちに１００℃／ｍｉｎ以上の平均冷却速度で５０℃以上１５０℃未満の温度域まで冷却し、続いてその温度域内で１時間以上の安定化処理を行ない、これによりキューブ方位密度がランダム結晶方位を有する試料の３０〜２５０倍の範囲内にあり、かつ圧延方向軸ＲＤを基準としてキューブ理想方位を１０°回転させた結晶方位の方位密度が、板面法線軸ＮＤを基準としてキューブ理想方位を１０°回転させた方位の方位密度より高く、さらに０°、９０°耳率が５％以上で、しかも圧延方向と平行な方向のランクフォード値ｒ_０が０．５０〜１．５０の範囲内、板面内において圧延方向に対し４５°をなす方向のランクフォード値ｒ_４５が０．０１〜０．４５の範囲内、板面内において圧延方向に対し直交する方向のランクフォード値ｒ_９０が０．６０〜３．５０の範囲内にあり、さらに導電率が５４％ＩＡＣＳ以下であるアルミニウム合金板を得ることを特徴とするものである。 Specifically, the manufacturing method of the aluminum alloy sheet for forming according to the invention of claim 1 contains Mg 0.3 to 1.5%, Si 0.3 to 2.0%, and Mn 0.03 to 0.00. 1% or more selected from 4%, Cr 0.01-0.4%, Fe 0.03-0.5%, Ti 0.005-0.2%, Zn 0.03-2.5% In addition, Cu is regulated to 1% or less, the remainder is made of an alloy consisting of Al and inevitable impurities, and when cast into a slab by the DC casting method, in the cooling process after solidification, from 600 ° C. on the surface of the slab Casting is performed so that the temperature drop rate to 400 ° C is 30 ° C / min or more and the temperature drop rate from 600 ° C to 400 ° C at the center of the slab thickness is 5 ° C / min or more, and then the range of 300 to 450 ° C. Hot rolling by heating to the temperature inside In the hot rolling process, the material temperature is controlled to fall within 150 ° C. from the hot rolling start plate thickness to the intermediate plate thickness of 100 mm, and the hot rolling end temperature is set to 200 ° C. Control within the range of ˜330 ° C., and after cold rolling at a rolling rate of 30% after completion of hot rolling, solution treatment is performed at a temperature of 480 ° C. or higher, and immediately an average cooling rate of 100 ° C./min or higher. The sample is cooled to a temperature range of 50 ° C. or higher and lower than 150 ° C., followed by stabilization treatment for 1 hour or longer in the temperature range, whereby the cube orientation density is within a range of 30 to 250 times that of a sample having a random crystal orientation. The orientation density of the crystal orientation obtained by rotating the cube ideal orientation by 10 ° with respect to the rolling direction axis RD is the orientation obtained by rotating the cube ideal orientation by 10 ° with respect to the plate normal axis ND. Higher than the orientation density, further 0 °, 90 ° in the ear of between 5% or more, yet within the scope of Lankford values r ₀ of the rolling direction and the direction parallel from 0.50 to 1.50, the rolling direction in the sheet surface The Rankford value r _{45 in the} direction of 45 ° with respect to the range of 0.01 to 0.45, and the Rankford value r ₉₀ in the direction perpendicular to the rolling direction in the plate surface is 0.60 to 3.50. In addition, an aluminum alloy plate having a conductivity of 54% IACS or less is obtained.

また請求項２の発明の成形加工用アルミニウム合金板の製造方法は、請求項１に記載の成形加工用アルミニウム合金板の製造方法において、圧延方向に対し板面内で０°、４５°、９０°の３方向にそれぞれ圧延率８０％の冷間圧延を加えたときに、４５°方向の０．２％耐力値の上昇分が０°方向の０．２％耐力値の上昇分および９０°方向の０．２％耐力値上昇分よりも大きく、かつその４５°方向０．２％耐力値上昇分と、０°方向耐力値上昇分および９０°方向０．２％耐力値上昇分との差がそれぞれ５〜７０ＭＰａの範囲内にあるアルミニウム合金板を得ることを特徴とするものである。   According to a second aspect of the present invention, there is provided a method for producing an aluminum alloy sheet for forming according to the first aspect of the invention, wherein the aluminum alloy sheet for forming is formed at 0 °, 45 °, 90 ° within the plate surface with respect to the rolling direction. When cold rolling with a rolling rate of 80% is applied in each of the three directions of °, the increase in 0.2% proof stress in the 45 ° direction is the increase in 0.2% proof stress in the 0 ° direction and 90 ° Larger than the 0.2% yield strength increase in the direction, and the increase in the 45% direction 0.2% yield strength, the 0 ° direction yield increase and the 90 ° direction 0.2% yield increase An aluminum alloy plate having a difference in the range of 5 to 70 MPa is obtained.

なおこの発明においてキューブ方位密度とは、キューブ理想方位である（１００）＜００１＞方位の結晶方位密度を意味する。すなわち、一般の工業用材料では、上記のキューブ理想方位を中心に１５°まで回転させた範囲内の結晶方位密度をキューブ方位密度と称することが多いが、この発明では上述のようにキューブ理想方位の方位密度と、そのキューブ理想方位の周辺方位の方位密度（圧延方向軸ＲＤを基準としてキューブ理想方位を１０°回転させた結晶方位の方位密度、および板面法線軸ＮＤを基準としてキューブ理想方位を１０°回転させた結晶方位の方位密度）とを明確に区別するため、キューブ理想方位の方位密度をもってキューブ方位密度と称することとしている。   In the present invention, the cube orientation density means a crystal orientation density of (100) <001> orientation which is a cube ideal orientation. That is, in general industrial materials, the crystal orientation density within the range rotated up to 15 ° around the cube ideal orientation is often referred to as cube orientation density. Orientation density and the orientation density of the peripheral orientation of the cube ideal orientation (the orientation density of the crystal orientation obtained by rotating the cube ideal orientation by 10 ° with respect to the rolling direction axis RD and the cube ideal orientation based on the plate normal axis ND) In order to distinguish clearly from the orientation density of the crystal orientation obtained by rotating the angle of 10 °, the orientation density of the cube ideal orientation is referred to as the cube orientation density.

この発明によれば、成形性、特にヘム曲げ性が優れていると同時に、曲げ異方性も少なく、さらには塗装焼付硬化性が良好で塗装焼付後の強度が高く、また室温での経時変化も少ない成形加工用アルミニウム合金板を、量産的規模で確実かつ安定して得ることができる。   According to the present invention, the moldability, particularly hem bendability is excellent, the bending anisotropy is small, the paint bake hardenability is good, the strength after paint bake is high, and the change with time at room temperature. Can be obtained reliably and stably on a mass production scale.

先ずこの発明で製造対象となる成形加工用アルミニウム合金板における成分組成の限定理由について説明する。   First, the reason for limitation of the component composition in the aluminum alloy sheet for forming which is a production target in the present invention will be described.

Ｍｇ：
Ｍｇはこの発明で対象としている系の合金で基本となる合金元素であって、Ｓｉと共同して強度向上に寄与する。Ｍｇ量が０．３％未満では塗装焼付時に析出硬化によって強度向上に寄与するＧ．Ｐ．ゾーンの生成量が少なくなるため、充分な強度向上が得られず、一方１．５％を越えれば、粗大なＭｇ−Ｓｉ系の金属間化合物が生成され、キューブ方位密度を高めるために不利となり、成形性、特に曲げ加工性が低下するから、Ｍｇ量は０．３〜１．５％の範囲内とした。 Mg:
Mg is an alloy element that is a basic alloy of the system targeted by the present invention, and contributes to strength improvement in cooperation with Si. If the amount of Mg is less than 0.3%, G. contributes to strength improvement by precipitation hardening during baking. P. Since the amount of zone formation decreases, sufficient strength improvement cannot be obtained. On the other hand, if it exceeds 1.5%, coarse Mg-Si based intermetallic compounds are generated, which is disadvantageous for increasing cube orientation density. Further, since the formability, particularly the bending workability is lowered, the Mg amount is set in the range of 0.3 to 1.5%.

Ｓｉ：
Ｓｉもこの発明の系の合金で基本となる合金元素であって、Ｍｇと共同して強度向上に寄与する。またＳｉは、鋳造時に金属Ｓｉの晶出物として生成され、その金属Ｓｉ粒子の周囲が加工によって変形されて、溶体化処理の際に再結晶核の生成サイトとなるため、再結晶組織の微細化にも寄与する。Ｓｉ量が０．３％未満では上記の効果が充分に得られず、一方２．０％を越えれば粗大なＳｉ粒子や粗大なＭｇ−Ｓｉ系の金属間化合物が生じてキューブ方位密度を高めるために不利となり、成形性、特に曲げ加工性の低下を招く。したがってＳｉ量は０．３〜２．０％の範囲内とした。 Si:
Si is also an alloy element that is fundamental in the alloy of the present invention, and contributes to strength improvement in cooperation with Mg. In addition, Si is produced as a crystallized product of metal Si at the time of casting, and the periphery of the metal Si particles is deformed by processing and becomes a recrystallization nucleus generation site during solution treatment. It also contributes to If the amount of Si is less than 0.3%, the above effect cannot be obtained sufficiently. On the other hand, if it exceeds 2.0%, coarse Si particles and coarse Mg-Si based intermetallic compounds are generated to increase the cube orientation density. For this reason, it becomes disadvantageous, and the formability, particularly bending workability, is reduced. Therefore, the Si amount is set in the range of 0.3 to 2.0%.

Ｍｎ、Ｃｒ、Ｆｅ、Ｔｉ、Ｚｎ：
これらの元素は、強度向上や結晶粒微細化、あるいは時効性の向上や表面処理性の向上に有効であり、いずれか１種または２種以上を添加する。これらのうちＭｎ、Ｃｒは強度向上と結晶粒の微細化および組織の安定化に効果がある元素であるが、Ｍｎの含有量が０．０３％未満、もしくはＣｒの含有量が０．０１％未満では、上記の効果が充分に得られず、一方Ｍｎ、Ｃｒの含有量がそれぞれ０．４％を越えれば、上記の効果が飽和するばかりでなく、多数の金属間化合物が生成されて成形性、特にヘム曲げ性に悪影響を及ぼすおそれがあり、したがってＭｎは０．０３〜０．４％の範囲内、Ｃｒは０．０１〜０．４％の範囲内とした。またＦｅも強度向上と結晶粒微細化に有効な元素であるが、その含有量が０．０３％未満では充分な効果が得られず、一方０．５％を越えれば、キューブ方位密度を高める上において不利となって、成形性、特に曲げ加工性が低下するおそれがあり、したがってＦｅ量は０．０３〜０．５％の範囲内とした。さらにＴｉも強度向上と鋳塊組織の微細化に有効な元素であるが、その含有量が０．００５％未満では充分な効果が得られず、一方０．２％を越えればＴｉ添加の効果が飽和するばかりでなく、粗大な晶出物が生じるおそれがあるから、Ｔｉ量は０．００５〜０．２％の範囲内とした。またＺｎは時効性向上を通じて強度向上に寄与するとともに表面処理性の向上に有効な元素であるが、Ｚｎの添加量が０．０３％未満では上記の効果が充分に得られず、一方２．５％を越えれば成形性が低下するから、Ｚｎ量は０．０３〜２．５％の範囲内とした。 Mn, Cr, Fe, Ti, Zn:
These elements are effective for improving the strength, refining crystal grains, improving aging properties, and improving surface treatment properties, and any one or more of them are added. Among these, Mn and Cr are elements that are effective in improving the strength, refining crystal grains, and stabilizing the structure. However, the Mn content is less than 0.03%, or the Cr content is 0.01%. If the content is less than 0.4%, the above effects cannot be sufficiently obtained. On the other hand, if the contents of Mn and Cr exceed 0.4%, the above effects are not only saturated, but a large number of intermetallic compounds are formed and formed. Therefore, Mn is in the range of 0.03 to 0.4%, and Cr is in the range of 0.01 to 0.4%. Fe is also an element effective for strength improvement and grain refinement, but if its content is less than 0.03%, sufficient effects cannot be obtained, while if it exceeds 0.5%, the cube orientation density is increased. There is a disadvantage in that the moldability, particularly the bending workability, may be lowered, and therefore the Fe content is set in the range of 0.03 to 0.5%. Furthermore, Ti is an element effective for improving the strength and refining the ingot structure, but if its content is less than 0.005%, a sufficient effect cannot be obtained, while if it exceeds 0.2%, the effect of adding Ti In addition to being saturated, there is a possibility that coarse crystallized matter may be formed, so the Ti content is set in the range of 0.005 to 0.2%. Zn is an element that contributes to improvement of strength through improvement of aging and is effective for improvement of surface treatment. However, if the amount of Zn is less than 0.03%, the above effect cannot be obtained sufficiently. If the content exceeds 5%, the moldability deteriorates, so the Zn content is set in the range of 0.03 to 2.5%.

Ｃｕ：
Ｃｕは強度向上および成形性向上のために添加されることがある元素であるが、その量が１．０％を越えれば耐食性（耐粒界腐食性、耐糸錆性）が劣化するから、Ｃｕの含有量は１．０％以下に規制することとした。なお特に耐食性を重視する場合は、Ｃｕ量は０．０５％以下に規制することが望ましい。 Cu:
Cu is an element that may be added to improve strength and formability, but if its amount exceeds 1.0%, corrosion resistance (intergranular corrosion resistance, yarn rust resistance) deteriorates. The Cu content was regulated to 1.0% or less. In particular, when emphasizing corrosion resistance, it is desirable to limit the amount of Cu to 0.05% or less.

以上の各元素のほかは、基本的にはＡｌおよび不可避的不純物とすれば良い。   In addition to the above elements, basically, Al and inevitable impurities may be used.

なお上記のＭｎ、Ｃｒ、Ｆｅ、Ｔｉ、Ｚｎの含有量範囲は、それぞれ積極的に添加する場合の範囲として示したものであり、いずれも下限値より少ない量を不純物として含有する場合を排除するものではない。特に０．０３％未満のＦｅは、通常のアルミ地金を用いれば不可避的に含有されるのが通常である。   In addition, the above-mentioned content ranges of Mn, Cr, Fe, Ti, and Zn are shown as ranges in the case where each is positively added, and all exclude cases where the content is less than the lower limit as impurities. It is not a thing. In particular, Fe of less than 0.03% is usually inevitably contained if a normal aluminum ingot is used.

また時効性Ａｌ−Ｍｇ−Ｓｉ系合金においては、高温時効促進元素あるいは室温時効抑制元素であるＡｇ、Ｉｎ、Ｃｄ、Ｂｅ、あるいはＳｎを微量添加することがあるが、この発明の場合も微量添加であればこれらの元素の添加も許容され、それぞれ０．３％以下であれば特に所期の目的を損なうことはない。   In addition, in an aging Al—Mg—Si alloy, a trace amount of Ag, In, Cd, Be, or Sn, which is a high temperature aging promoting element or a room temperature aging inhibiting element, may be added. If so, the addition of these elements is allowed, and if the content is 0.3% or less, the intended purpose is not particularly impaired.

なおまた、一般のＡｌ合金においては、結晶粒微細化のために前述のＴｉと同時にＢを添加することもあり、この発明の場合もＴｉとともに５００ｐｐｍ以下のＢを添加することは許容される。   In addition, in a general Al alloy, B may be added simultaneously with the above-mentioned Ti for crystal grain refinement, and in the present invention, addition of 500 ppm or less of B together with Ti is permitted.

さらにこの発明の成形加工用アルミニウム合金板の製造方法において、良好な曲げ加工性、特に良好なヘム曲げ性を得ると同時に、曲げ異方性を小さく抑制するためには、合金の成分組成を前述のように調整するばかりではなく、板の金属組織、特に結晶方位を適切に制御することが極めて重要である。   Furthermore, in the method for producing an aluminum alloy sheet for forming according to the present invention, in order to obtain good bending workability, in particular, good hem bendability, and at the same time to suppress bending anisotropy, the alloy component composition is described above. It is extremely important to appropriately control the metal structure of the plate, particularly the crystal orientation, in addition to the adjustment as described above.

すなわちこの発明において、結晶方位密度を規制しているのは、粒界の性質（小角か大角か）を制御するためだけではなく、アルミニウム合金の塑性変形に伴う結晶のすべり変形全体を制御することを主目的としている。そして特に曲げ加工中に交差すべりが生じやすいような結晶方位の集積度を高めることが極めて重要であり、そのようにすることによって、加工による転位密度の増加を抑えて、加工硬化を抑制することが可能となるのである。さらにその結果、ヘム曲げ加工の際において、加工硬化の抑制により割れ限界強度に達するまで材料の大歪変形が可能となる。ここで、すべり変形挙動を、比較的ランダムな結晶方位を有する従来の材料、言い換えれば比較的交差すべりが生じ難い従来材料と大きく異ならしめるためには、結晶方位の集積が必要である。一方実際の材料では、種々の結晶方位が存在するが、本発明者らが鋭意検討を重ねた結果、種々の結晶方位のうちでも特にキューブ方位の方位密度、すなわちキューブ方位の理想方位である（００１）＜１００＞方位の方位密度を、ランダムな結晶方位を有する試料の方位密度の３０倍から２５０倍までの範囲内に高めることによって、すべり変形挙動を、従来材料とは大きく異ならしめることができることを見出した。すなわち、このようにキューブ方位密度をランダム方位試料の３０〜２５０倍の範囲内とすることによって、加工変形中における交差すべりが活発となり、加工硬化が抑制され、曲げ加工性が改善されるのである。ここで、キューブ方位密度がランダム方位試料の３０倍未満では、上記の効果が不充分であり、一方２５０倍を越えれば、引張強度、伸びなどの異方性が強くなりすぎ、成形性の低下が懸念される。そこでこの発明ではキューブ方位密度をランダム方位試料の３０〜２５０倍の範囲内と規定した。   In other words, in this invention, the crystal orientation density is controlled not only to control the grain boundary properties (small angle or large angle) but also to control the overall slip deformation of the crystal accompanying the plastic deformation of the aluminum alloy. Is the main purpose. In particular, it is extremely important to increase the degree of accumulation of crystal orientations that are likely to cause cross-slip during bending. By doing so, the increase in dislocation density due to processing is suppressed, and work hardening is suppressed. Is possible. As a result, during hem bending, large strain deformation of the material is possible until the crack limit strength is reached by suppressing work hardening. Here, in order to make the slip deformation behavior greatly different from that of a conventional material having a relatively random crystal orientation, in other words, a conventional material that hardly causes cross-slip, it is necessary to accumulate crystal orientations. On the other hand, there are various crystal orientations in the actual material, but as a result of extensive studies by the present inventors, the orientation density of the cube orientation, that is, the ideal orientation of the cube orientation, in particular, among the various crystal orientations ( 001) By increasing the orientation density of the <100> orientation within the range of 30 to 250 times the orientation density of a sample having a random crystal orientation, the slip deformation behavior can be made significantly different from that of conventional materials. I found out that I can do it. That is, by making the cube orientation density in the range of 30 to 250 times that of the random orientation sample in this way, cross-slip during work deformation becomes active, work hardening is suppressed, and bending workability is improved. . Here, when the cube orientation density is less than 30 times that of the random orientation sample, the above effect is insufficient. On the other hand, when the cube orientation density exceeds 250 times, the anisotropy such as tensile strength and elongation becomes too strong, and the moldability deteriorates. Is concerned. Therefore, in the present invention, the cube orientation density is defined within a range of 30 to 250 times that of the random orientation sample.

さらに、単に曲げ加工性を改善するばかりでなく、曲げ加工性の異方性、すなわち曲げ異方性を改善するためには、圧延方向と平行な方向（０°方向）、板面内において圧延方向に対し直交する方向（９０°方向）の曲げ加工性を低下させることなく、特に圧延方向に対して板面内で４５°の方向の曲げ性を向上させることが必要であり、そのためには、キューブ理想方位（００１）＜１００＞から圧延方向軸（ＲＤ軸）を基準として１０°回転させた方位（以下“ＲＤ１０方位”と記す）の方位密度が、同じくキューブ理想方位から板面法線軸（ＮＤ軸）を基準として１０°回転させた方位（以下“ＮＤ１０方位”と記す）の方位密度よりも高いこと、すなわち、
ＲＤ１０方位密度＞ＮＤ１０方位密度
となることが必要である。 Furthermore, in order to improve not only the bending workability but also the anisotropy of the bending workability, that is, the bending anisotropy, rolling is performed in the direction parallel to the rolling direction (0 ° direction) in the plate surface. It is necessary to improve the bendability in the direction of 45 ° in the plate surface with respect to the rolling direction without reducing the bending workability in the direction orthogonal to the direction (90 ° direction). The orientation density of the orientation (hereinafter referred to as “RD10 orientation”) rotated by 10 ° with respect to the rolling direction axis (RD axis) from the ideal cube orientation (001) <100> is the normal axis of the plate surface from the ideal cube orientation. It is higher than the orientation density of the orientation (hereinafter referred to as “ND10 orientation”) rotated by 10 ° with respect to the (ND axis), that is,
It is necessary that RD10 orientation density> ND10 orientation density.

すなわち、既に述べたように一般的に実用的な工業材料においてある結晶方位の方位密度を表わす場合、理想方位に対して１５°回転した方位まで含めてその方位の方位密度と称することが多く、キューブ方位の方位密度の場合も、キューブ理想方位（００１）＜１００＞から１５°までずれる方位を含ませることが多いが、本発明者らはこのようなキューブ理想方位から１５°以内の範囲内でずれた方位について、曲げ性に及ぼす影響を詳細に検討した結果、ＲＤ１０方位密度をＮＤ１０方位密度より高くすることによって、圧延方向と平行な方向（０°方向）、あるいは圧延方向に対し直交する方向（９０°方向）の曲げ性を低下させることなく、圧延方向に対し４５°をなす方向（４５°方向）の曲げ性を改善し得ることを見出し、上記の条件を規定した。   That is, as described above, when representing the orientation density of a crystal orientation in a practical industrial material as described above, it is often referred to as the orientation density of that orientation including the orientation rotated by 15 ° with respect to the ideal orientation. In the case of the orientation density of the cube orientation, an orientation that deviates from the cube ideal orientation (001) <100> to 15 ° is often included, but the present inventors are within a range within 15 ° from such cube ideal orientation. As a result of examining the influence on the bendability in detail for the azimuth misaligned at, the RD10 azimuth density is made higher than the ND10 azimuth density, so that the direction parallel to the rolling direction (0 ° direction) or perpendicular to the rolling direction. It has been found that the bendability in the direction (45 ° direction) that forms 45 ° with respect to the rolling direction can be improved without reducing the bendability in the direction (90 ° direction). Defining the matter.

さらにこの発明による成形加工用アルミニウム合金板では、板全体にわたって０°耳、９０°耳の耳率が５％以上であることも重要である。すなわち、前述のようにこの発明では良好な曲げ加工性を確保しかつ曲げ異方性を抑制するためにキューブ方位密度およびその周辺方位密度（ＲＤ１０方位密度、ＮＤ１０方位密度）を規定しているが、それ以外の結晶方位の方位密度もある程度は曲げ加工性に影響を与える。しかしながら実際上は、これらの方位以外のすべての結晶方位の方位密度を厳密に規定することは困難である。一方、板のカッピング試験で絞ったカップの耳率によれば、材料の結晶方位をマクロ的に評価することができる。そこでこの発明では、キューブ方位やその周辺方位以外の結晶方位の方位密度の影響を、０°耳、９０°耳で評価、規制することとした。具体的には、圧延方向を基準にカップの０°、９０°耳率が５％未満では、たとえ前述のキューブ方位密度およびその周辺方位密度の条件が満足されていても、良好な曲げ加工性、曲げ異方性が得られないおそれがある。そこでこの発明では耳率に関して前述のように規制することとした。なお０°、９０°耳率は、上記の範囲内でも特に１０％以上が望ましい。   Further, in the aluminum alloy plate for forming according to the present invention, it is also important that the ear rate of the 0 ° ear and the 90 ° ear is 5% or more over the entire plate. That is, as described above, the present invention defines the cube orientation density and the peripheral orientation density (RD10 orientation density, ND10 orientation density) in order to ensure good bending workability and suppress bending anisotropy. The orientation density of other crystal orientations also affects the bending workability to some extent. However, in practice, it is difficult to strictly define the orientation density of all crystal orientations other than these orientations. On the other hand, the crystal orientation of the material can be macroscopically evaluated based on the ear ratio of the cup squeezed by the plate cupping test. Therefore, in the present invention, the influence of the orientation density of the crystal orientation other than the cube orientation and the peripheral orientation is evaluated and regulated by 0 ° ear and 90 ° ear. Specifically, when the 0 ° and 90 ° ear ratio of the cup is less than 5% based on the rolling direction, good bending workability is achieved even if the above-mentioned cube orientation density and peripheral orientation density conditions are satisfied. There is a risk that bending anisotropy may not be obtained. Therefore, in the present invention, the ear rate is regulated as described above. The 0 ° and 90 ° ear ratios are particularly preferably 10% or more even within the above range.

そしてまたこの発明の成形加工用アルミニウム合金板の製造方法においては、製品板の３方向のランクフォード値（ｒ値）を規定している。すなわち圧延方向と平行な方向のランクフォード値（以下“ｒ₀”と記す）が０．５０〜１．５０の範囲内、好ましくは０．６５〜１．５０の範囲内、また圧延方向に対し板面内で４５°の角度をなす方向のｒ値（以下“ｒ₄₅”と記す）が０．０１〜０．４５の範囲内、圧延方向に対し板面内で直交する方向のｒ値（以下“ｒ₉₀”と記す）が０．６０〜３．５０の範囲内、好ましくは０．９５〜３．５０の範囲内であることを規定している。このように３方向のｒ値を定めた理由は次の通りである。 In addition, in the method for manufacturing an aluminum alloy plate for forming according to the present invention, the three-direction Rankford value (r value) of the product plate is defined. That is, the Rankford value (hereinafter referred to as “r ₀ ”) in the direction parallel to the rolling direction is in the range of 0.50 to 1.50, preferably in the range of 0.65 to 1.50, and with respect to the rolling direction. The r value in the direction perpendicular to the rolling direction within the range of 0.01 to 0.45 within the r value (hereinafter referred to as “r ₄₅ ”) forming an angle of 45 ° within the plate surface (hereinafter referred to as “r ₄₅ ”). (Hereinafter referred to as “r ₉₀ ”) is in the range of 0.60 to 3.50, preferably in the range of 0.95 to 3.50. The reason why the r values in the three directions are determined in this way is as follows.

既に述べたように曲げ加工性、曲げ異方性は結晶方位密度の影響を強く受けるが、あらゆる結晶方位密度をすべて細かく規定することは現実には極めて困難である。一方、ｒ値は塑性異方性を表わす指標であって、結晶方位と密接な関係があるから、ｒ値を適切な範囲に制御することによって、曲げ加工性、曲げ異方性をより確実に制御することができる。すなわち、３方向のｒ値（ｒ_１０、ｒ_４５、ｒ_９０）が上記の範囲から外れれば、たとえキューブ方位密度条件や周辺方位密度（ＲＤ１０方位密度、ＮＤ１０方位密度）の条件を満足していても、良好な曲げ加工性、曲げ異方性が得られないおそれがある。そこで３方向のｒ値、すなわちｒ_１０、ｒ_４５、ｒ_９０を前述のように規定した。 As described above, bending workability and bending anisotropy are strongly influenced by the crystal orientation density, but it is actually very difficult to finely define all crystal orientation densities. On the other hand, the r value is an indicator of plastic anisotropy and has a close relationship with the crystal orientation. Therefore, by controlling the r value within an appropriate range, bending workability and bending anisotropy can be more reliably achieved. Can be controlled. That is, if the r value (r ₁₀ , r ₄₅ , r ₉₀ ) in the three directions is out of the above range, the cube orientation density condition and the peripheral orientation density (RD10 orientation density, ND10 orientation density) conditions are satisfied. However, good bending workability and bending anisotropy may not be obtained. Therefore, r values in three directions, that is, r ₁₀ , r ₄₅ , and r ₉₀ were defined as described above.

以上の各条件のほか、請求項２の発明の成形加工用アルミニウム合金板の製造方法においては、最終製品板の３方向、すなわち圧延方向と平行な方向（０°方向）、板面内において圧延方向に対し直交する方向（９０°方向）、板面内において圧延方向に対し４５°の角度をなす方向（４５°方向）に、それぞれ圧延率８０％の冷間圧延を加えたときの加工硬化による各方向の０．２％耐力値の上昇分（冷間圧延前の０．２％耐力値に対する冷間圧延後の０．２％耐力値の増加分）を規定している。すなわち、４５°方向の耐力値上昇分Δσ_４５が、０°方向の耐力値上昇分Δσ_０および９０°方向の耐力値上昇分Δσ_９０と比べて大きく、しかも４５°方向耐力値上昇分Δσ_４５と９０°方向耐力値上昇分Δσ_９０との差および４５°方向耐力値上昇分Δσ_４５と０°方向耐力値上昇分Δσ_０との差が、いずれも５〜７０ＭＰａの範囲内にあることを規定している。 In addition to the above conditions, in the method for manufacturing an aluminum alloy plate for forming according to the invention of claim 2, rolling is performed in three directions of the final product plate, that is, in a direction parallel to the rolling direction (0 ° direction) and in the plate surface. Work hardening when cold rolling with a rolling rate of 80% is applied in a direction perpendicular to the direction (90 ° direction) and in a direction (45 ° direction) forming an angle of 45 ° with respect to the rolling direction in the plate surface. Is defined as an increase in 0.2% proof stress value in each direction (increase in 0.2% proof stress value after cold rolling relative to 0.2% proof stress value before cold rolling). That is, the 45 ° direction yield value increase Δσ ₄₅ is larger than the 0 ° direction yield value increase Δσ ₀ and the 90 ° direction yield value increase Δσ ₉₀ , and the 45 ° direction yield value increase Δσ _45. And 90 ° direction yield strength increase Δσ ₉₀ and 45 ° direction yield value increase Δσ ₄₅ and 0 ° direction yield value increase Δσ ₀ are both in the range of 5 to 70 MPa. It stipulates.

換言すれば、次の４式、
Δσ_４５＞Δσ_０
Δσ_４５＞Δσ_９０
７０ＭＰａ≧Δσ_４５−Δσ_０≧５ＭＰａ
７０ＭＰａ≧Δσ_４５−Δσ_９０≧５ＭＰａ
を満たすことを規定している。 In other words, the following four formulas:
Δσ ₄₅ > Δσ ₀
Δσ ₄₅ > Δσ ₉₀
70 MPa ≧ Δσ ₄₅ −Δσ ₀ ≧ 5 MPa
70 MPa ≧ Δσ ₄₅ −Δσ ₉₀ ≧ 5 MPa
It stipulates that

このような３方向の加工硬化の条件を請求項２において規定した理由は次の通りである。   The reason why the conditions for such work hardening in three directions are defined in claim 2 is as follows.

材料の加工硬化性は、曲げ加工性を支配する重要な因子であり、一般的に材料の加工硬化性には、材料の化学成分、溶質濃度、分散粒子、加工度が大きな影響を及ぼすことが知られているが、本発明者らはそれら以外に集合組織（結晶方位）との関係を詳細に検討した結果、結晶方位の集積度が高ければ、加工硬化の異方性も顕著に表れることを突き止めめ、これが最終的に曲げ加工の異方性に反映されることを見出した。すなわち、材料のキューブ方位密度が高くなるにつれて、既に述べたように圧延方向と平行な方向あるいは圧延方向に対し直交する方向の曲げ加工性は著しく改善されるが、その反面、圧延方向に対し４５°をなす方向の曲げ加工性の改善度合いは、他の２方向と比べて小さくなり、曲げ加工性の異方性は大きくなってしまう。そこでこの発明では、キューブ理想方位の周辺方位であるＲＤ１０方位密度とＮＤ１０方位密度を、ＲＤ１０方位密度＞ＮＤ１０方位密度の関係を満たすよう規制することが曲げ異方性の改善に有効であることを見出し、この条件を請求項１において規定している。しかるに、実際にはＲＤ１０方位密度、ＮＤ１０方位密度以外の結晶方位の方位密度も曲げ異方性にある程度影響を与える。しかしながら、あらゆる方位密度をすべて細かく規定することは現実には極めて困難であり、そこでトータル的な曲げ異方性の評価として、４５°方向と、０°方向、９０°方向の加工硬化の度合を相対的に規制することによって、曲げ異方性が確実かつ安定して小さい材料が得られるようにした。   The work hardenability of a material is an important factor governing the bending workability. In general, the chemical composition of a material, the solute concentration, dispersed particles, and the degree of processing greatly influence the work hardenability of a material. Although it is known, the present inventors examined the relationship with the texture (crystal orientation) in addition to them, and as a result, if the degree of integration of crystal orientation is high, the anisotropy of work hardening also appears remarkably. And finally found that this is reflected in the anisotropy of bending. That is, as the cube orientation density of the material becomes higher, the bending workability in the direction parallel to the rolling direction or the direction perpendicular to the rolling direction is remarkably improved as described above. The degree of improvement in the bending workability in the direction forming the angle is smaller than in the other two directions, and the anisotropy of the bending workability is increased. Therefore, in the present invention, it is effective to improve the bending anisotropy to regulate the RD10 orientation density and the ND10 orientation density, which are peripheral orientations of the cube ideal orientation, so as to satisfy the relationship of RD10 orientation density> ND10 orientation density. The headline, this condition is defined in claim 1. However, in practice, the orientation density of crystal orientations other than the RD10 orientation density and the ND10 orientation density also affects the bending anisotropy to some extent. However, it is extremely difficult to define all orientation densities finely in reality. Therefore, as an evaluation of total bending anisotropy, the degree of work hardening in 45 ° direction, 0 ° direction and 90 ° direction is determined. By relatively restricting, a material having a small and stable bending anisotropy can be obtained.

ここで、圧延率８０％の冷間圧延を加えたときに、４５°方向の耐力値上昇分Δσ_４５が、０°、９０°方向の耐力値上昇分Δσ_０、Δσ_９０と比べてその差が５ＭＰａ未満では、従来材と比べて全方向曲げ加工性の改善度合いが低い。一方その差が７０ＭＰａを越えれば、０°方向および９０°方向の曲げ加工性は著しく改善されるが、４５°方向の曲げ加工性の改善度合いが極端に小さくなる。したがって板全体の曲げ加工バランスを考慮して、その差を５〜７０ＭＰａの範囲内に規制することとした。 Here, when cold rolling with a rolling rate of 80% is applied, the increase in yield strength value Δσ ₄₅ in the 45 ° direction is different from the increase in yield strength values Δσ ₀ and Δσ _{90 in} the 0 ° and 90 ° directions. If it is less than 5 MPa, the improvement degree of omnidirectional bending workability is low compared with the conventional material. On the other hand, if the difference exceeds 70 MPa, the bending workability in the 0 ° direction and the 90 ° direction is remarkably improved, but the improvement degree of the bending workability in the 45 ° direction becomes extremely small. Therefore, in consideration of the bending balance of the entire plate, the difference is regulated within the range of 5 to 70 MPa.

また以上のほか、この発明による成形加工用アルミニウム合金板では、導電率が５４％ＩＡＣＳ以下であることも必要である。すなわち、導電率は固溶元素の固溶量の指標となり、したがって導電率は焼付硬化性に影響を与える。ここで導電率が５４％ＩＡＣＳを越えれば、固溶しているＭｇとＳｉの量が少なくないため、時効析出硬化量が充分に得られず、塗装焼付後に充分な高強度が得難くなるから、導電率が５４％ＩＡＣＳ以下であることを規定した。なお導電率の下限は特に規制しないが、通常この系の合金では、導電率を４０％ＩＡＣＳ以下としても、塗装焼付硬化性の効果が飽和し、また工業的にこれを実現するには困難となる。   In addition to the above, the aluminum alloy sheet for forming according to the present invention is required to have a conductivity of 54% IACS or less. That is, the conductivity is an indicator of the solid solution amount of the solid solution element, and therefore the conductivity affects the bake hardenability. Here, if the electrical conductivity exceeds 54% IACS, the amount of Mg and Si dissolved is not small, so that a sufficient amount of aging precipitation hardening cannot be obtained, and it is difficult to obtain a sufficiently high strength after baking. The electrical conductivity is specified to be 54% IACS or less. The lower limit of the electrical conductivity is not particularly limited, but usually in this type of alloy, even if the electrical conductivity is 40% IACS or less, the effect of paint bake hardenability is saturated, and it is difficult to achieve this industrially. Become.

次にこの発明の成形加工用アルミニウム合金板を製造するプロセスについて説明する。   Next, a process for producing the aluminum alloy plate for forming according to the present invention will be described.

先ず前述のような成分組成の合金を常法に従って溶製し、ＤＣ鋳造法によってスラブに鋳造する。この鋳造時においては、スラブの凝固後、６００℃から４００℃までのスラブ表面の温度降下速度が３０℃／ｍｉｎ以上、６００℃から４００℃までのスラブの厚み方向中央部（スラブ厚中央部）の温度降下速度が５℃／ｍｉｎ以上に維持されるように鋳造する。このような凝固後の条件を適用することにより、鋳造したスラブのままの状態でＭｇ、Ｓｉ等の元素を充分に固溶させることができ、その結果、従来の一般的な製造方法で適用されている鋳塊均質化処理を行なわなくても、最終製品板の段階で充分な塗装焼付硬化性を確保することが可能となる。そしてまたこのように均質化処理を行なわなかったスラブは、均質化処理を行なったスラブとは第２相粒子の分布状態が異なり、その後の熱間圧延以降の工程条件としてこの発明で規定している条件を適用することによって、最終的に前述の集合組織条件を満たす製品板を容易かつ確実に得ることができる。また均質化処理を省くことによって、製造コストの面でも有利となることはもちろんである。   First, an alloy having the above component composition is melted in accordance with a conventional method, and cast into a slab by a DC casting method. At the time of casting, after the slab is solidified, the temperature drop rate on the surface of the slab from 600 ° C. to 400 ° C. is 30 ° C./min or more, and the center portion in the thickness direction of the slab from 600 ° C. to 400 ° C. Is cast so that the temperature drop rate is maintained at 5 ° C./min or more. By applying such post-solidification conditions, elements such as Mg and Si can be sufficiently dissolved in the state of the cast slab, and as a result, the conventional general manufacturing method can be applied. Even without performing the ingot homogenization process, it is possible to ensure sufficient bake hardenability at the final product plate stage. In addition, the slab that has not been subjected to the homogenization process is different from the slab that has been subjected to the homogenization process in the distribution state of the second phase particles, and is defined in the present invention as process conditions after the subsequent hot rolling. By applying these conditions, it is possible to easily and reliably obtain a product plate that finally satisfies the texture condition described above. Of course, omitting the homogenization treatment is advantageous in terms of manufacturing cost.

鋳造−凝固後には、上述のように均質化処理を施すことなく、必要に応じて面削してから熱間圧延を行なう。この熱間圧延は、面削後のスラブを、３００〜４５０℃の範囲に加熱（加熱速度は特に規制しないが、２℃／ｈ以上が好ましい）して保持なし、あるいは２４ｈ以内に保持してから行なうことが望ましい。ここで、熱間圧延前の加熱温度（熱間圧延開始温度）が３００℃未満では熱間圧延が困難となり、一方４５０℃を越える高温に加熱して熱間圧延を開始すれば、最終製品板にリジングマークが発生して外観を損ないやすい。   After casting and solidification, hot rolling is performed after chamfering as necessary without performing homogenization as described above. In this hot rolling, the slab after chamfering is heated to a temperature in the range of 300 to 450 ° C. (the heating speed is not particularly limited, but preferably 2 ° C./h or more) and is not held or held within 24 h. It is desirable to start from. Here, if the heating temperature before hot rolling (hot rolling start temperature) is less than 300 ° C., hot rolling becomes difficult. On the other hand, if hot rolling is started by heating to a high temperature exceeding 450 ° C., the final product plate Ridging marks are generated on the surface and the appearance is liable to be damaged.

さらに熱間圧延過程では、熱間圧延開始時のスラブ厚（通常は面削後の状態で２５０ｍｍ以上）から熱延中間板厚１００ｍｍまでの温度降下量が１５０℃以内となるように制御し、さらに熱延終了温度が２００〜３３０℃となるように制御する。熱間圧延過程においてこれらの条件を適用することは、所要の結晶方位の組織を得るために重要であり、特にＲＤ１０方位密度＞ＮＤ１０方位密度の条件を満たす組織を得るために重要である。これらの条件を外れれば、請求項１で規定する方位密度条件が満たされなくなるおそれがある。   Furthermore, in the hot rolling process, the temperature drop from the slab thickness at the start of hot rolling (usually 250 mm or more in the state after chamfering) to the hot rolled intermediate plate thickness of 100 mm is controlled to be within 150 ° C., Further, the hot rolling end temperature is controlled to be 200 to 330 ° C. Applying these conditions in the hot rolling process is important for obtaining a structure having a desired crystal orientation, and particularly important for obtaining a structure satisfying the condition of RD10 orientation density> ND10 orientation density. If these conditions are not met, the orientation density condition defined in claim 1 may not be satisfied.

上述のようにして熱間圧延を行なってコイルに巻取った後には、中間焼鈍を行なわずに圧延率３０％以上で冷間圧延を施して所要の板厚（製品板厚）とする。このように３０％以上の圧延率で冷間圧延することにより、既に述べたような結晶方位密度条件を有する製品板を得ることができる。またここで、冷間圧延率を３０％以上にすることによって、材料に高い歪みエネルギーが蓄積され、熱間圧延後の溶体化処理−焼入れ時に形成された結晶粒が細かくなって、成形加工後に良好な表面外観品質を得ることが可能となる。冷間圧延率が３０％未満では、成形時に肌荒れ等の表面欠陥が発生するおそれがある。   After hot rolling as described above and winding the coil, cold rolling is performed at a rolling rate of 30% or more without intermediate annealing to obtain a required thickness (product thickness). Thus, by cold rolling at a rolling rate of 30% or more, a product plate having the crystal orientation density conditions as described above can be obtained. Further, here, by setting the cold rolling rate to 30% or more, high strain energy is accumulated in the material, and the crystal grains formed during solution treatment and quenching after hot rolling become finer, after forming processing. Good surface appearance quality can be obtained. If the cold rolling rate is less than 30%, surface defects such as rough skin may occur during molding.

上述のようにして所要の製品板厚とした後には、４８０℃以上の温度で溶体化処理を行なう。この溶体化処理は、Ｍｇ_２Ｓｉ、単体Ｓｉ等をマトリックスに固溶させ、これにより焼付硬化性を付与して塗装焼付後の強度向上を図るために重要な工程である。またこの工程は、Ｍｇ_２Ｓｉ、単体Ｓｉ粒子等の固溶により第二相粒子の分布密度を低下させて、延性と曲げ性を向上させるためにも寄与し、さらには再結晶により最終的に所要の結晶方位を得て、良好な成形性を得るためにも重要な工程である。 After the required product thickness is obtained as described above, solution treatment is performed at a temperature of 480 ° C. or higher. This solution treatment is an important step for solid-dissolving Mg ₂ Si, simple substance Si, etc. in the matrix, thereby imparting bake hardenability and improving the strength after paint baking. This process also contributes to lowering the distribution density of the second phase particles by solid solution of Mg ₂ Si, simple substance Si particles, etc., improving ductility and bendability, and finally by recrystallization. This is an important process for obtaining a desired crystal orientation and obtaining good moldability.

溶体化処理温度が４８０℃未満の場合、室温での経時変化の抑制に対しては有利と考えられるが、その場合Ｍｇ_２Ｓｉ、Ｓｉなどの固溶量が少なくなって、充分な焼付硬化性が得られなくなるばかりでなく、延性と曲げ性も著しく悪化するから、溶体化処理温度は４８０℃以上とする必要がある。一方溶体化処理温度の上限は特に規定しないが、共晶融解の発生のおそれや再結晶粒粗大化等を考慮して、通常は５８０℃以下とすることが望ましい。また溶体化処理の時間は特に規制しないが、通常は５分を越えれば溶体化効果が飽和し、経済性を損なうばかりではなく、結晶粒の粗大化のおそれもあるから、溶体化処理の時間は５分以内が望ましい。 When the solution treatment temperature is less than 480 ° C., it is considered advantageous for suppressing the change over time at room temperature, but in that case, the amount of solid solution of Mg ₂ Si, Si, etc. is reduced and sufficient bake hardenability is obtained. Not only cannot be obtained, but also ductility and bendability are significantly deteriorated. Therefore, the solution treatment temperature must be 480 ° C. or higher. On the other hand, the upper limit of the solution treatment temperature is not particularly specified, but it is usually preferably 580 ° C. or less in consideration of the possibility of eutectic melting and coarsening of recrystallized grains. The solution treatment time is not particularly limited. However, if it exceeds 5 minutes, the solution effect is saturated, not only the economic efficiency is impaired, but also the crystal grains may be coarsened. Is preferably within 5 minutes.

溶体化処理後には、１００℃／ｍｉｎ以上の冷却速度で、５０℃以上１５０℃未満の温度域まで冷却（焼入れ）する。ここで、溶体化処理後の冷却速度が１００℃／ｍｉｎ未満では、冷却中にＭｇ_２Ｓｉあるいは単体Ｓｉが粒界に多量に析出してしまい、成形性、特にヘム曲げ性が低下すると同時に、焼付硬化性が低下して塗装焼付時の充分な強度向上が望めなくなる。 After the solution treatment, it is cooled (quenched) to a temperature range of 50 ° C. or higher and lower than 150 ° C. at a cooling rate of 100 ° C./min or higher. Here, if the cooling rate after the solution treatment is less than 100 ° C./min, Mg ₂ Si or simple substance Si precipitates in the grain boundary during cooling, and at the same time, the formability, particularly the hem bendability decreases, The bake hardenability is lowered, and a sufficient strength improvement at the time of baking is not expected.

上述のように４８０℃以上の温度での溶体化処理を行なって１００℃／ｍｉｎ以上の冷却速度で５０℃以上１５０℃未満の温度域内まで冷却（焼入れ）した後には、５０℃未満の温度域（室温）まで温度降下しないうちに、この温度範囲内（５０〜１５０℃未満）で２時間以上の安定化処理を行なう。この安定化処理は、５０〜１５０℃未満の温度範囲内の一定温度で１時間以上保持しても、あるいはその温度範囲内で１時間以上かけて冷却（徐冷）しても良い。   After performing solution treatment at a temperature of 480 ° C. or higher as described above and cooling (quenching) to a temperature range of 50 ° C. or higher and lower than 150 ° C. at a cooling rate of 100 ° C./min or higher, a temperature range of less than 50 ° C. Before the temperature drops to (room temperature), stabilization treatment is performed for 2 hours or longer within this temperature range (less than 50 to 150 ° C.). This stabilization treatment may be held at a constant temperature within a temperature range of 50 to 150 ° C. for 1 hour or longer, or may be cooled (slowly cooled) over 1 hour within the temperature range.

このように溶体化処理して５０〜１５０℃未満の温度域に焼入れた後、５０℃未満の温度域まで冷却することなくそのまま５０〜１５０℃未満の温度で安定化処理を行なう理由は次の通りである。すなわち、溶体化処理後、特に１００℃／ｍｉｎ以上の平均冷却速度で５０℃未満の室温に冷却した場合には、室温クラスターが生成される。この室温クラスターは強度に寄与するＧ．Ｐ．ゾーンに移行しにくいため、塗装焼付硬化性に不利となる。一方、溶体化処理後に１５０℃以上の温度範囲に冷却してそのまま保持した場合には、Ｇ．Ｐ．ゾーンあるいは安定相が生成され、成形前の素材強度が高くなり過ぎて、ヘム曲げ性とその他の成形性が劣化する。したがってヘム曲げ性、成形性と塗装焼付硬化性とのバランスの観点からは、溶体化処理−焼入れ−安定化処理が上記の条件を満たすことが好ましい。   The reason for performing the stabilization treatment at a temperature of 50 to less than 150 ° C. without cooling to a temperature range of less than 50 ° C. after the solution treatment and quenching to a temperature range of less than 50 to 150 ° C. is as follows. Street. That is, after solution treatment, a room temperature cluster is generated particularly when cooling to room temperature below 50 ° C. at an average cooling rate of 100 ° C./min or more. This room temperature cluster contributes to strength. P. Since it is difficult to shift to the zone, it is disadvantageous for paint bake hardenability. On the other hand, when the solution is cooled to a temperature range of 150 ° C. or higher and kept as it is after the solution treatment, P. Zones or stable phases are generated, the strength of the material before molding becomes too high, and hem bendability and other moldability deteriorate. Therefore, from the viewpoint of the balance between hem bendability, moldability, and paint bake hardenability, it is preferable that the solution treatment-quenching-stabilization treatment satisfies the above conditions.

表１に示すこの発明成分組成範囲内の合金記号Ａ１〜Ａ５の合金について、それぞれ常法に従って溶製し、ＤＣ鋳造法によりスラブに鋳造した。   Alloys of alloy symbols A1 to A5 within the composition range of the present invention shown in Table 1 were melted in accordance with conventional methods and cast into slabs by DC casting.

この鋳造過程においては、凝固終了後、スラブ表面およびスラブ厚中央部の６００℃から４００℃までの温度降下速度が表２中に示すように種々の値となるように制御した。鋳造後、面削してから、熱間圧延前加熱として、２℃／ｈｒ以上の加熱速度で種々の温度に加熱して、その温度で熱間圧延を開始した。なお本発明例としては、スラブ面削後、熱間圧延前には均質化処理を行なわず、比較例の一部としては均質化処理を行なった。熱間圧延過程では、スラブ厚（面削後の厚みで２５０ｍｍ以上）から熱延中間板厚１００ｍｍまでの温度降下量を制御し、さらに熱延終了温度を制御して、コイルに巻取った。その後、冷間圧延途中に中間焼鈍を施すことなく、圧延率６７％で１ｍｍの板厚まで冷間圧延し、さらに種々の温度、時間で溶体化処理を行ない、１００℃／ｍｉｎ以上の冷却速度で種々の温度まで冷却（焼入れ）して、引き続き種々の安定化処理を行なった。これらの製造プロセスの詳細な条件を表２の製造番号１〜９に示す。   In this casting process, after completion of solidification, the temperature drop rate from 600 ° C. to 400 ° C. on the slab surface and the slab thickness center was controlled to have various values as shown in Table 2. After casting, after chamfering, as heating before hot rolling, it was heated to various temperatures at a heating rate of 2 ° C./hr or more, and hot rolling was started at that temperature. As an example of the present invention, the homogenization treatment was not performed before slab chamfering and before hot rolling, and the homogenization treatment was performed as a part of the comparative example. In the hot rolling process, the amount of temperature drop from the slab thickness (250 mm or more after chamfering) to the hot rolled intermediate plate thickness of 100 mm was controlled, and the hot rolling end temperature was controlled to wind the coil. Then, without intermediate annealing during the cold rolling, cold rolling to a sheet thickness of 1 mm at a rolling rate of 67%, further solution treatment at various temperatures and time, cooling rate of 100 ° C./min or more Then, it was cooled (quenched) to various temperatures and subsequently subjected to various stabilization treatments. Detailed conditions of these production processes are shown in production numbers 1 to 9 in Table 2.

なお表２において、製造番号１〜３，８，９は、安定化処理を一定温度保持で行なったもの、また製造番号４〜７は、安定化処理として、一定温度の保持を行なう代りに８０℃から６０℃までの間を冷却速度３〜１０℃／ｈの範囲で徐冷したものである。   In Table 2, production numbers 1 to 3, 8, and 9 are those in which the stabilization process is performed at a constant temperature, and production numbers 4 to 7 are 80 instead of holding a constant temperature as the stabilization process. The temperature is gradually cooled between 0 ° C. and 60 ° C. at a cooling rate of 3 to 10 ° C./h.

以上のようにして得られた各板について、室温に１ヶ月放置したのち、それぞれ２％ストレッチ後、１７０℃×２０分の塗装焼付（ベーク）処理を施し、かつその焼付前の板について引張試験を行なって、圧延方向（ＲＤ）に対し、０°、４５°、９０°の３方向のランクフォード値（ｒ値）を調べるとともに、３方向の０．２％耐力値を測定した。また同じく焼付前の板について、集合組織（結晶方位密度）を調べ、さらにカップ絞り試験による耳率と、導電率を調べるとともに、ヘム曲げ試験によるヘム曲げ加工性評価と、ポンチ張出し試験によるリジングマーク発生評価を行なった。また塗装焼付後の板についても、引張試験を行なって、３方向の０．２％耐力を調べた。さらに、焼付前の板について、３方向それぞれの方向に圧延率８０％の冷間圧延を施して、３方向の耐力値上昇分を測定した。これらの結果を表３および表４に示す。   Each plate obtained as described above was left at room temperature for 1 month, and after 2% stretching, each was subjected to a baking process (baking) at 170 ° C. for 20 minutes, and the plate before the baking was subjected to a tensile test. Then, the rankford value (r value) in three directions of 0 °, 45 °, and 90 ° with respect to the rolling direction (RD) was examined, and the 0.2% proof stress value in three directions was measured. Similarly, the texture (crystal orientation density) of the plate before baking was examined, and the ear rate and conductivity were examined by a cup drawing test. Hem bending workability evaluation by a hem bending test and ridging marks by a punch overhang test were also conducted. Development evaluation was performed. In addition, the plate after coating baking was also subjected to a tensile test to examine 0.2% proof stress in three directions. Further, the plate before baking was subjected to cold rolling at a rolling rate of 80% in each of the three directions, and the increase in the proof stress value in the three directions was measured. These results are shown in Tables 3 and 4.

各測定、試験の具体的手法を次に示す。   Specific methods for each measurement and test are shown below.

引張試験（ｒ値、耐力）：
板の圧延方向に対し板面内０°、４５°、９０°の３方向にＪＩＳ５号引張試験片を採取し、それぞれについて引張試験に供した。そして各方向の０．２％耐力値を調べるとともに、ランクフォード値（ｒ値）として、各方向とも伸びが７．５％となるときのｒ値を求めた。 Tensile test (r value, yield strength):
JIS No. 5 tensile test pieces were sampled in three directions of 0 °, 45 °, and 90 ° in the plate surface with respect to the rolling direction of the plate, and each was subjected to a tensile test. Then, the 0.2% yield strength value in each direction was examined, and the r value when the elongation was 7.5% in each direction was determined as the Rankford value (r value).

集合組織（結晶方位密度）の測定：
厚さ１ｍｍの板について、１０％ＮａＯＨ水溶液で表面から板厚中央に向けて１００μｍずつエッチングしたものを測定サンプルとした。そして表面から板厚方向にそれぞれ１００μｍ、２００μｍ、３００μｍの各位置でそれぞれ測定したキューブ方位密度の平均値を求めた。測定装置としては、リガク（株）のＸ線回折装置を用い、Ｘ線回折のシェルツ反射法により、｛２００｝、｛２２０｝、｛１１１｝の不完全極点図を測定し、これらを元に三次元結晶方位解析（ＯＤＦ）を行なって調べた。またこれらの解析においては、アルミニウム粉末から作られたランダム結晶方位を有する試料を測定して得たデータを｛２００｝、｛２２０｝、｛１１１｝極点図の解析の際に使う規格化ファイルとし、これによりランダム方位を有する試料に対する倍数としてキューブ方位密度を求めた。なおこの発明において、結晶方位密度は全て三次元結晶方位解析（ＯＤＦ）に基づくものである。なおまた、キューブ方位密度は、理想方位である｛１００｝＜００１＞方位の方位密度を求めた。またキューブ理想方位の周辺方位密度として、ＲＤ１０方位密度およびＮＤ１０方位密度を測定した。ここでＲＤ１０方位密度、ＮＤ１０方位密度は、それぞれキューブ理想方位からＲＤ軸で１０°、ＮＤ軸で１０°回転した方位を示す。 Measurement of texture (crystal orientation density):
A 1 mm thick plate etched with 100% by 10% NaOH solution from the surface toward the center of the plate thickness was used as a measurement sample. And the average value of the cube orientation density measured at each position of 100 μm, 200 μm, and 300 μm in the plate thickness direction from the surface was obtained. As a measuring device, an incomplete pole figure of {200}, {220}, {111} is measured by the X-ray diffraction Schertz reflection method using the Rigaku Corporation X-ray diffractometer. A three-dimensional crystal orientation analysis (ODF) was performed and examined. In these analyses, data obtained by measuring a sample having a random crystal orientation made from aluminum powder is used as a standardized file used in the analysis of {200}, {220}, {111} pole figures. Thus, the cube orientation density was determined as a multiple of the sample having a random orientation. In this invention, the crystal orientation density is all based on three-dimensional crystal orientation analysis (ODF). The cube orientation density was determined as the orientation density of {100} <001> orientation, which is an ideal orientation. Further, the RD10 orientation density and the ND10 orientation density were measured as the peripheral orientation density of the cube ideal orientation. Here, the RD10 azimuth density and the ND10 azimuth density indicate azimuths rotated by 10 ° on the RD axis and 10 ° on the ND axis, respectively, from the cube ideal orientation.

耳率：
板に潤滑油を塗布した後、ポンチ径φ３２ｍｍ、ブランク径φ６２ｍｍ、しわ押さえ２００ｋｇの条件でカップに絞り、そのカップの耳率を調べた。なおここで耳率の方向は、圧延方向を基準にした０°方向、９０°方向で示す
導電率（％ＩＡＣＳ）：
渦電流式導電率測定装置を用いて銅、黄銅を基準試料として測定を行なった。 Ear rate:
After applying lubricating oil to the plate, the cup was squeezed under the conditions of a punch diameter of 32 mm, a blank diameter of 62 mm, and a wrinkle holding force of 200 kg, and the ear rate of the cup was examined. Here, the direction of the ear ratio is 0 ° direction and 90 ° direction based on the rolling direction. Conductivity (% IACS):
Measurements were made using copper and brass as a reference sample using an eddy current conductivity measuring device.

加工硬化性（８０％冷間加工後の耐力上昇分）：
板の圧延方向に対し０°方向、４５°方向、９０°方向の各方向に沿って試験片を採取して、それぞれの方向に８０％の冷間圧延を加えた後、その試験片冷間圧延方向に引張試験片を切出して、それぞれ０．２％耐力値の上昇分を調べ、これにより各方向の加工硬化性を評価した。ちなみに耐力値上昇分＝（８０％冷間加工後の耐力値）−（冷間加工前の耐力値）である。 Work hardening (increased yield strength after 80% cold working):
Specimens are taken along the 0 °, 45 °, and 90 ° directions with respect to the rolling direction of the plate, and after 80% cold rolling is applied in each direction, the test piece is cold Tensile test pieces were cut out in the rolling direction, and the increase in 0.2% proof stress value was examined for each, thereby evaluating the work hardenability in each direction. Incidentally, the increase in the proof stress value = (the proof stress value after 80% cold working) − (the proof stress value before cold working).

ヘム加工性の評価：
材料の圧延方向に対して板面内０°、４５°、９０°三方向に曲げ試験片を採取し、１０％ストレッチしてから、１８０°に密着曲げを行ない、目視により割れの発生の有無を観察した。ここで○印は割れ無しを、また×印は割れ有りを示す。 Hem processability evaluation:
Bending specimens are collected in three directions of 0 °, 45 °, and 90 ° in the plate surface with respect to the rolling direction of the material, stretched 10%, then tightly bent at 180 ° and visually checked for cracks. Was observed. Here, a circle indicates that there is no crack, and a cross indicates that there is a crack.

リジング・マークの発生評価：
直径１００ｍｍの球頭ポンチで高さ３０ｍｍまで張出成形を行ない、表面に形成される圧延方向に沿う筋（凹凸）を目視で判定した。○印は筋なしあるいは筋が弱い状態を示し、×印は筋が強い状態を示す。ここで筋が強ければ、自動車用外板の外観として不適当となる。 Evaluation of generation of ridging marks:
Overhanging was performed up to a height of 30 mm with a spherical head punch having a diameter of 100 mm, and the streaks (unevenness) along the rolling direction formed on the surface were visually determined. A circle indicates no muscle or a weak muscle, and a cross indicates a strong muscle. If the streak is strong here, the appearance of the automobile outer plate is inappropriate.

製造番号１〜５は、いずれも合金の成分組成がこの発明で規定する範囲内で製造プロセス条件もこの発明で規定する範囲内であって、最終板の結晶方位密度条件等もすべてこの発明で規定する条件を満たしたものであるが、これらの場合は、ヘム加工性が優れ、また焼付硬化性が高く、塗装焼付時に充分な焼付硬化性を示した。   Production Nos. 1 to 5 are all within the range defined by the present invention in the composition of the alloy, and the production process conditions within the range defined by the present invention. In these cases, the hem processability was excellent and the bake hardenability was high, and a sufficient bake hardenability was exhibited during paint baking.

これに対し製造番号６〜９は、合金の成分組成はこの発明で規定する範囲内であるが、製造プロセス条件のいずれかがこの発明の範囲外であって、結晶方位密度条件等のいずれかがこの発明で規定する条件を満たさなかったものである。これらのうち、製造番号６の場合はヘム曲げ性が劣り、製造番号７の場合はヘム曲げ性とリジング性が劣り、また製造番号８の場合は４５°方向のヘム加工性が劣り、さらに製造番号９の場合は導電率が高く、塗装焼付け硬化性が劣った。   On the other hand, in the production numbers 6 to 9, although the component composition of the alloy is within the range specified in the present invention, any of the production process conditions is out of the scope of the present invention, and any of the crystal orientation density conditions, etc. Does not satisfy the conditions defined in the present invention. Among these, the production number 6 is inferior in hem bendability, the production number 7 is inferior in hem bendability and ridging, and the production number 8 is inferior in hem workability in the 45 ° direction. In the case of No. 9, the conductivity was high and the paint bake hardenability was inferior.

なお以上の実施例は、この発明の効果を説明するためのものであり、実施例記載のプロセスおよび条件がこの発明の技術的範囲を制限するものではない。   In addition, the above Example is for demonstrating the effect of this invention, and the process and conditions as described in an Example do not restrict | limit the technical scope of this invention.

Claims (2)

Ｍｇ０．３〜１．５％（ｍａｓｓ％、以下同じ）、Ｓｉ０．３〜２．０％を含有し、かつＭｎ０．０３〜０．４％、Ｃｒ０．０１〜０．４％、Ｆｅ０．０３〜０．５％、Ｔｉ０．００５〜０．２％、Ｚｎ０．０３〜２．５％のうちから選ばれた１種または２種以上を含有し、さらにＣｕが１％以下に規制され、残部がＡｌおよび不可避的不純物よりなる合金を素材とし、ＤＣ鋳造法によりスラブに鋳造するにあたり、凝固後の冷却過程においてスラブ表面の６００℃から４００℃までの温度降下速度が３０℃／ｍｉｎ以上でかつスラブ厚中央部の６００℃から４００℃までの温度降下速度が５℃／ｍｉｎ以上となるように鋳造し、その後３００〜４５０℃の範囲内の温度に加熱して熱間圧延を開始し、かつその熱間圧延過程において熱間圧延開始板厚から１００ｍｍの中間板厚までの間における材料温度の降下量が１５０℃以内となるように制御するとともに、熱間圧延終了温度を２００〜３３０℃の範囲内に制御し、熱間圧延終了後圧延率３０％で冷間圧延を施した後、４８０℃以上の温度で溶体化処理を行ない、直ちに１００℃／ｍｉｎ以上の平均冷却速度で５０℃以上１５０℃未満の温度域まで冷却し、続いてその温度域内で１時間以上の安定化処理を行ない、これによりキューブ方位密度がランダム結晶方位を有する試料の３０〜２５０倍の範囲内にあり、かつ圧延方向軸ＲＤを基準としてキューブ理想方位を１０°回転させた結晶方位の方位密度が、板面法線軸ＮＤを基準としてキューブ理想方位を１０°回転させた方位の方位密度より高く、さらに０°、９０°耳率が５％以上で、しかも圧延方向と平行な方向のランクフォード値ｒ_０が０．５０〜１．５０の範囲内、板面内において圧延方向に対し４５°をなす方向のランクフォード値ｒ_４５が０．０１〜０．４５の範囲内、板面内において圧延方向に対し直交する方向のランクフォード値ｒ_９０が０．６０〜３．５０の範囲内にあり、さらに導電率が５４％ＩＡＣＳ以下であるアルミニウム合金板を得ることを特徴とする、成形加工用アルミニウム合金板の製造方法。 Mg 0.3-1.5% (mass%, the same shall apply hereinafter), Si 0.3-2.0%, Mn 0.03-0.4%, Cr 0.01-0.4%, Fe0.03 ~ 0.5%, Ti 0.005 to 0.2%, Zn contains 0.03 to 2.5% selected from one or more, further Cu is regulated to 1% or less, the balance Is made of an alloy consisting of Al and inevitable impurities, and when cast into a slab by DC casting, the temperature drop rate from 600 ° C. to 400 ° C. of the slab surface is 30 ° C./min or more in the cooling process after solidification and Casting so that the temperature drop rate from 600 ° C. to 400 ° C. at the central part of the slab thickness is 5 ° C./min or more, and then heating to a temperature in the range of 300 to 450 ° C. to start hot rolling, and Hot rolling in the hot rolling process Control is made so that the material temperature drop from the initial plate thickness to the intermediate plate thickness of 100 mm is within 150 ° C., and the hot rolling end temperature is controlled within the range of 200 to 330 ° C. After completion, after cold rolling at a rolling rate of 30%, solution treatment is performed at a temperature of 480 ° C or higher, and immediately cooled to a temperature range of 50 ° C or higher and lower than 150 ° C at an average cooling rate of 100 ° C / min or higher. Subsequently, the stabilization treatment is performed for 1 hour or longer in the temperature range, whereby the cube orientation density is in the range of 30 to 250 times that of the sample having a random crystal orientation, and the cube ideal is based on the rolling direction axis RD. The orientation density of the crystal orientation with the orientation rotated by 10 ° is higher than the orientation density of the orientation with the cube ideal orientation rotated by 10 ° with reference to the plate normal axis ND, and the 0 °, 90 ° ear ratio is 5%. Or more, yet within the scope of Lankford values _{r 0} of the rolling direction and the direction parallel from 0.50 to 1.50, the direction of Lankford values _{r 45} forming a 45 ° to the rolling direction in the plate surface 0. Within the range of 01 to 0.45, the Rankford value r ₉₀ in the direction orthogonal to the rolling direction in the plate surface is in the range of 0.60 to 3.50, and the conductivity is 54% IACS or less. A method for producing an aluminum alloy plate for forming, characterized by obtaining an aluminum alloy plate. 請求項１に記載の成形加工用アルミニウム合金板の製造方法において、
圧延方向に対し板面内で０°、４５°、９０°の３方向にそれぞれ圧延率８０％の冷間圧延を加えたときに、４５°方向の０．２％耐力値の上昇分が０°方向の０．２％耐力値の上昇分および９０°方向の０．２％耐力値上昇分よりも大きく、かつその４５°方向０．２％耐力値上昇分と、０°方向耐力値上昇分および９０°方向０．２％耐力値上昇分との差がそれぞれ５〜７０ＭＰａの範囲内にあるアルミニウム合金板を得ることを特徴とする、成形加工用アルミニウム合金板の製造方法。 In the manufacturing method of the aluminum alloy plate for shaping | molding of Claim 1,
When cold rolling with a rolling rate of 80% is applied in each of three directions of 0 °, 45 °, and 90 ° within the plate surface with respect to the rolling direction, the increase in 0.2% proof stress value in the 45 ° direction is 0. Increase in 0.2% proof stress value in the direction of 0.2 ° and increase in 0.2% proof stress value in the direction of 90 °, and increase in 0.2% proof stress value in the 45 ° direction and increase in proof stress value in the 0 ° direction A method for producing an aluminum alloy plate for forming, characterized by obtaining an aluminum alloy plate having a difference between the difference in the 90% direction and a 0.2% proof stress increase in the 90 ° direction within a range of 5 to 70 MPa.