JP2004068061A

JP2004068061A - Aluminum alloy plate for can body with excellent stab resistance

Info

Publication number: JP2004068061A
Application number: JP2002227151A
Authority: JP
Inventors: Hiroshi Yokoi; 横井　洋; Eiji Sawa; 澤　英司; Akira Saito; 斎藤　陽; Kiyoshi Fujishiro; 藤代　清; Tokihiko Wada; 和田　時彦
Original assignee: Asahi Breweries Ltd; Sumitomo Light Metal Industries Ltd; Nippon National Seikan Co Ltd
Current assignee: Asahi Breweries Ltd; Sumitomo Light Metal Industries Ltd; Nippon National Seikan Co Ltd
Priority date: 2002-08-05
Filing date: 2002-08-05
Publication date: 2004-03-04

Abstract

【課題】現行の薄肉缶の壁部の肉厚を変えることなく、缶胴体の強度を現行のレベルに維持し、耐突き刺し性に優れた缶胴体を得ることを可能とする缶胴用アルミニウム合金板を提供する。
【解決手段】Ｍｎ：０．８〜１．２％、Ｍｇ：１．０〜１．３％、Ｓｉ：０．３％を越え０．４５％以下、Ｆｅ：０．３〜０．５％を含有し、残部Ａｌおよび不純物からなる組成を有し、熱間圧延後、中間焼鈍を行うことなく冷間圧延し板に、１５０ｍｇ／ｍ^２を越え３００ｍｇ／ｍ^２以下の塗油量でリオイルを施してなるアルミニウム合金板であって、該合金板表面において直径（円相当直径）１〜１０μｍの金属間化合物が３５００〜４５００個／ｍｍ^２の密度、１〜３％の面積率で分布させる。
【選択図】　　　なしAn aluminum alloy for a can body capable of maintaining the strength of the can body at the current level without changing the wall thickness of the current thin can and obtaining a can body excellent in piercing resistance. Provide a board.
SOLUTION: Mn: 0.8 to 1.2%, Mg: 1.0 to 1.3%, Si: more than 0.3% to 0.45% or less, Fe: 0.3 to 0.5% And hot-rolled, and then cold-rolled without intermediate annealing, and re-oiled at a lubrication amount of more than 150 mg / m ² and 300 mg / m ² or less. Wherein an intermetallic compound having a diameter (equivalent circle diameter) of 1 to 10 μm is distributed on the surface of the alloy plate at a density of 3500 to 4500 particles / mm ² and an area ratio of 1 to 3%. .
[Selection diagram] None

Description

【０００１】
【発明の属する技術分野】
本発明は、耐突き刺し性に優れた缶胴用アルミニウム合金板、詳しくは、現行の薄肉缶の重量を変えることなく、缶体強度を維持したままで優れた耐突き刺し性を有する缶胴体に成形することができる耐突き刺し性に優れた缶胴用アルミニウム合金板に関する。
【０００２】
【従来の技術】
アルミニウム合金からなる飲料缶の缶胴体は、板材に塗油を施し、カッピング、ＤＩ加工、トリミング、洗浄、乾燥、外面および内面塗装・焼付け、ネッキング、およびフランジ加工の工程により製造されるが、飲料充填、缶蓋の巻き締め工程、または飲料が充填された缶体を運搬、取り扱う過程で、とくに薄肉の缶胴体に突起物が押し当てられると、缶胴部に凹みが生じ、あるいは突起物の先端が缶胴体を突き刺し貫通して、内容物が漏洩するという問題がある。
【０００３】
このような問題を解決するために、缶胴体の壁部の伸びを大きくする手法が提案されている。例えば、ＪＩＳ　Ａ３１０４合金のＨ１９調質板から缶胴体を成形し、これを２６０〜２８０℃の洗浄乾燥炉中で熱処理することにより、引張強さを低下させるとともに、伸びを増大させることが提案されている（特開昭６１−１９９０５７号公報）が、この手法は缶胴体の壁部の厚さが、例えば０．２１５ｍｍのように厚い場合には効果を有するが、最近のように、例えば約０．１ｍｍと薄肉化された缶胴体の場合には、引張強さが小さく、缶胴体として缶壁強度が不十分となるという難点がある。
【０００４】
ＭｎおよびＭｇを含有する缶胴用アルミニウム合金板をＤＩ加工後、雰囲気温度を２０５〜２４０℃、保持時間を３分以上とし、且つ（雰囲気温度）≧（２２５−保持時間）に特定する熱処理を施し、缶胴体の引張強さを２４０〜２９０ＭＰａのように小さくし、破断伸びを６．２〜８．６％にように増大させることが提案されている（特開平８−１９９２７３号公報）が、この場合も引張強さが小さく、缶胴体としての強度が不足するという問題がある。
【０００５】
【発明が解決しようとする課題】
本発明は、缶胴用アルミニウム合金板における上記従来の問題点を解消するためになされたものであり、その目的は、現行の薄肉缶の壁部の肉厚を変えることなく、すなわち缶胴体の重量を変えることなく、現行金型を適用して缶胴体への成形を行うことができ、缶胴体の強度を現行のレベルに維持し、耐突き刺し性に優れた缶胴体を得ることを可能とする耐突き刺し性に優れた缶胴用アルミニウム合金板を提供することにある。
【０００６】
【課題を解決するための手段】
上記の目的を達成するための本発明の請求項１による耐突き刺し性に優れた缶胴用アルミニウム合金板は、Ｍｎ：０．８〜１．２％、Ｍｇ：１．０〜１．３％、Ｓｉ：０．３％を越え０．４５％以下、Ｆｅ：０．３〜０．５％を含有し、残部Ａｌおよび不純物からなる組成を有し、熱間圧延後、中間焼鈍を行うことなく冷間圧延した厚さ０．２７５〜０．３２５ｍｍのアルミニウム合金冷間圧延板に、１５０ｍｇ／ｍ^２を越え３００ｍｇ／ｍ^２以下の塗油量でリオイルを施してなるアルミニウム合金板であって、該合金板表面において直径（円相当直径）１〜１０μｍの金属間化合物が３５００〜４５００個／ｍｍ^２の密度、１〜３％の面積率で分布していることを特徴とし、ＤＩ加工、塗装を含む缶胴成形工程で、外面および内面塗装を含む厚さが０．１１０〜０．１３０ｍｍの壁部をそなえた缶胴体に成形した場合、該壁部の缶軸方向において、伸びが３％以上６％未満、引張強さが２９０ＭＰａを越え３３０ＭＰａ以下の特性を有する。
【０００７】
また、請求項２による耐突き刺し性に優れた缶胴用アルミニウム合金板は、請求項１において、ＤＩ加工、塗装を含む缶胴成形工程で、外面および内面塗装を含む厚さが０．１１０〜０．１３０ｍｍの壁部をそなえた缶胴体に成形した場合、缶胴体の内部から２００ｋＰａの内圧を負荷した状態で、前記壁部に、先端半径が０．５ｍｍの突起物を５０ｍｍ／分の速度で突き刺し貫通させた場合の最大荷重が４．５〜５．５ｋｇｆの特性を有するものである。
【０００８】
【発明の実施の形態】
本発明の缶胴用アルミニウム合金における合金成分の意義および限定理由について説明する。
Ｍｎ：Ｍｎは、成形される缶胴体の強度を向上するよう機能するもので、好ましい含有量は０．８〜１．２％の範囲であり、この範囲のＭｎを含有させることにより適切な金属間化合物の分布密度および面積率を得ることができる。０．８％未満では、塗装後の缶胴体に２９０ＭＰａ以上の十分な引張強さを付与することが困難であり、１．２％を越えて含有されると、缶胴体への成形が難しくなり、仮に成形できたとしても塗装後に強度が高くなり過ぎ、耐突き刺し性が低下する。
【０００９】
Ｍｇ：Ｍｎとともに成形される缶胴体の強度を高めるよう機能するもので、好ましい含有範囲は１．０〜１．３％である。１．０％未満では、塗装後の缶胴体に２９０ＭＰａ以上の十分な引張強さを付与することが困難であり、１．３％を越えて含有されると、缶胴体への成形が難しくなり、仮に成形できたとしても塗装後に強度が高くなり過ぎ、耐突き刺し性が低下する。
【００１０】
Ｓｉ：Ｓｉは、成形される缶胴体の伸びを高めるよう機能するもので、好ましい含有量は０．３％を越え０．４５％以下の範囲であり、この範囲のＳｉを含有させることにより、適切な金属間化合物の分布密度および面積率を得ることができる。０．３％以下では、塗装後の缶胴体に３％以上の十分な伸びを与えることが難しく、０．４５％を越えると、塗装後の缶胴体の伸びが大きくなり過ぎ、引張強さが低下するため、缶胴体として十分な強度を与えることが難しくなる。
【００１１】
Ｆｅ：Ｆｅも成形される缶胴体の強度を向上させる。好ましい含有量は０．３〜０．５％の範囲であり、この範囲のＦｅを含有させることにより適切な金属間化合物の分布密度および面積率を得ることができる。０．３％未満では、塗装後の缶胴体に２９０ＭＰａ以上の十分な引張強さを付与することが困難であり、０．５％を越えて含有されると、缶胴体への成形が難しくなり、仮に成形できたとしても塗装後に強度が高くなり過ぎ、耐突き刺し性が低下する。
【００１２】
なお、本発明のアルミニウム合金板においては、不純物として、０．２５％以下のＣｕ、０．２５％以下のＺｎ、０．２０％以下のＣｒ、結晶粒微細化材として通常添加される０．２０％以下のＴｉ、０．１０％以下のＢが含有されていても、本発明の効果に影響することはない。
【００１３】
本発明の缶胴用アルミニウム合金板において、所望の特性を得るためには、合金成分のＭｎ、Ｓｉ、Ｆｅなどが関与する金属間化合物の分布密度および面積率を特定することが重要であり、板表面において直径（円相当直径）１〜１０μｍの金属間化合物を３５００〜４５００個／ｍｍ^２の密度、１〜３％の面積率で分布させることが好ましい。金属間化合物の分布密度および面積率をこの範囲に特定することによって、缶胴成形工程において、カッピングおよびＤＩ加工での缶胴体部の加工組織の集積を緩和し、その後の熱処理、すなわち洗浄後の乾燥工程、缶胴体の内外面塗装後の焼付け工程における熱処理において、引張強さと伸びのバランスに優れ、改善された耐突き刺し性をそなえた缶胴体を得ることができる。
【００１４】
直径１〜１０μｍの金属間化合物が３５００個／ｍｍ^２未満の場合、または金属間化合物がマトリックス全体に占める面積率が１％未満の場合には、缶胴体部の加工組織の集積が強固となり、その後の熱処理において、必要な引張強さと伸びを有し、耐突き刺し性をそなえた缶胴体が得難くなる。直径１〜１０μｍの金属間化合物が４５００個／ｍｍ^２を越える場合、または金属間化合物がマトリックス全体に占める面積率が３％を越える場合には、缶胴成形工程の熱処理において、軟化が進行し易くなるため十分な缶胴体強度を得ることが困難となる。
【００１５】
本発明の缶胴用アルミニウム合金板は、最終的に０．２７５〜０．３２５ｍｍの厚さに冷間圧延された冷間圧延板として供給され、この範囲の厚さと前記成分組成との組合わせにより、現行の薄肉缶の壁部の肉厚を変えることなく、すなわち缶胴体の重量を変えることなく、現行金型を適用して缶胴体への成形を行うことができ、缶胴体の強度を現行のレベルに維持し、耐突き刺し性に優れた缶胴体を得ることができる。
【００１６】
本発明による缶胴用アルミニウム合金板は、前記組成を有するアルミニウム合金の鋳塊を、常法に従って均質化処理後、熱間圧延、冷間圧延を経て製造されるが、前記本発明の金属間化合物の分布密度および面積率を得るためには、通常、熱間圧延工程と冷間圧延工程との間で行われる中間焼鈍を実施しないことが望ましい。バッチ炉による中間焼鈍を行うと、直径１〜１０μｍの金属間化合物の分布が変動し、前記特定の分布密度が得難くなる。一方、連続焼鈍炉による急速加熱、急速冷却での中間焼鈍を行うと、缶胴成形工程における熱処理で焼付硬化するために缶壁部の伸びが得難くなる。
【００１７】
仕上げ冷間圧延によって厚さ０．２７５〜０．３２５ｍｍに加工された本発明の缶胴用アルミニウム合金板は、１５０ｍｇ／ｍ^２を越え３００ｍｇ／ｍ^２以下の塗油量でリオイルを施し、カッピング、ＤＩ加工、トリミング、洗浄、乾燥、内面塗装・焼付け、外面塗装・焼付け、ネッキングおよびフランジングの缶胴成形工程で、外面および内面塗装を含む厚さが０．１１０〜０．１３０ｍｍの壁部をそなえた缶胴体に成形した場合、該壁部の缶軸方向において、伸びが３％以上６％未満、引張強さが２９０ＭＰａを越え３３０ＭＰａ以下の特性を有する。
【００１８】
カッピング、ＤＩ成形に先立って行われるリオイルは、アルミニウム合金板メーカーにおいて、板表面に予め付着されている圧延油などを除去した後の塗油であり、ＤＩ成形時の潤滑性を付与する以外に、搬送時などでの傷付きを防止すると重要な役割がある。成形される板に大きな傷がある場合には、成形時に缶切れが生じ、傷が小さい場合には、例え成形できたとしても板の傷部が局所的に薄くなってしまうため、内容物充填時に内圧がかかった段階でピンホールとなり、内容物が漏れたり、耐突き刺し性を低下させる。本発明の缶胴用アルミニウム合金板において、このような問題を解決するための塗油量は１５０ｍｇ／ｍ^２を越え３００ｍｇ／ｍ^２以下の範囲である。
【００１９】
缶胴体への成形は、外面塗膜および内面塗膜を含む缶胴体壁部の厚さが０．１１０〜０．１３０ｍｍとなるよう行われる。０．１１０ｍｍ未満では耐突き刺し性が劣る。塗装前の缶胴体壁部の厚さは略０．１００〜０．１１０ｍｍである。
【００２０】
缶胴体の壁部の引張強さと伸びの測定は、厚さ０．１１０〜０．１３０ｍｍの壁部が中央になるように引張試験片を採取し、引張チャック間の平行部の幅を８ｍｍ、標点間距離を１０ｍｍとして、引張強さと伸びをＪＩＳ　Ｚ２２４１に準じて求めた。引張試験片は、内外面塗膜を脱膜して試験を行い、４つの試験片による測定（ｎ＝４）の平均値を求めた。
【００２１】
引張強さが２９０ＭＰａを越え３３０ＭＰａ以下、伸びが３％以上、６％未満の場合を合格とする。この範囲の引張強さと伸びのバランスで、十分な強度をそなえ、耐突き刺し性に優れた缶胴体となる。また、缶底耐圧、すなわち内圧を負荷した場合、缶底がバックリングする限界圧力は、６００ｋＰａ以上でなければならない。
【００２２】
さらに、本発明の缶胴用アルミニウム合金板は、１５０ｍｇ／ｍ^２を越え３００ｍｇ／ｍ^２以下の塗油量で塗油を施し、ＤＩ加工、塗装を含む缶胴成形工程で、外面塗膜および内面塗膜を含む厚さが０．１１０〜０．１３０ｍｍの壁部をそなえた缶胴体に成形した場合、最大荷重が４．５ｋｇｆ以上５．５ｋｇｆ以下の優れた突き刺し強度を有する。
【００２３】
突き刺し強度の測定は、成形した缶胴体の内部から２００ｋＰａの内圧を負荷した状態で、前記外面塗膜および内面塗膜を含む厚さが０．１１０〜０．１３０ｍｍの壁部に、先端半径が０．５ｍｍ、直径１ｍｍの突起物を５０ｍｍ／分の速度で突き刺し貫通させた場合の最大荷重を、１０回の測定（ｎ＝１０）の平均値として求めた。
【００２４】
【実施例】
以下、本発明の実施例を比較例と対比して説明する。これらの実施例は本発明の一実施態様を示すものであり、本発明はこれに限定されるものではない。
【００２５】
実施例１
半連続鋳造により得られた、表１に示す組成を有する缶胴用アルミニウム合金の鋳塊を、常法に従って均質化処理、熱間圧延後、中間焼鈍を行うことなく、冷間圧延を行い、厚さ０．３ｍｍの冷間圧延板とした。
【００２６】
得られた冷間圧延板を試験材として、金属間化合物の分布密度およびその面積率を測定した。測定結果を表１に示す。測定は、アルミニウム合金板の表面を脱脂洗浄後、ＳＥＭ（走査型電子顕微鏡）の組成像で該板表面を撮影し、金属間化合物の粒径分布を画像解析装置（（株）ニレコ製ルーゼクス５００）を用いて測定する。この場合、金属間化合物の直径は円相当直径、すなわち写真における金属間化合物の面積と同じ面積を有する円の直径として測定した。
【００２７】
つぎに、試験材に表２に示す塗油量で塗油した後、通常の前記缶胴成形工程に従って、表２に示す壁厚を有する缶胴体に成形し、前記の測定方法に従って、缶胴体の壁部の引張強さ、伸び、突き刺し強度を求め、缶底耐圧も測定した。結果を表２に示す。
【００２８】
表２にみられるように、本発明に従う試験材から成形された缶胴体はいずれも、壁部の引張強さが２９０ＭＰａを越え３３０ＭＰａ以下、伸びが３％以上６％未満で、缶底耐圧が６００ｋＰａ以上で、缶胴体として十分な強度をそなえ、突き刺し強度も４．５ｋｇｆ以上の優れた値を示した。
【００２９】
【表１】

【００３０】
【表２】

【００３１】
比較例１
半連続鋳造により得られた、表３に示す組成を有する缶胴用アルミニウム合金の鋳塊を、常法に従って均質化処理、熱間圧延後、合金Ｍ以外は中間焼鈍を行うことなく、冷間圧延を行い、厚さ０．３ｍｍの冷間圧延板とした。
【００３２】
得られた冷間圧延板を試験材として、金属間化合物の分布密度およびその面積率を実施例１と同じ方法で測定した。測定結果を表３に示す。表３において、本発明の条件を外れたものには下線を付した。
【００３３】
つぎに、試験材に表４に示す塗油量で塗油した後、通常の前記缶胴成形工程に従って、表４に示す壁厚を有する缶胴体に成形し、前記の測定方法に従って、缶胴体の壁部の引張強さ、伸び、突き刺し強度を求め、缶底耐圧も測定した。結果を表４に示す。
【００３４】
【表３】

《表注》アルミニウム合金板Ｍは熱間圧延後に中間焼鈍を行った
【００３５】
【表４】

【００３６】
表４に示すように、試験材Ｎｏ．１１はＳｉ量が少ないため、缶胴体として強度が大きくなり過ぎ耐突き刺し性が劣る。試験材Ｎｏ．１２はＳｉ量、Ｍｇ量がが少ないため、伸びが得られず耐突き刺し性が劣る。試験材Ｎｏ．１３はＳｉ量が多いため、伸びが高くなり過ぎ強度低下が生じる。試験材Ｎｏ．１４はＭｇ量が少ないため、また試験材Ｎｏ．１５はＭｎ量が少ないため、いずれも缶胴体として十分な強度が得られない。試験材Ｎｏ．１６は金属間化合物の分布が多いため、缶胴体の成形工程の熱処理で軟化が進み缶胴体として十分な強度が得られない。試験材Ｎｏ．１７は熱間圧延後に中間焼鈍を行ったもので、金属間化合物の分布が少なくなり耐突き刺し性が劣る。
【００３７】
【発明の効果】
本発明によれば、現行の薄肉缶の壁部の肉厚を変えることなく、すなわち缶胴体の重量を変えることなしに、現行金型を適用して缶胴体への成形を行うことができ、缶胴体の強度を現行のレベルに維持し、耐突き刺し性に優れた缶胴体を得ることを可能とする耐突き刺し性に優れた缶胴用アルミニウム合金板が提供される。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an aluminum alloy plate for a can body having excellent stab resistance, more specifically, forming a can body having excellent stab resistance while maintaining the strength of the can without changing the weight of the existing thin-walled can. The present invention relates to an aluminum alloy plate for a can body having excellent stab resistance.
[0002]
[Prior art]
The body of a beverage can made of an aluminum alloy is manufactured by applying oil to the plate material, cupping, DI processing, trimming, washing, drying, outer and inner surface coating and baking, necking, and flange processing. When a projection is pressed against a thin-walled can body during the filling, can lid winding process, or the process of transporting and handling the can body filled with beverage, a dent may occur in the can body, or There is a problem that the tip pierces and penetrates the can body and the contents leak.
[0003]
In order to solve such a problem, a method of increasing the elongation of the wall of the can body has been proposed. For example, it has been proposed to form a can body from a H19 tempered plate of JIS A3104 alloy and heat-treat it in a washing and drying furnace at 260 to 280 ° C. to reduce tensile strength and increase elongation. (Japanese Patent Application Laid-Open No. 61-199057), this method is effective when the thickness of the wall of the can body is as thick as, for example, 0.215 mm. In the case of a can body thinned to 0.1 mm, there is a drawback that the tensile strength is small and the can wall strength of the can body becomes insufficient.
[0004]
After the DI processing of the aluminum alloy plate for the can body containing Mn and Mg, the heat treatment is performed by setting the atmosphere temperature to 205 to 240 ° C., the holding time to 3 minutes or more, and specifying (atmospheric temperature) ≧ (225-holding time). It has been proposed to reduce the tensile strength of the can body to 240 to 290 MPa and increase the elongation at break to 6.2 to 8.6% (Japanese Patent Laid-Open No. 8-199273). However, also in this case, there is a problem that the tensile strength is small and the strength of the can body is insufficient.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems in an aluminum alloy plate for a can body, and an object thereof is to change the thickness of a wall portion of a current thin can without changing the thickness of a can body. It is possible to apply the current mold to the can body without changing the weight, maintain the strength of the can body at the current level, and obtain a can body with excellent stab resistance. An object of the present invention is to provide an aluminum alloy plate for a can body having excellent stab resistance.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the aluminum alloy plate for a can body having excellent stab resistance according to claim 1 of the present invention has Mn: 0.8 to 1.2% and Mg: 1.0 to 1.3%. , Si: more than 0.3% and 0.45% or less, Fe: 0.3 to 0.5%, having a composition consisting of the balance of Al and impurities, and performing intermediate annealing after hot rolling. An aluminum alloy sheet obtained by applying a re-oiling method to a cold-rolled aluminum alloy sheet having a thickness of 0.275 to 0.325 mm, which is cold-rolled, with a coating amount of more than 150 mg / m ² and 300 mg / m ² or less. The metal plate is characterized in that intermetallic compounds having a diameter (equivalent diameter of a circle) of 1 to 10 μm are distributed at a density of 3500 to 4500 particles / mm ² and an area ratio of 1 to 3% on the surface of the alloy plate. In the can body forming process including painting, the outer and inner surfaces are painted. When formed into a can body having a wall with a thickness of 0.110 to 0.130 mm, the wall has an elongation of 3% or more and less than 6% and a tensile strength exceeding 290 MPa and 330 MPa in the direction of the can axis. It has the following characteristics.
[0007]
The aluminum alloy sheet for a can body having excellent stab resistance according to the second aspect is the can body forming step including the DI processing and the coating according to the first aspect, wherein the thickness including the outer surface and the inner surface coating is 0.110 to 0.110. When molded into a can body having a wall of 0.130 mm, a projection having a tip radius of 0.5 mm is applied to the wall at a speed of 50 mm / min while an internal pressure of 200 kPa is applied from the inside of the can body. And has a maximum load of 4.5 to 5.5 kgf when penetrated.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The significance of the alloy components in the aluminum alloy for a can body of the present invention and the reasons for limitation will be described.
Mn: Mn functions to improve the strength of the can body to be formed, and the preferred content is in the range of 0.8 to 1.2%. The distribution density and area ratio of the inter-compound can be obtained. If it is less than 0.8%, it is difficult to impart a sufficient tensile strength of 290 MPa or more to the can body after coating, and if it exceeds 1.2%, it becomes difficult to form the can body. Even if it can be formed, the strength after coating becomes too high, and the piercing resistance is reduced.
[0009]
It functions to increase the strength of the can body formed together with Mg: Mn, and the preferred content range is 1.0 to 1.3%. If it is less than 1.0%, it is difficult to impart a sufficient tensile strength of 290 MPa or more to the can body after coating, and if it exceeds 1.3%, it becomes difficult to form the can body. Even if it can be formed, the strength after coating becomes too high, and the piercing resistance is reduced.
[0010]
Si: Si functions to increase the elongation of the can body to be formed, and the preferable content is more than 0.3% and not more than 0.45%. By including Si in this range, An appropriate distribution density and area ratio of the intermetallic compound can be obtained. If it is less than 0.3%, it is difficult to give a sufficient elongation of 3% or more to the can body after painting. If it exceeds 0.45%, the elongation of the can body after painting becomes too large, and the tensile strength becomes insufficient. Therefore, it becomes difficult to provide sufficient strength as a can body.
[0011]
Fe: Fe also improves the strength of the molded can body. The preferred content is in the range of 0.3 to 0.5%, and by including Fe in this range, an appropriate distribution density and area ratio of the intermetallic compound can be obtained. If it is less than 0.3%, it is difficult to impart a sufficient tensile strength of 290 MPa or more to the can body after coating, and if it exceeds 0.5%, it becomes difficult to form the can body. Even if it can be formed, the strength after coating becomes too high, and the piercing resistance is reduced.
[0012]
In the aluminum alloy sheet of the present invention, as impurities, Cu of 0.25% or less, Zn of 0.25% or less, Cr of 0.20% or less, and 0. Even if it contains 20% or less of Ti and 0.10% or less of B, the effect of the present invention is not affected.
[0013]
In the aluminum alloy sheet for a can body of the present invention, in order to obtain desired properties, it is important to specify the distribution density and area ratio of the intermetallic compound involving Mn, Si, Fe, and the like of the alloy component, It is preferable to distribute intermetallic compounds having a diameter (equivalent circle diameter) of 1 to 10 μm on the plate surface at a density of 3500 to 4500 particles / mm ² and an area ratio of 1 to 3%. By specifying the distribution density and the area ratio of the intermetallic compound in this range, in the can body forming step, the accumulation of the working structure of the can body in cupping and DI processing is relaxed, and the subsequent heat treatment, that is, after cleaning, In the drying step and the heat treatment in the baking step after coating the inner and outer surfaces of the can body, a can body having an excellent balance between tensile strength and elongation and having improved piercing resistance can be obtained.
[0014]
When the number of intermetallic compounds having a diameter of 1 to 10 μm is less than 3500 / mm ² , or when the area ratio of the intermetallic compounds to the entire matrix is less than 1%, the accumulation of the processed structure of the can body becomes strong, In the subsequent heat treatment, it becomes difficult to obtain a can body having necessary tensile strength and elongation and having piercing resistance. When the number of intermetallic compounds having a diameter of 1 to 10 μm exceeds 4500 particles / mm ² , or when the area ratio of the intermetallic compounds to the entire matrix exceeds 3%, softening proceeds in the heat treatment in the can body forming step. Therefore, it becomes difficult to obtain sufficient strength of the can body.
[0015]
The aluminum alloy sheet for a can body of the present invention is finally supplied as a cold-rolled sheet cold-rolled to a thickness of 0.275 to 0.325 mm, and a combination of the thickness in this range and the above component composition. Therefore, without changing the wall thickness of the wall of the current thin can, that is, without changing the weight of the can body, the current mold can be applied to form the can body, and the strength of the can body can be increased. It is possible to obtain a can body which is maintained at the current level and has excellent stab resistance.
[0016]
The aluminum alloy sheet for a can body according to the present invention is manufactured by subjecting an ingot of an aluminum alloy having the above composition to homogenization treatment according to a conventional method, followed by hot rolling and cold rolling. In order to obtain the distribution density and the area ratio of the compound, it is usually desirable not to carry out the intermediate annealing performed between the hot rolling step and the cold rolling step. When the intermediate annealing is performed in a batch furnace, the distribution of the intermetallic compound having a diameter of 1 to 10 μm fluctuates, and it becomes difficult to obtain the specific distribution density. On the other hand, when rapid heating in a continuous annealing furnace and intermediate annealing by rapid cooling are performed, baking and hardening are performed by heat treatment in a can body forming step, so that elongation of the can wall becomes difficult to obtain.
[0017]
The aluminum alloy sheet for a can body of the present invention processed to a thickness of 0.275 to 0.325 mm by finish cold rolling is subjected to re-oiling at an oiling amount of more than 150 mg / m ² and 300 mg / m ² or less, and cupping is performed. In the can body forming process of DI processing, trimming, washing, drying, inner surface coating and baking, outer surface coating and baking, necking and flanging, the wall portion including the outer and inner surfaces is 0.110 to 0.130 mm thick When formed into a can body having the following characteristics, the wall portion has characteristics of elongation of 3% or more and less than 6% and tensile strength of more than 290 MPa and not more than 330 MPa in the direction of the can axis.
[0018]
Re-oiling performed prior to cupping and DI molding is a coating oil after removing rolling oil and the like previously attached to the plate surface at an aluminum alloy plate maker, in addition to providing lubrication during DI molding. There is an important role in preventing damage during transportation. If the plate to be molded has large scratches, the can will break during molding, and if the scratches are small, even if it can be molded, the scratches on the plate will be thin locally, so the contents are filled. At times when internal pressure is applied, a pinhole is formed, and the contents leak or the piercing resistance is reduced. In the aluminum alloy plate for a can body of the present invention, the amount of oil applied to solve such a problem is in the range of more than 150 mg / m ² and 300 mg / m ² or less.
[0019]
The molding into the can body is performed so that the thickness of the can body wall portion including the outer surface coating film and the inner surface coating film is 0.110 to 0.130 mm. If it is less than 0.110 mm, the piercing resistance is poor. The thickness of the can body wall before painting is approximately 0.100 to 0.110 mm.
[0020]
For the measurement of the tensile strength and elongation of the wall of the can body, a tensile test piece was collected so that the wall having a thickness of 0.110 to 0.130 mm was at the center, and the width of the parallel portion between the tensile chucks was 8 mm. The tensile strength and elongation were determined according to JIS Z2241 with the distance between the gauge points being 10 mm. The tensile test pieces were tested by removing the inner and outer coating films, and the average value of measurements (n = 4) of the four test pieces was obtained.
[0021]
A case where the tensile strength is more than 290 MPa and less than or equal to 330 MPa, the elongation is 3% or more and less than 6% is regarded as acceptable. With the balance between tensile strength and elongation in this range, a can body having sufficient strength and excellent piercing resistance can be obtained. Further, when the can bottom pressure is applied, that is, when the internal pressure is applied, the limit pressure at which the can bottom buckles must be 600 kPa or more.
[0022]
Furthermore, the aluminum alloy sheet for a can body of the present invention is applied with an oil amount of more than 150 mg / m ² and 300 mg / m ² or less, and is subjected to DI processing and painting in a can body forming step including coating, so that the outer surface coating and When molded into a can body having a wall portion having a thickness of 0.110 to 0.130 mm including the inner surface coating film, it has excellent piercing strength with a maximum load of 4.5 kgf or more and 5.5 kgf or less.
[0023]
The piercing strength was measured by applying an internal pressure of 200 kPa from the inside of the molded can body to a wall portion having a thickness of 0.110 to 0.130 mm including the outer coating film and the inner coating film, and having a tip radius of The maximum load when a protrusion having a diameter of 0.5 mm and a diameter of 1 mm was pierced at a speed of 50 mm / min and penetrated was determined as an average value of ten measurements (n = 10).
[0024]
【Example】
Hereinafter, examples of the present invention will be described in comparison with comparative examples. These examples show one embodiment of the present invention, and the present invention is not limited thereto.
[0025]
Example 1
The ingot of the aluminum alloy for a can body having the composition shown in Table 1 obtained by semi-continuous casting was subjected to homogenization treatment and hot rolling according to a conventional method, and then subjected to cold rolling without intermediate annealing. A cold-rolled plate having a thickness of 0.3 mm was obtained.
[0026]
Using the obtained cold-rolled sheet as a test material, the distribution density of the intermetallic compound and the area ratio thereof were measured. Table 1 shows the measurement results. In the measurement, after the surface of the aluminum alloy plate was degreased and washed, the surface of the plate was photographed with a composition image of a scanning electron microscope (SEM), and the particle size distribution of the intermetallic compound was analyzed by an image analyzer (Lizex 500 manufactured by Nireco Co., Ltd.). ). In this case, the diameter of the intermetallic compound was measured as a circle equivalent diameter, that is, the diameter of a circle having the same area as the area of the intermetallic compound in the photograph.
[0027]
Next, after the test material was coated with the amount of oil shown in Table 2, it was molded into a can body having a wall thickness shown in Table 2 according to the normal can body forming step, and the can body was formed according to the above-described measurement method. The tensile strength, elongation, and piercing strength of the wall portion were determined, and the can bottom pressure was also measured. Table 2 shows the results.
[0028]
As can be seen from Table 2, the can body formed from the test material according to the present invention has a wall tensile strength of more than 290 MPa and not more than 330 MPa, an elongation of 3% or more and less than 6%, and a withstand pressure of the can bottom. At 600 kPa or more, it had sufficient strength as a can body, and the piercing strength showed an excellent value of 4.5 kgf or more.
[0029]
[Table 1]

[0030]
[Table 2]

[0031]
Comparative Example 1
The ingot of the aluminum alloy for can body having the composition shown in Table 3 obtained by semi-continuous casting was homogenized according to a conventional method, hot-rolled, and then subjected to cold annealing without alloy annealing except for alloy M. Rolling was performed to obtain a cold-rolled plate having a thickness of 0.3 mm.
[0032]
Using the obtained cold-rolled sheet as a test material, the distribution density of the intermetallic compound and its area ratio were measured in the same manner as in Example 1. Table 3 shows the measurement results. In Table 3, those out of the conditions of the present invention are underlined.
[0033]
Next, after the test material was coated with the oil amount shown in Table 4, it was molded into a can body having a wall thickness shown in Table 4 according to the normal can body forming step, and the can body was formed according to the above-described measurement method. The tensile strength, elongation, and piercing strength of the wall portion were determined, and the can bottom pressure was also measured. Table 4 shows the results.
[0034]
[Table 3]

<< Table Note >> The aluminum alloy sheet M was subjected to intermediate annealing after hot rolling.
[Table 4]

[0036]
As shown in Table 4, the test material No. Since No. 11 has a small amount of Si, the strength of the can body becomes too large and the piercing resistance is inferior. Test material No. In No. 12, since the amount of Si and the amount of Mg are small, no elongation is obtained and the piercing resistance is poor. Test material No. 13 has a large amount of Si, so the elongation becomes too high and the strength is reduced. Test material No. Test material No. 14 has a small amount of Mg. No. 15 does not have sufficient strength as a can body because of the small amount of Mn. Test material No. In No. 16, since the distribution of the intermetallic compound is large, softening progresses in the heat treatment in the step of forming the can body, and sufficient strength cannot be obtained as the can body. Test material No. No. 17 is obtained by performing intermediate annealing after hot rolling, in which the distribution of the intermetallic compound is reduced and the piercing resistance is inferior.
[0037]
【The invention's effect】
According to the present invention, without changing the wall thickness of the wall of the current thin can, that is, without changing the weight of the can body, it is possible to apply the current mold and form the can body. Provided is an aluminum alloy plate for a can body having excellent stab resistance, which can maintain the strength of the can body at the current level and obtain a can body having excellent stab resistance.

Claims

Mn: 0.8 to 1.2% (mass%, the same applies hereinafter), Mg: 1.0 to 1.3%, Si: more than 0.3% to 0.45% or less, Fe: 0.3 to 0 Aluminum alloy having a composition of 0.5%, the balance consisting of Al and impurities, and a 0.275 to 0.325 mm thick cold-rolled aluminum alloy sheet which has been hot-rolled and then cold-rolled without intermediate annealing. An aluminum alloy plate obtained by applying re-oiling at a coating amount of more than 150 mg / m ² and 300 mg / m ² or less, wherein an intermetallic compound having a diameter (equivalent circle diameter) of 1 to 10 μm on the surface of the alloy plate is 3500 to 3500 μm. It is characterized by being distributed at a density of 4500 pieces / mm ² and an area ratio of 1 to 3%. In a can body forming process including DI processing and coating, the thickness including the outer surface and inner surface coating is 0.110 to 0.110. When molded into a can body with a 0.130 mm wall, In the can-axis direction of the section, elongation is 3% or more and less than 6%, tensile strength of penetration resistance excellent can barrel for an aluminum alloy sheet is less than 330MPa exceed 290 MPa.

In the can body forming process including DI processing and coating, when the can body having a wall portion having a thickness of 0.110 to 0.130 mm including the outer surface and the inner surface coating is formed into a can body having an inner pressure of 200 kPa from the inside of the can body. 2. The anti-load according to claim 1, wherein a maximum load is 4.5 to 5.5 kgf when a projection having a tip radius of 0.5 mm is pierced and penetrated into the wall at a speed of 50 mm / min. Aluminum alloy plate for can body with excellent piercing properties.