JP2006002203A - Cold rolled steel sheet with excellent deep drawability, and its manufacturing method - Google Patents
Cold rolled steel sheet with excellent deep drawability, and its manufacturing method Download PDFInfo
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本発明は、例えば自動車のパネル類、家電外板などに用いられる深絞り用冷延鋼板およびその製造方法に関するものである。本発明の冷延鋼板は、表面処理をしないものと、防錆のために溶融亜鉛めっき、電気めっきなどの表面処理を施したものの両方を含む。亜鉛めっきとは、純亜鉛のほか、主成分が亜鉛である合金のめっきも含む。本発明によれば深絞り性に優れた冷延鋼板を安価に得ることができるため地球環境保全に貢献しうるものと考えられる。 The present invention relates to a deep-drawn cold-rolled steel sheet used for, for example, automobile panels and home appliance outer panels, and a method for manufacturing the same. The cold-rolled steel sheet of the present invention includes both those not subjected to surface treatment and those subjected to surface treatment such as hot dip galvanization and electroplating for rust prevention. In addition to pure zinc, zinc plating includes plating of an alloy whose main component is zinc. According to the present invention, a cold-rolled steel sheet excellent in deep drawability can be obtained at low cost, and it is considered that it can contribute to global environmental conservation.
従来、冷延鋼板の深絞り性を向上させた鋼種として、第３版鉄鋼便覧第Ｉ巻基礎「日本鉄鋼協会編」丸善株式会社（昭和５８年３月３０日発行第４７６〜４８０頁（非特許文献１）に記載のようにＡｌキルド鋼やＴｉ添加極低炭素鋼などが開発されてきた。Ｔｉ添加極低炭素鋼では、Ｃ及びＮを析出物として完全に固定する程度のＴｉを添加しているため、深絞り性を阻害する要因である固溶Ｃ及び固溶Ｎはほとんど存在しない。一方、Ａｌキルド鋼は、Ａｌ窒化物の析出によって固溶Ｎを低減しているが、固溶Ｃは鋼中にある程度残存した状態にある。 Conventionally, as a steel grade that has improved the deep drawability of cold-rolled steel sheets, the third edition of the Steel Handbook Volume I Foundation “Japan Iron and Steel Institute” Maruzen Co., Ltd. (published March 30, 1983, pages 476-480 (non- Al killed steel, Ti-added ultra-low carbon steel, etc. have been developed as described in Patent Document 1) In Ti-added ultra-low carbon steel, Ti is added to the extent that C and N are completely fixed as precipitates. Therefore, there is almost no solid solution C or solid solution N, which is a factor that hinders deep drawability, while Al killed steel reduces solid solution N by precipitation of Al nitride. Molten C remains in the steel to some extent.
また、近年では、自動車の軽量化ニーズに伴い、鋼板の高強度化が望まれている。高強度化のために、固溶強化能を持ち安価な元素であるＣやＭｎを添加する手法が一般的に用いられる。但し、固溶ＣとＭｎがともに残存するような合金系では、深絞り性を向上させることが非常に困難である｛ＩＳＩＪ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｖｏｌ．３４（１９９４），Ｎｏ．１ ｐ８５−９１（非特許文献２）｝。 In recent years, it has been desired to increase the strength of steel sheets in accordance with the needs for weight reduction of automobiles. In order to increase the strength, a method of adding C or Mn, which is an inexpensive element having a solid solution strengthening ability, is generally used. However, it is very difficult to improve the deep drawability in an alloy system in which both solid solution C and Mn remain {ISI International Vol. 34 (1994), no. 1 p85-91 (nonpatent literature 2)}.
これに対して、固溶Ｃが残存し、Ｍｎ量が比較的多く、かつ深絞り性の良好な鋼板についても特公昭５７−４７７４６号公報（特許文献１）、特公昭５８−４９６２３号公報（特許文献２）等に開示されている。しかしながら、これらは箱焼鈍が前提となっており、連続焼鈍や連続溶融亜鉛めっきプロセスなどに比較すると生産性に劣る。また、Ｍｎを多量に含有している成分系において連続焼鈍工程における深絞り性向上方法については、特開２００３−６４４４３号公報（特許文献３）が公知である。しかしながら、深絞り性の指標を示すｒ値が１．３未満と低く、十分な深絞り性を有しているとは言いがたい。 On the other hand, steel plates with solid solution C remaining, a relatively large amount of Mn, and good deep drawability are disclosed in Japanese Patent Publication Nos. 57-47746 (Patent Document 1) and 58-96623 (Japanese Patent Publication No. 58-49623). Patent Document 2) and the like. However, these are premised on box annealing, and are inferior in productivity as compared with continuous annealing or continuous hot dip galvanizing process. Japanese Patent Laid-Open No. 2003-64443 (Patent Document 3) is known as a method for improving deep drawability in a continuous annealing process in a component system containing a large amount of Mn. However, the r value indicating the deep drawability index is as low as less than 1.3, and it cannot be said that the deep drawability is sufficient.
また、後述する本発明と重複するＣ、Ｍｏを含有する冷延鋼板として、特開２００３−２１３３６７号公報（特許文献４）が開示されている。しかし、特許文献４に開示されている発明は耐塩酸腐食及び耐硫酸腐食性に優れた鋼板であり、これらの効果を得るためＳｂを必須成分として含有し、深絞り性の向上を目的とした発明ではない。 Moreover, JP, 2003-213367, A (patent documents 4) is indicated as a cold-rolled steel plate containing C and Mo which overlap with the present invention mentioned below. However, the invention disclosed in Patent Document 4 is a steel plate excellent in hydrochloric acid corrosion resistance and sulfuric acid corrosion resistance, and in order to obtain these effects, it contains Sb as an essential component and aims to improve deep drawability. It is not an invention.
本発明は、固溶Ｃが残存するような鋼種において、Ｍｎを添加したときに深絞り性を劣化させることなく、成形性の良好な冷延鋼板及びその製造方法を提供することを目的とする。 An object of the present invention is to provide a cold-rolled steel sheet having good formability and a method for producing the same without degrading deep drawability when Mn is added in a steel type in which solute C remains. .
上記のような課題を解決すべく鋭意検討を進めたところ、固溶Ｃが残存している鋼種にＭｎを多量に添加しても深絞り性の良好な鋼板を得ることが可能であることを知見した。しかも、従来のような箱焼鈍プロセスに頼る必要もない。すなわち、添加Ｍｎ量に応じて定められる適正な量のＭｏを添加することにより、最終焼鈍を生産性の良い連続ラインで実施しても冷延焼鈍後の深絞り性を向上させることが可能であることを見出したものである。この理由は必ずしも明らかではないが、次のように考えられる。一般に固溶Ｃが残存している鋼種にＭｎを添加すると冷延後の焼鈍時にＭｎ−Ｃ相互作用により、回復及び再結晶が遅延し、深絞り性に好ましくない再結晶集合組織が形成される。これに対して、Ｍｏを添加すると固溶ＣとＭｏの相互作用により、前述のＭｎ−Ｃ相互作用が軽減され、再結晶集合組織への悪影響が低減されるためと考えられる。 As a result of diligent studies to solve the above problems, it is possible to obtain a steel sheet with good deep drawability even if a large amount of Mn is added to the steel type in which the solid solution C remains. I found out. Moreover, it is not necessary to rely on a conventional box annealing process. That is, by adding an appropriate amount of Mo determined according to the amount of added Mn, it is possible to improve the deep drawability after cold rolling annealing even if the final annealing is performed on a continuous line with good productivity. It has been found that there is. The reason for this is not necessarily clear, but is considered as follows. In general, when Mn is added to a steel type in which solid solution C remains, recovery and recrystallization are delayed by Mn-C interaction during annealing after cold rolling, and a recrystallized texture unfavorable for deep drawability is formed. . On the other hand, it is considered that when Mo is added, the above-described Mn—C interaction is reduced by the interaction between solute C and Mo, and the adverse effect on the recrystallization texture is reduced.
本発明の要旨とするところは、
（１）質量％で、Ｃ：０．００１０〜０．１０％、Ｓｉ：０．００１ 〜２．５％、Ｍｎ：０．０１〜３．０％、Ｐ：０．００１〜０．１５％、Ｓ：０．０３％以下、Ｎ：０．０００１〜０．０１０％、Ｍｏ：０．００５〜２．０％を含有し、Ａｌ、Ｔｉ，Ｎｂのうち１種または２種以上をＡｌ：０．００２〜０．１０％、Ｔｉ：０．００５〜０．１０％、Ｎｂ：０．００５〜０．１０％を満たすように含有し、（１）式及び（２）式を満足し、残部が鉄及び不可避的不純物からなることを特徴とする深絞り性に優れた冷延鋼板。
０．３≦Ｍｏ／Ｍｎ≦０．７・・・（１）、０．００１０≦Ｃ−１２×（Ｔｉ／４８＋Ｎｂ／９６−Ｎ'／１４）≦０．０８０・・・（２）
ここでＮ'は、Ｎ≧１４／２７×Ａｌの場合は、Ｎ−１４／２７×Ａｌで計算される値、Ｎ＜１４／２７×Ａｌの場合は０とする。
The gist of the present invention is that
(1) By mass%, C: 0.0010 to 0.10%, Si: 0.001 to 2.5%, Mn: 0.01 to 3.0%, P: 0.001 to 0.15% , S: 0.03% or less, N: 0.0001 to 0.010%, Mo: 0.005 to 2.0%, and one or more of Al, Ti and Nb: Al: 0.002 to 0.10%, Ti: 0.005 to 0.10%, Nb: 0.005 to 0.10%, satisfying the formula (1) and (2), A cold-rolled steel sheet excellent in deep drawability, wherein the balance is made of iron and inevitable impurities.
0.3 ≦ Mo / Mn ≦ 0.7 (1), 0.0010 ≦ C−12 × (Ti / 48 + Nb / 96−N ′ / 14) ≦ 0.080 (2)
Here, N ′ is a value calculated by N-14 / 27 × Al when N ≧ 14/27 × Al, and is 0 when N <14/27 × Al.
（２）Ｂを０．０００３〜０．０１０質量％含むことを特徴とする前記（１）に記載の深絞り性に優れた冷延鋼板。
（３）Ｚｒ、ＣｅおよびＭｇの１種または２種以上を合計で０．０００１〜０．５質量％含むことを特徴とする前記（１）又は（２）に記載の深絞り性に優れた冷延鋼板。
（４）Ｓｎ、Ｃｒ、Ｃｕ、Ｎｉ、ＣｏおよびＷの１種又は２種以上を合計で０．００１〜２．５質量％含むことを特徴とする前記（１）〜（３）のいずれか１項に記載の深絞り性に優れた冷延鋼板。
(2) The cold-rolled steel sheet having excellent deep drawability as described in (1) above, containing B in an amount of 0.0003 to 0.010 mass%.
(3) Excellent in deep drawability as described in (1) or (2) above, wherein one or more of Zr, Ce and Mg are contained in a total amount of 0.0001 to 0.5% by mass Cold rolled steel sheet.
(4) Any one of the above (1) to (3) characterized by containing 0.001 to 2.5 mass% in total of one or more of Sn, Cr, Cu, Ni, Co and W A cold-rolled steel sheet excellent in deep drawability according to item 1.
（５）Ｃａを０．０００１〜０．０１質量％以下含むことを特徴とする前記（１）〜（４）のいずれか１項に記載の加工性の優れた鋼板。
（６）前記（１）〜（５）の何れか１項に記載の鋼板を製造する方法であって、（１）〜（４）のいずれか１項に記載の化学成分を有する鋼を（Ａｒ3 −５０）℃以上で熱間圧延を完了し、熱延仕上げ温度から５５０℃までを平均冷却速度３０℃／ｓ以上で冷却し、５５０℃以下の温度で巻き取った後、圧延率６０〜９０％の冷間圧延及び焼鈍を施すことを特徴する深絞り性に優れた冷延鋼板の製造方法。
（７）焼鈍に引き続き亜鉛めっきを施すことを特徴とする前記（６）記載の深絞り性に優れた冷延鋼板の製造方法にある。
(5) The steel sheet having excellent workability according to any one of (1) to (4), wherein Ca is contained in an amount of 0.0001 to 0.01% by mass or less.
(6) A method for producing the steel sheet according to any one of (1) to (5) above, wherein the steel having the chemical component according to any one of (1) to (4) is ( Ar 3 −50) Hot rolling is completed at a temperature higher than 50 ° C., the hot rolling finish temperature to 550 ° C. is cooled at an average cooling rate of 30 ° C./s or higher, and wound at a temperature of 550 ° C. or lower. A method for producing a cold-rolled steel sheet excellent in deep drawability, characterized by subjecting to ~ 90% cold rolling and annealing.
(7) The method for producing a cold-rolled steel sheet having excellent deep drawability according to (6), wherein galvanization is performed subsequent to annealing.
本発明は、深絞り性に優れた冷延鋼板及びその製造方法を提供するものであり、地球環境保全などに貢献するものである。 The present invention provides a cold-rolled steel sheet excellent in deep drawability and a method for producing the same, and contributes to global environmental conservation and the like.
以下に本発明を詳細に説明する。
Ｃ：高強度化やＢＨ性確保のために有効な元素であるが、深絞り性を劣化させるので上限は０．１０％とする。また、下限は精錬コストの著しい増加を招かないレベルである０．００１０％とした。製鋼工程における安定製造性を考慮したときに好ましい範囲は０．００１０〜０．０３０％である。さらに好ましくは０．００１０〜０．０１０％である。
The present invention is described in detail below.
C: An element effective for increasing the strength and securing the BH property, but the upper limit is set to 0.10% because the deep drawability is deteriorated. The lower limit was set to 0.0010%, which is a level that does not cause a significant increase in refining costs. When considering the stable productivity in the steelmaking process, the preferred range is 0.0010 to 0.030%. More preferably, it is 0.0010 to 0.010%.
Ｓｉ：安価に機械的強度を高めることが可能であり、要求される強度レベルに応じて添加する。一方で、過剰の添加はメッキのぬれ性や加工性の劣化を招くため、２．５質量％を上限とする。下限を０．００１％としたのは、これ未満とするのが製鋼技術上困難なためである。
Ｍｎ：高強度化に有効であるため、０．０１％以上の添加が必要である。過度の低下は熱間加工性の低下による製造コストの増加を招くため、上限は３．０％とする。製造安定性の点で好ましい範囲は０．１０〜２．３％である。
Si: It is possible to increase the mechanical strength at low cost, and it is added according to the required strength level. On the other hand, since excessive addition causes deterioration of the wettability and workability of plating, the upper limit is set to 2.5% by mass. The reason why the lower limit is set to 0.001% is that it is difficult to make it lower than this in terms of steelmaking technology.
Mn: Effective for increasing the strength, addition of 0.01% or more is necessary. Since an excessive decrease leads to an increase in manufacturing cost due to a decrease in hot workability, the upper limit is made 3.0%. A preferable range in terms of production stability is 0.10 to 2.3%.
Ｐ：高強度化に有効な元素であるので０．００１質量％以上添加する。０．１５質量％超を添加すると溶接性や溶接部の疲労強度、さらには、耐２次加工脆性が劣化するのでこれを上限とする。好ましくは０．０６質量％が上限である。また、特に良好な溶接部疲労特性が求められる場合には０．０１５％が上限となる。
Ｓ：不純物であり、低いほど好ましく、熱間割れを防止するために０．０３％以下とする。好ましくは０．０１５質量％以下である。また、Ｍｎ量との関係において、Ｍｎ／Ｓ＞１０であることが好ましい。
P: 0.001% by mass or more is added because it is an element effective for increasing the strength. If more than 0.15% by mass is added, the weldability, fatigue strength of the welded portion, and secondary work brittleness resistance deteriorate, so this is the upper limit. The upper limit is preferably 0.06% by mass. Further, when particularly good weld fatigue properties are required, 0.015% is the upper limit.
S: Impurity, preferably as low as possible, and 0.03% or less to prevent hot cracking. Preferably it is 0.015 mass% or less. Further, in relation to the amount of Mn, it is preferable that Mn / S> 10.
Ｎ：固溶状態で存在すると強度を増加させ、延性を低下する場合があるため、上限は０．０１０質量％とする。また、Ｎを０．０００１％未満とするには製鋼コストの大幅な増加を招くためこれを下限とする。０．０００５〜０．００５０質量％が深絞り性及び安定製造性に対してより好ましい範囲である。
Ｍｏ：Ｍｏは本発明において重要な役割を果たす元素である。Ｍｏによる深絞り性向上効果が発揮されるのは０．００５％以上であるため、これを下限とする。また、過剰に添加すると材料強度の増加によって延性を劣化させたり、焼鈍温度の高温化を招いて製造コストの増加をもたらすため、上限を２．０％とした。
N: When present in a solid solution state, the strength is increased and the ductility may be lowered. Therefore, the upper limit is 0.010% by mass. Further, if N is less than 0.0001%, the steelmaking cost is significantly increased, so this is set as the lower limit. 0.0005-0.0050 mass% is a more preferable range with respect to deep drawability and stable manufacturability.
Mo: Mo is an element that plays an important role in the present invention. Since the effect of improving deep drawability by Mo is 0.005% or more, this is the lower limit. Further, if added excessively, the ductility is deteriorated due to an increase in material strength, or the annealing temperature is increased and the manufacturing cost is increased, so the upper limit was made 2.0%.
Ａｌ、Ｔｉ，Ｎｂのうち１種または２種以上をＡｌ：０．００２〜０．１０％、Ｔｉ：０．００５〜０．１０％、Ｎｂ：０．００５〜０．１０％の範囲で添加する。これらの下限は、添加した際に深絞り性向上効果を発揮するのに必要な量を下限とした。また、上限は添加した際に大幅なコスト増加および延性等の成形性低下を招かないレベルとして定めた。 One or more of Al, Ti and Nb are added in the range of Al: 0.002 to 0.10%, Ti: 0.005 to 0.10%, Nb: 0.005 to 0.10% To do. The lower limit of these was the amount necessary to exhibit the deep drawability improving effect when added. Moreover, the upper limit was determined as a level that would not cause a significant increase in cost and a decrease in moldability such as ductility when added.
Ｍｏ量とＭｎ量の比は、下記（１）式を満足する必要がある。これを満足しない場合には良好な深絞り性が得られない。
０．３≦Ｍｏ／Ｍｎ≦０．７・・・（１）
また、下記（２）式を満足する必要がある。（Ｃ−１２）×（Ｔｉ／４８＋Ｎｂ／９６−Ｎ'／１４）で計算される値が、０．００１０未満であるとＭｏによる深絞り性向上効果が十分に発揮されず、また、０．０８０％超であると深絞り性を示すｒ値が著しく低くなる傾向にある。このために、０．００１０〜０．０８０％の範囲とした。製造性を考慮した場合には、０．００１０〜０．０３０％が好ましい。さらに好ましくは０．００１０〜０．００５０％である。
０．００１０≦Ｃ−１２×（Ｔｉ／４８＋Ｎｂ／９６−Ｎ'／１４）≦０．０８０・・（２）
（ここでＮ'は、Ｎ≧１４／２７×Ａｌの場合は、Ｎ−１４／２７×Ａｌで計算される値、Ｎ＜１４／２７×Ａｌの場合は０とする。）
The ratio of the Mo amount and the Mn amount needs to satisfy the following formula (1). If this is not satisfied, good deep drawability cannot be obtained.
0.3 ≦ Mo / Mn ≦ 0.7 (1)
Moreover, it is necessary to satisfy the following formula (2). When the value calculated by (C-12) × (Ti / 48 + Nb / 96-N ′ / 14) is less than 0.0010, the effect of improving deep drawability by Mo is not sufficiently exhibited. If it exceeds 080%, the r value indicating the deep drawability tends to be extremely low. For this reason, it was set as 0.0010 to 0.080% of range. In consideration of manufacturability, 0.0010 to 0.030% is preferable. More preferably, it is 0.0010 to 0.0050%.
0.0010 ≦ C−12 × (Ti / 48 + Nb / 96−N ′ / 14) ≦ 0.080 (2)
(Here, N ′ is a value calculated as N-14 / 27 × Al when N ≧ 14/27 × Al, and 0 when N <14/27 × Al.)
Ｂ：Ｂは加工性及び二次加工性向上に有効な元素であり、必要に応じて添加される。二次加工性向上効果が発揮されるのは、０．０００３％以上添加した場合であるのでこれを下限とする。また、過度に添加すると加工性を低下させたり、また、再結晶温度の高温化を招いたりするため、上限を０．０１０質量％とする。好ましくは０．０００４〜０．００３５質量％である。 B: B is an element effective for improving workability and secondary workability, and is added as necessary. The secondary workability improvement effect is exhibited when 0.0003% or more is added, so this is the lower limit. Moreover, since processability will fall when it adds excessively and the recrystallization temperature will be raised, an upper limit shall be 0.010 mass%. Preferably it is 0.0004-0.0035 mass%.
Ｚｒ，Ｃｅ及びＭｇは脱酸元素として有効である。一方、過剰の添加は酸化物、硫化物や窒化物の多量の晶出や析出を招き清浄度が劣化して、延性を低下させてしまう上、メッキ性を損なう。したがって、必要に応じてこれらの１種または２種以上を合計で質量％で０．０００１〜０．５０％添加する。 Zr, Ce and Mg are effective as deoxidizing elements. On the other hand, excessive addition causes a large amount of crystallization and precipitation of oxides, sulfides and nitrides, which deteriorates cleanliness and lowers ductility and impairs plating properties. Therefore, if necessary, one or more of these are added in a total of 0.0001 to 0.50% by mass.
Ｓｎ、Ｃｒ、Ｃｕ、Ｎｉ、Ｃｏ、Ｗは強化元素であり必要に応じてこれらの１種又は２種以上を合計で必要に応じて質量％で０．００１％以上添加する。過剰の添加は、コストアップや延性の低下を招くことから、２．５％以下とした。
Ｃａ：介在物制御のほか脱酸に有効な元素で、適量の添加は熱間加工性を向上させるが、過剰の添加は逆に熱間脆化を助長させるため、必要に応じて質量％で０．０００１〜０．０１％の範囲とする。
また、不可避的不純物として、Ｏ、Ｚｎ、Ｐｂ、Ａｓ、Ｓｂなどをそれぞれ０．０２質量％以下の範囲で含んでも、本発明の効果を失するものではない。
Sn, Cr, Cu, Ni, Co, and W are strengthening elements, and if necessary, one or more of these are added in a total amount of 0.001% or more as required. Excessive addition causes an increase in cost and a decrease in ductility, so the content was made 2.5% or less.
Ca: An element effective for inclusion control as well as deoxidation. Addition of an appropriate amount improves hot workability, but excessive addition conversely promotes hot embrittlement. The range is 0.0001 to 0.01%.
Moreover, even if it contains O, Zn, Pb, As, Sb, etc. in the range of 0.02 mass% or less as an unavoidable impurity, the effect of this invention is not lost.
製造にあたっては、高炉、転炉、電炉等による溶製に続き各種の２次製錬を行いインゴット鋳造や連続鋳造を行い、連続鋳造の場合には室温付近まで冷却することなく熱間圧延するＣＣ−ＤＲなどの製造方法を組み合わせて製造してもかまわない。鋳造インゴットや鋳造スラブを再加熱して熱間圧延を行っても良いのは言うまでもない。熱間圧延の加熱温度は特に限定するものではないが、後述する仕上げ温度を確保するためには１１００℃以上とすることが好ましい。 In production, CC is smelted in a blast furnace, converter, electric furnace, etc., followed by various secondary smelting, ingot casting and continuous casting, and in the case of continuous casting, hot rolling without cooling to near room temperature. -Manufacturing methods such as DR may be combined. Needless to say, the cast ingot or cast slab may be reheated for hot rolling. The heating temperature for hot rolling is not particularly limited, but is preferably 1100 ° C. or higher in order to ensure the finishing temperature described later.
熱延の仕上げ温度は（Ａｒ3 −５０）℃以上で行う。好ましくはＡｒ3 変態温度以上である。熱延仕上げ温度がこれよりも低いと熱延組織が混粒組織となりやすい。熱延後の冷却速度は熱延仕上げ温度から５５０℃までを平均冷却速度３０℃／ｓ以上で冷却する。このことによって熱延組織の結晶粒径を微細化できるため、焼鈍後の集合組織を深絞り性に有利な組織とすることが出来る。 The hot rolling finish temperature is (Ar 3 -50) ° C. or higher. Preferably is Ar 3 transformation temperature or more. If the hot rolling finish temperature is lower than this, the hot rolled structure tends to be a mixed grain structure. The cooling rate after hot rolling is from the hot rolling finishing temperature to 550 ° C. at an average cooling rate of 30 ° C./s or more. As a result, the crystal grain size of the hot-rolled structure can be refined, so that the texture after annealing can be made a structure advantageous for deep drawability.
巻き取り温度は５５０℃以下とする。好ましくは４００℃以下である。熱間圧延の１パス以上について潤滑を施しても良い。また、粗圧延バーを互いに接合し、連続的に仕上げ熱延を行っても良い。粗圧延バーは一度巻き取って再度巻き戻してから仕上げ熱延に供してもかまわない。熱間圧延後は酸洗することが望ましい。熱延後の冷間圧延における圧下率は６０〜９０％とする。冷延率が６０％未満又は９０％超であると十分な深絞り性が得られなくなるので、６０〜９０％に限定する。 The winding temperature is 550 ° C. or lower. Preferably it is 400 degrees C or less. Lubrication may be performed for one or more passes of hot rolling. Alternatively, the rough rolling bars may be joined to each other and finish hot rolled continuously. The rough rolled bar may be wound once and then rewound again before being subjected to finish hot rolling. It is desirable to pickle after hot rolling. The rolling reduction in cold rolling after hot rolling is 60 to 90%. If the cold rolling rate is less than 60% or more than 90%, sufficient deep drawability cannot be obtained, so it is limited to 60 to 90%.
焼鈍温度は再結晶温度以上１０００℃以下とすることが好ましい。本発明における再結晶温度とは、１０ｓの保定を伴う連続焼鈍ラインにて焼鈍を実施した際に再結晶が開始する温度を示す。焼鈍温度が再結晶温度未満であると良好な集合組織が発達しにくい。また、連続焼鈍や連続溶融亜鉛めっき工程にて焼鈍する場合には焼鈍温度を１０００℃以上とするとヒートバックル等を誘発し板破断などの原因となるのでこれを上限とすることが好ましい。 The annealing temperature is preferably not less than the recrystallization temperature and not more than 1000 ° C. The recrystallization temperature in the present invention refers to a temperature at which recrystallization starts when annealing is performed in a continuous annealing line with 10 s retention. When the annealing temperature is lower than the recrystallization temperature, a good texture is difficult to develop. In addition, when annealing is performed in a continuous annealing or continuous hot dip galvanizing process, if the annealing temperature is set to 1000 ° C. or higher, a heat buckle or the like is induced, which causes a plate breakage or the like.
焼鈍後にベイナイト、オーステナイト、マルテンサイトの第２相を得たい場合には、焼鈍温度をα＋γ２相領域またはγ単相域にて加熱し、それぞれの相を得るのに適した冷却速度と過時効条件、溶融亜鉛めっきを施す場合にはめっき浴温度や引き続く合金化温度を選択する必要があることは言うまでもない。なお、本発明では、焼鈍は連続ラインに限定しており、箱焼鈍は含まない。 To obtain the second phase of bainite, austenite, and martensite after annealing, heat the annealing temperature in the α + γ2 phase region or γ single phase region, and the cooling rate and overaging conditions suitable for obtaining each phase Needless to say, when hot dip galvanizing is performed, it is necessary to select a plating bath temperature and a subsequent alloying temperature. In the present invention, annealing is limited to a continuous line, and box annealing is not included.
焼鈍の後、亜鉛を主体とするめっきを施しても構わない。亜鉛めっきは連続溶融亜鉛めっきラインで焼鈍とめっきを連続で行うことが好ましい。溶融亜鉛めっき浴に浸漬の後、加熱して亜鉛めっきと地鉄との合金化を促す処理を行っても良い。また、溶融亜鉛めっきのほか、亜鉛を主体とする種々の電気めっきを行っても良いことは言うまでもない。
焼鈍後や亜鉛めっき後のスキンパスは形状強制や強度調整、さらには常温非時効性を確保する観点から必要に応じて行う。０．３〜５．０％が好ましい圧下率である。
After annealing, plating mainly composed of zinc may be performed. In galvanization, it is preferable to perform annealing and plating continuously in a continuous hot dip galvanizing line. After immersing in a hot dip galvanizing bath, a heat treatment may be performed to promote alloying of galvanizing and ground iron. In addition to hot dip galvanization, it goes without saying that various electroplating operations mainly composed of zinc may be performed.
Skin pass after annealing or galvanization is performed as necessary from the viewpoint of shape forcing, strength adjustment, and securing non-aging at room temperature. A preferable rolling reduction is 0.3 to 5.0%.
表１に示す成分の各鋼を溶製して１２５０℃に加熱後、仕上げ温度をＡｒ3 変態温度以上とする熱間圧延を行い、冷却後、巻き取った。さらに冷延、次いで焼鈍を行った。各種製造条件を表２に示す。さらに０．８％のスキンパスを施した。
得られた鋼板のｒ値をＪＩＳ１３号Ｂ試験片で、引張試験により評価した。表２より明らかなとおり、本発明によれば良好な深絞り性を得ることができる。
Each steel having the components shown in Table 1 was melted and heated to 1250 ° C., followed by hot rolling at a finishing temperature equal to or higher than the Ar 3 transformation temperature, cooling and winding. Further, cold rolling and then annealing were performed. Various production conditions are shown in Table 2. In addition, a 0.8% skin pass was applied.
The r value of the obtained steel plate was evaluated by a tensile test using a JIS No. 13 B test piece. As apparent from Table 2, according to the present invention, good deep drawability can be obtained.
特許出願人 新日本製鐵株式会社
代理人 弁理士 椎 名 彊 他１
Patent applicant: Nippon Steel Corporation
Attorney Attorney Shiina and others 1
Claims (7)
Ｃ：０．００１０〜０．１０％、
Ｓｉ：０．００１〜２．５％、
Ｍｎ：０．０１〜３．０％、
Ｐ：０．００１〜０．１５％、
Ｓ：０．０３％以下、
Ｎ：０．０００１〜０．０１０％、
Ｍｏ：０．００５〜２．０％、
を含有し、Ａｌ、Ｔｉ，Ｎｂのうち１種または２種以上を
Ａｌ：０．００２〜０．１０％、
Ｔｉ：０．００５〜０．１０％、
Ｎｂ：０．００５〜０．１０％、
を満たすように含有し、（１）式及び（２）式を満足し、残部が鉄及び不可避的不純物からなることを特徴とする深絞り性に優れた冷延鋼板。
０．３≦Ｍｏ／Ｍｎ≦０．７ ・・・（１）
０．００１０≦Ｃ−１２×（Ｔｉ／４８＋Ｎｂ／９６−Ｎ'／１４）≦０．０８０
・・・（２）
ここでＮ'は、Ｎ≧１４／２７×Ａｌの場合は、Ｎ−１４／２７×Ａｌで計算される値、Ｎ＜１４／２７×Ａｌの場合は０とする。 % By mass
C: 0.0010 to 0.10%,
Si: 0.001 to 2.5%,
Mn: 0.01 to 3.0%,
P: 0.001 to 0.15%,
S: 0.03% or less,
N: 0.0001 to 0.010%,
Mo: 0.005 to 2.0%,
1 or 2 or more types of Al, Ti, Nb Al: 0.002-0.10%,
Ti: 0.005 to 0.10%,
Nb: 0.005 to 0.10%,
A cold-rolled steel sheet excellent in deep drawability, characterized in that it satisfies the formulas (1) and (2) and the balance is made of iron and inevitable impurities.
0.3 ≦ Mo / Mn ≦ 0.7 (1)
0.0010 ≦ C−12 × (Ti / 48 + Nb / 96−N ′ / 14) ≦ 0.080
... (2)
Here, N ′ is a value calculated by N-14 / 27 × Al when N ≧ 14/27 × Al, and is 0 when N <14/27 × Al.
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| WO2008108363A1 (en) * | 2007-03-05 | 2008-09-12 | Sumitomo Metal Industries, Ltd. | Cold-rolled steel sheet, galvannealed steel sheet and processes for production of both |
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| KR101169510B1 (en) * | 2007-03-05 | 2012-07-27 | 수미도모 메탈 인더스트리즈, 리미티드 | Cold-rolled steel sheet, galvannealed steel sheet and processes for production of both |
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| WO2008108363A1 (en) * | 2007-03-05 | 2008-09-12 | Sumitomo Metal Industries, Ltd. | Cold-rolled steel sheet, galvannealed steel sheet and processes for production of both |
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| KR101169510B1 (en) * | 2007-03-05 | 2012-07-27 | 수미도모 메탈 인더스트리즈, 리미티드 | Cold-rolled steel sheet, galvannealed steel sheet and processes for production of both |
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| CN103882293A (en) * | 2014-04-04 | 2014-06-25 | 首钢总公司 | Non-oriented electrical steel and production method thereof |
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