JP3644819B2

JP3644819B2 - Method for producing aluminum alloy plate for can body

Info

Publication number: JP3644819B2
Application number: JP07330998A
Authority: JP
Inventors: 岩朱
Original assignee: Furukawa Sky Aluminum Corp
Current assignee: Furukawa Sky Aluminum Corp
Priority date: 1998-03-06
Filing date: 1998-03-06
Publication date: 2005-05-11
Anticipated expiration: 2018-03-06
Also published as: JPH11256291A

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、耳率を如何に制御するかによって、強度、フランジ成形性、耳率のバランスに影響を及ぼすことになるから、耳率制御は缶胴材にとって極めて重要な課題となっている。
【０００７】
しかしながら、前述のような従来の一般的な缶胴材製造方法では、耳率を抑えるにも限界があり、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であった。
【０００８】
そこで低耳率を達成するための缶胴材製造方法が、既に例えば特開平５−３１７９１４号、特開平９−２４９９３２号、特開平９−２６８３５５号等において提案されている。
【０００９】
【発明が解決しようとする課題】
前述の特開平５−３１７９１４号においては、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、製缶時の材料の加工硬化量が大きく、フランジ成形性が悪化する問題がある。
【００１０】
また特開平９−２４９９３２号においては、熱間圧延の最終パスにおける圧延速度、減面率、および熱延終了温度を厳密に規制することによって低耳率を達成する方法が提案されており、この方法は、ある程度は低耳率達成に有効であるが、依然として製造チャンスによる耳率の変動は大きく、確実かつ安定して低耳率を得るには不充分であった。
【００１１】
さらに、特開平９−２６８３５５号においては、熱間仕上圧延にタンデム式圧延機を用いる場合について、熱間仕上圧延条件を細かく規制することにより低耳率を達成する方法が提案されているが、この発明の方法は仕上圧延にタンデム式圧延機を用いた場合に限られるものであって、リバーシングミルを用いる場合については全く考慮されておらず、したがって熱間圧延にリバーシングミルを適用した場合の耳率制御には有効ではない。
【００１２】
以上のように、従来提案されている方法は、缶胴材に対する諸要求を全て充分に満たすことは困難であり、特にリバーシングミルを用いた場合であっても缶胴材として必要な諸特性を充分に満たす材料を得ることは困難であった。
【００１３】
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、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。
【００１４】
またこの発明は、熱間圧延設備としてリバーシングミルを用いた場合に、上述のような缶胴材として優れた性能を有する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目的とする。
【００１５】
【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、熱間圧延工程の諸条件、特に熱間粗圧延中における再結晶を適切に制御すると同時に、再結晶後の仕上圧延の諸条件を厳密に規制することによって、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。
【００１６】
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、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スラブに鋳造した後、そのスラブに対し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スラブを熱間粗圧延およびそれに続く熱間仕上圧延によって熱間圧延するにあたり、
（１）熱間粗圧延開始時のスラブ厚みを２００ｍｍ以上とし、
（２）熱間粗圧延開始温度を４５０〜５８０℃の範囲内とし、
（３）熱間粗圧延中において、粗圧延開始からの圧延率が２５％以上でかつ１５０〜１５ｍｍの範囲内の板厚の段階までの温度を、４００℃以上の温度として、その１５０〜１５ｍｍの範囲内の板厚の段階において板全体に対し体積率で５％以上の再結晶を少なくとも１回以上生じさせ、
（４）熱間仕上圧延の開始温度を２５０〜４００℃の範囲内とし、
（５）熱間仕上圧延における各パスの圧延速度を８０〜８００ｍ／分の範囲内とし、
（６）熱間仕上圧延における各パスの圧延率を２０％以上とし、
（７）さらに熱間仕上圧延における上り温度を２００〜３２０℃の範囲内とし、
（８）かつ熱間仕上圧延における上り板厚を１．０〜７．０ｍｍの範囲内とし、
以上の（１）〜（８）の条件によって得られた熱延板に対して、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時間以上保持するバッチ焼鈍を行なった後、０．１℃／秒以下の平均冷却速度で冷却し、その後さらに６０％以上の圧延率で冷間圧延を行なうことを特徴とするものである。
【００１７】
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、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（粗圧延及び仕上圧延）−バッチ焼鈍−最終冷間圧延のプロセスで製造するものである。
【００１８】
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（粗圧延及び仕上圧延）を請求項１で規定する条件で行ない、その後、熱延板に対して２〜２５％の圧延率で１次冷間圧延を施し、さらに焼鈍として、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分以下の保持の連続焼鈍を施した後、１〜１００℃／秒の範囲内の平均冷却速度で冷却し、その後請求項１の方法と同様に６０％以上の圧延率で最終冷間圧延を行なうものである。
【００１９】
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。
【００２０】
一方請求項５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、さらに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（粗圧延及び仕上圧延）−バッチ焼鈍−最終冷間圧延のプロセスで製造するものである。
【００２１】
また請求項６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（粗圧延及び仕上圧延）−バッチ焼鈍−最終冷間圧延のプロセスで製造するものである。
【００２２】
さらに請求項７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５で規定する合金と同じアルミニウム合金を用い、請求項３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（粗圧延及び仕上圧延）−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。
【００２３】
そしてまた請求項８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６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。
【００２４】
なお、以上の請求項１〜８の方法において、６０％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０．５時間以上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９の発明である。
【００２５】
【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。
【００２６】
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。
【００２７】
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、ゴーリングと呼ば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。この現象は晶出物の大きさ、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。
【００２８】
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。適正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％未満では適正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。
【００２９】
Ｓｉ：
Ｓｉの添加は、Ｍｇ2 Ｓｉ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。
【００３０】
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。
【００３１】
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。
【００３２】
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。
【００３３】
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。
【００３４】
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。
【００３５】
以上の各元素の残部はＡｌと不可避不純物すれば良い。
【００３６】
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。
【００３７】
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。
【００３８】
均質化処理を施したスラブに対しては、熱間圧延を行なう。この熱間圧延は、粗圧延とそれに続く仕上圧延とに区分されるが、この発明の方法の場合、粗圧延にリバーシングミル（可逆式圧延機）を用い、仕上圧延もリバーシングミル（可逆式仕上圧延機；リバーシングウォームミルを含む）を用いる場合を対象としている。
【００３９】
この熱間圧延工程の条件は、この発明の方法の場合極めて重要であり、（１）〜（８）の条件に従って熱間圧延を行なうことが耳率の制御に対して重要である。そこでこれらの（１）〜（８）の条件について詳細に説明する。
【００４０】
（１）熱間粗圧延開始時のスラブ厚みを２００ｍｍ以上とする。
この熱間粗圧延時のスラブ厚みは、後述する（３）項の条件と密接に関係し、板厚１５０ｍｍに達するまでの熱間粗圧延前半の圧下量を確保して、転位を充分に蓄積させるためには、熱間粗圧延開始時のスラブ厚みを２００ｍｍ以上としておく必要があり、好ましくは充分な圧下量を得るために４００ｍｍ以上とする。なおこの熱間粗圧延前半における転位の蓄積に関しては、（３）項において詳細に説明する。
【００４１】
（２）熱間粗圧延開始温度を４５０〜５８０℃の範囲内とする。
熱間粗圧延の開始温度は、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を低くするために必要なキューブ方位の結晶組織（キューブ方位の結晶粒の集合体を以下キューブバンドと称する）の形成に重要な役割を果たしている。熱間粗圧延開始温度が４５０℃未満ではキューブバンドの形成量が不足しやすく、一方５８０℃を越えた高温で熱間粗圧延を開始すれば、キューブバンドの形成は容易となるものの、板の表面品質が低下する。したがって熱間粗圧延開始温度は４５０〜５８０℃の範囲内とする必要がある。
【００４２】
（３）熱間粗圧延中において、粗圧延開始からの圧延率が２５％以上でかつ１５０〜１５ｍｍの範囲内の板厚の段階までの温度を４００℃以上として、その段階において板全体に対し体積率で５％以上の再結晶を少なくとも１回以上生じさせる。
この発明の方法においては、熱間粗圧延中において、熱間粗圧延率が２５％以上でかつ板厚が１５０〜１５ｍｍの範囲内の段階で板全体に対し体積率で５％以上の再結晶を少なくとも１回以上生じさせることが、耳率の制御にとって不可欠である。すなわち、熱間粗圧延率が２５％以上でかつ板厚が１５０〜１５ｍｍの範囲内の段階での再結晶により形成されたキューブバンドは安定であって熱延上り板にも残存し、最終冷間圧延後の最終板の耳率の低減に有効となる。そしてこのように体積率５％以上の再結晶を生じさせるためには、上述の段階での圧延温度を４００℃以上の温度（当然のことながら熱間粗圧延開始温度以下）に制御する必要がある。その段階での圧延温度が４００℃より低くなれば、体積率５％以上の再結晶を生起させることが困難となる。したがってこの発明では、熱間粗圧延中において熱間粗圧延開始からの圧延率が２５％以上であってかつ板厚が１５０〜１５ｍｍの範囲内の段階までの圧延温度を、４００℃以上の温度として、その段階で板全体に対する体積率で５％以上の再結晶を少なくとも１回生起させることとしたのである。
【００４３】
なおここで、熱間粗圧延開始からの熱間粗圧延率が２５％未満の段階では、歪が少なく、板厚１５０〜１５ｍｍの範囲内で体積率５％以上の再結晶を起こさせることが困難である。また１５０ｍｍより厚い段階で再結晶を起こさせること自体は、この発明の効果に対して特に悪影響はないが、１５０ｍｍより厚い段階で再結晶を起こさせて、その後の板厚１５０〜１５ｍｍの範囲内の段階で体積率５％以上の再結晶を生じさせなかった場合には、耳率の制御の効果が充分に得られない。したがって体積率５％以上の再結晶を生じさせる段階は、粗圧延率が２５％以上でかつ板厚が１５０〜１５ｍｍの範囲内の段階とした。なおこの段階で体積率５％以上の再結晶は２回以上生じさせても良いことはもちろんである。またこの段階で生じさせる再結晶は、前述のように板全体に対する体積率で５％以上が必要であるが、より好ましくは、体積率１５％以上の再結晶を生じさせることが望ましい。そしてまた、この段階で体積率５％以上、好ましくは体積率１５％以上の再結晶を生じさせるためには、前述のようにその段階まで圧延温度を４００℃以上に維持する必要があるが、確実に体積率５％以上の再結晶を生じさせるために、必要に応じて熱間粗圧延中途において４００℃以上で１２００秒以内の保持を行なっても良い。
【００４４】
なおまた、前述のように粗圧延率が２５％以上でかつ板厚が１５０〜１５ｍｍの範囲内の段階において体積率５％以上の再結晶を確実に生起させるためには、その板厚の段階までの温度を４００℃以上に維持するばかりでなく、熱間粗圧延開始時のスラブ厚みから板厚１５０ｍｍに達するまでの熱間粗圧延各パスの１パス当り圧下量を１５ｍｍ以上、より最適には４０ｍｍ以上とすることが好ましく、また熱間粗圧延における圧延速度を４０ｍ／分以上、より最適には７０ｍ／分以上とすることが好ましい。
【００４５】
すなわち、熱間粗圧延開始時のスラブ厚み（前述のように２００ｍｍ以上、好ましくは４００ｍｍ以上）から板厚１５０ｍｍまでは、熱間粗圧延のほぼ前半の段階に相当するが、この段階における１パス当りの圧下量は、圧延温度および圧延速度と相俟って材料の回復および再結晶挙動、特に結晶粒サイズ、亜結晶粒サイズに影響を及ぼす。その１パス当りの圧下量が１５ｍｍ未満では転位が蓄積されにくく、結晶粒・亜結晶粒が粗大となる傾向を示し、またキューブバンドの数も少なく、材料の耳率および機械的特性に悪影響を及ぼす。そこで１パス当りの圧下量は１５ｍｍ以上、より最適には４０ｍｍ以上とすることが好ましい。なお各パスの圧下量の上限は特に規制する必要はないが、良好な表面品質を保つため、通常は各パスの１パス当りの圧下量を１００ｍｍ以下とすることが好ましい。
【００４６】
また圧延速度は圧延温度および圧下量と相俟って材料の回復および再結晶挙動、特に結晶粒および亜結晶粒のサイズに強い影響を及ぼす。熱間粗圧延の圧延速度が４０ｍ／分未満では転位が蓄積されにくく、結晶粒、亜結晶粒が粗大となる傾向を示し、キューブバンドの数も少なくなり、材料の耳率および機械的特性に対して悪い影響を及ぼす。また圧延速度が低ければ生産性も低下する。したがって圧延速度は４０ｍ／分以上とすることが好ましく、より好適には７０ｍ／分以上とする。圧延速度の上限は特に規制する必要はないが、良好な表面品質を得るためには、通常は１０００ｍ／分以下が好ましい。
【００４７】
（４）熱間仕上圧延の開始温度を２５０〜４００℃の範囲内とする。
熱間仕上圧延は、適切な転位密度の蓄積を行なうために重要な工程である。すなわち、前述のように熱間粗圧延において板厚が１５０〜１５ｍｍの範囲内の段階で形成されたキューブバンド組織の周辺に、熱間仕上圧延において適切な密度で転位を導入することによって、熱間圧延上りの状態での自己保有熱による自己焼鈍、さらにはその後の焼鈍においてキューブ方位の結晶組織の成長を図ることかでき、ひいては最終冷間圧延後の最終板の耳率を低く規制することに有利となる。ここで、熱間仕上圧延の開始温度が２５０℃未満の場合は、表面品質が低下するとともに、粗大粒子周辺の再結晶核生成数が増加し、その後の再結晶でキューブ方位以外の再結晶粒が多くなり、低耳率制御に不利となる。一方熱間仕上圧延開始温度が４００℃を越える高温では、回復、再結晶が進みやすく、充分な転位を導入することが困難となる。したがって熱間仕上圧延の開始温度は２５０〜４００℃の範囲内とする必要がある。なおこの範囲内でも特に２７０〜３７０℃の範囲内が好ましい。
【００４８】
なお熱間仕上圧延開始温度を２５０〜４００℃、好ましくは２７０〜３７０℃の範囲内に制御するためには、前述のように熱間粗圧延において１５０〜１５ｍｍの板厚の段階で体積率５％以上の再結晶を確保した後、熱間仕上圧延開始までに必要に応じて中間冷却（強制冷却）を行なっても良い。この中間冷却は、例えば熱間圧延機に使用されているクーラントで板を強制冷却したり、そのほか水、油、空気などの冷却媒体を用いて板を強制冷却したりすれば良い。なおこのように中間冷却を行なう場合、１５０〜１５ｍｍの板厚の段階で体積率５％以上の再結晶の確保と中間冷却の実施に要する時間は、生産性の観点から１８００秒以内とすることが好ましい。
【００４９】
（５）熱間仕上圧延における各パスの圧延速度を８０〜８００ｍ／分の範囲内とする。
（６）熱間仕上圧延における各パスの圧延率を２０％以上とする。
熱間仕上圧延の各パスの歪速度は、適切な転位密度の形成および再結晶核生成、特にキューブ方位の再結晶核の生成と成長に大きな影響を及ぼし、適切な密度の転位を導入して低耳率達成に有効なキューブ方位の再結晶核の生成、成長を促進するためには、仕上圧延各パスの歪み速度を０．１〜２５０．０ｓｅｃ^-1とすることが必要であり、より最適には１．０〜９０．０ｓｅｃ^-1の範囲内に制御することが好ましい。熱間仕上圧延各パスの歪み速度は、各パスでの圧延速度と圧延率（圧下量）との組合せによって制御される。したがって熱間仕上圧延各パスの歪み速度を前述のように０．１〜２５０．０ｓｅｃ^-1、好ましくは１．０〜９０．０ｓｅｃ^-1の範囲内に制御するためには、各パスの圧延速度と圧延率とを適切に規制する必要がある。
【００５０】
ここで、熱間仕上圧延各パスの圧延速度が８０ｍ／分未満では、歪み速度が遅く、適切な密度の転位の導入に不利となり、キューブ方位の再結晶核の生成、成長が困難となって低耳率制御が困難となり、一方８００ｍ／分を越えれば、表面品質の低下を招くから、熱間仕上圧延の各パスの圧延速度は８０〜８００ｍ／分の範囲内とする必要がある。
【００５１】
一方熱間仕上圧延各パスの圧延率が２０％以下では、歪み速度が遅くなって、適切な密度の転位の導入が困難となり、キューブ方位の再結晶核の生成、成長が困難となり、低耳率制御が困難となる。したがって熱間仕上圧延各パスの圧延率は２０％以上とした。なお熱間仕上圧延各パスの圧延率の上限は特に定めないが、通常は表面品質の点から、８５％以下とする。
【００５２】
（７）熱間仕上圧延における上り温度を２００〜３２０℃の範囲内とする。
熱間仕上圧延の上り温度が２００℃未満では表面品質が低下し、また第２相粒子周辺での再結晶核生成が増加して、その後の再結晶でキューブ方位以外の再結晶粒が多くなり、低耳率制御に不利となる。一方上り温度が３２０℃を越えれば、最終板の耳率の変動が大きくなり、最終板の耳率を安定して確実に低耳率に制御することが困難となる。
【００５３】
（８）熱間仕上圧延の上り板厚を１．０〜７．０ｍｍの範囲内とする。
仕上圧延の上がり板厚が１．０ｍｍ未満では、焼鈍後の最終的な冷間圧延での圧延率を充分に確保することが困難となり、最終板の強度不足が生じやすい。一方上り板厚が７．０ｍｍを越えれば、焼鈍後の最終的な冷間圧延において圧延率が高くなり過ぎ、耳率が高くなる傾向を示す。
【００５４】
以上で述べたような（１）〜（８）の条件で、リバーシングミルを用いて熱間圧延を終了させた後、その圧延板に対し、バッチ焼鈍により中間焼鈍を施すか、または後述するような軽度の１次冷間圧延を行なってから連続焼鈍による中間焼鈍を施す。この中間焼鈍は、材料を完全に再結晶させて、最終冷間圧延後の板の耳率を低くするために必要な工程である。
【００５５】
ここで、熱延板に対して直ちに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。
【００５６】
ここで、上述の説明では、熱間圧延上がりの熱延板に対してそのままバッチ焼鈍による中間焼鈍を施すこととしているが、中間焼鈍には連続焼鈍を適用することもできる。但し、急速昇温・高温短時間加熱の連続焼鈍では、一般に徐加熱のバッチ焼鈍の場合と比較して、キューブ方位の再結晶粒の形成が少なくなる問題がある。しかしながら、充分な固溶量の確保による高強度化と結晶粒組織の微細化などの観点からは、急速昇温・高温短時間加熱の連続焼鈍法を適用する方が有利となる。そこで連続焼鈍を適用してしかもキューブ方位の再結晶粒の生成に有利な方法を開発すべく種々の検討を重ねた結果、キューブ方位の結晶粒と転位との相互作用が少ないことを利用し、熱延板に対して２〜２５％の比較的小さい冷間圧延率で軽度の１次冷間圧延を行なってから連続焼鈍を施すことにより、キューブ方位の再結晶粒の生成、成長をバッチ焼鈍の場合と同程度に促進させ得ることを見出した。したがって中間焼鈍に連続焼鈍を適用する場合は、熱延板に対して２〜２５％の圧延率の軽度の１次冷間圧延を施してから連続焼鈍を施すこととしたのである。
【００５７】
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、歪み量不足によりキューブ方位の再結晶粒の生成、成長を加速する効果およびキューブ方位以外の再結晶粒の生成、成長を抑制する効果が不充分となり、一方圧延率が２５％を越えれば、導入された多量の歪によりキューブ方位の再結晶粒も壊されてしまうため、キユーブ方位再結晶粒組織を充分に得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る。したがって熱延板に対して１次冷間圧延を施してから連続焼鈍を施す場合の１次冷間圧延における圧延率は２〜２５％の範囲内とした。
【００５８】
前述のように熱延板に対して圧延率２〜２５％の１次冷間圧延を施した後の連続焼鈍は、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、平均冷却速度はキューブ方位の再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℃を越える高温ではキューブ方位の再結晶粒の形成に不利となる。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。
【００５９】
以上のように、バッチ焼鈍もしくは連続焼鈍による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冷間圧延を施す。ここで、最終の冷間圧延率が６０％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。
【００６０】
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、冷間圧延板に必要に応じて８０〜２００℃の範囲内の温度で０．５時間以上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ない。なお焼鈍時間の上限は特に定めないが、生産性、経済性の点からは１０時間以下が望ましい。
【００６１】
【実施例】
表１に示す金属記号Ａ〜Ｆ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、熱間粗圧延および熱間仕上圧延によって熱間圧延を施した。なお熱間圧延設備としては、粗圧延機、仕上圧延機ともにリバーシングミルを用い、熱間粗圧延速度はいずれも５０ｍ／分以上とした。その他の熱間圧延の詳細な条件を表２、表３の製造番号１〜７に示す。熱間仕上圧延後の圧延板に対し、表４中に示す条件でバッチ焼鈍を施すかまたは１次冷間圧延後連続焼鈍を施し、その後最終冷間圧延を行なった。最終冷間圧延後、製造番号５の場合を除いて最終焼鈍を施した。
【００６２】
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を調べた。また元板については、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耳率を調べた。ここで、強度については、塗装焼付（ベーキング）後の耐力として、２７０ＭＰａ以上の値が必要であり、また耳率については、３％を越えれば製缶中のトラブルが発生しやすくなることが知られている。
【００６３】
さらにＤＩ缶成形性評価として、缶切れ性、口拡げ性（フランジ成形性）、シーミング性、および外観欠陥について調べた。ここで、缶切れ性については苛酷なしごき加工を連続１０，０００缶行なったときの缶破断の発生状況を調べ、また口拡げ性については４段ネッキング加工後のフランジ成形性を調べ、さらにシーミング性については４段ネッキング加工後のシーミング加工性を調べ、そしてまた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方向の縦筋の発生状況を調べ、それぞれ◎〜×で相対評価した。これらの結果を表５に示す。
【００６４】
【表１】

【００６５】
【表２】

【００６６】
【表３】

【００６７】
【表４】

【００６８】
【表５】

【００６９】
表１〜表５において、製造番号１〜５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５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２７０ＭＰａ以上で充分な強度を有しており、しかもＤＩ成形性も優れていることが明らかである。
【００７０】
一方製造番号６は、合金の成分組成はこの発明で規定する範囲内であるが、製造プロセス条件がこの発明で規定する範囲から外れたものである。すなわちこの発明の方法の場合、熱間仕上圧延開始温度を４００〜２５０℃の範囲内に制御する必要があるが、製造条件番号６の場合、熱間仕上圧延開始温度が４４７℃とこの発明で規定する温度の上限よりも高く、この場合は最終板の耳率が６．０％と高く、缶切れ性と口拡げ性が劣っていた。
【００７１】
また製造番号７は、Ｍｇ量が０．４８％とこの発明で規定する合金のＭｇ量下限よりも低い合金Ｆ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、缶切れ性に劣っていた。
【００７２】
【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、缶胴の薄肉化に充分耐え得るような高強度を有すると同時に、ＤＩ成形性、特にフランジ成形性に優れ、しかも深絞り耳率が安定して低いアルミニウム合金板を確実に得ることができる。[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. Further, since the balance of strength, flange formability, and ear ratio is affected by how the ear ratio is controlled, the ear ratio control is an extremely important issue for the can body material.
[0007]
However, in the conventional general can body manufacturing method as described above, there is a limit in suppressing the ear rate, and for example, it was difficult to suppress the ear rate to 3% or less at a drawing ratio of 1.9.
[0008]
Therefore, a can body manufacturing method for achieving a low ear ratio has already been proposed in, for example, Japanese Patent Application Laid-Open Nos. 5-317914, 9-249932, and 9-268355.
[0009]
[Problems to be solved by the invention]
In the above-mentioned JP-A-5-317914, a method of performing annealing twice in the middle of cold rolling is proposed, but when annealing is performed twice in the middle of cold rolling in this way, the final cold rolling is performed. Since the rolling rate cannot be increased, there is a problem that the strength is likely to be insufficient, and there is a problem that the work hardening amount of the material at the time of can making is large and the flange formability is deteriorated.
[0010]
Japanese Patent Laid-Open No. 9-249932 proposes a method for achieving a low ear rate by strictly regulating the rolling speed, the area reduction rate, and the hot rolling end temperature in the final pass of hot rolling. Although the method is effective to achieve a low ear ratio to some extent, the fluctuation of the ear ratio due to manufacturing chances is still large, and it is insufficient to obtain a low ear ratio reliably and stably.
[0011]
Furthermore, in JP-A-9-268355, for the case of using a tandem rolling mill for hot finish rolling, a method for achieving a low ear rate by finely regulating the hot finish rolling conditions has been proposed, The method of the present invention is limited to the case where a tandem rolling mill is used for finish rolling, and no consideration is given to the case where a reversing mill is used. Therefore, the reversing mill is applied to hot rolling. It is not effective for controlling the ear rate.
[0012]
As described above, it is difficult for the conventionally proposed methods to fully satisfy all the requirements for the can body material, and various characteristics necessary as a can body material even when a reversing mill is used. It was difficult to obtain a material that sufficiently satisfied the above.
[0013]
The present invention has been made against the background of the above circumstances, and is a material that can sufficiently satisfy various requirements desired as a can body material, that is, excellent in strength and flange formability even when thinned, and deep. The basic object of the present invention is to provide a method capable of producing an aluminum alloy plate for a can body with a reliable and stable low ear ratio of the material in the drawing.
[0014]
The present invention is, when using the re Bashingumiru as a hot rolling equipment, and to provide a method capable of manufacturing an aluminum alloy plate having excellent performance as a can body material, as described above .
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have conducted various experiments and examinations, and as a result, various conditions of the hot rolling process, in particular, recrystallization during hot rough rolling is appropriately controlled and recrystallization is performed. The inventors have found that the above-mentioned problems can be solved by strictly regulating the conditions of the subsequent finish rolling, and have made the present invention.
[0016]
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 containing .05～0.5%, after the aluminum alloy remaining portion is made of Al and unavoidable impurities was cast into a slab, 1 hour or more homogenization at a temperature in the range of five hundred twenty to six hundred and thirty ° C. for that slab When the slab is hot-rolled by hot rough rolling and subsequent hot finish rolling using a reversing mill,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) during rough hot rolling, the temperatures up to the thickness of the steps within the range the rolling rate and the 150~15mm 25% or more from the rough rolling start, and a temperature above 400 ° C., the 150 Causing at least one recrystallization of 5% or more by volume with respect to the whole plate at the stage of the plate thickness within a range of ˜15 mm,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is heated at an average temperature increase rate of 0.1 ° C./second or less to a temperature in the range of 250 to 500 ° C. After performing batch annealing for 5 hours or more, cooling is performed at an average cooling rate of 0.1 ° C./second or less, and then cold rolling is performed at a rolling rate of 60% or more.
[0017]
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 and, using the aluminum alloy remaining portion is made of Al and unavoidable impurities, homogenizing the same conditions and process conditions specified in claim 1 - hot rolling (rough rolling and finish rolling) - batch annealing - final cold It is manufactured by a hot rolling process.
[0018]
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 a material alloy, and homogenization treatment-hot rolling (rough rolling and finish rolling). Is carried out under the conditions specified in claim 1, and then primary cold rolling is applied to the hot-rolled sheet at a rolling rate of 2 to 25%, and further annealing is performed as an average within a range of 1 to 100 ° C / second. After heating to a temperature in the range of 330 to 620 ° C. at a rate of temperature rise and performing continuous annealing without holding or holding for 10 minutes or less, it is cooled at an average cooling rate in the range of 1 to 100 ° C./second, Thereafter, the final cold rolling is performed at a rolling rate of 60% or more in the same manner as in the method of claim 1.
[0019]
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.
[0020]
On the other hand, the manufacturing method of the aluminum alloy plate for can bodies of the invention of claim 5 is as follows: Mg 0.5-2.0%, Mn 0.5-2.0%, Fe 0.1-0.7%, Containing 0.05 to 0.5% Si, further containing 0.005 to 0.20% Ti alone or in combination with 0.0001 to 0.05% B, the balance being Al and inevitable impurities It is manufactured by the process of homogenization treatment-hot rolling (rough rolling and finish rolling) -batch annealing-final cold rolling under the same conditions as the process conditions specified in claim 1. .
[0021]
Moreover, the manufacturing method of the aluminum alloy plate for can bodies of invention of Claim 6 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, 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. It is manufactured by the process of homogenization treatment under the same conditions as those specified in the above-hot rolling (rough rolling and finish rolling)-batch annealing-final cold rolling.
[0022]
Furthermore, the manufacturing method of the aluminum alloy plate for can bodies of the invention of claim 7 uses the same aluminum alloy as the alloy specified in claim 5 as the material alloy, and homogenized under the same conditions as the process conditions specified in claim 3. It is manufactured by a process of processing-hot rolling (rough rolling and finish rolling)-continuous annealing-final cold rolling.
[0023]
And the manufacturing method of the aluminum alloy plate for can bodies of invention of Claim 8 is manufactured by the process prescribed | regulated in Claim 3, using the alloy of the same component composition as the ingredient composition prescribed | regulated in Claim 6 as raw material aluminum alloy. Is.
[0024]
In addition, in the method of the said Claims 1-8 , after performing final cold rolling with the rolling rate of 60% or more, the final annealing which hold | maintains 0.5 hours or more at the temperature within the range of 80-200 degreeC is further carried out. The invention of claim 9 defines this.
[0025]
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.
[0026]
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. Mg also has an effect of multiplying dislocations during 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%.
[0027]
Mn:
Mn is an effective element that contributes to improvement in strength and formability. In particular, Mn is particularly important for the can body material, which is the intended application 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 or seizure called goling may occur. This phenomenon is known to be affected by the size, amount, and type of the crystallized product, 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%.
[0028]
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 amount of Fe is less than 0.1%, it is difficult to obtain a proper compound dispersion state. On the other hand, if the amount of Fe 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%.
[0029]
Si:
The addition of Si contributes to improvement of the strength of the can body material through age hardening by precipitation of Mg2 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%.
[0030]
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%.
[0031]
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.
[0032]
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%.
[0033]
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%.
[0034]
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%.
[0035]
The balance of the above elements may be inevitable impurities with Al.
[0036]
Next, the manufacturing process in this invention is demonstrated with the effect | action.
[0037]
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.
[0038]
Hot rolling is performed on the slab subjected to the homogenization treatment. The hot rolling is divided by the rough rolling and the subsequent finish rolling, in the case of the method of the present invention, using a reversing mill (roll reversible rolling machine) to rough rolling, finish rolling also Ribashingumi Le (reversible This is intended for use of finishing mills (including reversing worm mills ).
[0039]
The conditions of this hot rolling process are extremely important in the case of the method of the present invention, and it is important for the control of the ear rate to perform the hot rolling in accordance with the conditions (1) to (8). Therefore, the conditions (1) to (8) will be described in detail.
[0040]
(1) The slab thickness at the start of hot rough rolling is set to 200 mm or more.
The thickness of the slab during the hot rough rolling is closely related to the condition of the item (3) to be described later, and the amount of rolling in the first half of the hot rough rolling until reaching the plate thickness of 150 mm is secured and the dislocations are sufficiently accumulated. In order to achieve this, the slab thickness at the start of hot rough rolling needs to be 200 mm or more, and preferably 400 mm or more in order to obtain a sufficient reduction amount. The accumulation of dislocations in the first half of hot rough rolling will be described in detail in section (3).
[0041]
(2) The hot rough rolling start temperature is set within a range of 450 to 580 ° C.
The starting temperature of hot rough rolling has a strong influence on the material recovery and recrystallization behavior during hot rolling, and in particular the crystal structure of the cube orientation (cube orientation required to lower the deep drawing ear of the final plate) Of crystal grains (hereinafter referred to as “cube band”) plays an important role. If the hot rough rolling start temperature is less than 450 ° C., the amount of cube band formation tends to be insufficient. On the other hand, if hot rough rolling is started at a high temperature exceeding 580 ° C., cube band formation is facilitated, The surface quality is degraded. Therefore, the hot rough rolling start temperature needs to be in the range of 450 to 580 ° C.
[0042]
(3) during rough hot rolling, and temperatures up to the thickness of the steps within the range the rolling rate and the 150~15mm 25% or more from the rough rolling start and 400 ° C. or higher, the whole plate at that stage In contrast, at least one recrystallization of 5% or more by volume is generated.
In the method of the present invention, during hot rough rolling, recrystallization with a hot rough rolling rate of 25% or more and a plate thickness of 150 to 15 mm in a volume ratio of 5% or more with respect to the whole plate. It is indispensable for the control of the ear rate to generate at least once. That is, the cube band formed by recrystallization at a stage where the hot rough rolling rate is 25% or more and the plate thickness is in the range of 150 to 15 mm is stable and remains on the hot rolled plate, and finally cooled. This is effective in reducing the ear ratio of the final plate after hot rolling. And in order to cause recrystallization with a volume ratio of 5% or more in this way, it is necessary to control the rolling temperature at the above-mentioned stage to a temperature of 400 ° C. or higher (naturally, the hot rough rolling start temperature or lower). is there. If the rolling temperature at that stage is lower than 400 ° C., it will be difficult to cause recrystallization with a volume ratio of 5% or more. Therefore, in this invention, the rolling temperature of the hot rough during rolling there is the rolling rate from a rough hot rolling start 25% or more and a thickness is up to the stage in the range of 150~15mm, 400 ℃ temperatures above and a is the was possible to occur at least once more than 5% of the recrystallized volume fraction for the entire plate at that stage.
[0043]
Here, at the stage where the hot rough rolling rate from the start of hot rough rolling is less than 25%, there is little distortion, and recrystallization with a volume rate of 5% or more within a thickness range of 150 to 15 mm can be caused. Have difficulty. In addition, causing recrystallization at a stage thicker than 150 mm itself has no particular adverse effect on the effect of the present invention, but recrystallization occurs at a stage thicker than 150 mm, and the subsequent plate thickness is within a range of 150 to 15 mm. If recrystallization with a volume ratio of 5% or more is not caused at this stage, the effect of controlling the ear ratio cannot be obtained sufficiently. Therefore, the step of causing recrystallization with a volume ratio of 5% or more was set to a step in which the rough rolling rate was 25% or more and the plate thickness was in the range of 150 to 15 mm. Needless to say, recrystallization with a volume ratio of 5% or more may occur twice or more at this stage. Further, the recrystallization generated at this stage requires a volume ratio of 5% or more with respect to the whole plate as described above, but it is more preferable to cause recrystallization with a volume ratio of 15% or more. Moreover, in order to cause recrystallization at a volume ratio of 5% or more, preferably 15% or more at this stage, it is necessary to maintain the rolling temperature at 400 ° C. or higher until that stage as described above. In order to surely cause recrystallization with a volume ratio of 5% or more, holding may be performed at 400 ° C. or more and 1200 seconds or less during hot rough rolling if necessary.
[0044]
In addition, as described above, in order to surely cause recrystallization with a volume ratio of 5% or more in a stage where the rough rolling rate is 25% or more and the plate thickness is in the range of 150 to 15 mm, the stage of the plate thickness is used. In addition to maintaining the temperature up to 400 ° C. or higher, the reduction amount per pass in each hot rough rolling pass from the slab thickness at the start of hot rough rolling to the plate thickness of 150 mm is more optimally 15 mm or more. Is preferably 40 mm or more, and the rolling speed in the hot rough rolling is preferably 40 m / min or more, and more preferably 70 m / min or more.
[0045]
That is, the slab thickness at the start of hot rough rolling (as described above, 200 mm or more, preferably 400 mm or more) to the plate thickness of 150 mm corresponds to almost the first half of hot rough rolling, but one pass at this stage. The amount of rolling reduction affects the recovery and recrystallization behavior of the material, particularly the grain size and subgrain size, in combination with the rolling temperature and rolling speed. If the rolling reduction per pass is less than 15 mm, dislocations are difficult to accumulate, the crystal grains and sub-crystal grains tend to be coarse, and the number of cube bands is small, which adversely affects the ear ratio and mechanical properties of the material. Effect. Therefore, the amount of reduction per pass is preferably 15 mm or more, and more preferably 40 mm or more. The upper limit of the reduction amount of each pass is not particularly limited, but it is usually preferable that the reduction amount per pass of each pass is 100 mm or less in order to maintain good surface quality.
[0046]
The rolling speed has a strong influence on the recovery and recrystallization behavior of the material, particularly the size of the crystal grains and sub-crystal grains, in combination with the rolling temperature and the amount of reduction. When the rolling speed of the hot rough rolling is less than 40 m / min, dislocations are difficult to accumulate, the crystal grains and sub-crystal grains tend to be coarse, the number of cube bands is reduced, and the ear ratio and mechanical properties of the material are reduced. It has a bad effect on it. Moreover, productivity will fall if rolling speed is low. Therefore, the rolling speed is preferably 40 m / min or more, and more preferably 70 m / min or more. The upper limit of the rolling speed is not particularly limited, but is usually preferably 1000 m / min or less in order to obtain good surface quality.
[0047]
(4) The hot finish rolling start temperature is set within a range of 250 to 400 ° C.
Hot finish rolling is an important process for accumulating an appropriate dislocation density. That is, as described above, by introducing dislocations at an appropriate density in the hot finish rolling around the cube band structure formed in the stage where the plate thickness is in the range of 150 to 15 mm in the hot rough rolling, The self-annealing with self-maintained heat in the state of cold rolling up, and the subsequent crystallographic growth of the cube orientation can be achieved in the subsequent annealing, and as a result, the ear ratio of the final plate after final cold rolling should be regulated low. Is advantageous. Here, when the start temperature of hot finish rolling is less than 250 ° C., the surface quality is lowered and the number of recrystallized nuclei around the coarse particles is increased, and the recrystallized grains other than the cube orientation are subsequently recrystallized. This is disadvantageous for low ear rate control. On the other hand, when the hot finish rolling start temperature is higher than 400 ° C., recovery and recrystallization easily proceed, and it becomes difficult to introduce sufficient dislocations. Therefore, the start temperature of hot finish rolling needs to be in the range of 250 to 400 ° C. Even within this range, a range of 270 to 370 ° C. is particularly preferable.
[0048]
In order to control the hot finish rolling start temperature within the range of 250 to 400 ° C., preferably 270 to 370 ° C., the volume ratio of 5 at the stage of the plate thickness of 150 to 15 mm in the hot rough rolling as described above. After ensuring at least% recrystallization, intermediate cooling (forced cooling) may be performed as necessary before the hot finish rolling is started. For this intermediate cooling, for example, the plate may be forcibly cooled with a coolant used in a hot rolling mill, or the plate may be forcibly cooled using a cooling medium such as water, oil, or air. When intermediate cooling is performed in this way, the time required to ensure recrystallization with a volume ratio of 5% or more and to perform intermediate cooling at a plate thickness of 150 to 15 mm should be within 1800 seconds from the viewpoint of productivity. Is preferred.
[0049]
(5) The rolling speed of each pass in the hot finish rolling is in the range of 80 to 800 m / min.
(6) The rolling rate of each pass in hot finish rolling is 20% or more.
The strain rate of each pass in hot finish rolling has a great influence on the formation of appropriate dislocation density and recrystallization nucleation, especially the formation and growth of recrystallized nuclei in the cube orientation. In order to promote the generation and growth of recrystallized nuclei with a cube orientation effective for achieving a low ear ratio, it is necessary to set the strain rate of each finish rolling pass to 0.1 to 250.0 sec ⁻¹ , Optimally, it is preferable to control within the range of 1.0 to 90.0 sec ⁻¹ . The strain rate of each hot finish rolling pass is controlled by a combination of the rolling rate and rolling rate (reduction amount) in each pass. Therefore 0.1~250.0sec the strain rate of hot finish rolling each path as described above ^-1, preferably in order to control the range of 1.0～90.0Sec ^-1 is rolling in each path It is necessary to appropriately regulate the speed and the rolling rate.
[0050]
Here, if the rolling speed of each hot finish rolling pass is less than 80 m / min, the strain rate is slow, which is disadvantageous for the introduction of dislocations of an appropriate density, and it becomes difficult to generate and grow recrystallized nuclei in the cube orientation. Control of the low ear rate becomes difficult. On the other hand, if it exceeds 800 m / min, the surface quality is deteriorated. Therefore, the rolling speed of each pass of hot finish rolling needs to be in the range of 80 to 800 m / min.
[0051]
On the other hand, when the rolling rate of each hot finish rolling pass is 20% or less, the strain rate becomes slow, it becomes difficult to introduce dislocations with an appropriate density, and it becomes difficult to generate and grow recrystallized nuclei with cube orientation. Rate control becomes difficult. Therefore, the rolling rate of each hot finish rolling pass is set to 20% or more. The upper limit of the rolling rate of each hot finish rolling pass is not particularly defined, but is usually 85% or less from the viewpoint of surface quality.
[0052]
(7) The ascending temperature in the hot finish rolling is set in the range of 200 to 320 ° C.
If the ascending temperature of hot finish rolling is less than 200 ° C, the surface quality deteriorates, and recrystallization nucleation increases around the second phase particles, and subsequent recrystallization increases the number of recrystallized grains other than the cube orientation. It is disadvantageous for low ear rate control. On the other hand, when the rising temperature exceeds 320 ° C., the fluctuation of the ear rate of the final plate increases, and it becomes difficult to stably control the ear rate of the final plate to a low ear rate.
[0053]
(8) The finishing plate thickness of hot finish rolling is set within a range of 1.0 to 7.0 mm.
If the finishing plate thickness of finish rolling is less than 1.0 mm, it becomes difficult to ensure a sufficient rolling rate in the final cold rolling after annealing, and the strength of the final plate is likely to be insufficient. On the other hand, if the ascending plate thickness exceeds 7.0 mm, the rolling rate becomes too high in the final cold rolling after annealing, and the ear rate tends to increase.
[0054]
After finishing the hot rolling using a reversing mill under the conditions (1) to (8) as described above, the rolled sheet is subjected to intermediate annealing by batch annealing or described later. After performing such mild primary cold rolling, intermediate annealing by continuous annealing is performed. This intermediate annealing is a process necessary for completely recrystallizing the material and lowering the ear ratio of the plate after the final cold rolling.
[0055]
Here, when batch annealing is immediately applied to the hot-rolled sheet, it is heated to a temperature within a range of 250 to 500 ° C. at an average temperature rising rate of 0.1 ° C./second or less, and at a temperature within that range, a temperature of 0. 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.
[0056]
Here, in the above description, intermediate annealing by batch annealing is performed as it is on a hot-rolled sheet after hot rolling, but continuous annealing can also be applied to the intermediate annealing. However, continuous annealing with rapid temperature rise and high temperature short time heating generally has a problem that the formation of recrystallized grains with cube orientation is less than that in the case of batch annealing with slow heating. However, from the viewpoint of increasing the strength by securing a sufficient amount of solid solution and refining the grain structure, it is advantageous to apply the continuous annealing method of rapid temperature increase and high temperature short time heating. Therefore, as a result of various studies to apply continuous annealing and develop a method that is advantageous for the formation of recrystallized grains with cube orientation, the fact that there is little interaction between cube-oriented crystal grains and dislocations, Batch annealing is performed to produce and grow recrystallized grains with cube orientation by performing mild primary cold rolling at a relatively low cold rolling rate of 2 to 25% with respect to hot-rolled sheets, followed by continuous annealing. It was found that it can be promoted to the same extent as in the case of. Therefore, when applying the continuous annealing to the intermediate annealing, the continuous annealing is performed after the light primary cold rolling at a rolling rate of 2 to 25% is applied to the hot-rolled sheet.
[0057]
Here, when the rolling ratio of the primary cold rolling on the hot-rolled sheet is less than 2%, generation of recrystallized grains having a cube orientation due to insufficient strain, the effect of accelerating the growth, and generation of recrystallized grains other than the cube orientation The effect of suppressing the growth becomes insufficient. On the other hand, if the rolling rate exceeds 25%, the recrystallized grains in the cube orientation are also broken by the large amount of strain introduced, so that the cube-oriented recrystallized grain structure is sufficiently obtained. This makes it difficult to obtain the ear rate reduction effect of the final plate. Therefore, the rolling rate in primary cold rolling in the case where continuous annealing is performed after performing primary cold rolling on the hot-rolled sheet is set in the range of 2 to 25%.
[0058]
As described above, the continuous annealing after the primary cold rolling at a rolling rate of 2 to 25% is performed on the hot-rolled sheet at 330 to 620 ° C. at an average temperature increase rate within the range of 1 to 100 ° C./second. The temperature is set to a temperature within the range of 1 to 100 ° C./second after holding without holding or holding for 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 recrystallized grains with cube orientation. Further, if the temperature reached by heating is less than 330 ° C., recrystallization hardly occurs, whereas if the temperature exceeds 620 ° C., it is disadvantageous for the formation of recrystallized grains having a cube orientation. Furthermore, holding at 330 to 620 ° C. for more than 10 minutes inhibits the productivity of continuous annealing.
[0059]
As described above, after performing intermediate annealing by batch annealing or continuous annealing, cold rolling is performed in order to obtain a final thickness and necessary strength. Here, when the final cold rolling reduction is less than 60%, 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.
[0060]
The cold-rolled plate may be used as it is as a final plate for DI molding, but the cold-rolled plate may be subjected to final annealing at a temperature in the range of 80 to 200 ° C. for 0.5 hour or longer as necessary. 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 decrease is large and the annealing time is less than 0.5 hours, the effect of improving the formability cannot be obtained sufficiently. The upper limit of the annealing time is not particularly defined, but is preferably 10 hours or less from the viewpoint of productivity and economy.
[0061]
【Example】
Each alloy of metal symbols A to F shown in Table 1 was cast into a slab by a DC casting method according to a conventional method. Then, after performing homogenization treatment, hot rolling was performed by hot rough rolling and hot finish rolling. As the hot rolling equipment, a reversing mill was used for both the rough rolling mill and the finishing mill, and the hot rough rolling speed was 50 m / min or more. Other detailed conditions of hot rolling are shown in Tables 2 and 3 in production numbers 1 to 7. The rolled plate after hot finish rolling was subjected to batch annealing under the conditions shown in Table 4 or continuous annealing after primary cold rolling, and then final cold rolling was performed. After the final cold rolling, final annealing was performed except for the case of production number 5.
[0062]
About the aluminum alloy plate for can bodies obtained as described above, the mechanical properties (tensile strength TS, proof stress YS, elongation EL) and coating baking (baking) of the base plate were assumed at 200 ° C. for 20 minutes. The mechanical properties after the heat treatment were examined. The base plate was subjected to 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%, and the ear rate was examined. Here, with regard to the strength, a value of 270 MPa or more is required as the proof strength after baking (baking), and if the ear rate exceeds 3%, it is known that troubles during can manufacturing are likely to occur. It has been.
[0063]
Further, as a DI can moldability evaluation, can tearability, mouth spreadability (flange moldability), seamability, and appearance defects were examined. Here, regarding can breakability, the state of occurrence of can breakage after continuous 10,000 cans without harsh ironing was investigated, and regarding the spreadability, flange formability after four-stage necking was examined, and seaming was further performed. For seamability, the seaming workability after four-stage necking was investigated, and for appearance defects, the appearance of flow line-like appearance defects along the rolling direction of the can body wall of the DI can and vertical stripes in the DI direction were observed. The relative evaluation was made with 相対 to ×. These results are shown in Table 5.
[0064]
[Table 1]

[0065]
[Table 2]

[0066]
[Table 3]

[0067]
[Table 4]

[0068]
[Table 5]

[0069]
In Tables 1 to 5, production numbers 1 to 5 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. 5, the ear rate is surely below 3% and a sufficiently low ear rate can be achieved, and the strength after baking is 270 MPa or more, and the DI moldability is also good. It is clear that it is excellent.
[0070]
On the other hand, in the production number 6, the alloy component composition is within the range specified in the present invention, but the manufacturing process condition is out of the range defined in the present invention. That is, in the case of the method of the present invention, it is necessary to control the hot finish rolling start temperature within the range of 400 to 250 ° C., but in the case of production condition number 6, the hot finish rolling start temperature is 447 ° C. It was higher than the upper limit of the specified temperature. In this case, the ear rate of the final plate was as high as 6.0%, and the can openability and spreadability were inferior.
[0071]
Production No. 7 is an example using an alloy F having an Mg content of 0.48% which is lower than the lower limit of the Mg content of the alloy defined in the present invention. In this case, the strength after baking is low and the ear rate is also low. It was high and was inferior to cans.
[0072]
【The invention's effect】
As is apparent from the above-described embodiments, according to the method of the present invention, the DI can barrel material has high strength enough to withstand the thinning of the can barrel, and at the same time, DI moldability, particularly flange. It is possible to reliably obtain an aluminum alloy plate that is excellent in formability and has a stable and low deep drawing ratio.

Claims

Mg0.5～2.0% (wt%, hereinafter the same), Mn0.5~2.0%, Fe0.1~0.7%, containing Si0.05～0.5%, the remaining portion of Al After casting an aluminum alloy made of unavoidable impurities into a slab, the slab is homogenized at a temperature in the range of 520 to 630 ° C. for 1 hour or more, and the slab is heated using a reversing mill. In hot rolling by rough rolling and subsequent hot finish rolling,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) during rough hot rolling, the temperatures up to the thickness of the steps within the range the rolling rate and the 150~15mm 25% or more from the rough rolling start, and a temperature above 400 ° C., the 150 Causing at least one recrystallization of 5% or more by volume with respect to the whole plate at the stage of the plate thickness within a range of ˜15 mm,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is heated at an average temperature increase rate of 0.1 ° C./second or less to a temperature in the range of 250 to 500 ° C. For can body characterized by performing batch annealing for 5 hours or more, cooling at an average cooling rate of 0.1 ° C./second or less, and then performing cold rolling at a rolling rate of 60% or more. A method for producing an aluminum alloy plate.

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 .05～0.3%, contain one or two or more of Zn0.05～0.5%, after the aluminum alloy remaining portion is made of Al and unavoidable impurities was cast into a slab, the slab In the case of performing a homogenization treatment for 1 hour or more at a temperature in the range of 520 to 630 ° C., and further hot rolling the slab by hot rough rolling and subsequent hot finish rolling using a reversing mill ,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) during rough hot rolling, the temperatures up to the thickness of the steps within the range the rolling rate and the 150~15mm 25% or more from the rough rolling start, and a temperature above 400 ° C., the 150 Causing at least one recrystallization of 5% or more by volume with respect to the whole plate at the stage of the plate thickness within a range of ˜15 mm,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is heated at an average temperature increase rate of 0.1 ° C./second or less to a temperature in the range of 250 to 500 ° C. For can body characterized by performing batch annealing for 5 hours or more, cooling at an average cooling rate of 0.1 ° C./second or less, and then performing cold rolling at a rolling rate of 60% or more. A method for producing an aluminum alloy plate.

Mg0.5~2.0%, Mn0.5~2.0%, Fe0.1~0.7% , containing Si0.05~0.5%, aluminum remaining portion is made of Al and unavoidable impurities After casting the alloy into a slab, the slab is subjected to a homogenization treatment for 1 hour or more at a temperature in the range of 520 to 630 ° C., and the slab is subjected to hot rough rolling and subsequent hot rolling using a reversing mill. In hot rolling by finish rolling,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) during rough hot rolling, the temperatures up to the thickness of the steps within the range the rolling rate and the 150~15mm 25% or more from the rough rolling start, and a temperature above 400 ° C., the 150 Causing at least one recrystallization of 5% or more by volume with respect to the whole plate at the stage of the plate thickness within a range of ˜15 mm,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is subjected to primary cold rolling at a rolling rate of 2 to 25%, and is further averaged within a range of 1 to 100 ° C./second. After heating to a temperature in the range of 330 to 620 ° C. at a rate of temperature increase and performing continuous annealing without holding or holding for 10 minutes or less, it is cooled at an average cooling rate in the range of 1 to 100 ° C./second. Then, the final cold rolling is further performed at a rolling rate of 60% or more, and the method for producing an aluminum alloy plate for a can body.

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 .05～0.3%, contain one or two or more of Zn0.05～0.5%, after the aluminum alloy remaining portion is made of Al and unavoidable impurities was cast into a slab, the slab In the case of performing a homogenization treatment for 1 hour or more at a temperature in the range of 520 to 630 ° C., and further hot rolling the slab by hot rough rolling and subsequent hot finish rolling using a reversing mill ,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) during rough hot rolling, the temperatures up to the thickness of the steps within the range the rolling rate and the 150~15mm 25% or more from the rough rolling start, and a temperature above 400 ° C., the 150 Causing at least one recrystallization of 5% or more by volume with respect to the whole plate at the stage of the plate thickness within a range of ˜15 mm,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is subjected to primary cold rolling at a rolling rate of 2 to 25%, and is further averaged within a range of 1 to 100 ° C./second. After heating to a temperature in the range of 330 to 620 ° C. at a rate of temperature increase and performing continuous annealing without holding or holding for 10 minutes or less, it is cooled at an average cooling rate in the range of 1 to 100 ° C./second. Then, the final cold rolling is further performed at a rolling rate of 60% or more, and the method for producing an aluminum alloy plate for a can body.

Mg 0.5-2.0%, Mn 0.5-2.0%, Fe 0.1-0.7%, Si 0.05-0.5%, further 0.005-0.20% Ti In an amount of 520 to 630 ° C. with respect to the slab after casting an aluminum alloy containing Al and unavoidable impurities into the slab. In performing a homogenization treatment for 1 hour or more at a temperature, and further hot rolling the slab by hot rough rolling and subsequent hot finish rolling using a reversing mill,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) During hot rough rolling, the rolling rate from the start of rough rolling is 25% or more, and the temperature up to the plate thickness within the range of 150 to 15 mm is set to a temperature of 400 ° C. or more. Less recrystallization of 5% or more by volume with respect to the whole plate at the plate thickness stage within the range of Both at least once,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is heated at an average temperature increase rate of 0.1 ° C./second or less to a temperature in the range of 250 to 500 ° C. For can body characterized by performing batch annealing for 5 hours or more, cooling at an average cooling rate of 0.1 ° C./second or less, and then performing cold rolling at a rolling rate of 60% or more. A method for producing an aluminum alloy plate.

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 one or more of 0.005 to 0.20% Ti alone or 0.0001-0. After casting an aluminum alloy containing 05% B in combination with the balance consisting of Al and inevitable impurities into a slab, the slab is subjected to a homogenization treatment at a temperature in the range of 520 to 630 ° C. for 1 hour or longer. In addition, when the slab is hot-rolled by hot rough rolling and subsequent hot finish rolling using a reversing mill,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) During hot rough rolling, the rolling rate from the start of rough rolling is 25% or more, and the temperature up to the plate thickness within the range of 150 to 15 mm is set to a temperature of 400 ° C. or more. In the stage of the plate thickness within the range of 5% or more, recrystallization of 5% or more by volume ratio with respect to the whole plate is caused at least once,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is heated at an average temperature increase rate of 0.1 ° C./second or less to a temperature in the range of 250 to 500 ° C. For can body characterized by performing batch annealing for 5 hours or more, cooling at an average cooling rate of 0.1 ° C./second or less, and then performing cold rolling at a rolling rate of 60% or more. A method for producing an aluminum alloy plate.

Mg 0.5-2.0%, Mn 0.5-2.0%, Fe 0.1-0.7%, Si 0.05-0.5%, further 0.005-0.20% Ti In an amount of 520 to 630 ° C. with respect to the slab after casting an aluminum alloy containing Al and unavoidable impurities into the slab. In performing a homogenization treatment for 1 hour or more at a temperature, and further hot rolling the slab by hot rough rolling and subsequent hot finish rolling using a reversing mill,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) During hot rough rolling, the rolling rate from the start of rough rolling is 25% or more, and the temperature up to the plate thickness within the range of 150 to 15 mm is set to a temperature of 400 ° C. or more. In the stage of the plate thickness within the range of 5% or more, recrystallization of 5% or more by volume ratio with respect to the whole plate is caused at least once,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is subjected to primary cold rolling at a rolling rate of 2 to 25%, and is further averaged within a range of 1 to 100 ° C./second. After heating to a temperature in the range of 330 to 620 ° C. at a rate of temperature increase and performing continuous annealing without holding or holding for 10 minutes or less, it is cooled at an average cooling rate in the range of 1 to 100 ° C./second. Then, the final cold rolling is further performed at a rolling rate of 60% or more, and the method for producing an aluminum alloy plate for a can body.

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 one or more of 0.005 to 0.20% Ti alone or 0.0001-0. After casting an aluminum alloy containing 05% B in combination with the balance consisting of Al and inevitable impurities into a slab, the slab is subjected to a homogenization treatment at a temperature in the range of 520 to 630 ° C. for 1 hour or longer. In addition, when the slab is hot-rolled by hot rough rolling and subsequent hot finish rolling using a reversing mill,
(1) The slab thickness at the start of hot rough rolling is 200 mm or more,
(2) The hot rough rolling start temperature is in the range of 450 to 580 ° C,
(3) During hot rough rolling, the rolling rate from the start of rough rolling is 25% or more, and the temperature up to the plate thickness within the range of 150 to 15 mm is set to a temperature of 400 ° C. or more. In the stage of the plate thickness within the range of 5% or more, recrystallization of 5% or more by volume ratio with respect to the whole plate is caused at least once,
(4) The hot finish rolling start temperature is in the range of 250 to 400 ° C.
(5) The rolling speed of each pass in hot finish rolling is in the range of 80 to 800 m / min,
(6) The rolling rate of each pass in hot finish rolling is 20% or more ,
(7) Further, the ascending temperature in the hot finish rolling is in the range of 200 to 320 ° C.,
(8) And ascending plate thickness in the hot finish rolling is in the range of 1.0 to 7.0 mm,
The hot-rolled sheet obtained under the above conditions (1) to (8) is subjected to primary cold rolling at a rolling rate of 2 to 25%, and is further averaged within a range of 1 to 100 ° C./second. After heating to a temperature in the range of 330 to 620 ° C. at a rate of temperature increase and performing continuous annealing without holding or holding for 10 minutes or less, it is cooled at an average cooling rate in the range of 1 to 100 ° C./second. Then, the final cold rolling is further performed at a rolling rate of 60% or more, and the method for producing an aluminum alloy plate for a can body.

In the manufacturing method of the aluminum alloy plate for can bodies according to any one of claims 1 to 8 ,
An aluminum alloy sheet for a can body, which is subjected to final annealing at a temperature in the range of 80 to 200 ° C. for 0.5 hour or more after final cold rolling at a rolling rate of 60% or more. Manufacturing method.