JP2002249849A - High tensile strength cold rolled steel sheet and production method therefor - Google Patents
High tensile strength cold rolled steel sheet and production method thereforInfo
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- JP2002249849A JP2002249849A JP2001046154A JP2001046154A JP2002249849A JP 2002249849 A JP2002249849 A JP 2002249849A JP 2001046154 A JP2001046154 A JP 2001046154A JP 2001046154 A JP2001046154 A JP 2001046154A JP 2002249849 A JP2002249849 A JP 2002249849A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、種々の形状にプレ
ス加工して使用される、引張強度が３４０ＭＰａ級以上
で、深絞り性および耐二次加工脆性の良好な高張力冷延
鋼板とその製造方法に関する。The present invention relates to a high-tensile cold-rolled steel sheet having a tensile strength of at least 340 MPa, which is excellent in deep drawability and secondary work brittleness resistance, which is used by being pressed into various shapes, and to which It relates to a manufacturing method.
【０００２】[0002]
【従来の技術】産業技術分野が高度に分業化した今日、
各技術分野において用いられる材料には、特殊かつ高度
な性能が要求されている。例えば、プレス成形して使用
される冷延鋼板についても、高い強度が要求されるよう
になり、高張力冷延鋼板の適用が検討されている。特
に、自動車用鋼板に関しては、地球環境への配慮から、
車体を軽量化して燃費を向上させるために、薄肉高張力
冷延鋼板の需要が著しく高まってきている。プレス成形
においては、使用される鋼板の厚さが薄いほど、割れや
しわが発生しやすくなるため、より深絞り性や延性に優
れた鋼板が必要とされる。しかし、これらのプレス成形
性と、鋼板の高強度化とは背反する特性であり、耐二次
加工脆性を含めて、これらの特性を同時に満足させるこ
とは困難であった。2. Description of the Related Art Today, when the industrial technology field is highly specialized,
Materials used in various technical fields are required to have special and high performance. For example, a cold-rolled steel sheet used by press forming is also required to have high strength, and application of a high-tensile cold-rolled steel sheet is being studied. In particular, regarding steel sheets for automobiles, considering the global environment,
In order to reduce the weight of a vehicle body and improve fuel efficiency, demand for a thin-walled high-tensile cold-rolled steel sheet has been significantly increased. In press forming, as the thickness of a steel sheet used is thinner, cracks and wrinkles are more likely to occur, and thus a steel sheet having more excellent deep drawability and ductility is required. However, the press formability and the strength enhancement of the steel sheet are properties that go against each other, and it has been difficult to simultaneously satisfy these properties including the resistance to secondary working embrittlement.
【０００３】これまでに、ＴｉあるいはＮｂを添加した
極低炭素鋼板、いわゆるＩＦ鋼板をベースにＰ、Ｓｉ、
ＭｎおよびＣｒ等を添加して強度を上げた深絞り用高強
度冷延鋼板については多くの提案がなされてきている。[0003] Until now, based on ultra-low carbon steel sheets added with Ti or Nb, so-called IF steel sheets, P, Si,
Many proposals have been made for a high-strength cold-rolled steel sheet for deep drawing in which Mn and Cr are added to increase the strength.
【０００４】例えば、特公昭５７−５７９４５号公報に
は、Ｔｉ添加極低炭素鋼にＰとＣｒを添加した高強度鋼
板が開示されている。しかし、粒界を脆化させるＰを多
量に含むにもかかわらず二次加工脆性に関する考慮がな
されていない。[0004] For example, Japanese Patent Publication No. 57-57945 discloses a high-strength steel sheet obtained by adding P and Cr to a Ti-added ultra-low carbon steel. However, no consideration has been given to secondary working embrittlement despite containing a large amount of P that embrittles grain boundaries.
【０００５】特公昭５９−４２７４２号公報には、Ｔｉ
添加極低炭素鋼にＰ、Ｓｉ、Ｍｎ、ＭｏおよびＣｒを添
加し、さらに二次加工脆性を改善するためにＢを添加し
た高強度冷延鋼板が開示されている。この鋼板の平均ラ
ンクフォード値(平均ｒ値)は１．６〜２．０程度であ
り、必ずしも深絞り性に優れているとは言い難い。Japanese Patent Publication No. 59-42742 discloses Ti
There is disclosed a high-strength cold-rolled steel sheet in which P, Si, Mn, Mo, and Cr are added to an added ultra-low carbon steel, and B is added in order to improve secondary work brittleness. The average Rankford value (average r value) of this steel sheet is about 1.6 to 2.0, and it cannot be said that the steel sheet is always excellent in deep drawability.
【０００６】Ｐを添加して高強度化したＴｉ添加もしく
はＴｉ−Ｎｂ添加極低炭素冷延鋼板の延性や深絞り性を
向上させることは一般に困難であるが、その原因の一つ
として、熱間圧延後に鋼帯を高温で巻取るとＦｅＴｉＰ
系化合物が析出することが知られている。[0006] It is generally difficult to improve the ductility and deep drawability of a Ti-added or Ti-Nb-added ultra-low carbon cold rolled steel sheet which has been strengthened by adding P, but one of the causes is heat. When the steel strip is wound at high temperature after hot rolling, FeTiP
It is known that a system compound precipitates.
【０００７】上記特許公報においても、ＦｅＴｉＰ系化
合物の析出を防止するために、ＴｉおよびＰ含有量に制
限を設けているが、本発明者らの検討によると、Ｔｉ含
有量が多すぎるために、十分なｒ値が得られていない。[0007] In the above-mentioned patent publications as well, the contents of Ti and P are limited in order to prevent the precipitation of FeTiP-based compounds. However, according to the study of the present inventors, the Ti content is too large. , A sufficient r value is not obtained.
【０００８】また、特開平９−１１８９５５号公報にお
いて、ＦｅＴｉＰの析出を抑制するために、Ａｌを多量
に含有させた鋼を、熱延後５５０〜６３０℃で巻取り、
冷延、焼鈍する技術が開示されている。しかし、この方
法では、Ａｌ添加によるコスト上昇を招くだけでなく、
巻取温度が比較的低いため、ＴｉＣやＮｂＣの粗大化に
よるｒ値向上効果が期待できない。さらに、ＩＦ鋼板ベ
ースの高張力鋼板では、０°方向（圧延方向）のｒ値
（ｒ0゜）が他方向に比べて低く、これがプレス成形不良
の原因となるにもかかわらず、ｒ0゜については何ら対策
が講じられていない。In Japanese Patent Application Laid-Open No. Hei 9-118555, in order to suppress the precipitation of FeTiP, a steel containing a large amount of Al is rolled at 550 to 630 ° C. after hot rolling.
A technique of cold rolling and annealing is disclosed. However, this method not only causes an increase in cost due to the addition of Al,
Since the winding temperature is relatively low, the effect of improving the r value due to coarsening of TiC or NbC cannot be expected. Furthermore, in the case of the IF steel sheet-based high-strength steel sheet, the r value (r0 の) in the 0 ° direction (rolling direction) is lower than that in the other directions, and this causes the press forming failure. No measures have been taken.
【０００９】[0009]
【発明が解決しようとする課題】本発明の課題は、引張
り強さが３４０ＭＰａ以上で、平均ｒ値および最低ｒ値
（３方向の中で最も低いｒ値）が良好であり、かつ、優
れた耐二次加工脆性を有し、コスト面でも格別の不利を
伴うことのない高張力冷延鋼板とその製造方法を提供す
ることにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a resin having an average r value and a minimum r value (the lowest r value in three directions) having a tensile strength of 340 MPa or more and an excellent r value. An object of the present invention is to provide a high-strength cold-rolled steel sheet which has secondary working brittleness and does not involve a particular disadvantage in cost, and a method for producing the same.
【００１０】[0010]
【課題を解決するための手段】本発明者らは上記課題に
対して、Ｔｉ−Ｎｂ−Ｂ添加極低炭素鋼板をベースとし
た高張力鋼板の機械的特性に及ぼす添加元素の影響につ
いて以下のような試験を実施した。Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have studied the effects of additive elements on the mechanical properties of a high-strength steel sheet based on a Ti-Nb-B-added ultra-low carbon steel sheet. Such a test was conducted.
【００１１】質量％で、Ｃ：０．００２％、Ｓｉ：０．
１％、Ｍｎ：０．１５％、Ｐ：０．０５％、Ｓ：０．０
０５％、sol．Ａｌ：０．０４％、Ｎ：０．００２％を
含み、Ｔｉを０．００５〜０．０３％、Ｎｂを０〜０．
０４％およびＢを０．０００３〜０．００１４％の範囲
で種々変化させた化学組成の鋼を溶製してインゴットと
し、分塊圧延した後９３０℃以上で熱間圧延し、６８０
℃で巻き取り、得られた熱延板を酸洗して８０％の圧延
率で冷間圧延を施し連続焼鈍した。その鋼板から圧延方
向、その方向から４５度方向および圧延方向と直交する
方向から引張試験を採取して引張試験をおこないｒ値を
測定した。In mass%, C: 0.002%, Si: 0.
1%, Mn: 0.15%, P: 0.05%, S: 0.0
05%, sol. Al: 0.04%, N: 0.002%, Ti: 0.005 to 0.03%, Nb: 0 to 0.
04% and B were melted to 0.0003 to 0.0014% of the steel chemical composition was varied in the range as ingot, hot rolling at 930 ° C. or higher after slabbing, 680
The obtained hot rolled sheet was pickled, cold rolled at a rolling ratio of 80%, and continuously annealed. A tensile test was taken from the steel sheet in the rolling direction, a 45 ° direction from that direction, and a direction perpendicular to the rolling direction, and a tensile test was performed to measure the r-value.
【００１２】図１は、（ｒ0゜＋２ｒ45゜＋ｒ90゜）／４で
定義される平均ｒ値と、Ｔｉ−（４８／１４）Ｎで定義
されるＴｉ＊と、Ｂ含有量の関係を示す図である。FIG. 1 is a diagram showing the relationship between the average r value defined by (r0 ゜ + 2r45 ゜ + r90 ゜) / 4, Ti * defined by Ti- (48/14) N, and the B content. It is.
【００１３】図２は、０°、４５°、９０°方向のｒ値
の内、最も低いｒ値とＴｉ＊、 Ｂ量の関係を示すもの
である。各図中の丸印は平均ｒ値が１．９以上、黒丸印
は平均ｒ値が１．９未満、白三角印は最低ｒ値が１．７
以上、黒三角印は最低ｒ値が１．７未満であったことを
意味する。FIG. 2 shows the relationship between the lowest r value among the r values in the 0 °, 45 °, and 90 ° directions and the amounts of Ti * and B. Circles in each figure have an average r value of 1.9 or more, black circles have an average r value of less than 1.9, and white triangles have a minimum r value of 1.7.
As described above, the black triangle means that the minimum r value was less than 1.7.
【００１４】図３は、Ｂ含有量が０．０００６％の場合
において、０°、４５°、９０°方向のｒ値とＴｉ＊の
関係を示したものである。FIG. 3 shows the relationship between the r values in the 0 °, 45 °, and 90 ° directions and Ti * when the B content is 0.0006%.
【００１５】このような結果から次のような知見を得る
に至った。The following findings have been obtained from such results.
【００１６】（ａ）図１および図２から明らかなよう
に、平均ｒ値および最低ｒ値は、Ｔｉ ＊、Ｂ含有量と相
関関係があり、ｒ 値を高くするためには、Ｂ含有量が
多くなるほどＴｉ＊ 量を減少させる必要がある。こ
の原因の詳細は不明であるが、Ｂ含有量が増すにつれて
熱延板結晶粒界中のＴｉ量が増加し、粒界中でのＦｅＴ
ｉＰの析出が促進され、これが、再結晶焼鈍時の集合組
織形成に悪影響を与えるためと推定される。(A) As apparent from FIGS. 1 and 2
In addition, the average r value and the minimum r value are Ti *, B content and phase
In order to increase the r value, the B content must be
Ti* The amount needs to be reduced. This
The details of the cause are unknown, but as the B content increases,
The amount of Ti in the grain boundaries of the hot-rolled sheet increases, and FeT in the grain boundaries increases.
The precipitation of iP is promoted, and this is
It is presumed to have an adverse effect on weave formation.
【００１７】（ｂ）図３から明らかなように、ｒ値は、
Ｔｉ＊の低下に伴い上昇するが、Ｔｉ＊×Ｂ≦４．５×
１０−６を満たす範囲における上昇量が大きい。これ
は、ＦｅＴｉＰの析出量がその範囲で非常に少なくなる
ためと考えられる。(B) As is apparent from FIG. 3, the r value is
It rises with a decrease in Ti * , but Ti ** × B ≦ 4.5 ×
The amount of rise in the range satisfying 10 −6 is large. This is presumably because the amount of FeTiP deposited becomes very small in that range.
【００１８】（ｃ）また、Ｔｉ＊ の低下に伴うｒ
値の向上は、０°方向と９０°方向で顕著である。した
がって、ＩＦ鋼板をベースにＳｉ、Ｍｎ、Ｐを添加して
高強度化した冷延鋼板において問題となる０°方向のｒ
値不足は、Ｂ含有量に応じてＴｉ＊ 含有量を極微
量化することによって改善される。(C) Further, r accompanying the decrease of Ti *
The improvement in the value is remarkable in the 0 ° direction and the 90 ° direction. Therefore, the 0 ° direction r which becomes a problem in a cold-rolled steel sheet which is strengthened by adding Si, Mn, and P based on an IF steel sheet is used.
The value deficiency is improved by minimizing the Ti * content according to the B content.
【００１９】（ｄ）熱延板中に炭化物を完全析出させる
ためには、Ｎｂを炭素当量以上に含有させたうえ、熱延
板を高温で巻取る必要があるが、多量に添加するとＦｅ
ＮｂＰが析出し、ｒ値が低下する。本発明は、上記の知
見に基づきなされたものであり、その要旨は、下記
（１）および（２）の、プレス成形性に優れた高張力冷
延鋼板と（３）、（４）の製造方法にある。(D) In order to completely precipitate carbides in the hot-rolled sheet, it is necessary to contain Nb at a carbon equivalent or more and to wind the hot-rolled sheet at a high temperature.
NbP precipitates and the r value decreases. The present invention has been made based on the above findings, and the gist of the invention is to produce the following (1) and (2) high-tensile cold-rolled steel sheets excellent in press formability and (3) and (4). In the way.
【００２０】（１）質量％で、Ｃ：０．０００５〜０．
００５％、Ｓｉ：０．５％以下、Ｍｎ：１％以下、Ｐ：
０．１％以下、Ｓ：０．０１％以下、Ｎ：０．００５％
以下、sol.Ａｌ：０．０５％以下、Ｔｉ：０．０２％以
下、Ｂ：０．０００３〜０．０１％およびＮｂを下記
式を満足する範囲で含有し、かつ下記〜式を満足
し、残部が鉄および不純物からなる高張力冷延鋼板。(1) C: 0.0005 to 0.5% by mass.
005%, Si: 0.5% or less, Mn: 1% or less, P:
0.1% or less, S: 0.01% or less, N: 0.005%
Hereinafter, sol. Al: 0.05% or less, Ti: 0.02% or less, B: 0.0003 to 0.01% and Nb are contained in a range satisfying the following formula, and satisfy the following formulas. High-strength cold-rolled steel sheet consisting of iron and impurities.
【００２１】 ２Ｓｉ＋Ｍｎ＋２０Ｐ≧１．１・・・ Ｔｉ＊×Ｂ≦４．５×１０−６ ・・・ ただし、Ｔｉ＊＝Ｔｉ−（４８／１４）Ｎ Ｔｉ−（４８／１４）Ｎ≧０ ・・・ （９３／１２）Ｃ≦Ｎｂ≦（９３／６）Ｃ・・・ 式中の元素記号は、各元素の鋼中での含有量（質量％）
を示す （２）Ｆｅの一部に代えて、さらにＣｒ、Ｗ、Ｎｉおよ
びＭｏのいずれか１種または２種以上を、合計量で０．
０５〜２％含有する上記（１）に記載の高張力冷延鋼
板。2Si + Mn + 20P ≧ 1.1 Ti * × B ≦ 4.5 × 10 −6 where Ti * = Ti− (48/14) N Ti− (48/14) N ≧ 0 ··· (93/12) C ≦ Nb ≦ (93/6) C ·················································· |
(2) Instead of a part of Fe, one or more of Cr, W, Ni and Mo are further added in a total amount of 0.1%.
The high-tensile cold-rolled steel sheet according to the above (1), which contains 0.5 to 2%.
【００２２】（３）上記（１）または（２）に記載の化
学組成を有する鋼を、Ａｒ３変態点以上の温度で熱間圧
延して６００〜７５０℃で巻取り、次いで圧下率５０％
以上の冷間圧延を施して再結晶焼鈍する高張力冷延鋼板
の製造方法。(3) A steel having the chemical composition described in the above (1) or (2) is hot-rolled at a temperature not lower than the Ar 3 transformation point and wound at 600 to 750 ° C., and then a reduction of 50%
A method for producing a high-tensile cold-rolled steel sheet which is subjected to the above cold rolling and recrystallization annealing.
【００２３】（４）請求項１または２に記載の化学組成
を有する鋼を、Ａｒ３ 変態点以上の温度で熱間圧延
して６００℃未満の温度で巻取り、次いで６００〜８０
０℃の温度範囲内で熱延板焼鈍をおこない、圧下率５０
％以上の冷間圧延を施して再結晶焼鈍する高張力冷延鋼
板の製造方法。(4) The steel having the chemical composition according to claim 1 or 2 is hot-rolled at a temperature not lower than the Ar 3 transformation point and wound at a temperature lower than 600 ° C.
Anneal the hot-rolled sheet within the temperature range of 0 ° C, and reduce the rolling reduction by 50%.
% Cold rolling of high-tensile cold-rolled steel sheet which is subjected to recrystallization annealing after cold rolling of at least 30%.
【００２４】[0024]
【発明の実施の形態】以下に、本発明の実施の形態につ
いて詳細に述べる。なお、以下に述べる化学組成の％表
示は質量％を示す。Embodiments of the present invention will be described below in detail. The chemical composition described below in% represents mass%.
【００２５】鋼の化学組成 Ｃ：Ｃ含有量が０．００５％を超えると、Ｎｂの必要添
加量が増加してコスト上昇につながるばかりでなく、Ｎ
ｂＣの析出量が多くなり、鋼板の深絞り性が損なわれ
る。一方、過度に極低炭素化することは、製造コストの
上昇を伴うだけでなく、ＮｂＣの析出が不十分となり固
溶Ｃが残存し、深絞り性劣化の原因となる。そのため、
Ｃ含有量の範囲は０．０００５〜０．００５％とした。
望ましくは０．００１５〜０．００４％である。 Chemical composition C of steel : If the C content exceeds 0.005%, not only does the required amount of Nb increase, leading to an increase in cost, but also to an increase in N content.
The precipitation amount of bC increases, and the deep drawability of the steel sheet is impaired. On the other hand, excessively low carbon causes not only an increase in production cost, but also insufficient precipitation of NbC, so that solid solution C remains and causes deep drawability deterioration. for that reason,
The range of the C content was 0.0005 to 0.005%.
Desirably, it is 0.0015 to 0.004%.
【００２６】Ｓｉ：Ｓｉは、鋼中に必然的に含有される
元素であるが、鋼板の化成処理性を著しく劣化させる。
また、めっき鋼板を製造する場合、めっき密着性を低下
させる。したがって、その含有量は少ないほど好まし
い。しかし、鋼板を強化する作用を有するので、鋼を強
化する目的で、最高０．５％まで含有させることができ
る。望ましいのは、０．１％以下とすることである。Si: Si is an element inevitably contained in steel, but significantly degrades the chemical conversion property of a steel sheet.
Further, when producing a plated steel sheet, the plating adhesion is reduced. Therefore, the smaller the content, the better. However, since it has the effect of strengthening the steel sheet, it can be contained up to 0.5% for the purpose of strengthening the steel. Desirably, the content is 0.1% or less.
【００２７】Ｍｎ：Ｍｎは、不純物であるＳと結合して
ＭｎＳを形成し、Ｓの弊害を抑制するほか、表面性状を
損なうことなく鋼板を強化する作用を有するので、所望
の強度を得るために式、２Ｓｉ＋Ｍｎ＋２０Ｐ≧１．
１を満たす範囲で含有させる。ただし、多量に添加する
と、加工性が低下するので１％以下と定めた。望ましく
は、０．４％以下である。Mn: Mn combines with S as an impurity to form MnS, suppresses the adverse effects of S, and has the effect of strengthening the steel sheet without impairing the surface properties. In the formula, 2Si + Mn + 20P ≧ 1.
It is contained within a range satisfying 1. However, when added in a large amount, the workability is reduced, so that the content is set to 1% or less. Desirably, it is 0.4% or less.
【００２８】Ｐ：Ｐは、鋼中に必然的に含有される元素
である。鋼板を強化する作用が強く、安価に鋼を強化す
ることができるため、所望の強度を得るために、式、
２Ｓｉ＋Ｍｎ＋２０Ｐ≧１．１を満たす範囲で含有させ
る。しかし、粒界に偏析して鋼を脆化させ、その含有量
が０．１％を超えると、二次加工脆化を抑制するために
多量のＢが必要となり、深絞り性の劣化を招く。このた
め、Ｐ含有量の上限を０．１％とする。好ましい上限
は、０．０５５％である。P: P is an element necessarily contained in steel. Since the effect of strengthening the steel sheet is strong and the steel can be strengthened inexpensively, in order to obtain the desired strength, the formula:
It is contained in a range satisfying 2Si + Mn + 20P ≧ 1.1. However, when the steel segregates at the grain boundaries to embrittle the steel and its content exceeds 0.1%, a large amount of B is required to suppress the embrittlement of secondary working, and the deep drawability is deteriorated. . For this reason, the upper limit of the P content is set to 0.1%. A preferred upper limit is 0.055%.
【００２９】Ｓ：Ｓも鋼中に必然的に含有される元素で
あり、粒界に偏析して鋼を脆化させるため、その含有量
は少ないほど好ましいが、０．０１％まで許容できるの
で上限を０．０１％とした。S: S is also an element that is inevitably contained in steel, and segregates at the grain boundaries to embrittle the steel. Therefore, the smaller the content, the better, but it is acceptable up to 0.01%. The upper limit was set to 0.01%.
【００３０】sol.Ａｌ：Ａｌは、溶鋼を脱酸するために
用いる。しかし、０．０５％を超えて含有させると、効
果が飽和して不経済であるばかりか、延性を損なうよう
になる。このため、sol．Ａｌの含有量は０．０５％以
下と定めた。Sol.Al: Al is used for deoxidizing molten steel. However, when the content exceeds 0.05%, the effect is saturated and not only is uneconomical, but also impairs ductility. For this reason, sol. The content of Al was determined to be 0.05% or less.
【００３１】Ｎ：Ｎは、鋼中に必然的に含有される元素
であり、深絞り性を劣化させる元素である。また、Ｎ含
有量が多くなると必要なＴｉ添加量が多くなり、コスト
アップを招くだけでなく、ＴｉＮの析出量が多くなり、
延性を損なうようになるため、０．００５％以下と定め
た。Ｔｉ：Ｔｉは、鋼板中のＮをＴｉＮとして固定し、
深絞り性に好ましい再結晶集合組織を発達させる作用を
有しており、本発明における重要な構成成分である。Ｔ
ｉ含有量が（４８／１４）Ｎ％を下回ると、固溶Ｎが残
存し、上記作用による所望の効果を確保することができ
ず、深絞り性が損なわれる。[0031] N: N is an element inevitably included in steel, is an element deteriorating the deep drawability. In addition, when the N content increases, the necessary Ti addition amount increases, which not only causes an increase in cost, but also increases the amount of TiN deposited,
Since the ductility is impaired, the content is set to 0.005% or less. Ti: Ti fixes N in the steel sheet as TiN,
It has the effect of developing a recrystallized texture preferable for deep drawability, and is an important component in the present invention. T
If the i content is less than (48/14) N%, solid solution N remains, and the desired effect of the above-mentioned action cannot be secured, and the deep drawability is impaired.
【００３２】一方、Ｔｉ含有量が過剰となると、熱延後
に、ＦｅＴｉＰが析出して、冷延−焼鈍後の深絞り性と
延性の劣化を招く。特に、Ｂ添加によってＦｅＴｉＰが
析出しやすくなるため、Ｂ添加量に応じてＴｉ量を低減
させる必要がある。これらの理由から、Ｔｉ含有量を
０．０２％以下で、かつ、下記、式を満たす範囲と
した。On the other hand, if the Ti content is excessive, FeTiP precipitates after hot rolling, which causes deterioration in deep drawability and ductility after cold rolling and annealing. In particular, since FeTiP is easily precipitated by adding B, it is necessary to reduce the amount of Ti according to the amount of B added. For these reasons, the content of Ti is set to 0.02% or less and to satisfy the following formula.
【００３３】 Ｔｉ＊×Ｂ≦４．５×１０−６・・・ ただし、Ｔｉ＊＝Ｔｉ−（４８／１４）Ｎ Ｔｉ−（４８／１４）Ｎ≧０・・・ Ｎｂ：Ｎｂは、鋼板中のＣをＮｂＣとして固定して深絞
り性に好ましい再結晶集合組織を発達させる作用を有す
るので、（９３／１２）Ｃ％以上含有させる。しかし、
Ｎｂ量が過剰となると、再結晶温度が上昇してしまうだ
けでなく、ＦｅＮｂＰの析出量が増し、深絞り性と延性
が損なわれるので、上限を（９３／６）Ｃ％とした。望
ましいのは、（９３／８）Ｃ％以下である。Ti * × B ≦ 4.5 × 10 −6 , where Ti * = Ti− (48/14) N Ti− (48/14) N ≧ 0... Nb: Nb is a steel plate C in the steel is fixed as NbC and has an effect of developing a recrystallized texture preferable for deep drawability, so that it is contained in an amount of (93/12) C% or more. But,
If the amount of Nb is excessive, not only does the recrystallization temperature rise, but also the amount of FeNbP deposited increases, and the deep drawability and ductility are impaired. Therefore, the upper limit was set to (93/6) C%. Desirable is (93/8) C% or less.
【００３４】Ｂ：Ｂは、結晶粒界に偏析して粒界を強化
するので、耐二次加工脆性を向上させるために０．００
０３％以上含有させる。しかし、過剰なＢ添加は、再結
晶温度を上昇させるばかりか、ＦｅＴｉＰの析出を促進
させ、深絞り性と延性が損なわれる。したがって、Ｂ含
有量を０．０００３〜０．０１％と定めた。望ましく
は、０．０００３〜０．００１５％である。B: Since B segregates at crystal grain boundaries and strengthens the grain boundaries, B is added in an amount of 0.000% to improve the resistance to secondary working embrittlement.
More than 03% is contained. However, excessive addition of B not only raises the recrystallization temperature but also promotes the precipitation of FeTiP, and impairs deep drawability and ductility. Therefore, the B content was determined to be 0.0003 to 0.01%. Desirably, it is 0.0003 to 0.0015%.
【００３５】Ｃｒ、Ｗ、Ｎｉ、Ｍｏ：これらの元素は、
鋼板を強化する作用と、耐食性を向上させる作用がある
ため、必要に応じて１種または２種以上含有させる。た
だし、含有量の合計が０．０５％未満では、所望の効果
が得られず、一方、２％を超えると延性が著しく劣化す
る。したがって、合計の含有量を０．０５〜２％と定め
た。Cr, W, Ni, Mo: These elements are
Since it has the effect of strengthening the steel sheet and the effect of improving the corrosion resistance, one or more of these may be contained as necessary. However, if the total content is less than 0.05%, the desired effect cannot be obtained, while if it exceeds 2%, the ductility is significantly deteriorated. Therefore, the total content was determined to be 0.05 to 2%.
【００３６】製造条件 熱間圧延：上記した化学組成を有する鋼を溶製し、連続
鋳造法により鋳片とするかまたはインゴットケースに鋳
込み鋳塊にした後、分塊圧延等の方法で鋼片とし、この
鋼片は再加熱するか、連続鋳造または分塊圧延後の高温
の鋼片をそのまま、または、補助加熱を施して熱間圧延
する。 Manufacturing conditions Hot rolling: A steel having the above-described chemical composition is melted and cast into a slab by a continuous casting method or cast into an ingot case and then cast into a slab by a method such as slab rolling. The steel slab is re-heated, hot-rolled as it is after continuous casting or slab rolling, or hot-rolled with auxiliary heating.
【００３７】熱間圧延での圧延終了温度がＡｒ３ 変
態点を下回ると、表層に深絞り性を阻害する圧延集合組
織が形成されるために、Ａｒ３ 変態点以上の温度で
熱間圧延をおこなう。好ましくは、結晶粒の微細化を図
るという観点から、Ａｒ３変態点〜Ａｒ３ 変態点＋
５０℃の間で、最終圧下をおこなう。なお、圧延終了温
度をＡｒ３ 点以上の温度とするために、粗圧延と仕上
げ圧延の間で、粗圧延された鋼帯すなわち粗圧延材を加
熱してもよい。この際、鋼帯の後端が先端よりも高温と
なるように加熱し、仕上げ圧延開始時の鋼帯全長にわた
る温度の変動が、１４０℃以下となるようにすることが
望ましい。これにより、製品特性のコイル内均一性が向
上する。粗圧延材の加熱は、例えば粗圧延機と仕上げ圧
延機との間にソレノイド式誘導加熱装置を設け、誘導加
熱装置前の粗圧延材の長手方向温度分布などに基づいて
加熱昇温量を制御することにより可能である。When the rolling end temperature in the hot rolling is lower than the Ar 3 transformation point, a rolling texture that inhibits the deep drawing property is formed on the surface layer, so that hot rolling is performed at a temperature equal to or higher than the Ar 3 transformation point. Do it. Preferably, from the viewpoint of miniaturization of crystal grains, Ar 3 transformation point to Ar 3 transformation point +
A final reduction is performed between 50 ° C. Note that, in order to set the rolling end temperature to a temperature of three or more points of Ar, the rough-rolled steel strip, that is, the rough-rolled material may be heated between the rough rolling and the finish rolling. At this time, it is desirable to heat the rear end of the steel strip so as to be higher than the front end, so that the temperature fluctuation over the entire length of the steel strip at the start of the finish rolling is 140 ° C. or less. Thereby, the uniformity of the product characteristics in the coil is improved. For heating the rough rolled material, for example, a solenoid-type induction heating device is provided between the rough rolling mill and the finish rolling mill, and the heating temperature is controlled based on the longitudinal temperature distribution of the rough rolled material before the induction heating device. It is possible by doing.
【００３８】熱間圧延後は、鋼板を巻取温度まで冷却
し、６００℃以上でコイル状に巻取るのがよい。巻取温
度が６００℃未満と低いと、ＮｂＣの粗大化が不十分と
なって製品鋼板に良好な延性を付与できないばかりか、
冷延後の再結晶焼鈍において深絞り性に好ましい再結晶
集合組織が十分に発達しない。一方、巻取温度が７５０
℃を上回ると、ＦｅＴｉＰの析出量が増し、深絞り性と
延性の劣化を招く。したがって、巻取温度の範囲を６０
０〜７５０℃と定めた。好ましくは、６５０℃〜７５０
℃の範囲である。After hot rolling, the steel sheet is preferably cooled to a winding temperature and wound at 600 ° C. or higher into a coil. If the winding temperature is as low as less than 600 ° C., the coarsening of NbC becomes insufficient and not only good ductility cannot be imparted to the product steel sheet, but also
In recrystallization annealing after cold rolling, a recrystallization texture preferable for deep drawability is not sufficiently developed. On the other hand, when the winding temperature is 750
When the temperature exceeds ℃, the precipitation amount of FeTiP increases, which causes deterioration in deep drawability and ductility. Therefore, the range of the winding temperature is 60
0-750 ° C. Preferably, 650 ° C. to 750
It is in the range of ° C.
【００３９】ただし、冷間圧延工程の前に、熱延コイル
に焼鈍を施す場合、すなわち熱延板焼鈍を施す場合に
は、焼鈍中にＮｂＣが粗大化するため、熱間圧延後の巻
取り温度は６００℃未満であってもよい。熱延板焼鈍の
温度が６００℃未満ではＮｂＣの粗大化が不十分となり
良好な延性が得られず、８００℃超えでは結晶粒が粗大
化して深絞り性が劣化する。したがって、熱延板焼鈍の
温度範囲を６００〜８００℃と定めた。好ましくは６５
０〜７５０℃の範囲である。However, if the hot-rolled coil is annealed before the cold-rolling step, that is, if the hot-rolled sheet is annealed, NbC becomes coarse during the annealing. The temperature may be below 600 ° C. If the temperature of the hot-rolled sheet annealing is lower than 600 ° C., coarsening of NbC becomes insufficient and good ductility cannot be obtained. If the temperature exceeds 800 ° C., crystal grains become coarse and deep drawability deteriorates. Therefore, the temperature range of hot-rolled sheet annealing was set to 600 to 800 ° C. Preferably 65
The range is from 0 to 750 ° C.
【００４０】冷間圧延：冷間圧延は、常法に従い、酸洗
等により脱スケールした後でおこなう。再結晶焼鈍によ
って深絞り性に好ましい再結晶集合組織を発達させるた
めに、圧下率を５０％以上とした。Cold rolling: Cold rolling is performed after descaling by pickling or the like according to a conventional method. In order to develop a recrystallized texture favorable for deep drawability by recrystallization annealing, the rolling reduction was set to 50% or more.
【００４１】焼鈍：冷間圧延した鋼板は、必要に応じて
公知の方法に従って脱脂などの処理を施して再結晶焼鈍
する。この際の焼鈍温度は、再結晶温度以上でＡｃ３
変態点未満の温度範囲とする。焼鈍温度がＡｃ３
変態点以上になると、深絞り性に好ましい再結晶集合組
織が変態により減少するので好ましくない。Annealing: The cold-rolled steel sheet is subjected to a treatment such as degreasing according to a known method, if necessary, and then annealed for recrystallization. Annealing temperature at this time, Ac 3 in the recrystallization temperature or higher
The temperature range is below the transformation point. Annealing temperature is Ac 3
If the transformation temperature is higher than the transformation point, the recrystallization texture preferred for deep drawability is undesirably reduced by transformation.
【００４２】焼鈍後は、常法にしたがって調質圧延を施
すのが望ましいが、調質圧延を省略してもかまわない。
本発明の製造方法にしたがって製造される冷延鋼板は、
これを母材として電気めっきを施したり、塗装鋼板にし
て用いることもできる。冷間圧延後の鋼板を、公知の溶
融めっき装置に装備されている加熱炉で焼鈍して、溶融
めっきして、めっき鋼板や合金化溶融めっき鋼板にする
こともできる。もちろん、連続焼鈍炉で焼鈍を施した
後、溶融めっきを施して、めっき鋼板や合金化溶融めっ
き鋼板にしてもよい。After annealing, it is desirable to perform temper rolling in accordance with a conventional method, but temper rolling may be omitted.
Cold rolled steel sheet manufactured according to the manufacturing method of the present invention,
This can be used as a base material for electroplating or as a coated steel plate. The steel sheet after the cold rolling can be annealed in a heating furnace provided in a known hot-dip coating apparatus and hot-dip coated to form a coated steel sheet or an alloyed hot-dip coated steel sheet. Of course, after annealing in a continuous annealing furnace, hot-dip coating may be performed to form a plated steel sheet or an alloyed hot-dip coated steel sheet.
【００４３】[0043]
【実施例】真空溶解炉を用いて、表１に示す１８種の化
学組成を有する鋼を溶解し、各５０ｋｇ鋼塊とした。こ
れらの鋼塊を熱間鍛造して２５ｍｍ厚の鋼片とし、電気
加熱炉を用いて１２００℃に加熱して１時間保持し、熱
間圧延機により、１１５０℃から９３０℃の温度範囲で
圧延して厚さ５ｍｍの熱延鋼板とし、熱延後直ちに強制
空冷あるいは水スプレー冷却により４５０〜７００℃の
温度範囲内の種々の温度にまで冷却してこれを巻取温度
とし、その温度に保持された電気加熱炉中に挿入して１
時間保持した後、２０℃／時の冷却速度で炉冷して巻取
後の徐冷処理とした。EXAMPLES Using a vacuum melting furnace, steels having the eighteen chemical compositions shown in Table 1 were melted to form ingots of 50 kg each. These ingots were hot forged into 25 mm thick slabs, heated to 1200 ° C. using an electric heating furnace, held for 1 hour, and rolled in a temperature range of 1150 ° C. to 930 ° C. by a hot rolling mill. Hot rolled steel sheet with a thickness of 5 mm, and immediately after hot rolling, it is cooled to various temperatures within the temperature range of 450 to 700 ° C by forced air cooling or water spray cooling, and this is taken as the winding temperature and maintained at that temperature. Inserted into a heated electric furnace
After holding for a time, the furnace was cooled at a cooling rate of 20 ° C./hour to perform a slow cooling treatment after winding.
【００４４】[0044]
【表１】 得られた鋼板の両表面を研削して厚さ４ｍｍ厚の冷延用
母材とし、その一部には７００℃にて６時間の箱焼鈍相
当の焼鈍を施した。各鋼板を、圧下率８５％で冷間圧延
し、８５０℃で４０秒間保持する連続焼鈍相当の再結晶
焼鈍を施した。その後、これらの焼鈍板に、伸び率０．
８％の調質圧延を施し、その性能を評価した。ｒ値は、
圧延方向、４５度方向および幅方向から採取したＪＩＳ
５号引張試験片で引張試験して測定した。[Table 1] Both surfaces of the obtained steel sheet were ground to form a base material for cold rolling having a thickness of 4 mm, and a part thereof was subjected to annealing equivalent to box annealing at 700 ° C. for 6 hours. Each steel sheet was cold-rolled at a rolling reduction of 85% and subjected to recrystallization annealing equivalent to continuous annealing held at 850 ° C. for 40 seconds. Then, the elongation rate of these annealed sheets was set at 0.
8% temper rolling was performed, and the performance was evaluated. The r value is
JIS sampled from rolling direction, 45 degree direction and width direction
It was measured by performing a tensile test on a No. 5 tensile test piece.
【００４５】二次加工脆性は、以下の方法で評価した。
それぞれの冷延鋼板から直径５９．４ｍｍの円形深絞り
試験片を採取し、円筒深絞り試験機を用いて、絞り比
１．８の深絞り成形を施して直径３３ｍｍの円筒状カッ
プを成形した。The secondary work brittleness was evaluated by the following method.
A circular deep-drawn test specimen having a diameter of 59.4 mm was sampled from each cold-rolled steel sheet, and deep-drawn with a drawing ratio of 1.8 using a cylindrical deep-drawing tester to form a cylindrical cup having a diameter of 33 mm. .
【００４６】これらの円筒状カップの耳部を切削除去し
て、深さ１７ｍｍの円筒状のカップとし、鋼板の二次加
工脆性を測定する試料とした。先端角度６０度の円錐台
状の金型に、種々の温度に冷却した上記の円筒状カップ
を底面を上にしてかぶせ、その上方８０ｃｍの高さから
質量５ｋｇのおもりを円筒状カップの底面に落下させ、
円筒状カップの側壁部分に脆性割れの発生する臨界温度
を求め、これを、耐二次加工脆性の指標とした。The ears of these cylindrical cups were cut and removed to form cylindrical cups having a depth of 17 mm, which were used as samples for measuring the secondary working brittleness of steel plates. The above cylindrical cup cooled to various temperatures is covered with the bottom face up on a truncated cone-shaped mold with a tip angle of 60 degrees, and a weight of 5 kg from the height of 80 cm above is placed on the bottom face of the cylindrical cup. Let it fall,
The critical temperature at which a brittle crack occurred on the side wall of the cylindrical cup was determined, and this was used as an index of secondary working brittleness resistance.
【００４７】試作した冷延鋼板の、巻取温度と熱延板焼
鈍の有無と性能評価結果を表２に示した。Table 2 shows the winding temperature, the presence / absence of hot-rolled sheet annealing, and the performance evaluation results of the prototype cold-rolled steel sheet.
【００４８】[0048]
【表２】 本発明で規定する範囲内の条件で製造された本発明例の
冷延鋼板（試番２、５〜７、９、１１、１７、１８およ
び２７〜３１）は、いずれも、引張強度（ＴＳ）が３４
０ＭＰａ以上であり、かつ、平均ｒ値２．０以上、最低
ｒ値１．８以上であった。また、これらの冷延鋼板から
成形された円筒状カップの脆性遷移温度はいずれも−７
０℃以下で、良好な耐二次加工脆性を示した。鋼の組成
が、本発明で規定する範囲から外れる鋼（鋼Ａ、Ｃ、
Ｄ、Ｈ、Ｊ、Ｌ〜Ｐ）を用いて製造された冷延鋼板（試
番１、３、４、８、１０、１２〜１６、１９、２５、２
６、３２）は、上記の４特性の内のいずれかが不芳であ
った。[Table 2] Each of the cold-rolled steel sheets (sample numbers 2, 5 to 7, 9, 11, 17, 18, 18 and 27 to 31) of the present invention manufactured under the conditions defined in the present invention has a tensile strength (TS ) Is 34
It was 0 MPa or more, the average r value was 2.0 or more, and the minimum r value was 1.8 or more. In addition, the brittle transition temperature of the cylindrical cups formed from these cold-rolled steel sheets was -7.
At 0 ° C. or lower, good secondary work brittleness resistance was exhibited. Steel (steel A, C, steel) whose steel composition is out of the range specified in the present invention.
D, H, J, L to P) cold-rolled steel sheets (sample numbers 1, 3, 4, 8, 10, 12 to 16, 19, 25, 2)
6, 32) were unsatisfactory in any of the above four characteristics.
【００４９】具体的には、鋼Ａを用いた試番１、１９、
２５は、鋼のＢ含有量が少なすぎるために脆性遷移温度
が−３０℃以上と高く、耐二次加工脆性が不芳であっ
た。More specifically, test numbers 1, 19 using steel A,
In No. 25, since the B content of the steel was too small, the brittle transition temperature was as high as −30 ° C. or higher, and the secondary working brittleness resistance was poor.
【００５０】鋼Ｃ、Ｈ、Ｊ、Ｌを用いた試番３、８、１
０、１２、２６、３２では、鋼のＴｉ含有量とＢ含有量
の関係が前述の式を満たさないために、また、鋼Ｄを
用いた試番４では、Ｔｉ含有量が少なく、前述の式を
満たさないために、平均ｒ値と最低ｒ値がそれぞれ、
１．９未満、１．７未満であり、深絞り性が不芳であっ
た。Test No. 3, 8, 1 using steels C, H, J, L
In Nos. 0, 12, 26, and 32, the relationship between the Ti content and the B content of the steel does not satisfy the above-described formula, and in Test No. 4 using steel D, the Ti content was small, In order not to satisfy the formula, the average r value and the minimum r value are respectively
It was less than 1.9 and less than 1.7, and the deep drawability was poor.
【００５１】さらに、鋼Ｍ、Ｎを用いた試番１３、１４
では、Ｎｂ量が前述の式を満たさないために、深絞り
性が不芳であった。鋼Ｏ、Ｐを用いた試番１５、１６で
は、鋼のＳｉ、Ｍｎ、Ｐ含有量が少なく、前述の式を
満たさないため、引張強度が３４０ＭＰａ未満であり、
目標の強度を有していなかった。Further, trial numbers 13 and 14 using steels M and N
In this case, since the Nb content did not satisfy the above-mentioned formula, the deep drawability was poor. In Test Nos. 15 and 16 using steels O and P, the contents of Si, Mn, and P in the steel were small and did not satisfy the above-described formula, so that the tensile strength was less than 340 MPa,
Did not have the desired intensity.
【００５２】一方、鋼の化学組成は本発明の方法で規定
する条件の範囲内であるが、その他の条件が、本発明の
方法で規定する範囲を外れる条件で製造された比較例の
冷延鋼板（試番２０〜２４）では、耐二次加工脆性は良
好であるものの、巻取温度が低かったために、深絞り性
が不芳であった。On the other hand, the chemical composition of the steel is within the range defined by the method of the present invention, but the other conditions are out of the range defined by the method of the present invention. In the steel plate (test numbers 20 to 24), the secondary work brittleness resistance was good, but the deep drawing property was poor because the winding temperature was low.
【００５３】[0053]
【発明の効果】本発明によれば、プレス成形などの加工
に適用できる十分な成形性を有し、かつ、耐２次加工脆
性に優れた、３４０ＭＰａ級以上の高張力鋼鈑を得るこ
とができる。これにより、地球環境問題から自動車の燃
費改善への社会的要求が高まっている昨今、車体の軽量
化に大きく寄与できるなど、極めて有用な効果がもたら
される。According to the present invention, it is possible to obtain a high-tensile steel sheet having a formability of 340 MPa or higher, which has sufficient formability applicable to processing such as press forming and has excellent secondary work brittleness resistance. it can. As a result, an extremely useful effect is brought about, such as being able to greatly contribute to weight reduction of a vehicle body in recent years where social demands for improving fuel efficiency of automobiles are increasing due to global environmental problems.
【図１】平均ｒ値とＴｉ＊とＢ含有量の関係を示す図で
ある。（Ｔｉ＊＝Ｔi−（４８／１４）Ｎ）FIG. 1 is a diagram showing a relationship between an average r value, Ti * and B content. (Ti * = Ti- (48/14) N)
【図２】最低ｒ値とＴｉ＊とＢ含有量の関係を示す図で
ある。（Ｔｉ＊＝Ｔi−（４８／１４）Ｎ）FIG. 2 is a diagram showing a relationship between a minimum r value, Ti *, and B content. (Ti * = Ti- (48/14) N)
【図３】Ｂを０．０００６％含有する鋼の、ｒ値とＴｉ
＊の関係を示す図である。FIG. 3 shows the r value and Ti of steel containing 0.0006% of B.
It is a figure which shows the relationship of * .
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 4K037 EA01 EA02 EA04 EA11 EA15 EA17 EA18 EA19 EA20 EA23 EA25 EA27 EA31 EA33 EB01 EB02 EB08 EC01 FC07 FE02 FE03 FE05 FF02 HA02 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K037 EA01 EA02 EA04 EA11 EA15 EA17 EA18 EA19 EA20 EA23 EA25 EA27 EA31 EA33 EB01 EB02 EB08 EC01 FC07 FE02 FE03 FE05 FF02 HA02
Claims (4)
％、Ｓｉ：０．５％以下、Ｍｎ：１％以下、Ｐ：０．１
％以下、Ｓ：０．０１％以下、Ｎ：０．００５％以下、
sol.Ａｌ：０．０５％以下、Ｔｉ：０．０２％以下、
Ｂ：０．０００３〜０．０１％およびＮｂを下記式を
満足する範囲で含有し、かつ下記〜式を満足し、残
部が鉄および不純物からなる高張力冷延鋼板。 ２Ｓｉ＋Ｍｎ＋２０Ｐ≧１．１・・・ Ｔｉ＊×Ｂ≦４．５×１０−６ ・・・ ただし、Ｔｉ＊＝Ｔｉ−（４８／１４）Ｎ Ｔｉ−（４８／１４）Ｎ≧０ ・・・ （９３／１２）Ｃ≦Ｎｂ≦（９３／６）Ｃ・・・ 各式中の元素記号は、各元素の鋼中での含有量（質量
％）を示す。(1) C: 0.0005 to 0.005 by mass%
%, Si: 0.5% or less, Mn: 1% or less, P: 0.1
%, S: 0.01% or less, N: 0.005% or less,
sol. Al: 0.05% or less, Ti: 0.02% or less,
B: A high-tensile cold-rolled steel sheet containing 0.0003 to 0.01% and Nb in a range that satisfies the following formula, and satisfies the following formula, and the balance consists of iron and impurities. 2Si + Mn + 20P ≧ 1.1 Ti * × B ≦ 4.5 × 10 −6 where Ti * = Ti− (48/14) N Ti− (48/14) N ≧ 0 ( 93/12) C ≤ Nb ≤ (93/6) C ... The element symbol in each formula indicates the content (% by mass) of each element in the steel.
ｉおよびＭｏのいずれか１種または２種以上を、合計量
で０．０５〜２％含有する請求項１に記載の高張力冷延
鋼板。2. Cr, W, N
The high-tensile cold-rolled steel sheet according to claim 1, wherein one or more of i and Mo are contained in a total amount of 0.05 to 2%.
る鋼を、Ａｒ３ 変態点以上の温度で熱間圧延して６
００〜７５０℃で巻取り、次いで圧下率５０％以上の冷
間圧延を施して再結晶焼鈍する高張力冷延鋼板の製造方
法。3. A steel having the chemical composition according to claim 1 or 2, which is hot-rolled at a temperature not lower than the Ar 3 transformation point.
A method for producing a high-tensile cold-rolled steel sheet which is wound at a temperature of 00 to 750 ° C., and then subjected to cold rolling at a rolling reduction of 50% or more and recrystallization annealing.
る鋼を、Ａｒ３ 変態点以上の温度で熱間圧延して６
００℃未満の温度で巻取り、次いで６００〜８００℃の
温度範囲内で熱延板焼鈍をおこない、圧下率５０％以上
の冷間圧延を施して再結晶焼鈍する高張力冷延鋼板の製
造方法。4. A steel having the chemical composition according to claim 1 or 2 which is hot-rolled at a temperature not lower than the Ar 3 transformation point.
A method for producing a high-tensile cold-rolled steel sheet which is wound at a temperature of less than 00 ° C., then annealed in a hot rolled sheet in a temperature range of 600 to 800 ° C., subjected to cold rolling at a reduction of 50% or more, and reannealed by recrystallization. .
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006328443A (en) * | 2005-05-23 | 2006-12-07 | Sumitomo Metal Ind Ltd | Cold-rolled steel sheet with high tensile strength and manufacturing method therefor |
| JP2008110387A (en) * | 2006-10-31 | 2008-05-15 | Nippon Steel Corp | Method for producing bake-hardenable cold rolled steel sheet having excellent ductility and cold aging resistance |
| JP2010059477A (en) * | 2008-09-03 | 2010-03-18 | Sumitomo Metal Ind Ltd | High tensile strength cold rolled steel sheet |
| JP2012077384A (en) * | 2011-11-24 | 2012-04-19 | Sumitomo Metal Ind Ltd | High tensile strength cold rolled steel sheet and production method therefor |
| US10704116B2 (en) | 2015-06-05 | 2020-07-07 | Posco | High-strength thin steel sheet with excellent drawability and bake hardenability, and method for manufacturing same |
| CN115074520A (en) * | 2022-05-20 | 2022-09-20 | 本钢板材股份有限公司 | Method for controlling shape of extremely-thin wide cold-rolled outer plate |
-
2001
- 2001-02-22 JP JP2001046154A patent/JP3775225B2/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006328443A (en) * | 2005-05-23 | 2006-12-07 | Sumitomo Metal Ind Ltd | Cold-rolled steel sheet with high tensile strength and manufacturing method therefor |
| JP2008110387A (en) * | 2006-10-31 | 2008-05-15 | Nippon Steel Corp | Method for producing bake-hardenable cold rolled steel sheet having excellent ductility and cold aging resistance |
| JP2010059477A (en) * | 2008-09-03 | 2010-03-18 | Sumitomo Metal Ind Ltd | High tensile strength cold rolled steel sheet |
| JP2012077384A (en) * | 2011-11-24 | 2012-04-19 | Sumitomo Metal Ind Ltd | High tensile strength cold rolled steel sheet and production method therefor |
| US10704116B2 (en) | 2015-06-05 | 2020-07-07 | Posco | High-strength thin steel sheet with excellent drawability and bake hardenability, and method for manufacturing same |
| CN115074520A (en) * | 2022-05-20 | 2022-09-20 | 本钢板材股份有限公司 | Method for controlling shape of extremely-thin wide cold-rolled outer plate |
| CN115074520B (en) * | 2022-05-20 | 2023-11-14 | 本钢板材股份有限公司 | Method for controlling shape of extremely-thin wide cold-rolled outer plate |
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|---|---|
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