JP3733566B2

JP3733566B2 - Manufacturing method of aluminum alloy coated tab material with excellent bending workability

Info

Publication number: JP3733566B2
Application number: JP2001355464A
Authority: JP
Inventors: 佐久間尚幸; 小松原俊雄
Original assignee: Furukawa Sky Aluminum Corp
Current assignee: Furukawa Sky Aluminum Corp
Priority date: 2001-11-21
Filing date: 2001-11-21
Publication date: 2006-01-11
Anticipated expiration: 2021-11-21
Also published as: JP2003155546A

Description

【０００１】
【発明が属する技術分野】
本発明はビール、炭酸飲料、果汁飲料さらには日用雑貨用アルミニウム缶のタブ材に適した曲げ加工性に優れたアルミニウム合金塗装タブ材の製造方法に関するものである。
【０００２】
【従来の技術】
アルミニウム合金タブ材には、ＪＩＳ５０８２合金や５１８２合金が一般に用いられている。
アルミニウム缶に用いられているタブは、アルミニウム合金板をプレスによりタブの形状に打ち抜き、内側の指掛け部分を打ち抜き、強度を与えるために内縁部の折り返しや外周部の１８０度曲げを行って製造する。
また、耐食性や美観向上のために塗装下地処理を施した後に、表面にクリア塗料などを塗装焼付することが広く行われている。
このようにしてできたタブは、別途製造した蓋のリベット部に結合して缶蓋となる。
【０００３】
【発明が解決しようとする課題】
消費者が缶をあける時には、タブを持ち上げて缶蓋の開口部に梃子の原理で力を加えて開缶させるが、この時、タブ全体には曲げ応力が働くとともに、タブのリベット部との結合部分はタブを持ち上げる時に曲げられ、戻される時に逆方向に曲げ戻しされる。さらに一回では十分に開ききらない場合にはタブの持ち上げ・戻しが数回繰り返して行われる。
このようなタブ材に対して、近年ではコスト削減の一環で材料の薄肉化の要求が進んでおり、特に欧米においては薄肉化しても十分な強度を持つように素材の高強度化の要請が強い。
しかし、単に高強度を狙うと曲げ性が低下し、開缶時にタブが折れて缶が開かないことがまれに生じる。このため、成形時の曲げ加工性や開缶時の繰り返し曲げ性に優れた材料、すなわち開缶時にタブ折れの発生しない素材が求められている。
そこで、本発明は曲げ加工性に優れており、曲げ加工時に割れが発生せず、この割れに起因するタブ折れの無いアルミニウム合金板を提供することを目的とするものである。
【０００４】
【課題を解決するための手段】
上記の課題を解決するために、本発明者らが種々実験、検討を重ねた結果、合金成分と熱間圧延及び冷間圧延条件を制御することで、曲げ加工性を向上させ、それによりタブ折れの発生しない材料を開発し、本発明に至った。
すなわち本発明の曲げ加工性に優れたアルミニウム合金塗装タブ材の製造方法は、Ｍｇ３．５〜５．５％（質量％、以下同様）、Ｍｎ０．０１〜０．５５％、Ｓｉ０．０２〜０．２０％、Ｃｕ０．０１〜０．３５％、Ｃｒ０．０１〜０．１５％を含有し、Ｆｅ０．４０％以下、Ｔｉ０．０５％以下に規制し、残部がＡｌ及び不可避的不純物からなるＡｌ合金鋳塊を均質化処理を兼ねた加熱処理を施し、（１）最終パスの圧下率：３５〜６０％（２）最終パスの圧延速度：１５０ｍ／分以上（３）最終パス完了後の板の実体温度：２６０〜３４０℃（４）熱間圧延上り板厚：１．８〜３．４ｍｍ（５）熱間圧延板の再結晶率：９０％以上の条件を満たすように熱間圧延を行った後、最終板厚までは焼鈍を行わず、８０〜９１％の圧延率で冷間圧延を行うことを特徴とする。
【０００５】
【発明の実施の形態】
以下、本発明の各要素の限定理由について説明する。
先ず、この発明における合金成分の限定理由について説明する。
【０００６】
Ｍｇ：Ｍｇの添加は、Ｍｇそれ自体の固溶による強度向上があり、また、転位との相互作用が大きいために加工硬化による強度向上が期待でき、タブ材としての必要な強度を得るためには不可欠な元素である。しかし、Ｍｇ添加量が３．５％未満では十分な強度を得ることができない。一方、５．５％を超えると冷間圧延によって導入される転位密度が多くなり過ぎ、成形中にタブが割れてしまう。更に、本発明プロセスの場合には、熱間圧延を行った後は最終板厚までは焼鈍を行わないため、Ｍｇ量が過剰では冷間圧延性を阻害してしまう。そのため、Ｍｇ添加量を３．５〜５．５％の範囲とした。
【０００７】
Ｍｎ：Ｍｎの添加は強度向上と塗装焼付け時の軟化抑制に大きな効果がある。そのため、少なくとも０．０１％以上の添加が必要である。一方、０．５５％を超えるとＡｌ−Ｍｎ−(Ｓｉ)、Ａｌ−Ｆｅ−Ｍｎ−(Ｓｉ)系金属間化合物の生成と粗大化が起こる。この金属間化合物の延性はアルミニウムマトリックスに比べて極端に低いため、成形中に材料の割れを引き起こしてしまう。従って、Ｍｎ添加量を０．０１〜０．５５％の範囲にした。
【０００８】
Ｓｉ：Ｓｉの添加は塗装焼付け時の軟化抑制に大きな効果がある。そのため、少なくとも０．０２％以上の添加が必要である。一方、０．２０％を超えるとＡｌ−Ｍｎ−Ｓｉ、Ａｌ−Ｆｅ−Ｍｎ−ＳｉさらにはＭｇ_２Ｓｉ金属間化合物の生成と粗大化が生じ、成形性を劣化させてしまう。従って、Ｓｉ添加量を０．０２〜０．２０％の範囲にした。
【０００９】
Ｃｕ：Ｃｕの添加は強度向上と塗装焼付け時の軟化抑制に大きな効果がある。しかし、添加量が０．０１％未満では、その効果は現れない。一方、０．３５％を超える場合には、冷間圧延によって導入される転位密度が多くなり過ぎ、成形中にタブが割れてしまう。更に、本発明プロセスの場合には、熱間圧延を行った後は最終板厚までは焼鈍を行わないため、Ｃｕ添加量が過剰では冷間圧延性を阻害してしまう。そのため、Ｃｕ添加量を０．０１〜０．３５％の範囲にした。
【００１０】
Ｃｒ：Ｃｒの添加は強度向上と塗装焼付け時の軟化抑制に大きな効果がある。しかし、添加量が０．０１％未満では、その効果は現れない。一方、０．１５％を超える場合には、冷間圧延によって導入される転位密度が多くなり過ぎる。また、Ａｌ−Ｃｒ系の金属間化合物の生成と粗大化が起こり、その結果、成形中にタブが割れてしまう。更には、冷間圧延性も阻害してしまう。そのため、Ｃｒ添加量を０．０１〜０．１５％の範囲とした。
【００１１】
Ｆｅ：Ｆｅの添加は塗装焼付け時の軟化抑制に大きな効果がある。しかし、０．４０％を超えるとＡｌ−Ｆｅ−Ｍｎ−(Ｓｉ)系金属間化合物の生成と粗大化が起こり、成形性を劣化させてしまう。従って、Ｆｅ添加量を０．４０％以下に規制した。
【００１２】
Ｔｉ：Ｔｉは結晶粒の微細化に有効な元素であるが、添加量が多いと鋳塊組織を羽毛状晶になり難くし、粒状晶を生成しやすくする。粒状晶の場合には、羽毛状晶の場合よりも粒界に晶出する金属間化合物を粗大化させたり、それ自体、粗大金属間化合物を生成してしまい、その結果、成形性を劣化させてしまう。従って、Ｔｉ量を０．０５％以下に規制した。
尚、ＴｉにＢを加えて添加する場合もあるが、その時のＢ量は１００ｐｐｍ以下に規制することが望ましい。
【００１３】
次に本発明の製造プロセスについて説明する。
【００１４】
本発明プロセスは熱間圧延で焼鈍を兼ね、熱間圧延を行った後は最終板厚までは焼鈍を行わないものである。そのため、以下に列挙する熱間圧延、冷間圧延の制御は曲げ加工性や生産性の観点から非常に重要な役割を果たす。
【００１５】
（１）最終パスの圧下率：３５〜６０％最終パスの圧下率が３５％未満では再結晶に対する駆動力が小さすぎ、熱間圧延板の再結晶率の規定を満たせず、熱間圧延で残存した転位密度が高くなる。本発明においては熱間圧延を行った後は最終板厚までは焼鈍を行わないため、最終板の転位密度は［熱間圧延で残存した転位密度］＋［冷間圧延によって導入された転位密度］となる。このうち熱間圧延で残存した転位密度分は過剰で、この過剰転位密度は曲げ加工性を劣化させてしまう。一方、６０％を超える圧下率では、熱間圧延中に板切れが生じてしまうこともある。また、クーラントの焼付きによる板表面のコーティングが発生して製品としての価値を失うこともある。そこで、最終パスの圧下率を３５〜６０％にした。
【００１６】
（２）最終パスの圧延速度：１５０ｍ／分以上
最終パスの圧延速度が１５０ｍ／分未満であると、圧下率と同様に再結晶に対する駆動力が小さすぎ、熱間圧延板の再結晶率の規定を満たさなくなり、上記と同様に良好な曲げ加工性を有する材料はできない。
【００１７】
（３）最終パス完了後の板の実体温度：２６０〜３４０℃
本発明においては最終パス完了後の板の実体温度を２６０℃以上とすることにより、再結晶を促進する。
この温度が２６０℃未満では、熱間圧延後のコイル冷却中などで生じる再結晶が起こり難く、一方３４０℃を超える場合には再結晶に対しては有利であるが、クーラントの焼付きによるコーティングが発生して製品としての価値を失う。そのため、最終パス完了後の板の実体温度を２６０〜３４０℃の範囲にした。
【００１８】
（４）熱間圧延上り板厚：１．８〜３．４ｍｍ熱間圧延上り板厚が１．８ｍｍ未満では、熱間圧延中の温度低下の影響が極端に大きくなり、最終パス完了後の板の実体温度が２６０℃を下回ってしまい、熱間圧延板の再結晶率の規定を満たすことができなくなる。一方、３．４ｍｍを超える場合には、所定の製品板厚とするには総冷間圧延率が高くなり過ぎ、冷間圧延によって導入される転位密度が過剰になり、その結果、良好な曲げ加工性を有するタブ材ができない。そこで、熱間圧延上り板厚を上記の範囲にした。
【００１９】
（５）熱間圧延板の再結晶率：９０％以上本発明においては熱間圧延を行った後は最終板厚までは焼鈍を行わないため、最終板の転位密度は［熱間圧延で残存した転位密度］＋［冷間圧延によって導入された転位密度］となる。熱間圧延板の再結晶率が９０％未満では熱間圧延で残存する転位密度が高くなりすぎ、その結果、転位密度が過剰になり曲げ加工性を劣化させてしまう。従って、熱間圧延の残存転位密度を少なくするために、再結晶率は上記の範囲とした。尚、再結晶率は光学顕微鏡を使用して熱間圧延板の圧延方向断面で測定した。
【００２０】
次に冷間圧延率の規定について説明する。冷間圧延率が８０％未満では、タブ材に必要とする強度が得らず、一方９１％を超える圧延率では冷間圧延によって導入される転位密度が過剰になり、良好な曲げ加工性を有する材料ができない。そこで、冷間圧延率は８０〜９１％の範囲に規定した。
【００２１】
上記の条件を満たして製造した冷間圧延板に対して、１００〜２４０℃の温度範囲で保持１〜１０時間の調質焼鈍を行う理由について説明する。１００℃未満では調質焼鈍の効果が充分に得られない。調質焼鈍の効果には、伸びを増加させ、更なる曲げ加工性の向上が期待できる。一方、２４０℃を超える温度では、材料軟化が大きくなり過ぎてタブ材として要求される強度を満たさなくなる。また、保持１時間未満では、コイル全体に渡って均一な熱処理ができない。これに対し、１０時間を超えると生産性の低下を招くだけでなく、強度不足を引き起こしてしまう。そのため、調質焼鈍の条件を上記の通りにした。
【００２２】
【実施例】
表１に示す種々の化学成分のアルミニウム合金鋳塊を、表２で記載したプロセスで製造し最終板厚０．３０ｍｍに仕上げて、水性塗料を塗装し、２５０℃×２４ｓで焼き付け処理した。
表１の（１）、（２）は本発明の成分範囲の合金であり、（３）〜（７）は本発明の規定を外れた成分の合金である。
【００２３】
【表１】

【００２４】
【表２】

【００２５】
得られた塗装板に対して、各特性を評価した。
加工性の評価は、タブを１００個作製し、割れがひどく形状不良が発生して、開口時に１個でもタブが折れた場合を不合格（×）にした。
また、塗装後の材料強度（耐力）も評価し、耐力が２７０ＭＰａを下回る場合には、強度不足のために開缶時にタブが曲がってしまうなどの開口不良が生じたので不合格にした。
尚、加工性は缶胴に炭酸水を入れて炭酸飲料用缶蓋で密封し、その蓋にタブを取り付けて、実際に開口試験を行い評価した。
その結果を表３に示す。
【００２６】
【表３】

【００２７】
表３に示すように、発明例であるＮｏ．１、Ｎｏ．４はタブ折れが一つもなく良好な加工性を示しており、また材料強度も充分であり、タブとして使用するのに好適な特性を示している。これに対して合金成分組成は本発明の規定内だが、製造条件が外れているＮｏ．２、Ｎｏ．３は強度は充分であるもののタブ折れが発生しており、曲げ加工性が悪くなっている。またＮｏ．６〜８は製造条件は本発明の規定を満たしているが合金成分が本発明の条件を外れているため、強度は充分であるものの、タブ折れが発生してしまい、曲げ加工性が悪いものとなっている。さらにＮｏ．９はＭｇ量の少ない合金組成であり、曲げ加工性は良くタブ折れは発生していないが、強度不足になってしまい、開缶時にタブが曲がってしまい開口不良が発生している。
【００２８】
【発明の効果】
以上述べたように、本発明によれば、板厚を薄くしても成形過程での曲げＲ部の割れの発生が無く、また消費者が蓋を開ける時にタブが折れてしまうことも無い、曲げ加工性と強度に優れたアルミニウム合金タブ材を提供することができる。
また本発明は熱間圧延を行った後は最終板厚までは焼鈍を行わないため、製造期間の短縮、コスト削減などの生産性向上も図ることができる。[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for producing an aluminum alloy coated tab material excellent in bending workability suitable for beer, carbonated beverages, fruit juice beverages, and tab materials for aluminum cans for daily goods.
[0002]
[Prior art]
JIS5082 alloy and 5182 alloy are generally used for the aluminum alloy tab material.
The tab used in the aluminum can is manufactured by punching an aluminum alloy plate into a tab shape by pressing, punching out the inner finger-hanging portion, folding the inner edge portion and bending the outer periphery portion to give strength. .
In addition, it is widely practiced to paint and bake a clear coating or the like on the surface after applying a coating base treatment for improving corrosion resistance and aesthetics.
The tab thus formed is combined with a rivet portion of a lid manufactured separately to become a can lid.
[0003]
[Problems to be solved by the invention]
When a consumer opens a can, the tab is lifted and force is applied to the opening of the can lid in accordance with the principle of the lever. At this time, bending stress acts on the entire tab, and the rivet portion of the tab The coupling portion is bent when lifting the tab and bent back in the opposite direction when returned. Further, when the opening cannot be fully achieved at one time, the tab is repeatedly lifted and returned several times.
In recent years, there has been a demand for such a tab material to reduce the thickness of the material as part of cost reduction. Especially in Europe and the United States, there is a demand for higher strength of the material so that it has sufficient strength even if the thickness is reduced. strong.
However, if a high strength is simply aimed at, the bendability is lowered, and in rare cases, the tab may break when the can is opened and the can does not open. For this reason, a material excellent in bending workability at the time of molding and repeated bendability at the time of can opening, that is, a material that does not cause tab breakage at the time of can opening is required.
Accordingly, an object of the present invention is to provide an aluminum alloy plate that is excellent in bending workability, does not generate cracks during bending, and has no tab breaks due to the cracks.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have conducted various experiments and examinations, and as a result, the bending workability is improved by controlling the alloy components and the hot rolling and cold rolling conditions, thereby improving the tabs. A material that does not bend has been developed, and the present invention has been achieved.
That is, the manufacturing method of the aluminum alloy coating tab material excellent in bending workability of the present invention is Mg 3.5 to 5.5% (mass%, the same applies hereinafter), Mn 0.01 to 0.55%, Si 0.02 to 0 .20%, Cu 0.01 to 0.35%, Cr 0.01 to 0.15%, Fe 0.40% or less, Ti 0.05% or less, the balance is Al and Al consisting of inevitable impurities The alloy ingot is subjected to a heat treatment that also serves as a homogenization treatment. (1) Rolling rate of the final pass: 35 to 60% (2) Rolling speed of the final pass: 150 m / min or more (3) Plate after completion of the final pass (4) Hot rolled ascending sheet thickness: 1.8 to 3.4 mm (5) Recrystallization ratio of hot rolled sheet: Hot rolling so as to satisfy the condition of 90% or more After it is done, it is not annealed until the final plate thickness, and the cold pressure is 80% to 91%. And performing.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the reason for limitation of each element of the present invention will be described.
First, the reasons for limiting the alloy components in the present invention will be described.
[0006]
Mg: Addition of Mg has improved strength due to solid solution of Mg itself, and because of the large interaction with dislocations, it can be expected to improve strength by work hardening, in order to obtain the necessary strength as a tab material Is an indispensable element. However, if the amount of Mg added is less than 3.5%, sufficient strength cannot be obtained. On the other hand, if it exceeds 5.5%, the dislocation density introduced by cold rolling becomes too large, and the tab breaks during molding. Furthermore, in the case of the process of the present invention, after hot rolling, annealing is not performed up to the final sheet thickness, so if the amount of Mg is excessive, cold rolling properties are impaired. Therefore, the amount of Mg added is set in the range of 3.5 to 5.5%.
[0007]
Mn: Addition of Mn has a great effect on strength improvement and suppression of softening during baking. Therefore, it is necessary to add at least 0.01% or more. On the other hand, when it exceeds 0.55%, generation and coarsening of Al—Mn— (Si) and Al—Fe—Mn— (Si) intermetallic compounds occur. Since the ductility of this intermetallic compound is extremely lower than that of the aluminum matrix, it causes cracking of the material during molding. Therefore, the amount of Mn added is in the range of 0.01 to 0.55%.
[0008]
Si: The addition of Si has a great effect in suppressing softening during paint baking. Therefore, addition of at least 0.02% or more is necessary. On the other hand, if it exceeds 0.20%, Al—Mn—Si, Al—Fe—Mn—Si, and further Mg ₂ Si intermetallic compounds are generated and coarsened, and the formability is deteriorated. Therefore, the Si addition amount is set to 0.02 to 0.20%.
[0009]
Cu: The addition of Cu has a great effect in improving the strength and suppressing the softening during baking. However, if the added amount is less than 0.01%, the effect does not appear. On the other hand, when it exceeds 0.35%, the dislocation density introduced by cold rolling becomes too large, and the tab is cracked during molding. Furthermore, in the case of the process of the present invention, after hot rolling, annealing is not performed up to the final plate thickness, so if the amount of Cu is excessive, cold rolling properties are impaired. Therefore, the amount of Cu added is set in the range of 0.01 to 0.35%.
[0010]
Cr: The addition of Cr has a great effect on strength improvement and suppression of softening during paint baking. However, if the added amount is less than 0.01%, the effect does not appear. On the other hand, when it exceeds 0.15%, the dislocation density introduced by cold rolling becomes too large. Moreover, the production | generation and coarsening of an Al-Cr type | system | group intermetallic compound occur, As a result, a tab will crack during shaping | molding. Furthermore, cold rollability is also impaired. Therefore, the Cr addition amount is set to a range of 0.01 to 0.15%.
[0011]
Fe: Addition of Fe has a great effect on softening suppression during paint baking. However, if it exceeds 0.40%, the production and coarsening of Al—Fe—Mn— (Si) -based intermetallic compounds occur, and formability is deteriorated. Therefore, the amount of Fe added is regulated to 0.40% or less.
[0012]
Ti: Ti is an effective element for refining crystal grains. However, if the addition amount is large, the ingot structure is less likely to become feathery crystals, and granular crystals are easily generated. In the case of granular crystals, the intermetallic compounds that crystallize at the grain boundaries become coarser than in the case of feathery crystals, or the coarse intermetallic compounds themselves are formed, resulting in deterioration of moldability. End up. Therefore, the Ti content is regulated to 0.05% or less.
In some cases, B may be added to Ti, but the amount of B at that time is preferably regulated to 100 ppm or less.
[0013]
Next, the manufacturing process of the present invention will be described.
[0014]
The process of the present invention also serves as annealing by hot rolling, and after hot rolling, annealing is not performed up to the final thickness. Therefore, control of hot rolling and cold rolling listed below plays a very important role from the viewpoint of bending workability and productivity.
[0015]
(1) Rolling ratio of the final pass: 35 to 60% If the rolling reduction ratio of the final pass is less than 35 %, the driving force for recrystallization is too small, and the recrystallization rate of the hot rolled sheet is not satisfied. The residual dislocation density increases. In the present invention, after hot rolling, annealing is not performed until the final thickness, so the dislocation density of the final plate is [dislocation density remaining in hot rolling] + [dislocation density introduced by cold rolling] ]. Among these, the dislocation density remaining in the hot rolling is excessive, and this excess dislocation density deteriorates the bending workability. On the other hand, if the rolling reduction exceeds 60%, the sheet may be cut during hot rolling . In addition, coating of the surface of the plate due to seizure of the coolant may occur and lose its value as a product. Therefore, the rolling reduction of the final pass was set to 35 to 60%.
[0016]
(2) Rolling speed of the final pass: 150 m / min or more If the rolling speed of the final pass is less than 150 m / min, the driving force for recrystallization is too small as with the rolling reduction, and the recrystallization rate of the hot rolled sheet A material that does not satisfy the regulations and has good bending workability as described above cannot be produced.
[0017]
(3) Substrate temperature after completion of final pass: 260 to 340 ° C
In the present invention, recrystallization is promoted by setting the solid temperature of the plate after completion of the final pass to 260 ° C. or higher.
If this temperature is less than 260 ° C., recrystallization that occurs during coil cooling after hot rolling is difficult to occur, whereas if it exceeds 340 ° C., it is advantageous for recrystallization, but coating by seizure of coolant. Occurs and loses value as a product. For this reason, the solid temperature of the plate after completion of the final pass was set to a range of 260 to 340 ° C.
[0018]
(4) Hot rolled up plate thickness: 1.8 to 3.4 mm When the hot rolled up plate thickness is less than 1.8 mm, the influence of temperature drop during hot rolling becomes extremely large, and after the final pass is completed. The actual temperature of the plate falls below 260 ° C., and the regulation of the recrystallization rate of the hot rolled plate cannot be satisfied. On the other hand, if it exceeds 3.4 mm, the total cold rolling rate becomes too high to obtain a predetermined product sheet thickness, and the dislocation density introduced by cold rolling becomes excessive, resulting in good bending. Tab material with workability cannot be made. Therefore, the hot rolled up plate thickness is set to the above range.
[0019]
(5) Recrystallization ratio of hot-rolled sheet: 90% or more In the present invention, after hot rolling, annealing is not performed to the final sheet thickness, so the dislocation density of the final sheet is [remaining in hot rolling Dislocation density] + [dislocation density introduced by cold rolling]. If the recrystallization rate of the hot-rolled sheet is less than 90%, the dislocation density remaining in the hot rolling becomes too high. As a result, the dislocation density becomes excessive and the bending workability is deteriorated. Therefore, in order to reduce the residual dislocation density in hot rolling, the recrystallization rate is set to the above range. In addition, the recrystallization rate was measured in the rolling direction cross section of the hot- rolled sheet using an optical microscope.
[0020]
Next, the regulation of the cold rolling rate will be described. If the cold rolling rate is less than 80%, the strength required for the tab material cannot be obtained. On the other hand, if the rolling rate exceeds 91%, the dislocation density introduced by the cold rolling becomes excessive, resulting in good bending workability. Can't have material. Therefore, the cold rolling rate is specified in the range of 80 to 91%.
[0021]
The reason for performing temper annealing for 1 to 10 hours holding in a temperature range of 100 to 240 ° C. on a cold rolled sheet manufactured while satisfying the above conditions will be described. If it is less than 100 ° C., the effect of temper annealing cannot be sufficiently obtained. The effect of temper annealing can be expected to increase elongation and further improve bending workability. On the other hand, at temperatures exceeding 240 ° C., material softening becomes too large to satisfy the strength required for the tab material. Further, if the holding time is less than 1 hour, uniform heat treatment cannot be performed over the entire coil. On the other hand, if it exceeds 10 hours, not only the productivity is lowered, but also the strength is insufficient. Therefore, the conditions for temper annealing were as described above.
[0022]
【Example】
Aluminum alloy ingots having various chemical components shown in Table 1 were produced by the process described in Table 2, finished to a final plate thickness of 0.30 mm, coated with water-based paint, and baked at 250 ° C. × 24 s.
In Table 1, (1) and (2) are alloys in the component range of the present invention, and (3) to (7) are alloys having components outside the scope of the present invention.
[0023]
[Table 1]

[0024]
[Table 2]

[0025]
Each characteristic was evaluated with respect to the obtained coated board.
For the evaluation of workability, 100 tabs were prepared, and cracks were severely generated, resulting in a defective shape. Even when one tab was broken at the time of opening, it was rejected (x).
Moreover, the material strength (proof strength) after coating was also evaluated, and when the proof strength was less than 270 MPa, it was rejected because an opening failure such as a bent tab at the time of opening the can due to insufficient strength.
The workability was evaluated by putting carbonated water into the can body, sealing it with a can lid for carbonated beverages, attaching a tab to the lid, and actually conducting an opening test.
The results are shown in Table 3.
[0026]
[Table 3]

[0027]
As shown in Table 3, No. 1 is an invention example. 1, no. No. 4 shows good workability without any tab breakage, and the material strength is sufficient, and it shows characteristics suitable for use as a tab. On the other hand, the alloy composition is within the limits of the present invention, but the manufacturing conditions are not. 2, No. No. 3 has sufficient strength, but tab breakage has occurred and bending workability is poor. No. In Nos. 6 to 8, the manufacturing conditions satisfy the provisions of the present invention, but the alloy components are outside the conditions of the present invention, so that the strength is sufficient, but tab breakage occurs and bending workability is poor. It has become. Furthermore, no. No. 9 is an alloy composition with a small amount of Mg, and the bending workability is good and tab breakage does not occur, but the strength is insufficient, and the tab is bent at the time of can opening, resulting in poor opening.
[0028]
【The invention's effect】
As described above, according to the present invention, even if the plate thickness is reduced, there is no occurrence of cracking of the bending R part in the molding process, and the tab does not break when the consumer opens the lid. An aluminum alloy tab material excellent in bending workability and strength can be provided.
In addition, since the present invention does not perform annealing to the final thickness after hot rolling, it is possible to improve productivity such as shortening the manufacturing period and reducing costs.

Claims

Mg 3.5-5.5% (mass%, the same applies hereinafter), Mn 0.01-0.55%, Si 0.02-0.20%, Cu 0.01-0.35%, Cr 0.01-0.15 (1) The final pass is subjected to a heat treatment that also serves as a homogenization treatment for an Al alloy ingot that contains Al and unavoidable impurities. rolling reduction: 35-60% (2) the rolling speed of the final pass: 150 meters / minute or higher (3) the final pass after the completion of the plate of substantial temperature: two hundred and sixty to three hundred forty ° C. (4) hot-rolled up sheet thickness: 1. 8 to 3.4 mm (5) Recrystallization ratio of hot-rolled sheet: After hot rolling so as to satisfy the condition of 90% or more, the final sheet thickness is not annealed, and the rolling is 80 to 91%. Made of aluminum alloy coated tab material with excellent bending workability, characterized by cold rolling at a high rate Method.

A method for producing an aluminum alloy coated tab material excellent in bending workability, characterized by performing temper annealing in a temperature range of 100 to 240 ° C and holding for 1 to 10 hours after cold rolling according to claim 1.