JP4164206B2 - High-strength, high-formability aluminum alloy sheet with excellent recrystallization grain refinement during high-temperature annealing - Google Patents

High-strength, high-formability aluminum alloy sheet with excellent recrystallization grain refinement during high-temperature annealing Download PDF

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JP4164206B2
JP4164206B2 JP27429399A JP27429399A JP4164206B2 JP 4164206 B2 JP4164206 B2 JP 4164206B2 JP 27429399 A JP27429399 A JP 27429399A JP 27429399 A JP27429399 A JP 27429399A JP 4164206 B2 JP4164206 B2 JP 4164206B2
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annealing
aluminum alloy
strength
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JP2001098338A (en
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一徳 小林
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株式会社神戸製鋼所
古河スカイ株式会社
住友軽金属工業株式会社
日本軽金属株式会社
三菱アルミニウム株式会社
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Description

【0001】
【発明の属する技術分野】
本発明は、高温焼鈍時の再結晶粒微細化に優れた高強度高成形性アルミニウム合金板(以下、アルミニウムを単にAlと言う)に関するものである。
【0002】
【従来の技術】
鉄道車両、航空機、船舶、自動車、自動二輪、自転車等の輸送機、或いは圧力容器やタンク等の化学プラント、更には建築物や構造物等の構造部材や構造部品として、主として、AA乃至JIS 5052、5056、5082、5182、5083、5086等の、Mgを3.5% (質量% 、以下同じ) 以上を含むAl-Mg 系乃至5000系Al合金板が使用されている。これらMg含有量の多いAl-Mg 系Al合金板は、優れた強度や成形性を持ち、溶接性も良好であるため、溶接構造部材として汎用されている。
【0003】
このAl-Mg 系Al合金板は、周知の通り、常法により、鋳塊を均質化熱処理後、熱間圧延および冷間圧延により所定の板厚とした後、再結晶焼鈍を行ってAl合金板とされる。そして、このAl-Mg 系Al合金板の再結晶粒度は、通常20〜30μm のレベルである。
【0004】
これに対し、近年、このAl-Mg 系Al合金板の強度や成形性の更なる向上のために、再結晶粒度をより微細化することが研究されている。例えば、特願平11-268599 号などでは、最大で7.0%までのMgを含有させるとともに、Fe:0.1〜2.0%、Cr:0.05 〜0.5%、Zr:0.05 〜0.2%の一種または二種以上を含むAl-Mg 系Al合金について、冷間圧延において90% 以上の大圧下を加えて、再結晶焼鈍後の再結晶粒度を5 μm 以下の超微細粒とすることが提案されている。
【0005】
この技術は、Mg含有量を極端に多くするとともに、冷間圧延において大圧下を加えて、再結晶の核生成サイトとなる転位やFeを含む化合物粒子を増加させ、更に、Mn、Cr、Zrなどの分散粒子 (析出物) により、粒界の移動による再結晶粒の粗大成長を抑制しようとするものである。
【0006】
【発明が解決しようとする課題】
この再結晶粒微細化技術により、実際に、再結晶焼鈍後の再結晶粒度を5 μm 以下の超微細粒としたAl-Mg 系Al合金板の製造が可能となる。しかし、この再結晶粒微細化技術では、再結晶粒度を5 μm 以下とするために、再結晶焼鈍温度を350 ℃以下の低温とする必要がある。言い換えると、再結晶焼鈍温度を350 ℃を越える温度とした場合、再結晶粒が粗大化して、粒度を5 μm 以下とすることができなくなる。
【0007】
この再結晶粒微細化技術では、Mg含有量を極端に多くするとともに、冷間圧延において大圧下を加えているため、Al合金板の加工硬化量が極端に大きい。このため、再結晶焼鈍の際の温度が低温側に制約されると、焼きなましが不十分となる場合が生じ、前記各種用途で要求される伸びや絞り高さなどの成形性を満足できない可能性がある。
【0008】
この点、前記特願平11-268599 号でも、最終焼鈍温度を350 ℃以下の低温とする必要があることが明記され、その実施例では、この発明範囲内の、Mn:0.2% 、Fe:1.26%、Cr:0.15%を含むAl-Mg 系Al合金板について、最終焼鈍温度を420 ℃とした場合に、350 ℃未満の焼鈍温度の発明例に比して、再結晶粒度が5 μm を越えて粗大化し、Al合金板の成形性などの特性が低下していることが記載されている。
【0009】
従って、この再結晶粒微細化技術では、再結晶焼鈍後の再結晶粒度を5 μm 以下の超微細粒とするためは、焼鈍温度を350 ℃未満の低温とする必要がある。このため、用途によっては、強度が高すぎる乃至Al-Mg 系Al合金板特有のSSマークが生じるなど、要求される成形性を満足できない場合が生じ、Al合金板の用途が制約される可能性がある。
【0010】
本発明はこの様な事情に着目してなされたものであって、その目的は、高温の再結晶焼鈍を行っても、焼鈍後の再結晶粒度を5 μm 以下の超微細粒とすることが可能なAl-Mg 系Al合金板を提供しようとするものである。
【0011】
【課題を解決するための手段】
この目的を達成するために、本発明Al-Mg 系Al合金板の要旨は、Mg:3.0〜10.0% (質量% 、以下同じ) 、Mn:0.1〜1.5%を含み残部Alおよび不可避的不純物からなり、冷間圧延において90% 以上の圧下が加えられるとともに、最終焼鈍後の再結晶粒度が5 μm 以下である、Al-Mg 系Al合金板であって、組織内に分散析出するAl-Mn 系化合物の最大長さを500nm 以下とすることである。
【0012】
また、選択的添加元素を加えた本発明Al合金板の別の態様として、前記Al合金板が、更に、Fe:0.1〜2.0%、Cr:0.05 〜0.2%、Zr:0.05 〜0.2%の一種または二種以上を含む (請求項2 に対応) 、および/ または、Ti:0.001〜0.1%、B:1 〜300ppmの一種または二種を含む (請求項3 に対応) を含むことである。
【0013】
そして、本発明Al合金板の好ましい用途としては、焼鈍の温度が350 ℃を越える高温の最終焼鈍に用いられることである (請求項4 に対応) 。
【0014】
本発明では、前記特願平11-268599 号の技術思想を前提としている。即ち、Mg含有量を多くするとともに、冷間圧延において大圧下を加えて、再結晶の核生成サイトとなる転位を増加させ、加えて核生成サイトとなるFeの化合物粒子( 晶出物) を増加させ、更に、Mn、Cr、Zrなどの化合物粒子 (析出物) により、粒界の移動による再結晶粒の粗大成長を抑制し、最終焼鈍後の再結晶粒度を5 μm 以下とする技術思想は、前記特願平11-268599 号と同じである。したがって、本発明では、後述するMnの必須添加と、Al合金板が90% 以上の大きな圧下率で冷間圧延されることを前提とする。
【0015】
しかし、本発明者らは、まず、粒界の移動による再結晶粒の粗大成長を抑制すべき、Mn、Cr、Zrなどの化合物粒子乃至分散粒子 (析出物) に、前記350 ℃以上の高温の再結晶焼鈍時には、350 ℃未満の低温の再結晶焼鈍時には無い、再結晶粒度の微細化 (粗大化防止) 効果の差が生じることを知見した。
【0016】
即ち、Mn、Cr、Zrなどの化合物粒子は、周知の通り、前記Al-Mg 系Al合金鋳塊の均質化熱処理時に生じるものである。ただ、各々の含有量や鋳造条件および均質化熱処理時の条件によって、特に、化合物粒子の大きさや形状が異なり、これが、350 ℃以上の高温の再結晶焼鈍時の再結晶粒度の微細化 (粗大化防止) 効果の差につながる。
【0017】
特に、Cr、Zrなどの化合物粒子は、Mnの化合物粒子の大きさに比して、通常は小さい。したがって、通常、結晶粒の成長抑制効果は、Cr、Zrなどの化合物粒子の方が、Mnの化合物粒子よりも大きいと思われがちである。
【0018】
しかし、一方、Cr、Zrなどの化合物粒子には、核生成サイトを減少させる作用もあり、この作用が大きいと、結晶粒の形状は、球状の等軸状ではなく、圧延方向に伸長した伸長粒となる。そして、この伸長粒は、特に、350 ℃以上の高温の再結晶焼鈍時には、より粗大化しやすい。したがって、この結果が、Cr、Zrなどの化合物粒子とMnの化合物粒子の再結晶粒度の微細化 (粗大化防止) 効果の差につながっているものと推考される。
【0019】
このため、Cr、Zrなどの化合物粒子は、350 ℃未満の低温の再結晶焼鈍時には再結晶粒度の微細化効果を発揮するものの、350 ℃以上の高温の再結晶焼鈍時には再結晶粒度の微細化効果が弱くなる。この結果、最終焼鈍後のAl-Mg 系Al合金板の再結晶粒度を、通常の再結晶粒度20〜30μm のレベル以下の微細粒とはできるものの、本発明の主目的である5 μm 以下の超微細粒とすることができなくなる。
【0020】
また、Mnの化合物粒子が粗大化した場合には、特に、350 ℃以上の高温の再結晶焼鈍時における、Mnの化合物粒子自体の再結晶粒度の微細化効果が弱くなることも、本発明者らは知見した。そこで、本発明者らは、Mn化合物粒子の粗大化の、再結晶粒度の微細化効果発揮の臨界的な大きさとして、Al-Mg 系Al合金板の結晶粒内に分散析出するAl-Mg 系化合物の最大長さを500nm 以下とすべきことを更に知見して、本発明をなしたものである。
【0021】
【発明の実施の形態】
(Al-Mn 系化合物粒子)
本発明で言うAl-Mn 系化合物粒子とは、FeやSiが含まれない場合にはMnAl6 であり、FeやSiが含まれる場合には、(Fe,Mn)3SiAl12、(Fe,Mn)Al6等の化合物である。
【0022】
そして、本発明では、これらAl-Mn 系化合物粒子の最大長さを500nm 以下と規定する。Al-Mn 系化合物粒子の最大長さが500nm を越えて粗大化した場合、前記した、Al合金組織内における、Al-Mn 系化合物粒子の微細分散析出による、350 ℃以上の高温の再結晶焼鈍時の再結晶粒度の微細化効果が弱くなる。この結果、最終焼鈍後のAl-Mg 系Al合金板の再結晶粒度を、通常の再結晶粒度20〜30μm のレベル以下の微細粒とはできるものの、本発明の主目的である5 μm 以下の超微細粒とすることができなくなる。
【0023】
Al-Mn 系化合物粒子の最大長さは、Al-Mn 系化合物粒子の形状にもよるが、Al-Mn 系化合物粒子の形状の内、最も長い部分の長さである。例えば、Al-Mn 系化合物粒子が板状の場合には最大の辺の長さ、粒状の場合には最大の径の長さ等が該当する。
【0024】
これらAl-Mn 系化合物粒子の最大長さの測定と同定 (検証) は、Al合金組織の10000 倍以上の透過電子顕微鏡(TEM) による、観察により行う。なお、透過型電子顕微鏡による測定は、機械研磨で約0.1mm 厚みに薄肉化した測定用試料を、更に、電解研磨 (ジェットポリッシュ) で観察部位の厚さを局部的に0.1 〜0.3 μm(1000〜3000Å) の薄膜化した部位をTEM で観察して行う。そして、各視野で測定できるAl-Mn 系化合物粒子の最大長さを各々計測し、1 視野当たりの化合物粒子の最大長さを10視野で平均値化したものとする。
【0025】
また、Al合金板の再結晶粒度の測定は、光学顕微鏡および走査電子顕微鏡(SEM) を用い、切断法により行う。より具体的には、直線で切断される結晶粒の数が100 個以上となるように直線を描き、この直線の長さを切断された結晶粒の数で除して、再結晶粒度とする。
【0026】
(本発明Al合金の化学成分組成)
次に、本発明Al合金における、化学成分組成について説明する。
【0027】
(本発明Al合金の各元素量)
Mg:3.0〜10.0% 。
Mgは、Al合金板に構造材に必要な強度と成形性を固溶強化により付与するとともに、大圧下による冷間圧延時の回復を抑制し、最終焼鈍後の再結晶粒度を微細にするために必須の元素である。Mgの3.0%未満の含有では、固溶強化が十分ではなく、更に大圧下による冷間圧延時の回復を抑制できず、最終焼鈍後の再結晶粒度の微細化が困難となる。この結果、必要な強度や成形性が不足する。また、一方、10.0% を越えて含有されると、鋳造や熱間圧延などの板の製造自体が困難となり、大圧下による冷間圧延時のエッジクラックも増大するため、工業的な製造に適さなくなる。したがって、Mgの含有量は3.0 〜10.0% の範囲とする。
【0028】
Mn:0.1〜1.5%
Mnは、前記した通り、微細なAl-Mn 系化合物粒子の形成と、350 ℃以上の高温の再結晶焼鈍 (最終焼鈍後) 後の再結晶粒度の微細化、特に、再結晶粒度が5 μm 以下の超微細化のために必要な元素である。Mnの含有量が0.1%未満では、組織内に形成されるAl-Mn 系化合物粒子の量 (数) が不足し、350 ℃以上の高温の最終焼鈍後の再結晶粒度を5 μm 以下の超微細化させることができない。一方、Mnの含有量が1.5%を越えた場合には、結晶粒微細化効果が飽和し、また、化合物粒子により、Al合金板の伸びおよび成形性が却って低下する。したがって、Mnの含有量は0.2 〜1.5%の範囲とする。
【0029】
Fe:0.1〜2.0%、Cr:0.05 〜0.2%、Zr:0.05 〜0.2%。
Fe、Cr、Zrは、再結晶焼鈍後の再結晶粒度の微細化の効果がある点で同効元素である。
【0030】
Feは、Al-Fe 系の化合物粒子 (晶出物) を形成し、再結晶焼鈍 (最終焼鈍後) 時の核生成サイトとなって、再結晶粒度の微細化の効果を発揮する元素である。0.1%未満の含有ではこの効果が不足し、一方、2.0%を越えた場合には、却って、再結晶焼鈍後のAl合金板の成形性や伸びなどを低下させる。したがって、Feの含有量は0.1 〜2.0%の範囲とする。
【0031】
Cr、Zrは、前記Mnと同様に、Al-Cr 系、Al-Zr 系の化合物粒子を形成し、再結晶焼鈍 (最終焼鈍後) 後の再結晶粒度の微細化の効果がある同効元素である。前記した通り、これらの再結晶粒度の微細化元素は、350 ℃以上の高温の最終焼鈍後の再結晶粒度を5 μm 以下にする効果はないものの、350 ℃未満の低温の再結晶焼鈍時には、焼鈍後の再結晶粒度を5 μm 以下にする微細化効果を発揮する。したがって、選択的に含ませる場合には、Mnを必須とし、これに加えて、一種または2 種以上を組み合わせて用いる。
【0032】
各々の下限量未満では、結晶粒内に形成される各々の化合物粒子の数乃至量が不足し、再結晶焼鈍時の再結晶粒度を5 μm 以下にする微細化効果が無い。一方で、各々の上限量を越えた場合には、結晶粒微細化効果が飽和し、また、粗大な晶出物を生成し、却って、Al合金板の破壊靱性および疲労特性、あるいは伸びや成形性などを劣化させる。したがって、各々の含有量は、Cr:0.05 〜0.2%、Zr:0.05 〜0.2%の範囲とする。
【0033】
Ti:0.001 〜0.1%、B:1 〜300ppm。
Ti、B は鋳塊の結晶粒を微細化する効果がある。このため、特にTiは通常添加する元素である。Tiの0.001%未満、B の1ppm未満の含有では、この効果が得られず、一方、Tiを0.1%を越えて、またB を300ppmを越えて含有すると、粗大な晶出物を形成する。したがって、Ti、B を一種または二種含有する場合、Tiの含有量は0.001 〜0.1%の範囲、B の含有量は1 〜300ppmの範囲と、各々することが好ましい。
【0034】
(本発明Al合金板の製造方法)
Al合金板自体は常法により製造可能であるものの、最終焼鈍処理時および最終焼鈍処理後の、Al合金板の結晶粒内のAl-Mn 系化合物の最大長さを500nm 以下とするため、また、最終焼鈍後の再結晶粒度が5 μm 以下とするための好ましい工程条件について以下に説明する。
【0035】
Al-Mn 系化合物粒子の固溶と析出とを初期に支配する鋳造工程においては、固溶を促進して、析出を抑制することが好ましい。このためには、鋳造の際の冷却速度が早い方が好ましい。この点、固定式水冷鋳型を有する半連続鋳造法(DC鋳造法)よりは、回転式水冷鋳型などを有する双ロール法、ベルトキャスター法、3C法、ブロック法等の連鋳では、凝固時の冷却速度 (液相線温度から固相線温度まで) を2 ℃/sec〜10℃/secとすることが可能となる。
【0036】
これらAl合金鋳塊の熱間圧延前の均質化熱処理において、Al-Mn 系化合物粒子を微細にかつ多数析出させるためには、均質化熱処理温度を430 〜520 ℃程度とすることが好ましい。処理温度が520 ℃以上では、Al-Mn 系化合物粒子が粗大化する可能性が大きい。また、均質化熱処理温度が430 ℃未満では、固溶による均質化自体の効果が不足する。
【0037】
熱間圧延は常法により可能であるが、後述する冷間圧延の圧下率に対し、熱間圧延の加工度も影響を与える。後述する冷間圧延の加工度 (圧下率) を高くするために、最終板厚が同じ場合、熱間圧延終了時の板厚が厚い方が好ましい。また熱間圧延時に導入されるひずみ( 転位密度) が大きくすることが好ましく、このために、熱間圧延終了温度は低い方が好ましい。
【0038】
引き続く冷間圧延の圧下率は、最終焼鈍後の再結晶粒度が5 μm 以下とするために重要である。通常の冷間圧延Al-Mg 系Al合金板の再結晶粒度が、通常20〜30μm のレベルであるのは、Mg含有量が比較的低いことと、この冷間圧延の圧下率が大きくても90% 未満のレベルであることによる。このため、本発明では、90% 以上の圧下率で冷間圧延することが必要で、これ未満の圧下率では、最終焼鈍後の再結晶粒度を5 μm 以下とすることができない。90% 以上の圧下率で冷間圧延することにより、転位を高密度で導入するとともに局部変形領域を高密度に形成して、これらを再結晶の核生成サイトとして作用させ、最終焼鈍後の再結晶粒度を5 μm 以下とすることが可能となる。
【0039】
冷間圧延の際の中間焼鈍および冷間圧延後の最終焼鈍 (再結晶焼鈍) は、バッチ式の熱処理炉或いは連続式熱処理炉により、製品板に要求される機械的特性や成形性などの要求特性に応じた、温度と時間により行う。
【0040】
なお、高温焼鈍によっても再現性よく再結晶粒度の超微細化を行うために、高温の最終焼鈍の前に、Al-Mn 系化合物を再現性よく微細化しておくためには、単に化学成分や通常の基本的な製造工程だけではなく、鋳塊の鋳造における冷却速度や均質化熱処理条件を合わせて考慮して、Al-Mn 系化合物の大きさを制御することが重要である。言い換えると、他の条件が同じでも、鋳造における冷却速度や均質化熱処理条件が異なる場合には、Al-Mn 系化合物の大きさがかなり異なってくる。
【0041】
【実施例】
次に、本発明方法の実施例を説明する。表1 に示すNo.A〜J までの、化学成分組成を有するAl-Mg 系Al合金を用い、表2 に示す通り、種々製造条件を変えてAl合金板の供試材を製造した。
【0042】
因みに、表1 の内、A 〜C は本発明範囲内の組成で、Mn量を変えた発明例である。
また、D 〜G は本発明範囲内の組成で、Fe、Cr、Zrの一種または二種以上を添加した発明例で、D はMg量が上限の発明例、E はMg量が比較的少ない発明例である。
更に、H 〜J は本発明範囲外の組成で、H はMn等の微細化元素を含まない比較例、I はMnが下限量未満で、Fe、Cr、Zrの三種を添加した比較例、J はMg量が下限量未満の比較例である。
【0043】
Al合金板の具体的な製造方法は、Al-Mg 系Al合金鋳塊をDC鋳造法 (冷却速度 5℃/ 秒) により50mm厚みの鋳塊に溶製した後、表2 に示す各温度で、4 時間の均質化熱処理 (昇温速度は共通して50℃/ 秒) を施した。そして、この熱処理温度から熱間圧延を開始し、300 ℃で圧延を終了し、厚さ10mmまで熱間圧延した。更に、これらの熱延板を、厚さ0.4 〜1.5mm まで、最大96% の大圧下率から85% の圧下率まで、表2 に示す圧下率で冷間圧延した。そして、この冷間圧延板をソルトバスを用いて、表2 に示す温度で20秒間 (昇温速度は共通して100 ℃/ 秒) 最終焼鈍 (再結晶焼鈍) を施した。
【0044】
因みに、表2 の内、No.1〜3 は、表1 のA の本発明範囲内の組成のAl合金板を用い、最終焼鈍を350 〜500 ℃まで変えた発明例である。
No.4は、A の本発明範囲内の組成のAl合金板を用い、冷間圧延圧下率が本発明下限の90% とした発明例である。
No.5は、A の本発明範囲内の組成のAl合金板を用い、均質化熱処理の温度が470 ℃と比較的低い発明例である。
No.6〜11は、表1 のB 〜G までの本発明範囲内の組成のAl合金板を用い、製造条件を全く同じとした発明例である。
【0045】
更に、表2 の内、No.12 〜14は、表1 のH 〜J までの本発明範囲外の組成のAl合金板を用い、製造条件を発明例No.1と全く同じとした比較例である。
また、No.15 は、表1 のA の本発明範囲内の組成のAl合金板を用い、冷間圧延圧下率が本発明下限未満の85% とした比較例である。
そして、No.16 は、均質化熱処理の温度を540 ℃と比較的高くした比較例である。
【0046】
(Al-Mn 系化合物粒子の測定)
各例のAl合金板の再結晶粒内のAl-Mn 系化合物粒子の同定と最大長さ、さらに再結晶粒の大きさ (再結晶粒度) を各々前記した測定方法により測定した。これらの結果を表2 に示す。
【0047】
(Al合金板の特性評価)
また、引張試験(JIS Z 2241 法) にて引張試験を行い、引張強さ (σB ) 、耐力 (σ0.2)、伸び(%) を測定した。これらの結果を表2 に示す。
【0048】
また、前記各供試板のプレス成形性を評価するために、供試板よりブランク材を採取して、 LDHO 測定用の金型 (直径50.8mmφの球頭パンチ) を用いて、簡易的な球頭張出試験を行い、その際に割れを生じずに成形できた LDHO (最大張出高さ) を求めた。これらの結果も表2 に示す。
【0049】
表2 から明らかな通り、発明例No.1〜11は、最終焼鈍が350 ℃以上の500 ℃の高温となっても、Al合金板の再結晶粒内のAl-Mn 系化合物粒子の最大長さが500nm 以下であり、再結晶粒度が5 μm 以下の超微細粒となっている。この結果、表2 に示す通り、優れた引張強さ (σB ) 、耐力 (σ0.2)、伸び(%) とともに、高い成形限界高さを示している。また、発明例No.11 は、最終焼鈍が320 ℃の低温の際にも、再結晶粒度が勿論5 μm 以下の超微細粒となることを示している。したがって、この結果から、本発明Al合金板は、最終焼鈍温度を、低温から高温まで、要求特性に応じて適宜選択できる利点を有することも示している。
【0050】
また、発明例No.3の結果は、前記特願平11-268599 号の実施例 (Mnを含むAl-Mg 系Al合金板の最終焼鈍温度が高い場合に再結晶粒度が5 μm を越えて粗大化) の傾向なり方向を裏付けている。
【0051】
一方、表2 の内、表1 のH 〜J までの本発明範囲外の組成のAl合金板を用い、製造条件を発明例No.1と全く同じとした比較例No.12 、13は、Al-Mn 系化合物粒子自体が無いか、または量が少なく、比較例No.14 はMg量が少ないために、いずれも再結晶の核生成サイトが不足し、350 ℃以上の高温の再結晶焼鈍時に再結晶粒度が5 μm 以下の超微細粒とすることができない。
また、表1 のA の本発明範囲内の組成のAl合金板を用い、冷間圧延圧下率が本発明下限未満の85% とした比較例No.15 は、再結晶の核生成サイトが不足し、350 ℃以上の高温の再結晶焼鈍時に再結晶粒度が5 μm 以下の超微細粒とすることができない。
更に、表1 のA の本発明範囲内の組成のAl合金板を用い、均質化熱処理温度を540 ℃の高温とした比較例No.16 は、Al-Mn 系化合物粒子の最大長さが500nm を超え、350 ℃以上の高温の再結晶焼鈍時に再結晶粒度が5 μm 以下の超微細粒とすることができない。
そして、この結果、これら各比較例はいずれも表2 に示す通り、引張強さ (σB ) 、耐力 (σ0.2)、伸び(%) 、成形限界高さが、発明例に比して著しく劣っている。
【0052】
したがって、これらの結果から、本発明の要件の臨界的な意義や好ましい製造条件の意義が分かる。また、再結晶焼鈍温度、そして合金組成や製造条件によって、Al-Mn 系化合物粒子の最大長さや再結晶粒度が大きく異なり、本発明のAl-Mn 系化合物粒子の最大長さの規定によって始めて、350 ℃以上の高温の再結晶焼鈍時の再結晶粒度5 μm 以下が保証されることが分かる。
【0053】
【表1】
【0054】
【表2】
【0055】
【発明の効果】
本発明によれば、高温の再結晶焼鈍を行っても、焼鈍後の再結晶粒度を5 μm 以下の超微細粒とすることが可能なAl-Mg 系Al合金板を提供することができる。この結果、輸送機用のAl合金材の用途を大きく拡大できる点で工業的な価値が大きい。
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-strength, high-formability aluminum alloy plate (hereinafter, aluminum is simply referred to as Al) excellent in recrystallization grain refinement during high-temperature annealing.
[0002]
[Prior art]
Mainly AA to JIS 5052 as structural members and structural parts such as railway vehicles, aircraft, ships, automobiles, motorcycles, bicycles, etc., chemical plants such as pressure vessels and tanks, and buildings and structures. , 5056, 5082, 5182, 5083, 5086, etc., Al—Mg based to 5000 based Al alloy plates containing Mg of 3.5% (mass%, the same shall apply hereinafter) or more are used. These Al-Mg-based Al alloy plates having a high Mg content have excellent strength and formability and good weldability, and are therefore widely used as welded structural members.
[0003]
As is well known, this Al-Mg-based Al alloy sheet is obtained by homogenizing heat treatment of an ingot by a conventional method, and after making it a predetermined sheet thickness by hot rolling and cold rolling, and then performing recrystallization annealing to obtain an Al alloy. It is made a board. And the recrystallized grain size of this Al-Mg system Al alloy plate is a level of 20-30 micrometers normally.
[0004]
On the other hand, in recent years, in order to further improve the strength and formability of this Al—Mg-based Al alloy plate, it has been studied to make the recrystallized grain size finer. For example, in Japanese Patent Application No. 11-268599, up to 7.0% Mg is contained, and Fe: 0.1-2.0%, Cr: 0.05-0.5%, Zr: 0.05-0.2%, one or more It has been proposed that an Al-Mg-based Al alloy containing Ni be added to a large pressure of 90% or more in cold rolling to make the recrystallized grain size after recrystallization annealing into 5 μm or less.
[0005]
With this technology, the Mg content is extremely increased, and a large pressure is applied in cold rolling to increase compound particles containing dislocations and Fe that become nucleation sites for recrystallization, and Mn, Cr, Zr These are intended to suppress the coarse growth of recrystallized grains due to the movement of grain boundaries.
[0006]
[Problems to be solved by the invention]
This recrystallized grain refinement technology makes it possible to actually manufacture Al-Mg-based Al alloy sheets with ultrafine grains having a recrystallized grain size of 5 μm or less after recrystallization annealing. However, with this recrystallized grain refinement technology, the recrystallization annealing temperature must be as low as 350 ° C. or less in order to reduce the recrystallized grain size to 5 μm or less. In other words, when the recrystallization annealing temperature is set to a temperature exceeding 350 ° C., the recrystallized grains become coarse and the grain size cannot be reduced to 5 μm or less.
[0007]
In this recrystallized grain refinement technique, the Mg content is extremely increased and a large reduction is applied in cold rolling, so that the work hardening amount of the Al alloy sheet is extremely large. For this reason, if the temperature during recrystallization annealing is constrained to the low temperature side, annealing may be insufficient and formability such as elongation and drawing height required for the various applications may not be satisfied. There is.
[0008]
In this respect, the above-mentioned Japanese Patent Application No. 11-268599 also clearly states that the final annealing temperature needs to be a low temperature of 350 ° C. or less, and in the examples, Mn: 0.2%, Fe: For an Al-Mg-based Al alloy sheet containing 1.26% and Cr: 0.15%, when the final annealing temperature is 420 ° C, the recrystallized grain size is 5 μm compared to the invention example with an annealing temperature of less than 350 ° C. It is described that the material becomes coarser and the properties such as formability of the Al alloy plate are deteriorated.
[0009]
Therefore, in this recrystallized grain refinement technique, it is necessary to set the annealing temperature to a low temperature of less than 350 ° C. in order to make the recrystallized grain size after recrystallization annealing 5 μm or less. For this reason, depending on the application, there may be cases where the required formability cannot be satisfied, for example, the strength is too high or the SS mark specific to Al-Mg Al alloy sheets is generated, which may limit the applications of Al alloy sheets. There is.
[0010]
The present invention has been made paying attention to such circumstances, and its purpose is to make the recrystallized grain size after annealing into ultrafine grains of 5 μm or less even when high-temperature recrystallization annealing is performed. It is intended to provide a possible Al-Mg-based Al alloy sheet.
[0011]
[Means for Solving the Problems]
In order to achieve this object, the gist of the Al-Mg-based Al alloy sheet of the present invention includes Mg: 3.0 to 10.0% (mass%, the same shall apply hereinafter), Mn: 0.1 to 1.5%, and the balance Al and unavoidable impurities. Al-Mg Al alloy sheet with a recrystallization grain size of 5 μm or less after final annealing, with a reduction of 90% or more in cold rolling, and Al-Mn dispersed and precipitated in the structure The maximum length of the compound is to be 500 nm or less.
[0012]
Further, as another embodiment of the Al alloy plate of the present invention to which a selective additive element is added, the Al alloy plate further comprises Fe: 0.1 to 2.0%, Cr: 0.05 to 0.2%, Zr: 0.05 to 0.2%. Or containing two or more (corresponding to claim 2) and / or containing one or two of Ti: 0.001 to 0.1% and B: 1 to 300 ppm (corresponding to claim 3).
[0013]
A preferred application of the Al alloy sheet of the present invention is that it is used for final annealing at a high temperature exceeding 350 ° C. (corresponding to claim 4).
[0014]
The present invention is premised on the technical idea of Japanese Patent Application No. 11-268599. In other words, the Mg content is increased, and a large reduction is applied in cold rolling to increase the dislocations that become nucleation sites of recrystallization, and in addition, Fe compound particles (crystallized products) that become nucleation sites. In addition, compound particles (precipitates) such as Mn, Cr, and Zr suppress the coarse growth of recrystallized grains due to grain boundary movement, and the recrystallized grain size after final annealing is 5 μm or less. Is the same as Japanese Patent Application No. 11-268599. Therefore, the present invention is premised on the essential addition of Mn described later and that the Al alloy sheet is cold-rolled at a large reduction rate of 90% or more.
[0015]
However, the present inventors firstly added to the compound particles or dispersed particles (precipitates) such as Mn, Cr, Zr, etc., which should suppress coarse growth of recrystallized grains due to grain boundary migration, at a high temperature of 350 ° C. or higher. It was found that there was a difference in the recrystallization grain size refinement (preventing coarsening) effect when recrystallization annealing was not performed during recrystallization annealing at a temperature lower than 350 ° C.
[0016]
That is, compound particles such as Mn, Cr, and Zr are generated during the homogenization heat treatment of the Al—Mg-based Al alloy ingot, as is well known. However, depending on the content, casting conditions, and conditions during the homogenization heat treatment, the size and shape of the compound particles are particularly different.This is the refining of the recrystallized grain size during recrystallization annealing at a high temperature of 350 ° C or higher (coarse Prevention) leads to a difference in effect.
[0017]
In particular, compound particles such as Cr and Zr are usually smaller than the size of Mn compound particles. Therefore, usually, the effect of suppressing the growth of crystal grains tends to be considered to be larger for compound particles such as Cr and Zr than for Mn compound particles.
[0018]
However, compound particles such as Cr and Zr also have the effect of reducing nucleation sites. When this effect is large, the shape of the crystal grains is not a spherical equiaxed shape, but stretched in the rolling direction. It becomes a grain. The elongated grains are more likely to become coarser, particularly during recrystallization annealing at a high temperature of 350 ° C. or higher. Therefore, it is inferred that this result leads to a difference in the effect of refinement of recrystallized particle size (preventing coarsening) between compound particles such as Cr and Zr and Mn compound particles.
[0019]
For this reason, compound particles such as Cr and Zr exhibit a recrystallization grain refinement effect when recrystallization annealing is performed at a low temperature of less than 350 ° C, but recrystallization grain refinement occurs when recrystallization annealing is performed at a high temperature of 350 ° C or more. The effect is weakened. As a result, although the recrystallized grain size of the Al-Mg-based Al alloy sheet after the final annealing can be made a fine grain below the level of the usual recrystallized grain size of 20-30 μm, it is less than 5 μm which is the main object of the present invention. It becomes impossible to make ultrafine particles.
[0020]
In addition, when the Mn compound particles are coarsened, the effect of refining the recrystallized particle size of the Mn compound particles themselves, especially during recrystallization annealing at a high temperature of 350 ° C. or higher, becomes weaker. Found out. Therefore, the inventors of the present invention determined that Al-Mg dispersed and precipitated in the crystal grains of an Al-Mg-based Al alloy sheet as a critical size for the effect of refinement of the recrystallization grain size in the coarsening of Mn compound particles. The present invention has been made by further finding out that the maximum length of the system compound should be 500 nm or less.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
(Al-Mn compound particles)
The Al-Mn-based compound particles referred to in the present invention are MnAl 6 when Fe and Si are not included, and (Fe, Mn) 3 SiAl 12 and (Fe, when Fe and Si are included). Mn) Al 6 and other compounds.
[0022]
In the present invention, the maximum length of these Al—Mn compound particles is defined as 500 nm or less. When the maximum length of the Al-Mn compound particles exceeds 500 nm, the recrystallization annealing is performed at a high temperature of 350 ° C or higher due to the finely dispersed precipitation of the Al-Mn compound particles in the Al alloy structure. The effect of refining the recrystallized grain size is weakened. As a result, although the recrystallized grain size of the Al-Mg-based Al alloy sheet after the final annealing can be made a fine grain below the level of the usual recrystallized grain size of 20 to 30 μm, It becomes impossible to make ultrafine particles.
[0023]
The maximum length of the Al-Mn compound particles depends on the shape of the Al-Mn compound particles, but is the length of the longest portion of the shape of the Al-Mn compound particles. For example, the maximum side length corresponds when the Al-Mn compound particles are plate-like, and the maximum diameter length corresponds when the particles are granular.
[0024]
The measurement and identification (verification) of the maximum length of these Al-Mn compound particles is performed by observation with a transmission electron microscope (TEM) 10,000 times or more of the Al alloy structure. Measurements using a transmission electron microscope were carried out using a measurement sample that had been thinned to about 0.1 mm by mechanical polishing, and the thickness of the observation site was locally 0.1 to 0.3 μm (1000 μm) by electrolytic polishing (jet polishing). This is done by observing the thinned part (~ 3000mm) with TEM. Then, the maximum length of the Al—Mn compound particles that can be measured in each visual field is measured, and the maximum length of the compound particles per visual field is averaged in 10 visual fields.
[0025]
The recrystallized grain size of the Al alloy plate is measured by a cutting method using an optical microscope and a scanning electron microscope (SEM). More specifically, a straight line is drawn so that the number of crystal grains cut by a straight line is 100 or more, and the length of the straight line is divided by the number of cut crystal grains to obtain a recrystallized grain size. .
[0026]
(Chemical composition of Al alloy of the present invention)
Next, the chemical component composition in the Al alloy of the present invention will be described.
[0027]
(Each element amount of the Al alloy of the present invention)
Mg: 3.0 to 10.0%.
Mg adds strength and formability necessary for structural materials to Al alloy sheets by solid solution strengthening, suppresses recovery during cold rolling due to large pressure, and makes the recrystallized grain size after final annealing fine. It is an essential element. If the Mg content is less than 3.0%, solid solution strengthening is not sufficient, and recovery during cold rolling due to large pressure cannot be suppressed, and it is difficult to refine the recrystallized grain size after final annealing. As a result, the required strength and formability are insufficient. On the other hand, if the content exceeds 10.0%, it is difficult to produce a plate such as casting or hot rolling, and edge cracks during cold rolling due to large pressure increase, which is suitable for industrial production. Disappear. Therefore, the Mg content is in the range of 3.0 to 10.0%.
[0028]
Mn: 0.1-1.5%
As described above, Mn forms fine Al-Mn compound particles and refines the recrystallized grain size after recrystallization annealing at a high temperature of 350 ° C or higher (after final annealing). It is an element necessary for the following ultra-miniaturization. If the Mn content is less than 0.1%, the amount (number) of Al-Mn compound particles formed in the structure is insufficient, and the recrystallized grain size after final annealing at a high temperature of 350 ° C or higher exceeds 5 μm or less. It cannot be made finer. On the other hand, when the Mn content exceeds 1.5%, the effect of crystal grain refinement is saturated, and the elongation and formability of the Al alloy sheet are reduced by the compound particles. Therefore, the Mn content is in the range of 0.2 to 1.5%.
[0029]
Fe: 0.1-2.0%, Cr: 0.05-0.2%, Zr: 0.05-0.2%.
Fe, Cr, and Zr are synergistic elements in that they have the effect of reducing the recrystallization grain size after recrystallization annealing.
[0030]
Fe is an element that forms Al-Fe-based compound particles (crystallized product) and serves as a nucleation site during recrystallization annealing (after final annealing), and exerts an effect of refining the recrystallized grain size. . If the content is less than 0.1%, this effect is insufficient. On the other hand, if it exceeds 2.0%, the formability and elongation of the Al alloy sheet after recrystallization annealing are lowered. Therefore, the Fe content is in the range of 0.1 to 2.0%.
[0031]
Cr and Zr, like Mn, form Al-Cr and Al-Zr-based compound particles, and have the effect of refining the recrystallized grain size after recrystallization annealing (after final annealing) It is. As described above, these recrystallized grain refining elements have no effect of reducing the recrystallized grain size after final annealing at a high temperature of 350 ° C. or higher to 5 μm or less, but during recrystallization annealing at a low temperature of less than 350 ° C., It has the effect of miniaturizing the recrystallized grain size after annealing to 5 μm or less. Therefore, when it is selectively included, Mn is essential, and in addition to this, one or a combination of two or more is used.
[0032]
If the amount is less than the lower limit of each, the number or amount of each compound particle formed in the crystal grains is insufficient, and there is no refining effect for reducing the recrystallized particle size during recrystallization annealing to 5 μm or less. On the other hand, when each upper limit is exceeded, the effect of crystal grain refinement is saturated, and coarse crystallized products are formed. On the other hand, fracture toughness and fatigue characteristics of Al alloy sheets, or elongation and forming Degradation etc. Accordingly, the respective contents are in the range of Cr: 0.05 to 0.2% and Zr: 0.05 to 0.2%.
[0033]
Ti: 0.001 to 0.1%, B: 1 to 300 ppm.
Ti and B have the effect of refining the ingot crystal grains. For this reason, Ti is an element that is usually added. This effect cannot be obtained when the Ti content is less than 0.001% and the B content is less than 1 ppm. On the other hand, when the Ti content exceeds 0.1% and the B content exceeds 300 ppm, coarse crystals are formed. Therefore, when one or two of Ti and B are contained, the Ti content is preferably in the range of 0.001 to 0.1%, and the B content is preferably in the range of 1 to 300 ppm.
[0034]
(Production method of the present invention Al alloy plate)
Although the Al alloy plate itself can be manufactured by a conventional method, the maximum length of the Al-Mn compound in the crystal grains of the Al alloy plate during the final annealing process and after the final annealing process is set to 500 nm or less. The preferable process conditions for setting the recrystallization grain size after final annealing to 5 μm or less will be described below.
[0035]
In the casting process in which the solid solution and precipitation of Al-Mn compound particles are initially controlled, it is preferable to promote solid solution and suppress precipitation. For this purpose, it is preferable that the cooling rate during casting is faster. In this regard, in continuous casting such as a twin-roll method, a belt caster method, a 3C method, and a block method having a rotary water-cooled mold, the semi-continuous casting method having a fixed water-cooled mold (DC casting method) The cooling rate (from the liquidus temperature to the solidus temperature) can be 2 ° C / sec to 10 ° C / sec.
[0036]
In the homogenization heat treatment before hot rolling of these Al alloy ingots, the homogenization heat treatment temperature is preferably about 430 to 520 ° C. in order to precipitate a large number of Al—Mn compound particles. When the treatment temperature is 520 ° C. or higher, there is a high possibility that the Al—Mn compound particles become coarse. If the homogenization heat treatment temperature is less than 430 ° C, the effect of homogenization by solid solution is insufficient.
[0037]
Although hot rolling is possible by a conventional method, the degree of work of hot rolling also affects the rolling reduction of cold rolling described later. In order to increase the workability (rolling rate) of cold rolling, which will be described later, when the final plate thickness is the same, it is preferable that the plate thickness at the end of hot rolling is thick. In addition, it is preferable to increase the strain (dislocation density) introduced during hot rolling. For this reason, it is preferable that the hot rolling end temperature is low.
[0038]
The subsequent cold rolling reduction ratio is important for the recrystallized grain size after final annealing to be 5 μm or less. The recrystallized grain size of normal cold-rolled Al-Mg-based Al alloy sheets is usually at a level of 20-30 μm, even if the Mg content is relatively low and the cold rolling reduction ratio is large. This is because the level is less than 90%. For this reason, in the present invention, it is necessary to cold-roll at a reduction ratio of 90% or more. With a reduction ratio less than this, the recrystallized grain size after the final annealing cannot be reduced to 5 μm or less. By cold rolling at a rolling reduction of 90% or more, dislocations are introduced at a high density, and local deformation regions are formed at a high density, which act as nucleation sites for recrystallization, and are regenerated after final annealing. The crystal grain size can be reduced to 5 μm or less.
[0039]
The intermediate annealing during cold rolling and the final annealing (recrystallization annealing) after cold rolling are performed in batch-type heat treatment furnace or continuous heat treatment furnace. Perform by temperature and time according to the characteristics.
[0040]
In order to achieve ultra-fine recrystallized grain size with high reproducibility even by high-temperature annealing, in order to refine Al-Mn compounds with high reproducibility before high-temperature final annealing, the chemical components and It is important to control the size of the Al-Mn compound in consideration of not only the normal basic manufacturing process but also the cooling rate and homogenization heat treatment conditions in ingot casting. In other words, even if the other conditions are the same, the size of the Al-Mn compound varies considerably when the cooling rate and homogenization heat treatment conditions in casting are different.
[0041]
【Example】
Next, examples of the method of the present invention will be described. Using Al—Mg-based Al alloys having chemical composition from Nos. A to J shown in Table 1, as shown in Table 2, various production conditions were changed to produce specimens for Al alloy sheets.
[0042]
Incidentally, in Table 1, A to C are invention examples in which the amount of Mn is changed with the composition within the range of the present invention.
D to G are compositions within the scope of the present invention, and one or more of Fe, Cr, and Zr are added. D is an invention example with an upper limit of Mg content, and E is a relatively small amount of Mg. It is an example of an invention.
Furthermore, H ~ J is a composition outside the scope of the present invention, H is a comparative example not containing a refining element such as Mn, I is a comparative example in which Mn is less than the lower limit amount, and three types of Fe, Cr, Zr are added, J is a comparative example in which the Mg amount is less than the lower limit amount.
[0043]
A specific method for producing an Al alloy plate is as follows: an Al-Mg-based Al alloy ingot is melted into a 50 mm-thick ingot by the DC casting method (cooling rate 5 ° C / second), and then at each temperature shown in Table 2. 4 hours of homogenization heat treatment (heating rate is 50 ℃ / second in common). Then, hot rolling was started from this heat treatment temperature, the rolling was finished at 300 ° C., and hot rolled to a thickness of 10 mm. Further, these hot-rolled sheets were cold-rolled at a reduction rate shown in Table 2 from a maximum reduction rate of 96% to a reduction rate of 85% up to a thickness of 0.4 to 1.5 mm. Then, this cold-rolled sheet was subjected to final annealing (recrystallization annealing) at a temperature shown in Table 2 for 20 seconds (a common heating rate was 100 ° C./second) using a salt bath.
[0044]
Incidentally, Nos. 1 to 3 in Table 2 are invention examples in which an Al alloy plate having a composition within the range of the present invention of A in Table 1 was used and the final annealing was changed to 350 to 500 ° C.
No. 4 is an example of the invention in which an Al alloy plate having a composition within the scope of the present invention of A is used and the cold rolling reduction is 90% of the lower limit of the present invention.
No. 5 is an invention example in which an Al alloy plate having a composition within the scope of the present invention of A is used and the temperature of the homogenization heat treatment is relatively low at 470 ° C.
Nos. 6 to 11 are invention examples using Al alloy plates having compositions within the scope of the present invention from B to G in Table 1 and having exactly the same manufacturing conditions.
[0045]
Further, in Table 2, Nos. 12 to 14 are comparative examples in which Al alloy plates having compositions outside the scope of the present invention up to H to J in Table 1 were used, and the production conditions were exactly the same as those of Invention Example No. It is.
No. 15 is a comparative example in which an Al alloy plate having a composition within the scope of the present invention of A in Table 1 was used and the cold rolling reduction was 85% below the lower limit of the present invention.
No. 16 is a comparative example in which the temperature of the homogenization heat treatment is relatively high at 540 ° C.
[0046]
(Measurement of Al-Mn compound particles)
The identification and maximum length of the Al—Mn-based compound particles in the recrystallized grains of the Al alloy plate of each example and the size of the recrystallized grains (recrystallized grain size) were measured by the measurement methods described above. These results are shown in Table 2.
[0047]
(Characteristic evaluation of Al alloy sheet)
Further, a tensile test was performed by a tensile test (JIS Z 2241 method), and tensile strength (σ B ), proof stress (σ 0.2 ), and elongation (%) were measured. These results are shown in Table 2.
[0048]
In order to evaluate the press formability of each test plate, a blank was sampled from the test plates, with a die for LDH O measured (spherical head punch diameter 50.8Mmfai), short The ball head overhang test was conducted, and LDH 2 O (maximum overhang height) that could be molded without cracking was determined. These results are also shown in Table 2.
[0049]
As apparent from Table 2, Invention Examples Nos. 1 to 11 have the maximum length of Al-Mn compound particles in the recrystallized grains of the Al alloy plate even when the final annealing is a high temperature of 500 ° C., which is 350 ° C. or higher. The size is 500 nm or less, and the recrystallized grain size is 5 μm or less. As a result, as shown in Table 2, high tensile limit (σ B ), proof stress (σ 0.2 ), and elongation (%), as well as a high forming limit height are shown. Invention Example No. 11 shows that even when the final annealing is at a low temperature of 320 ° C., the recrystallized grain size of course becomes ultrafine grains of 5 μm or less. Therefore, this result also shows that the Al alloy sheet of the present invention has an advantage that the final annealing temperature can be appropriately selected from a low temperature to a high temperature according to required characteristics.
[0050]
In addition, the result of Invention Example No. 3 is the result of the example of the aforementioned Japanese Patent Application No. 11-268599 (when the final annealing temperature of the Al-Mg-based Al alloy sheet containing Mn is high, the recrystallized grain size exceeds 5 μm). The tendency of the coarsening) is supported.
[0051]
On the other hand, in Table 2, Comparative Examples No. 12 and 13 using Al alloy plates having compositions outside the scope of the present invention from H to J in Table 1 and having the same manufacturing conditions as Invention Example No. 1, There is no Al-Mn compound particles per se, or the amount is small, and Comparative Example No. 14 has a small amount of Mg, so there are not enough nucleation sites for recrystallization, and recrystallization annealing at a high temperature of 350 ° C or higher. Sometimes, the recrystallized grain size cannot be reduced to 5 μm or less.
Further, Comparative Example No. 15 using an Al alloy sheet having a composition within the scope of the present invention of A in Table 1 and having a cold rolling reduction of 85% below the lower limit of the present invention has insufficient nucleation sites for recrystallization. However, when recrystallization annealing is performed at a high temperature of 350 ° C. or higher, the recrystallized grain size cannot be reduced to 5 μm or less.
Further, Comparative Example No. 16 using an Al alloy plate having a composition within the scope of the present invention of A in Table 1 and having a homogenization heat treatment temperature of 540 ° C. has a maximum length of Al-Mn compound particles of 500 nm. When the recrystallization annealing is performed at a high temperature of 350 ° C. or higher, the recrystallized grain size cannot be reduced to 5 μm or less.
As a result, as shown in Table 2, in each of these comparative examples, the tensile strength (σ B ), proof stress (σ 0.2 ), elongation (%), and forming limit height are remarkably higher than those of the inventive examples. Inferior.
[0052]
Therefore, from these results, the critical significance of the requirements of the present invention and the significance of preferred production conditions can be understood. In addition, the maximum length of Al-Mn compound particles and the recrystallized particle size vary greatly depending on the recrystallization annealing temperature, alloy composition and production conditions, and starting with the provision of the maximum length of Al-Mn compound particles of the present invention, It can be seen that a recrystallization grain size of 5 μm or less during recrystallization annealing at a high temperature of 350 ° C. or higher is guaranteed.
[0053]
[Table 1]
[0054]
[Table 2]
[0055]
【The invention's effect】
According to the present invention, it is possible to provide an Al—Mg-based Al alloy sheet capable of making the recrystallized grain size after annealing into ultrafine grains of 5 μm or less even when high-temperature recrystallization annealing is performed. As a result, the industrial value is great in that the application of the Al alloy material for transport aircraft can be greatly expanded.

Claims (4)

  1. Mg:3.0〜10.0% (質量% 、以下同じ) 、Mn:0.1〜1.5%を含み残部Alおよび不可避的不純物からなり、冷間圧延において90% 以上の圧下が加えられるとともに、最終焼鈍後の再結晶粒度が5 μm 以下である、Al-Mg 系アルミニウム合金板であって、組織内に分散析出するAl-Mn 系化合物の最大長さが500nm 以下であることを特徴とする高温焼鈍時の再結晶粒微細化に優れた高強度高成形性アルミニウム合金板。Mg: 3.0 to 10.0% (mass%, the same shall apply hereinafter), Mn: 0.1 to 1.5% and the balance Al and unavoidable impurities.In cold rolling, a reduction of 90% or more is applied, and An Al-Mg-based aluminum alloy plate with a grain size of 5 μm or less, wherein the maximum length of the Al-Mn-based compound dispersed and precipitated in the structure is 500 nm or less. High-strength, high-formability aluminum alloy sheet with excellent grain refinement.
  2. 前記アルミニウム合金板が、更に、Fe:0.1〜2.0%、Cr:0.05 〜0.2%、Zr:0.05 〜0.2%の一種または二種以上を含む請求項1に記載の高温焼鈍時の再結晶粒微細化に優れた高強度高成形性アルミニウム合金板。The recrystallized grain fineness during high-temperature annealing according to claim 1, wherein the aluminum alloy plate further contains one or more of Fe: 0.1 to 2.0%, Cr: 0.05 to 0.2%, and Zr: 0.05 to 0.2%. High strength, high formability aluminum alloy sheet with excellent resistance
  3. 前記アルミニウム合金板が、更に、Ti:0.001〜0.1%、B:1 〜300ppmの一種または二種を含む請求項1または2に記載の高温焼鈍時の再結晶粒微細化に優れた高強度高成形性アルミニウム合金板。3. The high strength and high strength excellent in recrystallization grain refinement during high temperature annealing according to claim 1 or 2, wherein the aluminum alloy plate further contains one or two of Ti: 0.001 to 0.1% and B: 1 to 300 ppm. Formable aluminum alloy plate.
  4. 前記焼鈍温度が350 ℃を越える請求項1乃至3のいずれか1項に記載の高温焼鈍時の再結晶粒微細化に優れた高強度高成形性アルミニウム合金板。The high-strength, high-formability aluminum alloy plate excellent in recrystallization grain refinement during high-temperature annealing according to any one of claims 1 to 3, wherein the annealing temperature exceeds 350 ° C.
JP27429399A 1999-09-28 1999-09-28 High-strength, high-formability aluminum alloy sheet with excellent recrystallization grain refinement during high-temperature annealing Expired - Fee Related JP4164206B2 (en)

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