JP3544771B2 - Manufacturing method of cold rolled steel sheet with excellent formability - Google Patents
Manufacturing method of cold rolled steel sheet with excellent formability Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、成形性に優れた冷延鋼板の製造方法に関するものである。なお、ここでの冷延鋼板は、表面処理原板として利用することもできるものである。
【０００２】
【従来の技術】
本発明はアルミキルド鋼を対象としているので、その製造工程を中心に、深絞り用鋼板の標準的な製造工程を以下に説明する。
高炉から得られる銑鉄は４％程度のＣを含むが、純酸素を吹込むことにより、転炉精錬段階で、Ｃ含有量は０．０５％程度まで低減される。炭素量をより下げて加工性を向上させる場合は、その後、ＤＨあるいはＲＨなどの真空脱ガス処理で脱炭が行われるが、最近では、そのＣ含有量を１０ｐｐｍ程度まで下げることが可能になってきた。
【０００３】
現在、我が国では、殆どの深絞り用鋼板が連続鋳造により製造されている。連続鋳造で製造されたスラブは、３つのルートで熱間圧延へ供される。１つは、ＣＣ−ＤＲ（Ｃｏｎｔｉｎｕｏｕｓ Ｃａｓｔｉｎｇ ａｎｄ Ｄｉｒｅｃｔ Ｒｏｌｌｉｎｇ）と称され、再加熱することなしに直接熱延される場合で、熱エネルギー的には最も効率的なルートである。この場合、鋳片の温度が大きく下がらないように、設備的な対策が必要なことと、鋳片の手入れができないため、表面品質の劣化を招くおそれがあるなどの欠点もある。深絞り用鋼板は外板に使用されることが多いため、表面品質は特に厳しいので、現在のところＣＣ−ＤＲはほとんど適用されていない。また、２つ目のルートは、スラブを冷塊にし、その後加熱炉で再加熱して熱間圧延に供するルートである。さらに、３つ目のルートは、１つ目のルートと２つ目のルートの中間で、スラブを完全に冷やす前に加熱炉に入れる方式であり、ＨＣＲ（Ｈｏｔ Ｃｈａｒｇｅ）と称されている。スラブ温度がγ→α変態を起こす前に再加熱される場合をＡルート、一度γ／α変態点以下になる場合をＢルートと称している。深絞り用極低炭素鋼は、通常、２つ目あるいは３つ目のＢルートで製造されている。再加熱の温度は１１５０〜１２５０℃が一般に採用されている。
【０００４】
熱間圧延は、一般に、数回の粗圧延を行った後、５〜７スタンドの連続熱間圧延機でＡｒ３ 変態点以上の仕上温度で行い、板厚２〜５ｍｍの熱延板を製造する。巻取温度は、連続焼鈍で高いｒ値を得るためには、７００℃以上の高温にしてセメンタイトを粗大に析出させ、またＡｌＮも析出させる必要がある。しかし、高温巻取は、酸洗性の劣化や材質のバラツキを引き起こしやすいという欠点があるため、一般の連続焼鈍材には、通常、６００℃以下の低温巻取が採用されている。一方、箱焼鈍材は、焼鈍中にＡｌＮを析出させてｒ値に好ましい集合組織を形成するため、巻取時にＡｌＮが析出しないことが重要であり、６００℃以下の低温巻取が必須の条件になっている。
【０００５】
巻取られた熱延コイルは、その後、酸洗され、冷間圧延により０．１５〜２ｍｍ程度の板厚に仕上げられる。冷延コイルは、電解洗浄により表面に付着した油などを取り除いてから、焼鈍に供される。
焼鈍は、通常、生産性の観点から、連続焼鈍によって行われる。しかし、連続焼鈍炉の通板には、幅や厚さの制限があるため、一般に、箱焼鈍も併用されている。
【０００６】
深絞り用鋼板は、表面処理が施されて製品となることが多い。主な表面処理は、溶融亜鉛めっきと各種の電気めっきである。また、自動車のガソリンタンクには、鉛の溶融めっきであるターンめっきが施される。電気めっき用鋼板とターンめっき用鋼板の場合は、上記の焼鈍材を原板として用いるが、溶融亜鉛めっきの鋼板の場合は、冷延鋼板を原板として用い、連続焼鈍と溶融めっきを炉中で行うことができる連続溶融めっきラインで、焼鈍と表面処理を同時に行う。
【０００７】
焼鈍されたコイルは、形状矯正とプレスの際に生じるストレッチャーストレインの発生を防止するために、１％程度の調質圧延に供される。
以上に示したように、通常の製造方法では、アルミキルドの冷延鋼板のｒ値を向上させる方法は、熱延の巻取処理と冷延後の焼鈍方法を駆使することにより図られていた。一方、冷延鋼板のｒ値を高める方法として、熱延板の集合組織を制御することが有効なことが知られている。例えば、ＩＦ鋼をＡｒ３ 変態点以下のフェライト域で熱延することにより、熱延鋼板の集合組織を｛１１１｝が強い集合組織にし、冷延鋼板のｒ値を高める技術が開示されている（特開昭６１−１１９６２１号公報）。
【０００８】
【発明が解決しようとする課題】
しかし、アルミキルド鋼は、通常、フェライト域熱延中に固溶Ｃが存在するため、フェライト域熱延によって｛１１１｝が強い熱延集合組織を得ることができず、一般に、γ域熱延材を用いる場合より、冷延鋼板のｒ値が悪くなる。
本発明は、上記課題を有利に解決して、熱延時に集合組織を制御することにより、冷延鋼板の成形性を向上させることのできる成形性に優れた冷延鋼板の製造方法を提供することを目的とするものである。
【０００９】
【課題を解決するための手段】
すなわち、本発明の要旨とするところは下記のとおりである。
（１）重量比で、Ｃ：０．１％以下、Ｎ：０．０１％以下、Ａｌ：０．００５％以上、１．０％以下を含有する鋼のスラブを熱間圧延する際に、Ａｒ３ 変態点＋１００℃以下、Ａｒ３ 変態点以上の温度で、合計圧下率が５０％以上の熱間仕上圧延を、潤滑を施して摩擦係数が０．２以下の条件で行い、その後、通常の酸洗をした後、５０％以上、９５％以下の圧下率で冷間圧延を行い、再結晶焼鈍を施すことを特徴とする成形性に優れた冷延鋼板の製造方法。
【００１０】
（２）鋼成分として、さらに、重量比で、Ｂ：０．０００２％以上、１１Ｎ／１４＋０．００２％以下を含むことを特徴とする前項（１）記載の成形性に優れた冷延鋼板の製造方法。
（３）熱間粗圧延後、先行材と後行材とを接合して熱間仕上圧延することを特徴とする前項（１）または（２）記載の成形性に優れた冷延鋼板の製造方法。
【００１１】
（４）熱間粗圧延後、先行材と後行材とを接合して熱間仕上圧延するとともに、熱間仕上圧延機と巻取機間の張力を５ＭＰａ以上とすることを特徴とする前項（１）または（２）記載の成形性に優れた冷延鋼板の製造方法。
以下に、本発明を詳細に説明する。
本発明において、Ｃ量を０．１％以下、Ｎ量を０．０１％以下としたのは、これらの値を超える量の添加は、加工性の劣化を招くためである。
【００１２】
Ａｌの含有量の下限を０．００５％としたのは、脱酸を十分に行うためである。また、上限の１．０％は、加工性の観点から限定した。
Ｂは２次加工性の向上に寄与するので、用途によっては、その効果が明瞭に現われる０．０００２％以上の添加が必要である。また、Ｂは固溶ＮをＢＮの形で鋼中から低減し、加工性を向上させる効果がある。その効果は、Ｂ量の増加に伴い増えるが、１１Ｎ／１４でほぼ飽和し、それ以上の添加での効果が小さくなるとともに、１１Ｎ／１４＋０．００２％超の添加は加工性を劣化させるので、上限を１１Ｎ／１４＋０．００２％とした。
【００１３】
他の成分については特に限定はしないが、強度を高め、加工性を著しく悪くしない範囲であるＭｎ≦１．５％、Ｓｉ≦１％、Ｐ≦０．１％の添加は、本発明の趣旨を何ら損なうものではない。
次に、プロセス条件の限定理由について述べる。
本発明者は、冷延鋼板の成形性に及ぼす熱延鋼板の集合組織の影響を詳細に検討したところ、熱延鋼板の表層部に形成される集合組織が冷延鋼板の成形性に悪影響を及ぼすことを見出した。すなわち、熱間圧延ではロールと圧延片の間の摩擦係数が大きいため、板厚中心部では存在しないせん断ひずみが板厚の表面近傍では大きく、それによって結晶回転が板厚中心部と顕著に異なり異質の集合組織が形成される。この集合組織の相違は、その後変態した後も質は変わるものの存在する。
【００１４】
そこで、本発明者はγ域熱延での集合組織制御の研究を精力的に行い、表層部の集合組織形成を中心部のそれに近づけることが、冷延鋼板の成形性を向上させる方策であることを見出した。それを実現する熱間圧延条件が熱間圧延の限定条件になる。その限定条件は、Ａｒ３ 変態点＋１００℃以下、Ａｒ３ 変態点以上の温度で、合計圧下率が５０％以上の熱間仕上圧延を、潤滑を施して摩擦係数が０．２以下の条件で行うことである。
【００１５】
熱間仕上圧延時に潤滑を施してロールと圧延板の間の摩擦係数を０．２以下の条件とするのは、この摩擦係数が０．２超になると表面のせん断ひずみを低減できないためである。
潤滑圧延での全圧下率が小さいと面内異方性を小さくする集合組織の形成が不十分になるため、少なくとも５０％の圧下を、１パスあるいは多パスにより加える必要がある。
【００１６】
その際、熱間仕上圧延温度は、高すぎると、再結晶、粒成長が顕著に起きて集合組織の尖鋭化が阻まれるので、Ａｒ３ 変態点＋１００℃をその上限とした。また、Ａｒ３ 変態点未満で圧延されると、冷延鋼板のｒ値の著しい劣化が見られるので、熱間仕上圧延温度の下限はＡｒ３ 変態点とした。
潤滑圧延では、ロールバイトへの噛み込みの際、噛み込み不良やスリップなどが起る場合が多く、このため１スラブ毎に圧延する場合、ホットストリップの先端が巻取られるまで潤滑を施さないのが一般的な操業である。しかし、この場合、無潤滑部と潤滑部が長手方向で存在し、それらの特性が互いに異なるため、品質管理上支障を来たすことがある。その対策として、粗圧延後、先行の熱延板に該粗圧延材を接合し、連続的に熱間圧延を行えば、無潤滑部をなくすことができるので好ましい。これにより品質の安定性が確保できる。
【００１７】
また、仕上熱間圧延機と巻取機までの張力を５ＭＰａ以上にするとｒ値の向上が見られる。ただし、過剰な張力を加えると板破断を起こすおそれがあるので、上限は５０ＭＰａにすることが好ましい。
冷延率の下限を５０％としたのは、５０％未満の冷延率では優れた成形性が得られないためである。また、冷延率の上限を９５％としたのは、９５％超の冷延率を達成するには冷延機の能力を大きくする必要があり、設備コストが多大になるためである。
【００１８】
再結晶焼鈍については、連続焼鈍でも箱焼鈍でも構わない。また、連続焼鈍の後半で溶融めっきを施すことも本発明の趣旨を損なうものではない。もちろん、焼鈍後、電気めっきなどの表面処理を施すことも本発明の趣旨を損なうものではない。
【００１９】
【発明の実施の形態】
本発明の実施の形態を、実施例により説明する。
実施例には表１に示した成分組成を有する鋼を用いた。鋼種Ａ〜Ｇは本発明鋼、Ｈ、Ｉは比較鋼である。プロセス条件と成品板のｒ値を表２、表３（表２のつづき）に示す。
【００２０】
その他の製造条件については、スラブ加熱温度は１２００℃、スキンパス率は１％とした。
【００２１】
【表１】
【表２】
【表３】
本発明の範囲を満足した実験番号１、２、３、５、６、１０、１１、１３、１７、１９、２１、２３、２５、２７の材料は、γ域熱延時に摩擦係数を０．２以下にしなかった実験番号７、１２、１４、１６、１８、２０、２２、２４、２６の同鋼種の材料に比べてｒ値が０．２前後高い。この結果は、連続焼鈍（ＣＡＬ）、箱焼鈍（ＢＡＦ）の如何にかかわらず確認される。Ａｒ３ 変態点＋１００℃以下、Ａｒ３ 変態点以上の温度での摩擦係数が０．２以下の熱間仕上圧延の全圧下率が４０％と低かった実験番号４の材料のｒ値は、本発明の範囲を満足した実験番号１、２、３の材料に比べて低く、無潤滑圧延材に比べて顕著な向上は見られなかった。熱間仕上圧延温度がＡｒ３ 変態点未満になった実験番号１５の材料のｒ値は、本発明の範囲を満足した材料に比べて低い。冷延率が４０％と小さかった実験番号９の材料のｒ値は、本発明の範囲を満足した材料に比べて低い。
【００２５】
本実施例で実験番号１、５、６、７、１０、１１、１４、１６、１７、１８、１９は、熱延する際に、粗圧延後、先行の粗圧延材に該粗圧延材を接合して、連続的に熱延したものである。その際の仕上圧延機と巻取機間の張力は通常２０ＭＰａ前後であるが、実験番号１１では、故意に張力を３ＭＰａにして圧延した。他の条件はほぼ同じ実験番号１の材料に比べ、実験番号１１の材料は若干ｒ値が低下した。
【００２６】
【発明の効果】
本発明により、熱間圧延時の圧延荷重ならびにトルクを潤滑圧延により低減できるだけでなく、材質面においても冷延鋼板の深絞り性を向上でき、本発明は工業的に価値の高い発明である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a cold-rolled steel sheet having excellent formability. Here, the cold-rolled steel sheet can also be used as a surface-treated original sheet.
[0002]
[Prior art]
Since the present invention is directed to aluminum-killed steel, a standard manufacturing process of a deep-drawing steel plate will be described below, focusing on its manufacturing process.
Pig iron obtained from a blast furnace contains about 4% of C, but by injecting pure oxygen, the C content is reduced to about 0.05% in a converter refining stage. When the workability is improved by further reducing the carbon content, decarburization is performed by vacuum degassing such as DH or RH. Recently, however, the C content can be reduced to about 10 ppm. Have been.
[0003]
At present, most deep drawing steel sheets are manufactured by continuous casting in Japan. Slabs produced by continuous casting are subjected to hot rolling in three routes. One is called CC-DR (Continuous Casting and Direct Rolling), which is the case where hot rolling is performed directly without reheating, and is the most efficient route in terms of thermal energy. In this case, there are disadvantages such as the necessity of equipment measures so that the temperature of the slab does not drop significantly, and the possibility of deterioration of the surface quality because the slab cannot be maintained. Since deep drawing steel sheets are often used for outer panels, the surface quality is particularly severe, and CC-DR is hardly applied at present. The second route is a route in which the slab is made into a cold lump and then reheated in a heating furnace and subjected to hot rolling. Further, the third route is a system in which the slab is placed in a heating furnace before completely cooling the slab between the first route and the second route, and is called an HCR (Hot Charge). The case where the slab temperature is reheated before the γ → α transformation occurs is referred to as route A, and the case where the slab temperature once falls below the γ / α transformation point is referred to as route B. Ultra-low carbon steel for deep drawing is usually manufactured by a second or third B route. As the reheating temperature, 1150 to 1250 ° C. is generally adopted.
[0004]
In general, hot rolling is performed several times of rough rolling, followed by a continuous hot rolling mill of 5 to 7 stands at a finishing temperature of Ar 3 transformation point or higher to produce a hot-rolled sheet having a thickness of 2 to 5 mm. I do. In order to obtain a high r value by continuous annealing, it is necessary to set a high temperature of 700 ° C. or more to coarsely precipitate cementite and also to precipitate AlN. However, high-temperature winding has a drawback of easily causing deterioration in pickling properties and variations in materials. Therefore, low-temperature winding at a temperature of 600 ° C. or lower is usually adopted for general continuous annealing materials. On the other hand, in the case of the box-annealed material, it is important that AlN does not precipitate during winding because AlN is precipitated during annealing to form a texture favorable to the r value, and low-temperature winding at 600 ° C. or lower is an essential condition. It has become.
[0005]
The wound hot-rolled coil is then pickled and cold-rolled to a thickness of about 0.15 to 2 mm. The cold-rolled coil is subjected to annealing after removing oil and the like attached to the surface by electrolytic cleaning.
Annealing is usually performed by continuous annealing from the viewpoint of productivity. However, there is a limitation on the width and the thickness of the continuous annealing furnace, and thus box annealing is generally used together.
[0006]
Deep drawing steel sheets are often subjected to surface treatment to become products. The main surface treatments are hot dip galvanizing and various types of electroplating. In addition, a gasoline tank of an automobile is subjected to turn plating, which is hot-dip plating of lead. In the case of a steel sheet for electroplating and turn plating, the above-mentioned annealed material is used as a base sheet, but in the case of a hot-dip galvanized steel sheet, a cold-rolled steel sheet is used as a base sheet, and continuous annealing and hot-dip are performed in a furnace. Annealing and surface treatment are performed simultaneously in a continuous hot-dip plating line.
[0007]
The annealed coil is subjected to a temper rolling of about 1% in order to prevent the occurrence of stretcher strain generated during shape correction and pressing.
As described above, in the normal manufacturing method, the method of improving the r-value of the aluminum-killed cold-rolled steel sheet has been achieved by making full use of the hot rolling process and the annealing process after the cold rolling. On the other hand, as a method for increasing the r-value of a cold-rolled steel sheet, it is known that controlling the texture of a hot-rolled sheet is effective. For example, a technology has been disclosed in which an IF steel is hot-rolled in a ferrite region below the Ar 3 transformation point to make the texture of the hot-rolled steel sheet have a strong {111} texture, thereby increasing the r-value of the cold-rolled steel sheet. (Japanese Patent Application Laid-Open No. 61-119621).
[0008]
[Problems to be solved by the invention]
However, since aluminum-killed steel usually has solid solution C in hot-rolled in the ferrite region, it is not possible to obtain a hot-rolled texture with {111} strong due to hot-rolling in the ferrite region. The r-value of the cold-rolled steel sheet is worse than when using.
The present invention advantageously solves the above problems, and provides a method for producing a cold-rolled steel sheet having excellent formability capable of improving the formability of a cold-rolled steel sheet by controlling the texture during hot rolling. It is intended for that purpose.
[0009]
[Means for Solving the Problems]
That is, the gist of the present invention is as follows.
(1) When hot rolling a slab of steel containing C: 0.1% or less, N: 0.01% or less, Al: 0.005% or more and 1.0% or less by weight ratio, Hot finish rolling at a temperature not lower than the Ar 3 transformation point + 100 ° C. and not lower than the Ar 3 transformation point and having a total draft of 50% or more is performed under lubricated conditions with a friction coefficient of 0.2 or less. A method for producing a cold-rolled steel sheet having excellent formability, comprising performing cold rolling at a rolling reduction of 50% or more and 95% or less after acid pickling, followed by recrystallization annealing.
[0010]
(2) The cold-rolled steel sheet excellent in formability according to (1), wherein the steel component further contains B: 0.0002% or more and 11N / 14 + 0.002% or less by weight ratio. Production method.
(3) Production of a cold-rolled steel sheet excellent in formability according to the above (1) or (2), wherein, after the rough hot rolling, the preceding material and the following material are joined and hot finish-rolled. Method.
[0011]
(4) The preceding item, wherein after the hot rough rolling, the preceding material and the following material are joined and hot finish-rolled, and the tension between the hot finish rolling mill and the winder is 5 MPa or more. The method for producing a cold-rolled steel sheet excellent in formability according to (1) or (2).
Hereinafter, the present invention will be described in detail.
In the present invention, the reason why the amount of C is set to 0.1% or less and the amount of N is set to 0.01% or less is that addition of an amount exceeding these values causes deterioration of workability.
[0012]
The reason for setting the lower limit of the Al content to 0.005% is to sufficiently perform deoxidation. Further, the upper limit of 1.0% was limited from the viewpoint of workability.
Since B contributes to the improvement of the secondary workability, depending on the use, it is necessary to add 0.0002% or more, at which the effect appears clearly. B has the effect of reducing solid solution N from the steel in the form of BN and improving workability. The effect increases with an increase in the amount of B. However, the effect is almost saturated at 11N / 14, and the effect of further addition decreases, and addition of more than 11N / 14 + 0.002% deteriorates workability. The upper limit was set to 11N / 14 + 0.002%.
[0013]
Other components are not particularly limited, but the addition of Mn ≦ 1.5%, Si ≦ 1%, and P ≦ 0.1%, which are ranges that enhance strength and do not significantly deteriorate workability, are the purpose of the present invention. Does not hurt at all.
Next, the reasons for limiting the process conditions will be described.
The present inventors have studied in detail the influence of the texture of the hot-rolled steel sheet on the formability of the cold-rolled steel sheet, and found that the texture formed in the surface layer portion of the hot-rolled steel sheet adversely affects the formability of the cold-rolled steel sheet. Was found to have an effect. That is, in hot rolling, since the friction coefficient between the roll and the rolled piece is large, the shear strain that does not exist in the center of the sheet thickness is large near the surface of the sheet thickness, so that the crystal rotation is significantly different from the center of the sheet thickness. A heterogeneous texture is formed. This texture difference exists even though the quality changes after the transformation.
[0014]
Therefore, the present inventor has energetically conducted research on texture control in hot rolling in the γ region, and it is a measure to improve the formability of the cold-rolled steel sheet by bringing the texture of the surface layer closer to that of the central part. I found that. The hot rolling conditions for realizing this are the limiting conditions for hot rolling. The limiting conditions are hot finish rolling at a temperature of Ar 3 transformation point + 100 ° C. or lower, a temperature of Ar 3 transformation point or higher, a total draft of 50% or more, lubrication, and a friction coefficient of 0.2 or less. Is to do.
[0015]
The reason why the friction coefficient between the roll and the rolled plate is set to 0.2 or less by performing lubrication during hot finish rolling is that if the friction coefficient exceeds 0.2, the surface shear strain cannot be reduced.
If the total rolling reduction in the lubricating rolling is small, the formation of a texture that reduces in-plane anisotropy becomes insufficient, so it is necessary to apply at least 50% reduction in one pass or multiple passes.
[0016]
At that time, if the hot finish rolling temperature is too high, recrystallization and grain growth occur remarkably, and sharpening of the texture is prevented. Therefore, the upper limit is the Ar 3 transformation point + 100 ° C. Further, when it is rolled by Ar less than 3 transformation point, because significant degradation of the r value of cold-rolled steel sheet is observed, the lower limit of the hot finish rolling temperature was Ar 3 transformation point.
In lubricating rolling, when biting into a roll bite, a biting failure or slip often occurs. Therefore, when rolling one slab at a time, lubrication is not applied until the tip of the hot strip is wound up. Is a common operation. However, in this case, the non-lubricated portion and the lubricated portion exist in the longitudinal direction, and their characteristics are different from each other, which may hinder quality control. As a countermeasure, it is preferable that after rough rolling, the rough rolled material is joined to a preceding hot rolled sheet and hot rolling is continuously performed, because the non-lubricated portion can be eliminated. Thereby, the stability of quality can be secured.
[0017]
Further, when the tension between the finishing hot rolling mill and the winding machine is set to 5 MPa or more, an improvement in the r value is observed. However, the upper limit is preferably set to 50 MPa because excessive tension may cause the plate to break.
The reason why the lower limit of the cold rolling ratio is set to 50% is that excellent moldability cannot be obtained with a cold rolling ratio of less than 50%. The reason why the upper limit of the cold rolling rate is set to 95% is that in order to achieve a cold rolling rate of more than 95%, it is necessary to increase the capacity of the cold rolling machine, and the equipment cost becomes large.
[0018]
Regarding recrystallization annealing, either continuous annealing or box annealing may be used. Further, applying the hot-dip plating in the latter half of the continuous annealing does not impair the purpose of the present invention. Of course, applying a surface treatment such as electroplating after annealing does not impair the gist of the present invention.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described with reference to examples.
In the examples, steels having the component compositions shown in Table 1 were used. Steel types A to G are inventive steels, and H and I are comparative steels. Tables 2 and 3 (continued from Table 2) show the process conditions and the r-value of the product plate.
[0020]
As for other manufacturing conditions, the slab heating temperature was 1200 ° C., and the skin pass ratio was 1%.
[0021]
[Table 1]
[Table 2]
[Table 3]
The materials of Experiment Nos. 1, 2, 3, 5, 6, 10, 11, 13, 17, 19, 21, 23, 25, and 27 satisfying the range of the present invention have a friction coefficient of 0. The r value is about 0.2 higher than that of the same steel type material of Experiment Nos. 7, 12, 14, 16, 18, 20, 22, 24, and 26, which was not set to 2 or less. This result is confirmed regardless of continuous annealing (CAL) or box annealing (BAF). The r-value of the material of Experiment No. 4 in which the total reduction of hot finish rolling with a friction coefficient of 0.2 or less at a temperature not higher than the Ar 3 transformation point + 100 ° C. and higher than the Ar 3 transformation point was as low as 40% was as follows. It was lower than the materials of Experiment Nos. 1, 2 and 3 which satisfied the scope of the invention, and no remarkable improvement was observed as compared with the non-lubricated rolled material. The r value of the material of Experiment No. 15 in which the hot finish rolling temperature was lower than the Ar 3 transformation point was lower than the material satisfying the range of the present invention. The r value of the material of Experiment No. 9 in which the cold rolling reduction was as small as 40% was lower than that of the material satisfying the range of the present invention.
[0025]
In the present embodiment, the experimental numbers 1, 5, 6, 7, 10, 11, 14, 16, 17, 18, and 19 are such that when hot rolling is performed, after rough rolling, the rough rolling material is used as a preceding rough rolling material. It was joined and continuously hot-rolled. The tension between the finishing mill and the winder at that time is usually about 20 MPa, but in Experiment No. 11, the tension was intentionally set to 3 MPa to perform rolling. Under other conditions, the r value of the material of experiment number 11 was slightly lower than that of the material of experiment number 1 which was almost the same.
[0026]
【The invention's effect】
According to the present invention, not only the rolling load and torque during hot rolling can be reduced by lubricating rolling, but also the deep drawability of a cold-rolled steel sheet can be improved in terms of material, and the present invention is an industrially valuable invention.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33211395A JP3544771B2 (en) | 1995-12-20 | 1995-12-20 | Manufacturing method of cold rolled steel sheet with excellent formability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33211395A JP3544771B2 (en) | 1995-12-20 | 1995-12-20 | Manufacturing method of cold rolled steel sheet with excellent formability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09170029A JPH09170029A (en) | 1997-06-30 |
| JP3544771B2 true JP3544771B2 (en) | 2004-07-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33211395A Expired - Fee Related JP3544771B2 (en) | 1995-12-20 | 1995-12-20 | Manufacturing method of cold rolled steel sheet with excellent formability |
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| Country | Link |
|---|---|
| JP (1) | JP3544771B2 (en) |
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1995
- 1995-12-20 JP JP33211395A patent/JP3544771B2/en not_active Expired - Fee Related
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| Publication number | Publication date |
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| JPH09170029A (en) | 1997-06-30 |
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