JPH08109416A - Production of baking-hardened-type cold rolled steel sheet excellent in formability - Google Patents
Production of baking-hardened-type cold rolled steel sheet excellent in formabilityInfo
- Publication number
- JPH08109416A JPH08109416A JP24928794A JP24928794A JPH08109416A JP H08109416 A JPH08109416 A JP H08109416A JP 24928794 A JP24928794 A JP 24928794A JP 24928794 A JP24928794 A JP 24928794A JP H08109416 A JPH08109416 A JP H08109416A
- Authority
- JP
- Japan
- Prior art keywords
- mass
- rolling
- less
- cooling
- rolled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、自動車用鋼板等の使
途に好適な面内異方性および深絞り性等成形性に優れる
焼付硬化型冷延鋼板の製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a bake hardening type cold rolled steel sheet which is suitable for use in automobile steel sheets and the like and which is excellent in formability such as in-plane anisotropy and deep drawability.
【０００２】自動車のパネル等に使用される冷延鋼板に
は、その特性として面内異方性の小さいことや深絞り性
に優れていることが要求される。この深絞り性の向上に
は、鋼板の機械的特性として、ｒ値（ランクフォード
値）や伸び(El)を向上させることが重要である。このよ
うな鋼板には、近年、連続焼鈍に代表される短時間加熱
−冷却の熱サイクルからなる焼鈍プロセスで、優れた深
絞り性が得られる極低炭素ＩＦ鋼が多量に使用されるよ
うになってきている。Cold rolled steel sheets used for automobile panels and the like are required to have small in-plane anisotropy and excellent deep drawability. In order to improve the deep drawability, it is important to improve the r value (Rankford value) and the elongation (El) as mechanical properties of the steel sheet. In recent years, a large amount of ultra-low carbon IF steel, which has excellent deep drawability, is used for such a steel sheet in an annealing process consisting of a short-time heating-cooling heat cycle represented by continuous annealing. It has become to.
【０００３】一方、昨今の製鋼での脱ガス技術の進歩と
その技術の普及により、ＣやＮの含有量が20mass ppm以
下の鋼が効率的かつ大量に製造されるようになってき
た。このような極低炭素鋼では、伸びの向上ははかれる
ものの熱延板の結晶粒の粗大化がおこりやすく、このた
め、冷間圧延、焼鈍後の深絞り性を劣化させることか
ら、より高いｒ値を得るためには、熱延板の結晶粒径の
微細化をはかる技術の開発が重要になる。On the other hand, due to the recent progress of degassing technology in steelmaking and the widespread use of the technology, steel with a C or N content of 20 mass ppm or less has been efficiently produced in large quantities. In such an ultra-low carbon steel, although the elongation is improved, the crystal grains of the hot-rolled sheet are apt to be coarsened, which deteriorates the deep drawability after cold rolling and annealing. In order to obtain the value, it is important to develop a technique for reducing the crystal grain size of the hot rolled sheet.
【０００４】[0004]
【従来の技術】これまで、深絞り性のよい鋼板を、Ｃが
0.005 mass％以下の鋼から製造する方法は既に知られて
いる。例えば、特開昭61-276930 号公報（伸びと深絞り
性の良好な極低炭素鋼冷延鋼板の製造方法）には、成分
組成を調整した極低炭素Ti, Nb複合添加鋼を、熱間圧延
条件、冷却条件、巻取り条件、冷間圧延条件および焼鈍
条件を適当に組合わせて、伸びと深絞り性の良好な冷延
鋼板を製造する方法が提案開示されている。2. Description of the Related Art Up to now, C
A method of manufacturing from steel of 0.005 mass% or less is already known. For example, in Japanese Patent Laid-Open No. 61-276930 (a method for producing a cold-rolled ultra-low carbon steel sheet with good elongation and deep drawability), an ultra-low carbon Ti, Nb composite-added steel whose composition has been adjusted is used. A method for producing a cold-rolled steel sheet having good elongation and deep drawability by appropriately combining cold rolling conditions, cooling conditions, winding conditions, cold rolling conditions and annealing conditions has been proposed and disclosed.
【０００５】すなわち、この方法は熱間延圧延直後に冷
却を開始し、γ粒の成長を抑制してα変態をさせること
によって熱延板の組織を微細化し、深絞り性に優れる冷
延鋼板を製造するものであり、その特徴とする点は平均
冷却速度を特定することにある。That is, according to this method, cooling is started immediately after hot-rolling, the growth of γ grains is suppressed and α-transformation is performed, whereby the structure of the hot-rolled sheet is refined and the cold-rolled steel sheet excellent in deep drawability is obtained. Is manufactured, and its characteristic point is to specify the average cooling rate.
【０００６】しかしながら、この方法では、平均冷却速
度：10℃／ｓ以上で熱延板を冷却するが、その冷却速度
は下限の限定以外に格別の記載がなく、したがって10℃
／ｓ以上とは、たとえばその実施例の30℃／ｓ程度と見
られ、この方法によって得られる熱延板のα粒径の微細
化には限界があり、その実施例の平均ｒ値も1.96〜2.28
の範囲にあってより高い深絞り性を有する冷延鋼板を製
造することが困難である。However, according to this method, the hot-rolled sheet is cooled at an average cooling rate of 10 ° C./s or more, but the cooling rate is not specifically described except for the lower limit, and therefore 10 ° C.
/ S or more is considered to be, for example, about 30 ° C./s in that example, and there is a limit to refining the α grain size of the hot rolled sheet obtained by this method, and the average r value of that example is 1.96. ~ 2.28
It is difficult to manufacture a cold-rolled steel sheet having a higher deep drawability in the range of.
【０００７】また、この方法では、詳細説明文中にｒ値
の面内異方性（Δｒ値）に関する記述があるもののその
値はΔｒ＝ 0.2〜0.4 と大きくより一層の向上が求めら
れるものである。なお、その実施例にはΔｒ値に関する
記述はない。Further, according to this method, although there is a description about the in-plane anisotropy (Δr value) of the r value in the detailed explanation, the value is as large as Δr = 0.2 to 0.4 and further improvement is required. . In addition, there is no description about the Δr value in the embodiment.
【０００８】さらなる深絞り性に優れる冷延鋼板を製造
するためには、深絞り性の向上に有効であることが知ら
れているＣをさらに低減する方法が考えられる。しか
し、鋼中のＣを低減すればするほど熱間圧延後の熱延板
に粗大な結晶粒が生成するようになり、この粗大な結晶
粒が冷延板の深絞り性を逆に低下させることになり、さ
らなる深絞り性の向上を達成することができなかった。In order to produce a cold-rolled steel sheet which is further excellent in deep drawability, a method of further reducing C, which is known to be effective in improving deep drawability, can be considered. However, as C in the steel is reduced, coarser crystal grains are generated in the hot-rolled sheet after hot rolling, and the coarser crystal grains conversely reduce the deep drawability of the cold-rolled sheet. As a result, it was not possible to further improve the deep drawability.
【０００９】このような、低レベルの極低炭素鋼を用い
る手段として、例えば、特開平１−177322号公報（極め
て深絞り性に優れる冷延鋼板の製造方法）には、Ｃ≦15
wtppm の極低炭素鋼を熱間圧延後、急冷することによ
り、深絞り性に優れる冷延鋼板を製造する方法が提案開
示されている。この方法は、熱間圧延後の冷却速度を 1
10〜400 ℃／ｓとすることで、γ粒の成長、回復を抑制
し細粒のα粒を生成させることを骨子としている。As means for using such a low-level ultra-low carbon steel, for example, Japanese Patent Laid-Open No. 1-177322 (a method for producing a cold-rolled steel sheet having extremely excellent deep drawability) has C ≦ 15.
A method for producing a cold-rolled steel sheet having excellent deep drawability is proposed and disclosed by hot-rolling wtppm ultra-low carbon steel and then quenching. This method reduces the cooling rate after hot rolling to 1
The main idea is to control the growth and recovery of γ-grains and generate fine α-grains at a temperature of 10 to 400 ° C./s.
【００１０】しかしながら、Ｃ≦15wt ppmとして、さら
にSi, Mn, ＰおよびＳなどの含有量もかなり低減してい
るため、γ粒の成長、回復はかなり速く、熱延後の急冷
だけでは結晶粒の微細化は十分でなく、その実施例から
ｒ値は2.48が最高であり、それ以上の深絞り性の向上は
できない。また、この手段では、ｒ値の面内異方性につ
いては、何らその記述がない。なお、実際のプレス成形
においては、面内異方性（Δｒ値）が小さい方がプレス
割れが減少することなどから、成形性の向上にはΔｒ値
を小さくすることも重要である。However, since C ≦ 15 wt ppm, the contents of Si, Mn, P, and S are considerably reduced, so that the growth and recovery of γ grains are fairly fast, and the crystal grains can be obtained only by rapid cooling after hot rolling. Is not sufficient, and the r value of 2.48 is the highest from that example, and further deep drawability cannot be improved. Further, in this means, there is no description about the in-plane anisotropy of the r value. In actual press molding, the smaller the in-plane anisotropy (Δr value) is, the more the press cracks are reduced. Therefore, it is also important to reduce the Δr value in order to improve the formability.
【００１１】以上より、平均ｒ値をより高くし、Δｒ値
をより低くすることの要請に対し、上記２例を含む従来
技術では、未だ十分に対応できないという問題があっ
た。From the above, there is a problem that the prior art including the above-mentioned two examples cannot sufficiently meet the demand for higher average r value and lower Δr value.
【００１２】[0012]
【発明が解決しようとする課題】この発明は、前記した
問題を有利に解決しようとするもので、鋼の成分組成お
よび製造条件を規制することにより、良好な焼付け硬化
性を有するとともに従来よりも格段に優れる深絞り性お
よび面内異方性を有する冷延鋼板の製造方法を提案する
ことを目的とする。DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems advantageously, and has good bake hardenability and better than conventional ones by regulating the composition of steel and the manufacturing conditions. It is an object of the present invention to propose a method for manufacturing a cold-rolled steel sheet having markedly excellent deep drawability and in-plane anisotropy.
【００１３】[0013]
【課題を解決するための手段】この発明は、発明者ら
が、加工性のさらなる向上を目的として鋭意研究を重ね
た結果、鋼の成分組成および熱延条件を主とする製造条
件を限定することにより、優れる面内異方性および深絞
り性を有する焼付硬化型冷延鋼板の製造が可能であるこ
とを見出したことによるものである。As a result of intensive studies conducted by the inventors for the purpose of further improving the workability of the present invention, the present invention limits the production conditions mainly on the composition of the steel and hot rolling conditions. This is due to the finding that it is possible to manufacture a bake hardened cold rolled steel sheet having excellent in-plane anisotropy and deep drawability.
【００１４】すなわち、この発明の要旨とするところは
以下の通りである。 Ｃ：0.0010mass％以下、Si：0.1 mass％以下、Mn：0.3
mass％以下、Nb：0.03mass％以下、Ｂ：0.0001〜0.0030
mass％以下、Al：0.1 mass％以下、Ｐ：0.05mass％以
下、Ｓ：0.005 mass％以下およびＮ：0.003 mass％以
下、を含有し、かつ １≦Nb（mass％）／Ｃ（mass％）≦30および Ｎ（mass％）−14／11・Ｂ（mass％）≦ 0.001（mass
％） の関係を満たし、残部は鉄および不可避的不純物の組成
になる鋼スラブを素材として、仕上げ圧延出側３パスで
の累積圧下率を50％以上とする熱間圧延を行い、Ar3 変
態点以上の温度で仕上げ圧延を終了したのち、0.5 秒間
以内に冷却を開始し、Ar3 変態点以上の冷却開始温度か
らAr3 変態点−60℃までの温度域を70〜400 ℃／ｓの範
囲の冷却速度で冷却したのち、 550〜800 ℃の温度範囲
でコイルに巻取り、その後通常の方法で冷間圧延し、連
続焼鈍を施すことを特徴とする成形性に優れる焼付硬化
型冷延鋼板の製造方法である。That is, the gist of the present invention is as follows. C: 0.0010 mass% or less, Si: 0.1 mass% or less, Mn: 0.3
mass% or less, Nb: 0.03 mass% or less, B: 0.0001 to 0.0030
mass% or less, Al: 0.1 mass% or less, P: 0.05 mass% or less, S: 0.005 mass% or less and N: 0.003 mass% or less, and 1 ≦ Nb (mass%) / C (mass%) ≤30 and N (mass%)-14/11 ・ B (mass%) ≤ 0.001 (mass
%) And the balance is iron and inevitable impurities in the steel slab. Hot rolling with cumulative rolling reduction of 50% or more in the 3rd pass of finish rolling is performed, and Ar 3 transformation is performed. After completion of the finish rolling at a point above the temperature to start cooling within 0.5 seconds, the Ar 3 transformation point or more cooling start temperature the temperature range of up to Ar 3 transformation point -60 ° C. of 70 to 400 ° C. / s After being cooled at a cooling rate in the range, it is wound into a coil in the temperature range of 550 to 800 ° C, then cold rolled by the usual method and subjected to continuous annealing, which is a bake hardening type cold rolling with excellent formability. It is a method of manufacturing a steel sheet.
【００１５】[0015]
【作用】この発明の作用について以下に述べる。まず、
この発明の基礎となった実験例について述べる。 Ｃ：0.0008mass％、Si：0.008 mass％、Mn：0.1 mass
％、Nb：0.01mass％、Ｂ：0.0015mass％、Al：0.05mass
％、Ｐ：0.012 mass％、Ｓ：0.001 mass％およびＮ：0.
0018mass％の組成になる鋼スラブを1150℃の温度に加熱
し均熱したのち、熱間圧延を施し仕上げ圧延出側３パス
の累積圧下率を変化させ、それぞれ 920℃の温度で仕上
げ圧延を終了し、0.3 秒間後に冷却速度を変えて 860℃
の温度まで冷却した各熱延板をそれぞれ 750℃の温度で
コイルに巻き取った。その後これらの熱延板に、それぞ
れ圧下率：80％の冷間圧延を施したのち、860 ℃の温度
で20秒間の再結晶焼鈍を行った。The operation of the present invention will be described below. First,
An experimental example which is the basis of the present invention will be described. C: 0.0008 mass%, Si: 0.008 mass%, Mn: 0.1 mass
%, Nb: 0.01 mass%, B: 0.0015 mass%, Al: 0.05 mass
%, P: 0.012 mass%, S: 0.001 mass% and N: 0.
A steel slab having a composition of mass% is heated to a temperature of 1150 ° C and soaked, and then hot-rolled to change the cumulative rolling reduction of the finishing rolling 3 passes, and finish rolling is finished at a temperature of 920 ° C. After 0.3 seconds, change the cooling rate to 860 ℃.
Each hot-rolled sheet cooled to the temperature of was coiled at a temperature of 750 ° C. Thereafter, each of these hot-rolled sheets was cold-rolled at a rolling reduction of 80%, and then recrystallized and annealed at a temperature of 860 ° C. for 20 seconds.
【００１６】かくして得られた各熱延板の結晶粒径、冷
間圧延−焼鈍後の各鋼板について平均ｒ値およびΔｒ値
を調査した。これらの調査結果の一部を図１および図２
に示す。The crystal grain size of each hot-rolled sheet thus obtained, and the average r value and Δr value of each steel sheet after cold rolling-annealing were investigated. Some of these survey results are shown in Figure 1 and Figure 2.
Shown in
【００１７】図１は、冷間圧延−焼鈍後の鋼板の平均ｒ
値におよぼす仕上げ圧延出側３パスの累積圧下率および
熱間圧延後の冷却速度の影響を示すグラフであり、図２
は、冷間圧延−焼鈍後の鋼板のΔｒ値におよぼす仕上げ
圧延出側３パスの累積圧下率および熱間圧延後の冷却速
度の影響を示すグラフである。FIG. 1 shows the average r of the steel sheet after cold rolling and annealing.
2 is a graph showing the influence of the cumulative rolling reduction on the 3rd pass of the finishing rolling and the cooling rate after hot rolling on the value.
[Fig. 6] is a graph showing the influence of the cumulative reduction ratio of the three passes on the finishing rolling exit side and the cooling rate after hot rolling on the Δr value of the steel sheet after cold rolling-annealing.
【００１８】ここに、平均ｒ値は、JIS ５号引張試験片
を使用し、15％の予歪を与えたのちち３点法により測定
し、Ｌ方向（圧延方向：ｒL ）、Ｄ方向（圧延方向に対
し45°方向：ｒD ）およびＣ方向（圧延方向に対し90°
方向：ｒC ）の平均値として下記式から求めた。 平均ｒ値＝（ｒL ＋２ｒD ＋ｒC ）／４ また、面内異方性Δｒ値は Δｒ値＝（ｒL −２ｒD ＋ｒC ）／２ から求めた。Here, the average r value is measured by using a JIS No. 5 tensile test piece, pre-strained with 15%, and then measured by the three-point method, and the L direction (rolling direction: r L ) and the D direction. (45 ° to rolling direction: r D ) and C direction (90 ° to rolling direction)
The average value of the direction: r C ) was calculated from the following formula. Average r value = (r L + 2r D + r C ) / 4 The in-plane anisotropy Δr value was calculated from Δr value = (r L −2r D + r C ) / 2.
【００１９】図１および図２を含め上記実験結果より、
冷間圧延−焼鈍後の鋼板の平均ｒ値は、仕上げ圧延時の
圧下率および熱間圧延後の冷却速度に依存し、仕上げ圧
延での出側３パスの累積圧下率を50％以上としかつ熱間
圧延後の冷却速度を速くする（具体的には70〜400 ℃／
ｓ）ことにより、熱延板の結晶粒径の微細化がはかられ
高い平均ｒ値が得られることがわかった。また、Δｒ値
は、同様に仕上げ圧延出側３パスでの累積圧下率を50％
以上とし冷却速度を速くする（70〜400 ℃／ｓ）ことに
より 0.2未満と極めて小さくなることがわかった。発明
者らは、以上の実験結果をもとにさらに研究を重ねた結
果この発明を達成したもので、その限定理由を以下に順
にのべる。From the above experimental results including FIG. 1 and FIG.
The average r value of the steel sheet after cold rolling-annealing depends on the reduction rate during finish rolling and the cooling rate after hot rolling, and the cumulative reduction rate of the exit side 3 passes in finish rolling is set to 50% or more. Increase the cooling rate after hot rolling (specifically 70 to 400 ° C /
By s), it was found that the crystal grain size of the hot rolled sheet was reduced and a high average r value was obtained. Similarly, the Δr value is the cumulative rolling reduction of 50% on the 3rd pass of finishing rolling.
It was found that by increasing the cooling rate (70 to 400 ° C / s), the value was less than 0.2, which was extremely small. The inventors have achieved the present invention as a result of further research based on the above experimental results, and the reasons for limitation are listed below.
【００２０】１）成分組成 Ｃ：0.0010mass％以下 Ｃは、少なければ少ないほど深絞り性および延性が向上
するので好ましく、さらに、Ｃが低いほうがこれを固定
するためのNbの添加量や生成する炭化物量も少なくなる
ため、極めて優れる深絞り性を得ることができる。した
がって、その含有量は近年の精錬技術で容易に達成で
き、かつ許容できる値として0.0010mass％を上限とす
る。1) Component composition C: 0.0010 mass% or less C is preferable because the smaller the content, the better the deep drawability and ductility, and the lower the content of C, the more the amount of Nb added to fix it and the more it forms. Since the amount of carbides is also small, it is possible to obtain extremely excellent deep drawability. Therefore, the upper limit of the content is 0.0010 mass% as an acceptable value that can be easily achieved by recent refining technology.
【００２１】Si：0.1 mass％以下 Siは、鋼を硬化させる作用があり、所望の強度に応じて
必要量含有させるが、その含有量が 0.1mass％を超える
と深絞り性および表面性状に悪影響を与える。したがっ
て、その含有量は 0.1mass％以下とする。Si: 0.1 mass% or less Si has the effect of hardening the steel, and is contained in a required amount according to the desired strength. If the content exceeds 0.1 mass%, deep drawability and surface properties are adversely affected. give. Therefore, its content should be 0.1 mass% or less.
【００２２】Mn：0.3 mass％以下 Mnは、鋼の溶製上、脱酸成分として重要であるが、過剰
に含有させると鋼を脆化させたり、深絞り性に悪影響を
与える。したがって、その含有量は 0.3mass％以下とす
る。Mn: 0.3 mass% or less Mn is important as a deoxidizing component in the melting of steel, but if it is contained in excess, it embrittles the steel and adversely affects deep drawability. Therefore, its content should be 0.3 mass% or less.
【００２３】Nb：0.03mass％以下 Nbは、鋼中の固溶Ｃを炭化物として析出固定させて低減
し、良好なプレス成形性を得るために添加する。その効
果は含有量が0.03mass％以下で十分であり、0.03mass％
を超えて含有させてもそれ以上の効果は得られず、逆に
再結晶温度の上昇や延性の劣化につながる。したがっ
て、その含有量は0.03mass％以下とする。Nb: 0.03 mass% or less Nb is added in order to precipitate and fix the solid solution C in the steel as a carbide to reduce it and to obtain good press formability. The effect is sufficient if the content is 0.03 mass% or less, 0.03 mass%
If it is contained in an amount exceeding the above range, no further effect can be obtained, and on the contrary, the recrystallization temperature rises and the ductility deteriorates. Therefore, the content is 0.03 mass% or less.
【００２４】Ｂ：0.0001〜0.0030mass％ Ｂは、鋼中の固溶Ｎを窒化物として析出固定させて低減
し、良好なプレス成形性を得るために添加する。含有量
が0.0001mass％未満ではその効果がなく、一方0.0030ma
ss％を超えて添加してもそれ以上の効果は得られなく逆
に深絞り性が劣化する。したがって、その含有量は0.00
01mass％以上、0.0030mass％以下とする。B: 0.0001 to 0.0030 mass% B is added in order to precipitate and fix the solid solution N in the steel as a nitride to reduce it and to obtain good press formability. If the content is less than 0.0001mass%, there is no effect, while 0.0030ma
Even if added in excess of ss%, no further effect is obtained and conversely the deep drawability deteriorates. Therefore, its content is 0.00
It should be more than 01mass% and less than 0.0030mass%.
【００２５】Al：0.1 mass％以下 Alは、溶鋼を脱酸してNbの歩留りを向上させるとともに
鋼中の固溶Ｎを固定させるために添加する。しかし含有
量が0.1 mass％を超えて含有させるとプレス成形性を損
なう。したがって、その含有量は0.1 mass％以下とす
る。Al: 0.1 mass% or less Al is added to deoxidize the molten steel to improve the yield of Nb and to fix the solid solution N in the steel. However, if the content exceeds 0.1 mass%, press formability is impaired. Therefore, its content should be 0.1 mass% or less.
【００２６】Ｐ：0.05mass％以下 Ｐは、鋼を強化する作用があり、所望の強度に応じて必
要量添加するが、その含有量が0.05mass％を超えると深
絞り性、脆性に悪影響をおよぼす。したがって、その含
有量は0.05mass％以下とする。P: 0.05 mass% or less P has the effect of strengthening the steel and is added in the required amount according to the desired strength. If the content exceeds 0.05 mass%, deep drawability and brittleness are adversely affected. Extend. Therefore, its content should be 0.05 mass% or less.
【００２７】Ｓ：0.005 mass％以下 Ｓは、Mnと結合して MnSを形成し析出する。多量にMnS
が析出すると鋼が硬化し、プレス成形性を低下させる。
したがって、その含有量は少なければ少ないほど好まし
いが、許容できる上限を0.005 mass％とする。S: 0.005 mass% or less S combines with Mn to form MnS and precipitates. Large amount of MnS
When is precipitated, the steel is hardened and the press formability is reduced.
Therefore, the smaller the content, the better, but the allowable upper limit is 0.005 mass%.
【００２８】Ｎ：0.003 mass％以下 Ｎは、少なければ少ないほど深絞り性が向上し、Ｂの添
加量も少なくてすむ。良好な加工性を得るためその含有
量は0.003 mass％以下とするが、より一層の深絞り性の
向上のためには0.002 mass％以下とすることが好まし
い。さらに、この発明においては上記含有量の範囲内に
おいて、ＣとNbとの関係およびＢとＮとの関係をそれぞ
れ以下のように限定する。N: 0.003 mass% or less The smaller the content of N, the better the deep drawability and the smaller the amount of B added. The content is 0.003 mass% or less in order to obtain good workability, but it is preferably 0.002 mass% or less in order to further improve the deep drawability. Further, in the present invention, within the above range of content, the relationship between C and Nb and the relationship between B and N are limited as follows.
【００２９】１≦Nb（mass％）／Ｃ（mass％）≦30 この発明において、NbとＣとの比は良加工性を有しかつ
焼付硬化性を確保するために極めて重要である。Nb／Ｃ
が30を超えると含有するＣがほとんどNbにより析出固定
されて固溶Ｃがなくなり、この発明の特徴である焼付硬
化性すなわちＢＨ量が極端に低下してしまい焼付後に安
定した硬度が得られなくなる。逆にNb／Ｃが１未満では
固溶Ｃが多量に残存し、加工性が劣化する。したがって
NbとＣとの比は、１≦Nb（mass％）／Ｃ（mass％）≦30
とするが、好ましくは８≦Nb（mass％）／Ｃ（mass％）
≦25とすることが望ましい。1 ≦ Nb (mass%) / C (mass%) ≦ 30 In the present invention, the ratio of Nb and C is extremely important for good workability and ensuring bake hardenability. Nb / C
When the ratio exceeds 30, most of the contained C is precipitated and fixed by Nb and solid solution C disappears, and the bake hardenability, that is, the BH amount, which is a feature of the present invention, is extremely lowered, and stable hardness cannot be obtained after baking. . On the other hand, if Nb / C is less than 1, a large amount of solute C remains and the workability deteriorates. Therefore
The ratio of Nb and C is 1 ≦ Nb (mass%) / C (mass%) ≦ 30
However, preferably 8 ≦ Nb (mass%) / C (mass%)
It is desirable that ≦ 25.
【００３０】Ｎ（mass％）−14／11・Ｂ（mass％）≦0.
001 （mass％） 極低Ｃ化、極低Ｓ化ともにＮを低減することが良加工性
を得るために重要である。すなわち、ＮをＢにより析出
固定させることにより平均ｒ値の向上に有効な再結晶集
合組織が得られる。このためＮ（mass％）−14／11・Ｂ
（mass％）を0.001 （mass％）以上とする。N (mass%)-14 / 11.B (mass%) ≤0.
001 (mass%) In order to obtain good workability, it is important to reduce N in both extremely low C and extremely low S. That is, by precipitating and fixing N with B, a recrystallization texture effective for improving the average r value can be obtained. Therefore, N (mass%)-14/11 ・ B
(Mass%) should be 0.001 (mass%) or more.
【００３１】２）製造工程 ・熱間圧延 熱間圧延工程での圧延条件およびその後の冷却条件はこ
の発明において極めて重要であり、粗圧延終了後仕上げ
圧延の最終３パスでの累積圧下率が50％以上の圧延を行
い、Ar3 変態点以上で熱間圧延を終了したのち 0.5秒間
以内に冷却を開始し、Ar3 変態点以上の冷却開始温度か
らAr3 変態点−60℃の温度域を70〜400℃／ｓの範囲の
冷却速度で冷却することが必要である。2) Manufacturing Process-Hot Rolling The rolling conditions in the hot rolling process and the subsequent cooling conditions are extremely important in the present invention, and the cumulative rolling reduction in the final three passes of the finishing rolling after the completion of rough rolling is 50. % perform more rolling, to start cooling within 0.5 seconds after the completion of the hot rolling at Ar 3 transformation point or more, the temperature range of Ar 3 transformation point -60 ° C. from Ar 3 transformation point or more cooling start temperature It is necessary to cool at a cooling rate in the range of 70 to 400 ° C / s.
【００３２】鋼スラブの加熱、粗圧延、仕上げ圧延、冷
却およびコイルへの巻取りに至る熱延板の製造プロセス
での金属組織変化は、鋼スラブ加熱時の粗大オーステナ
イト（γ）粒が粗圧延、仕上げ圧延中に加工−再結晶を
繰り返しながら細粒化され、その後の冷却過程で細粒γ
からフェライト（α）を主体とする組織に変態する。こ
の再結晶γ粒からのγ→α変態はγ粒界へのα核生成に
はじまり、そのα核の成長が進行し、それぞれのα粒が
ぶつかりあって終了する。したがって、γ粒が小さいほ
どα核の生成箇所が多くなり、ぶつかり合うまでの距離
が短くなるため、α粒は細かくなる。The metallographic structure change in the manufacturing process of the hot rolled sheet including heating, rough rolling, finish rolling, cooling of the steel slab and winding into a coil is caused by coarse rolling of coarse austenite (γ) grains during heating of the steel slab. During the finishing rolling, it is refined by repeating working-recrystallization, and in the subsequent cooling process, fine grains γ
To a structure mainly composed of ferrite (α). The γ → α transformation from the recrystallized γ grains starts with α nucleation at the γ grain boundary, the growth of the α nuclei proceeds, and the α grains collide with each other to end. Therefore, the smaller the γ grains, the more the α nuclei are generated, and the shorter the distance until the collision occurs, so the α grains become finer.
【００３３】仕上げ圧延後段では圧延材温度が低くなる
ため圧延直後のγ粒は再結晶が比較的起こりにくく、加
工されたままの状態を維持しやすくなる。このような加
工γ粒は再結晶γ粒に比し、伸ばされた形状になってい
るため、粒の単位体積当りの粒界面積は大きくなりα核
生成箇所が多くなる。さらに、加工γ粒内には変形帯と
呼ばれる加工歪を蓄積した組織が形成され、これがα核
の生成箇所となる。したがって、加工γ粒は再結晶γ粒
に比し格段にα核生成箇所が多いため、加工γ粒から変
態したα粒の数は多く、再結晶γ粒から変態したαより
も細かくなる。Since the temperature of the rolled material becomes lower in the latter stage of finish rolling, recrystallization of γ grains immediately after rolling is relatively unlikely to occur, and it is easy to maintain the as-processed state. Since such processed γ-grains have a stretched shape as compared with recrystallized γ-grains, the grain boundary area per unit volume of the grain becomes large and the α-nucleation sites increase. Furthermore, a structure called a deformation zone, in which processing strains are accumulated, is formed in the processed γ grains, and this is the generation site of α nuclei. Therefore, since the processed γ-grains have much more α-nucleation sites than the recrystallized γ-grains, the number of α-grains transformed from the processed γ-grains is large, and the α-grains transformed from the recrystallized γ-grains are finer.
【００３４】この発明の最大のポイントは、上記の加工
γ粒を多量に蓄積・残存させ、この加工γ粒からの変態
を利用してα粒の細粒化をはかる点にある。すなわち、
通常の熱間圧延プロセスでは圧延温度の高い仕上げ圧延
前段での圧下率を大きくし、その後段では形状補正や板
厚の微調整を施すため圧下率を小さくしている。したが
って、圧延温度が高い圧延前段で圧下率の大きい加工を
受けてもその加工γ粒の再結晶の進行は早く圧延後段で
は圧下率が小さいため圧延終了時での加工γ粒は少量し
か蓄積されないことになる。The greatest point of the present invention is that a large amount of the processed γ-grains are accumulated / remained and the α-grains are refined by utilizing the transformation from the processed γ-grains. That is,
In the normal hot rolling process, the reduction ratio is increased in the first stage of finish rolling where the rolling temperature is high, and in the subsequent stage, the reduction ratio is reduced to perform shape correction and fine adjustment of the plate thickness. Therefore, even if a rolling process with a high rolling temperature with a high rolling temperature undergoes a large reduction, the recrystallization of the processed γ grains progresses quickly, and since the rolling ratio is small in the post rolling stage, only a small amount of the processed γ grains accumulate at the end of rolling. It will be.
【００３５】しかも、仕上げ圧延出側から水冷設備まで
の非水冷ゾーンが数秒間あるため、その間に加工γ粒の
再結晶ならびに回復（加工歪・変形帯の消失）が進行し
加工γ粒からのα変態はほとんど期待できなくなる。Moreover, since there is a non-water cooling zone from the exit side of the finish rolling to the water cooling equipment for several seconds, recrystallization and recovery of the processed γ grains (disappearance of processing strain / deformation zone) progresses during that time, and Almost no alpha transformation can be expected.
【００３６】これに対しこの発明においては、圧延温度
の低い仕上げ圧延後段で圧下率を大きくすることによっ
て、多量の加工γ粒を蓄積させ、さらに仕上げ圧延後短
時間内に冷却を開始して熱延板温度を低下させγ域の帯
留時間を短縮することによって、加工γ粒の再結晶なら
びに回復を僅少にとどめ、多量の加工γ粒を残存させた
ままα変態をさせることができる。したがって、従来に
ないα粒の細粒化が可能になる。On the other hand, in the present invention, a large amount of processed γ-grains is accumulated by increasing the rolling reduction in the latter stage of finish rolling at a low rolling temperature, and further, cooling is started within a short time after finish rolling to perform heat treatment. By lowering the temperature of the rolled sheet and shortening the retention time in the γ region, recrystallization and recovery of the processed γ grains can be minimized, and the α transformation can be performed while leaving a large amount of the processed γ grains. Therefore, it becomes possible to make α grains finer than ever before.
【００３７】仕上げ圧延終了温度は、Ar3 変態点以下で
は熱延板に粗大粒が発生したり、一般に云われている加
工組織が残留したりして、冷間圧延・焼鈍後の深絞り性
を損なうのでAr3 変態点以上とする。そして、仕上げ圧
延終了後Ar3 変態点以上の適当な温度から冷却を開始す
る。すなわち、冷却開始時期は、仕上げ圧延後 0.5秒間
以内であれば仕上げ圧延直後でなくてもよく、ランナウ
トテーブルの適当な位置で冷却を開始できる。したがっ
て、仕上げ圧延機の出側に板厚計や温度計が配置されて
いる通常の圧延機でも、冷却による水蒸気などの影響を
受けることなく圧延材の板厚や温度の計測、管理、制御
が可能である。When the finish rolling finish temperature is below the Ar 3 transformation point, coarse grains are generated in the hot-rolled sheet or the generally known worked structure remains, so that deep drawability after cold rolling / annealing occurs. Therefore, the Ar 3 transformation point or higher is set. Then, after finishing rolling is finished, cooling is started from an appropriate temperature above the Ar 3 transformation point. That is, the cooling start time may not be immediately after finish rolling as long as it is within 0.5 seconds after finish rolling, and cooling can be started at an appropriate position on the runout table. Therefore, even with a normal rolling mill that has a strip thickness gauge and a thermometer on the exit side of the finishing rolling mill, it is possible to measure, manage, and control the strip thickness and temperature of the rolled material without being affected by steam or the like due to cooling. It is possible.
【００３８】ついで、仕上げ圧延後 0.5秒間以内で開始
する冷却は、Ar3 変態点以上の温度からAr3 変態点−60
℃以下の温度で行い、その冷却速度はAr3 変態点以上の
冷却開始温度からAr3 変態点−60℃までの温度域を70〜
400 ℃／ｓの範囲とする。この冷却方法を、上記の仕上
げ圧延の後段で圧下率を大きくし強圧下で仕上げた熱延
材に適用することによってα粗の微細化ひいては冷間圧
延・焼鈍後の鋼板の加工性を極めて優れたものとするこ
とを可能にする。[0038] Next, cooling starts within 0.5 second after the finish rolling, Ar 3 transformation point -60 from Ar 3 transformation point or more of the temperature
° C. performed at a temperature below the cooling rate is 70 to the temperature range of from Ar 3 transformation point or more of the cooling start temperature to Ar 3 transformation point -60 ° C.
The range is 400 ° C / s. By applying this cooling method to the hot-rolled material that has a higher reduction ratio in the latter stage of the above finish rolling and is finished under high pressure, α coarseness is refined, and by extension, the workability of the steel sheet after cold rolling / annealing is extremely excellent. Make it possible.
【００３９】すなわち仕上げ圧延後冷却条件のみを規定
した従来法（例えば特開平１−177322号公報）による冷
間圧延・焼鈍後の鋼板では、平均ｒ値が最高で 2.5であ
ったのに対し、仕上げ圧延での最終３パスの累積圧下率
を50％以上とし、上記冷却方法を適用したこの発明の冷
間圧延・焼鈍後の鋼板では 2.7以上の平均ｒ値を得るこ
とが容易であり、また、面内異方性においても、特開昭
61-276930 号公報ではΔｒ値が 0.2〜0.4 であったのに
対し、この発明によれば、0.2 未満の極めて小さいΔｒ
値を得ることができ、平均ｒ値のみならず面内異方性も
特段に優れるものとなる。That is, in the steel sheet after cold rolling / annealing according to the conventional method (for example, Japanese Patent Laid-Open No. 1-177322) in which only the cooling conditions after finish rolling are specified, the average r value was 2.5 at the maximum. It is easy to obtain an average r value of 2.7 or more in the steel sheet after cold rolling / annealing of the present invention in which the cumulative rolling ratio of the final three passes in finish rolling is 50% or more and the above cooling method is applied. Also in the in-plane anisotropy,
In the 61-276930 publication, the Δr value was 0.2 to 0.4, whereas according to the present invention, the extremely small Δr of less than 0.2.
The value can be obtained, and not only the average r value but also the in-plane anisotropy becomes particularly excellent.
【００４０】なお、仕上げ圧延後時間をおいて（0.5 秒
超え）Ar3 変態点以下の温度から冷却を開始したり、冷
却速度を70℃／ｓ未満とすると、γ域での滞留時間が長
くなり、その間にγ粒は再結晶および回復（変形帯の消
失）が進行してしまい加工γ粒からの変態が期待できな
くなる。したがって、仕上げ圧延後 0.5秒間以内に冷却
を開始し冷却速度を70℃／ｓ以上とすることにより加工
γ粒は加工状態（圧延歪を蓄積した変形帯を有する状
態）を維持でき、その後のγ→α変態によるα粒の微細
化がはかれることになる。If the cooling is started at a temperature below the Ar 3 transformation point with a time after finish rolling (more than 0.5 seconds) or the cooling rate is less than 70 ° C./s, the residence time in the γ region becomes long. During that time, the γ-grains undergo recrystallization and recovery (disappearance of the deformation zone), and transformation from the processed γ-grains cannot be expected. Therefore, by starting cooling within 0.5 seconds after finish rolling and setting the cooling rate to 70 ° C / s or more, the processed γ grains can maintain the processed state (the state having the deformation zone accumulating rolling strain), and → The α grains will be refined by α transformation.
【００４１】このとき、その冷却装置は、Ar3 変態点以
上の温度から冷却を開始するため、通常の仕上げ圧延機
の出側に配置されている板厚計や温度計の作動に支障を
与えない範囲で、仕上げ圧延機にできるだけ近づけて配
置することが望ましい。また、その冷却媒体としては
水、気体およびそれらの混合体などいずれでもよい。At this time, since the cooling device starts cooling from the temperature of the Ar 3 transformation point or higher, it interferes with the operation of the plate thickness gauge and the thermometer arranged on the exit side of the usual finish rolling mill. It is desirable to place it as close as possible to the finish rolling mill within the range that does not exist. Further, the cooling medium may be any of water, gas and a mixture thereof.
【００４２】・巻取り温度 熱延板のコイル巻取り温度は、AlN , BNおよびMnS など
の析出物を十分に析出させ、さらにその析出物を成長粗
大化させるために重要である。巻取り温度は550 ℃以上
であれば固溶Ｎ, 固溶Ｓを十分析出固定させることがで
きる。一方巻取り温度が 800℃を超えるとスケールが厚
く生成し酸洗性が低下する。したがって、熱延板のコイ
ル巻取り温度は 550〜800 ℃の範囲とする。Winding temperature The coil winding temperature of the hot-rolled sheet is important for sufficiently depositing precipitates such as AlN, BN and MnS, and further for growing and coarsening the precipitates. If the winding temperature is 550 ° C. or higher, solid solution N and solid solution S can be sufficiently deposited and fixed. On the other hand, when the winding temperature exceeds 800 ° C, the scale is thick and the pickling property deteriorates. Therefore, the coil winding temperature of the hot-rolled sheet shall be in the range of 550-800 ℃.
【００４３】なお、鋼スラブの加熱温度は特に規定する
ものではないが、1000〜1300℃の温度範囲とすれば最終
的に良好な品質の冷延鋼板を得ることができる。また、
鋼スラブには、連続鋳造したものを直ちに用いても、一
たん冷却したものを用いてもいずれでもよい。The heating temperature of the steel slab is not particularly specified, but if the temperature range is 1000 to 1300 ° C., a cold rolled steel sheet of good quality can be finally obtained. Also,
The steel slab may be either a continuously cast product or a cooled product.
【００４４】・冷間圧延 冷間圧延は特にその条件を規定するものではないが、圧
下率は50〜90％、望ましくは70〜90％の範囲とすること
が好ましく、かくすることにより特段に優れる加工性を
有する冷延鋼板が得られる。Cold Rolling Cold rolling does not particularly define the conditions, but it is preferable that the rolling reduction is in the range of 50 to 90%, desirably 70 to 90%. A cold rolled steel sheet having excellent workability can be obtained.
【００４５】・焼鈍 冷間圧延を経た冷延鋼帯は再結晶焼鈍を施す必要があ
る。焼鈍方法は、箱焼鈍法又は連続焼鈍法のいずれでも
よい。また、焼鈍温度は、あまりにも高い温度や再結晶
温度以下では不適で、700 〜950 ℃の通常常識の温度範
囲とすることが望ましい。Annealing The cold-rolled steel strip that has undergone cold rolling needs to be subjected to recrystallization annealing. The annealing method may be either a box annealing method or a continuous annealing method. Further, the annealing temperature is unsuitable at an excessively high temperature or below the recrystallization temperature, and it is desirable to set the temperature within a generally accepted temperature range of 700 to 950 ° C.
【００４６】なお、焼鈍後の鋼帯には形状矯正、表面粗
度等の調整のため、５％以下の調質圧延を加えてもよ
い。さらにこの発明の冷延鋼板は、亜鉛めっき（合金系
めっきを含む）、すずめっき、ほうろう、その他表面処
理鋼板の原板にも有利に適用できる。The annealed steel strip may be subjected to temper rolling of 5% or less in order to correct the shape and adjust the surface roughness. Furthermore, the cold-rolled steel sheet of the present invention can be advantageously applied to zinc plating (including alloy-based plating), tin plating, enamel, and other original sheets of surface-treated steel sheet.
【００４７】[0047]
【実施例】表１に示す種々の成分組成になる鋼スラブ
を、それぞれ表２に示す熱間圧延条件にて圧延し、得ら
れた熱延板を酸洗後、圧下率80％の冷間圧延を行い板
厚：0.7mm の冷延鋼帯としたのち、連続焼鈍設備にて温
度： 860℃、時間：20秒間の再結晶焼鈍を施し、圧下
率： 0.7％の調質圧延を施した。かくして得られた熱延
板での結晶粒度ならびに冷延板の平均ｒ値、Δｒ値など
について調査し、それらの結果を表２に併記した。[Examples] Steel slabs having various compositional compositions shown in Table 1 were rolled under hot rolling conditions shown in Table 2, respectively, and the hot-rolled sheets obtained were pickled and then cold-rolled at a rolling reduction of 80%. After rolling to make a cold-rolled steel strip with a thickness of 0.7 mm, it was subjected to recrystallization annealing at a temperature of 860 ° C for 20 seconds with continuous annealing equipment, and temper rolling with a rolling reduction of 0.7%. . The crystal grain size of the thus obtained hot-rolled sheet and the average r value, Δr value of the cold-rolled sheet were investigated, and the results are also shown in Table 2.
【００４８】[0048]
【表１】 [Table 1]
【００４９】[0049]
【表２】 [Table 2]
【００５０】なお、平均ｒ値、Δｒ値の測定方法は前記
実験例の場合と同様である。表２から明らかなように、
鋼の成分組成がこの発明に適合し、かつ、熱間圧延条件
等の製造条件がこの発明に適合する適合例は、良好な焼
付硬化性を有し、かつ、平均ｒ値が2.65〜3.15、Δｒ値
が0.19〜0.12と深絞り性および面内異方性に極めて優れ
る冷延鋼板が得られることが分かる。これらに対し、比
較例は焼付硬化性や深絞り性および面内異方性に劣って
いる。The method of measuring the average r value and Δr value is the same as in the case of the above experimental example. As is clear from Table 2,
The composition of the steel is compatible with the present invention, and the conforming example in which the manufacturing conditions such as hot rolling conditions are compatible with the present invention have good bake hardenability, and the average r value is 2.65 to 3.15, It can be seen that a cold rolled steel sheet having a Δr value of 0.19 to 0.12 and having extremely excellent deep drawability and in-plane anisotropy can be obtained. On the other hand, Comparative Examples are inferior in bake hardenability, deep drawability and in-plane anisotropy.
【００５１】また、表１に示した成分組成になる鋼スラ
ブを素材として、冷延鋼板を製造したのち、連続溶融亜
鉛めっきおよび連続電気亜鉛めっきラインにてそれぞれ
亜鉛めっきを施しためっき鋼板について、上記と同様の
調査を行った。これらの製造条件および調査結果を表３
にまとめて示す。Further, cold-rolled steel sheets were manufactured using steel slabs having the composition shown in Table 1 as raw materials, and galvanized steel sheets were respectively galvanized by continuous hot-dip galvanizing and continuous electrogalvanizing lines. The same survey as above was conducted. Table 3 shows the manufacturing conditions and survey results.
Are shown together.
【００５２】[0052]
【表３】 [Table 3]
【００５３】表３から明らかなように、この発明に適合
する条件で製造した適合例の冷延鋼板は、めっき後にお
いても良好な焼付硬化性を有するとともに、極めて優れ
る深絞り性および面内異方性を示している。As is clear from Table 3, the cold-rolled steel sheet of the conforming example manufactured under the conditions conforming to the present invention has good bake hardenability even after plating, and has extremely excellent deep drawability and in-plane anomaly. It shows the direction.
【００５４】[0054]
【発明の効果】この発明は、極低炭素鋼の成分組成を限
定し、さらに製造条件として特に熱間圧延とその後の冷
却条件を特定することにより、成形性に優れる焼付硬化
型冷延鋼板を製造するものであって、この発明によれ
ば、良好な焼付硬化性を有しかつ従来よりも格段に優れ
る深絞り性および面内異方性を有する冷延鋼板の製造が
可能となり、その鋼板は自動車用等の加工用鋼板として
極めて有利に適用できる。INDUSTRIAL APPLICABILITY The present invention provides a bake hardening type cold rolled steel sheet having excellent formability by limiting the composition of the composition of ultra low carbon steel and further specifying hot rolling and subsequent cooling conditions as manufacturing conditions. According to the present invention, it is possible to manufacture a cold-rolled steel sheet having good bake hardenability and having deep drawability and in-plane anisotropy that are significantly superior to conventional ones. Can be applied extremely advantageously as a steel sheet for processing automobiles.
【図１】冷間圧延−焼鈍後の鋼板の平均ｒ値におよぼす
仕上げ圧延出側３パスの累積圧下率および熱間圧延後の
冷却速度の影響を示すグラフである。FIG. 1 is a graph showing the influence of the cumulative rolling reduction of the third pass on the finishing rolling exit side and the cooling rate after hot rolling on the average r value of the steel sheet after cold rolling-annealing.
【図２】冷間圧延−焼鈍後の鋼板のΔｒ値におよぼす仕
上げ圧延出側３パスの累積圧下率および熱間圧延後の冷
却速度の影響を示すグラフである。FIG. 2 is a graph showing the influence of the cumulative reduction ratio of the three passes on the finishing rolling exit side and the cooling rate after hot rolling on the Δr value of the steel sheet after cold rolling-annealing.
Claims (1)
％） の関係を満たし、残部は鉄および不可避的不純物の組成
になる鋼スラブを素材として、仕上げ圧延出側３パスで
の累積圧下率を50％以上とする熱間圧延を行い、Ar3 変
態点以上の温度で仕上げ圧延を終了したのち、0.5 秒間
以内に冷却を開始し、Ar3 変態点以上の冷却開始温度か
らAr3 変態点−60℃までの温度域を70〜400 ℃／ｓの範
囲の冷却速度で冷却したのち、 550〜800 ℃の温度範囲
でコイルに巻取り、その後通常の方法で冷間圧延し、連
続焼鈍を施すことを特徴とする成形性に優れる焼付硬化
型冷延鋼板の製造方法。1. C: 0.0010 mass% or less, Si: 0.1 mass% or less, Mn: 0.3 mass% or less, Nb: 0.03 mass% or less, B: 0.0001 to 0.0030 mass% or less, Al: 0.1 mass% or less, P : 0.05 mass% or less, S: 0.005 mass% or less and N: 0.003 mass% or less, and 1 ≦ Nb (mass%) / C (mass%) ≦ 30 and N (mass%)-14/11・ B (mass%) ≤ 0.001 (mass
%) And the balance is iron and inevitable impurities in the steel slab. Hot rolling with cumulative rolling reduction of 50% or more in the 3rd pass of finish rolling is performed, and Ar 3 transformation is performed. After completion of the finish rolling at a point above the temperature to start cooling within 0.5 seconds, the Ar 3 transformation point or more cooling start temperature the temperature range of up to Ar 3 transformation point -60 ° C. of 70 to 400 ° C. / s After being cooled at a cooling rate in the range, it is wound into a coil in the temperature range of 550 to 800 ° C, then cold rolled by the usual method and subjected to continuous annealing, which is a bake hardening type cold rolling with excellent formability. Steel plate manufacturing method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24928794A JP3596045B2 (en) | 1994-10-14 | 1994-10-14 | Manufacturing method of bake hardening type cold rolled steel sheet with excellent formability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24928794A JP3596045B2 (en) | 1994-10-14 | 1994-10-14 | Manufacturing method of bake hardening type cold rolled steel sheet with excellent formability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08109416A true JPH08109416A (en) | 1996-04-30 |
| JP3596045B2 JP3596045B2 (en) | 2004-12-02 |
Family
ID=17190731
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24928794A Expired - Fee Related JP3596045B2 (en) | 1994-10-14 | 1994-10-14 | Manufacturing method of bake hardening type cold rolled steel sheet with excellent formability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3596045B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100467712B1 (en) * | 2000-08-08 | 2005-01-24 | 주식회사 포스코 | The Manufacturing of Bake Hardening Steels with High Formability |
| JP2007009271A (en) * | 2005-06-30 | 2007-01-18 | Jfe Steel Kk | Steel sheet having low anisotropy, and manufacturing method therefor |
-
1994
- 1994-10-14 JP JP24928794A patent/JP3596045B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100467712B1 (en) * | 2000-08-08 | 2005-01-24 | 주식회사 포스코 | The Manufacturing of Bake Hardening Steels with High Formability |
| JP2007009271A (en) * | 2005-06-30 | 2007-01-18 | Jfe Steel Kk | Steel sheet having low anisotropy, and manufacturing method therefor |
| JP4604883B2 (en) * | 2005-06-30 | 2011-01-05 | Ｊｆｅスチール株式会社 | Steel plate with small anisotropy and method for producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3596045B2 (en) | 2004-12-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2011052317A (en) | Dual phase steel sheet and method for manufacturing the same | |
| JP3915460B2 (en) | High strength hot rolled steel sheet and method for producing the same | |
| JP4214671B2 (en) | Ferritic Cr-containing cold-rolled steel sheet excellent in ductility, workability and ridging resistance and method for producing the same | |
| JPH0770650A (en) | Production of cold rolled steel sheet extremely excellent in deep drawability | |
| JP3941363B2 (en) | Ferritic stainless cold-rolled steel sheet excellent in ductility, workability and ridging resistance, and method for producing the same | |
| JPH02163318A (en) | Production of high-tension cold rolled steel sheet having excellent press formability | |
| JP3596045B2 (en) | Manufacturing method of bake hardening type cold rolled steel sheet with excellent formability | |
| JPH06179922A (en) | Production of high tensile strength steel sheet for deep drawing | |
| JP3818025B2 (en) | Method for producing cold-rolled steel sheet with small anisotropy | |
| JP3911075B2 (en) | Manufacturing method of steel sheet for ultra deep drawing with excellent bake hardenability | |
| JP3593728B2 (en) | Manufacturing method of ultra low carbon cold rolled steel sheet with excellent formability | |
| JP3718987B2 (en) | Paint bake-hardening cold-rolled steel sheet excellent in aging resistance and method for producing the same | |
| JPH05171351A (en) | Cold rolled steel sheet for deep drawing having non-aging characteristic and excellent in baking hardenability and its production | |
| JPH0665647A (en) | Effective production of cold rolled steel sheet extremely excellent in deep drawability | |
| JPH0617140A (en) | Production of cold rolled steel sheet for deep drawing | |
| JP3224732B2 (en) | Cold rolled steel sheet having good aging resistance and method for producing the same | |
| JP3261037B2 (en) | Manufacturing method of cold rolled steel sheet with good aging resistance | |
| JP2000199031A (en) | Cold rolled steel sheet excellent in workability and its production | |
| KR100482199B1 (en) | A cold rolled steel sheet with extra deep drawability and its manufacturing method | |
| JPH01177322A (en) | Manufacture of cold rolled steel sheet extremely excellent in deep drawability | |
| JPH01177321A (en) | Manufacture of cold rolled steel sheet excellent in deep drawability | |
| JPH09263879A (en) | Cold rolled steel sheet excellent in workability and aging resistance and its production | |
| JPH09227951A (en) | Manufacture of cold rolled steel sheet for deep drawing | |
| JPH0776410B2 (en) | High-strength cold-rolled steel sheet for non-aging deep drawing excellent in bake hardenability and method for producing the same | |
| JPH06158176A (en) | Production of cold rolled steel sheet excellent in press formability |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20040817 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20040830 |
|
| R150 | Certificate of patent (=grant) or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080917 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080917 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090917 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090917 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100917 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100917 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110917 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110917 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120917 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120917 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130917 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |