JP3692797B2 - Steel plate for cans with good surface properties and excellent can stability - Google Patents

Description

【００５０】
一方、比較のために、転炉出鋼後、300 ton の溶鋼をRH真空脱ガス装置にて脱炭処理し、Ｃ＝0.014 wt％、Si＝0.01wt％、Mn＝0.25wt％、Ｐ＝0.010 wt％、Ｓ＝0.004 〜0.008 wt％に調整するとともに、Ｓ＝0.001 〜0.008 wt％に調整するとともに、溶鋼温度を1590℃に調整した。この溶鋼中に、Alを1.2 〜1.6kg/ton 添加し脱酸処理を行った。脱酸処理後の溶鋼中のAl濃度は0.035 wt％であった（Alキルド鋼）。その後、FeTiを添加するとともに、成分調整を行った。この処理の後のTi濃度は0.040 wt％であった。
【００５１】
次に、この溶鋼を２ストランドスラブ連続鋳造装置にて鋳造し連鋳スラブを製造した。なお、このときの、タンディッシュ内溶鋼の介在物の平均的な組成は、95〜98wt％Al₂O₃, 5％以下のTi₂O₃ のクラスター状の介在物が主体であった。
【００５２】
鋳造時にタンディッシュならびに浸漬ノズル内にArガスを吹き込まなかった場合には、著しくノズルにAl₂O₃ が付着し、３チャージ目にスライディングノズルの開度が著しく増加し、ノズル詰まりにより鋳込みを中止した。また、Arガスを吹いた場合にも、ノズル内にはAl₂O₃ が大量に付着しており、８チャージ目にはモールド内の湯面の変動が大きくなり鋳込みを中止した。
【００５３】
次に、上記連鋳スラブはスラブ加熱温度：1150℃、仕上圧延温度：890 ℃、巻取り温度：680 ℃で1.8 mmまで熱間圧延したのち、酸洗・冷延して板厚0.18mmの冷延板とした。その後、750 ℃で20 s均熱の連続焼鈍型の短時間焼鈍を行い、介在物の調査、成形性調査試験（破胴発生率試験）及び錆発生の調査を行った。この冷延鋼板にはヘゲ、スリーバー、スケールなどの非金属介在物性の欠陥は0.45個/1000m−コイル認められた。
【００５４】
得られた冷延板の破胴発生率試験の結果を、Ｓ− 5×（(32/40) Ca＋(32/140) REM) との関係で表１に示す。ここで、比較例１〜６は、Ｓ、Ca、REM の関係以外はこの発明に従い製造した鋼であり、比較例７は比較用に溶製したAlキルド鋼である。なお、この破胴発生率試験は、鋼板の潤滑条件を実製缶条件よりも悪い状態で絞り−再絞り−再々絞り成形を行い、割れを生ずる割合を比較するものである。なお成形の寸法は市販の350 ml缶サイズである。この発明が対象とする極薄の缶用鋼板では加工の限界を決定する要因の一つであり、より低い値が要求される。
【００５５】
表１より、この発明の鋼板の好適な方法で溶製し、かつ、Ｓ− 5×（(32/40) Ca＋(32/140) REM) が0.0014wt％以下の鋼板は、優れた、すなわち低い破胴発生率を示した。なお、鋼板の錆発生率（０℃、湿度95％中に10時間放置後）については、発明鋼、比較鋼とも問題のない値であった。
【００５６】
（実施例２）
表２に示す成分組成を含み、残部は実質的に鉄からなる鋼をこの発明の好適な方法に従い転炉で溶製し、この鋼スラブを表３に示す条件で熱間圧延、冷間圧延、連続焼鈍、そして調質圧延を行い、最終仕上板厚を0.17mmとした。ただし、比較例である鋼No. 14はこの通常のアルミキルド鋼の溶製法に従い溶製した。そして、表面処理層として金属クロム層とクロム酸化物層を施し表面処理鋼板とした。
【００５７】
【表２】

【００５８】
【表３】

【００５９】
このようにして得られたティンフリー鋼板の鋼板特性の調査を行った。これらの調査方法は以下のとおりである。なお、表４中の酸化物系介在物組成は粒径１〜50μm の介在物を調査し、平均値（介在物サイズによる重み付けはせず）をとった。本発明の成分組成範囲になる試料は、介在物の個数の50％以上がTi酸化物：20wt％以上90wt％以下、CaO ，REM 酸化物の１種又は２種の合計：10wt％以上40wt％以下、Al₂O₃ ：40％以下の範囲内になることを確認している。
(A) 金属組織評価
製品断面を研磨、エッチングをした後、光学顕微鏡により金属組織を観察し、結晶粒径の測定を行った。
(B) 製品板の引張特性
JIS 5号引張試験片を使用し、製品板の各種引張特性を調査した。なお、平均ｒ値及びΔｒは以下の式で求めた。
平均ｒ値＝（ｒ_L ＋ｒ_C ＋ 2ｒ_D ）／４
Δｒ＝（ｒ_L ＋ｒ_C − 2ｒ_D ）／２
で求めた。ただし、ｒ_L 、ｒ_C 、ｒ_D は、それぞれ圧延方向に対して0 度、90度、45度の方向のｒ値を示す。
なお、製缶後の耳発生率を低減するには、Δｒを±0.2 以内に収めることが必要である。
【００６０】
(c) 製缶性及び製缶後の評価
表面処理鋼板の両面に厚さ20μm 、融点230 ℃のポリエステルフィルムを熱接着することにより樹脂フィルム被覆鋼板を得た。この樹脂フィルム被覆鋼板に予めパーム油を塗布し、直径179 mmの円盤に打ち抜き、常法に従い、浅絞りカップに成形した。次いで、第１次の再絞り加工、第２次再絞り加工及びしごき工程で成形し、カップ径63mm、カップ高さ127 mmの深絞りカップを得た。製缶時の破胴発生率はこの時の破胴発生率を測定した。この後、常法に従ってボトム成形を行った後、パーム油を洗浄水で脱脂した。耳発生量はこの時の耳高さの平均値により評価した。その後、トリミングを行い、次いでネックイン加工を行った。製缶後の肌あれについては、特に肌あれが発生し易い同じタイプの缶と比較して、その優劣を比較評価した。このような方法で1000缶の製缶実験を行い、各種評価を行った。
【００６１】
これらの調査結果より、肌荒れの防止には、製品板の平均結晶粒径を10μm 以下とし、製缶後の耳発生率を低減するにはΔｒを±0.2 以内に収めることが必要であることも判明した。これらの結果を表４に示す。
【００６２】
【表４】

【００６３】
【発明の効果】
以上説明したように、この発明に係る極薄板厚の極低炭素冷延鋼板は、その製造にあたり、連続鋳造時に浸漬ノズルの閉塞を引き起こすことがなく、極めて安定した連続鋳造が可能であり、圧延鋼板の表面は非金属介在物に起因する表面欠陥がほとんど皆無で極めて清浄である。更に、板厚が薄いにも関わらず極めて厳しいプレス成形を行った際の広範囲な成形可能範囲と耐食性に優れた性質を有する鋼板として缶用などとしての広範な用途に用いることができる。[0001]
BACKGROUND OF THE INVENTION
This invention has a good surface property and is deeply drawn as a two-piece can, and is suitable for use as a deep cylinder by further redrawing once or more, with a plate thickness of about 0.2 mm or less. In more detail, it is related to the steel plate for cans, and more specifically, it is a main defect phenomenon that hinders stable manufacturability in actual production (from a flat blank to a deep cup shape by drawing, ironing, etc. Proposes a steel plate with excellent local deformability that can suppress as much as possible, which means that the body (wall) part breaks in the process, and generally causes serious troubles that greatly reduce productivity. It is something to try.
[0002]
[Prior art]
In press forming of thin steel sheets (deep drawing forming a cylindrical container), when various non-uniformities (for example, non-uniformity of lubrication, wrinkle holding force, etc.) occur in the forming process, Cracking may occur, making stable high-speed can-making work difficult. Such cracks become more serious as the can-making process becomes more efficient and faster. In order to cope with this crack, the steel plate for cans, which is a material, has the property that even if the above-mentioned non-uniformity occurs, it has a characteristic that it is plastically deformed with a margin and does not cause cracking, that is, local deformation. It is important to improve performance.
[0003]
Therefore, it is important to improve the local deformability of a steel sheet for an extremely thin two-piece can. In recent years, in particular, there is a strong desire to reduce the amount of material used per can by reducing the thickness of the material. For this reason, an integrated molding method called ironing and drawing called stretch draw molding is often used. However, since this forming method is extremely strict processing for the steel sheet, it is easy to break in the form of a broken cylinder. Therefore, the importance of a steel plate having excellent local deformability that does not break down even under the drawing deformation including ironing is increasing.
[0004]
In order to improve the local deformability, a method for lowering the melting point of inclusions by controlling the composition of the inclusions as disclosed in JP-A-63-192846, as disclosed in JP-A-2-220735. A method for controlling the precipitation of TiN and MnS by adjusting dissolved oxygen in various steels has been proposed. However, since the local deformability deteriorates due to the presence of MnS and the oxide in the steel that extend long in the rolling stage, it is still difficult to obtain sufficient deformability for such a processing form.
Moreover, in steel containing Ti, a streak-like pattern is produced on the surface after plating, and an appearance defect may be caused. In this regard, Japanese Patent Laid-Open No. 5-9549 discloses a method in which Ca is further added to change sulfide inclusions in steel to other complex inclusions. However, in this method, inclusions are CaO-Al₂O_ThreeThere was a problem that the system became a starting point of rust and the corrosion resistance deteriorated.
[0005]
[Problems to be solved by the invention]
This invention has been developed as a result of adding experiments, investigations, and studies to solve the above-mentioned problems of the prior art, has little rust, and there is almost no deterioration of deformability due to inclusions and precipitates. And it aims at proposing the steel plate for cans which is excellent in the stability of can making which there is almost no fall of the surface property by inclusions.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the inventors have controlled the composition of oxide inclusions remaining in the steel, thereby controlling the oxides and sulfides present in the steel. It was concluded that this is effective in improving the surface texture and workability of ultra-thin steel sheets, especially the local deformability. In other words, the formation of large cluster inclusions is suppressed to achieve fine dispersion into inclusions with a size of 50 μm or less, and the amount of MnS in the steel is reduced to reduce all oxides and sulfides in the steel. By making the material finer and making it non-ductile, which does not easily deform as long as it is rolled, it is possible to obtain properties that are extremely excellent in workability, especially local deformability, and clogging of the casting nozzle when manufacturing steel sheets It has been found that various problems such as rusting and surface property degradation can be solved.
[0007]
  The present invention is based on the above findings.
  That is, this invention
[Claim 1]
  C: 0.001 to 0.1 wt%,
  Si: 0.2 wt% or less,
  Mn: 0.05 to 1.0 wt%,
  P: 0.02 wt% or less,
  Ti: 0.015-0.04wt%,
  Al: 0.001 to 0.01 wt%
  N: 0.01 wt% or less and
  0.0005 ~ 0.01wt% in total of one or two of Ca and REM
In addition,
The content of one or two of S, Ca and REM
S-5 × ((32/40) Ca + (32/140) REM) ≦ 0.0014wt%
And the balance is the composition of Fe and inevitable impurities, andParticle size 1 50 μ m Of oxide inclusions Ti Oxide: 20wt %that's all 90wt %Less than, CaO , REM Sum of one or two oxides: 10wt %that's all 40wt %Less than, Al ₂ O _Three : 40wt %Less than( Ti Oxide, CaO , REM One or two oxides, Al ₂ O _Three The sum of 100wt % Or less)A steel plate for cans having a tensile strength of 450 MPa or less, a | Δr | of 0.2 or less, a plate thickness of 0.2 mm or less and good surface properties and excellent can stability; and
  C: 0.001 to 0.1 wt%,
  Si: 0.2 wt% or less,
  Mn: 0.05 to 1.0 wt%,
  P: 0.02 wt% or less,
  Ti: 0.015-0.04wt%,
  Al: 0.001 to 0.01 wt%
  N: 0.01 wt% or less and
  0.0005 ~ 0.01wt% in total of one or two of Ca and REM
Including, and
  Ni: 0.005 to 1.0 wt%,
  Cr: 0.005 to 1.0 wt%,
  Nb: 0.002 to 0.04 wt%,
1 type or 2 types or more, and
The content of one or two of S, Ca and REM
S-5 × ((32/40) Ca + (32/140) REM) ≦ 0.0014wt%
And the balance is the composition of Fe and inevitable impurities, andParticle size 1 50 μ m Of oxide inclusions Ti Oxide: 20wt %that's all 90wt %Less than, CaO , REM Sum of one or two oxides: 10wt %that's all 40wt %Less than, Al ₂ O _Three : 40wt %Less than( Ti Oxide, CaO , REM One or two oxides, Al ₂ O _Three The sum of 100wt % Or less)It is a steel plate for cans having a tensile strength of 450 MPa or less, | Δr | of 0.2 or less, and a plate thickness of 0.2 mm or less, excellent surface properties and excellent can stability.
[0008]
  In this invention, GroupIt is more preferable that the texture is composed of fine crystal grains having a particle size of 10 μm or less.
[0009]
In addition, although the steel plate for cans of this invention is mainly intended for the steel plate for cans used for two-piece cans (cans that are formed by integrally forming the trunk and the bottom and combining the lid with it). In particular, so-called DI cans (Drawn and Wall Ironed Can), DTR cans (Drawn and Thin Redrawn Can) combined with aggressive thinning process in the drawing-redrawing process, and ironing processing added to it It is particularly suitable for steel plates for cans using advanced technology.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the results of research on which the present invention was based will be described.
In this invention, the surface property is good by using a component composition that satisfies the condition that Al is 0.001 wt% or more and 0.01 wt% or less, Ti is 0.015 wt% or more, and S and / or REM is 0.0005 wt% or more. Therefore, the steel plate for cans is excellent in the stability of can manufacturing. At this time, the inclusion is Ti₂O_Three-Ca / REM oxide-Al₂O_Three-SiO₂If the Ca concentration in the inclusions is 40 wt% or less, the starting point of rust does not occur. When the amount of Al exceeds 0.01 wt%, inclusions are Al₂O_ThreeSince it is based on -CaO and / or REM oxides, the CaO concentration in inclusions is about 50 wt%, which becomes a starting point of rust and deteriorates the corrosion resistance.
[0011]
In order to improve local deformability under deformation with ironing in the two-piece can manufacturing process,
1) Do not coarsen the oxides in the steel,
2) Do not coarsen the sulfides in the steel;
3) Making crystal grains fine and uniform (in addition, uniform means not mixed grains).
is important. This is equivalent to the presence of large internal defects when oxides and sulfides in steel are coarsened, and deformation is concentrated on the can body part during processing that causes drawing deformation along with ironing. This is because if there are coarse inclusions in such a portion, a broken body is likely to occur from that portion.
[0012]
With respect to the oxide of 1) above, by satisfying the condition that Al is 0.001 wt% or more and 0.01 wt% or less, Ti is 0.015 wt% or more, and Ca and / or REM is 0.0005 wt% or more, the oxide Al₂O_ThreeIt changes from the main to Ti-based oxide, and since this Ti-based oxide has good wettability with molten steel and it is difficult to form clusters, Al₂O_ThreeIt does not become coarse like the inclusions of the main body.
[0013]
In addition, with respect to the sulfide 2), it is important to suppress MnS precipitated during solidification, and if MnS is present, it extends during rolling and promotes cracking during processing. For this solution, S in the steel is fixed (detoxified) by Ca and / or REM which forms a more stable sulfide. For this purpose, the S content, the Ca content, and the REM content are
S-5 x ((32/40) Ca + (32/140) REM)) ≤ 0.0014wt%
(In the formula, S represents the amount of S (wt%), Ca represents the amount of Ca (wt%), and REM represents the amount of REM (wt%).)
It came to the thought that it was necessary to satisfy the relationship. That is, in order to fix S by the formation of CaS and REM sulfide, the larger the amount of Ca and REM added, the better, and the lower limit is shown by the above inequality. That is, an experimental result was obtained that S in a harmful state needs to be 0.0014% or less.
[0014]
Furthermore, for the above-mentioned 3) grain refinement, it is important to set the grain size of the steel sheet to 10 μm or less. For this purpose, it is important to adjust the production conditions as well as the steel components.
[0015]
As a result of various studies based on the above experimental results, the inventors limited the present invention as follows.
Hereafter, the reason for limitation is shown about each component.
(C: 0.001 to 0.1 wt%)
The present invention relates to a steel plate for cans that performs deep drawing or other severe press forming, and the strength of the steel plate is preferably lower. Therefore, it is desirable to reduce C as much as possible because C strengthens the solution by solid solution, or refines and strengthens precipitation by carbide. Further, reducing the amount of C improves the r value (Rankford value), and thus is particularly effective in the application of the two-piece can targeted by the present invention. A preferable upper limit is 0.1 wt%, and 0.007 wt% is more preferable. However, when C is extremely small, the crystal grain size becomes coarse, and a rough skin phenomenon occurs at the time of molding, thereby reducing the moldability. Further, when the crystal grain size becomes coarse in this way, the secondary work brittleness resistance after deep drawing tends to deteriorate. From the above, the preferable lower limit is 0.001 wt%, and more preferably 0.0012 wt% or more.
[0016]
(Si: 0.2 wt% or less (excluding 0))
Si is a component effective for deoxidation during melting. However, if the amount is too large, the work hardening becomes remarkable, and the hot rollability and cold rollability are significantly lowered. In addition, since it is a harmful component in terms of product ductility, 0.2 wt% was set as the upper limit. Moreover, a preferable upper limit is 0.05 wt%, and it is more desirable if it is 0.02 wt% or less.
[0017]
(Mn: 0.05-1.0 wt%)
Mn, like Si, is effective for deoxidation during melting. It also has the effect of suppressing hot brittleness. In order to exert these desirable effects, addition of 0.05 wt% or more is generally desirable. On the other hand, the present invention relates to a steel sheet that is subjected to extremely severe forming for a two-piece can, and an improvement in ductility is desired. If Mn is 1.0 wt% or less, the decrease in ductility due to its inclusion is small. Therefore, the upper limit of Mn is 1.0 wt%. If it is 0.7 wt% or less, it is more desirable.
[0018]
(P: 0.02 wt% or less)
P is a component that lowers the corrosion resistance of the steel, and it is also desirable to reduce it as much as possible because it also acts as an embrittlement component in the secondary work brittleness of the cans after various deep-drawing moldings targeted by the present invention. If the added amount is 0.02 wt% or less, a level of secondary work embrittlement resistance having almost no problem can be achieved, and excellent deep drawability can be secured. If it is 0.01 wt% or less, it is more suitable. The lower limit is not particularly defined, and is determined by a balance between an increase in production cost necessary for dephosphorization and a characteristic improvement effect.
[0019]
(Ti: 0.015-0.04wt%)
Ti is an important component in the present invention, and Ti deoxidation forms fine oxide inclusions with a size of 50 μm or less, controls grain growth during cold rolling and annealing, and balances strength and elongation. Improve. Furthermore, since this fine oxide is also effective for miniaturization of a hot-rolled sheet, a {111} recrystallization texture develops after cold rolling-annealing and the r value is improved. In addition, by controlling the texture by applying such a mechanism, the in-plane anisotropy of the r value can be particularly improved. This is a steel plate for a two-piece can where the occurrence of earrings is a problem. Is extremely important. When the addition amount is less than 0.015 wt%, the addition effect, that is, the generation of the fine oxide amount is insufficient, and the texture and crystal grain size control cannot be sufficiently achieved. Therefore, it was limited to 0.015 wt% or more. However, when Ti is added in excess of 0.04 wt%, the resistance to deformation during hot rolling is significantly increased, and the cold rolling property, which is extremely important for ultra-thin steel sheets with large cold rolling, is remarkable. Since it falls, cold rolling becomes difficult. For these reasons, the amount of Ti added was set to 0.015 to 0.04 wt%.
[0020]
(Al: 0.001 to 0.01 wt%)
Al is a particularly important component in the present invention. When the Al content exceeds 0.01 wt%, Al deoxidation occurs, and a huge Al₂O_ThreeA large amount of clusters are formed, the surface properties are deteriorated, and fine oxides of 50 μm or less capable of controlling the grain growth property during cold rolling and annealing are reduced, so that the strength elongation balance is lowered. Furthermore, when the present invention is applied to a two-piece can, cracks in the can-making process due to enormous alumina (clusters) inevitably mixed therein become prominent. This significantly impairs the stability of the can making operation. From the above, the Al content was limited to 0.01 wt% or less. More importantly, if the Al content is higher than this, the inclusion composition is Al.₂O_Three-CaO and / or Al₂O_Three-REM It becomes an oxide system, becomes a starting point of rust, and deteriorates corrosion resistance. From this viewpoint, the upper limit of Al is 0.01 wt%. The lower limit of the Al amount is 0.001 wt% from the viewpoint of degassing and stabilizing the operation of continuous casting.
[0021]
(N: 0.01wt% or less (excluding 0))
Since N contributes as a solid solution strengthening component, when applied to extremely severe plastic working as in the present invention, it leads to a decrease in ductility, so it is desirable to reduce it as much as possible. The upper limit of 0.01 wt% can prevent the above problem from becoming obvious. A preferable lower limit value is not particularly limited, but is 0.001 wt% in consideration of an increase in manufacturing cost and a change in mechanical properties for preventing nitriding in each manufacturing process. Moreover, a preferable upper limit is 0.005 wt%, and if it is 0.003 wt% or less, it is more preferable.
[0022]
(Ca and / or metal REM: 0.0005 to 0.01 wt% in total)
Ca and metal REM (referring to rare earth elements such as La and Ce) are important components in the present invention, and one or two of Ca and REM must be added in an amount of 0.0005 wt% or more. That is, after deoxidizing Ti, one or two of Ca and REM are added so that the content becomes 0.0005 wt% or more, and the oxide composition in the molten steel is changed to Ti oxide: 20 wt% or more and 90 wt%. Or less, preferably 85 wt% or less, CaO and / or REM oxide: 5 wt% to 40 wt%, Al₂O_ThreeIs a low-melting oxide oxide inclusion with a content of 40 wt% or less. If it does so, the adhesion to the nozzle of the Ti oxide containing a base metal can be prevented effectively at the time of continuous casting, and clogging of a nozzle can be prevented. Furthermore, CaO and / or REM oxide is present in the steel as fine particles, and can contribute to the refinement of the hot rolled sheet. Moreover, this inclusion also contributes effectively to improving the mechanical properties of the steel sheet after cold rolling and annealing. For these reasons, one or two of Ca and REM are added in a total amount of 0.0005 wt% or more. However, if the added amount exceeds 0.01 wt%, the corrosion resistance of the steel plate is significantly reduced. As an application, it becomes extremely difficult. From the above, the range was 0.0005 to 0.01 wt%.
[0023]
(S-5 x ((32/40) Ca + (32/140) REM) ≤ 0.0014 wt%)
Since S is a harmful component to the workability of steel, it is desirable to reduce it as much as possible. However, excessive desulfurization treatment increases costs, so the upper limit is set to 0.01 wt% in consideration of this and the improvement effect of mechanical properties. A more preferred upper limit is 0.005 wt%.
Further, S can exist as various sulfides in steel, but when it exists as MnS-based inclusions, it significantly extends in the rolling direction during hot rolling, and particularly in the direction perpendicular to the rolling direction. Deteriorates mechanical properties. In other words, this leads to a decrease in workability targeted by the present invention, particularly local deformability.
In this respect, the addition of Ca and REM improves the morphology and non-ductility of the sulfide, and the improvement in local ductility, which is the main focus of the present invention, becomes significant. According to the investigation by the inventors, the addition of Ca and REM is not clear for reasons, but it is considered that harmless sulfides up to about 5 times S of these elements by atomic ratio become harmless sulfides. Therefore, if the harmful amount of S, that is, the value of S-5 × ((32/40) Ca + (32/140) REM) is sufficiently small, the secondary work brittleness resistance is not lowered by sulfide. According to the investigation, it was found that there is no problem if the harmful amount of S is 0.0014 wt% or less.
[0024]
(O: 0.010 wt% or less)
O is an unavoidable component and is not particularly limited. However, O is a component necessary to some extent to produce a fine oxide. However, if it exceeds 0.010 wt%, coarse Al₂O_ThreeIs produced, and the workability represented by deep drawability deteriorates, so 0.010 wt% was made the upper limit. In addition, a preferable upper limit is 0.007 wt%, and if it is 0.005 wt% or less, it is more desirable.
[0025]
(Ni: 0.005 to 1.0 wt%)
(Cr: 0.005 to 1.0 wt%)
  Ni and Cr are made by refining the structure without solid solution strengthening of the steel sheet, or by facilitating deformation in a high strain rate environment. It is possible to prevent the occurrence of problems such as. Therefore, in the present invention, one or more of Ni and Cr can be added as necessary. In both cases, the addition of 0.005 wt% or more exhibits a remarkable effect, and this effect is not offset even when added in combination. However, even if added in excess of 1.0 wt%, the effect tends to saturate, leading to a significant increase in manufacturing cost. In both cases, the upper limit was set to 1.0 wt%. From the viewpoint of stabilizing the material, the range of 0.01 to 0.5 wt% is more preferable.
[0026]
(Nb: 0.002 to 0.04 wt%)
Nb, as well as Ni and Cr, is extremely effective in reducing the grain size of steel sheets. Therefore, in this invention, Nb can be added as needed. A remarkable effect is exhibited by addition of 0.002 wt% or more. However, even if Nb is added in excess of 0.04 wt%, the effect tends to saturate, and since remarkable hardening of the material occurs, both hot rollability and cold rollability deteriorate. For this reason, the amount of Nb added is in the range of 0.002 to 0.04 wt%. From the viewpoint of stabilizing the material, 0.005 to 0.02 wt% is more preferable.
[0027]
In the steel satisfying the above component composition range, the oxide inclusions having a particle size of 1 to 50 μm are inclusions containing one or two of Ti oxide, CaO and REM oxide. Then it is important. The inclusion as such a deoxidation product contains one or two of Ti oxide and CaO, REM oxide, more specifically, Ti oxide-CaO and / or REM oxide-Al.₂O_Three-SiO₂Ti-based oxide inclusions cause little rust, almost no deterioration of deformability due to inclusions and precipitates, and no surface defects due to cluster-like inclusions. The steel plate for cans as expected in the present invention has no adhesion of oxide to the nozzle.
The reason why the oxide inclusions defined in the present invention are limited to those having a particle diameter of 1 to 50 μm is because inclusions in such a range can be regarded as inclusions generated by deoxidation, Inclusions with particle sizes greater than 50 μm are generally due to extraneous inclusions such as slag or mold powder. Al₂O_ThreeSome clusters are larger than this, but if the oxide composition of inclusions with a particle size of 50 μm or less satisfies the above requirements, a huge Al₂O_ThreeIt can be considered that the system cluster is also sufficiently reduced.
[0028]
  The composition of the oxide inclusions having a particle size of 1 to 50 μm is as follows: Ti oxide: 20 wt% or more and 90 wt% or less, total of one or two kinds of CaO and REM oxide: 10 wt% or more and 40 wt% or less, Al₂O_Three : 40wt% Or less (Ti oxide, CaO, REM oxide 1 or 2 types, Al₂O_Three The total is 100wt% Or less)The
[0029]
  When the inclusion Ti oxide is less than 20wt%, it is not Ti deoxidized steel but Al deoxidized steel.₂O_Three Nozzle clogging occurs due to increased concentration. In addition, as the CaO and REM oxide concentration increases, the rust resistance deteriorates.20wt %The following. On the other hand, when the Ti oxide concentration exceeds 90 wt%, the ratio of CaO and REM oxide decreases and nozzle clogging occurs. Therefore, the Ti oxide concentration is set to 20 wt% or more and 90 wt% or less. More preferably, it is 30 wt% or more and 80 wt% or less.
[0030]
Further, if the total of one or two of CaO and REM oxides in the inclusion is less than 10 wt%, the inclusion does not have a low melting point and causes the nozzle to be blocked as described above. On the other hand, if it exceeds 40 wt%, the inclusions will subsequently absorb S and change to water-solubility, which becomes the starting point of rust, thus reducing the corrosion resistance. A more preferable range is 20 to 40 wt%.
[0031]
In addition, Al in the inclusion₂O_ThreeWhen the content exceeds 40 wt%, not only the nozzle clogging occurs due to the high melting point composition, but also the inclusions are clustered, increasing non-metallic inclusion physical defects in the product plate. In addition, when Al is hardly contained in steel, Al in inclusions₂O_ThreeIs almost negligible.
[0032]
The oxide inclusions may contain oxides other than those listed above, and the amount of oxides other than those listed above is not particularly limited. , SiO₂Is preferably controlled to 30 wt% or less, and MnO is preferably controlled to 15 wt% or less. The reason for this is that if these amounts exceed the respective amounts, it cannot be said that the titanium killed steel is an object of the present invention, and under such a composition, there is no nozzle clogging even without adding Ca, and there is also a problem of rusting. This is because it disappears. Moreover, SiO in the inclusions₂In order to contain MnO, it is preferable to set the Si and Mn concentrations of the molten steel to Mn / Ti> 100 and Si / Ti> 50 in consideration of the oxide formation tendency. Cause deterioration of surface properties.
The steel plate of the present invention is a steel plate having a thickness of 0.2 mm or less. This is because a thicker steel plate can perform a sufficiently stable can making operation without using the method of the present invention.
[0033]
When the steel sheet according to the present invention has a structure composed of uniform and fine crystal grains having a crystal grain size of 10 μm or less, even in an ultra-thin steel sheet, such as a poor appearance due to surface roughness after forming, a decrease in elongation caused by this, etc. Problems can be avoided. Therefore, it is preferable to have a structure composed of uniform and fine crystal grains having a crystal grain size of 10 μm or less, and it is more preferable that the grain size be 7 μm or less. Such a structure can be obtained by adjusting the steel composition and hot rolling conditions (slab heating temperature, finishing temperature, etc. described later).
[0034]
The tensile strength is 450 MPa or less. This is because when it exceeds 450 MPa, stable molding becomes difficult due to generation of wrinkles or the like when making cans.
[0035]
Also, | Δr | is 0.2 or less. This | Δr | evaluates the in-plane anisotropy of the r value of the steel sheet, and corresponds to the occurrence of ears (earrings) in the can manufacturing process. The measurement of | Δr | is performed by a normal tensile method in the case of a material having sufficient elongation, but may be obtained by a resonance method defined in JIS when the elongation is insufficient. If | Δr | exceeds 0.2, the earrings become prominent, the plate thickness distribution of the other can body becomes uneven, which leads to a decrease in yield, and causes wrinkles in the subsequent neck-in process and cracks in the flange process. .
[0036]
Next, the manufacturing method of the steel of this invention is demonstrated.
In this invention, the reason why Ti as an adjustment component is Ti: 0.015 wt% or more is that if the Ti content is less than 0.015 wt%, the oxygen removal capacity is weak, the total oxygen concentration in the molten steel becomes high, elongation, drawing, etc. This is because the material characteristics deteriorate. In this case, it is conceivable to increase the concentration of Si and Mn to increase the deoxidizing power, but if Ti is less than 0.015 wt%, SiO₂Or a large amount of inclusions containing MnO causes hardening of the steel material and deterioration of plating properties. In order to prevent this, it is necessary to contain Ti so that (wt% Mn) / (wt% Ti) <100. In that case, the Ti oxide concentration in the inclusions is 20% or more.
[0037]
In producing the titanium killed steel sheet according to the present invention, first, the molten steel is deoxidized with a Ti-containing alloy such as FeTi, and oxide inclusions mainly composed of Ti oxide are generated in the steel. The inclusions are not in the form of large clusters as in the case of deoxidation with Al, but are mostly granular and ruptured with a size of about 1 to 50 μm. However, if the Al concentration exceeds 0.010 wt% at this time, huge Al₂O_ThreeA cluster is generated. Such Al₂O_ThreeEven if the Ti alloy is added to increase the Ti concentration, the cluster cannot be reduced and remains in the steel as cluster-like inclusions. Therefore, with respect to the steel sheet according to the present invention, it is preferable to first produce Ti oxide in the molten steel at the stage of production.
[0038]
Under the present invention, the yield of the Ti alloy is poor compared to the conventional method of deoxidizing with Al, and the inclusion composition adjusting alloy is expensive because it contains Ca and REM. For this reason, it is economically preferable to add such an alloy into the molten steel so that the amount of the alloy is as small as possible within the range in which the composition of inclusions can be controlled. In this sense, prior to the addition of a deoxidizer such as a Ti-containing alloy, pre-deoxidation is performed so that the dissolved oxygen concentration is 200 ppm or less in order to reduce dissolved oxygen in the molten steel and FeO and MnO in the slab. It is desirable to do. This preliminary deoxidation is preferably performed by stirring the molten steel in a vacuum, deoxidizing with a small amount of Al (the Al in the molten steel after deoxidation is 0.010 wt% or less), and adding Si, FeSi, Mn, or FeMn.
If deoxidation with Ti is performed immediately after preliminary deoxidation, a large number of inclusions that are insufficiently modified remain in the molten steel, making it difficult to control the target inclusion composition. Therefore, by stirring for 3 to 4 minutes after the addition of the predeoxidizer and 8 to 9 minutes after the addition of Ti, the inclusions are Ti oxide: 20 wt% or more and 90 wt% or less, one of CaO and REM oxide Or total of 2 types: 10wt% or more and 40wt% or less, Al₂O_Three: The composition is 40% or less and becomes an inclusion governed by Ti deoxidation.
[0039]
As mentioned above, Ti produced by Ti deoxidation₂O_ThreeSince ≧ 70% Ti oxide inclusions are dispersed in steel with a size of about 2 to 20 μm, surface defects due to cluster inclusions are eliminated. However, Ti oxide is in a solid state in molten steel, and ultra-low carbon steel has a high solidification temperature, so it grows on the inner surface of the tundish nozzle in the form of taking in the metal, and clogs the nozzle. Trigger.
[0040]
Therefore, in the steel sheet according to the present invention, after deoxidizing with a Ti alloy, either one or two of Ca and REM are further added so as to be 0.0005 wt% or more, and the grain size in the molten steel is 1 to 50 μm. Ti oxide: 20 wt% or more and 90 wt% or less, preferably 85 wt% or less, CaO and / or REM oxide: 5 wt% or more and 40 wt% or less, Al₂O_ThreeIs a low-melting oxide oxide inclusion with a content of 40 wt% or less. If it does so, it will become possible to prevent effectively adhesion to the nozzle of Ti oxide containing bullion. More preferable inclusions are Ti oxide: 30 wt% to 80 wt%, CaO 2 REM oxide (La₂O_Three, Ce₂O_ThreeEtc.): 10wt% or more and 40wt% or less, Al₂O_Three : 20% or less, other (SiO₂, MnO, etc.): 10% or less.
The composition of such oxide inclusions is measured by performing quantitative analysis on each inclusion using EPMA or a scanning electron microscope having an EDX function. Although it is most desirable that all the inclusions in the steel analyzed in this way satisfy the above composition, in practice, the number of inclusions having a size of 1 to 50 μm is 50% or more. Is within the above composition range, the various characteristics of the steel sheet aimed at by the present invention are achieved. In addition, the largest diameter in each grain shall be used for a particle size.
[0041]
In this invention, when the composition of the inclusions to be generated is controlled as described above, it is possible to completely prevent oxides and the like from adhering to the inner surface of the tundish nozzle and the immersion nozzle of the mold during continuous casting. Therefore, Ar and N are used to prevent adhesion of oxides in tundish and immersion nozzles.₂It is no longer necessary to blow in gas. As a result, it is possible to prevent the occurrence of powder defects in the slab due to powder entrainment during continuous casting and bubble defects due to the blown gas in the slab.
[0042]
Regarding the hot rolling process after continuous casting, the slab heating temperature is preferably 1000 to 1300 ° C. When the slab heating temperature is less than 1000 ° C., the load load particularly during rough rolling becomes too high, resulting in operational problems. On the other hand, a high temperature exceeding 1300 ° C. is not preferable because the crystal grain size before rolling becomes too large, and it becomes difficult to make the hot-rolled sheet uniform and fine, and the rough surface of the steel sheet for cans becomes remarkable. Therefore, the slab heating temperature was set to 1000 to 1300 ° C. Of these, a slab heating temperature of 1200 ° C. or lower is preferable from the viewpoint of deep drawability. Further, DHCR (direct hot charge rolling) in which a continuously cast slab is inserted into a heating furnace with a hot piece and direct feed rolling (CC-DR) are preferable from the viewpoint of energy saving.
[0043]
The hot rolling end temperature is preferably 850 to 960 ° C. This is because when the temperature is lower than 850 ° C., the structure of the hot-rolled base plate becomes non-uniform, which adversely affects even after cold rolling and annealing, and causes problems such as surface roughness after processing. Above 960 ° C, the risk of scale flaws increases.
The coil winding temperature after hot rolling is more advantageous for the coarsening of precipitates as the temperature is higher, but if it is too high, problems such as excessively thick scales occur, so 400 to 750 ° C. is preferable.
After hot rolling, pickling and cold rolling are performed before annealing.
Pickling does not require special conditions. That is, the surface oxide scale layer is removed with hydrochloric acid or sulfuric acid as is usually done.
[0044]
There are no special conditions for cold rolling, but since the product is thin, the cold rolling reduction is as high as 85% or more compared to a general cold-rolled steel sheet. A more preferable rolling reduction of cold rolling is 85 to 95%. If it exceeds 95%, the value of | Δr | becomes large and it becomes difficult to make | Δr |
In the annealing process, it is necessary to have a complete recrystallized structure in order to obtain a high degree of workability. For this reason, annealing is made more than the recrystallization temperature. The annealing method may be either continuous annealing or batch annealing, but continuous annealing is recommended from the viewpoint of efficiency and material uniformity.
In order to increase the strength and hardness of the steel sheet, secondary cold rolling can be performed after annealing. In this case, there is an advantage that the steel sheet can be thinned at the same time as increasing the strength.
[0045]
It is also possible to perform tin plating, nickel plating, tin-nickel plating, chrome plating, etc. on the steel plate produced as described above, and directly on or without these platings such as PET. It is also possible to laminate films.
The particle size of 10 μm or less can be achieved by combining these steel compositions and production conditions in an optimum range. For example, it is effective to combine many additions of Ti, Mn, etc., to lower the finish rolling finish temperature, coil winding temperature, and annealing temperature.
[0046]
【Example】
Example 1
After converter steelmaking, 300 ton molten steel was decarburized by RH degassing equipment, C = 0.014 wt%, Si = 0.01 wt%, Mn = 0.25 wt%, P = 0.010 wt%, S = 0.004 〜 While adjusting to 0.008 wt%, the molten steel temperature was adjusted to 1585-1615 ° C. In this molten steel, Al was added in an amount of 0.2 to 0.8 kg / ton, and preliminary deoxidation was performed for 3 to 4 minutes to reduce the dissolved oxygen concentration in the molten steel to 55 to 260 ppm. The Al concentration in the molten steel at this time was 0.001 to 0.005 wt%. And 70 wt% Ti-Fe alloy was added to this molten steel 0.8-1.8kg / ton, and Ti deoxidation was carried out over 8-9 minutes. Then, after adjusting the components, the molten steel contains 30wt% Ca-60wt% Si alloy, an additive mixed with metal Ca, Fe, 5-15wt% REM, or 90wt% Ca-5wt% Processing was performed by adding 0.05 to 0.5 kg / ton of Fe-coated wire of Ca alloy such as Ni alloy and REM alloy. After this treatment, the Ti concentration is 0.026 to 0.058 wt%, the Al concentration is 0.001 to 0.005 wt%, the Ca concentration is 0.0000 to 0.0034 wt%, the REM concentration is 0.0000 to 0.0020 wt%, and the sum of the Ca and REM concentrations is It was 0.0006-0.0043 wt%.
[0047]
Next, this steel was cast with a two-strand slab continuous casting apparatus to produce a continuous cast slab. Ar gas was not blown into the tundish and immersion nozzle during casting. As observed after continuous casting, there was almost no deposit in the tundish and the immersion nozzle.
[0048]
Next, the continuous cast slab was hot-rolled to a plate thickness of 1.7 mm. The hot rolling conditions were slab heating temperature: 1130 ° C, finish rolling temperature: 890 ° C, and hot rolling coiling temperature: 620 ° C. The hot-rolled steel sheet was pickled and cold-rolled to obtain a cold-rolled sheet having a thickness of 0.18 mm. After that, short-time annealing was performed in a continuous annealing type with a soaking temperature of 20 s at 740 ° C., and a fracture rate test and investigation of rust generation were conducted. Table 1 shows the results of the investigation on the steel composition and the fracture rate. At this time, most of the oxide inclusions had a width (maximum diameter) of 50 μm or less. The breakdown of oxide is Ti₂O_Three: 60-70%, CaO + REM oxide: 20-30%, Al₂O_Three: 15% or less. In this cold-rolled sheet, defects of non-metallic inclusion physical properties such as heges, slivers, and scales were found to be 0.00 to 0.02 pieces / 1000 m-coil or less.
[0049]
[Table 1]

[0050]
On the other hand, for comparison, 300 ton of molten steel was decarburized by RH vacuum degassing equipment after the converter steel, C = 0.014 wt%, Si = 0.01 wt%, Mn = 0.25 wt%, P = While adjusting to 0.010 wt% and S = 0.004 to 0.008 wt%, S was adjusted to 0.001 to 0.008 wt%, and the molten steel temperature was adjusted to 1590 ° C. The molten steel was deoxidized by adding 1.2 to 1.6 kg / ton of Al. The Al concentration in the molten steel after deoxidation treatment was 0.035 wt% (Al killed steel). Thereafter, FeTi was added and the components were adjusted. The Ti concentration after this treatment was 0.040 wt%.
[0051]
Next, this molten steel was cast with a two-strand slab continuous casting apparatus to produce a continuous cast slab. At this time, the average composition of inclusions in the molten steel in the tundish is 95 to 98 wt% Al.₂O_Three, Ti below 5%₂O_ThreeThe cluster-like inclusions were mainly.
[0052]
If Ar gas is not blown into the tundish and immersion nozzle during casting, the nozzle₂O_ThreeAttached, the opening of the sliding nozzle increased significantly at the third charge, and casting was stopped due to nozzle clogging. Even when Ar gas is blown, Al₂O_ThreeA large amount of was attached, and the fluctuation of the molten metal surface in the mold increased at the 8th charge, and casting was stopped.
[0053]
Next, the continuous cast slab was hot-rolled to 1.8 mm at a slab heating temperature of 1150 ° C, a finish rolling temperature of 890 ° C and a winding temperature of 680 ° C, and then pickled and cold-rolled to a thickness of 0.18 mm. Cold-rolled sheet was used. After that, short-time annealing was performed in a continuous annealing mold of 20 s soaking at 750 ° C. to investigate inclusions, formability investigation test (destructive rate test), and rust generation. This cold-rolled steel sheet was found to have defects of non-metallic inclusions such as heges, three bars, and scales of 0.45 / 1000 m-coil.
[0054]
Table 1 shows the results of the fracture rate test of the obtained cold-rolled sheet in relation to S-5 × ((32/40) Ca + (32/140) REM). Here, Comparative Examples 1 to 6 are steels manufactured according to the present invention except for the relationship of S, Ca, and REM, and Comparative Example 7 is Al killed steel melted for comparison. In this case, the ratio of occurrence of cracking is performed by performing drawing-redrawing-redrawing with the steel sheet lubrication conditions worse than the actual can conditions, and comparing the ratio of occurrence of cracks. The molding dimensions are those of a commercially available 350 ml can. The ultra-thin steel plate for cans targeted by the present invention is one of the factors that determine the processing limit, and a lower value is required.
[0055]
From Table 1, a steel plate having a S-5 × ((32/40) Ca + (32/140) REM) of 0.0014 wt% or less is excellent, ie, melted by a preferred method of the steel plate of the present invention, that is, It showed a low incidence of demolition. The rust generation rate of the steel sheet (after standing for 10 hours in 0 ° C. and 95% humidity) was a value with no problem for both the inventive steel and the comparative steel.
[0056]
(Example 2)
The steel composition comprising the composition shown in Table 2 and the balance being substantially iron is melted in a converter according to the preferred method of the present invention, and this steel slab is hot-rolled and cold-rolled under the conditions shown in Table 3. Then, continuous annealing and temper rolling were performed, and the final finished thickness was 0.17 mm. However, Steel No. 14, which is a comparative example, was melted in accordance with this ordinary aluminum killed steel melting method. And the metal chromium layer and the chromium oxide layer were given as a surface treatment layer, and it was set as the surface treatment steel plate.
[0057]
[Table 2]

[0058]
[Table 3]

[0059]
The steel plate characteristics of the tin-free steel plate thus obtained were investigated. These survey methods are as follows. The oxide inclusions in Table 4 were investigated for inclusions having a particle size of 1 to 50 μm and averaged (not weighted by inclusion size). In the sample within the composition range of the present invention, 50% or more of the number of inclusions is Ti oxide: 20 wt% or more and 90 wt% or less, and the total of one or two of CaO and REM oxide: 10 wt% or more and 40 wt% Hereafter, Al₂O_Three : Confirmed to be within the range of 40% or less.
(A) Metal structure evaluation
After polishing and etching the cross section of the product, the metal structure was observed with an optical microscope, and the crystal grain size was measured.
(B) Tensile properties of product plate
 JIS No. 5 tensile test pieces were used to investigate various tensile properties of product plates. The average r value and Δr were determined by the following formula.
Average r value = (r_L+ R_C+ 2r_D) / 4
Δr = (r_L+ R_C-2r_D) / 2
I asked for it. Where r_L, R_C, R_DIndicates r values in directions of 0 degrees, 90 degrees, and 45 degrees with respect to the rolling direction, respectively.
In order to reduce the incidence of ears after canning, it is necessary to keep Δr within ± 0.2.
[0060]
(c) Can-making ability and evaluation after can-making
A resin film-coated steel sheet was obtained by thermally bonding a polyester film having a thickness of 20 μm and a melting point of 230 ° C. to both surfaces of the surface-treated steel sheet. Palm oil was previously applied to the resin film-coated steel sheet, punched into a disk having a diameter of 179 mm, and formed into a shallow drawn cup according to a conventional method. Next, molding was performed by the first redrawing process, the second redrawing process, and the ironing process to obtain a deep drawn cup having a cup diameter of 63 mm and a cup height of 127 mm. The rate of occurrence of broken bodies during can making was measured at this time. Thereafter, bottom molding was performed according to a conventional method, and then palm oil was degreased with washing water. Ear generation amount was evaluated by the average value of ear height at this time. Thereafter, trimming was performed, and then neck-in processing was performed. The skin roughness after canning was evaluated by comparing its superiority and inferiority compared to the same type of cans that are particularly susceptible to skin roughness. In this way, 1000 cans were manufactured and evaluated in various ways.
[0061]
From these survey results, to prevent rough skin, it is necessary to keep the average crystal grain size of the product plate to 10 μm or less, and to reduce Δr within ± 0.2 in order to reduce the incidence of ears after canning. found. These results are shown in Table 4.
[0062]
[Table 4]

[0063]
【The invention's effect】
As explained above, the ultra-thin carbon cold-rolled steel sheet having an ultra-thin thickness according to the present invention is capable of extremely stable continuous casting without causing a clogging of the immersion nozzle during continuous casting. The surface of the steel sheet is extremely clean with almost no surface defects due to non-metallic inclusions. Furthermore, it can be used for a wide range of uses such as for cans as a steel plate having a wide range of formability and excellent corrosion resistance when extremely severe press forming is performed despite its thin plate thickness.

Claims (3)

C: 0.001 to 0.1 wt%,
Si: 0.2 wt% or less,
Mn: 0.05 to 1.0 wt%,
P: 0.02 wt% or less,
Ti: 0.015-0.04wt%,
Al: 0.001 to 0.01 wt%
N: 0.01 wt% or less and
0.0005 ~ 0.01wt% in total of one or two of Ca and REM
In addition,
The content of one or two of S, Ca and REM is the following formula S-5 × ((32/40) Ca + (32/140) REM) ≦ 0.0014wt%
The balance being the Fe and unavoidable impurities satisfies the relationship, and the particle size. 1 to 50 mu m oxide inclusions of Ti oxides: more than 20 wt% 90 wt% or less, CaO, of REM oxides Total of 1 type or 2 types: 10wt % or more and 40wt % or less, Al ₂ O ₃ : 40wt % or less ( Ti oxide, CaO , REM oxide, one or two, Al ₂ O ₃ Total has the following composition 100 wt%) of a tensile strength of 450 MPa or less, | [Delta] r | is 0.2 or less, a steel sheet for cans is surface texture plate thickness is less than 0.2 mm is excellent in the stability of good canning . C: 0.001 to 0.1 wt%,
Si: 0.2 wt% or less,
Mn: 0.05 to 1.0 wt%,
P: 0.02 wt% or less,
Ti: 0.015-0.04wt%,
Al: 0.001 to 0.01 wt%
N: 0.01 wt% or less and
0.0005 ~ 0.01wt% in total of one or two of Ca and REM
Including, and
Ni: 0.005 to 1.0 wt%,
Cr: 0.005 to 1.0 wt%,
Nb: 0.002 to 0.04 wt%,
1 type or 2 types or more, and
The content of one or two of S, Ca and REM is the following formula S-5 × ((32/40) Ca + (32/140) REM) ≦ 0.0014wt%
The balance being the Fe and unavoidable impurities satisfies the relationship, and the particle size. 1 to 50 mu m oxide inclusions of Ti oxides: more than 20 wt% 90 wt% or less, CaO, of REM oxides Total of 1 type or 2 types: 10wt % or more and 40wt % or less, Al ₂ O ₃ : 40wt % or less ( Ti oxide, CaO , REM oxide, one or two, Al ₂ O ₃ Total has the following composition 100 wt%) of a tensile strength of 450 MPa or less, | [Delta] r | is 0.2 or less, a steel sheet for cans is surface texture plate thickness is less than 0.2 mm is excellent in the stability of good canning . According to claim 1 or 2, a steel sheet for cans which the surface properties of the steel sheet is made of particle diameter 10 mu m or less of crystal grains is excellent in the stability of the good can manufacturing.