JP4273790B2 - Steel plate for thinned deep drawn ironing can with excellent pressure resistance - Google Patents

Description

【０００１】
【発明の属する技術分野】
本発明は耐圧強度に優れた薄肉化深絞りしごき缶用樹脂フィルムラミネート鋼板に関するものである。
【０００２】
【従来の技術】
スチール製飲料缶のうち、缶内部が陽圧状態で流通する陽圧缶には、ＤＩ(Drawn and Ironing)缶および薄肉化深絞りしごき缶が用いられている。従来はＤＩ缶が主流であったが、製缶工程での環境負荷が少ない利点から、今後は薄肉化深絞りしごき缶が大きく伸長していくと考えられる。
【０００３】
薄肉化深絞りしごき缶には、樹脂フィルムラミネート鋼板が用いられる。その原板には、当初Ｃ量０．１％を含む二回冷圧（以下ＤＲ）材が用いられた。その後、例えば特許文献１、特許文献２のように、Ｃ量を低減して加工性を向上させることで缶体を軽量化する技術が開発され、缶体コストの低減が図れられいる。
【０００４】
今後、薄肉化深絞りしごき缶のコスト低減はより一層の進展が求められ、さらなる軽量化が検討されている。
【０００５】
一方で、薄肉化深絞りしごき缶が用いられる陽圧缶では、内圧の上昇によって缶底部が挫屈する問題がある。挫屈限界の内圧は耐圧強度と呼ばれるが、これは缶底部の形状に支配されるとともに、鋼板の特性としては板厚と強度に依存することが知られている。
【０００６】
缶底部の形状は内圧に対して強い構造であるドーム状に加工されているものの、現状の薄肉化深絞りしごき缶用鋼板では軽量化を図る上で重要な板厚の低減や高加工度化を進めた場合、耐圧強度の低下が今後懸念される問題となる。
【０００７】
以上のように、薄肉化深絞りしごき缶の軽量化によってコスト低減を進めるためには、耐圧強度確保の問題を解決する必要があるが、いまだ十分な特性を持った薄肉化深絞りしごき缶用鋼板は提示されていない。
【０００８】
以下に先行技術文献情報について記載する。
【０００９】
【特許文献１】
特開平７−３４９１２号公報
【００１０】
【特許文献２】
特開平７−３４１９４号公報
【００１１】
【発明が解決しようとする課題】
本発明はこのような従来技術の現状を考慮して、耐圧強度に優れた薄肉化深絞りしごき缶用鋼板の提供を目的とするものである。
【００１２】
【課題を解決するための手段】
本発明者らは、耐圧強度に優れた薄肉化深絞りしごき缶用鋼板について種々の検討を行なった。その結果、軽量化と耐圧強度の両立を為し得る鋼板をはじめて見出したものである。すなわち、本発明の要旨は、以下のとおりである。
鋼成分が、質量％で、
Ｃ：０．０１〜０．０６％、
Ｍｎ：０．１〜０．６％、
Ａｌ：０．０１〜０．１０％、
Ｎ：０．００１０〜０．００５０％、
かつ、質量％で表したＡｌとＮの含有量の比Ａｌ／Ｎが２５以下、
残部Ｆｅおよび不可避的不純物からなり、
有機樹脂フィルムがラミネートされた二回冷圧の冷間圧延鋼板であって、
相当歪み０．２の加工と２１０℃で３分の加熱をこの順で行なった後の引張り強度の上昇量が８０ＭＰａ以上である、耐圧強度に優れた薄肉化深絞りしごき缶用鋼板。
【００１３】
なお、本明細書において、鋼成分を示す％は全て質量％である。
【００１４】
【発明の実施の形態】
以下に本発明を詳細に説明する。
【００１５】
本発明者らは、板厚低減あるいは高加工度化による軽量化と耐圧強度の確保を両立させ得る薄肉化深絞りしごき缶用鋼板について検討し、本発明に至った。その考え方は、以下のように説明できる。
【００１６】
薄肉化深絞りしごき缶には、冷間圧延後に再結晶焼鈍し、さらに二次圧延したＤＲ材の表面に電解クロメート処理したティンフリー鋼板（ＴＦＳ）に対して加熱下で樹脂フィルムをラミネートした鋼板を用いる。
【００１７】
製缶加工は、後方張力を付加しつつ小径のダイ肩部での曲げ曲げ戻し加工により薄肉化を行う薄肉化深絞りと、これにしごき加工を組み合わせた方式で行われ、缶底部をドーム状に加工した後、フィルム表面に塗布されたワックスの除去とフィルムの加工歪みを除去する目的で加熱処理を施す。
【００１８】
このドーム加工によって鋼板には新たな歪みによる転位が導入され、続く加熱処理で鋼板中の固溶元素が拡散して転位を固着することで、ドーム部は歪み時効硬化する。耐圧強度はこうした一連の製缶工程後の強度に依存するため、耐圧強度を確保するためにはこの歪み時効硬化を有効に利用することが重要になる。
【００１９】
薄肉化深絞りしごき缶にはＤＲ材が用いられている。ＤＲ材には鋼板内に多くの転位が存在するが、加熱下で有機樹脂フィルムがラミネートされるため、この加熱段階で多くの固溶元素が転位の固着に消費されている。転位の固着に作用する固溶元素としてはＣとＮがあるが、Ｎに比べて拡散の早いＣがこの段階で主に転位を固着する固溶元素となる。
【００２０】
また、缶体を原板板厚低減あるいは高加工度化で軽量化した場合、必然的に缶体の熱容量が減少し、加熱処理時の熱履歴が変化する。特に、固溶元素の拡散による転位の固着が進行する加熱時の昇温段階において、軽量化された缶体は従来よりも早く缶体の温度が上昇し、結果として比較的高い温度で保持される時間が長くなることがわかった。
【００２１】
以上のことから、ＤＲ材が用いられる薄肉化深絞りしごき缶用鋼板では、軽量化された缶体において耐圧強度の確保のために歪み時効硬化を有効に利用する場合、比較的高温での歪み時効硬化に有効なＮの作用を利用することが重要であることがわかった。つまり、本発明の成分で重要なＡｌ量およびＮ量およびＡｌ／Ｎで表される両者のバランスを適切にすることで耐圧強度を有効に確保できるとの知見に至った。
【００２２】
ここで、相当歪み０．２の加工と２１０℃で３分間の加熱をこの順で行った後の引張強度の上昇量を、耐圧強度の指標とした理由を述べる。
【００２３】
缶底のドーム加工部において、缶内圧を上昇させた場合に最初に挫屈する箇所は、接地部の内側の付け根である。当該部は、ドーム加工により歪みを導入された後に加熱処理を受けるため歪み時効硬化を生じ、製缶前の平板の時点よりも強度を増す。すなわち、十分な耐圧強度を確保するためには、当該部のドーム加工及び加熱処理による強度上昇量に注目する必要がある。詳細な調査を行ったところ、当該部の歪み量は相当歪み０．２に相当し、また、加熱処理による歪み時効硬化量は２１０℃で３分間の加熱で再現できることを見出した。
【００２４】
図１は、Ａｌ、Ｎ量が種々に異なる薄肉化深絞りしごき缶用鋼板に相当歪み０．２の加工を圧延によって施し、これをＪＩＳ−５号引張り試験片に加工し、２１０℃で３分の加熱処理を施した後に引張り試験した際の引張り強度の上昇量と、試作した薄肉化深絞りしごき缶の耐圧強度の関係を示した図である。ここで、耐圧強度は基準値からの差（測定値−基準値）で示した。また、缶体は一般的な陽圧缶よりも板厚を約８％低減した軽量缶を試作している。図１に示すように、引張強度の上昇量が８０ＭＰａ以上の場合に、試作した軽量缶においても、一般的な陽圧缶において必要とされる基準値よりも大きい耐圧強度を達成できることがわかる。
【００２５】
図２は、Ａｌ、Ｎ量が種々に異なる薄肉化深絞りしごき缶用鋼板に相当歪み０．２の加工を圧延によって施し、これをＪＩＳ−５号引張り試験片に加工し、２１０℃で３分の加熱処理を施した後に引張り試験した際の引張り強度の上昇量と、Ａｌ／Ｎとの関係を示す図である。図１で示した８０ＭＰａ以上の引張り強度の上昇量は、Ａｌ／Ｎを２５以下とすることで得られることがわかる。
【００２６】
次に、本発明の鋼成分の限定理由について説明する。
【００２７】
Ｃは鋼板の強度調整のために重要な元素である。０．０１％未満では薄肉化深絞りしごき缶用鋼板として具備すべき強度を確保できず、また、０．０６％超えでは鋼板が過剰に硬質化して加工性自体が損なわれることから、０．０１％〜０．０６％とした。
【００２８】
Ｍｎは鋼板の強度調整と熱間脆性の防止を主目的に添加されるが、０．１％未満では目的が達せられず、また０．６％を超えると鋼板が過剰に硬質化して製缶加工性自体を損ねる。したがって０．１〜０．６％とする。上記作用と成分制御の観点から、望ましくは０．１５〜０．５５％である
Ａｌは溶鋼の脱酸およびＮの固定を目的に添加されるが、本発明ではＮとの関係で重要な元素である。その量が０．０１％未満では目的が十分に達成されず、また０．１０％を超えるとその効果が飽和するとともに、非金属介在物を増加させて表面傷の原因となるので、Ａｌ量は０．０１〜０．１０％とする。上記作用と成分制御の観点から、望ましくは０．０３〜０．０６％である。
【００２９】
ＮはＡｌとともに本発明で重要な元素である。Ｎを０．００１０％未満とすると、本発明の主眼である歪み時効硬化を発揮できないだけでなく、製鋼での脱Ｎ処理時間がかさみ、介在物混入の危険性が高まることに加えてコスト上昇を招くことになり、経済性上好ましくない。また、０．００５０％を超えると鋼板自体の強度が過剰に上昇するため、その上限を０．００５０％とする。上記作用と成分制御の観点から、望ましくは０．００１５〜０．００３０％である。
【００３０】
本発明では、上記Ａｌ、Ｎの量的な関係をＡｌ／Ｎで２５以下とする。Ｎは熱延や焼鈍段階でＡｌＮとして析出するが、その際、製缶加工後に施される加熱処理においてＮによる歪み時効硬化を発揮するために析出しないＮが残存していることが必要である。Ａｌ／Ｎを２５以下とすることで、製缶加工後に施される加熱処理で歪み時効硬化を発揮するのに必要な量のＮが残存し、図２に示すように、引張り強度の上昇量を８０ＭＰａ以上にでき、もって成型した缶の耐圧強度を基準値以上にできるようになる。
【００３１】
上記成分の他、鋼にはＳｉ、Ｐ、Ｓ等が含まれるが、これらの成分は特に本発明の鋼板特性に影響を及ぼすことないため、その他の特性に影響がない範囲で適宜含むことができる。また、特性に悪影響を及ぼさない範囲で、上記以外の元素の添加を行なうこともできる。
【００３２】
次に、本発明の鋼板の製造方法について説明する。
【００３３】
製鋼条件、鋳片の製造条件は、本発明に規定する鋼成分が得られる方法であれば如何なる方法でもよく、特に規定しないが、鋳片の製造は、鋳片の均一性から、連続鋳造で行なうことが望ましい。鋳片の加熱条件も特に規定するものではないが、加熱温度は窒化物の再溶解を促進する意味で１２５０℃以上とすることが望ましい。
【００３４】
熱延条件も特に規定するものではないが、熱延鋼板の均一性、表面性状、機械特性から、仕上温度は８７０℃以上とすることが望ましい。また、巻取り温度は同様の理由から５６０〜６４０℃が望ましい。
【００３５】
酸洗、冷間圧延、再結晶焼鈍条件は特に規定しないが、焼鈍条件は経済的な観点から連続焼鈍が望ましい。
【００３６】
二次圧延条件も特に規定しないが、鋼板の板厚制御、機械特性、異方性の観点から圧延率は５〜２０％であることが望ましい。
【００３７】
表面処理は、有機樹脂フィルムをラミネートする下地として適当であればいかなるものでも差し支えないが、耐食性、フィルム密着性の観点から、ＴＦＳまたはこれに類する電解クロメート処理が望ましい。
【００３８】
有機樹脂フィルム、およびラミネート条件は、薄肉化深絞りしごき缶用鋼板として具備すべき特性を備える限り、特にこれを規定しないが、ラミネートは加熱下で行うことが好ましい。
【００３９】
また、本発明の鋼板特性を特徴づける相当歪み０．２の加工と２１０℃で３分の加熱処理については、その付与の方法を特に規定しないが、再現性よく評価する方法として、加工は圧延法、加熱は十分な熱容量を備えた熱風循環炉で行なうことが望ましい。
【００４０】
【実施例】
表１に示す化学成分の鋼を溶製し、加熱温度１２５０℃にて加熱し、仕上温度８９０℃、巻取温度６４０℃にて熱間圧延し、板厚１．８ｍｍの熱延板とした。これらの熱延板を塩酸酸洗した後、冷間圧延し、各冷延板を再結晶焼鈍した。さらに、８〜１８％の二次圧延を行い、板厚０．１８ｍｍとした後、電解クロメート処理を施すことによりＴＦＳとし、さらにＰＥＴ樹脂フィルムを加熱下でラミネートした。
【００４１】
これらの鋼板に相当歪み０．２の加工を圧延法で施し、ＪＩＳ−５号試験片とした後、熱風循環炉で２１０℃×３分の加熱処理を行い、引張り試験で引張り強度を測定した。また、この処理を施さない鋼板の引張り強度も合せて測定し、処理による強度上昇量ΔＴＳを求めた。
【００４２】
また、これらの鋼板を実験室的に薄肉化深絞りしごき加工し、一般的な陽圧缶よりも板厚を約８％低減した軽量缶を試作し、ドーム加工した後、実生産相当の加熱処理を施した缶体の耐圧強度を測定した。耐圧強度は一般的な陽圧缶において必要とされる基準値との差（測定値−基準値）で示した。
【００４３】
表２に結果を示す。
【００４４】
【表１】

【００４５】
【表２】

【００４６】
本発明例では、加熱処理による強度上昇量ΔＴＳが８０ＭＰａ以上あり、約８％軽量化した缶体においても、耐圧強度が所定の特性値要求を満足することがわかる。
【００４７】
【発明の効果】
本発明の薄肉化深絞りしごき缶用鋼板は、耐圧強度が極めて優れ、缶体を軽量化した場合でも十分な耐圧強度を維持できる。
【図面の簡単な説明】
【図１】相当歪み０．２の加工および２１０℃で３分の加熱処理を施した後の引張り強度の上昇量と耐圧強度の関係を示す図である。
【図２】相当歪み０．２の加工および２１０℃で３分の加熱処理を施した後の引張り強度の上昇量とＡｌ／Ｎの関係を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin film laminated steel sheet for a thinned deep-drawn ironing can excellent in pressure resistance.
[0002]
[Prior art]
Among steel beverage cans, DI (Drawn and Ironing) cans and thinned deep-drawn iron cans are used as positive pressure cans that circulate inside the cans in a positive pressure state. Conventionally, DI cans have been the mainstream, but it is thought that thin-walled deep-drawn iron cans will grow greatly in the future because of the advantage of less environmental impact in the can-making process.
[0003]
A resin film laminated steel plate is used for the thinned deep drawn ironing can. A double cold pressure (hereinafter referred to as DR) material initially containing 0.1% C was used for the original plate. Thereafter, as in Patent Document 1 and Patent Document 2, for example, a technique for reducing the weight of the can body by reducing the amount of C and improving the workability has been developed, thereby reducing the cost of the can body.
[0004]
In the future, further progress will be required in reducing the cost of thinned deep-drawn iron cans, and further weight reduction is being studied.
[0005]
On the other hand, in a positive pressure can in which a thinned deep-drawn iron can is used, there is a problem that the bottom of the can is cramped due to an increase in internal pressure. The internal pressure at the buckling limit is called pressure strength, which is governed by the shape of the bottom of the can and is known to depend on the thickness and strength of the steel sheet.
[0006]
Although the shape of the bottom of the can is processed into a dome shape that is strong against internal pressure, the current reduction in the thickness of deep-drawn ironing can steel plates is important for reducing weight and increasing the workability. In the case of proceeding with the above, a decrease in the pressure strength becomes a problem to be concerned in the future.
[0007]
As described above, in order to reduce costs by reducing the weight of thin-walled deep-drawn ironing cans, it is necessary to solve the problem of securing pressure resistance, but for thin-walled deep-drawn ironing cans that still have sufficient characteristics. Steel sheets are not presented.
[0008]
The prior art document information is described below.
[0009]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-34912
[Patent Document 2]
Japanese Patent Laid-Open No. 7-34194
[Problems to be solved by the invention]
In view of the current state of the prior art, the present invention aims to provide a steel plate for a thinned deep-drawn ironing can excellent in pressure strength.
[0012]
[Means for Solving the Problems]
The inventors of the present invention have made various studies on a steel plate for a thinned deep drawn ironing can excellent in pressure resistance. As a result, the inventors have found for the first time a steel sheet capable of achieving both weight reduction and pressure strength. That is, the gist of the present invention is as follows.
Steel component is mass%,
C: 0.01 to 0.06%,
Mn: 0.1 to 0.6%
Al: 0.01 to 0.10%,
N: 0.0010 to 0.0050%,
And ratio Al / N of content of Al and N expressed by mass% is 25 or less,
The balance Fe and inevitable impurities,
A cold-rolled steel sheet having a cold pressure twice laminated with an organic resin film,
A steel plate for a thinned deep-drawn ironing can excellent in pressure strength, in which the increase in tensile strength after performing processing of equivalent strain 0.2 and heating at 210 ° C. for 3 minutes in this order is 80 MPa or more.
[0013]
In addition, in this specification,% which shows a steel component is all the mass%.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
[0015]
The inventors of the present invention have studied a steel plate for a thin-walled deep-drawn ironing can that can achieve both weight reduction by reducing the plate thickness or increasing the workability and ensuring pressure resistance strength, and has led to the present invention. The idea can be explained as follows.
[0016]
Thin-walled deep-drawn iron cans are steel plates in which a resin film is laminated under heating to a tin-free steel plate (TFS) that has been recrystallized and annealed after cold rolling and then electrochromated on the surface of the secondary rolled DR material. Is used.
[0017]
The can manufacturing process is performed by a method combining thinning deep drawing, which reduces the thickness by bending and unbending at the shoulder of a small-diameter die while applying rear tension, and this is combined with ironing, and the bottom of the can is shaped like a dome. Then, heat treatment is performed for the purpose of removing the wax applied to the film surface and removing the processing distortion of the film.
[0018]
Dislocation due to new strain is introduced into the steel sheet by this dome processing, and the dome portion is strain-age-hardened by diffusing the solid solution elements in the steel sheet and fixing the dislocation by subsequent heat treatment. Since the pressure strength depends on the strength after such a series of can manufacturing processes, it is important to effectively use this strain age hardening in order to ensure the pressure strength.
[0019]
A DR material is used for the thinned deep drawn ironing can. In the DR material, many dislocations exist in the steel sheet, but since an organic resin film is laminated under heating, many solid solution elements are consumed for fixing the dislocations in this heating stage. There are C and N as solid solution elements that act on the fixation of dislocations. C, which diffuses faster than N, is a solid solution element that mainly fixes dislocations at this stage.
[0020]
In addition, when the can body is reduced in weight by reducing the thickness of the original plate or increasing the degree of processing, the heat capacity of the can body inevitably decreases, and the heat history during the heat treatment changes. In particular, in the heating stage where dislocation fixation due to diffusion of solid solution elements proceeds, the weight of the can that has been reduced in weight increases faster than before, and as a result, is maintained at a relatively high temperature. It has been found that the time taken to become longer.
[0021]
From the above, in the steel plate for thinned deep-drawn ironing cans using DR material, when strain age hardening is effectively used for securing pressure-resistant strength in a lightweight can body, It has been found that it is important to utilize the action of N effective for age hardening. That is, the inventors have come to the knowledge that the pressure strength can be effectively ensured by appropriately balancing the amounts of Al and N, which are important in the components of the present invention, and Al / N.
[0022]
Here, the reason why the increase in tensile strength after performing processing of equivalent strain 0.2 and heating at 210 ° C. for 3 minutes in this order was used as an index of pressure resistance will be described.
[0023]
In the dome processing part at the bottom of the can, the first cramped portion when the internal pressure of the can is raised is the root inside the grounding part. Since the portion is subjected to heat treatment after strain is introduced by dome processing, strain age hardening occurs, and the strength increases compared to the time of the flat plate before canning. That is, in order to ensure sufficient pressure resistance, it is necessary to pay attention to the amount of strength increase due to dome processing and heat treatment of the part. As a result of detailed investigation, it was found that the strain amount of the part corresponds to an equivalent strain of 0.2, and the strain age hardening amount by heat treatment can be reproduced by heating at 210 ° C. for 3 minutes.
[0024]
FIG. 1 shows that a steel plate for thinned deep-drawn iron cans with different amounts of Al and N is subjected to a process of equivalent strain 0.2 by rolling, processed into a JIS-5 tensile test piece, It is the figure which showed the raise amount of the tensile strength at the time of performing a tensile test after performing the heat processing for 1 minute, and the pressure-resistant strength of the thin-walled deep-drawn ironing can. Here, the pressure strength is indicated by a difference from the reference value (measured value−reference value). In addition, a lightweight can with a can thickness of about 8% less than that of a general positive pressure can is prototyped. As shown in FIG. 1, it can be seen that when the amount of increase in tensile strength is 80 MPa or more, even a prototype lightweight can can achieve a compressive strength greater than a reference value required for a general positive pressure can.
[0025]
FIG. 2 shows that a steel plate for thinned deep-drawn iron cans with different amounts of Al and N was subjected to processing with a corresponding strain of 0.2 by rolling, and this was processed into a JIS-5 tensile test piece, which was processed at 210 ° C. 3 It is a figure which shows the increase amount of the tensile strength at the time of performing a tensile test after performing the heat processing for 1 minute, and the relationship with Al / N. It can be seen that the increase in tensile strength of 80 MPa or more shown in FIG. 1 can be obtained by setting Al / N to 25 or less.
[0026]
Next, the reasons for limiting the steel components of the present invention will be described.
[0027]
C is an important element for adjusting the strength of the steel sheet. If it is less than 0.01%, the strength to be provided as a steel plate for a thinned deep-drawn ironing can cannot be ensured, and if it exceeds 0.06%, the steel plate becomes excessively hardened and the workability itself is impaired. It was set to 01% to 0.06%.
[0028]
Mn is added mainly for the purpose of adjusting the strength of the steel sheet and preventing hot brittleness. However, if it is less than 0.1%, the purpose cannot be achieved, and if it exceeds 0.6%, the steel sheet becomes excessively hard and cans are made. The workability itself is impaired. Therefore, it is set to 0.1 to 0.6%. From the viewpoint of the above action and component control, preferably 0.15 to 0.55% Al is added for the purpose of deoxidizing molten steel and fixing N, but in the present invention, it is an important element in relation to N It is. If the amount is less than 0.01%, the purpose is not sufficiently achieved. If the amount exceeds 0.10%, the effect is saturated and non-metallic inclusions are increased to cause surface scratches. Is 0.01 to 0.10%. From the viewpoint of the above action and component control, it is preferably 0.03 to 0.06%.
[0029]
N, together with Al, is an important element in the present invention. When N is less than 0.0010%, not only the strain age hardening that is the main focus of the present invention cannot be exhibited, but also the de-N treatment time in steelmaking is increased, and the risk of inclusion inclusion increases and the cost increases. This is not preferable in terms of economy. Moreover, since the intensity | strength of steel plate itself will rise excessively when it exceeds 0.0050%, the upper limit shall be 0.0050%. From the viewpoint of the above action and component control, it is preferably 0.0015 to 0.0030%.
[0030]
In the present invention, the quantitative relationship between Al and N is 25 or less in terms of Al / N. N precipitates as AlN in the hot rolling and annealing stages, but in this case, it is necessary that N that does not precipitate remains in order to exert strain age hardening by N in the heat treatment performed after the can manufacturing process. . By setting Al / N to 25 or less, an amount of N necessary for exhibiting strain age hardening remains in the heat treatment applied after the can manufacturing process, and as shown in FIG. Can be made 80 MPa or higher, so that the pressure resistance of the molded can can be made higher than the reference value.
[0031]
In addition to the above components, the steel contains Si, P, S, etc., but these components do not particularly affect the steel sheet characteristics of the present invention, and therefore may be appropriately included within a range that does not affect other characteristics. it can. In addition, elements other than those described above can be added within a range that does not adversely affect the characteristics.
[0032]
Next, the manufacturing method of the steel plate of this invention is demonstrated.
[0033]
The steelmaking conditions and the slab manufacturing conditions may be any method as long as the steel components specified in the present invention can be obtained, and are not particularly specified. However, the slab is manufactured by continuous casting because of the uniformity of the slab. It is desirable to do so. The heating condition of the slab is not particularly specified, but the heating temperature is preferably 1250 ° C. or higher in order to promote the remelting of nitride.
[0034]
Although the hot rolling conditions are not particularly specified, the finishing temperature is desirably 870 ° C. or higher from the uniformity, surface properties, and mechanical properties of the hot rolled steel sheet. The winding temperature is preferably 560 to 640 ° C. for the same reason.
[0035]
Although pickling, cold rolling, and recrystallization annealing conditions are not particularly defined, continuous annealing is desirable from the economical viewpoint.
[0036]
Although the secondary rolling conditions are not particularly defined, the rolling rate is preferably 5 to 20% from the viewpoints of steel sheet thickness control, mechanical properties, and anisotropy.
[0037]
Any surface treatment may be used as long as it is suitable as a base for laminating an organic resin film, but TFS or similar electrolytic chromate treatment is desirable from the viewpoint of corrosion resistance and film adhesion.
[0038]
The organic resin film and the lamination conditions are not particularly defined as long as they have the characteristics to be provided as a steel plate for a thin-walled deep-drawn ironing can. Lamination is preferably performed under heating.
[0039]
In addition, regarding the processing of equivalent strain 0.2 that characterizes the steel sheet characteristics of the present invention and the heat treatment at 210 ° C. for 3 minutes, the method of imparting is not particularly defined, but as a method for evaluating with good reproducibility, the processing is performed by rolling. It is desirable that the method and heating be performed in a hot air circulating furnace having a sufficient heat capacity.
[0040]
【Example】
Steels having the chemical components shown in Table 1 were melted, heated at a heating temperature of 1250 ° C., and hot-rolled at a finishing temperature of 890 ° C. and a winding temperature of 640 ° C. to obtain a hot-rolled sheet having a thickness of 1.8 mm. . These hot-rolled sheets were pickled with hydrochloric acid and then cold-rolled, and each cold-rolled sheet was recrystallized and annealed. Further, secondary rolling of 8 to 18% was performed to obtain a plate thickness of 0.18 mm, and then TFS was performed by performing an electrolytic chromate treatment. Further, a PET resin film was laminated under heating.
[0041]
These steel sheets were subjected to processing with an equivalent strain of 0.2 by a rolling method to obtain a JIS-5 test piece, followed by heat treatment at 210 ° C. for 3 minutes in a hot air circulating furnace, and the tensile strength was measured by a tensile test. . Further, the tensile strength of the steel sheet not subjected to this treatment was also measured and the strength increase ΔTS due to the treatment was obtained.
[0042]
In addition, these steel sheets are thinned and deep-drawn and ironed in the laboratory to produce a lightweight can with a thickness of about 8% less than that of a normal positive pressure can. The pressure resistance of the treated can was measured. The pressure strength was indicated by the difference (measured value−reference value) from the reference value required for a general positive pressure can.
[0043]
Table 2 shows the results.
[0044]
[Table 1]

[0045]
[Table 2]

[0046]
In the example of the present invention, it can be seen that the strength increase ΔTS due to the heat treatment is 80 MPa or more, and the pressure resistance satisfies the predetermined characteristic value requirement even in a can body that is about 8% lighter.
[0047]
【The invention's effect】
The thin-walled deep-drawn ironing can steel sheet according to the present invention has extremely high pressure strength, and can maintain sufficient pressure strength even when the can body is lightened.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the amount of increase in tensile strength and the pressure resistance after processing with an equivalent strain of 0.2 and heat treatment at 210 ° C. for 3 minutes.
FIG. 2 is a diagram showing the relationship between the amount of increase in tensile strength and Al / N after processing with an equivalent strain of 0.2 and heat treatment at 210 ° C. for 3 minutes.

Claims (1)

鋼成分が、質量％で、
Ｃ：０．０１〜０．０６％、
Ｍｎ：０．１〜０．６％、
Ａｌ：０．０１〜０．１０％、
Ｎ：０．００１０〜０．００５０％、
かつ、質量％で表したＡｌとＮの含有量の比Ａｌ／Ｎが２５以下、
残部Ｆｅおよび不可避的不純物からなり、
有機樹脂フィルムがラミネートされた二回冷圧の冷間圧延鋼板であって、相当歪み０．２の加工と２１０℃で３分の加熱をこの順で行なった後の引張り強度の上昇量が８０ＭＰａ以上である、耐圧強度に優れた薄肉化深絞りしごき缶用鋼板。Steel component is mass%,
C: 0.01 to 0.06%,
Mn: 0.1 to 0.6%
Al: 0.01 to 0.10%,
N: 0.0010 to 0.0050%,
And ratio Al / N of content of Al and N expressed by mass% is 25 or less,
The balance Fe and inevitable impurities,
A cold-rolled steel sheet with a double cold pressure laminated with an organic resin film, the amount of increase in tensile strength after performing processing of equivalent strain 0.2 and heating at 210 ° C. for 3 minutes in this order is 80 MPa. The above is a steel plate for thinned deep drawn ironing cans with excellent pressure strength.

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