JP3871473B2

JP3871473B2 - Method for producing aluminum alloy plate for can body

Info

Publication number: JP3871473B2
Application number: JP21064499A
Authority: JP
Inventors: 旭日比野; 俊雄小松原
Original assignee: Furukawa Sky Aluminum Corp
Current assignee: Furukawa Sky Aluminum Corp
Priority date: 1999-07-26
Filing date: 1999-07-26
Publication date: 2007-01-24
Anticipated expiration: 2019-07-26
Also published as: JP2001040461A

Description

【０００１】
【発明の属する技術分野】
この発明はＤＩ加工（絞り−しごき加工）による２ピースアルミニウム缶用の缶胴、すなわちＤＩ缶胴に用いられるＡｌ−Ｍｇ−Ｍｎ系アルミニウム合金板の製造方法に関し、特に深絞り耳が低くかつ塗装焼付後の強度が高く、しかもＤＩ加工時の成形性および塗装焼付後の成形性に優れたＤＩ缶胴用アルミニウム合金板の製造方法に関するものである。
【０００２】
【従来の技術】
一般に２ピースアルミニウム缶の製造工程としては、缶胴素材に対して深絞り加工およびしごき加工によるＤＩ成形を施して缶胴形状とした後、所定のサイズにトリミングを施して脱脂・洗浄処理を行ない、さらに塗装および印刷を行なって焼付け（ベーキング）を行ない、その後、缶胴縁部に対してネッキング加工、フランジング加工を行ない、その後、別に成形した缶蓋（缶エンド）と合せてシーミング加工を行なって缶とするのが通常である。
【０００３】
このようにして製造されるＤＩ缶の素材（缶胴材）としては、従来からＡｌ−Ｍｇ−Ｍｎ系合金であるＪＩＳ３００４合金の硬質板が広く用いられている。この３００４合金は、しごき加工性に優れていて、強度を高めるために高圧延率で冷間圧延を施した場合でも比較的良好な成形性を示すところから、ＤＩ缶胴材として好適であるとされている。
【０００４】
このようなＤＩ缶胴用の３００４合金硬質板の製造方法としては、ＤＣ鋳造法などによって鋳造後、鋳塊に対し均質化処理を施し、さらに熱間圧延および冷間圧延を施して所定の板厚とし、かつその過程における冷間圧延前あるいは冷間圧延中途において中間焼鈍を施す方法が一般的である。
【０００５】
ところでＤＩ缶胴については、主として材料コスト低減、軽量化の目的から、より薄肉化を図ることが強く望まれている。そしてこのように薄肉化を図るためには、薄肉化に伴なって生じる缶の座屈強度低下の問題を回避するため、材料の高強度化を図ることが不可欠である。
【０００６】
またＤＩ缶胴用材料については、上述のような薄肉化を図るための高強度化の要請ばかりではなく、ＤＩ成形時における耳率が低いことが強く望まれる。すなわち、ＤＩ成形時の耳率が低いことは、ＤＩ成形時の歩留りの向上と、缶胴の耳切れに起因する缶胴破断の防止の点から必要とされている。さらに、ＤＩ缶製造時におけるフランジ成形性（口拡げ性）、しごき性（缶切れ性）も重要であり、これらの耳率、フランジ成形性、しごき性、および強度を缶胴材に要求される主要４要素と称することができ、これらの４要素をバランス良く向上させることが強く望まれている。特に耳率は、これらの４要素のうちでもその制御が難しく、したがってこれらの４要素のバランスの改善には、耳率の適切な制御が極めて重要な課題となっている。
【０００７】
ここで、従来一般の熱間圧延方式としては、粗圧延機、仕上圧延機としてそれぞれリバーシング・ミル、リバーシング・ウォームミルを適用するか、あるいは粗圧延および仕上圧延兼用の圧延機としてリバーシング・ミルを用いることが多いが、これらの熱間圧延方式では、一般に耳率を改善しようとすれば、特にフランジ成形性の低下を招く問題が生じ、また逆にフランジ成形性を向上させようとすれば耳率を抑えることが困難となり、例えば絞り比１．９において耳率を３％以下に抑えることは困難となる。
【０００８】
一方、耳率を改善するための缶胴材製造方法として、既に特開平５−３１７９１４号では、冷間圧延中途において２回焼鈍を行なう方法が提案されているが、このように冷間圧延中途において２回焼鈍を行なった場合、最終冷間圧延の圧延率を大きくとれないため、強度不足が生じやすいという問題があるほか、焼鈍を２回行なうために製造コストの上昇を招き、さらには製缶時の材料の加工硬化量が大きくなってフランジ成形性が悪化する問題もある。
【０００９】
この発明は以上の事情を背景としてなされたものであって、熱間圧延機としてリバーシング・ミルを用いた場合において、缶胴材として望まれる諸要求を充分に満足し得る材料、すなわち薄肉化を図った場合でも強度とフランジ成形性、しごき性に優れ、しかも深絞りにおける材料の耳率が確実かつ安定して低い缶胴用アルミニウム合金板を製造し得る方法を提供することを基本的な目的とするものである。
【００１０】
【課題を解決するための手段】
前述のような課題を解決するべく、本願発明者等が種々実験・検討を重ねた結果、粗圧延および仕上圧延からなる熱間圧延の諸条件を厳密に規制し、これにより熱間圧延における材料の再結晶状態、特に仕上圧延における各圧延パスでの再結晶状態と立方体方位結晶粒の密度（面積率）等を適切に制御し、かつ得られた熱間圧延板に対し１次冷間圧延を施してから中間焼鈍を行なって、中間焼鈍後の立方体方位結晶粒の密度（面積率）を適切に制御することによって、前述の課題を解決し得ることを見出し、この発明をなすに至ったのである。
【００１１】
具体的には、請求項１の発明の缶胴用アルミニウム合金板の製造方法は、Ｍｇ０．５〜２．０％、Ｍｎ０．５〜２．０％、Ｆｅ０．１〜０．７％、Ｓｉ０．０５〜０．５％を含有し、さらに必要に応じて０．００５〜０．２０％のＴｉを単独でもしくは０．０００１〜０．０５％のＢと組合せて含有し、残部がＡｌおよび不可避的不純物よりなるアルミニウム合金を鋳造した後、５２０〜６３０℃の範囲内の温度で１時間以上の均質化処理を施し、さらにリバーシング・ミルを用いて粗圧延および仕上圧延からなる熱間圧延を行なうにあたり、
（１）３５０〜５９０℃の範囲内の温度で熱間粗圧延を開始し、
（２）熱間粗圧延終了後、熱間仕上圧延を５０ｍｍ以下の板厚、２８０〜４５０℃の範囲内の温度で開始し、かつ熱間仕上圧延の各圧延パスでの圧下率を１０〜８０％の範囲内、各圧延パス間の材料滞留時間を１０分以内として、熱間仕上圧延の各圧延パス（但し最終パスを除く）における次パス開始直前までの再結晶率を９０％以下に制御し、
（３）熱間仕上圧延の各圧延パスにおいてコイル長手方向および幅方向の板温度のばらつきを７０℃以内に制御し、
（４）熱間仕上圧延の終了温度を２３０〜３３０℃の範囲内、熱間仕上圧延終了板厚を１．５〜４．０ｍｍの範囲内とし、
（５）熱間仕上圧延終了直後の２３０〜３３０℃の範囲内の温度から室温までの平均冷却速度を１００℃／ｈｒ以下とし、
（６）以上の（１）〜（５）により、熱間仕上圧延終了後の室温に冷却された状態での再結晶率を９７％以下、立方体方位結晶粒の面積率を０．１〜５０％の範囲内に制御し、
その後、熱間圧延板に対して、２〜５０％の範囲内の圧延率で１次冷間圧延を行ない、さらに中間焼鈍として、１〜１００℃／秒の範囲内の平均昇温速度で３３０〜６２０℃の範囲内の温度に加熱して保持なしもしくは１０分以下の保持を行なって、１〜１００℃／秒の範囲内の平均冷却速度で冷却する連続焼鈍を施して材料を完全再結晶させることにより、立方体方位結晶粒の面積率を１〜７０％の範囲内に制御し、その後さらに５０％以上の圧延率で最終冷間圧延を行なうことを特徴とするものである。
【００１２】
また請求項２の発明の缶胴用アルミニウム合金板の製造方法は、素材アルミニウム合金として、Ｍｇ０．５〜２．０％、Ｍｎ０．５〜２．０％、Ｆｅ０．１〜０．７％、Ｓｉ０．０５〜０．５％を含有し、かつＣｕ０．０５〜０．５％、Ｃｒ０．０５〜０．３％、Ｚｎ０．０５〜０．５％のうちの１種または２種以上を含有し、さらに必要に応じて０．００５〜０．２０％のＴｉを単独でもしくは０．０００１〜０．０５％のＢと組合せて含有し、残部がＡｌおよび不可避的不純物よりなるアルミニウム合金を用い、請求項１で規定するプロセス条件と同様の条件の均質化処理−熱間圧延（粗圧延−仕上圧延）−１次冷間圧延−連続焼鈍−最終冷間圧延のプロセスで製造するものである。
【００１３】
さらに請求項３の発明の缶胴用アルミニウム合金板の製造方法は、素材合金として請求項１で規定する合金と同じアルミニウム合金を用い、かつ均質化処理−熱間圧延（粗圧延−仕上圧延）−１次冷間圧延を請求項１で規定する条件で行ない、その後の焼鈍として、０．１℃／秒以下の平均昇温速度で加熱して２５０〜５００℃の範囲内の温度に０．５時間以上保持して、０．１℃／秒以下の平均冷却速度で冷却するバッチ焼鈍を施し、その後請求項１の方法と同様に５０％以上の圧延率で最終冷間圧延を行なうものである。
【００１４】
そしてまた請求項４の発明の缶胴用アルミニウム合金板の製造方法は、素材アルミニウム合金として請求項２で規定する成分組成と同じ成分組成の合金を用い、請求項３で規定するプロセスで製造するものである。
【００１５】
なお、以上の請求項１〜４の方法において、５０％以上の圧延率で最終冷間圧延を行なった後には、さらに８０〜２００℃の範囲内の温度で０．１〜２４時間保持する最終焼鈍を施しても良く、これを規定したのが請求項５の発明である。
【００１６】
【発明の実施の形態】
先ずこの発明の方法において用いられるアルミニウム合金の成分組成の限定理由について説明する。
【００１７】
Ｍｇ：
Ｍｇの添加は、Ｍｇそれ自体の固溶による強度向上に効果があり、またＭｇの固溶に伴なって加工硬化量の増大による強度向上が期待でき、さらにはＳｉとの共存によるＭｇ₂Ｓｉの時効析出による強度向上も期待でき、したがってＭｇは缶胴材として必要な強度を得るためには不可欠の元素である。またＭｇは、加工時の転位の増殖作用があるため、再結晶粒を微細化させるためにも有効である。但しＭｇ量が０．５％未満では上述の効果が少なく、一方２．０％を越えれば、高強度は容易に得られるものの、ＤＩ加工時の変形抵抗が大きくなって絞り性やしごき性を悪くする。したがってＭｇ量は０．５〜２．０％の範囲内とした。
【００１８】
Ｍｎ：
Ｍｎは強度および成形性の向上に寄与する有効な元素である。特にこの発明で目的としている用途である缶胴材ではＤＩ成形時にしごき加工が加えられるため、とりわけＭｎは重要となる。アルミニウム板のしごき加工においては通常エマルジョンタイプの潤滑剤が用いられているが、Ｍｎ系晶出物が少ない場合には同程度の強度を有していてもエマルジョンタイプ潤滑剤だけでは潤滑能が不足し、ゴーリングと称される擦り疵や焼付きなどの外観不良が発生するおそれがある。ゴーリングは晶出物の大きさ、量、種類に影響されることが知られており、その晶出物を形成するためにＭｎは不可欠な元素である。Ｍｎ量が０．５％未満ではＭｎ系化合物による固体潤滑的な効果が得られず、一方Ｍｎ量が２．０％を越えればＡｌ₆Ｍｎの初晶巨大金属間化合物が発生し、著しく成形性を損なう。そこでＭｎ量は０．５〜２．０％の範囲内とした。
【００１９】
Ｆｅ：
Ｆｅは、Ｍｎの晶出や析出を促進して、アルミニウム基地中のＭｎ固溶量やＭｎ系金属間化合物の分散状態を制御するために必要な元素である。適切な化合物分散状態を得るためには、Ｍｎ添加量に応じてＦｅを添加することが必要である。Ｆｅ量が０．１％未満では適切な化合物分散状態を得ることが困難であり、一方Ｆｅ量が０．７％を越えれば、Ｍｎ添加に伴なって初晶巨大金属間化合物が発生しやすくなり、成形性を著しく損なう。そこでＦｅ量の範囲は０．１〜０．７％とした。
【００２０】
Ｓｉ：
Ｓｉの添加は、Ｍｇ₂Ｓｉ系化合物の析出による時効硬化を通じて缶胴材の強度向上に寄与する。またＳｉは、Ａｌ−Ｍｎ−Ｆｅ−Ｓｉ系金属間化合物を生成して、Ｍｎ系金属間化合物の分散状態を制御するために必要な元素である。Ｓｉ量が０．０５％未満では上記の効果が得られず、一方０．５％を越えれば時効硬化により材料が硬くなりすぎて成形性を阻害する。そこでＳｉ量の範囲は０．０５〜０．５％とした。
【００２１】
Ｔｉ，Ｂ：
通常のアルミニウム合金においては、鋳塊結晶粒微細化のためにＴｉ、あるいはＴｉおよびＢを微量添加することが行なわれており、この発明においても、必要に応じて微量のＴｉを単独で、あるいはＢと組合せて添加しても良い。但しＴｉ量が０．００５％未満ではその効果が得られず、０．２０％を越えれば巨大なＡｌ−Ｔｉ系金属間化合物が晶出して成形性を阻害するため、Ｔｉを添加する場合のＴｉ量は０．００５〜０．２０％の範囲内とした。またＴｉとともにＢを添加すれば鋳塊結晶粒微細化の効果が向上するが、Ｔｉと併せてＢを添加する場合、Ｂ量が０．０００１％未満ではその効果がなく、０．０５％を越えればＴｉ−Ｂ系の粗大粒子が混入して成形性を害することから、ＴｉとともにＢを添加する場合のＢ量は０．０００１〜０．０５％の範囲内とした。
【００２２】
Ｃｕ，Ｃｒ，Ｚｎ：
これらはいずれも強度向上に寄与する元素であり、必要に応じてこれらのうちから選ばれた１種または２種以上が添加される。これらの各元素についてさらに説明する。
【００２３】
Ｃｕ：
Ｃｕは、焼鈍時にアルミニウム基地中に溶体化させておき、塗装焼付処理時にＡｌ−Ｃｕ−Ｍｇ系析出物として析出することによる析出硬化を利用した強度向上に寄与する。Ｃｕ量が０．０５％未満ではその効果が得られず、一方Ｃｕを０．５％を越えて添加した場合には、時効硬化は容易に得られるものの、硬くなりすぎて成形性を阻害し、また耐食性も劣化する。そこでＣｕ量の範囲は０．０５〜０．５％とした。
【００２４】
Ｃｒ；
Ｃｒも強度向上に効果的な元素であるが、０．０５％未満ではその効果が少なく、０．３％を越えれば巨大晶出物生成によって成形性の低下を招くため、好ましくない。そこでＣｒ量の範囲は０．０５〜０．３％とした。
【００２５】
Ｚｎ：
Ｚｎの添加はＡｌ−Ｍｇ−Ｚｎ系粒子の時効析出による強度向上に寄与するが、０．０５％未満ではその効果が得られず、０．５％を越えれば、強度への寄与については問題がないが、耐食性を劣化させる。そこでＺｎ量の範囲は０．０５〜０．５％とした。
【００２６】
以上の各元素の残部はＡｌと不可避不純物とすれば良い。
【００２７】
次にこの発明における製造プロセスを、その作用とともに説明する。
【００２８】
先ず前述のような合金組成を有するアルミニウム合金鋳塊を常法に従ってＤＣ鋳造法（半連続鋳造法）などにより鋳造する。次いでその鋳塊に対して均質化処理を施して、鋳塊の偏析を均質化するとともにＭｎ系の第２相粒子サイズと分布を最適化する。均質化処理温度が５２０℃未満では均質化の効果が不充分であり、一方６３０℃を越えれば共晶融解のおそれがある。均質化処理は１時間未満では均質化が不充分となる。したがって均質化処理は５２０〜６３０℃の範囲内の温度で１時間以上行なう必要がある。なお均質化処理時間の上限は特に規制しないが、経済性を考慮して通常は４８時間以下にすることが好ましい。
【００２９】
均質化処理を施した鋳塊に対しては、熱間圧延を行なう。この熱間圧延は、粗圧延およびそれに続く仕上圧延からなるものである。缶胴材の製造工程中において、熱間圧延の条件は、材料の回復および再結晶挙動に大きな影響を及ぼし、それに伴なって耳率に深く関係する圧延集合組織、特に立方体方位結晶粒の生成に重要な影響を及ぼす。そこでこの発明では、熱間圧延開始温度や熱間圧延終了温度のみならず、仕上圧延での各圧延パスの条件などを厳密に細かく規定することによって、再結晶挙動、ひいては圧延集合組織を厳密に制御している。以下に熱間圧延工程における各条件（１）〜（６）についてさらに詳細に説明する。
【００３０】
（１）熱間圧延開始温度、すなわち粗圧延開始温度を３５０〜５９０℃の範囲内とする。
【００３１】
熱間圧延の開始温度は、熱間圧延中の材料の回復および再結晶の挙動に強い影響を及ぼし、特に最終板の深絞り耳率に深く関係する圧延集合組織の制御に重要な役割を果たしている。熱間粗圧延開始温度が３５０℃未満では圧延集合組織を発達させ易いが、熱間圧延中に板のエッジ割れが生じやすくなり、一方５９０℃を越えた高温で熱間圧延を開始すれば、粗大な結晶粒が生成されやすくなり、板の表面品質が低下する。したがって熱間粗圧延の開始温度は３５０〜５９０℃の範囲内とする必要がある。
【００３２】
（２）熱間粗圧延終了後、熱間仕上圧延を、５０ｍｍ以下の板厚、２８０〜４５０℃の範囲内の温度で開始し、さらに仕上圧延の各圧延パスでの圧下率を１０〜８０％の範囲内、各圧延パス間での材料滞留時間を１０分以内として、仕上圧延の各圧延パス（但し最終パスは除く）における次パス開始直前までの再結晶率を９０％以下、好ましくは３０％以下に制御する。
【００３３】
仕上圧延の開始時の板厚が５０ｍｍを越えれば、仕上圧延のパス回数が増加し、仕上圧延効率が悪くなるから、仕上圧延の開始板厚は５０ｍｍ以下とした。このような５０ｍｍ以下の板厚での仕上圧延中における各圧延パスでの再結晶率は、集合組織の制御に重要な影響を及ぼし、その間の各圧延パスにおける再結晶率を９０％以下、望ましくは３０％以下に制御することによって、熱間圧延終了後の材料の立方体方位密度（具体的には、立方体方位結晶粒の面積率）を高め、最終板の４５°耳を低くして低耳率を達成することが可能となる。なおここで規定している各圧延パスにおける再結晶率は、その圧延パスの開始から次パスでの圧延が開始される直前までに生じる再結晶を素材全体に対する面積率で表わしたものである。ここで、板厚５０ｍｍ以下の仕上圧延での各圧延パスのうち、１パスでも再結晶率が９０％を越えれば、熱間圧延終了後の立方体方位密度が低下して、最終板の４５°耳が高くなってしまう。
【００３４】
上述のように板厚が５０ｍｍ以下の仕上圧延の各圧延パスにおける再結晶率を９０％以下、好ましくは３０％以下に制御するためには、圧延温度と、各圧延パスにおける圧下率、および各圧延パス間での材料滞留時間を適切に制御する必要がある。すなわち、板厚が５０ｍｍ以下の仕上圧延における圧延開始温度を２８０〜４５０℃の範囲内とし、また仕上圧延の各圧延パスでの圧下率を１０〜８０％の範囲内とし、さらに各圧延パス間における材料滞留時間（前の圧延パスにおける圧延終了から次の圧延パスにおける圧延開始までの時間）を１０分以内とする必要がある。
【００３５】
ここで、仕上圧延での圧延開始温度が２８０℃未満では表面品質が劣化するとともにエッジ割れが発生するおそれがある。一方仕上圧延の圧延開始温度が４５０℃を越えれば、再結晶率が上限を越えてしまうおそれがある。また各圧延パスの圧下率が１０％未満では生産性が低下し、一方８０％を越えれば、温度と組合せて再結晶率が９０％以下を維持することが困難となるばかりでなく、表面品質の低下を招くおそれがある。さらに各圧延パス間での材料滞留時間が１０分を越えれば、その滞留期間中に再結晶が進行して、各圧延パスでの再結晶率が上限を越えてしまうおそれがあり、また生産性も低下する。
【００３６】
（３）仕上圧延の各圧延パスにおいて、コイル長手方向および幅方向の板温度のばらつきを７０℃以内に制御する。
【００３７】
ここで、仕上圧延の各圧延パスでのコイル長手方向の温度のばらつきもしくはコイル幅方向の温度のばらつきが７０℃を越えれば、コイル長手方向もしくは幅方向に再結晶率がばらつき、均一な耳率を維持することが困難となってしまう。なおこのようにコイル長手方向、幅方向の板温度のばらつきを７０℃以内に制御するための方法は特に限定されないが、例えば圧延速度を調整して加工発熱を抑制したり、クーラントの量を調整して温度が高くなりやすい部分を重点的に冷却したりすれば良い。
【００３８】
（４）熱間圧延終了温度すなわち仕上圧延終了温度を２３０〜３３０℃の範囲内とし、かつ熱間圧延終了時の板厚を１．５〜４．０ｍｍの範囲内とする。
【００３９】
熱間圧延の終了温度（上がり温度）が２３０℃未満では、表面品質が低下するばかりでなく、第２相粒子周辺での再結晶核生成密度が増加して、その後の再結晶で立方体方位以外の再結晶粒が多くなり、立方体方位結晶粒の面積率を０．１％以上とすることが困難となって、低耳率制御に不利となる。一方熱間圧延終了温度が３３０℃を越えれば、熱間圧延終了後室温まで冷却する間に完全再結晶もしくはそれに近い再結晶状態となり、室温冷却状態での再結晶率を９７％以下とすることが困難となってしまう。また熱間圧延終了時の板厚（上がり板厚）が１．５ｍｍ未満では、熱間圧延機における板厚精度の制御が困難となり、一方熱間圧延終了板厚が４．０ｍｍを越えれば、中間焼鈍後の最終冷間圧延において圧延率が高くなり過ぎ、高強度は容易に得られるものの、４５°耳が高くなって、耳率が大きくなってしまう。
【００４０】
（５）熱間圧延終了直後（仕上圧延終了温度）の２３０〜３３０℃の範囲内の温度から室温までの平均冷却速度を１００℃／時間以下とする。
【００４１】
熱間圧延終了直後の上り材（コイル）の２３０〜３３０℃の範囲内の温度から室温までの冷却過程、特に１００℃までの冷却過程は、立方体方位の結晶粒の核生成が生じる過程であり、この間の冷却速度が１００℃／時間を越える場合には、立方体方位の結晶粒の核生成が不充分となり、立方体方位結晶粒面積率０．１％以上を確保することが困難となって、最終板の低耳率制御に不利となる。なお熱間圧延終了直後の２３０〜３３０℃の範囲内の温度から室温までの平均冷却速度の下限は特に限定しないが、１℃／時間以上とすることが好ましい。その間の冷却速度が１℃／時間未満の場合は、ほぼ完全に再結晶してしまい、室温まで冷却した状態での再結晶率を９７％以下とすることが困難となるおそれがある。
【００４２】
（６）室温まで冷却した状態での熱間圧延上がり板（熱延板）の再結晶率を９７％以下（したがって部分再結晶状態に相当する）とし、かつ立方体方位結晶粒の面積率を０．１〜５０％の範囲内とする。
【００４３】
熱間圧延上り板の室温まで冷却した状態での再結晶率と立方体方位結晶粒の面積率の規制は、この発明の方法において重要なポイントであり、これらの値は最終板の低耳率制御と外観欠陥に大きな影響を及ぼす。すなわち、熱間圧延上りの２３０〜３３０℃の範囲内の温度から室温まで冷却する間に自己焼鈍が進んで、再結晶率が９７％を越えてしまった場合（すなわち完全再結晶状態もしくはそれに近い再結晶状態）には、その後の１次冷間圧延と中間焼鈍により立方体方位の結晶組織を増強させる効果が得られなくなり、そのため最終板を低耳率に制御することが困難となり、また同時に最終板の結晶粒の粗大化を招いて製缶時の肌荒れやフローライン等の外観欠陥が発生しやすくなる。したがって室温まで冷却した状態での再結晶率を９７％以下に規制する必要がある。そしてこの範囲内でも特に再結晶率を７５％以下に規制することが好ましい。また立方体方位結晶粒の面積率が０．１％未満でも、その後の１次冷間圧延と中間焼鈍により立方体方位の結晶組織を増強させることが困難となり、最終板の４５°耳が高くなって低耳率を達成することが困難となる。一方立方体方位結晶粒の面積率が５０％を越えれば、立方体方位結晶粒が過剰となり、最終冷間圧延後の最終板でも０°−９０°耳が残り、製缶時のトラブルの原因となる。
【００４４】
なお上述のように室温まで冷却した状態での再結晶率および立方体方位結晶粒面積率には、熱間圧延諸条件、すなわち前述の（１）〜（５）の条件と合金の成分組成が影響を与えるから、これらを相互の関係のもとに適切に調整することによって室温での再結晶率を９７％以下、立方体方位結晶粒面積率を０．１〜５０％に制御することができる。
【００４５】
なおまた、上述のような熱延板を得るための熱間圧延設備としては、粗圧延機、仕上圧延機のそれぞれにリバーシング・ミル（リバーシング・ウォームミルを含む）を用いるかまたは粗圧延と仕上圧延兼用のリバーシング・ミル（リバーシング・ウォームミルを含む）を用いることとする。
【００４６】
以上の（１）〜（６）の条件を満たすようにして得られた部分再結晶状態の熱延板に対しては、圧延率が２〜５０％の範囲内の１次冷間圧延を施す。このように部分再結晶状態の熱延板に対し１次冷間圧延を施して熱延板に適切な歪みを与えることにより、その後の焼鈍で立方体方位の結晶粒の生成、成長を促進させるとともに、立方体方位以外の方位の結晶粒の核生成、成長を抑制する効果が得られる。
【００４７】
ここで、熱延板に対する１次冷間圧延の圧延率が２％未満では、歪み量不足により立方体方位の結晶粒の生成、成長を加速する効果および立方体方位以外の結晶粒の生成、成長を抑制する効果が不充分となり、また実際の工業生産では２％未満のわずかな圧下量のコントロールは困難となる。一方１次冷間圧延の圧延率が５０％を越えれば、導入された多量の歪により立方体方位の結晶粒やその核も破壊されてしまうため、立方体方位結晶粒組織を増強することが困難となり、最終板の耳率低減効果が得られなくなり、さらには最終冷間圧延率が相対的に減少し、充分な強度を確保することが困難となる。したがって熱延板に対する１次冷間圧延における圧延率は２〜５０％の範囲内とした。ここで、特にこの発明においては、１次冷間圧延の圧延率が２〜５０％という広い範囲で許容しながらも、低耳率を達成し得ることが重要であり、このような広い範囲内で１次冷間圧延率を最適に調整することによって、最終板における低耳率のみならず、前述の缶胴材に要求される４要素のバランスを向上させることが可能となった。なおこのように１次冷間圧延率に広い範囲が許容されるようになったのは、既に述べたように熱間圧延の諸条件を厳密に規制して、耳率制御に有利となるように熱間圧延工程での再結晶状態および立方体方位結晶粒面積率を適切に制御したことによるのである。
【００４８】
前述のように熱延板に対して圧延率２〜５０％の１次冷間圧延を施した後には、連続焼鈍（ＣＡＬ）もしくはバッチ焼鈍によって中間焼鈍を施す。この中間焼鈍は、材料を完全に再結晶させ、最終冷間圧延後の最終板の耳率を低くするために必要な工程である。
【００４９】
１次冷間圧延後の中間焼鈍に連続焼鈍を適用する場合、その連続焼鈍は、１〜１００℃／秒の範囲内の平均昇温速度で３３０〜６２０℃の範囲内の温度に加熱し、保持なしもしくは１０分以下の保持の後、１〜１００℃／秒の範囲内の平均冷却速度で冷却する条件とする。ここで、平均昇温速度、平均冷却速度が１℃／秒未満では、連続焼鈍（ＣＡＬ）方式においては生産性の著しい低下を招き、また１００℃／秒を越える平均昇温速度、平均冷却速度は立方体方位の結晶粒の形成に不利となる。また加熱到達温度が３３０℃未満では再結晶が生じにくく、一方６２０℃を越える高温では共晶融解が生じるおそれがある。さらに３３０〜６２０℃に１０分を越えて保持することは、連続焼鈍の生産性を阻害する。
【００５０】
一方、一次冷間圧延後の中間焼鈍としてバッチ焼鈍を適用する場合、平均昇温速度０．１℃／秒以下で２５０〜５００℃の範囲内の温度に加熱し、その範囲内の温度で０．５時間以上保持し、平均冷却速度０．１℃／秒以下で冷却する。ここで、平均昇温速度および平均冷却速度が０．１℃／秒を越えれば、バッチ焼鈍方式では熱延板コイル全体を均一に加熱もしくは冷却できなくなる問題が生じる。また加熱保持温度が２５０℃未満では完全に再結晶させることが困難となり、一方５００℃を越える高温では再結晶核が粗大となって、製缶時に肌荒れやフローラインなどの表面欠陥が発生しやすくなる。また加熱保持の時間が０．５時間未満では完全に再結晶させることが困難であり、また熱延板のコイルの全体を均一に加熱することが困難となる。なおバッチ焼鈍の場合の加熱保持時間の上限は特に定めないが、通常は経済性の観点から、２４時間以内とする。
【００５１】
さらに、最終板の低耳率を実現するためには、前述のような連続焼鈍もしくはバッチ焼鈍による中間焼鈍を施した後の状態で、立方体方位結晶粒の面積率を１〜７０％の範囲内とする必要がある。中間焼鈍後の状態で立方体方位結晶粒の面積率が１％未満では、最終板の４５°耳が高くなりやすく、一方７０％を越えれば立方体方位結晶粒が過剰となって０°−９０°耳が高くなりやすくなる。
【００５２】
前述のようにして中間焼鈍を施した後には、最終板厚としかつ必要な強度を得るために、５０％以上の圧延率で、最終冷間圧延を施す。ここで、最終冷間圧延の圧延率が５０％未満では、加工硬化による強度上昇が少なく、缶胴材用の最終板に必要な強度を得ることが困難である。
【００５３】
最終冷間圧延後の板は、これを最終板としてそのままＤＩ成形に供しても良いが、最終冷間圧延後の板に必要に応じて８０〜２００℃の範囲内の温度で０．５〜２４時間の最終焼鈍を行なっても良い。この最終焼鈍は、延性の回復による成形性の向上を目的としたものであるが、その温度が８０℃未満では成形性の向上効果が充分に得られず、一方２００℃を越えれば軟化による強度低下が大きくなり、また焼鈍時間が０．５時間未満では成形性向上効果を充分に得ることができず、さらに焼鈍時間が２４時間を越えれば、成形性向上効果が飽和し、生産性、経済性を損なうだけである。なお積極的に最終焼鈍を行なわない場合でも、最終冷間圧延を高速で行なうことにより発生する加工熱を利用して、前記同様な焼鈍効果を得ることができる。
【００５４】
【実施例】
表１に示す合金記号Ａ〜Ｅの各合金について、常法に従ってＤＣ鋳造法によりスラブに鋳塊した。その後、均質化処理を施した後、リバーシング・ミルを用いて熱間圧延（粗圧延−仕上圧延）を施した。均質化処理および熱間圧延の詳細な条件を表２〜表４の製造番号１〜７に示す。さらに室温まで冷却した後の熱延板に対し、１次冷間圧延を施した後、中間焼鈍として連続焼鈍もしくはバッチ焼鈍を施し、その後最終冷間圧延を行なった。なお最終冷間圧延後には、製造番号１，３，６の場合を除いて最終焼鈍を施した。１次冷間圧延後の詳細な条件を表５の製造番号１〜７に示す。
【００５５】
なお熱間仕上圧延終了後の室温に冷却した状態で再結晶率を調べるとともに、立方体方位結晶粒の面積率を調べたので、その結果を表３、表４中に示す。また中間焼鈍後の状態でも立方体方位結晶粒の面積率を調べたので、その結果を表５中に示す。ここで、再結晶率はＯＩＭ（ＯｒｉｅｎｔａｔｉｏｎＩｍａｇｉｎｇＭｉｃｒｏｓｃｏｐｙ）方位解析顕微鏡のスキャン画像から求めた。また立方体方位結晶粒の面積率の測定については、同じくＯＩＭ方位解析顕微鏡を用いて結晶方位の特定を行ない、立方体方位の中心位置から±１５°の範囲内の結晶回転を持つすべての結晶粒、核を立方体方位粒とみなし、その面積率を定めた。
【００５６】
以上のようにして得られた缶胴用のアルミニウム合金板について、元板の機械的性質（引張強さＴＳ、耐力ＹＳ、伸びＥＬ）および耳率を調べ、さらに塗装焼付（ベーキング）を想定した２００℃×２０分の熱処理を行なった後の機械的性質およびＤＩ成形性を調べた。ここで、元板についての耳率は、ポンチ径４８ｍｍ、ブランク径９３ｍｍ、クリアランス３０％の条件にてカップ深絞り試験を行なって調べた。そして耳率の平均値は、コイル長手方向と幅方向で等間隔にそれぞれ５点、合計２５カ所からサンプルを採取し、その最大値と最小値の差をばらつきとした。ここで耳率の平均値が３％を越えれば、製缶中に缶切れなどのトラブルを引き起こしやすくなり、また耳率のばらつきが３％を越えれば、製缶の安定性を阻害するおそれがある。
【００５７】
一方ＤＩ缶成形性の指標としては、
（１）缶切れ性については苛酷なしごき成形を連続１００００缶行なったときの破断缶の発生状況、
（２）フランジ成形性に相当する口拡げ性については４段ネッキング後のフランジ成形性、
（３）耐圧性については４段ネッキング、フランジング後の缶胴体の座屈強度、
（４）シーミング性についてはフランジング後、蓋とのシーミング性、
（５）外観欠陥についてはＤＩ缶の缶胴壁の圧延方向に沿ったフローライン状の外観欠陥およびＤＩ方向に発生する縦筋、
をそれぞれ調べ、これらの評価項目を１〜５までの５段階のランクで相対評価した。ここで、ＤＩ成形性の評価ランク数値は高いほど良好であり、ランク３以上で合格レベルと評価できる。
【００５８】

【００５９】
【表２】

【００６０】
【表３】

【００６１】
【表４】

【００６２】
【表５】

【００６３】
【表６】

【００６４】
表１〜表６において、製造番号１〜４はいずれもこの発明で規定する成分組成範囲内の合金について、この発明で規定する製造プロセス条件を満足して製造したものであり、この場合は表６に示すように、いずれも耳率が３％を確実に下廻って充分な低耳率を達成でき、かつベーキング後の耐力が２４０ＭＰａ以上で充分な強度を有しており、しかもＤＩ缶成形性も優れていることが明らかである。
【００６５】
一方製造番号５，６は、いずれも合金の成分組成はこの発明で規定する範囲内であるが、製造プロセス条件がこの発明で規定する範囲から外れたものである。
【００６６】
すなわち製造番号５のプロセスは、熱間圧延終了温度に対応する仕上圧延３パス目の温度が１９０℃と低く、この場合は熱間圧延終了後室温に冷却した状態での立方体方位結晶粒の面積率が０．１％を下廻り、また中間焼鈍後の立方体方位結晶粒の面積率も０．７％と低く、そのため耳率が平均で６．１％と高くなってしまい、缶切れ性が著しく劣っていた。
【００６７】
また製造番号６のプロセスは、熱間仕上圧延の開始温度が４６３℃と高く、また仕上圧延４パス目の再結晶率が９３％と高く、さらに熱間圧延終了温度に対応する仕上圧延５パス目の温度が３４０℃と高く、さらに仕上圧延４パス目の材料滞留時間が７１３秒と高く、また１次冷間圧延も行なわなかった例であり、この場合は熱間圧延終了後室温に冷却した状態で完全再結晶してしまい、また４パス目のコイル温度のばらつきが７０℃を越えてしまった。そしてこの場合は耳率が高く、特に耳率のばらつきが４．３％と著しく大きく、缶切れ性、外観欠陥評価が劣っていた。
【００６８】
また製造番号６は、Ｍｇ量が０．４６％とこの発明で規定する範囲を外れた合金Ｅを用いた例であり、この場合はベーキング後の強度が低く、また耳率も高く、さらにＤＩ成形性も劣っていた。
【００６９】
【発明の効果】
前述の実施例からも明らかなように、この発明の方法によれば、ＤＩ缶胴用材料として要求される４要素、すなわち耳率とフランジ成形性、しごき性、強度のバランスが優れたアルミニウム合金板を確実かつ安定して得ることができる。特にこの発明の方法の場合、熱間圧延条件を細かく制御することにより、低耳率を確保しながらも中間焼鈍を挟んでの２回の冷間圧延のうちの１次の冷間圧延の圧延率を広い範囲で調整することが可能となり、そのため低耳率と高い強度とを同時かつ容易に得ることが可能となった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a can body for a two-piece aluminum can by DI processing (drawing-ironing processing), that is, a method for producing an Al-Mg-Mn-based aluminum alloy plate used for a DI can body, and particularly has a low deep drawing ear and is coated. The present invention relates to a method for producing an aluminum alloy plate for a DI can body having high strength after baking and excellent moldability during DI processing and formability after baking.
[0002]
[Prior art]
In general, as a manufacturing process for 2-piece aluminum cans, the can body material is subjected to DI molding by deep drawing and ironing to form a can body shape, then trimmed to a predetermined size, and then degreased and washed. Furthermore, painting and printing are performed and baking (baking) is performed, then necking and flanging are performed on the can body edge, and then seaming processing is performed together with a separately formed can lid (can end). It is normal to go into cans.
[0003]
Conventionally, a hard plate of JIS 3004 alloy, which is an Al-Mg-Mn alloy, has been widely used as a raw material (can body material) for a DI can thus manufactured. This 3004 alloy is excellent in ironing workability and exhibits relatively good formability even when cold-rolled at a high rolling rate in order to increase strength, and is therefore suitable as a DI can body. Has been.
[0004]
As a method of manufacturing such a 3004 alloy hard plate for a DI can body, after casting by a DC casting method or the like, the ingot is subjected to homogenization treatment, and further subjected to hot rolling and cold rolling to a predetermined plate. A method is generally used in which the thickness is increased and intermediate annealing is performed before or during the cold rolling in the process.
[0005]
By the way, it is strongly desired to reduce the thickness of the DI can body mainly for the purpose of reducing the material cost and reducing the weight. In order to reduce the wall thickness in this way, it is indispensable to increase the strength of the material in order to avoid the problem of reduced buckling strength of the can caused by the reduction in thickness.
[0006]
In addition, the DI can body material is strongly desired not only to have a high strength for thinning as described above, but also to have a low ear rate during DI molding. That is, a low ear rate at the time of DI molding is required from the standpoint of improving the yield at the time of DI molding and preventing can barrel breakage caused by ear can cut of the can barrel. In addition, flange formability (mouth spreadability) and ironability (can tearability) at the time of DI can production are also important, and these ear ratios, flange formability, ironability, and strength are required for can bodies. It can be called four main elements, and it is strongly desired to improve these four elements in a balanced manner. In particular, it is difficult to control the ear rate among these four elements. Therefore, appropriate control of the ear rate is an extremely important issue for improving the balance of these four elements.
[0007]
Here, as a conventional general hot rolling method, a reversing mill and a reversing worm mill are applied as a roughing mill and a finishing mill, respectively, or a reversing as a rolling mill for both roughing and finishing rolling.・ In many cases, mills are used. However, in these hot rolling methods, in general, if the ear rate is to be improved, there is a problem that particularly deteriorates the flange formability, and conversely, the flange formability is improved. In this case, it is difficult to suppress the ear rate. For example, it is difficult to suppress the ear rate to 3% or less at the aperture ratio of 1.9.
[0008]
On the other hand, as a method for manufacturing a can body material for improving the ear rate, Japanese Patent Laid-Open No. 5-317914 has already proposed a method of performing annealing twice in the middle of cold rolling. When annealing is performed twice, the rolling ratio of the final cold rolling cannot be increased, so that there is a problem that the strength is likely to be insufficient. Further, the annealing is performed twice, resulting in an increase in manufacturing cost, and further There is also a problem that the work hardening amount of the material at the time of the can increases and the flange formability deteriorates.
[0009]
The present invention has been made against the background described above, and when a reversing mill is used as a hot rolling mill, the material that can sufficiently satisfy various requirements desired as a can body material, that is, thinning. It is essential to provide a method that can produce an aluminum alloy plate for a can body that is excellent in strength, flange formability and squeezing ability, and has a reliable and stable material ear ratio in deep drawing. It is the purpose.
[0010]
[Means for Solving the Problems]
As a result of various experiments and examinations by the inventors of the present application in order to solve the problems as described above, various conditions of hot rolling including rough rolling and finish rolling are strictly regulated, and thereby, materials in hot rolling , Especially the recrystallization state in each rolling pass in finish rolling and the density (area ratio) of cubic orientation grains, etc. are appropriately controlled, and primary cold rolling is performed on the obtained hot rolled sheet It was found that the above-mentioned problems can be solved by appropriately controlling the density (area ratio) of the cubic-oriented crystal grains after the intermediate annealing by performing the intermediate annealing. It is.
[0011]
Specifically, the manufacturing method of the aluminum alloy plate for can bodies of the invention of claim 1 is Mg 0.5-2.0%, Mn 0.5-2.0%, Fe 0.1-0.7%, SiO 0.05 to 0.5%, and optionally 0.005 to 0.20% Ti alone or in combination with 0.0001 to 0.05% B, with the balance being Al and After casting an aluminum alloy composed of inevitable impurities, it is subjected to homogenization treatment for 1 hour or more at a temperature in the range of 520 to 630 ° C., and further hot rolling comprising rough rolling and finish rolling using a reversing mill. In doing
(1) Hot rough rolling is started at a temperature within the range of 350 to 590 ° C.
(2) After completion of hot rough rolling, hot finish rolling is started at a thickness of 50 mm or less and at a temperature within the range of 280 to 450 ° C., and the rolling reduction in each rolling pass of hot finish rolling is 10 to 10. Within 80% range, the material residence time between each rolling pass is within 10 minutes, and the recrystallization rate immediately before the start of the next pass in each rolling pass of hot finish rolling (excluding the final pass) is 90% or less. Control
(3) In each rolling pass of hot finish rolling, the variation in the plate temperature in the coil longitudinal direction and the width direction is controlled within 70 ° C.,
(4) End temperature of hot finish rolling is in the range of 230 to 330 ° C., and finish plate thickness of hot finish rolling is in the range of 1.5 to 4.0 mm.
(5) The average cooling rate from the temperature in the range of 230 to 330 ° C. immediately after completion of hot finish rolling to room temperature is 100 ° C./hr or less,
(6) By the above (1) to (5), the recrystallization rate in the state cooled to room temperature after the hot finish rolling is completed is 97% or less, and the area ratio of the cubic orientation crystal grains is 0.1 to 50. Control within the range of%,
Thereafter, the hot-rolled sheet is subjected to primary cold rolling at a rolling rate within a range of 2 to 50%, and further as an intermediate annealing, with an average temperature increase rate within a range of 1 to 100 ° C./sec. Completely recrystallized by heating to a temperature in the range of ~ 620 ° C without holding or holding for 10 minutes or less, followed by continuous annealing to cool at an average cooling rate in the range of 1-100 ° C / second Thus, the area ratio of the cubic-oriented crystal grains is controlled within a range of 1 to 70%, and then the final cold rolling is performed at a rolling rate of 50% or more.
[0012]
Moreover, the manufacturing method of the aluminum alloy plate for can bodies of invention of Claim 2 is Mg0.5-2.0%, Mn0.5-2.0%, Fe0.1-0.7% as raw material aluminum alloy, Si 0.05 to 0.5% and Cu 0.05 to 0.5%, Cr 0.05 to 0.3%, Zn 0.05 to 0.5%, or one or more of them Further, if necessary, an aluminum alloy containing 0.005 to 0.20% Ti alone or in combination with 0.0001 to 0.05% B, with the balance being Al and inevitable impurities is used. The process is the same as the process conditions defined in claim 1-hot rolling (rough rolling-finish rolling)-primary cold rolling-continuous annealing-final cold rolling process. .
[0013]
Furthermore, the manufacturing method of the aluminum alloy plate for can bodies of the invention of claim 3 uses the same aluminum alloy as the alloy specified in claim 1 as the material alloy, and homogenization treatment-hot rolling (rough rolling-finish rolling). The first cold rolling is performed under the conditions specified in claim 1 and the subsequent annealing is performed by heating at an average heating rate of 0.1 ° C./second or less to a temperature in the range of 250 to 500 ° C. Hold for 5 hours or more, perform batch annealing to cool at an average cooling rate of 0.1 ° C./second or less, and then perform final cold rolling at a rolling rate of 50% or more as in the method of claim 1. is there.
[0014]
And the manufacturing method of the aluminum alloy plate for can bodies of invention of Claim 4 uses the alloy of the same component composition as the component composition prescribed | regulated in Claim 2 as a raw material aluminum alloy, and it manufactures it by the process prescribed | regulated in Claim 3. Is.
[0015]
In addition, in the method of the above Claims 1-4, after performing the final cold rolling at a rolling rate of 50% or more, the final holding is further performed at a temperature within the range of 80 to 200 ° C. for 0.1 to 24 hours. Annealing may be performed, and this is defined in the invention of claim 5.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
First, the reasons for limiting the component composition of the aluminum alloy used in the method of the present invention will be described.
[0017]
Mg:
The addition of Mg is effective in improving the strength due to the solid solution of Mg itself, and can be expected to improve the strength by increasing the work hardening amount due to the solid solution of Mg, and further, Mg ₂ Si by coexisting with Si. Therefore, Mg is an indispensable element for obtaining the strength required as a can body material. Further, Mg has an effect of multiplying dislocations at the time of processing, and is therefore effective for making recrystallized grains finer. However, if the amount of Mg is less than 0.5%, the above-mentioned effect is small. On the other hand, if it exceeds 2.0%, high strength can be easily obtained, but the deformation resistance during DI processing increases and the drawability and squeezing property are improved. Make it worse. Therefore, the Mg content is set in the range of 0.5 to 2.0%.
[0018]
Mn:
Mn is an effective element that contributes to improvement in strength and formability. In particular, Mn is particularly important for a can body material, which is the intended use of the present invention, because ironing is applied during DI molding. Emulsion-type lubricants are usually used in ironing of aluminum plates, but if there are few Mn-based crystallized products, even if they have the same level of strength, the emulsion-type lubricants alone are not sufficient for lubrication. In addition, appearance defects such as scuffing and seizure called goling may occur. Goling is known to be affected by the size, amount, and type of crystallized matter, and Mn is an indispensable element for forming the crystallized product. If the amount of Mn is less than 0.5%, the effect of solid lubrication by the Mn-based compound cannot be obtained. On the other hand, if the amount of Mn exceeds 2.0%, a primary intermetallic compound of Al ₆ Mn is generated, which is markedly formed. Impairs sex. Therefore, the amount of Mn is set in the range of 0.5 to 2.0%.
[0019]
Fe:
Fe is an element necessary for accelerating crystallization and precipitation of Mn to control the amount of Mn solid solution in the aluminum matrix and the dispersion state of the Mn-based intermetallic compound. In order to obtain an appropriate compound dispersion state, it is necessary to add Fe according to the amount of Mn added. If the Fe content is less than 0.1%, it is difficult to obtain an appropriate compound dispersion state. On the other hand, if the Fe content exceeds 0.7%, a primary giant intermetallic compound is likely to be generated with the addition of Mn. Thus, the moldability is remarkably impaired. Therefore, the range of Fe content is set to 0.1 to 0.7%.
[0020]
Si:
The addition of Si contributes to improvement of the strength of the can body material through age hardening by precipitation of Mg ₂ Si-based compounds. Si is an element necessary for generating an Al—Mn—Fe—Si intermetallic compound and controlling the dispersion state of the Mn intermetallic compound. If the amount of Si is less than 0.05%, the above effect cannot be obtained. On the other hand, if it exceeds 0.5%, the material becomes too hard due to age hardening, thereby impairing the moldability. Therefore, the range of Si content is set to 0.05 to 0.5%.
[0021]
Ti, B:
In a normal aluminum alloy, a small amount of Ti or Ti and B is added for ingot crystal grain refinement. Also in this invention, a small amount of Ti is used alone or as required. B may be added in combination with B. However, if the amount of Ti is less than 0.005%, the effect cannot be obtained, and if it exceeds 0.20%, a huge Al-Ti intermetallic compound crystallizes and inhibits formability. The amount of Ti was within the range of 0.005 to 0.20%. Moreover, if B is added together with Ti, the effect of refining the ingot crystal grains is improved. However, when B is added together with Ti, the effect is not obtained if the amount of B is less than 0.0001%. If exceeding, Ti—B based coarse particles are mixed to impair the moldability. Therefore, the amount of B in the case of adding B together with Ti is set in the range of 0.0001 to 0.05%.
[0022]
Cu, Cr, Zn:
These are all elements that contribute to strength improvement, and one or more selected from these are added as necessary. Each of these elements will be further described.
[0023]
Cu:
Cu is in solution in the aluminum matrix during annealing, and contributes to strength improvement using precipitation hardening by depositing as an Al-Cu-Mg-based precipitate during coating baking. If the amount of Cu is less than 0.05%, the effect cannot be obtained. On the other hand, if Cu is added in excess of 0.5%, age hardening can be easily obtained, but it becomes too hard and inhibits formability. Moreover, corrosion resistance also deteriorates. Therefore, the range of Cu content is set to 0.05 to 0.5%.
[0024]
Cr;
Cr is also an element effective in improving the strength. However, if it is less than 0.05%, the effect is small, and if it exceeds 0.3%, formability is reduced due to the formation of giant crystals, which is not preferable. Therefore, the range of Cr content is set to 0.05 to 0.3%.
[0025]
Zn:
Addition of Zn contributes to strength improvement by aging precipitation of Al—Mg—Zn-based particles. However, if it is less than 0.05%, the effect cannot be obtained, and if it exceeds 0.5%, there is a problem regarding contribution to strength. There is no, but deteriorates the corrosion resistance. Therefore, the range of Zn content is set to 0.05 to 0.5%.
[0026]
The balance of the above elements may be Al and inevitable impurities.
[0027]
Next, the manufacturing process in this invention is demonstrated with the effect | action.
[0028]
First, an aluminum alloy ingot having the above alloy composition is cast by a DC casting method (semi-continuous casting method) or the like according to a conventional method. The ingot is then homogenized to homogenize the ingot segregation and optimize the Mn-based second phase particle size and distribution. If the homogenization treatment temperature is less than 520 ° C, the effect of homogenization is insufficient, while if it exceeds 630 ° C, eutectic melting may occur. If the homogenization treatment is less than 1 hour, homogenization is insufficient. Therefore, it is necessary to carry out the homogenization treatment for 1 hour or more at a temperature in the range of 520 to 630 ° C. The upper limit of the homogenization time is not particularly limited, but it is usually preferably 48 hours or less in consideration of economy.
[0029]
Hot rolling is performed on the ingot subjected to the homogenization treatment. This hot rolling consists of rough rolling and subsequent finish rolling. During the manufacturing process of can bodies, the conditions of hot rolling have a great influence on the recovery and recrystallization behavior of the material, which is accompanied by the formation of rolling textures, especially cube-oriented grains, which are closely related to the ear ratio. Has an important impact on Therefore, in the present invention, not only the hot rolling start temperature and the hot rolling end temperature but also the conditions of each rolling pass in finish rolling are strictly defined, so that the recrystallization behavior and thus the rolling texture is strictly regulated. I have control. Below, each condition (1)-(6) in a hot rolling process is demonstrated still in detail.
[0030]
(1) The hot rolling start temperature, that is, the rough rolling start temperature is set within the range of 350 to 590 ° C.
[0031]
The starting temperature of hot rolling has a strong influence on the material recovery and recrystallization behavior during hot rolling, and plays an important role in controlling the rolling texture, which is particularly related to the deep drawing ratio of the final plate. Yes. If the hot rough rolling start temperature is less than 350 ° C., it is easy to develop a rolling texture, but edge cracking of the plate is likely to occur during hot rolling, while if hot rolling is started at a high temperature exceeding 590 ° C., Coarse crystal grains are easily generated, and the surface quality of the plate is lowered. Therefore, the start temperature of hot rough rolling needs to be in the range of 350 to 590 ° C.
[0032]
(2) After completion of hot rough rolling, hot finish rolling is started at a thickness of 50 mm or less and at a temperature within the range of 280 to 450 ° C., and the rolling reduction in each rolling pass of finish rolling is 10 to 80. %, The material residence time between each rolling pass is 10 minutes or less, and the recrystallization rate immediately before the start of the next pass in each rolling pass of the finish rolling (excluding the final pass) is preferably 90% or less, preferably Control to 30% or less.
[0033]
If the plate thickness at the start of finish rolling exceeds 50 mm, the number of passes of finish rolling increases and the finish rolling efficiency deteriorates. Therefore, the start plate thickness of finish rolling is set to 50 mm or less. The recrystallization rate in each rolling pass during finish rolling with a sheet thickness of 50 mm or less has an important influence on the control of the texture, and the recrystallization rate in each rolling pass during that period is desirably 90% or less. Is controlled to 30% or less, thereby increasing the cube orientation density (specifically, the area ratio of the cubic orientation crystal grains) of the material after hot rolling, and lowering the 45 ° ear of the final plate to lower the ear. The rate can be achieved. In addition, the recrystallization rate in each rolling pass prescribed | regulated here represents the recrystallization produced from the start of the rolling pass to just before the start of the rolling by the next pass in the area ratio with respect to the whole raw material. Here, if the recrystallization rate exceeds 90% in each rolling pass in the finish rolling with a plate thickness of 50 mm or less, the cube orientation density after the hot rolling is finished, and the final plate is 45 °. Ears get higher.
[0034]
As described above, in order to control the recrystallization rate in each rolling pass of finish rolling with a plate thickness of 50 mm or less to 90% or less, preferably 30% or less, the rolling temperature, the reduction rate in each rolling pass, and each It is necessary to appropriately control the material residence time between rolling passes. That is, the rolling start temperature in finish rolling with a sheet thickness of 50 mm or less is in the range of 280 to 450 ° C., the rolling reduction in each rolling pass of finish rolling is in the range of 10 to 80%, and between each rolling pass It is necessary to set the material residence time in (the time from the end of rolling in the previous rolling pass to the start of rolling in the next rolling pass) within 10 minutes.
[0035]
Here, if the rolling start temperature in finish rolling is less than 280 ° C., the surface quality may deteriorate and edge cracks may occur. On the other hand, if the rolling start temperature of finish rolling exceeds 450 ° C., the recrystallization rate may exceed the upper limit. Further, when the rolling reduction of each rolling pass is less than 10%, the productivity is lowered. On the other hand, when it exceeds 80%, not only is it difficult to maintain the recrystallization rate below 90% in combination with the temperature, but also the surface quality. There is a risk of lowering. Furthermore, if the material residence time between the rolling passes exceeds 10 minutes, recrystallization proceeds during the residence period, and the recrystallization rate in each rolling pass may exceed the upper limit, and productivity is increased. Also decreases.
[0036]
(3) In each rolling pass of finish rolling, variation in the plate temperature in the coil longitudinal direction and width direction is controlled within 70 ° C.
[0037]
Here, if the temperature variation in the coil longitudinal direction or the temperature variation in the coil width direction in each rolling pass of finish rolling exceeds 70 ° C., the recrystallization rate varies in the coil longitudinal direction or the width direction, and the uniform ear ratio It becomes difficult to maintain. In addition, the method for controlling the variation in the plate temperature in the coil longitudinal direction and the width direction within 70 ° C. is not particularly limited as described above. For example, the processing speed is suppressed by adjusting the rolling speed, or the amount of the coolant is adjusted. Then, it is sufficient to cool the part where the temperature is likely to rise.
[0038]
(4) The hot rolling end temperature, that is, the finish rolling end temperature is in the range of 230 to 330 ° C., and the plate thickness at the end of the hot rolling is in the range of 1.5 to 4.0 mm.
[0039]
When the end temperature (rising temperature) of hot rolling is less than 230 ° C., not only the surface quality is deteriorated, but also the recrystallization nucleation density around the second phase particles is increased, and the subsequent recrystallization is not in the cubic orientation. The number of recrystallized grains increases, and it becomes difficult to make the area ratio of cubic-oriented crystal grains 0.1% or more, which is disadvantageous for low ear ratio control. On the other hand, if the hot rolling end temperature exceeds 330 ° C., it will be completely recrystallized or recrystallized while cooling to room temperature after hot rolling is completed, and the recrystallization rate in the room temperature cooling state shall be 97% or less. Becomes difficult. If the plate thickness at the end of hot rolling (rising plate thickness) is less than 1.5 mm, it is difficult to control the thickness accuracy in the hot rolling mill, while if the plate thickness after hot rolling exceeds 4.0 mm, In the final cold rolling after the intermediate annealing, the rolling rate becomes too high and high strength can be easily obtained, but the 45 ° ear becomes high and the ear rate becomes large.
[0040]
(5) Immediately after the end of hot rolling (finish rolling end temperature), the average cooling rate from a temperature in the range of 230 to 330 ° C. to room temperature is set to 100 ° C./hour or less.
[0041]
The cooling process of the ascending material (coil) immediately after the end of hot rolling from a temperature in the range of 230 to 330 ° C. to room temperature, in particular, the cooling process to 100 ° C. is a process in which nucleation of cubic oriented crystal grains occurs. When the cooling rate during this period exceeds 100 ° C./hour, the nucleation of cubic-oriented crystal grains becomes insufficient, and it becomes difficult to ensure a cubic-oriented crystal grain area ratio of 0.1% or more. It is disadvantageous for low ear rate control of the final board. In addition, although the minimum of the average cooling rate from the temperature within the range of 230-330 degreeC immediately after completion | finish of hot rolling to room temperature is not specifically limited, It is preferable to set it as 1 degreeC / hour or more. When the cooling rate during that time is less than 1 ° C./hour, recrystallization occurs almost completely, and it may be difficult to make the recrystallization rate 97% or less in the state cooled to room temperature.
[0042]
(6) The recrystallization rate of the hot rolled plate (hot rolled plate) after cooling to room temperature is set to 97% or less (and therefore corresponds to the partially recrystallized state), and the area ratio of cubically oriented grains is 0. Within the range of 1-50%.
[0043]
The regulation of the recrystallization rate and the area ratio of the cubic orientation grains in the state where the hot rolled up plate is cooled to room temperature is an important point in the method of the present invention, and these values control the low ear rate of the final plate. And it has a great influence on appearance defects. That is, when self-annealing progresses while cooling from room temperature in the range of 230 to 330 ° C. after hot rolling to room temperature, the recrystallization rate exceeds 97% (that is, the state of complete recrystallization or close to it) In the recrystallized state), the effect of enhancing the crystal structure of the cubic orientation cannot be obtained by the subsequent primary cold rolling and intermediate annealing, so that it becomes difficult to control the final plate to a low ear ratio, and at the same time the final The coarsening of the crystal grains of the plate tends to cause appearance defects such as rough skin and flow lines during canning. Therefore, it is necessary to regulate the recrystallization rate in a state cooled to room temperature to 97% or less. Even within this range, the recrystallization rate is preferably regulated to 75% or less. Further, even if the area ratio of the cubic crystal grains is less than 0.1%, it becomes difficult to enhance the cubic crystal structure by the subsequent primary cold rolling and intermediate annealing, and the 45 ° ear of the final plate becomes high. It becomes difficult to achieve a low ear rate. On the other hand, if the area ratio of the cubic orientation crystal grains exceeds 50%, the cubic orientation crystal grains become excessive, and 0 ° -90 ° ears remain in the final plate after the final cold rolling, causing troubles in can manufacturing. .
[0044]
As described above, the hot rolling conditions, that is, the above-described conditions (1) to (5) and the composition of the alloy affect the recrystallization ratio and the cubic crystal grain area ratio after cooling to room temperature. Therefore, the recrystallization rate at room temperature can be controlled to 97% or less and the cubic crystal grain area rate can be controlled to 0.1 to 50% by appropriately adjusting these in relation to each other.
[0045]
In addition, as a hot rolling facility for obtaining the hot rolled sheet as described above, a reversing mill (including a reversing worm mill) is used for each of the rough rolling mill and the finish rolling mill, or rough rolling. In addition, a reversing mill (including reversing / worm mill) also used for finish rolling is used .
[0046]
For the hot-rolled sheet in a partially recrystallized state obtained so as to satisfy the above conditions (1) to (6), primary cold rolling within a range of a rolling rate of 2 to 50% is performed. . In this way, the primary cold rolling is applied to the partially recrystallized hot rolled sheet to give the hot rolled sheet an appropriate strain, thereby promoting the generation and growth of cubic-oriented crystal grains by subsequent annealing. The effect of suppressing the nucleation and growth of crystal grains having orientations other than the cubic orientation can be obtained.
[0047]
Here, when the rolling ratio of the primary cold rolling to the hot-rolled sheet is less than 2%, the effect of accelerating the generation of crystal grains having a cubic orientation due to insufficient strain and the generation and growth of crystal grains having a non-cubic orientation. The suppression effect is insufficient, and in actual industrial production, it is difficult to control a slight reduction amount of less than 2%. On the other hand, if the rolling ratio of the primary cold rolling exceeds 50%, cubic grains and their nuclei are destroyed due to the large amount of strain introduced, and it becomes difficult to enhance the cubic grain structure. The effect of reducing the ear rate of the final plate cannot be obtained, and the final cold rolling rate is relatively reduced, making it difficult to ensure sufficient strength. Therefore, the rolling rate in the primary cold rolling for the hot-rolled sheet is set in the range of 2 to 50%. Here, particularly in the present invention, it is important that the reduction ratio of primary cold rolling can be achieved in a wide range of 2 to 50%, but a low ear ratio can be achieved. Thus, by optimally adjusting the primary cold rolling rate, it becomes possible to improve not only the low ear rate in the final plate but also the balance of the four elements required for the can body material described above. The wide range of the primary cold rolling rate is allowed in this way as described above, so that various conditions of the hot rolling are strictly regulated and it is advantageous for the ear rate control as described above. This is because the recrystallization state and the cubic orientation grain area ratio in the hot rolling process were appropriately controlled.
[0048]
As described above, after the primary cold rolling at a rolling rate of 2 to 50% is performed on the hot-rolled sheet, intermediate annealing is performed by continuous annealing (CAL) or batch annealing. This intermediate annealing is a process necessary to completely recrystallize the material and lower the ear ratio of the final plate after the final cold rolling.
[0049]
When applying the continuous annealing to the intermediate annealing after the primary cold rolling, the continuous annealing is heated to a temperature in the range of 330 to 620 ° C. with an average temperature increase rate in the range of 1 to 100 ° C./second, It is set as the conditions which cool with the average cooling rate within the range of 1-100 degree-C / sec after holding | maintenance without holding | maintenance or 10 minutes or less. Here, if the average heating rate and the average cooling rate are less than 1 ° C./second, the productivity decreases in the continuous annealing (CAL) method, and the average heating rate and the average cooling rate exceed 100 ° C./second. Is disadvantageous for the formation of cubic oriented crystal grains. Further, if the temperature reached by heating is less than 330 ° C., recrystallization hardly occurs. On the other hand, if the temperature exceeds 620 ° C., eutectic melting may occur. Furthermore, holding at 330-620 ° C. for more than 10 minutes inhibits the productivity of continuous annealing.
[0050]
On the other hand, when batch annealing is applied as intermediate annealing after primary cold rolling, heating is performed at an average temperature increase rate of 0.1 ° C./second or less to a temperature in the range of 250 to 500 ° C., and 0 in the temperature range. Hold for 5 hours or more and cool at an average cooling rate of 0.1 ° C./second or less. Here, if the average heating rate and the average cooling rate exceed 0.1 ° C./second, there arises a problem that the whole hot rolled plate coil cannot be uniformly heated or cooled by the batch annealing method. Further, when the heating and holding temperature is less than 250 ° C, it is difficult to completely recrystallize, while at a temperature exceeding 500 ° C, the recrystallization nucleus becomes coarse, and surface defects such as rough skin and flow lines are likely to occur during canning. Become. Further, if the heating and holding time is less than 0.5 hours, it is difficult to completely recrystallize, and it becomes difficult to uniformly heat the entire coil of the hot rolled sheet. The upper limit of the heating and holding time in the case of batch annealing is not particularly defined, but is usually within 24 hours from the viewpoint of economy.
[0051]
Furthermore, in order to realize the low ear ratio of the final plate, the area ratio of the cubic crystal grains is in the range of 1 to 70% in the state after the intermediate annealing by the continuous annealing or the batch annealing as described above. It is necessary to. If the area ratio of the cubic orientation crystal grains is less than 1% in the state after the intermediate annealing, the 45 ° ear of the final plate tends to be high, while if it exceeds 70%, the cubic orientation grains become excessive and 0 ° -90 °. Ears are likely to rise.
[0052]
After performing the intermediate annealing as described above, the final cold rolling is performed at a rolling rate of 50% or more in order to obtain the final thickness and necessary strength. Here, when the rolling ratio of the final cold rolling is less than 50%, the strength increase due to work hardening is small, and it is difficult to obtain the strength necessary for the final plate for the can body material.
[0053]
The plate after the final cold rolling may be subjected to DI forming as it is as the final plate, but the plate after the final cold rolling may be used at a temperature in the range of 80 to 200 ° C. as necessary. A 24-hour final annealing may be performed. This final annealing is aimed at improving the formability by recovering the ductility, but if the temperature is less than 80 ° C, the effect of improving the formability is not sufficiently obtained, while if it exceeds 200 ° C, the strength due to softening is obtained. If the annealing time is less than 0.5 hours, the effect of improving the formability cannot be sufficiently obtained. If the annealing time exceeds 24 hours, the effect of improving the formability is saturated, and the productivity and economy are improved. It only harms sex. Even when the final annealing is not actively performed, the same annealing effect as described above can be obtained by utilizing the processing heat generated by performing the final cold rolling at a high speed.
[0054]
【Example】
Each of the alloy symbols A to E shown in Table 1 was cast into a slab by a DC casting method according to a conventional method. Then, after performing a homogenization treatment, hot rolling (rough rolling-finish rolling) was performed using a reversing mill . Detailed conditions of the homogenization treatment and hot rolling are shown in production numbers 1 to 7 in Tables 2 to 4. Furthermore, after subjecting the hot-rolled sheet after cooling to room temperature to primary cold rolling, continuous annealing or batch annealing was performed as intermediate annealing, and then final cold rolling was performed. In addition, after the last cold rolling, the final annealing was performed except for the case of manufacturing numbers 1, 3, and 6. Detailed conditions after primary cold rolling are shown in production numbers 1 to 7 in Table 5.
[0055]
In addition, while examining the recrystallization rate in the state cooled to room temperature after completion | finish of hot finish rolling, since the area rate of the cubic orientation crystal grain was investigated, the result is shown in Table 3, Table 4. Moreover, since the area ratio of the cubic orientation crystal grain was investigated even in the state after the intermediate annealing, the result is shown in Table 5. Here, the recrystallization rate was obtained from a scan image of an OIM (Orientation Imaging Microscope) orientation analysis microscope. For the measurement of the area ratio of cubic orientation crystal grains, the crystal orientation is specified using the same OIM orientation analysis microscope, and all crystal grains having crystal rotation within a range of ± 15 ° from the center position of the cubic orientation, The nucleus was regarded as a cubic grain and the area ratio was determined.
[0056]
About the aluminum alloy plate for can bodies obtained as described above, the mechanical properties (tensile strength TS, proof stress YS, elongation EL) and ear ratio of the base plate were examined, and paint baking (baking) was assumed. Mechanical properties and DI moldability after heat treatment at 200 ° C. for 20 minutes were examined. Here, the ear ratio of the base plate was examined by conducting a cup deep drawing test under the conditions of a punch diameter of 48 mm, a blank diameter of 93 mm, and a clearance of 30%. The average value of the ear rate was sampled from a total of 25 points at 5 points at equal intervals in the coil longitudinal direction and the width direction, and the difference between the maximum value and the minimum value was regarded as variation. If the average value of the ear rate exceeds 3%, troubles such as running out of cans are likely to occur during can making, and if the variation in ear rate exceeds 3%, the stability of the can manufacturing may be hindered. is there.
[0057]
On the other hand, as an index of DI can moldability,
(1) About the can breakability, the occurrence of broken cans when 10000 cans are continuously subjected to severe ironing,
(2) With regard to the spreadability corresponding to the flange formability, the flange formability after four-stage necking,
(3) For pressure resistance, 4-stage necking, buckling strength of can body after flanging,
(4) Seamability after flanging, seamability with lid,
(5) For appearance defects, flow line-shaped appearance defects along the rolling direction of the can body wall of the DI can and vertical lines generated in the DI direction,
Each of these evaluation items was subjected to a relative evaluation with 5 ranks from 1 to 5. Here, the higher the DI formability evaluation rank value is, the better, and a rank 3 or higher can be evaluated as a pass level.
[0058]

[0059]
[Table 2]

[0060]
[Table 3]

[0061]
[Table 4]

[0062]
[Table 5]

[0063]
[Table 6]

[0064]
In Tables 1 to 6, production numbers 1 to 4 are all manufactured within the component composition range defined in the present invention while satisfying the production process conditions defined in the present invention. As shown in Fig. 6, the ear rate is surely below 3% and a sufficiently low ear rate can be achieved, and the yield strength after baking is 240 MPa or more and has sufficient strength, and DI can moldability Is also clearly superior.
[0065]
On the other hand, in production numbers 5 and 6, the alloy component composition is within the range specified in the present invention, but the manufacturing process conditions are out of the range specified in the present invention.
[0066]
That is, in the process of production number 5, the temperature of the third pass of the finish rolling corresponding to the hot rolling end temperature is as low as 190 ° C. In this case, the area of the cubic-oriented crystal grains in the state cooled to room temperature after the hot rolling is finished. The ratio is less than 0.1%, and the area ratio of the cubic oriented grains after the intermediate annealing is as low as 0.7%. Therefore, the average ear rate is as high as 6.1%, and the can openability is remarkable. It was inferior.
[0067]
In the process of production number 6, the hot finish rolling start temperature is as high as 463 ° C., the recrystallization rate in the fourth pass of finish rolling is as high as 93%, and the finish rolling 5 passes corresponding to the hot rolling finish temperature. This is an example in which the eye temperature is as high as 340 ° C., the material residence time in the fourth pass of finish rolling is as high as 713 seconds, and the primary cold rolling is not performed. In this state, complete recrystallization occurred, and the coil temperature variation in the fourth pass exceeded 70 ° C. In this case, the ear rate was high, and particularly the variation in ear rate was extremely large at 4.3%, and the can tearability and the appearance defect evaluation were inferior.
[0068]
Production number 6 is an example using an alloy E having an Mg amount of 0.46%, which is outside the range specified in the present invention. In this case, the strength after baking is low, the ear rate is high, and DI Formability was also poor.
[0069]
【The invention's effect】
As is apparent from the above-described embodiments, according to the method of the present invention, four elements required as a material for a DI can body, that is, an aluminum alloy having an excellent balance of ear ratio, flange formability, ironability, and strength. A board can be obtained reliably and stably. In particular, in the case of the method of the present invention, by controlling the hot rolling conditions finely, rolling of the first cold rolling out of the two cold rollings with intermediate annealing sandwiched while ensuring a low ear rate. It became possible to adjust the rate in a wide range, so that it was possible to obtain a low ear rate and high strength simultaneously and easily.

Claims

Contains Mg 0.5-2.0% (% by weight, the same shall apply hereinafter), Mn 0.5-2.0%, Fe 0.1-0.7%, Si 0.05-0.5%, and further if necessary After casting an aluminum alloy containing 0.005 to 0.20% Ti alone or in combination with 0.0001 to 0.05% B with the balance being Al and unavoidable impurities, 520 to 630 When performing a homogenization treatment for 1 hour or more at a temperature in the range of ℃, and further performing hot rolling comprising rough rolling and finish rolling using a reversing mill ,
(1) Hot rough rolling is started at a temperature within the range of 350 to 590 ° C.
(2) After completion of hot rough rolling, hot finish rolling is started at a thickness of 50 mm or less and at a temperature within the range of 280 to 450 ° C., and the rolling reduction in each rolling pass of hot finish rolling is 10 to 10. Within 80% range, the material residence time between each rolling pass is within 10 minutes, and the recrystallization rate immediately before the start of the next pass in each rolling pass of hot finish rolling (excluding the final pass) is 90% or less. Control
(3) In each rolling pass of hot finish rolling, the variation in the plate temperature in the coil longitudinal direction and the width direction is controlled within 70 ° C.,
(4) End temperature of hot finish rolling is in the range of 230 to 330 ° C., and finish plate thickness of hot finish rolling is in the range of 1.5 to 4.0 mm.
(5) The average cooling rate from the temperature in the range of 230 to 330 ° C. immediately after completion of hot finish rolling to room temperature is 100 ° C./hr or less,
(6) By the above (1) to (5), the recrystallization rate in the state cooled to room temperature after the hot finish rolling is completed is 97% or less, and the area ratio of the cubic orientation crystal grains is 0.1 to 50. Control within the range of%,
Thereafter, the hot-rolled sheet is subjected to primary cold rolling at a rolling rate within a range of 2 to 50%, and further as an intermediate annealing, with an average temperature increase rate within a range of 1 to 100 ° C./sec. Completely recrystallized by heating to a temperature in the range of ~ 620 ° C without holding or holding for 10 minutes or less, followed by continuous annealing to cool at an average cooling rate in the range of 1-100 ° C / second By controlling the area ratio of the cubic-oriented crystal grains within the range of 1 to 70%, and then performing the final cold rolling at a rolling rate of 50% or more. Manufacturing method.

Mg 0.5-2.0%, Mn 0.5-2.0%, Fe 0.1-0.7%, Si 0.05-0.5%, and Cu 0.05-0.5%, Cr0 0.05-0.3%, Zn 0.05-0.5%, or two or more of them, and if necessary, 0.005-0.20% Ti alone or 0.005%. After casting an aluminum alloy containing 0001 to 0.05% B and the balance being Al and inevitable impurities, homogenization treatment is performed for 1 hour or more at a temperature in the range of 520 to 630 ° C. Furthermore, when performing hot rolling consisting of rough rolling and finish rolling using a reversing mill ,
(1) Hot rough rolling is started at a temperature within the range of 350 to 590 ° C.
(2) After completion of hot rough rolling, hot finish rolling is started at a thickness of 50 mm or less and at a temperature within the range of 280 to 450 ° C., and the rolling reduction in each rolling pass of hot finish rolling is 10 to 10. Within 80% range, the material residence time between each rolling pass is within 10 minutes, and the recrystallization rate immediately before the start of the next pass in each rolling pass of hot finish rolling (excluding the final pass) is 90% or less. Control
(3) In each rolling pass of hot finish rolling, the variation in the plate temperature in the coil longitudinal direction and the width direction is controlled within 70 ° C.,
(4) End temperature of hot finish rolling is in the range of 230 to 330 ° C., and finish plate thickness of hot finish rolling is in the range of 1.5 to 4.0 mm.
(5) The average cooling rate from the temperature in the range of 230 to 330 ° C. immediately after completion of hot finish rolling to room temperature is 100 ° C./hr or less,
(6) By the above (1) to (5), the recrystallization rate in the state cooled to room temperature after the hot finish rolling is completed is 97% or less, and the area ratio of the cubic orientation crystal grains is 0.1 to 50. Control within the range of%,
Thereafter, the hot-rolled sheet is subjected to primary cold rolling at a rolling rate within a range of 2 to 50%, and further as an intermediate annealing, with an average temperature increase rate within a range of 1 to 100 ° C./sec. Completely recrystallized by heating to a temperature in the range of ~ 620 ° C without holding or holding for 10 minutes or less, followed by continuous annealing to cool at an average cooling rate in the range of 1-100 ° C / second By controlling the area ratio of the cubic-oriented crystal grains within the range of 1 to 70%, and then performing the final cold rolling at a rolling rate of 50% or more. Manufacturing method.

Containing Mg 0.5-2.0%, Mn 0.5-2.0%, Fe 0.1-0.7%, Si 0.05-0.5%, and further 0.005-0. After casting an aluminum alloy containing 20% Ti alone or in combination with 0.0001-0.05% B with the balance being Al and unavoidable impurities, at a temperature in the range of 520-630 ° C. When performing a hot rolling consisting of rough rolling and finish rolling using a reversing mill after homogenizing for 1 hour or more,
(1) Hot rough rolling is started at a temperature within the range of 350 to 590 ° C.
(2) After completion of hot rough rolling, hot finish rolling is started at a thickness of 50 mm or less and at a temperature within the range of 280 to 450 ° C., and the rolling reduction in each rolling pass of hot finish rolling is 10 to 10. Within 80% range, the material residence time between each rolling pass is within 10 minutes, and the recrystallization rate immediately before the start of the next pass in each rolling pass of hot finish rolling (excluding the final pass) is 90% or less. Control
(3) In each rolling pass of hot finish rolling, the variation in the plate temperature in the coil longitudinal direction and the width direction is controlled within 70 ° C.,
(4) End temperature of hot finish rolling is in the range of 230 to 330 ° C., and finish plate thickness of hot finish rolling is in the range of 1.5 to 4.0 mm.
(5) The average cooling rate from the temperature in the range of 230 to 330 ° C. immediately after completion of hot finish rolling to room temperature is 100 ° C./hr or less,
(6) By the above (1) to (5), the recrystallization rate in the state cooled to room temperature after the hot finish rolling is completed is 97% or less, and the area ratio of the cubic orientation crystal grains is 0.1 to 50. Control within the range of%,
Thereafter, the hot rolled sheet is subjected to primary cold rolling at a rolling rate within a range of 2 to 50%, and further heated at an average heating rate of 0.1 ° C./second or less as intermediate annealing. Cubic-oriented crystals are obtained by maintaining the temperature in the range of 250 to 500 ° C. for 0.5 hour or more and subjecting the material to complete recrystallization by performing batch annealing for cooling at an average cooling rate of 0.1 ° C./second or less. A method for producing an aluminum alloy plate for a can body, wherein the area ratio of grains is controlled within a range of 1 to 70%, and then final cold rolling is performed at a rolling rate of 50% or more.

Mg 0.5-2.0%, Mn 0.5-2.0%, Fe 0.1-0.7%, Si 0.05-0.5%, and Cu 0.05-0.5%, Cr0 0.05-0.3%, Zn 0.05-0.5%, or two or more of them, and if necessary, 0.005-0.20% Ti alone or 0.005%. After casting an aluminum alloy containing 0001 to 0.05% B and the balance being Al and inevitable impurities, homogenization treatment is performed for 1 hour or more at a temperature in the range of 520 to 630 ° C. Furthermore, when performing hot rolling consisting of rough rolling and finish rolling using a reversing mill ,
(1) Hot rough rolling is started at a temperature within the range of 350 to 590 ° C.
(2) After completion of hot rough rolling, hot finish rolling is started at a thickness of 50 mm or less and at a temperature within the range of 280 to 450 ° C., and the rolling reduction in each rolling pass of hot finish rolling is 10 to 10. Within 80% range, the material residence time between each rolling pass is within 10 minutes, and the recrystallization rate immediately before the start of the next pass in each rolling pass of hot finish rolling (excluding the final pass) is 90% or less. Control
(3) In each rolling pass of hot finish rolling, the variation in the plate temperature in the coil longitudinal direction and the width direction is controlled within 70 ° C.,
(4) End temperature of hot finish rolling is in the range of 230 to 330 ° C., and finish plate thickness of hot finish rolling is in the range of 1.5 to 4.0 mm.
(5) The average cooling rate from the temperature in the range of 230 to 330 ° C. immediately after completion of hot finish rolling to room temperature is 100 ° C./hr or less,
(6) By the above (1) to (5), the recrystallization rate in the state cooled to room temperature after the hot finish rolling is completed is 97% or less, and the area ratio of the cubic orientation crystal grains is 0.1 to 50. Control within the range of%,
Thereafter, the hot rolled sheet is subjected to primary cold rolling at a rolling rate within a range of 2 to 50%, and further heated at an average heating rate of 0.1 ° C./second or less as intermediate annealing. Cubic-oriented crystals are obtained by maintaining the temperature in the range of 250 to 500 ° C. for 0.5 hour or more and subjecting the material to complete recrystallization by performing batch annealing for cooling at an average cooling rate of 0.1 ° C./second or less. A method for producing an aluminum alloy plate for a can body, wherein the area ratio of grains is controlled within a range of 1 to 70%, and then final cold rolling is performed at a rolling rate of 50% or more.

In the manufacturing method of the aluminum alloy plate for can bodies according to any one of claims 1 to 4,
A method for producing an aluminum alloy sheet for a can body, wherein after the final cold rolling is performed, final annealing is further performed at a temperature in the range of 80 to 200 ° C for 0.1 to 24 hours.