WO2016140335A1 - Aluminum alloy plate - Google Patents

Aluminum alloy plate Download PDF

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WO2016140335A1
WO2016140335A1 PCT/JP2016/056719 JP2016056719W WO2016140335A1 WO 2016140335 A1 WO2016140335 A1 WO 2016140335A1 JP 2016056719 W JP2016056719 W JP 2016056719W WO 2016140335 A1 WO2016140335 A1 WO 2016140335A1
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plate
layer
cube
orientation
aluminum alloy
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PCT/JP2016/056719
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French (fr)
Japanese (ja)
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松本 克史
有賀 康博
久郎 宍戸
佐藤 和史
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株式会社神戸製鋼所
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Priority to JP2015-042565 priority
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Publication of WO2016140335A1 publication Critical patent/WO2016140335A1/en

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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/053Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with zinc as the next major constituent
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • C22C21/06Alloys based on aluminium with magnesium as the next major constituent
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • C22C21/06Alloys based on aluminium with magnesium as the next major constituent
    • C22C21/08Alloys based on aluminium with magnesium as the next major constituent with silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C21/00Alloys based on aluminium
    • C22C21/10Alloys based on aluminium with zinc as the next major constituent
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/047Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working

Abstract

In the present invention, a surface layer of a 7000 series aluminum alloy plate fabricated by a usual method is made to have a texture in which the cube orientation is promoted, and the center of the plate is made to have a texture in which the S orientation is promoted; that is, the surface layer of the plate and the center of the plate in the thickness direction are formed to have different textures that are most suitable in terms of shock absorption and strength, respectively. By doing so, the shock absorption in a car collision, which is evaluated by a VDA bending test as shown in fig. 1, is improved without lowering the strength.

Description

アルミニウム合金板Aluminum alloy plate
 本発明は、通常の圧延によって製造される7000系アルミニウム合金板であって、衝撃吸収性に優れた高強度7000系アルミニウム合金板に関するものである。 The present invention relates to a high-strength 7000 series aluminum alloy sheet that is a 7000 series aluminum alloy sheet manufactured by ordinary rolling and excellent in shock absorption.
 構造材料として自動車を例にとると、近年、地球環境などへの配慮から、自動車車体の軽量化の社会的要求はますます高まってきている。かかる要求に答えるべく、自動車車体のうち、パネル(フード、ドア、ルーフなどのアウタパネル、インナパネル)や、バンパリーンフォース(バンパーR/F)やドアビームなどの補強材などを、部分的に鋼板等の鉄鋼材料に代えて、アルミニウム合金材料を適用することが行われている。 Taking automobiles as an example of structural materials, in recent years, social demands for reducing the weight of automobile bodies are increasing due to consideration for the global environment. In order to respond to such demands, panels (outer panels such as hoods, doors and roofs, inner panels), bumper reinforcements (bumper R / F), door beams, and other reinforcing materials are partly made of steel, etc. Instead of the steel material, an aluminum alloy material is applied.
 ただ、自動車車体の更なる軽量化のためには、自動車部材のうちでも特に軽量化に寄与する、フレーム、ピラーなどの構造部材にも、アルミニウム合金材料の適用を拡大することが必要となる。これら自動車構造部材は、前記自動車パネルに比べて、材料の高強度化が必要であり、前記補強材として既に用いられている、JIS乃至AA 7000系アルミニウム合金を用いる必要がある。 However, in order to further reduce the weight of automobile bodies, it is necessary to expand the application of aluminum alloy materials to structural members such as frames and pillars that contribute particularly to reducing the weight of automobile members. These automobile structural members require higher strength of the material than the automobile panel, and it is necessary to use JIS or AA 7000 series aluminum alloy already used as the reinforcing material.
 前記バンパ補強材やドアビームなどの自動車構造部材の補強材は、7000系アルミニウム合金を熱間押出加工して製造される押出形材を素材として、既に汎用されている。これに対して、フレーム、ピラーなどの大型の構造部材は、鋳塊を均熱処理後に熱間圧延する、あるいは更に冷間圧延するような、常法によって製造される圧延板を素材とすることが好ましい。ただ、7000系アルミニウム合金の圧延板は、高合金ゆえのつくりにくさがあり、これまであまり実用化されていない。 The reinforcing material for automobile structural members such as the bumper reinforcing material and the door beam has already been widely used by using an extruded shape produced by hot extrusion of a 7000 series aluminum alloy. On the other hand, large structural members such as frames and pillars may be made of a rolled plate manufactured by a conventional method such as hot rolling after soaking or further cold rolling the ingot. preferable. However, 7000 series aluminum alloy rolled plates are difficult to make because of the high alloy, and have not been put to practical use so far.
 ただ、近年では、このような高強度な7000系アルミニウム合金圧延板(以下、7000系アルミニウム合金板、あるいは単に板とも言う)を、前記自動車構造部材を始め、鉄道車両などの構造部材に適用するために、集合組織を制御する検討が行われている。 However, in recent years, such a high-strength 7000 series aluminum alloy rolled plate (hereinafter also referred to as a 7000 series aluminum alloy plate or simply a plate) is applied to structural members such as the above-mentioned automobile structural members. Therefore, studies are underway to control the texture.
 7000系アルミニウム合金板の集合組織の制御例として、特許文献1、2では、構造材用の板の高強度化、高耐SCC性化を図るために、鋳塊を鍛造後に、温間加工域にて繰り返して圧延して、板組織を細かくしている。これは、板組織を細かくすることによって、耐SCC性低下の原因となる粒界と粒内との電位差の要因となる、方位差が20°以上の大傾角粒界を抑制して、3~10°の小傾角粒界が25%以上である集合組織を得るためである。
 ただ、特許文献1、2が、このような特殊な温間圧延の繰り返しを行うのは、通常の熱間圧延、冷間圧延の製造方法では、このような小傾角粒界が多い集合組織を得ることができないためである。したがって、通常の製造方法とは、その工程が大きく異なるため、板の製造方法としては実用的ではない。
As an example of control of the texture of a 7000 series aluminum alloy plate, in Patent Documents 1 and 2, in order to increase the strength of the structural material plate and increase the SCC resistance, the ingot is warm-worked after forging. The sheet structure is made finer by repeatedly rolling. This is because, by making the plate structure fine, a large-angle grain boundary with an orientation difference of 20 ° or more, which causes a potential difference between the grain boundary and the grain boundary, which causes a decrease in SCC resistance, is suppressed. This is to obtain a texture in which the 10 ° small-angle grain boundary is 25% or more.
However, Patent Documents 1 and 2 repeat such a special warm rolling because a texture having a large number of such low-angle grain boundaries is used in a normal hot rolling or cold rolling manufacturing method. It is because it cannot be obtained. Therefore, since the process is greatly different from a normal manufacturing method, it is not practical as a method for manufacturing a plate.
 これに対して、特許文献3では、通常の板の製造方法によって製造される、強度と耐SCC性の両方に優れた、自動車部材用の7000系アルミニウム合金板を提供することを目的として、板の集合組織を制御している。
 具体的には、Zn:3.0~8.0%、Mg:0.5~4.0%を含み、残部がAlおよび不可避的不純物からなる組成のAl-Zn-Mg系アルミニウム合金板の、平均結晶粒径が15μm以下であるとともに、Brass方位、S方位、Cu方位を有する結晶粒の平均合計面積率が30%以上である集合組織を有することとしている。
On the other hand, in patent document 3, it is a board for the purpose of providing the 7000 series aluminum alloy board for motor vehicle members which was manufactured with the manufacturing method of the normal board, and was excellent in both the intensity | strength and SCC resistance. Has control over the texture.
Specifically, an Al—Zn—Mg-based aluminum alloy plate having a composition containing Zn: 3.0 to 8.0%, Mg: 0.5 to 4.0%, and the balance consisting of Al and inevitable impurities. In addition, the average crystal grain size is 15 μm or less, and the average total area ratio of crystal grains having the Brass orientation, the S orientation, and the Cu orientation is 30% or more.
 すなわち、通常の等軸な再結晶組織ではなく、むしろ前記押出形材に類似した加工組織として、繊維状組織で構成し、これを集合組織の観点から、主方位がBrass方位、S方位、Cu方位であるものと規定している。
 この特許文献3では、このような集合組織とすることによって、板に歪が入った場合に、局所的に集中せずに、均一に転位する組織とできるとしている。そして、常法によって製造された7000系アルミニウム合金板であっても、0.2%耐力が350MPa以上の高強度とし、伸びも大きくして成形性を確保でき、高強度であるにも関わらず、耐SCC性の低下も抑制できるとしている。
That is, it is not a normal equiaxed recrystallized structure, but rather a fibrous structure as a processed structure similar to the extruded profile. From the viewpoint of the texture, the main directions are the Brass direction, S direction, Cu It is stipulated to be a bearing.
In this patent document 3, it is said that by forming such a texture, it is possible to obtain a structure in which dislocations are uniformly distributed without locally concentrating when the plate is distorted. And even if it is a 7000 series aluminum alloy plate manufactured by a conventional method, the 0.2% proof stress is set to a high strength of 350 MPa or more, the elongation is increased, the formability can be secured, and the high strength is achieved. It is said that a decrease in SCC resistance can also be suppressed.
特開2001-335874号公報JP 2001-335874 A 特開2002-241882号公報Japanese Patent Laid-Open No. 2002-241882 特開2014-62285号公報JP 2014-62285 A
 ここで、近年の自動車の衝突安全基準のレベルアップによって、ヨーロッパなどでは、前記フレーム、ピラーなどの自動車構造部材に、ドイツ自動車工業会(VDA)で規格化されている「VDA238-100 Plate bending test for metallic materials(以降、VDA曲げ試験と言う)」にて評価される、自動車の衝突時における衝撃吸収性(圧壊特性)を満たすことが求められるようになっている。 Here, with the recent improvement of automobile safety standards, in Europe and other countries, the VDA238-100 Plate Bending Test has been standardized by the German Automobile Manufacturers Association (VDA) for automotive structural members such as frames and pillars. It is required to satisfy the impact absorption (crush characteristics) at the time of automobile collision, which is evaluated by “for metallic materials (hereinafter referred to as VDA bending test)”.
 このような厳しい安全基準に対して、板の組織を、前記特許文献1、2のように、大傾角粒界を抑制して、3~10°の小傾角粒界を増した集合組織としても、また、前記特許文献3のように、繊維状組織で構成した集合組織としても、前記自動車の衝突時における衝撃吸収性(圧壊特性)を満たすことができない。 With respect to such strict safety standards, the structure of the plate can be a texture with a large tilt angle boundary increased by 3 to 10 ° by suppressing the large tilt grain boundary as in Patent Documents 1 and 2. Further, as in Patent Document 3, even a texture composed of a fibrous structure cannot satisfy the shock absorption (crushing characteristics) at the time of collision of the automobile.
 また、通常の圧延によって製造される7000系アルミニウム合金板に、その強度を低下させずに、自動車の衝突時における衝撃吸収性(圧壊特性)を満たす手段ついては、未だ有効な手段が不明で、なお解明の余地がある。 In addition, as for means for satisfying the impact absorption (crushing characteristics) at the time of automobile collision without reducing the strength of the 7000 series aluminum alloy plate produced by ordinary rolling, the effective means is still unknown. There is room for clarification.
 このような状況に鑑み、本発明の目的は、通常の圧延によって製造される7000系アルミニウム合金板であって、強度を低下させずに、自動車の衝突時における衝撃吸収性(圧壊特性)を向上させた、7000系アルミニウム合金板を提供することである。 In view of such circumstances, an object of the present invention is a 7000 series aluminum alloy plate manufactured by ordinary rolling, and improves impact absorption (crush characteristics) at the time of automobile collision without reducing strength. And providing a 7000 series aluminum alloy plate.
 この目的を達成するために、本発明のアルミニウム合金板の要旨は、質量%で、Zn:2.0~9.0%、Mg:0.5~4.5%を各々含有するとともに、Cu:0.5%以下(但し0%を含む)、Zr:0.15%以下(但し0%を含む)、Mn:0.2%以下(但し0%を含む)、Cr:0.15%以下(但し0%を含む)、Sc:0.05%以下(但し0%を含む)に各々規制し、残部がAl及び不可避的不純物からなるアルミニウム合金板であって、この板の表面から板厚の15%の深さまでの表層部の結晶粒のうち、Cube方位を有する結晶粒の面積率を[表層部Cube]、S方位を有する結晶粒の面積率を[表層部S]と各々するとともに、前記板の板厚中心部における結晶粒のうち、Cube方位を有する結晶粒の面積率を[板厚中心部Cube]、S方位を有する結晶粒の面積率を[板厚中心部S]と各々した時、前記表層部は、平均結晶粒径が40μm以下の等軸な再結晶組織であるとともに、前記[表層部Cube]が10%以上で、かつ、前記[表層部S]が10%以上、40%以下であり、かつ、前記[表層部Cube]の前記[板厚中心部Cube]に対する割合である[表層部Cube]/[板厚中心部Cube]が1.0を超えているとともに、前記[表層部S]の前記[板厚中心部S]に対する割合である[表層部S]/[板厚中心部S]が1.0未満であるような、前記表層部と前記板厚中心部とが異なる集合組織を有することとする。 In order to achieve this object, the gist of the aluminum alloy sheet of the present invention is, in mass%, containing Zn: 2.0 to 9.0%, Mg: 0.5 to 4.5%, and Cu. : 0.5% or less (including 0%), Zr: 0.15% or less (including 0%), Mn: 0.2% or less (including 0%), Cr: 0.15% The following is (including 0%) and Sc: 0.05% or less (including 0%), respectively, and the balance is an aluminum alloy plate made of Al and unavoidable impurities. Of the crystal grains in the surface layer portion up to a depth of 15% of the thickness, the area ratio of the crystal grains having the Cube orientation is [surface layer portion Cube], and the area ratio of the crystal grains having the S orientation is [surface layer portion S]. In addition, among the crystal grains in the center of the plate thickness of the plate, the surface of the crystal grains having the Cube orientation When the rate is [plate thickness center portion Cube] and the area ratio of crystal grains having S orientation is [plate thickness center portion S], the surface layer portion is equiaxed recrystallized with an average crystal grain size of 40 μm or less. The [surface layer portion Cube] is 10% or more, the [surface layer portion S] is 10% or more and 40% or less, and the [sheet thickness center of the [surface layer portion Cube] [Surface layer portion Cube] / [plate thickness center portion Cube] is more than 1.0 and is a ratio of [surface layer portion S] to [sheet thickness center portion S]. The surface layer portion and the plate thickness center portion have different textures such that the surface layer portion S] / [plate thickness center portion S] is less than 1.0.
 本発明では、溶体化および焼入れ処理後の7000系アルミニウム合金板の集合組織に着目して、VDA曲げ試験にて評価される、自動車衝突時における衝撃吸収性(圧壊特性)との関係を解析した。その結果、この衝撃吸収性は、特に板の表層部の集合組織が影響し、板の表層部をCubeが発達した特定の集合組織にすることによって向上することを見出した。また、この際に、板の中心部(板厚中心部)をS方位が発達した特定の集合組織にすることによって、強度が保持されることも見出した。 In the present invention, focusing on the texture of the 7000 series aluminum alloy plate after solution treatment and quenching treatment, the relationship with the shock absorption (crushing property) at the time of automobile collision, which is evaluated by the VDA bending test, was analyzed. . As a result, the present inventors have found that this shock absorption is particularly affected by the texture of the surface layer portion of the plate, and is improved by making the surface layer portion of the plate a specific texture in which Cube is developed. Further, at this time, it was also found that the strength is maintained by making the central portion (plate thickness central portion) of the plate a specific texture in which the S orientation is developed.
 すなわち、板の表層部と板厚中心部とを、衝撃吸収性と強度とに対して、それぞれ最適な集合組織に作り分けることで、強度を低下させずに、自動車の衝突時における衝撃吸収性を向上させられることを見出した。 In other words, by creating the optimal texture for the shock absorption and strength of the surface layer of the plate and the center of the plate thickness, the shock absorption at the time of a car collision can be achieved without reducing the strength. It was found that can be improved.
 このように、本発明は、前記表層部と前記板厚中心部とが異なる集合組織を有することによって、通常の圧延によって製造される7000系アルミニウム合金板に、強度と衝撃吸収性を兼備させることができる。したがって、このような特性が要求される、前記自動車や鉄道車両などの構造部材用に好適な7000系アルミニウム合金板を提供できる。 As described above, according to the present invention, the surface layer portion and the plate thickness center portion have different textures so that the 7000 series aluminum alloy plate manufactured by normal rolling has both strength and shock absorption. Can do. Accordingly, it is possible to provide a 7000 series aluminum alloy plate suitable for structural members such as the automobiles and railway vehicles, which require such characteristics.
衝撃吸収性を評価するVDA曲げ試験の態様を示す斜視図である。It is a perspective view which shows the aspect of the VDA bending test which evaluates shock absorption.
 本発明で言うアルミニウム合金板とは、鋳塊を均熱処理後に熱間圧延され、更に冷間圧延された冷延板であって、更に溶体化処理などの調質が施される、通常の圧延法によって製造された7000系アルミニウム合金板のことを言う。言い換えると、前記特許文献1、2のような、鋳塊を鍛造した上で温間圧延を何回も繰り返すような特殊な圧延方法や製法により製造される板を含まない。 The aluminum alloy sheet referred to in the present invention is a cold-rolled sheet that is hot-rolled after the soaking of the ingot and further cold-rolled, and is further subjected to tempering such as solution treatment. It means a 7000 series aluminum alloy plate manufactured by the method. In other words, it does not include a plate manufactured by a special rolling method or manufacturing method in which warm rolling is repeated many times after forging an ingot as in Patent Documents 1 and 2.
 このような7000系アルミニウム合金板は、伸びフランジ加工(バーリング加工、穴拡げ加工)などを含む、プレス成形や加工が施された上で、自動車、自転車、鉄道車両などの構造部材とされる。
 以下に、本発明の実施の形態につき、要件ごとに具体的に説明する。
Such a 7000 series aluminum alloy plate is used as a structural member for automobiles, bicycles, railway vehicles, etc. after being subjected to press molding and processing including stretch flange processing (burring processing, hole expansion processing) and the like.
Hereinafter, embodiments of the present invention will be specifically described for each requirement.
アルミニウム合金組成:
 先ず、本発明アルミニウム合金板の化学成分組成について、各元素の限定理由を含めて、以下に説明する。なお、各元素の含有量の%表示は全て質量%の意味である。
Aluminum alloy composition:
First, the chemical component composition of the aluminum alloy sheet of the present invention will be described below, including reasons for limiting each element. In addition,% display of content of each element means the mass% altogether.
 本発明アルミニウム合金板の化学成分組成は、Al-Zn-Mg系の7000系アルミニウム合金として、自動車などの構造部材に要求される、強度と衝撃吸収性(圧壊特性)、耐SCC性などの諸特性を保証するために決定される。この観点から、本発明アルミニウム合金板の化学成分組成は、質量%で、Zn:2.0~9.0%、Mg:0.5~4.5%を各々含有するとともに、Cu:0.5%以下(但し0%を含む)、Zr:0.15%以下(但し0%を含む)、Mn:0.2%以下(但し0%を含む)、Cr:0.15%以下(但し0%を含む)、Sc:0.05%以下(但し0%を含む)に各々規制し、残部がAl及び不可避的不純物からなるものとする。 The chemical composition of the aluminum alloy sheet of the present invention is an Al—Zn—Mg based 7000 series aluminum alloy, which is required for structural members such as automobiles, such as strength and shock absorption (crush characteristics), and SCC resistance. Determined to guarantee properties. From this point of view, the chemical composition of the aluminum alloy sheet of the present invention is Zn by mass: 2.0 to 9.0%, Mg: 0.5 to 4.5%, and Cu: 0.00%. 5% or less (including 0%), Zr: 0.15% or less (including 0%), Mn: 0.2% or less (including 0%), Cr: 0.15% or less (however, (Including 0%) and Sc: 0.05% or less (including 0%), and the balance is made of Al and inevitable impurities.
 この組成に、更に、質量%で、Ag:0.01~0.2%、Sn:0.001~0.1%の1種又は2種を含んでも良い。これに加えて、あるいはこれとは別に、更に、質量%で、Ti:0.001~0.1%を含んでも良い。 The composition may further contain one or two of Ag: 0.01 to 0.2% and Sn: 0.001 to 0.1% by mass%. In addition to this, or in addition to this, Ti: 0.001 to 0.1% may also be contained by mass%.
Zn:2.0~9.0%
 必須の合金元素であるZnは、Mgとともに、溶体化処理後の室温時効時にクラスタ(微細析出物)を形成して加工硬化特性を向上させる。また、人工時効処理時に時効析出物を形成して強度を向上させる。Zn含有量が2.0質量%未満では強度が不足し、また集合組織を規定通りに制御できず、強度と成形性とのバランスが低下する可能性もある。一方Znが9.0質量%を超えると粒界析出物MgZnが増えて粒界腐食が起こりやすくなり、耐食性が劣化する。従って、Zn含有量の下限は2.0%、好ましくは3.7%である。また、Zn含有量の上限は9.0%、好ましくは8.3%である。
Zn: 2.0 to 9.0%
Zn, which is an essential alloy element, together with Mg, forms clusters (fine precipitates) during room temperature aging after solution treatment and improves work hardening characteristics. Moreover, an aging precipitate is formed during the artificial aging treatment to improve the strength. If the Zn content is less than 2.0% by mass, the strength is insufficient, the texture cannot be controlled as prescribed, and the balance between strength and formability may be reduced. On the other hand, if Zn exceeds 9.0% by mass, the grain boundary precipitate MgZn 2 increases and intergranular corrosion easily occurs, and the corrosion resistance deteriorates. Therefore, the lower limit of the Zn content is 2.0%, preferably 3.7%. Further, the upper limit of the Zn content is 9.0%, preferably 8.3%.
Mg:0.5~4.5%
 必須の合金元素であるMgは、Znとともに、溶体化処理後の室温時効時にクラスタ(微細析出物)を形成して加工硬化特性を向上させる。また、人工時効処理時に時効析出物を形成して強度を向上させる。Mg含有量が0.5%未満では強度が不足し、4.5質量%を超えると、鋳造割れが発生し、また板の圧延性が低下し、板の製造試作が困難になる。従って、Mg含有量の下限は0.5%、好ましくは1.4%である。また、Mg含有量の上限は4.5%、好ましくは4.3%である。ここで、必要な強度を得るためには、Mg、Znの各含有量を互いにバランスさせるのが好ましい。
Mg: 0.5-4.5%
Mg, which is an essential alloy element, together with Zn, forms clusters (fine precipitates) during room temperature aging after solution treatment, thereby improving work hardening characteristics. Moreover, an aging precipitate is formed during the artificial aging treatment to improve the strength. If the Mg content is less than 0.5%, the strength is insufficient. If the Mg content exceeds 4.5% by mass, casting cracks occur, the rollability of the plate decreases, and it becomes difficult to produce a prototype of the plate. Therefore, the lower limit of the Mg content is 0.5%, preferably 1.4%. Further, the upper limit of the Mg content is 4.5%, preferably 4.3%. Here, in order to obtain a required strength, it is preferable to balance the contents of Mg and Zn with each other.
Cu、Zr、Mn、Cr、Sc
 Cu、Zr、Mn、Cr、Scは、いずれも、溶体化処理時の板の再結晶温度を顕著に上昇させるため、溶体化処理での板の再結晶化の加熱温度が高くなり、板の表面から板厚の15%の深さまでの表層部のCube方位の発達を阻害する作用がある。このため、これらの元素の含有量が多すぎると、前記表層部におけるCube方位を有する結晶粒の面積率[表層部Cube]を、本発明で規定するように大きくできなくなる。また、これらの元素の含有量が多すぎると、この表層部のS方位の発達を助長するため、S方位を有する結晶粒の面積率[表層部S]を、本発明で規定するように制限できなくなる。
Cu, Zr, Mn, Cr, Sc
All of Cu, Zr, Mn, Cr, and Sc significantly increase the recrystallization temperature of the plate during the solution treatment, so that the heating temperature for recrystallization of the plate during the solution treatment increases. It has the effect of inhibiting the development of the Cube orientation of the surface layer from the surface to a depth of 15% of the plate thickness. For this reason, when there is too much content of these elements, the area ratio [surface part Cube] of the crystal grain which has the Cube orientation in the said surface part cannot become large so that it may prescribe | regulate in this invention. In addition, if the content of these elements is too large, the development of the S orientation of the surface layer portion is promoted, so the area ratio [surface layer portion S] of the crystal grains having the S orientation is limited as defined in the present invention. become unable.
 このため、本発明では、Cu:0.5%以下(但し0%を含む)、Zr:0.15%以下(但し0%を含む)、Mn:0.2%以下(但し0%を含む)、Cr:0.15%以下(但し0%を含む)、Sc:0.05%以下(但し0%を含む)に、各々敢えて規制することが必要である。 Therefore, in the present invention, Cu: 0.5% or less (including 0%), Zr: 0.15% or less (including 0%), Mn: 0.2% or less (including 0%) ), Cr: 0.15% or less (including 0%), and Sc: 0.05% or less (including 0%), respectively.
 ちなみに、通常、Cuは、Al-Zn-Mg系合金の耐SCC性を向上させる作用や強度向上効果もあるので、添加されることが多い。また、Zr、Mn、Cr、Scも、鋳塊及び最終製品板の結晶粒の微細化による強度向上のために、添加されることが多い。このため、通常は、Cu、Zr、Mn、Cr、Scによって、前記表層部におけるCube方位を有する結晶粒の面積率[表層部Cube]が、本発明で規定するように大きくできなくなる蓋然性が高い。また、この表層部のS方位を有する結晶粒の面積率[表層部S]を、本発明で規定するように制限できなくなる蓋然性も高い。 Incidentally, Cu is usually added in many cases because it has an effect of improving the SCC resistance of an Al—Zn—Mg-based alloy and an effect of improving the strength. Also, Zr, Mn, Cr, and Sc are often added to improve the strength by refining the crystal grains of the ingot and the final product plate. For this reason, normally, the probability that the area ratio [surface layer portion Cube] of the crystal grains having the Cube orientation in the surface layer portion cannot be increased by Cu, Zr, Mn, Cr, and Sc as defined in the present invention is high. . In addition, there is a high probability that the area ratio [surface layer portion S] of the crystal grains having the S orientation of the surface layer portion cannot be restricted as defined in the present invention.
Ag:0.01~0.2%、Sn:0.001~0.1%の1種又は2種
 Ag及びSnは、構造材への成形加工後の人工時効処理によって強度向上に寄与する時効析出物を緊密微細に析出させ、高強度化を促進する効果があるので、必要に応じて選択的に含有させる。これらをいずれか一方又は両方含有する場合、Sn含有量が0.001%未満、Ag含有量が0.01%未満では、強度向上効果が小さい。一方、SnやAg含有量が多すぎると、圧延性及び溶接性などの諸特性を却って低下させる。また、強度向上効果も飽和し、Agに関しては高価となるだけである。従って、Ag:0.01~0.2%、Sn:0.001~0.1%の範囲とする。
One or two types of Ag: 0.01 to 0.2%, Sn: 0.001 to 0.1% Ag and Sn are aging that contributes to strength improvement by artificial aging treatment after molding processing to a structural material Precipitates are closely and finely precipitated, and have the effect of promoting high strength, so they are selectively contained as required. When one or both of these are contained, if the Sn content is less than 0.001% and the Ag content is less than 0.01%, the strength improvement effect is small. On the other hand, when there is too much Sn and Ag content, various characteristics, such as rolling property and weldability, will be reduced. In addition, the strength improvement effect is saturated, and Ag is only expensive. Therefore, Ag: 0.01 to 0.2% and Sn: 0.001 to 0.1% are set.
Ti:0.001~0.1%
 Tiは、Bとともに、圧延板としては不純物であるが、アルミニウム合金鋳塊の結晶粒を微細化する効果があるので、7000系合金としてJIS規格で規定する範囲での各々の含有を許容する。Tiが0.001%未満では結晶粒微細化効果が得られない。一方、Tiが0.1%を超える場合、粗大な化合物を形成し、機械的特性が劣化する。従って、Tiの上限は0.1%、好ましくは0.05%以下とする。また、このTiとともに、Bを0.03%まで含有することを許容する。Bが0.03%を超える場合、粗大な化合物を形成し、機械的特性が劣化する。
Ti: 0.001 to 0.1%
Ti, together with B, is an impurity in the rolled plate, but has the effect of refining the crystal grains of the aluminum alloy ingot, so that it is allowed to be contained as a 7000 series alloy within the range specified by the JIS standard. If Ti is less than 0.001%, the effect of crystal grain refinement cannot be obtained. On the other hand, when Ti exceeds 0.1%, a coarse compound is formed and the mechanical properties are deteriorated. Therefore, the upper limit of Ti is 0.1%, preferably 0.05% or less. Further, it is allowed to contain B up to 0.03% with this Ti. When B exceeds 0.03%, a coarse compound is formed and the mechanical properties deteriorate.
その他の元素:
 これら記載した以外のその他の元素は不可避的な不純物である。溶解原料として、純アルミニウム地金以外に、アルミニウム合金スクラップの使用による、これら不純物元素の混入なども想定(許容)して、7000系合金のJIS規格で規定する範囲での各々の含有を許容する。例えば、不可避的な不純物として、Fe:0.5%以下、Si:0.5%以下であれば、本発明に係るアルミニウム合金板の特性に影響せず、含有が許容される。
Other elements:
Other elements other than those described are inevitable impurities. As a melting raw material, in addition to pure aluminum ingots, the inclusion of these impurity elements due to the use of aluminum alloy scrap is assumed (allowed), and each content within the range specified by the JIS standard of 7000 series alloys is allowed. . For example, if the inevitable impurities are Fe: 0.5% or less and Si: 0.5% or less, the inclusion is allowed without affecting the characteristics of the aluminum alloy sheet according to the present invention.
組織:
 本発明の7000系アルミニウム合金板は、前提として、その組成と多くの製造工程とが、従来の7000系アルミニウム合金板や、その製造方法(通常の圧延法)と共通する。このため、板組織として、微細なナノレベルのサイズの析出物が、結晶粒内に多数存在して、強度や耐食性などの基本特性を満たす土台となっている点も共通している。これらの微細なナノレベルのサイズの析出物とは、結晶粒内に生成する、前記MgとZnとの金属間化合物(組成はMgZnなど)であり、これに前記組成に応じた元素が含まれる微細分散相である。
Organization:
As a premise, the 7000 series aluminum alloy plate of the present invention has the same composition and many production steps as the conventional 7000 series aluminum alloy plate and its production method (normal rolling method). For this reason, as the plate structure, a large number of fine nano-sized precipitates are present in the crystal grains, which is the basis for satisfying basic characteristics such as strength and corrosion resistance. These fine nano-level precipitates are the intermetallic compounds of Mg and Zn (composition is MgZn 2 and the like) that are generated in the crystal grains, and include elements corresponding to the composition. It is a finely dispersed phase.
集合組織:
 以上の7000系アルミニウム合金板の組成を前提として、本発明では、VDA曲げ試験にて評価される、自動車衝突時における衝撃吸収性(圧壊特性)や、強度、耐食性などの特性の向上のために、この7000系アルミニウム合金板の組織を制御する。
Texture:
Based on the above-mentioned composition of the 7000 series aluminum alloy plate, in the present invention, in order to improve characteristics such as shock absorption (crush characteristics), strength, and corrosion resistance, which are evaluated by a VDA bending test, in an automobile collision. The structure of the 7000 series aluminum alloy plate is controlled.
 具体的には、先ず、この板の表面から板厚の15%の深さまでの表層部を、平均結晶粒径が50μm以下の等軸な再結晶組織とする。この表層部の平均結晶粒径が50μmを超えて粗大化するか、等軸な再結晶組織ではなく、圧延方向に伸長した細長い加工組織となった(加工組織のままの)場合、VDA曲げ性を向上させるCube方位を有する結晶粒が発達せずに、衝撃吸収性(圧壊特性)が低下する。
 ここで、板の表面から板厚の15%の深さとは、板(供試材)表面の酸化皮膜を研磨により除去した後の、板のアルミニウムマトリックスの最表面からの深さである。
Specifically, first, the surface layer portion from the surface of the plate to a depth of 15% of the plate thickness is made an equiaxed recrystallized structure having an average crystal grain size of 50 μm or less. When the average crystal grain size of this surface layer exceeds 50 μm, or when it becomes an elongated work structure elongated in the rolling direction instead of an equiaxed recrystallized structure (as it is), VDA bendability Impact absorption (crushing properties) is reduced without developing crystal grains having a Cube orientation that improve the strength.
Here, the depth of 15% of the plate thickness from the surface of the plate is the depth from the outermost surface of the aluminum matrix of the plate after removing the oxide film on the surface of the plate (test material) by polishing.
 勿論、この表層部だけでなく、より板の内部に向かって、このような平均結晶粒径を50μm以下とした等軸で微細な再結晶組織とできれば良いが、前記した常法による板の製造では、特に板厚が厚い場合など、板厚中心部などの板の内部組織まで、平均結晶粒径を50μm以下とした等軸で微細な再結晶組織とすることは難しい。 Of course, not only this surface layer portion but also the inside of the plate, it is sufficient that such an average crystal grain size is 50 μm or less, and it is possible to obtain a fine recrystallized structure with the same axis. Then, especially when the plate thickness is large, it is difficult to obtain an equiaxed and fine recrystallized structure with an average crystal grain size of 50 μm or less up to the internal structure of the plate such as the central portion of the plate thickness.
 また、前記衝撃吸収性(圧壊特性)には、板厚中心部などの板の内部組織の有り様よりも、板の表面から板厚の15%の深さまでの表層部の、Cube方位を有する結晶粒組織が、大きく影響する。このため、本発明では、板の表面から板厚の15%の深さまでの表層部の集合組織を規定する。
 この表層部の厚みが、板の表面から板厚の15%未満では、Cube方位やS方位の面積率が後述する規定を満たしても、板のごく表面だけなど、表層部が薄すぎて、前記衝撃吸収性の向上効果が小さくなる。また、この集合組織を有する表層部が、板の表面から板厚の15%を超える深さまで存在しては、表層部が厚すぎることとなり、強度を保証する板の中心部の厚さが薄くなりすぎて、板全体としての高強度を保証できなくなる。
Further, in the shock absorption (crushing property), a crystal having a Cube orientation in the surface layer portion from the surface of the plate to a depth of 15% of the plate thickness rather than the state of the internal structure of the plate such as the central portion of the plate thickness. The grain structure is greatly affected. For this reason, in this invention, the texture of the surface layer part from the surface of a board to the depth of 15% of board thickness is prescribed | regulated.
If the thickness of the surface layer portion is less than 15% of the plate thickness from the surface of the plate, the surface layer portion is too thin, such as only the very surface of the plate, even if the area ratio of the Cube orientation or S orientation satisfies the regulations described later, The effect of improving the shock absorption becomes small. Further, if the surface layer portion having this texture exists from the surface of the plate to a depth exceeding 15% of the plate thickness, the surface layer portion is too thick, and the thickness of the center portion of the plate that guarantees the strength is thin. As a result, the high strength of the entire plate cannot be guaranteed.
表層部と板厚中心部との集合組織の複合化:
 上記のように、板の表層部を微細で等軸な再結晶組織とした上で、本発明では、板の表層部を、強度よりも衝撃吸収性(圧壊特性)に優れたCube方位を主とする集合組織とし、板の板厚中心部は、衝撃吸収性(圧壊特性)よりも強度に優れたS方位を主とする集合組織する。
 すなわち、本発明では、板の表層部の前記衝撃吸収性(圧壊特性)に効くCube方位を、その絶対量を確保するとともに、板厚中心部のCube方位よりも多くして、前記衝撃吸収性(圧壊特性)を向上させる。
 と同時に、板厚中心部においては、強度の向上に効くS方位の絶対量を確保し、この絶対量を、前記板厚中心部のS方位の面積率を、前記表層部のS方位の面積率より多くすることで規定して、板の強度を確保する。
Composite texture of surface layer and center of plate thickness:
As described above, after making the surface layer portion of the plate into a fine and equiaxed recrystallized structure, in the present invention, the surface layer portion of the plate mainly has a Cube orientation that is superior in impact absorption (crushing property) to strength. The thickness center portion of the plate has a texture mainly having an S orientation superior in strength to shock absorption (crushing property).
That is, in the present invention, the Cube orientation effective for the shock absorption (crushing characteristics) of the surface layer portion of the plate is ensured in its absolute amount, and is made larger than the Cube orientation of the center portion of the plate thickness, thereby the shock absorption. Improve (crush characteristics).
At the same time, in the center portion of the plate thickness, an absolute amount of the S orientation effective for improving the strength is secured, and this absolute amount is calculated based on the area ratio of the S orientation of the center portion of the plate thickness and the area of the S orientation of the surface layer portion. The strength of the plate is ensured by prescribing more than the rate.
 このように、本発明では、板の表層部と板厚中心部とを、衝撃吸収性と強度とに対して、それぞれ最適な集合組織に作り分け、前記表層部と前記板厚中心部とで集合組織と作用とが異なる、板厚方向での複合組織を有する板とする。 As described above, in the present invention, the surface layer portion and the plate thickness center portion of the plate are formed into optimum textures respectively for the shock absorption and strength, and the surface layer portion and the plate thickness center portion A plate having a composite structure in the thickness direction, which has a different texture and action.
Cube方位とS方位の表層部と板厚中心部とでの各面積率:
 具体的に、本発明では、表面から板厚の15%の深さまでの板の表層部の結晶粒のうち、Cube方位を有する結晶粒の面積率を[表層部Cube]とし、S方位を有する結晶粒の面積率を[表層部S]とする。そして、前記板の板厚中心部における結晶粒のうち、Cube方位を有する結晶粒の面積率を[板厚中心部Cube]とし、S方位を有する結晶粒の面積率を[板厚中心部S]とする。
Each area ratio in the surface layer part of Cube orientation and S orientation, and the thickness center part:
Specifically, in the present invention, among the crystal grains in the surface layer portion of the plate from the surface to a depth of 15% of the plate thickness, the area ratio of the crystal grains having the Cube orientation is defined as [surface layer portion Cube], and the S orientation is obtained. Let the area ratio of a crystal grain be [surface layer part S]. Of the crystal grains in the plate thickness center portion of the plate, the area ratio of the crystal grains having the Cube orientation is [plate thickness center portion Cube], and the area ratio of the crystal grains having the S orientation is [plate thickness center portion S]. ].
 そして、板の板厚の15%の深さまでの表層部の結晶粒のうち、前記[表層部Cube]を10%以上とし、かつ、前記[表層部S]を10%以上、40%以下とする。
 同時に、前記[表層部Cube]と前記[板厚中心部Cube]との割合である[表層部Cube]/[板厚中心部Cube]を1.0を超えるものとし、前記[表層部S]と前記[板厚中心部S]との割合である[表層部S]/[板厚中心部S]を1.0未満とする。
 ちなみに、常法により製造された板は、[表層部Cube]/[板厚中心部Cube]が1.0、[表層部S]/[板厚中心部S]が1.0、板の表層部と板厚中心部とが互いに同じ集合組織となる。
Of the crystal grains in the surface layer portion up to a depth of 15% of the plate thickness, the [surface layer portion Cube] is set to 10% or more, and the [surface layer portion S] is set to 10% or more and 40% or less. To do.
At the same time, [surface layer portion Cube] / [plate thickness center portion Cube], which is a ratio of the [surface layer portion Cube] and the [plate thickness center portion Cube], exceeds 1.0, and the [surface layer portion S] And [surface layer portion S] / [plate thickness center portion S], which is a ratio of the above and [plate thickness center portion S], is less than 1.0.
Incidentally, the plate manufactured by a conventional method has a [surface layer portion Cube] / [plate thickness center portion Cube] of 1.0, [surface layer portion S] / [plate thickness center portion S] of 1.0, and a surface layer of the plate. The portion and the plate thickness center portion have the same texture.
 前記[表層部Cube]の上限は、製造限界からすると、80%程度である。この点で、前記[表層部Cube] の好ましい範囲は10%以上、80%以下の範囲である。 The upper limit of the [surface layer part Cube] is about 80% from the manufacturing limit. In this respect, a preferable range of the [surface layer portion Cube] is a range of 10% or more and 80% or less.
 このような前記[表層部Cube]とすることによって、常法によって製造された7000系アルミニウム合金板であっても、VDA曲げ試験によって、板に歪が入った場合に、局所的に歪が集中せずに、均一に変形する組織とできる。これによって、前記[板厚中心部S]によって得られた、0.2%耐力が350MPa以上であるような高強度であっても、自動車衝突時における衝撃吸収性(圧壊特性)が高い板特性を得られる。 By adopting such a [surface layer part Cube], even if it is a 7000 series aluminum alloy plate produced by a conventional method, when the plate is distorted by the VDA bending test, the strain is locally concentrated. Without causing the tissue to deform uniformly. As a result, even if the 0.2% proof stress is 350 MPa or more obtained by the [plate thickness center portion S], the plate properties have high shock absorption (crushing properties) at the time of automobile collision. Can be obtained.
 前記[表層部Cube]が10%未満と少ないか、前記[表層部S]が40%超と多すぎるか、前記[表層部Cube]/[板厚中心部Cube]が1.0以下で、[表層部Cube]が少なすぎると、VDA曲げ性が低下し、自動車衝突時における衝撃吸収性(圧壊特性)が低下する。また、前記[表層部Cube]/[板厚中心部Cube]が1.0以下で、[板厚中心部Cube]が多すぎると、後述するように[板厚中心部S]が少なくなりすぎて、強度が低下する。 The [surface layer portion Cube] is less than 10%, the [surface layer portion S] is more than 40%, or the [surface layer portion Cube] / [plate thickness center portion Cube] is 1.0 or less, When there is too little [surface layer part Cube], VDA bendability will fall and the shock absorptivity (crushing characteristic) at the time of a car collision will fall. Further, if the [surface layer portion Cube] / [plate thickness center portion Cube] is 1.0 or less and the [plate thickness center portion Cube] is too much, the [plate thickness center portion S] becomes too small as will be described later. As a result, the strength decreases.
 一方、前記[表層部S]が10%未満と少ないか、前記[表層部S]/[板厚中心部S]が1.0以上と、[板厚中心部S]が少なすぎるか、[板厚中心部S]が多すぎると、強度が低下する。
 ここで、VDA曲げ性や強度の、より一層の向上のためには、好ましくは、[表層部Cube]/[板厚中心部Cube]が1.2以上、[表層部S]/[板厚中心部S]が0.8以下、より好ましくは、[表層部Cube]/[板厚中心部Cube]が1.3以上、[表層部S]/[板厚中心部S]が0.7以下とする。
On the other hand, the [surface layer portion S] is less than 10%, the [surface layer portion S] / [plate thickness center portion S] is 1.0 or more, and the [plate thickness center portion S] is too small. If the plate thickness center portion S] is too much, the strength decreases.
Here, in order to further improve the VDA bendability and strength, preferably, [surface layer portion Cube] / [plate thickness center portion Cube] is 1.2 or more, [surface layer portion S] / [plate thickness] The center portion S] is 0.8 or less, and more preferably, the [surface layer portion Cube] / [plate thickness center portion Cube] is 1.3 or more and the [surface layer portion S] / [plate thickness center portion S] is 0.7. The following.
 なお、これらのCube方位やS方位の関係を満たせば、他のCR方位、Brass方位、Cu方位、Goss方位 、Rotated-Goss方位、S方位、B/G方位、B/S方位、P方位などの他の方位の結晶粒が存在することは許容される。常法による製造限界からも、これらの他の方位の結晶粒を無くすことはできない。 If the relationship between the Cube orientation and S orientation is satisfied, other CR orientation, Brass orientation, Cu orientation, Goss orientation, Rotated-Goss orientation, S orientation, B / G orientation, B / S orientation, P orientation, etc. The presence of grains with other orientations is allowed. The crystal grains of these other orientations cannot be eliminated from the production limit by a conventional method.
 前記[表層部Cube]を増すためには、冷延板あるいは熱延板などの板の溶体化処理時に起こる再結晶での、圧延集合組織の残存量を低下させる必要がある。その目安として、前記[表層部S]を極力少なくする。圧延集合組織の残存量が多くなり、前記[表層部S]が多くなった場合には、自動車衝突時における衝撃吸収性(圧壊特性)が低下する。 In order to increase the [surface layer portion Cube], it is necessary to reduce the residual amount of the rolling texture in the recrystallization that occurs during the solution treatment of a cold-rolled plate or a hot-rolled plate. As a guide, the [surface layer portion S] is reduced as much as possible. When the remaining amount of the rolling texture increases and the [surface layer part S] increases, the impact absorbability (crushing characteristics) at the time of automobile collision decreases.
集合組織の測定:
 これら本発明で規定する平均結晶粒径や、各方位を有する結晶粒の面積率は、いずれもEBSP法によって測定する。より具体的に、溶体化処理後の冷延板や熱延板(T4材)の幅方向断面から、板の板厚の15%の深さまでの表層部と、板厚中心部とを各々採取して、機械研磨し、更に、バフ研磨に次いで電解研磨して、表面を調製した試料を用意し、SEMあるいはFESEMを用いて、EBSPによる、前記表層部と前記板厚中心部との、結晶方位測定並びに結晶粒径測定を各々行う。そして、この板の表面から板厚の15%の深さまでの表層部の[表層部Cube]と[表層部S]とを、また、板の板厚中心部における[板厚中心部Cube]と[板厚中心部S]とを各々測定する。
Texture measurement:
The average crystal grain size and the area ratio of crystal grains having each orientation defined in the present invention are all measured by the EBSP method. More specifically, the surface layer part from the width direction cross section of the cold-rolled sheet or hot-rolled sheet (T4 material) after solution treatment to a depth of 15% of the sheet thickness and the center part of the sheet thickness are sampled respectively. Then, a sample having a surface prepared by mechanical polishing and further by electrolytic polishing following buff polishing is prepared, and crystals of the surface layer portion and the plate thickness center portion by EBSP using SEM or FESEM Orientation measurement and crystal grain size measurement are performed, respectively. Then, [surface layer portion Cube] and [surface layer portion S] of the surface layer portion from the surface of the plate to a depth of 15% of the plate thickness, and [plate thickness center portion Cube] in the plate thickness center portion of the plate, [Thickness center portion S] is measured.
 EBSP測定・解析システムは、EBSP:TSL社製(OIM)あるいはOXFORD社製(CHANNEL5)を用いる。板の組織の測定部位は、通常のこの種組織の測定部位と同じく、この板の幅方向断面として、この板の幅方向断面の任意の箇所から採取した5個の測定試験片(5箇所の測定箇所)の、前記表層部の各測定値や板厚中央部の各測定値を、それぞれで平均化したものを、本発明で規定する平均結晶粒径や各方位を有する結晶粒の面積率とする。 The EBSP measurement / analysis system uses EBSP: manufactured by TSL (OIM) or OXFORD (CHANNEL5). The measurement site | part of the structure | tissue of a board is five measurement test pieces (5 place | parts) extract | collected from the arbitrary places of the width direction cross section of this board as a width direction cross section of this board similarly to the measurement site | part of this normal structure | tissue. (Measurement location), the average value of the crystal grains having the average crystal grain size and the respective orientations defined in the present invention, obtained by averaging the measurement values of the surface layer part and the measurement values of the central part of the plate thickness. And
 前記SEM/EBSP法は、集合組織の測定方法として汎用され、走査型電子顕微鏡(Scanning Electron Microscope:SEM)あるいは電界放出型走査電子顕微鏡(Field Emission Scanning Electron Microscope:FESEM)に、後方散乱電子回折像[EBSP Electron Back Scattering(Scattered) Pattern]システムを搭載した結晶方位解析法である。この測定方法は、他の集合組織の測定方法に比して、高分解能ゆえに高測定精度であり、板の同じ測定部位の平均結晶粒径も同時に高精度に測定できる利点がある。 The SEM / EBSP method is widely used as a texture measurement method, and is applied to a scanning electron microscope (Scanning Electron Microscope: SEM) or a field emission scanning electron microscope (Field Emission Scanning Electron Microscope: FESEM). This is a crystal orientation analysis method equipped with an [EBSP Electron Back Scattering (Scattered) Pattern] system. This measurement method has a high measurement accuracy because of its high resolution as compared with other texture measurement methods, and has an advantage that the average crystal grain size of the same measurement site of the plate can be simultaneously measured with high accuracy.
 SEM/EBSP法は、前記SEMあるいはFESEM(FE-SEM)の鏡筒内にセットしたAl合金板の試料に、電子線を照射してスクリーン上にEBSPを投影する。これを高感度カメラで撮影して、コンピュータに画像として取り込む。コンピュータでは、この画像を解析して、既知の結晶系を用いたシミュレーションによるパターンとの比較によって、結晶の方位が決定される。算出された結晶の各方位は3次元オイラー角として、位置座標(x、y)などとともに記録される。このプロセスが全測定点に対して自動的に行なわれるので、測定終了時には数万~数十万点の結晶方位データが得られる。これらSEMあるいはFESEMにEBSPシステムを搭載した結晶方位解析法の詳細は、神戸製鋼技報/Vol.52 No.2(Sep.2002)P66-70などに詳細に記載されている。 In the SEM / EBSP method, an EBSP is projected onto a screen by irradiating an electron beam onto a sample of an Al alloy plate set in a lens barrel of the SEM or FESEM (FE-SEM). This is taken with a high-sensitivity camera and captured as an image on a computer. In the computer, the orientation of the crystal is determined by analyzing this image and comparing it with a pattern obtained by simulation using a known crystal system. Each calculated orientation of the crystal is recorded as a three-dimensional Euler angle together with position coordinates (x, y) and the like. Since this process is automatically performed for all measurement points, tens of thousands to hundreds of thousands of crystal orientation data can be obtained at the end of measurement. Details of the crystal orientation analysis method in which the EBSP system is mounted on these SEM or FESEM are described in detail in Kobe Steel Technical Report / Vol. 52 No. 2 (Sep. 2002) P66-70.
 アルミニウム合金板の場合、通常は、以下に示す多くの方位因子「これら各方位を有する結晶粒」からなる集合組織を形成し、それらに応じた結晶面が存在する。一般に、アルミニウム合金の圧延板における集合組織は、主としてCube方位、Goss方位、Brass方位、S方位、およびCopper方位から構成される。これらの集合組織のでき方は、同じ結晶系の場合でも加工、熱処理方法によって異なり、圧延による板材の集合組織の場合は、圧延面と圧延方向で表されており、圧延面は{hkl}で表現され、圧延方向は<uvw>で表現される。かかる表現に基づき、各方位は下記の如く表現される。 In the case of an aluminum alloy plate, usually, a texture composed of many orientation factors “crystal grains having these respective orientations” shown below is formed, and there are crystal planes corresponding to them. In general, a texture in a rolled sheet of an aluminum alloy mainly includes a Cube orientation, a Goss orientation, a Brass orientation, an S orientation, and a Copper orientation. How these textures are formed differs depending on the processing and heat treatment methods even in the case of the same crystal system. In the case of a texture of a plate material by rolling, the rolling surface is represented by the rolling surface and the rolling direction, and the rolling surface is represented by {hkl}. Expressed and the rolling direction is expressed as <uvw>. Based on this expression, each direction is expressed as follows.
Cube方位 {001}<100>
Goss方位 {011}<100>
Brass方位(B方位) {011}<211>
Cu方位(Copper方位){112}<111>
S方位 {123}<634>
B/G方位 {011}<511>
B/S方位 {168}<211>
P方位 {011}<111>
Cube orientation {001} <100>
Goss orientation {011} <100>
Brass orientation (B orientation) {011} <211>
Cu orientation (Copper orientation) {112} <111>
S orientation {123} <634>
B / G direction {011} <511>
B / S orientation {168} <211>
P direction {011} <111>
 本発明においては、基本的に、これらの結晶面から±10°未満の方位のずれ(傾角)のものは同一の結晶面(方位因子)に属するものとする。また、隣り合う結晶粒の方位差(傾角)が5°以上の結晶粒の境界を結晶粒界と定義する。 In the present invention, basically, deviations (tilt angles) of orientation less than ± 10 ° from these crystal planes belong to the same crystal plane (orientation factor). Further, the boundary between crystal grains in which the orientation difference (tilt angle) between adjacent crystal grains is 5 ° or more is defined as a crystal grain boundary.
 そして、前記したSEMあるいはFESEMにEBSPシステムを搭載した結晶方位解析法を用いて、そして、この板の表面から板厚の15%の深さまでの表層部の[表層部Cube]と[表層部S]とを、また、板の板厚中心部における[板厚中心部Cube]と[板厚中心部S]とを、各々算出する。
 この際、上記のように記載したCube方位からP方位までの各結晶方位(全結晶方位)の合計の面積を100として、本発明で規定した各方位の面積率の算出を行なった。
Then, by using the crystal orientation analysis method in which the EBSP system is mounted on the SEM or FESEM, the surface layer portion [surface layer portion Cube] and [surface layer portion S from the surface of the plate to a depth of 15% of the plate thickness are used. And [plate thickness center portion Cube] and [plate thickness center portion S] at the plate thickness center portion of the plate, respectively.
Under the present circumstances, the area ratio of each orientation prescribed | regulated by this invention was computed by making the total area of each crystal orientation (all crystal orientations) from Cube orientation described above into P orientation into 100. FIG.
 なお、前記平均結晶粒径も、傾角が5°以上の粒界で測定、算出する。言い換えると、本発明では、±5°未満の方位のずれは同一の結晶粒に属するものと定義し、隣り合う結晶粒の方位差(傾角)が5°以上の結晶粒の境界を結晶粒界と定義した上で、平均結晶粒径を以下の式により算出した。平均結晶粒径=(Σx)/n(ここで、nは測定した結晶粒の数、xはそれぞれの結晶粒径を示す)。 The average crystal grain size is also measured and calculated at a grain boundary with an inclination angle of 5 ° or more. In other words, in the present invention, an orientation shift of less than ± 5 ° is defined as belonging to the same crystal grain, and a boundary between crystal grains having an orientation difference (tilt angle) of 5 ° or more between adjacent crystal grains is defined as a grain boundary. And the average crystal grain size was calculated by the following formula. Average crystal grain size = (Σx) / n (where n is the number of crystal grains measured and x is the respective crystal grain size).
(製造方法)
 本発明の7000系アルミニウム合金板は、鋳塊を均熱処理後に熱間圧延され、更に冷間圧延された冷延板であって、更に溶体化処理などの調質が施される、常法によって製造される。即ち、鋳造、均質化熱処理、熱間圧延の通常の各製造工程を経て製造され、板厚が2~10mm程度であるアルミニウム合金熱延板とされる。次いで、冷間圧延されて板厚が3mm以下の冷延板とされる。
(Production method)
The 7000 series aluminum alloy sheet of the present invention is a cold-rolled sheet obtained by subjecting an ingot to hot rolling after soaking and further cold rolling, and further subjected to tempering such as solution treatment. Manufactured. That is, an aluminum alloy hot rolled sheet having a thickness of about 2 to 10 mm is manufactured through normal manufacturing processes such as casting, homogenization heat treatment, and hot rolling. Subsequently, it is cold-rolled to obtain a cold-rolled sheet having a thickness of 3 mm or less.
 したがって、本発明の7000系アルミニウム合金板は、双ロール法などの薄板連続鋳造後に冷延して熱延を省略したり、温間圧延を行うような特殊な製造方法や圧延方法によっては製造しない。但し、本発明で規定する集合組織とするための均熱条件と溶体化処理条件とは、後述する通り、常法による工程とは、その条件が異なる。 Therefore, the 7000 series aluminum alloy plate of the present invention is not manufactured by a special manufacturing method or rolling method in which cold rolling is performed after thin sheet continuous casting such as a twin roll method to omit hot rolling or warm rolling is performed. . However, the soaking conditions and the solution treatment conditions for obtaining the texture defined in the present invention are different from those in the conventional process, as will be described later.
(溶解、鋳造冷却速度)
 先ず、溶解、鋳造工程では、上記7000系成分組成範囲内に溶解調整されたアルミニウム合金溶湯を、連続鋳造法、半連続鋳造法(DC鋳造法)等の通常の溶解鋳造法を適宜選択して鋳造する。
(Dissolution, casting cooling rate)
First, in the melting and casting process, an ordinary molten casting method such as a continuous casting method or a semi-continuous casting method (DC casting method) is appropriately selected for the aluminum alloy melt adjusted within the above-mentioned 7000-based component composition range. Cast.
(均質化熱処理)
 次いで、前記鋳造されたアルミニウム合金鋳塊に、熱間圧延に先立って、均質化熱処理を施す。この均質化熱処理(均熱処理)は、組織の均質化、すなわち、鋳塊組織中の結晶粒内の偏析をなくすことを目的とする。但し、この均熱処理は集合組織の形成にも大きく影響するので、本発明で規定する集合組織とするためには、この均熱処理を、通常の1回だけの均熱ではなく、2回均熱あるいは2段均熱とする。
(Homogenization heat treatment)
Next, the cast aluminum alloy ingot is subjected to a homogenization heat treatment prior to hot rolling. The purpose of this homogenization heat treatment (soaking) is to homogenize the structure, that is, eliminate segregation in crystal grains in the ingot structure. However, this soaking process has a great influence on the formation of the texture. Therefore, in order to obtain a texture as defined in the present invention, this soaking process is carried out twice soaking instead of the usual one soaking. Or it shall be two-stage soaking.
 2回均熱とは、1回目の均熱後に、一旦室温を含む200℃以下の温度まで冷却し、更に、再加熱し、その温度で一定時間維持した後に、熱延を開始する。これに対して、2段均熱とは、1回目の均熱後に冷却はするものの、200℃以下までは冷却せず、より高温で冷却を停止した上で、その温度で維持した後に、そのままの温度か、より高温に再加熱した上で熱延を開始する。 The second soaking means that after the first soaking, the steel is once cooled to a temperature of 200 ° C. or less including room temperature, reheated, and maintained at that temperature for a certain period of time, and then hot rolling is started. On the other hand, the two-stage soaking means cooling after the first soaking, but it is not cooled to 200 ° C. or lower, and after stopping the cooling at a higher temperature, the temperature is maintained as it is. The hot rolling is started after reheating to a higher temperature.
 1回目あるいは1段目の均熱条件は、400℃以上、融点未満の温度範囲で、2時間以上の保持時間の範囲から適宜選択される。 The first or first stage of soaking conditions is appropriately selected from a range of a holding time of 2 hours or more in a temperature range of 400 ° C. or higher and lower than the melting point.
 この1回目の均熱処理後に、2回均熱のために、一旦、室温を含む200℃以下まで冷却するか(2回均熱)、2段均熱のために、一旦、200℃よりも高温の温度まで冷却する(2段均熱)。この際の平均冷却速度は、2回均熱あるいは2段均熱とも共通して、30℃/hr以上、好ましくは40℃/hr以上の急冷とする。 After this first soaking process, it is once cooled to 200 ° C. or less including room temperature for soaking twice (twice soaking), and once higher than 200 ° C. for two-stage soaking. (2 stage soaking). In this case, the average cooling rate is set to 30 ° C./hr or more, preferably 40 ° C./hr or more, in common with the two-stage soaking or the two-stage soaking.
 このように冷却速度を増大させることで、冷却中の粗大な分散粒子の析出抑制し、それによって冷延時の圧延集合組織の発達を強める。これによって、溶体化処理時に起こる再結晶で、前記[表層部Cube]を発達させることができ、前記[表層部S]を適度な割合に制御することができる。 ∙ By increasing the cooling rate in this way, the precipitation of coarse dispersed particles during cooling is suppressed, thereby strengthening the development of the rolling texture during cold rolling. Accordingly, the [surface layer portion Cube] can be developed by recrystallization that occurs during the solution treatment, and the [surface layer portion S] can be controlled to an appropriate ratio.
 このような2回均熱あるいは2段均熱における、1回目の均熱処理後の冷却条件によって、後述する冷延条件、溶体化処理条件と合わせて、本発明で規定する集合組織とすることができる。
 一方、この冷却条件から外れるか、通常の1回の均熱処理では、後述する冷延条件、溶体化処理が好ましい範囲内で行われたとしてもて、本発明で規定する集合組織が得られない可能性が高くなる。
Depending on the cooling conditions after the first soaking in such two-stage soaking or two-stage soaking, the texture specified in the present invention can be made together with the cold rolling conditions and solution treatment conditions described later. it can.
On the other hand, the texture defined in the present invention cannot be obtained even if the cold rolling conditions and the solution treatment described below are performed within a preferable range in the normal one-time heat treatment, which is out of the cooling conditions. The possibility increases.
 2回目あるいは2段目の均熱条件は、熱延開始温度以上、500℃以下の温度範囲で2時間以上の保持時間の範囲から選択し、1回目の均熱、冷却後の鋳塊を再加熱し、熱延開始温度まで冷却するか、あるいは熱延開始温度まで再加熱してその近傍で保持すれば良い。また、1段目の均熱後の鋳塊を、熱延開始温度まで冷却して、その近傍で保持しても良い。これら、2回目あるいは2段目の均熱温度は、1回目あるいは1段目の均熱温度よりも低温とする方が好ましい。 The soaking condition for the second or second stage is selected from the range of the holding time of 2 hours or more in the temperature range of the hot rolling start temperature or higher and 500 ° C. or lower. It may be heated and cooled to the hot rolling start temperature, or reheated to the hot rolling start temperature and held in the vicinity thereof. Further, the ingot after soaking at the first stage may be cooled to the hot rolling start temperature and held in the vicinity thereof. The soaking temperature at the second or second stage is preferably lower than the soaking temperature at the first or first stage.
(熱間圧延)
 熱間圧延は、熱延開始温度が固相線温度を超える条件では、バーニングが起こるため熱延自体が困難となる。また、熱延開始温度が350℃未満では熱延時の荷重が高くなりすぎ、熱延自体が困難となる。したがって、熱延開始温度は350℃~固相線温度の範囲から選択して熱間圧延し、2~10mm程度の板厚の熱延板とする。この熱延板の冷間圧延前の焼鈍(荒鈍) は必ずしも必要ではないが実施しても良い。
(Hot rolling)
In the hot rolling, the hot rolling itself becomes difficult because burning occurs under conditions where the hot rolling start temperature exceeds the solidus temperature. On the other hand, when the hot rolling start temperature is less than 350 ° C., the load during hot rolling becomes too high, and the hot rolling itself becomes difficult. Therefore, the hot rolling start temperature is selected from the range of 350 ° C. to the solidus temperature and hot rolled to obtain a hot rolled sheet having a thickness of about 2 to 10 mm. Annealing (roughening) of the hot-rolled sheet before cold rolling is not always necessary, but may be performed.
(冷間圧延)
 冷間圧延では、上記熱延板を圧延して、自動車構造部材用としては1~5mm程度の所望の最終板厚の冷延板 (コイルも含む) に製作する。この際、本発明で規定する集合組織を形成させるために、熱延後で冷延前の荒鈍や、冷延途中での中間焼鈍を行う場合には、冷延率(総冷延率)を50%以上とする。冷延率が50%未満では、前記均熱処理や後述する溶体化処理を好ましい条件としても、本発明で規定する集合組織が得られない可能性が高くなる。一方、冷延率の上限は製造限界から決まり、概ね98%程度である。
 この冷延工程の回数は、熱延板の板厚と冷延板の最終板厚との関係で自由に選択され、この1回当たりの冷延工程における冷間圧延機への板(コイル)のパス回数も自由に選択される。
(Cold rolling)
In the cold rolling, the hot-rolled sheet is rolled to produce a cold-rolled sheet (including a coil) having a desired final thickness of about 1 to 5 mm for automobile structural members. Under the present circumstances, in order to form the texture prescribed | regulated by this invention, when performing the roughening before cold rolling after hot rolling and the intermediate annealing in the middle of cold rolling, a cold rolling rate (total cold rolling rate) Is 50% or more. When the cold rolling rate is less than 50%, there is a high possibility that the texture defined in the present invention cannot be obtained even if the soaking process or the solution treatment described below is a preferable condition. On the other hand, the upper limit of the cold rolling rate is determined by the production limit and is approximately 98%.
The number of cold rolling processes is freely selected according to the relationship between the thickness of the hot rolled sheet and the final thickness of the cold rolled sheet, and the sheet (coil) to the cold rolling mill in this cold rolling process. The number of passes can be freely selected.
 前記荒鈍や冷間圧延途中での中間焼鈍の温度は、380~500℃の範囲で、用いる連続炉やバッチ炉での通板条件に応じた適当な所要時間が選択される。中間焼鈍後の冷却は、ファンによる空冷などの強制冷却することが好ましい。連続焼鈍に関しては、後の溶体化処理での固溶確保の観点からは、到達温度は450℃以上が望ましい。バッチ焼鈍に関しては、冷却速度が遅いため、到達温度が高いと冷却中の析出物量が増大するので、到達温度は420℃以下が望ましい。 The temperature of the intermediate annealing during the roughing or cold rolling is in the range of 380 to 500 ° C., and an appropriate time is selected according to the sheet feeding conditions in the continuous furnace or batch furnace to be used. The cooling after the intermediate annealing is preferably forced cooling such as air cooling by a fan. Regarding continuous annealing, the ultimate temperature is desirably 450 ° C. or higher from the viewpoint of ensuring solid solution in the subsequent solution treatment. Regarding batch annealing, since the cooling rate is slow, if the ultimate temperature is high, the amount of precipitates during cooling increases. Therefore, the ultimate temperature is desirably 420 ° C. or lower.
(溶体化処理)
 冷間圧延後は調質として溶体化処理を行う。この溶体化処理については、通常の連続熱処理ラインによる加熱,冷却でよく、特に限定はされない。ただ、各元素の十分な固溶量を得ることや結晶粒の微細化のためには、450~550℃の溶体化処理温度とすることが望ましい。
(Solution treatment)
After cold rolling, solution treatment is performed as a tempering. The solution treatment is not particularly limited and may be heating and cooling using a normal continuous heat treatment line. However, in order to obtain a sufficient solid solution amount of each element or to refine crystal grains, it is desirable to set a solution treatment temperature of 450 to 550 ° C.
 溶体化処理時の加熱(昇温)速度は、3段階に分けることが望ましい。先ず、板の温度が300℃以下の範囲では、加熱(昇温)速度を、平均で0.001℃/s以上、10℃/s以下の範囲とする。次に、板の温度が300℃~450℃の範囲では、加熱(昇温)速度を、平均で10℃/s以上、100℃/s以下の範囲とする。更に、板の温度が450℃~固相線温度の範囲では、加熱(昇温)速度を、平均で0.001℃/s以上、10℃/s以下の範囲とする。 The heating (temperature increase) rate during the solution treatment is desirably divided into three stages. First, in the range where the temperature of the plate is 300 ° C. or less, the heating (temperature increase) rate is set to an average range of 0.001 ° C./s to 10 ° C./s. Next, when the temperature of the plate is in the range of 300 ° C. to 450 ° C., the heating (temperature increase) rate is set to an average range of 10 ° C./s to 100 ° C./s. Furthermore, when the temperature of the plate is in the range of 450 ° C. to the solidus temperature, the heating (temperature increase) rate is in the range of 0.001 ° C./s to 10 ° C./s on average.
 加熱(昇温)中の再結晶は、板の板厚中心部(中心部)よりも、板の表層部の方が、より低温で開始する。このため、板の温度が300℃以下の範囲を、前記低速で加熱(昇温)することで、前記[表層部Cube]を優先的に発達させることができ、前記[表層部Sを適度な割合に制御することができる。
 また、板の温度が300℃~450℃の範囲を、前記高速で加熱(昇温)することで、前記[板厚中心部S]を優先的に発達させることができ、再結晶粒の粗大化を抑制できる。
 そして、板の温度が450℃~固相線温度の範囲では、前記低速で加熱(昇温)することで、前記強化元素の固溶を確保することができる。
 なお、溶体化処理炉の設備能力の限界から、平均加熱速度は100℃/sを超えて大きくはできない。
Recrystallization during heating (temperature rise) starts at a lower temperature in the surface layer portion of the plate than in the center portion (center portion) of the plate thickness. For this reason, the [surface layer portion Cube] can be preferentially developed by heating (heating) the plate at a temperature of 300 ° C. or less at the low speed, and the [surface layer portion S is moderately formed. The ratio can be controlled.
Also, by heating (heating) the plate at a high temperature in the range of 300 ° C. to 450 ° C., the [plate thickness center S] can be preferentially developed, and the recrystallized grains are coarse. Can be suppressed.
When the temperature of the plate is in the range of 450 ° C. to the solidus temperature, solid solution of the strengthening element can be ensured by heating (heating) at the low speed.
The average heating rate cannot exceed 100 ° C./s because of the limit of the equipment capacity of the solution treatment furnace.
 溶体化処理後の平均冷却(降温)速度は、冷却中の粗大な分散粒子の析出抑制するために、10℃/s以上とすることが好ましい。このため、溶体化処理後の冷却は、ファンなどの空冷、ミスト、スプレー、浸漬等の水冷手段など、強制的な冷却手段を各々選択して用いるか、室温~100℃の水や湯に直接焼き入れることが好ましい。
 ちなみに、溶体化処理は基本的に1回のみであるが、室温時効硬化が進みすぎた場合などには、自動車部材などへの成形性の確保のため、溶体化処理を前記好ましい条件にて再度施して、この進みすぎた室温時効硬化を一旦キャンセルしても良い。
The average cooling (temperature decrease) rate after the solution treatment is preferably 10 ° C./s or more in order to suppress precipitation of coarse dispersed particles during cooling. For this reason, cooling after the solution treatment is performed by selecting and using a forced cooling means such as air cooling such as a fan, water cooling means such as mist, spraying, immersion, etc., or directly in water or hot water at room temperature to 100 ° C. It is preferable to quench.
By the way, the solution treatment is basically only once, but when the room temperature age hardening has progressed too much, the solution treatment is performed again under the above-mentioned preferable conditions in order to ensure the formability to automobile members and the like. Then, the room temperature age hardening that has progressed too much may be canceled once.
 そして、本発明のアルミニウム合金板は、素材として、バーリング加工、穴拡げ加工などを含む、プレス成形や加工が施された上で、自動車、自転車、鉄道車両などの構造部材とされる。また、成形性の確保の点で、これら構造部材に成形や加工された後で、別途、必要に応じて、人工時効硬化処理されて高強度化される。 The aluminum alloy plate of the present invention is used as a structural member for automobiles, bicycles, railway vehicles and the like after being subjected to press molding and processing including burring processing, hole expansion processing and the like as materials. Further, from the viewpoint of securing moldability, after being molded or processed into these structural members, an artificial age hardening treatment is separately performed to increase the strength as necessary.
(人工時効硬化処理)
 この人工時効硬化処理は、一般的な人工時効条件(T6、T7)で良く、温度や時間の条件は、所望の強度や素材の7000系アルミニウム合金板の強度、あるいは室温時効の進行程度などから自由に決定される。例示すると、1段の時効処理であれば、100~150℃での時効処理を12~36時間(過時効領域を含む)行う。また、2段の工程においては、1段目の熱処理温度が70~100℃の範囲で2時間以上、2段目の熱処理温度が100~170℃の範囲で5時間以上の範囲(過時効領域を含む)から選択する。
(Artificial age hardening treatment)
This artificial age hardening treatment may be performed under general artificial aging conditions (T6, T7), and the temperature and time conditions are based on the desired strength, the strength of the 7000 series aluminum alloy plate of the material, or the progress of aging at room temperature. It is decided freely. For example, in the case of a one-stage aging treatment, an aging treatment at 100 to 150 ° C. is performed for 12 to 36 hours (including an overaging region). In the two-stage process, the first-stage heat treatment temperature is in the range of 70 to 100 ° C. for 2 hours or longer, and the second-stage heat treatment temperature is in the range of 100 to 170 ° C. for five hours or longer (overaging region). Select from).
 下記表1に示す各成分組成の7000系アルミニウム合金の冷延板の集合組織を、表2のように製造条件を変えて種々変えたものについて、強度などの機械的な特性とVDA曲げ試験にて評価される衝撃吸収性(圧壊特性)を評価した。これらの結果を下記表3に示す。 Table 1 shows the composition of the 7000 series aluminum alloy cold-rolled sheet with various compositional changes, as shown in Table 2. The impact absorbability (crush properties) evaluated was evaluated. These results are shown in Table 3 below.
 冷延板の集合組織は、主として、表2に示すように、均熱条件と溶体化処理条件とを変えて制御した。具体的には、各例とも共通して、下記表1に示す各成分組成の7000系アルミニウム合金溶湯をDC鋳造し、得られた鋳塊を、表2に示す均熱条件と熱延開始温度にて熱間圧延を行い、3mm~25mmの板厚の熱延板を製造した。これらの熱延板を、各例とも共通して、500℃で30秒間保持後に、強制空冷を行う荒鈍(焼鈍)を施した後、表2に示す中間焼鈍条件にて、冷間圧延して、共通して2mmの板厚の冷延板を得た。ここで、表1中の各元素の含有量の表示において「-」としている表示は、その含有量が検出限界以下であることを示す。 The texture of the cold-rolled sheet was controlled mainly by changing the soaking condition and the solution treatment condition as shown in Table 2. Specifically, in common with each example, a 7000 series aluminum alloy molten metal having each component composition shown in Table 1 below is DC-cast, and the resulting ingot is subjected to soaking conditions and hot rolling start temperature shown in Table 2. Was hot rolled to produce a hot rolled sheet having a thickness of 3 to 25 mm. In common with each example, these hot-rolled sheets were held at 500 ° C. for 30 seconds, subjected to roughing (annealing) for forced air cooling, and then cold-rolled under the intermediate annealing conditions shown in Table 2. In common, a cold-rolled sheet having a thickness of 2 mm was obtained. Here, in the display of the content of each element in Table 1, “−” indicates that the content is below the detection limit.
 各例での冷延の冷延回数は3とし、各例とも共通して、各冷延工程1回当たりのパス回数は3とした。また、冷延工程間の中間焼鈍は、連続焼鈍炉の場合は昇温速度は200℃/min、冷却はファン空冷で行い、バッチ焼鈍炉の場合は昇降温速度は30℃/hrで行った。表2の中間焼鈍のうち、バッチ焼鈍を行った発明例2以外の例は、全て連続焼鈍である。 The number of cold rollings in each example was 3, and the number of passes per cold rolling process was 3 in common with each example. The intermediate annealing between the cold rolling steps was performed at a heating rate of 200 ° C./min in the case of a continuous annealing furnace, cooling was performed by fan air cooling, and the heating / lowering rate was 30 ° C./hr in the case of a batch annealing furnace. . Of the intermediate annealing in Table 2, all the examples other than Invention Example 2 in which batch annealing was performed are continuous annealing.
 これらの冷延板を、表2に示すように、平均昇温速度を温度範囲によって3段階に分けて制御した溶体化処理を行った。保持温度、保持時間、平均冷却速度も表2に示す条件で行い、T4材を得た。
 このT4材を室温で1週間時効させた後に、供試材を採取して、集合組織、微細析出物(参考)を調査し、また、後述する引張試験により、機械的な特性を調査した。これらの結果を各々表3に示す。
As shown in Table 2, these cold-rolled plates were subjected to a solution treatment in which the average heating rate was controlled in three stages according to the temperature range. Holding temperature, holding time, and average cooling rate were also performed under the conditions shown in Table 2 to obtain a T4 material.
The T4 material was aged at room temperature for 1 week, and then the sample material was collected to investigate the texture and fine precipitates (reference), and the mechanical properties were examined by a tensile test described later. These results are shown in Table 3, respectively.
(集合組織、平均結晶粒径)
 前記T4材の板状試験片の集合組織、平均結晶粒径の測定は、表層部及び板厚中心部の圧延面にてEBSD測定を行い、各方位成分粒の面積率及び結晶粒径(円相当直径)を求めた。
 具体的には、前記T4材の板状試験片の表層部及び板厚中心部の圧延面にて前記した測定方法により行った。測定は、TSL社製EBSP測定・解析システム〔OIM)を搭載した日本電子社製SEM(JEOL JSM 6500F)を用いた。各例とも、圧延方向表層部及び板厚中心部の任意の箇所から採取した各々の試験片5個について行い、これらの測定値を各々平均化した。各試験片の測定領域は、表層部は、酸化皮膜を除いた前記試験片表面から板厚方向に15%までの位置の圧延面、板厚中心部は板厚方向に50%の位置の圧延面において、1000μm×1000μmの領域とし、測定ステップ間隔も共通して1μmとした。
(Texture, average grain size)
The texture and average crystal grain size of the T4 material plate specimen are measured by EBSD on the rolling surface of the surface layer and the center of the plate thickness, and the area ratio and crystal grain size of each orientation component grain (circle) Equivalent diameter).
Specifically, the measurement was performed by the above-described measurement method on the surface layer portion of the plate-shaped test piece of the T4 material and the rolling surface of the plate thickness center portion. For the measurement, an SEM (JEOL JSM 6500F) manufactured by JEOL Ltd. equipped with an EBSP measurement / analysis system [OIM] manufactured by TSL was used. In each example, five test pieces collected from arbitrary portions of the surface layer portion in the rolling direction and the central portion of the plate thickness were measured, and these measured values were averaged. In the measurement area of each test piece, the surface layer portion is a rolled surface at a position up to 15% in the plate thickness direction from the surface of the test piece excluding the oxide film, and the plate thickness center portion is rolled at a position of 50% in the plate thickness direction. On the surface, the area was 1000 μm × 1000 μm, and the measurement step interval was also 1 μm in common.
(微細析出物)
 各例とも、参考として、前記T4材の板状試験片の表面から板厚中心である1/2t深さ部の断面を、倍率300000倍の透過型電子顕微鏡により観察し、結晶粒内の2.0~20nmのサイズの析出物の平均数密度(個/μm)を測定した。この観察を試験片5個について行い、結晶粒内の2.0~20nmのサイズの析出物の数密度を各々求めて、平均化(平均数密度と)したところ、各発明例ともに、2.0~20nmのサイズの析出物の数密度は平均で2~9×10個/μmの範囲であった。ここで、析出物のサイズは面積が等価な円の直径に換算して測定した。
(Fine precipitate)
In each example, as a reference, a cross section from the surface of the plate-shaped specimen of the T4 material to a 1 / 2t depth portion, which is the center of the plate thickness, was observed with a transmission electron microscope at a magnification of 300000 times. The average number density (pieces / μm 3 ) of precipitates having a size of 0.0 to 20 nm was measured. This observation was performed on five test pieces, and the number density of precipitates having a size of 2.0 to 20 nm in the crystal grains was obtained and averaged (referred to as the average number density). The number density of precipitates having a size of 20 nm was in the range of 2 to 9 × 10 4 pieces / μm 3 on average. Here, the size of the precipitate was measured in terms of the diameter of a circle having an equivalent area.
 また、前記T4材を室温で1週間時効させた後に、構造部材への成形加工後の人工時効硬化処理を模擬して、T6処理として、前記T4材を、90℃×3hr+140℃×8hrの2段階の共通する条件で、人工時効硬化処理を行い、T6材とした。こうして得られたT6材のアルミニウム合金板の中央部から板状試験片を採取して、機械的特性や耐食性を以下のようにして調査した。これらの結果も各々表3に示す。 Further, after aging the T4 material at room temperature for one week, an artificial age hardening treatment after forming the structural member was simulated, and the T4 material was subjected to 90 ° C. × 3 hr + 140 ° C. × 8 hr 2 Under the conditions common to the stages, artificial age hardening treatment was performed to obtain a T6 material. A plate-like test piece was collected from the center portion of the aluminum alloy plate of T6 thus obtained, and the mechanical properties and corrosion resistance were investigated as follows. These results are also shown in Table 3.
(機械的特性)
 各例とも、前記T6材あるいは前記T4材の板状試験片をJIS5号試験片に加工し、圧延方向に対して、引張方向が平行となるように室温引張試験を行い、引張強度(MPa)、0.2%耐力(MPa)を測定した。室温引張り試験はJIS2241(1980)に基づき、室温20℃で試験を行い、評点間距離50mmで引張速度5mm/分、試験片が破断するまで一定の速度で行った。
(Mechanical properties)
In each example, the plate test piece of the T6 material or the T4 material was processed into a JIS No. 5 test piece, and a room temperature tensile test was performed so that the tensile direction was parallel to the rolling direction, and the tensile strength (MPa). 0.2% proof stress (MPa) was measured. The room temperature tensile test was performed at a room temperature of 20 ° C. based on JIS2241 (1980), and was performed at a constant speed until the test piece broke at a distance of 50 mm between the ratings and a tensile speed of 5 mm / min.
(衝撃吸収性)
 衝撃吸収性を評価する曲げ試験は、VDA曲げ試験として、ドイツ自動車工業会(VDA)の規格の中の「VDA238-100Plate bending test for metallic materials」に従って実施した。この試験方法を、図1に斜視図で示す。
 先ず、前記T6材の板状試験片を、ロールギャップを設けて、互いに平行に配置した2個のロール上に、図1に点線で示すように、水平で左右均等の長さに載置する。
 具体的には、前記T6材の板状試験片を、その圧延方向と、上方に垂直に立てて配置した板状の押し曲げ治具の延在方向とが、互いに直角になるように、ロールギャップ中央にその中央部が位置するよう、2個のロール上に、水平で左右均等の長さに載置する。
 そして、上方から前記押し曲げ治具を板状試験片の中央部に押し当てて荷重を負荷し、この板状試験片を前記狭いロールギャップに向けて押し曲げ(突き曲げ)て、曲げ変形した板状試験片中央部を前記狭いロールギャップ内に押し込む。
(Shock absorption)
The bending test for evaluating impact absorbability was performed as a VDA bending test in accordance with “VDA238-100 Plate Bending Test for Metallic Materials” in the standards of the German Automobile Manufacturers Association (VDA). This test method is shown in perspective view in FIG.
First, the plate-like test piece of the T6 material is placed on two rolls arranged parallel to each other with a roll gap, as shown by dotted lines in FIG. .
Specifically, the T6 material plate-shaped test piece is rolled so that the rolling direction and the extending direction of the plate-shaped pushing and bending jig arranged vertically upright are perpendicular to each other. It is placed on two rolls horizontally and equally in the left and right so that the central part is located in the center of the gap.
Then, the pressing and bending jig is pressed against the center of the plate-shaped test piece from above to apply a load, and the plate-shaped test piece is bent toward the narrow roll gap (bending) to bend and deform. The center part of the plate-shaped test piece is pushed into the narrow roll gap.
 この際に、上方からの押し曲げ治具からの荷重Fが最大となる時の板状試験片の中央部の曲げ外側の角度を曲げ角度(°)として測定して、その曲げ角度の大きさで衝撃吸収性を評価する。この曲げ角度が大きいほど、板状試験片は、途中で圧壊せずに、曲げ変形が持続しており、衝撃吸収性(圧壊特性)が高い。 At this time, the angle of the bending outside of the center part of the plate-like test piece when the load F from the pushing bending jig from the maximum is measured as a bending angle (°), and the magnitude of the bending angle. Evaluate the shock absorption. The larger the bending angle, the more the plate-like test piece is not crushed in the middle, the bending deformation is continued, and the shock absorption (crushing property) is higher.
 このVDA曲げ試験の試験条件として、図1に記載した記号を用いて示すと、板状試験片は幅b:60mm×長さl:60mmの正方形形状とし、2個のロール直径Dは各々30mm、ロールギャップLは板状試験片板厚の2.0倍の4mmとした。sは荷重Fが最大となる時の板状試験片中央部のロールギャップ内への押し込み深さである。
 また、板状の押し曲げ治具は、図1に示すように、板状試験片の中央部に押し当たる、下端側の辺が、その先端(下端)の半径が0.2mmφとなるように尖ったテーパ状とされている。
 上記曲げ試験は、各例とも板状試験片3枚ずつ(3回)行い、曲げ角度(°)はこれらの平均値を採用した。
As test conditions for this VDA bending test, the symbols shown in FIG. 1 are used to indicate that the plate-shaped test piece has a square shape of width b: 60 mm × length l: 60 mm, and each of the two roll diameters D is 30 mm. The roll gap L was 4 mm, which is 2.0 times the plate thickness of the plate-shaped test piece. s is the depth of intrusion into the roll gap at the center of the plate-like test piece when the load F is maximum.
In addition, as shown in FIG. 1, the plate-like pushing / bending jig presses against the center portion of the plate-like test piece so that the lower end side has a radius of 0.2 mmφ at the tip (lower end). It has a sharp tapered shape.
In each example, the above bending test was carried out by three plate-like test pieces (three times), and the average value of the bending angles (°) was adopted.
(粒界腐食感受性)
 耐SCC性の評価にもつながる耐食性評価として、旧JIS-W1103の規定に準じた粒界腐食感受性試験を、前記人工時効硬化処理後の板状試験片(試験片3個)に対して行った。
 試験条件は、試験片を硝酸水溶液(30質量%)に室温で1分間浸漬した後、水酸化ナトリウム水溶液(5質量%)に40℃で20秒浸漬した後、硝酸水溶液(30質量%)に室温で1分間浸漬することによって試験片の表面を洗浄した。その後、塩化ナトリウム水溶液(5質量%)に浸漬した状態で、1mA/cmの電流密度の電流を24時間流した後、試料を引き上げ、その後、試験片の断面を切断・研磨し、光学顕微鏡を用いて、試料表面からの腐食深さを測定した。倍率は×100とし、腐食深さが200μm以下までを軽微な腐食として「○」と評価した。また、200μmを超える場合を大きな腐食として「×」と評価した。
(Intergranular corrosion sensitivity)
As corrosion resistance evaluation that leads to evaluation of SCC resistance, a grain boundary corrosion susceptibility test in accordance with the provisions of the former JIS-W1103 was performed on the plate-shaped test pieces (three test pieces) after the artificial age hardening treatment. .
The test condition was that the test piece was immersed in an aqueous nitric acid solution (30% by mass) for 1 minute at room temperature, then immersed in an aqueous sodium hydroxide solution (5% by mass) at 40 ° C. for 20 seconds, and then immersed in an aqueous nitric acid solution (30% by mass). The surface of the test piece was cleaned by immersion for 1 minute at room temperature. Thereafter, a current having a current density of 1 mA / cm 2 was allowed to flow for 24 hours in a state immersed in an aqueous sodium chloride solution (5% by mass), and then the sample was pulled up, and then the cross section of the test piece was cut and polished. Was used to measure the depth of corrosion from the sample surface. The magnification was x100, and a corrosion depth of 200 μm or less was evaluated as “◯” as minor corrosion. Moreover, the case where it exceeded 200 micrometers was evaluated as "x" as big corrosion.
 表1~3から明らかなように、各発明例は、本発明アルミニウム合金組成範囲内であり、前記した好ましい均熱処理条件と冷延条件の範囲内で製造されている。この結果、T4材の組織として、この板の表面から板厚の15%の深さまでの表層部の平均結晶粒径が40μm以下の等軸な再結晶組織であるとともに、前記[表層部Cube]が10%以上で、かつ、前記[表層部S]が10%以上、40%以下である。また、前記[表層部Cube]/[板厚中心部Cube]が1.0を超えているとともに、前記[表層部S]/[板厚中心部S]が1.0未満である。 As is apparent from Tables 1 to 3, each of the inventive examples is within the composition range of the aluminum alloy of the present invention, and is manufactured within the range of the preferred soaking conditions and cold rolling conditions described above. As a result, the structure of the T4 material is an equiaxed recrystallized structure in which the average crystal grain size of the surface layer portion from the surface of the plate to a depth of 15% of the plate thickness is 40 μm or less, and the [surface layer portion Cube] Is 10% or more, and the [surface layer part S] is 10% or more and 40% or less. Further, the [surface layer portion Cube] / [plate thickness center portion Cube] exceeds 1.0 and the [surface layer portion S] / [plate thickness center portion S] is less than 1.0.
 この結果、T6材の0.2%耐力が358~391MPaの強度レベルでは、VDA曲げ角度が67~55°の高いレベル、0.2%耐力が425~446MPaの強度レベルでも、VDA曲げ角度が44~40°の高いレベルを有して、強度と衝撃吸収性(圧壊特性)とを兼備している。また、耐食性にも優れている。 As a result, when the T6 material has a 0.2% proof strength of 358 to 391 MPa, the VDA bending angle is 67 to 55 °, and the 0.2% proof strength is 425 to 446 MPa. It has a high level of 44 to 40 °, and has both strength and shock absorption (crushing properties). It also has excellent corrosion resistance.
 ちなみに、表2、3の発明例1と2は、必要な強度を得るために、言い換えると、強度を制御するために、Mg、Znの各含有量を互いにバランスさせている好例である。発明例2は、表1の通り、発明例1よりZn含有量が少ないが、表3のように、発明例1より0.2%耐力が高くなっている。これは、発明例2が、Znの含有量が少ない分、Mg、Znの各含有量を互いにバランスさせ、発明例1よりMgの含有量を多く制御して強度を確保しているからである。一方、発明例1は、Znの含有量は多いが、Mg、Znの各含有量を互いにバランスさせて、発明例2よりMgの含有量を少なくし、0.2%耐力を低く制御している。 Incidentally, Invention Examples 1 and 2 in Tables 2 and 3 are good examples in which the contents of Mg and Zn are balanced with each other to obtain the required strength, in other words, to control the strength. Inventive Example 2 has a Zn content less than Inventive Example 1 as shown in Table 1, but as shown in Table 3, the 0.2% yield strength is higher than Inventive Example 1. This is because Invention Example 2 balances the contents of Mg and Zn with each other due to the low Zn content, and controls the Mg content more than Invention Example 1 to ensure strength. . On the other hand, Inventive Example 1 has a large Zn content, but the Mg and Zn contents are balanced with each other to reduce the Mg content and control the 0.2% proof stress to be lower than Inventive Example 2. Yes.
 一方、表2、3の比較例は、合金組成が、表1の通り、本発明範囲から外れるか、合金組成は本発明範囲内であるものの、前記した好ましい均熱処理条件と冷延条件の範囲からはずれて、各々製造されている。この結果、所望の集合組織を得られないか、得られていたとしても、強度の割にVDA曲げ角度が低い。 On the other hand, in the comparative examples of Tables 2 and 3, the alloy composition is not within the scope of the present invention as shown in Table 1, or the alloy composition is within the scope of the present invention, but the ranges of the preferred soaking conditions and cold rolling conditions described above. Each is manufactured. As a result, even if the desired texture cannot be obtained or obtained, the VDA bending angle is low for the strength.
 比較例9~15は、表1の発明例と同じ合金例1、3を用いている。しかし、これらの比較例は、表2に示す通り、1回のみの均熱(比較例10)、1回目の均熱後の冷却速度が遅い(比較例10~12)、冷延率が低い(比較例9、10)、溶体化処理の3段階の各温度範囲での各平均昇温速度が外れる(比較例9、11、12、13、14、15)など、製造条件が好ましい条件を外れている。
 このため、これら比較例は、T4材の組織として、この板の表面から板厚の15%の深さまでの表層部の平均結晶粒径が40μm以下の等軸な再結晶組織であるものの、前記[表層部Cube]が10%未満か(比較例9)、前記[表層部Cube]/[板厚中心部Cube]が1.0以下か(比較例9~11、13、15)、前記[表層部S]/[板厚中心部S]が1.0以上である(比較例9~15)。
 この結果、これら比較例は、T6材の0.2%耐力が346~375MPaの強度レベルでは、VDA曲げ角度が42~37°の低いレベルでしかなく、前記発明例の同程度の強度レベルでのVDA曲げ角度のレベルに比して著しく低く、強度と衝撃吸収性(圧壊特性)とを兼備できていないことが分かる。
Comparative examples 9 to 15 use the same alloy examples 1 and 3 as the invention examples of Table 1. However, as shown in Table 2, these comparative examples have only one soaking (Comparative Example 10), the cooling rate after the first soaking is slow (Comparative Examples 10 to 12), and the cold rolling rate is low. (Comparative Examples 9 and 10), conditions in which manufacturing conditions are preferable, such as each average temperature increase rate in each temperature range of the three stages of solution treatment (Comparative Examples 9, 11, 12, 13, 14, 15) It is off.
For this reason, although these comparative examples are the structure of T4 material, although the average crystal grain size of the surface layer portion from the surface of this plate to the depth of 15% of the plate thickness is an equiaxed recrystallized structure of 40 μm or less, Whether the [surface layer portion Cube] is less than 10% (Comparative Example 9), or the [surface layer portion Cube] / [plate thickness center portion Cube] is 1.0 or less (Comparative Examples 9 to 11, 13, 15), Surface layer portion S] / [plate thickness center portion S] is 1.0 or more (Comparative Examples 9 to 15).
As a result, in these comparative examples, when the 0.2% proof stress of the T6 material is a strength level of 346 to 375 MPa, the VDA bending angle is only a low level of 42 to 37 °, which is the same strength level as the above invention example. It can be seen that it is remarkably lower than the level of the VDA bending angle, and does not have both strength and shock absorption (crush characteristics).
 比較例16~23は、比較例19、20を除き、好ましい条件範囲で製造しているものの、表1の合金番号9~16を用いており、Znが少ない(合金番号9)、Mgが少ない(合金番号10)、Cu、Zr、Mn、Cr、Scが多すぎる(合金番号11~16)など、各々本発明の組成範囲を外れている。
 加えて、比較例19は1回のみの均熱であり、比較例19、20は冷延率が低く、比較例20は溶体化処理の3段階の各温度範囲での各平均昇温速度や溶体化処理後の平均冷却速度が好ましい条件も外れている。
 このため、これら比較例は、表3に示す通り、T4材の組織として、この板の表面から板厚の15%の深さまでの表層部の平均結晶粒径が40μmを超えるか(比較例16~18)、前記[表層部Cube]が10%未満か(比較例18~23)、前記[表層部Cube]/[板厚中心部Cube]が1.0以下か(比較例16、18~23)、前記[表層部S]/[板厚中心部S]が1.0以上である(比較例16~23)。
 この結果、これら比較例は、T6材の0.2%耐力が319~370MPaの強度レベルでも、VDA曲げ角度が53~32°の低いレベルしかなく、0.2%耐力が428~471MPaの強度レベルでは、VDA曲げ角度が38~32°の低いレベルで、前記発明例の同程度の強度レベルでのVDA曲げ角度のレベルに比して著しく低く、強度と衝撃吸収性(圧壊特性)とを兼備できていないことが分かる。
 また、比較例16は強度が低すぎ、比較例18は耐食性が低すぎる。
Comparative Examples 16 to 23 are manufactured in a preferable condition range except for Comparative Examples 19 and 20, but use Alloy Nos. 9 to 16 in Table 1 and have a small amount of Zn (Alloy No. 9) and a small amount of Mg. (Alloy No. 10), Cu, Zr, Mn, Cr, and Sc are too much (Alloy Nos. 11 to 16).
In addition, Comparative Example 19 is only one-time soaking, Comparative Examples 19 and 20 have a low cold rolling rate, and Comparative Example 20 has an average rate of temperature increase in each temperature range of the three stages of solution treatment. The preferable condition for the average cooling rate after the solution treatment is also out of the range.
Therefore, in these comparative examples, as shown in Table 3, as the structure of the T4 material, whether the average crystal grain size of the surface layer portion from the surface of the plate to a depth of 15% of the plate thickness exceeds 40 μm (Comparative Example 16 To 18), whether the [surface layer portion Cube] is less than 10% (Comparative Examples 18 to 23), or whether the [surface layer portion Cube] / [plate thickness center portion Cube] is 1.0 or less (Comparative Examples 16, 18 to 23), the [surface layer portion S] / [plate thickness center portion S] is 1.0 or more (Comparative Examples 16 to 23).
As a result, in these comparative examples, even when the 0.2% proof stress of the T6 material is a strength level of 319 to 370 MPa, the VDA bending angle is only a low level of 53 to 32 °, and the 0.2% proof stress is a strength of 428 to 471 MPa. In terms of level, the VDA bending angle is a low level of 38 to 32 °, which is significantly lower than the level of the VDA bending angle at the same strength level as in the above-described invention example, and the strength and shock absorption (crushing characteristics) are reduced. You can see that they are not combined.
Further, Comparative Example 16 has too low strength, and Comparative Example 18 has too low corrosion resistance.
 以上の結果から、本発明アルミニウム合金板がVDA曲げ試験にて評価される衝撃吸収性(圧壊特性)、高強度、そして耐食性を各々兼備するための、本発明の各要件の臨界的な意義が裏付けられる。 From the above results, the critical significance of each requirement of the present invention is that the aluminum alloy plate of the present invention has both impact absorbability (crushing property), high strength, and corrosion resistance evaluated in the VDA bending test. It is supported.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
 本発明を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明らかである。
 本出願は、2015年3月4日出願の日本特許出願(特願2015-042565)に基づくものであり、その内容はここに参照として取り込まれる。
Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on March 4, 2015 (Japanese Patent Application No. 2015-042565), the contents of which are incorporated herein by reference.
 以上説明したように、本発明は、常法の圧延によって製造され、強度を低下させずに、自動車の衝突時における衝撃吸収性(圧壊特性)を向上させた、7000系アルミニウム合金板を提供できる。したがって、本発明は軽量化に寄与する、自動車、自転車、鉄道車両などの構造部材に好適である。 As described above, the present invention can provide a 7000 series aluminum alloy plate that is manufactured by conventional rolling and has improved impact absorption (crushing characteristics) at the time of automobile collision without reducing strength. . Therefore, the present invention is suitable for structural members such as automobiles, bicycles, and railway vehicles that contribute to weight reduction.

Claims (3)

  1.  質量%で、Zn:2.0~9.0%、Mg:0.5~4.5%を各々含有するとともに、Cu:0.5%以下(但し0%を含む)、Zr:0.15%以下(但し0%を含む)、Mn:0.2%以下(但し0%を含む)、Cr:0.15%以下(但し0%を含む)、Sc:0.05%以下(但し0%を含む)に各々規制し、残部がAl及び不可避的不純物からなるアルミニウム合金板であって、この板の表面から板厚の15%の深さまでの表層部の結晶粒のうち、Cube方位を有する結晶粒の面積率を[表層部Cube]、S方位を有する結晶粒の面積率を[表層部S]と各々するとともに、前記板の板厚中心部における結晶粒のうち、Cube方位を有する結晶粒の面積率を[板厚中心部Cube]、S方位を有する結晶粒の面積率を[板厚中心部S]と各々した時、前記表層部は、平均結晶粒径が40μm以下の等軸な再結晶組織であるとともに、前記[表層部Cube]が10%以上で、かつ、前記[表層部S]が10%以上、40%以下であり、かつ、前記[表層部Cube]の前記[板厚中心部Cube]に対する割合である[表層部Cube]/[板厚中心部Cube]が1.0を超えているとともに、前記[表層部S]の前記[板厚中心部S]に対する割合である[表層部S]/[板厚中心部S]が1.0未満であるような、前記表層部と前記板厚中心部とが異なる集合組織を有することを特徴とするアルミニウム合金板。 In mass%, Zn: 2.0 to 9.0%, Mg: 0.5 to 4.5%, respectively, Cu: 0.5% or less (including 0%), Zr: 0.0. 15% or less (including 0%), Mn: 0.2% or less (including 0%), Cr: 0.15% or less (including 0%), Sc: 0.05% or less (however, 0% (including 0%), and the balance is an aluminum alloy plate made of Al and inevitable impurities, and among the crystal grains in the surface layer portion from the surface of the plate to a depth of 15% of the plate thickness, the Cube orientation The surface area ratio of the crystal grains having the surface ratio is [surface layer portion Cube], the area ratio of the crystal grains having the S orientation is [surface layer section S], and among the crystal grains in the center portion of the plate thickness, the Cube orientation is The area ratio of crystal grains having [plate thickness center portion Cube] and the area ratio of crystal grains having S orientation [ When the thickness center portion S] is used, the surface layer portion has an equiaxed recrystallized structure having an average crystal grain size of 40 μm or less, the surface layer portion Cube is 10% or more, and the surface layer Part S] is 10% or more and 40% or less, and [surface layer part Cube] / [sheet thickness center part Cube], which is the ratio of the [surface layer part Cube] to the [sheet thickness center part Cube], is 1. And [surface layer portion S] / [plate thickness center portion S] which is a ratio of the [surface layer portion S] to the [plate thickness center portion S] is less than 1.0, The aluminum alloy plate characterized in that the surface layer portion and the plate thickness center portion have different textures.
  2.  前記アルミニウム合金板が、更に、下記(a)及び(b)の少なくとも一方を含む請求項1に記載のアルミニウム合金板。
    (a)質量%で、Ag:0.01~0.2%、Sn:0.001~0.1%の1種又は2種
    (b)質量%で、Ti:0.001~0.1%
    The aluminum alloy plate according to claim 1, wherein the aluminum alloy plate further includes at least one of the following (a) and (b).
    (A) Mass%, Ag: 0.01 to 0.2%, Sn: 0.001 to 0.1%, or 1 type or 2 (b) Mass%, Ti: 0.001 to 0.1 %
  3.  前記アルミニウム合金板が衝撃吸収部材用である請求項1または2に記載のアルミニウム合金板。 The aluminum alloy plate according to claim 1 or 2, wherein the aluminum alloy plate is for an impact absorbing member.
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