JP2010275627A - High-strength steel sheet and high-strength hot-dip galvanized steel sheet having excellent workability, and method for producing them - Google Patents

High-strength steel sheet and high-strength hot-dip galvanized steel sheet having excellent workability, and method for producing them Download PDF

Info

Publication number
JP2010275627A
JP2010275627A JP2010038035A JP2010038035A JP2010275627A JP 2010275627 A JP2010275627 A JP 2010275627A JP 2010038035 A JP2010038035 A JP 2010038035A JP 2010038035 A JP2010038035 A JP 2010038035A JP 2010275627 A JP2010275627 A JP 2010275627A
Authority
JP
Japan
Prior art keywords
steel sheet
hot
mass
strength
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
Application number
JP2010038035A
Other languages
Japanese (ja)
Other versions
JP5493986B2 (en
Inventor
Tatsuya Nakagaito
達也 中垣内
Saiji Matsuoka
才二 松岡
Shinjiro Kaneko
真次郎 金子
Yoshiyasu Kawasaki
由康 川崎
Yoshitsugu Suzuki
善継 鈴木
Yasunobu Nagataki
康伸 長滝
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
JFE Steel Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by JFE Steel Corp filed Critical JFE Steel Corp
Priority to JP2010038035A priority Critical patent/JP5493986B2/en
Publication of JP2010275627A publication Critical patent/JP2010275627A/en
Application granted granted Critical
Publication of JP5493986B2 publication Critical patent/JP5493986B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

Landscapes

  • Heat Treatment Of Sheet Steel (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-strength steel sheet and a high-strength hot-dip galvanized steel sheet having excellent ductility, stretch flange formability and bendability. <P>SOLUTION: The steel sheet has a componential composition comprising, by mass, 0.05 to 0.3% C, 0.01 to 2.5% Si, 0.5 to 3.5% Mn, 0.003 to 0.100% P, ≤0.02% S and 0.010 to 1.5% Al, and in which the total of the contents of Si and Al is 0.5 to 3.0%, and the balance iron with inevitable impurities, and has a metallic structure comprising, by area ratio, ferrite of ≥20%, tempered martensite of 10 to 60% and martensite of 0 to 10%, and comprising, by volume ratio, retained austenite of 3 to 10%, and in which the ratio (m) between the Vickers hardness (m) of the tempered martensite and the Vickers hardness (f) of the ferrite, (m)/(f) is ≤3.0. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、自動車、電気機器等の産業分野で使用される部材に好適な成形加工性に優れた高強度鋼板および高強度溶融亜鉛めっき鋼板並びにそれらの製造方法に関するものである。   The present invention relates to a high-strength steel sheet and a high-strength hot-dip galvanized steel sheet excellent in forming processability suitable for members used in industrial fields such as automobiles and electrical equipment, and methods for producing them.

近年、地球環境の保全の見地から、自動車の燃費向上が重要な課題となっている。このため、車体材料の高強度化により薄肉化を図り、車体そのものを軽量化しようとする動きが活発化しつつある。しかしながら、鋼板の高強度化は延性の低下、即ち成形加工性の低下を招くことから、高強度と高加工性を併せ持つ材料の開発が望まれている。
さらには、最近の自動車用材料についての耐食性向上の要求の高まりもあって、溶融亜鉛めっきを施した高張力鋼板の開発も盛んに行われている。
In recent years, improving the fuel efficiency of automobiles has become an important issue from the viewpoint of conservation of the global environment. For this reason, a movement to reduce the thickness of the vehicle body by increasing the strength of the vehicle body material and to reduce the weight of the vehicle body is becoming active. However, increasing the strength of the steel sheet causes a decrease in ductility, that is, a decrease in forming processability, and therefore development of a material having both high strength and high processability is desired.
Furthermore, due to the recent increasing demand for improved corrosion resistance for automotive materials, development of hot-dip galvanized high-tensile steel sheets has been actively conducted.

以上のような要求に対して、これまでにフェライト、マルテンサイト二相鋼(DP鋼)や残留オーステナイトの変態誘起塑性を利用したTRIP鋼など、種々の複合組織型高強度鋼板や複合組織型高強度溶融亜鉛めっき鋼板が開発されてきた。
複合組織型高強度溶融亜鉛めっき鋼板に関しては、例えば、特許文献1では多量のSiを添加することにより残留オーステナイトを確保し、高延性を達成する加工性に優れた合金化溶融亜鉛めっき鋼板が提案されている。
しかし、これらDP鋼やTRIP鋼は、伸び特性には優れるものの穴拡げ性が劣るという問題がある。この穴拡げ性は、加工穴部を拡張してフランジ成形する際の加工性を示す指標であり、伸び特性とともに高強度鋼板に要求される重要な特性である。
In response to the above requirements, various high-strength steel sheets and high-strength steel structures such as ferrite, martensite duplex steel (DP steel), and TRIP steel using transformation-induced plasticity of retained austenite have been developed. Strength hot dip galvanized steel sheets have been developed.
For example, Patent Document 1 proposes an alloyed hot-dip galvanized steel sheet with excellent workability that secures retained austenite by adding a large amount of Si and achieves high ductility. Has been.
However, although these DP steels and TRIP steels are excellent in elongation characteristics, there is a problem that the hole expandability is inferior. This hole expansibility is an index indicating workability at the time of flange forming by expanding a processed hole, and is an important characteristic required for a high-strength steel sheet together with elongation characteristics.

伸びフランジ性(穴拡げ性)に優れる溶融亜鉛めっき鋼板の製造方法として、特許文献2には、焼鈍均熱後、溶融亜鉛めっき浴までの間にMs点以下まで強冷却して生成したマルテンサイトを再加熱し、焼戻しマルテンサイトとすることで穴拡げ性を向上させる技術が開示されている。しかし、この技術では、マルテンサイトを焼戻しマルテンサイトにすることにより穴拡げ性は向上するが、ELが低いことが問題となる。
さらに、引張強度が900MPaを超えるような強度では、プレス成形時に曲げ成形による割れが問題になるケースが増加し、上記延性および伸びフランジ性と併せて、曲げ性も必要となる。
As a method for producing a hot-dip galvanized steel sheet having excellent stretch flangeability (hole expandability), Patent Document 2 describes martensite produced by intense cooling to the Ms point or less after annealing and soaking until the hot-dip galvanizing bath. A technique for improving the hole expansibility by re-heating the tempered martensite is disclosed. However, with this technique, the hole expandability is improved by changing the martensite to tempered martensite, but the problem is that the EL is low.
Furthermore, when the tensile strength exceeds 900 MPa, the number of cases in which cracking due to bending is problematic during press molding increases, and in addition to the ductility and stretch flangeability, bendability is also required.

特開平11−279691号公報Japanese Patent Application Laid-Open No. 11-296991 特開平6−93340号公報Japanese Patent Laid-Open No. 6-93340

以上のように、高強度鋼板や高強度溶融亜鉛めっき鋼板には優れた延性、伸びフランジ性および曲げ性が要求されるが、従来の鋼板や溶融亜鉛めっき鋼板には、これらを全て高いレベルで兼ね備えるものは無かった。
したがって本発明の目的は、延性、伸びフランジ性および曲げ性に優れる高強度鋼板および高強度溶融亜鉛めっき鋼板とそれらの製造方法を提供することにある。
As described above, high-strength steel sheets and high-strength hot-dip galvanized steel sheets are required to have excellent ductility, stretch flangeability, and bendability, but conventional steel sheets and hot-dip galvanized steel sheets are all at a high level. There was nothing to combine.
Accordingly, an object of the present invention is to provide a high-strength steel sheet and a high-strength hot-dip galvanized steel sheet that are excellent in ductility, stretch flangeability, and bendability, and methods for producing them.

本発明者らは、上記した課題を解決し、延性、伸びフランジ性および曲げ性に優れた高強度鋼板と高強度溶融亜鉛めっき鋼板を得るために、鋼板の成分組成およびミクロ組織の観点から鋭意研究を重ねた。その結果、合金元素の含有量と熱間圧延条件を最適化して、熱延鋼板をベイナイトとマルテンサイトを主体とした組織とし、この熱延鋼板または熱延鋼板を冷間圧延して得られた冷延鋼板を特定の条件で連続焼鈍する(溶融亜鉛めっき鋼板の場合には、その後に溶融亜鉛めっきを施し、さらに必要に応じてめっき合金化処理を施す)ことで、面積率でフェライトを20%以上、焼戻しマルテンサイトを10〜60%含み、体積率で残留オーステナイトを3〜10%含み、焼戻しマルテンサイトとフェライトのビッカース硬度比が3.0以下、好ましくは2.0〜3.0である金属組織とすることにより、高い延性、伸びフランジ性および曲げ性を兼ね備えた高強度鋼板や高強度溶融亜鉛めっき鋼板が得られることが判った。一般に、残留オーステナイトが存在すると残留オーステナイトのTRIP効果により延性が向上する。しかし、歪の付加により残留オーステナイトが変態して生成するマルテンサイトは非常に硬質なものとなり、その結果、主相であるフェライトとの硬度差が大きくなり伸びフランジ性や曲げ性が低下することが知られている。本発明では、フェライトと残留オーステナイトとともに焼戻しマルテンサイトを共存させることにより、上記のような伸びフランジ性や曲げ性の低下を抑制し、高い延性、伸びフランジ性および曲げ性が得られる。さらに、焼戻しマルテンサイトとフェライトの硬度比が曲げ特性に大きく影響し、高い曲げ性を達成するためには、その硬度比を3.0以下の範囲に制御することが重要であることが判った。   In order to solve the above-described problems and obtain a high-strength steel sheet and a high-strength hot-dip galvanized steel sheet excellent in ductility, stretch flangeability, and bendability, the present inventors have earnestly studied from the viewpoint of the component composition and microstructure of the steel sheet. Repeated research. As a result, it was obtained by optimizing the content of the alloy elements and the hot rolling conditions, making the hot rolled steel sheet mainly composed of bainite and martensite, and cold rolling the hot rolled steel sheet or hot rolled steel sheet. By continuously annealing a cold-rolled steel sheet under specific conditions (in the case of a hot-dip galvanized steel sheet, hot-dip galvanizing is performed thereafter, and if necessary, a plating alloying treatment is performed), so that ferrite is 20 in area ratio. % Or more, containing 10-60% tempered martensite, containing 3-10% retained austenite by volume, and having a Vickers hardness ratio of tempered martensite and ferrite of 3.0 or less, preferably 2.0-3.0 It was found that a high-strength steel sheet and a high-strength hot-dip galvanized steel sheet having high ductility, stretch flangeability and bendability can be obtained by using a certain metal structure. In general, when retained austenite is present, ductility is improved by the TRIP effect of retained austenite. However, the martensite produced by transformation of retained austenite due to the addition of strain becomes very hard, and as a result, the hardness difference from the main phase ferrite increases and stretch flangeability and bendability may decrease. Are known. In the present invention, the coexistence of tempered martensite together with ferrite and retained austenite suppresses the deterioration of stretch flangeability and bendability as described above, and high ductility, stretch flangeability and bendability are obtained. Furthermore, it was found that the hardness ratio of tempered martensite and ferrite has a great influence on the bending characteristics, and in order to achieve high bendability, it is important to control the hardness ratio within a range of 3.0 or less. .

本発明はこのような知見に基づきなされたもので、以下を要旨とするものである。
[1]C:0.05〜0.3質量%、Si:0.01〜2.5質量%、Mn:0.5〜3.5質量%、P:0.003〜0.100質量%、S:0.02質量%以下、Al:0.010〜1.5質量%を含有し、SiとAlの含有量の合計が0.5〜3.0質量%であり、残部が鉄および不可避的不純物からなる成分組成を有し、面積率でフェライトを20%以上、焼戻しマルテンサイトを10〜60%、マルテンサイトを0〜10%を含み、体積率で残留オーステナイトを3〜10%含み、焼戻しマルテンサイトのビッカース硬度(m)とフェライトのビッカース硬度(f)の比(m)/(f)が3.0以下である金属組織を有することを特徴とする加工性に優れた高強度鋼板。
The present invention has been made on the basis of such findings and has the following gist.
[1] C: 0.05 to 0.3% by mass, Si: 0.01 to 2.5% by mass, Mn: 0.5 to 3.5% by mass, P: 0.003 to 0.100% by mass , S: 0.02% by mass or less, Al: 0.010 to 1.5% by mass, the total content of Si and Al is 0.5 to 3.0% by mass, the balance being iron and It has a component composition consisting of inevitable impurities, including 20% or more of ferrite by area ratio, 10 to 60% of tempered martensite, 0 to 10% of martensite, and 3 to 10% of retained austenite by volume ratio. High strength with excellent workability characterized by having a metal structure in which the ratio (m) / (f) of Vickers hardness (m) of tempered martensite to Vickers hardness (f) of ferrite is 3.0 or less steel sheet.

[2]上記[1]の高強度鋼板において、さらに、Cr:0.005〜2.00質量%、Mo:0.005〜2.00質量%、V:0.005〜2.00質量%、Ni:0.005〜2.00質量%、Cu:0.005〜2.00質量%のなかから選ばれる1種または2種以上を含有することを特徴とする加工性に優れた高強度鋼板。
[3]上記[1]または[2]の高強度鋼板において、さらに、Ti:0.01〜0.20質量%、Nb:0.01〜0.20質量%のなかから選ばれる1種または2種を含有することを特徴とする加工性に優れた高強度鋼板。
[4]上記[1]〜[3]のいずれかの高強度鋼板において、さらに、B:0.0002〜0.005質量%を含有することを特徴とする加工性に優れた高強度鋼板。
[5]上記[1]〜[4]のいずれかの高強度鋼板において、さらに、Ca:0.0001〜0.005質量%、REM:0.0001〜0.005質量%のなかから選ばれる1種または2種を含有することを特徴とする加工性に優れた高強度鋼板。
[2] In the high-strength steel sheet of [1], Cr: 0.005 to 2.00% by mass, Mo: 0.005 to 2.00% by mass, V: 0.005 to 2.00% by mass Ni: 0.005 to 2.00% by mass, Cu: 0.005 to 2.00% by mass, containing one or more selected from high strength and excellent strength steel sheet.
[3] In the high-strength steel sheet of [1] or [2], one or more selected from Ti: 0.01-0.20% by mass and Nb: 0.01-0.20% by mass or A high-strength steel sheet excellent in workability characterized by containing two types.
[4] A high-strength steel plate excellent in workability, characterized in that the high-strength steel plate according to any one of [1] to [3] above further contains B: 0.0002 to 0.005 mass%.
[5] In the high-strength steel sheet according to any one of [1] to [4] above, it is further selected from Ca: 0.0001 to 0.005 mass% and REM: 0.0001 to 0.005 mass%. A high-strength steel sheet excellent in workability characterized by containing one or two kinds.

[6]上記[1]〜[5]のいずれかの高強度鋼板において、焼戻しマルテンサイトのビッカース硬度(m)とフェライトのビッカース硬度(f)の比(m)/(f)が2.0〜3.0であることを特徴とする加工性に優れた高強度鋼板。
[7]下地鋼板が上記[1]〜[6]のいずれかに記載の鋼板からなることを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板。
[8]上記[1]〜[5]のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持した後、室温まで冷却することを特徴とする加工性に優れた高強度鋼板の製造方法。
[6] In the high-strength steel sheet according to any one of [1] to [5] above, the ratio (m) / (f) of Vickers hardness (m) of tempered martensite to Vickers hardness (f) of ferrite is 2.0. A high-strength steel sheet excellent in workability, characterized by being -3.0.
[7] A high-strength hot-dip galvanized steel sheet excellent in workability, characterized in that the base steel sheet is made of the steel sheet according to any one of [1] to [6].
[8] Hot-rolling a steel slab having the component composition according to any one of [1] to [5] above and having a metal structure in which the total area ratio of bainite and martensite is 80% or more When performing continuous annealing on this hot-rolled steel sheet, after heating to 750-900 ° C and holding for 10 seconds or more, from 750 ° C to a temperature range of 100-350 ° C with an average cooling rate of 10 ° C / second or more A method for producing a high-strength steel sheet excellent in workability, characterized by cooling and then reheating to 350 to 600 ° C. and holding for 10 to 600 seconds, followed by cooling to room temperature.

[9]上記[1]〜[5]のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板を冷間圧延して冷延鋼板とし、この冷延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持した後、室温まで冷却することを特徴とする加工性に優れた高強度鋼板の製造方法。
[10]上記[8]または[9]の製造方法において、熱間圧延工程では、Ar変態点以上の仕上圧延温度で圧延を終了した後、50℃/秒以上の平均冷却速度で冷却し、300〜550℃で巻取ることを特徴とする加工性に優れた高強度鋼板の製造方法。
[9] Hot-rolling a steel slab having the component composition according to any one of [1] to [5] above and having a metal structure in which the total area ratio of bainite and martensite is 80% or more In this case, the hot-rolled steel sheet was cold-rolled to obtain a cold-rolled steel sheet. When the cold-rolled steel sheet was subjected to continuous annealing, the steel sheet was heated to 750-900 ° C and held for 10 seconds or more, and then from 750 ° C to 10 ° C / Cooled to a temperature range of 100 to 350 ° C. at an average cooling rate of at least 2 seconds, then reheated to 350 to 600 ° C., held for 10 to 600 seconds, and then cooled to room temperature, excellent in workability Manufacturing method of high strength steel sheet.
[10] In the manufacturing method of [8] or [9] above, in the hot rolling step, after the rolling is finished at a finish rolling temperature not lower than the Ar 3 transformation point, cooling is performed at an average cooling rate of 50 ° C./second or higher. The manufacturing method of the high strength steel plate excellent in workability characterized by winding at 300-550 degreeC.

[11]上記[1]〜[5]のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持し、しかる後、溶融亜鉛めっきを施すことを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。
[12]上記[1]〜[5]のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板を冷間圧延して冷延鋼板とし、この冷延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持し、しかる後、溶融亜鉛めっきを施すことを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。
[11] Hot-rolling a steel slab having the component composition according to any one of [1] to [5] above and having a metal structure in which the total area ratio of bainite and martensite is 80% or more When performing continuous annealing on this hot-rolled steel sheet, after heating to 750-900 ° C and holding for 10 seconds or more, from 750 ° C to a temperature range of 100-350 ° C with an average cooling rate of 10 ° C / second or more A method for producing a high-strength hot-dip galvanized steel sheet excellent in workability, characterized in that it is cooled, then reheated to 350-600 ° C. and held for 10-600 seconds, and then hot-dip galvanized.
[12] Hot-rolling a steel slab having the composition according to any one of [1] to [5] above and having a metal structure in which the total area ratio of bainite and martensite is 80% or more In this case, the hot-rolled steel sheet was cold-rolled to obtain a cold-rolled steel sheet. When the cold-rolled steel sheet was subjected to continuous annealing, the steel sheet was heated to 750 to 900 ° C. and held for 10 seconds or more, and then from 750 ° C. to 10 ° C. / Workability characterized in that it is cooled to a temperature range of 100 to 350 ° C. at an average cooling rate of at least 2 seconds, then reheated to 350 to 600 ° C. and held for 10 to 600 seconds, and then hot dip galvanized. For producing high-strength hot-dip galvanized steel sheets with excellent resistance.

[13]上記[11]または[12]の製造方法において、熱間圧延工程では、Ar変態点以上の仕上圧延温度で圧延を終了した後、50℃/秒以上の平均冷却速度で冷却し、300〜550℃で巻取ることを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。
[14]上記[11]〜[13]のいずれかの製造方法において、溶融亜鉛めっきを施した後、めっき合金化処理を行うことを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。
[13] In the production method of [11] or [12] above, in the hot rolling step, after the rolling is finished at a finish rolling temperature not lower than the Ar 3 transformation point, cooling is performed at an average cooling rate of 50 ° C./second or higher. The manufacturing method of the high intensity | strength hot-dip galvanized steel plate excellent in workability characterized by winding at 300-550 degreeC.
[14] In the manufacturing method according to any one of [11] to [13] above, a high-strength hot-dip galvanized steel sheet excellent in workability characterized by performing a plating alloying treatment after hot-dip galvanizing Production method.

本発明の鋼板および溶融亜鉛めっき鋼板は、高強度で且つ優れた成形加工性(延性、伸びフランジ性、曲げ性)を有する。このため、特に自動車用材料として、自動車の軽量化と衝突安全性向上を両立させ、自動車車体の高性能化に大きく寄与する。
また、本発明の製造方法によれば、上記のような優れた性能を有する鋼板および溶融亜鉛めっき鋼板を安定して製造することができる。
The steel sheet and hot-dip galvanized steel sheet of the present invention have high strength and excellent formability (ductility, stretch flangeability, bendability). For this reason, particularly as a material for automobiles, it is possible to achieve both weight reduction of automobiles and improvement of collision safety, and greatly contribute to improvement in performance of automobile bodies.
Moreover, according to the manufacturing method of this invention, the steel plate and hot-dip galvanized steel plate which have the above outstanding performances can be manufactured stably.

まず、本発明の鋼板およびこの鋼板の表面に溶融亜鉛めっき皮膜を有する溶融亜鉛めっき鋼板について、鋼の成分組成の限定理由について説明する。
・C:0.05〜0.3質量%
Cはオーステナイトを安定化させる元素であり、フェライト以外の相を生成しやすくするため、鋼板強度を上昇させるとともに、組織を複合化してTS−ELバランスを向上させるために必要な元素である。C量が0.05質量%未満では、製造条件の最適化を図ったとしてもフェライト以外の相の確保が難しく、TS×ELが低下する。一方、C量が0.3質量%を超えると、溶接部および熱影響部の硬化が著しく、溶接部の機械的特性が劣化する。このような観点から、C量は0.05〜0.3質量%、好ましくは0.08〜0.15質量%とする。
First, the reason for limitation of the component composition of steel is demonstrated about the steel plate of this invention and the hot dip galvanized steel plate which has a hot dip galvanized film on the surface of this steel plate.
C: 0.05 to 0.3% by mass
C is an element that stabilizes austenite, and is an element necessary for increasing the steel sheet strength and improving the TS-EL balance by increasing the steel sheet strength in order to easily generate phases other than ferrite. If the C content is less than 0.05% by mass, it is difficult to secure a phase other than ferrite even if the production conditions are optimized, and TS × EL decreases. On the other hand, when the amount of C exceeds 0.3% by mass, the welded portion and the heat affected zone are significantly hardened, and the mechanical properties of the welded portion are deteriorated. From such a viewpoint, the C content is 0.05 to 0.3% by mass, preferably 0.08 to 0.15% by mass.

・Si:0.01〜2.5質量%
Siは鋼の強化に有効な元素である。また、フェライト生成元素であり、オーステナイト中のCの濃化促進および炭化物の生成を抑制することから、残留オーステナイトの生成を促進する働きを有する。Si量が0.01質量%未満ではそのような効果が十分に得られない。一方、Siを過剰に添加すると、延性や表面性状、溶接性が劣化する。このような観点から、Si量は0.01〜2.5質量%、好ましくは0.7〜2.0質量%とする。
・Mn:0.5〜3.5質量%
Mnは鋼の強化に有効な元素であり、焼戻しマルテンサイト等の低温変態相の生成を促進する。このような効果は、Mn量が0.5質量%以上で認められる。一方、Mnを3.5質量%を超えて過剰に添加すると、第二相分率の過剰な増加や固溶強化によるフェライトの延性劣化が著しくなり、成形性が低下する。このような観点から、Mn量は0.5〜3.5質量%、好ましくは1.5〜3.0質量%とする。
-Si: 0.01-2.5 mass%
Si is an element effective for strengthening steel. Further, it is a ferrite-forming element and has the function of promoting the formation of retained austenite because it promotes the concentration of C in austenite and suppresses the formation of carbides. If the amount of Si is less than 0.01% by mass, such an effect cannot be sufficiently obtained. On the other hand, when Si is added excessively, ductility, surface properties, and weldability deteriorate. From such a viewpoint, the Si amount is 0.01 to 2.5% by mass, preferably 0.7 to 2.0% by mass.
Mn: 0.5 to 3.5% by mass
Mn is an element effective for strengthening steel and promotes the generation of low-temperature transformation phases such as tempered martensite. Such an effect is recognized when the amount of Mn is 0.5 mass% or more. On the other hand, when Mn is added excessively exceeding 3.5 mass%, the ductile deterioration of ferrite due to excessive increase of the second phase fraction or solid solution strengthening becomes remarkable, and the formability is lowered. From such a viewpoint, the amount of Mn is 0.5 to 3.5% by mass, preferably 1.5 to 3.0% by mass.

・P:0.003〜0.100質量%
Pは鋼の強化に有効な元素であり、この効果は0.003質量%以上で得られる。しかし、Pを0.100質量%を超えて過剰に添加すると粒界偏析により脆化を引き起こし、耐衝撃性を劣化させる。このような観点からP量は0.003〜0.100質量%とする。
・S:0.02質量%以下
SはMnSなどの介在物となって、耐衝撃特性の劣化や溶接部のメタルフローに沿った割れの原因になるので極力低い方が良いが、製造コストの面から0.02質量%以下とする。
・ P: 0.003 to 0.100 mass%
P is an element effective for strengthening steel, and this effect is obtained at 0.003% by mass or more. However, when P is added excessively exceeding 0.100 mass%, embrittlement is caused by grain boundary segregation and impact resistance is deteriorated. From such a viewpoint, the P amount is set to 0.003 to 0.100 mass%.
・ S: 0.02% by mass or less S is an inclusion such as MnS, which may cause deterioration of impact resistance and cracking along the metal flow of the weld. 0.02 mass% or less from the surface.

・Al:0.010〜1.5質量%、Si+Al:0.5〜3.0質量%
Alは脱酸剤として作用し、鋼の清浄度に有効な元素であり、脱酸工程で添加することが好ましい。Al量が0.010質量%未満ではそのような効果が十分に得られないので、下限を0.010質量%とする。また、AlはSiと同様にフェライト生成元素であり、オーステナイト中へのCの濃化促進および炭化物の生成を抑制することから、残留オーステナイトの生成を促進する働きがある。このような効果はAlとSiの添加量の合計が0.5質量%未満では不十分であり、十分な延性が得られない。しかし、多量に添加すると連続鋳造時の鋼片割れ発生の危険性が高まり製造性を低下させる。このためAl量の上限は1.5質量%、Si量+Al量の上限は3.0質量%とする。
・ Al: 0.010 to 1.5 mass%, Si + Al: 0.5 to 3.0 mass%
Al acts as a deoxidizer and is an element effective for the cleanliness of steel, and is preferably added in the deoxidation step. If the Al content is less than 0.010% by mass, such an effect cannot be obtained sufficiently, so the lower limit is made 0.010% by mass. Al, like Si, is a ferrite-forming element and has the function of promoting the formation of retained austenite because it promotes the concentration of C in austenite and suppresses the formation of carbides. Such an effect is insufficient when the total amount of Al and Si added is less than 0.5% by mass, and sufficient ductility cannot be obtained. However, if it is added in a large amount, the risk of steel piece cracking during continuous casting increases and the productivity decreases. For this reason, the upper limit of Al amount is 1.5% by mass, and the upper limit of Si amount + Al amount is 3.0% by mass.

本発明の高強度鋼板および高強度溶融亜鉛めっき鋼板は、上記の成分組成を基本成分とし、残部は鉄および不可避的不純物からなるが、所望の特性に応じて、以下に述べる成分を適宜含有させることができる。
・Cr:0.005〜2.00質量%、Mo:0.005〜2.00質量%、V:0.005〜2.00質量%、Ni:0.005〜2.00質量%、Cu:0.005〜2.00質量%のなかから選ばれる1種または2種以上
Cr、Mo、V、Ni、Cuは焼鈍温度からの冷却時にパーライトの生成を抑制し、低温変態相の生成を促進し、鋼の強化に有効に作用する。このような効果は、Cr、Mo、V、Ni、Cuの各含有量が0.005質量%以上で得られる。しかし、Cr、Mo、V、Ni、Cuの各含有量が2.00質量%を超えるとその効果は飽和し、コストアップの要因となる。このためCr、Mo、V、Ni、Cuの含有量は、それぞれ0.005〜2.00質量%とする。
The high-strength steel sheet and high-strength hot-dip galvanized steel sheet according to the present invention have the above-described component composition as a basic component, and the balance is composed of iron and unavoidable impurities, but appropriately contain the components described below according to desired characteristics. be able to.
Cr: 0.005-2.00 mass%, Mo: 0.005-2.00 mass%, V: 0.005-2.00 mass%, Ni: 0.005-2.00 mass%, Cu : One or more selected from 0.005 to 2.00% by mass Cr, Mo, V, Ni, Cu suppresses the formation of pearlite during cooling from the annealing temperature, and generates a low-temperature transformation phase. Promotes and works effectively in strengthening steel. Such an effect is obtained when each content of Cr, Mo, V, Ni, and Cu is 0.005 mass% or more. However, when each content of Cr, Mo, V, Ni, and Cu exceeds 2.00% by mass, the effect is saturated, resulting in a cost increase. For this reason, content of Cr, Mo, V, Ni, and Cu shall be 0.005-2.00 mass%, respectively.

・Ti:0.01〜0.20質量%、Nb:0.01〜0.20質量%のなかから選ばれる1種または2種
Ti、Nbは炭窒化物を形成し、鋼を析出強化により高強度化する作用を有する。このような効果は、Ti、Nbの各含有量が0.01質量%以上で認められる。一方、Ti、Nbがそれぞれ0.20質量%を超えて含有すると、過度に高強度化し、延性が低下する。このため、Ti、Nbの含有量は、それぞれ0.01〜0.20質量%とする。
-Ti: 0.01-0.20% by mass, Nb: 1 or 2 types selected from 0.01-0.20% by mass Ti, Nb forms carbonitrides and precipitates steel by precipitation strengthening Has the effect of increasing strength. Such an effect is recognized when each content of Ti and Nb is 0.01% by mass or more. On the other hand, when Ti and Nb each contain more than 0.20 mass%, it will become excessively strong and ductility will fall. For this reason, content of Ti and Nb shall be 0.01-0.20 mass%, respectively.

・B:0.0002〜0.005質量%
Bはオーステナイト粒界からのフェライトの生成を抑制し、強度を上昇させる作用を有する。このような効果は、B量が0.0002質量%以上で得られる。しかし、B量が0.005質量%を超えるとその効果は飽和し、コストアップの要因となる。このためB量は0.0002〜0.005質量%とする。
・Ca:0.0001〜0.005質量%、REM:0.0001〜0.005質量%のなかから選ばれる1種または2種
Ca、REMは、いずれも硫化物の形態制御により加工性を改善する効果を有しており、このような効果はCa、REMの各含有量が0.0001質量%以上で得られる。しかし、過剰な添加は清浄度に悪影響を及ぼす恐れがある。このためCa、REMの含有量は、それぞれ0.0001〜0.005質量%とする。
B: 0.0002 to 0.005 mass%
B has the effect of suppressing the formation of ferrite from the austenite grain boundaries and increasing the strength. Such an effect is obtained when the B content is 0.0002 mass% or more. However, if the amount of B exceeds 0.005% by mass, the effect is saturated and causes an increase in cost. For this reason, the amount of B shall be 0.0002-0.005 mass%.
-Ca: 0.0001 to 0.005 mass%, REM: One or two types selected from 0.0001 to 0.005 mass% Ca and REM are both workable by controlling the form of sulfide. It has the effect of improving, and such an effect is obtained when the content of Ca and REM is 0.0001% by mass or more. However, excessive addition can adversely affect cleanliness. For this reason, content of Ca and REM shall be 0.0001-0.005 mass%, respectively.

次に、本発明の高強度鋼板および高強度溶融亜鉛めっき鋼板の金属組織の限定理由について説明する。
・フェライトの面積率:20%以上
フェライトの面積率が20%未満では、TSとELのバランスが低下する。このためフェライトの面積率は20%以上とする。
・焼戻しマルテンサイトの面積率:10〜60%
焼戻しマルテンサイトとは、マルテンサイトをAc変態点以下の温度に加熱して得られる転位密度の高いフェライトとセメンタイトとの複合組織であり、鋼の強化に有効に働く。また、焼戻しマルテンサイトは、残留オーステナイトやマルテンサイトに比べて穴拡げ性への悪影響が小さく、顕著な穴拡げ性の低下なしに強度を確保するのに有効な金属相である。さらに、焼戻しマルテンサイトが残留オーステナイトやマルテンサイトと共存することにより、残留オーステナイトやマルテンサイトによる伸びフランジ性の低下も抑制される。焼戻しマルテンサイトの面積率が10%未満ではそのような効果が十分に得られず、一方、60%を超えるとTSとELのバランスが低下する。このため焼戻しマルテンサイトの面積率は10〜60%とする。
Next, the reasons for limiting the metal structures of the high-strength steel sheet and high-strength hot-dip galvanized steel sheet according to the present invention will be described.
-Ferrite area ratio: 20% or more If the ferrite area ratio is less than 20%, the balance between TS and EL decreases. Therefore, the area ratio of ferrite is set to 20% or more.
-Area ratio of tempered martensite: 10-60%
Tempered martensite is a composite structure of ferrite and cementite having a high dislocation density obtained by heating martensite to a temperature equal to or lower than the Ac 1 transformation point, and effectively works to strengthen steel. Tempered martensite is a metal phase that has less adverse effects on hole expandability than retained austenite and martensite and is effective in ensuring strength without a significant decrease in hole expandability. Furthermore, when tempered martensite coexists with retained austenite and martensite, a decrease in stretch flangeability due to retained austenite and martensite is also suppressed. If the area ratio of tempered martensite is less than 10%, such an effect cannot be sufficiently obtained, while if it exceeds 60%, the balance between TS and EL is lowered. Therefore, the area ratio of tempered martensite is 10 to 60%.

・マルテンサイトの面積率:0〜10%
マルテンサイト相は鋼の高強度化には有効に働くが、面積率が10%を超えて過剰に存在すると伸びフランジ性が顕著に低下する。このためマルテンサイトの面積率は10%以下とする。マルテンサイトを全く含まず、その面積率が0%でも本発明の効果には影響を及ぼさず問題はない。
・残留オーステナイトの体積率:3〜10%
残留オーステナイトは鋼の強化に寄与するだけでなく、鋼のTSとELのバランスの向上に有効に働く。このような効果は体積率が3%以上で得られる。一方、残留オーステナイト相は加工によりマルテンサイトに変態し、伸びフランジ性が低下する。残留オーステナイトの体積率が10%を超えると伸びフランジ性および曲げ性が顕著に低下する。このため残留オーステナイトの体積率は3〜10%とする。
-Martensite area ratio: 0-10%
The martensite phase works effectively to increase the strength of the steel, but if the area ratio exceeds 10% and exists excessively, the stretch flangeability is significantly lowered. For this reason, the area ratio of martensite is 10% or less. Even if the martensite is not included at all and the area ratio is 0%, the effect of the present invention is not affected and there is no problem.
-Volume ratio of retained austenite: 3 to 10%
Residual austenite not only contributes to the strengthening of the steel, but also works effectively to improve the balance between steel TS and EL. Such an effect is obtained when the volume ratio is 3% or more. On the other hand, the retained austenite phase is transformed into martensite by processing, and stretch flangeability is lowered. When the volume fraction of retained austenite exceeds 10%, stretch flangeability and bendability are significantly lowered. For this reason, the volume ratio of retained austenite is 3 to 10%.

本発明の高強度鋼板および高強度溶融亜鉛めっき鋼板は、上述したフェライト、焼戻しマルテンサイト、マルテンサイト、残留オーステナイト以外の金属相としてパーライト、ベイナイトの1種または2種を含む可能性があるが、上記した相構成を満たしていれば問題はない。但し、延性および伸びフランジ性確保の観点からは、パーライトの面積率は3%以下とすることが望ましい。
・焼戻しマルテンサイトのビッカース硬度(m)とフェライトのビッカース硬度(f)の比(m)/(f):3.0以下、好ましくは2.0〜3.0
焼戻しマルテンサイトのビッカース硬度(m)とフェライトのビッカース硬度(f)の比(m)/(f)が3.0超では曲げ性が低下するので、硬度比(m)/(f)は3.0以下とする。一方、硬度比(m)/(f)が2.0未満では強度確保が難しくなる傾向があり、TSとELおよび曲げ性のバランスの観点から、硬度比(m)/(f)は2.0〜3.0とすることが好ましい。
The high-strength steel sheet and the high-strength hot-dip galvanized steel sheet of the present invention may contain one or two of pearlite and bainite as metal phases other than the above-described ferrite, tempered martensite, martensite, and retained austenite. There is no problem as long as the above phase structure is satisfied. However, from the viewpoint of securing ductility and stretch flangeability, the area ratio of pearlite is preferably 3% or less.
-Ratio (m) / (f) of Vickers hardness (m) of tempered martensite and Vickers hardness (f) of ferrite: 3.0 or less, preferably 2.0 to 3.0
When the ratio (m) / (f) of Vickers hardness (m) of tempered martensite to Vickers hardness (f) of ferrite exceeds 3.0, the bendability decreases, so the hardness ratio (m) / (f) is 3 0.0 or less. On the other hand, when the hardness ratio (m) / (f) is less than 2.0, it tends to be difficult to ensure the strength. From the viewpoint of balance between TS and EL and bendability, the hardness ratio (m) / (f) is 2. It is preferable to set it as 0-3.0.

次に、本発明の高強度鋼板および高強度溶融亜鉛めっき鋼板の好ましい製造条件について説明する。
本発明の鋼板を製造する場合、上述したような成分組成に調整した鋼を転炉などで溶製し、連続鋳造法などにより鋼スラブとする。この鋼スラブに熱間圧延を施して熱延鋼板とし、或いはさらに冷間圧延を施して冷延鋼板とし、前記熱延鋼板または冷延鋼板に連続焼鈍を施す。また、溶融亜鉛めっき鋼板を製造する場合には、この連続焼鈍後、溶融亜鉛めっきを施し、さらに必要に応じて、亜鉛めっきの合金化処理を施す。このような溶融亜鉛めっき鋼板の製造では、上記連続焼鈍を連続溶融亜鉛めっきラインで行ってもよい。
Next, preferable production conditions for the high-strength steel sheet and the high-strength hot-dip galvanized steel sheet according to the present invention will be described.
When manufacturing the steel plate of this invention, the steel adjusted to the component composition as mentioned above is melted in a converter or the like, and is made into a steel slab by a continuous casting method or the like. The steel slab is hot-rolled to obtain a hot-rolled steel sheet, or further cold-rolled to obtain a cold-rolled steel sheet, and the hot-rolled steel sheet or the cold-rolled steel sheet is subjected to continuous annealing. Moreover, when manufacturing a hot dip galvanized steel sheet, after this continuous annealing, hot dip galvanization is given, and also the galvanization alloying process is given as needed. In the manufacture of such a hot dip galvanized steel sheet, the continuous annealing may be performed in a continuous hot dip galvanizing line.

・熱間圧延条件
鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とする。熱延鋼板(または熱延鋼板を冷間圧延して得られた冷延鋼板)に焼鈍を施す際、Ac変態点以上に加熱することによりオーステナイトが生成する。特に熱延板組織におけるベイナイトやマルテンサイトなどの位置から優先的に生成するが、熱延鋼板の組織でベイナイトとマルテンサイトの面積率の合計が80%未満であると、焼鈍時のオーステナイトの生成が不均一となり、鋳造時にMn等の合金元素が偏析したような位置から優先的にオーステナイトが生成するようになる。焼鈍時に生成したオーステナイトは、その後の冷却、再加熱処理により一部が焼戻しマルテンサイトになるが、上記のように不均一に生成したオーステナイトは冷却時にマルテンサイト変態が起こりにくい、或いは再加熱による焼戻しが起こりにくいなどの理由から、本発明における最終組織を得ることが困難となる。このため、熱延鋼板のベイナイトとマルテンサイトの面積率の合計を80%以上とする。
-Hot rolling conditions A steel slab is hot-rolled to obtain a hot rolled steel sheet having a metal structure with a total area ratio of bainite and martensite of 80% or more. When annealing a hot-rolled steel sheet (or a cold-rolled steel sheet obtained by cold-rolling a hot-rolled steel sheet), austenite is generated by heating to the Ac 1 transformation point or higher. In particular, it is preferentially generated from the position of bainite or martensite in the hot-rolled sheet structure, but if the total area ratio of bainite and martensite is less than 80% in the structure of the hot-rolled steel sheet, austenite is generated during annealing. Becomes non-uniform, and austenite is preferentially generated from the position where alloy elements such as Mn are segregated during casting. Austenite generated during annealing partially becomes tempered martensite by subsequent cooling and reheating treatment, but austenite generated nonuniformly as described above is unlikely to undergo martensitic transformation during cooling or tempering by reheating. For example, it is difficult to obtain the final structure in the present invention for reasons such as being difficult to occur. For this reason, the sum total of the area ratio of the bainite and martensite of a hot-rolled steel sheet shall be 80% or more.

以上のような熱延鋼板の金属組織を得るために、熱間圧延では、Ar変態点以上の仕上圧延温度で圧延を終了した後、50℃/秒以上の平均冷却速度で冷却し、300〜550℃で巻取ることが好ましい。
仕上げ圧延終了温度がAr点未満或いは圧延後の平均冷却速度が50℃/秒未満では、圧延中または冷却中に過度にフェライトが生成して、熱延板組織をベイナイトとマルテンサイトの面積率の合計が80%以上とすることが困難となる。また、巻取り温度が550℃を超えると、巻取り後にフェライトやパーライトが生成し、熱延板組織をベイナイトとマルテンサイトの面積率の合計が80%以上とすることが困難となる。また、巻取り温度が300℃未満では、熱延鋼板の形状が悪化したり、熱延鋼板の強度が過度に上昇し、冷間圧延が困難となる。
In order to obtain the metal structure of the hot-rolled steel sheet as described above, in the hot rolling, after finishing the rolling at a finish rolling temperature not lower than the Ar 3 transformation point, the steel sheet is cooled at an average cooling rate of 50 ° C./second or higher. It is preferable to wind up at ˜550 ° C.
When the finish rolling finish temperature is less than Ar 3 points or the average cooling rate after rolling is less than 50 ° C./second, ferrite is excessively generated during rolling or cooling, and the hot rolled sheet structure has an area ratio of bainite and martensite. It is difficult to make the total of 80% or more. On the other hand, if the winding temperature exceeds 550 ° C., ferrite and pearlite are generated after winding, and it becomes difficult for the hot rolled sheet structure to have a total area ratio of bainite and martensite of 80% or more. Moreover, if coiling temperature is less than 300 degreeC, the shape of a hot-rolled steel plate will deteriorate, the intensity | strength of a hot-rolled steel plate will rise excessively, and cold rolling will become difficult.

・連続焼鈍条件
熱延鋼板またはこの熱延鋼板を冷間圧延して得られた冷延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持する。
連続焼鈍の加熱温度が750℃未満或いは保持時間が10秒未満では、焼鈍時のオーステナイトの生成が不十分となり、焼鈍冷却後に十分な量の低温変態相が確保できなくなる。また、加熱温度が900℃を超えると最終組織で20%以上のフェライトを確保することが困難となる。保持時間の上限は特に規定しないが、600秒以上の保持は効果が飽和する上、コストアップにつながるので、保持時間は600秒未満とすることが好ましい。
-Continuous annealing conditions When continuously annealing a hot-rolled steel sheet or a cold-rolled steel sheet obtained by cold rolling this hot-rolled steel sheet, after heating to 750-900 ° C and holding for 10 seconds or more, from 750 ° C to 10 ° C Cool to a temperature range of 100 to 350 ° C. at an average cooling rate of at least ° C./second, then reheat to 350 to 600 ° C. and hold for 10 to 600 seconds.
If the heating temperature for continuous annealing is less than 750 ° C. or the holding time is less than 10 seconds, austenite is not sufficiently generated during annealing, and a sufficient amount of low-temperature transformation phase cannot be secured after annealing cooling. On the other hand, if the heating temperature exceeds 900 ° C., it is difficult to secure 20% or more of ferrite in the final structure. The upper limit of the holding time is not particularly specified, but holding for 600 seconds or more saturates the effect and leads to an increase in cost. Therefore, the holding time is preferably less than 600 seconds.

750℃からの平均冷却速度が10℃/秒未満ではパーライトが生成し、延性および穴拡げ性が低下する。平均冷却速度の上限は特に規定しないが、冷却速度が速すぎると鋼板形状が悪化したり、冷却到達温度の制御が困難となるため、200℃/秒以下とすることが好ましい。冷却到達温度は本発明で最も重要な条件の一つである。冷却停止時にはオーステナイトの一部がマルテンサイトに変態し、残りは未変態のオーステナイトとなる。そこから再加熱した後(さらに必要に応じて、めっき処理またはめっき・合金化処理した後)、室温まで冷却することで、マルテンサイトは焼戻しマルテンサイトとなり、未変態オーステナイトは残留オーステナイトまたはマルテンサイトとなる。焼鈍からの冷却到達温度が低いほど、冷却中に生成するマルテンサイト量が増加し、未変態オーステナイト量が減少するため、冷却到達温度の制御により、最終的なマルテンサイトおよび残留オーステナイトと焼戻しマルテンサイトの量(面積率又は体積率)が決定される。冷却到達温度が350℃を超えると、冷却停止時のマルテンサイト変態が不十分で未変態オーステナイト量が多くなり、最終的なマルテンサイトまたは残留オーステナイトが過剰に生成し、穴拡げ性を低下させる。一方、冷却到達温度が100℃未満では、冷却中にオーステナイトがほとんどマルテンサイトに変態して未変態オーステナイト量が減少し、3%以上の残留オーステナイトが得られない。このため冷却到達温度は100〜350℃の範囲とする。   When the average cooling rate from 750 ° C. is less than 10 ° C./second, pearlite is produced, and ductility and hole expansibility are lowered. The upper limit of the average cooling rate is not particularly defined. However, if the cooling rate is too high, the shape of the steel sheet deteriorates and it becomes difficult to control the temperature at which the cooling reaches, and therefore it is preferably 200 ° C./second or less. The cooling ultimate temperature is one of the most important conditions in the present invention. When the cooling is stopped, a part of austenite is transformed into martensite, and the rest becomes untransformed austenite. After reheating from there (further, after plating or plating / alloying treatment if necessary), by cooling to room temperature, martensite becomes tempered martensite, and untransformed austenite becomes residual austenite or martensite. Become. The lower the temperature reached from the annealing, the lower the amount of martensite generated during cooling and the lower the amount of untransformed austenite. Therefore, the final martensite and residual austenite and tempered martensite are controlled by controlling the cooling temperature. Is determined (area ratio or volume ratio). When the cooling attainment temperature exceeds 350 ° C., the martensite transformation at the time of cooling stop is insufficient and the amount of untransformed austenite is increased, the final martensite or residual austenite is excessively generated, and the hole expandability is lowered. On the other hand, when the temperature reached by cooling is less than 100 ° C., austenite is almost transformed into martensite during cooling, and the amount of untransformed austenite is reduced, and 3% or more of retained austenite cannot be obtained. For this reason, cooling ultimate temperature shall be the range of 100-350 degreeC.

100〜350℃の温度域まで冷却した後、350〜600℃まで再加熱して10〜600秒保持することで、前記冷却時に生成したマルテンサイトが焼戻されて焼戻しマルテンサイトとなり、これにより穴拡げ性が向上し、さらに前記冷却時にマルテンサイトに変態しなかった未変態オーステナイトが安定化され、最終的に3%以上の残留オーステナイトが得られ、延性が向上する。再加熱保持による未変態オーステナイトの安定化のメカニズムについては詳細は不明であるが、未変態オーステナイトへのCの濃化が進み、オーステナイトが安定化されるものと考えられる。再加熱温度が350℃未満ではマルテンサイトの焼戻しおよびオーステナイトの安定化が不十分となり、穴拡げ性および延性が低下する。また、再加熱温度が600℃を超えると、冷却停止時の未変態オーステナイトがパーライトに変態し、最終的に3%以上の残留オーステナイトが得られなくなる。保持時間が10秒未満ではオーステナイトの安定化が不十分となり、また600秒を超えると冷却停止時の未変態オーステナイトがベイナイトに変態し、最終的に3%以上の残留オーステナイトが得られなくなる。このため再加熱温度は350〜600℃の範囲とし、その温度域での保持時間は10〜600秒とする。   After cooling to a temperature range of 100 to 350 ° C., reheating to 350 to 600 ° C. and holding for 10 to 600 seconds, the martensite generated during the cooling is tempered to become tempered martensite. Expandability is improved, and untransformed austenite that has not been transformed into martensite at the time of cooling is stabilized. Finally, 3% or more of retained austenite is obtained, and ductility is improved. Although the details of the mechanism of stabilization of untransformed austenite by reheating and holding are unknown, it is considered that the concentration of C in the untransformed austenite proceeds and the austenite is stabilized. If the reheating temperature is less than 350 ° C., the tempering of martensite and the stabilization of austenite are insufficient, and the hole expandability and ductility are lowered. On the other hand, when the reheating temperature exceeds 600 ° C., untransformed austenite at the time of cooling stop is transformed into pearlite, and finally 3% or more of retained austenite cannot be obtained. If the holding time is less than 10 seconds, the stabilization of austenite becomes insufficient, and if it exceeds 600 seconds, untransformed austenite at the time of cooling stop is transformed into bainite, and finally 3% or more of retained austenite cannot be obtained. Therefore, the reheating temperature is in the range of 350 to 600 ° C., and the holding time in that temperature range is 10 to 600 seconds.

・溶融亜鉛めっき処理条件
溶融亜鉛めっき処理の条件は特に限定しないが、溶融亜鉛めっき鋼板(GI)製造時は0.12〜0.22質量%、合金化溶融亜鉛めっき鋼板(GA)製造時は0.08〜0.18質量%の溶解Al量であって、浴温440〜500℃のめっき浴で行うことが好ましく、鋼板をめっき浴中に侵入させた後、ガスワイピングなどでめっき付着量を調整する。合金化溶融亜鉛めっき鋼板の製造時には、めっき付着量の調整後、450〜600℃まで加熱し、1〜30秒保持する合金化処理を行う。
なお、溶融亜鉛めっき処理後の鋼板(合金化溶融亜鉛めっき鋼板を含む)には、形状矯正、表面粗度等の調整のため調質圧延を加えてもよい。また、樹脂または油脂コーティング、各種塗装等の処理を施してよい。
また、溶融亜鉛めっき鋼板(合金化溶融亜鉛めっき鋼板を含む)の製造では、上述した熱延鋼板または冷延鋼板の連続焼鈍を、連続溶融亜鉛めっきラインで行うことが好ましい。
-Hot dip galvanizing treatment conditions The conditions of the hot dip galvanizing treatment are not particularly limited, but 0.12 to 0.22 mass% at the time of hot dip galvanized steel sheet (GI) production, and at the time of galvannealed steel sheet (GA) production. It is preferable that the amount of dissolved Al is 0.08 to 0.18% by mass, and is preferably performed in a plating bath having a bath temperature of 440 to 500 ° C. After the steel sheet has entered the plating bath, the amount of plating adhered by gas wiping or the like Adjust. At the time of manufacture of the galvannealed steel sheet, after adjusting the coating amount, the alloying treatment is performed by heating to 450 to 600 ° C. and holding for 1 to 30 seconds.
In addition, you may add temper rolling to the steel plate (including alloyed hot-dip galvanized steel plate) after the hot dip galvanizing treatment for adjustment of shape correction, surface roughness, and the like. Moreover, you may give processes, such as resin or oil-fat coating and various paintings.
Moreover, in the manufacture of hot dip galvanized steel sheets (including alloyed hot dip galvanized steel sheets), it is preferable to perform the above-described continuous annealing of hot-rolled steel sheets or cold-rolled steel sheets in a continuous hot-dip galvanizing line.

その他の製造条件は特に限定するものではないが、以下に好適例を示す。
・鋳造条件
使用する鋼スラブは、成分のマクロ偏析を防止するために連続鋳造法で製造するのが好ましいが、造塊法、薄スラブ鋳造法で製造してもよい。また、鋼スラブを製造したのち、一旦室温まで冷却し、その後再度加熱する従来法以外に、室温まで冷却することなく、温片のままで加熱炉に装入する、或いはわずかの保温をおこなった後に直ちに圧延する直送圧延、直接圧延などの省エネルギープロセスも問題なく適用できる。
Other manufacturing conditions are not particularly limited, but preferred examples are shown below.
Casting conditions The steel slab to be used is preferably produced by a continuous casting method in order to prevent macro segregation of components, but may be produced by an ingot-making method or a thin slab casting method. In addition, after manufacturing the steel slab, it was cooled to room temperature and then heated again, and then it was charged into the heating furnace as it was without cooling to room temperature, or a little warming was performed. Energy saving processes such as direct feed rolling and direct rolling, which are rolled immediately afterwards, can be applied without any problem.

・熱間圧延条件
スラブ加熱温度は1100℃以上が好ましい。エネルギー的には低温加熱が好ましいが、加熱温度が1100℃未満では、炭化物が十分に固溶できなかったり、圧延荷重の増大による熱間圧延時のトラブル発生の危険が増大するなどの問題が生じやすい。なお、酸化重量の増加にともなうスケールロスの増大などから、スラブ加熱温度は1300℃以下とすることが望ましい。
また、スラブ加熱温度を低くした場合の熱間圧延時のトラブルを防止するために、シートバーを加熱するいわゆるシートバーヒーターを活用してもよい。
-Hot rolling conditions The slab heating temperature is preferably 1100 ° C or higher. Low-temperature heating is preferable in terms of energy, but if the heating temperature is less than 1100 ° C., carbides cannot be sufficiently dissolved, and problems such as increased risk of trouble during hot rolling due to an increase in rolling load occur. Cheap. Note that the slab heating temperature is desirably 1300 ° C. or less because of an increase in scale loss accompanying an increase in oxidized weight.
Moreover, in order to prevent the trouble at the time of hot rolling at the time of making slab heating temperature low, you may utilize what is called a sheet bar heater which heats a sheet bar.

なお、熱間圧延工程では、熱間圧延時の圧延荷重を低減するために仕上圧延の一部または全部を潤滑圧延としてもよい。潤滑圧延を行うことは、鋼板形状の均一化、材質の均一化の観点からも有効である。なお、潤滑圧延の際の摩擦係数は0.25〜0.10の範囲とすることが好ましい。また、相前後するシートバー同士を接合し、連続的に仕上圧延する連続圧延プロセスとすることが好ましい。連続圧延プロセスを適用することは、熱間圧延の操業安定性の観点からも望ましい。
熱延鋼板に冷間圧延を施す場合には、好ましくは熱延鋼板表面の酸化スケールを酸洗により除去した後、冷間圧延に供して所定の板厚の冷延鋼板とする。酸洗条件や冷間圧延条件は特に制限されるものではなく、常法に従えばよい。冷間圧延の圧下率は40%以上とすることが好ましい。
In the hot rolling step, part or all of the finish rolling may be lubricated rolling in order to reduce the rolling load during hot rolling. Performing lubrication rolling is also effective from the viewpoint of uniform steel plate shape and uniform material. In addition, it is preferable to make the friction coefficient in the case of lubrication rolling into the range of 0.25-0.10. Moreover, it is preferable to set it as the continuous rolling process which joins the sheet | seat bars which precede and follow, and finish-rolls continuously. The application of the continuous rolling process is also desirable from the viewpoint of the operational stability of hot rolling.
When performing cold rolling on a hot-rolled steel sheet, preferably the oxidized scale on the surface of the hot-rolled steel sheet is removed by pickling, and then subjected to cold rolling to obtain a cold-rolled steel sheet having a predetermined thickness. Pickling conditions and cold rolling conditions are not particularly limited, and may be according to ordinary methods. The rolling reduction of cold rolling is preferably 40% or more.

表1に示す成分組成を有し、残部がFeおよび不可避的不純物よりなる鋼を転炉にて溶製し、連続鋳造法にて鋳片とした。得られた鋳片を表2および表3に示す条件で板厚3.0mmまで熱間圧延した。この熱延鋼板を酸洗後、板厚1.4mmまで冷間圧延して冷延鋼板とし、これを連続溶融亜鉛めっきライン(CGL)において表2および表3に示す条件で連続焼鈍した後、溶融亜鉛めっきを施した。また、一部の実施例については、板厚2.3mmまで熱間圧延した鋼板を酸洗し、この熱延鋼板を連続溶融亜鉛めっきラインにおいて表3に示す条件で連続焼鈍した後、溶融亜鉛めっきを施した。溶融亜鉛めっき温度は460℃とし、めっき後、520℃で合金化処理を行い、平均冷却速度10℃/秒で冷却した。また、一部の実施例では、合金化処理を行わない溶融亜鉛めっき鋼板を製造した。めっき付着量は片面当たり35〜45g/mとした。また、一部の実施例(No.36〜42)については、上述した冷延鋼板、熱延鋼板を連続焼鈍ライン(CAL)で連続焼鈍し、溶融亜鉛めっきを施すことなく製品鋼板とした。 Steel having the composition shown in Table 1 and the balance being Fe and unavoidable impurities was melted in a converter and made into a slab by a continuous casting method. The obtained slab was hot-rolled to a thickness of 3.0 mm under the conditions shown in Tables 2 and 3. After pickling this hot-rolled steel sheet, it is cold-rolled to a sheet thickness of 1.4 mm to obtain a cold-rolled steel sheet, which is continuously annealed under the conditions shown in Tables 2 and 3 in a continuous hot-dip galvanizing line (CGL), Hot dip galvanizing was performed. In some examples, the steel sheet hot-rolled to a thickness of 2.3 mm was pickled, and the hot-rolled steel sheet was continuously annealed under the conditions shown in Table 3 in a continuous hot-dip galvanizing line. Plating was applied. The hot dip galvanizing temperature was 460 ° C., and after the plating, alloying treatment was performed at 520 ° C., and cooling was performed at an average cooling rate of 10 ° C./second. Moreover, in some Examples, the hot dip galvanized steel plate which does not perform an alloying process was manufactured. The plating adhesion amount was 35 to 45 g / m 2 per side. Moreover, about some Examples (No. 36-42), the cold-rolled steel plate and hot-rolled steel plate mentioned above were continuously annealed by the continuous annealing line (CAL), and it was set as the product steel plate without performing hot dip galvanization.

得られた鋼板(非めっき鋼板)および溶融亜鉛めっき鋼板について、断面ミクロ組織、引張特性、伸びフランジ性(穴拡げ性)、曲げ性を測定・評価した。その結果を表4および表5に示す。
鋼板の断面ミクロ組織は、3%ナイタール溶液(3%硝酸+エタノール)で組織を現出し、走査型電子顕微鏡で深さ方向板厚1/4位置を観察して、撮影した組織写真を用いて画像解析処理(この画像解析処理は市販の画像処理ソフトを用いることができる)を行い、フェライト相の面積分率を定量化した。マルテンサイト面積率、焼戻しマルテンサイト面積率は、組織の細かさに応じて1000〜3000倍の適切な倍率のSEM写真を撮影し、画像処理ソフトで定量化した。
About the obtained steel plate (non-plated steel plate) and hot-dip galvanized steel plate, the cross-sectional microstructure, tensile properties, stretch flangeability (hole expandability), and bendability were measured and evaluated. The results are shown in Tables 4 and 5.
The cross-sectional microstructure of the steel sheet is revealed with a 3% nital solution (3% nitric acid + ethanol), and the position of the thickness in the depth direction 1/4 is observed with a scanning electron microscope. Image analysis processing (this image analysis processing can use commercially available image processing software) was performed, and the area fraction of the ferrite phase was quantified. The martensite area ratio and tempered martensite area ratio were quantified with image processing software by taking SEM photographs at an appropriate magnification of 1000 to 3000 times depending on the fineness of the structure.

残留オーステナイトの体積率は、鋼板を板厚方向の1/4面まで研磨し、この板厚1/4面の回折X線強度により求めた。入射X線にはMoKα線を使用し、残留オーステナイト相の{111}、{200}、{220}、{311}面とフェライト相の{110}、{200}、{211}面のピークの積分強度の全ての組み合わせについて強度比を求め、これらの平均値を残留オーステナイトの体積率とした。
フェライトと焼戻しマルテンサイトの硬度は、マイクロビッカース硬度計を用い、荷重1g、負荷時間15sで測定した。それぞれの相の中央付近を10粒子分測定し、平均値をその相の硬度とした。
また、熱延鋼板の断面ミクロ組織についても、3%ナイタール溶液(3%硝酸+エタノール)で組織を現出し、走査型電子顕微鏡で深さ方向板厚1/4位置を観察して、撮影した組織写真を用いて画像解析処理を行い、ベイナイト相とマルテンサイト相の面積率を定量化し、それらの合計を求めた。
The volume ratio of retained austenite was determined by polishing the steel plate to a ¼ surface in the plate thickness direction and diffracting X-ray intensity of the ¼ surface thickness. MoKα rays are used as incident X-rays, and the peaks of {111}, {200}, {220}, {311} planes of retained austenite and {110}, {200}, {211} planes of ferrite phases are used. Intensity ratios were determined for all combinations of integrated intensities, and the average value of these ratios was taken as the volume fraction of retained austenite.
The hardness of ferrite and tempered martensite was measured using a micro Vickers hardness meter at a load of 1 g and a load time of 15 s. The vicinity of the center of each phase was measured for 10 particles, and the average value was taken as the hardness of the phase.
Also, the cross-sectional microstructure of the hot-rolled steel sheet was photographed by revealing the structure with a 3% nital solution (3% nitric acid + ethanol), observing the depth direction thickness 1/4 position with a scanning electron microscope. Image analysis processing was performed using the structure photograph, the area ratio of the bainite phase and the martensite phase was quantified, and the sum of them was obtained.

引張特性は、引張方向が鋼板の圧延方向と直角方向となるようサンプル採取したJIS5号試験片を用いて、JIS−Z2241に準拠した引張試験を行い、TS(引張強さ)、EL(伸び)を測定し、強度と伸びの積(TS×EL)で表される強度−伸びバランスの値を求めた。
伸びフランジ性は、日本鉄鋼連盟規格JFST1001に準じた穴拡げ試験を行い、穴拡げ率λで評価した。
曲げ性は、圧延方向と直角方向に幅30mm×長さ120mmの短冊状の試験片を採取し、端部を表面粗さRyが1.6〜6.3sとなるように平滑にした後、押し曲げ法により90°の曲げ角度で曲げ試験を行い、亀裂やネッキングの生じない最小の曲げ半径を限界曲げ半径Rとして評価した。
Tensile properties are obtained by performing a tensile test in accordance with JIS-Z2241, using a JIS No. 5 test piece sampled so that the tensile direction is perpendicular to the rolling direction of the steel sheet, and TS (tensile strength) and EL (elongation). The strength-elongation balance value represented by the product of strength and elongation (TS × EL) was determined.
Stretch flangeability was evaluated by a hole expansion rate λ by conducting a hole expansion test in accordance with Japan Iron and Steel Federation standard JFST1001.
The bendability is obtained by collecting a strip-shaped test piece having a width of 30 mm and a length of 120 mm in a direction perpendicular to the rolling direction, and smoothing the end so that the surface roughness Ry is 1.6 to 6.3 s. A bending test was performed at a bending angle of 90 ° by the push bending method, and the minimum bending radius at which no crack or necking occurred was evaluated as the critical bending radius R.

表4および表5によれば、本発明例は、いずれもTS×EL:21000MPa・%以上、穴拡げ率λ:70%以上、限界曲げ半径Rと板厚tの比R/t:1以下が達成され、優れた強度・延性バランス、伸びフランジ性および曲げ性が得られている。これに対して比較例は、TS×EL、穴拡げ率λ、比R/tの1つ以上が劣っており、本発明例のような優れた強度・延性バランス、伸びフランジ性および曲げ性を兼ね備えた性能は得られない。   According to Tables 4 and 5, in all of the examples of the present invention, TS × EL: 21000 MPa ·% or more, hole expansion ratio λ: 70% or more, ratio of critical bending radius R to sheet thickness t R / t: 1 or less As a result, excellent strength / ductility balance, stretch flangeability and bendability are obtained. In contrast, the comparative example is inferior in one or more of TS × EL, hole expansion ratio λ, ratio R / t, and has excellent strength / ductility balance, stretch flangeability and bendability as in the present invention example. Combined performance cannot be obtained.

Figure 2010275627
Figure 2010275627

Figure 2010275627
Figure 2010275627

Figure 2010275627
Figure 2010275627

Figure 2010275627
Figure 2010275627

Figure 2010275627
Figure 2010275627

Claims (14)

C:0.05〜0.3質量%、Si:0.01〜2.5質量%、Mn:0.5〜3.5質量%、P:0.003〜0.100質量%、S:0.02質量%以下、Al:0.010〜1.5質量%を含有し、SiとAlの含有量の合計が0.5〜3.0質量%であり、残部が鉄および不可避的不純物からなる成分組成を有し、面積率でフェライトを20%以上、焼戻しマルテンサイトを10〜60%、マルテンサイトを0〜10%を含み、体積率で残留オーステナイトを3〜10%含み、焼戻しマルテンサイトのビッカース硬度(m)とフェライトのビッカース硬度(f)の比(m)/(f)が3.0以下である金属組織を有することを特徴とする加工性に優れた高強度鋼板。   C: 0.05-0.3 mass%, Si: 0.01-2.5 mass%, Mn: 0.5-3.5 mass%, P: 0.003-0.100 mass%, S: 0.02% by mass or less, Al: 0.010 to 1.5% by mass, the total content of Si and Al is 0.5 to 3.0% by mass, the balance being iron and inevitable impurities The composition comprises: 20% or more ferrite by area ratio, 10-60% tempered martensite, 0-10% martensite, 3-10% residual austenite by volume, and tempered martensite. A high-strength steel sheet excellent in workability, characterized by having a metal structure in which a ratio (m) / (f) of Vickers hardness (m) of a site to Vickers hardness (f) of a ferrite is 3.0 or less. さらに、Cr:0.005〜2.00質量%、Mo:0.005〜2.00質量%、V:0.005〜2.00質量%、Ni:0.005〜2.00質量%、Cu:0.005〜2.00質量%のなかから選ばれる1種または2種以上を含有することを特徴とする請求項1に記載の加工性に優れた高強度鋼板。   Furthermore, Cr: 0.005-2.00 mass%, Mo: 0.005-2.00 mass%, V: 0.005-2.00 mass%, Ni: 0.005-2.00 mass%, The high-strength steel sheet with excellent workability according to claim 1, comprising one or more selected from Cu: 0.005 to 2.00% by mass. さらに、Ti:0.01〜0.20質量%、Nb:0.01〜0.20質量%のなかから選ばれる1種または2種を含有することを特徴とする請求項1または2に記載の加工性に優れた高強度鋼板。   Furthermore, 1 or 2 types chosen from Ti: 0.01-0.20 mass% and Nb: 0.01-0.20 mass% are contained, The 1 or 2 characterized by the above-mentioned. High-strength steel sheet with excellent workability. さらに、B:0.0002〜0.005質量%を含有することを特徴とする請求項1〜3のいずれかに記載の加工性に優れた高強度鋼板。   Furthermore, B: 0.0002-0.005 mass% is contained, The high-strength steel plate excellent in workability in any one of Claims 1-3 characterized by the above-mentioned. さらに、Ca:0.0001〜0.005質量%、REM:0.0001〜0.005質量%のなかから選ばれる1種または2種を含有することを特徴とする請求項1〜4のいずれかに記載の加工性に優れた高強度鋼板。   Furthermore, 1 type or 2 types chosen from Ca: 0.0001-0.005 mass% and REM: 0.0001-0.005 mass% are contained, Any of Claims 1-4 characterized by the above-mentioned. High-strength steel sheet with excellent workability as described in Crab. 焼戻しマルテンサイトのビッカース硬度(m)とフェライトのビッカース硬度(f)の比(m)/(f)が2.0〜3.0であることを特徴とする請求項1〜5のいずれかに記載の加工性に優れた高強度鋼板。   6. The ratio (m) / (f) of Vickers hardness (m) of tempered martensite and Vickers hardness (f) of ferrite is 2.0 to 3.0. High-strength steel plate with excellent workability as described. 下地鋼板が請求項1〜6のいずれかに記載の鋼板からなることを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板。   A high-strength hot-dip galvanized steel sheet excellent in workability, wherein the base steel sheet is made of the steel sheet according to any one of claims 1 to 6. 請求項1〜5のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持した後、室温まで冷却することを特徴とする加工性に優れた高強度鋼板の製造方法。   A steel slab having the composition according to any one of claims 1 to 5 is hot-rolled to form a hot-rolled steel sheet having a metal structure with a total area ratio of bainite and martensite of 80% or more. When performing continuous annealing on the steel sheet, after heating to 750 to 900 ° C. and holding for 10 seconds or more, the steel sheet is cooled from 750 ° C. to a temperature range of 100 to 350 ° C. at an average cooling rate of 10 ° C./second or more, and then 350 to A method for producing a high-strength steel sheet excellent in workability, characterized by reheating to 600 ° C. and holding for 10 to 600 seconds and then cooling to room temperature. 請求項1〜5のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板を冷間圧延して冷延鋼板とし、この冷延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持した後、室温まで冷却することを特徴とする加工性に優れた高強度鋼板の製造方法。   A steel slab having the composition according to any one of claims 1 to 5 is hot-rolled to form a hot-rolled steel sheet having a metal structure with a total area ratio of bainite and martensite of 80% or more. The steel sheet is cold-rolled to form a cold-rolled steel sheet. When the cold-rolled steel sheet is subjected to continuous annealing, it is heated to 750 to 900 ° C. and held for 10 seconds or more, and then an average cooling rate of 750 ° C. to 10 ° C./second or more. After cooling to a temperature range of 100 to 350 ° C., then reheating to 350 to 600 ° C. and holding for 10 to 600 seconds, followed by cooling to room temperature, a method for producing a high-strength steel sheet having excellent workability . 熱間圧延工程では、Ar変態点以上の仕上圧延温度で圧延を終了した後、50℃/秒以上の平均冷却速度で冷却し、300〜550℃で巻取ることを特徴とする請求項8または9に記載の加工性に優れた高強度鋼板の製造方法。 The hot rolling process, after completion of the rolling at Ar 3 transformation point or more of the finish rolling temperature, cooling at an average cooling rate of more than 50 ° C. / sec, claim, characterized in that wound at 300 to 550 ° C. 8 Or the manufacturing method of the high strength steel plate excellent in workability of 9. 請求項1〜5のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持し、しかる後、溶融亜鉛めっきを施すことを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。   A steel slab having the composition according to any one of claims 1 to 5 is hot-rolled to form a hot-rolled steel sheet having a metal structure with a total area ratio of bainite and martensite of 80% or more. When performing continuous annealing on the steel sheet, after heating to 750 to 900 ° C. and holding for 10 seconds or more, the steel sheet is cooled from 750 ° C. to a temperature range of 100 to 350 ° C. at an average cooling rate of 10 ° C./second or more, and then 350 to A method for producing a high-strength hot-dip galvanized steel sheet excellent in workability, characterized in that it is reheated to 600 ° C. and held for 10 to 600 seconds, and then hot-dip galvanized. 請求項1〜5のいずれかに記載の成分組成を有する鋼スラブを熱間圧延して、ベイナイトとマルテンサイトの面積率の合計が80%以上の金属組織を有する熱延鋼板とし、この熱延鋼板を冷間圧延して冷延鋼板とし、この冷延鋼板に連続焼鈍を施すに際し、750〜900℃まで加熱して10秒以上保持した後、750℃から10℃/秒以上の平均冷却速度で100〜350℃の温度域まで冷却し、次いで350〜600℃まで再加熱して10〜600秒保持し、しかる後、溶融亜鉛めっきを施すことを特徴とする加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。   A steel slab having the composition according to any one of claims 1 to 5 is hot-rolled to form a hot-rolled steel sheet having a metal structure with a total area ratio of bainite and martensite of 80% or more. The steel sheet is cold-rolled to form a cold-rolled steel sheet. When the cold-rolled steel sheet is subjected to continuous annealing, it is heated to 750 to 900 ° C. and held for 10 seconds or more, and then an average cooling rate of 750 ° C. to 10 ° C./second or more. The steel is cooled to a temperature range of 100 to 350 ° C., then reheated to 350 to 600 ° C., held for 10 to 600 seconds, and then subjected to hot dip galvanization. Manufacturing method of galvanized steel sheet. 熱間圧延工程では、Ar変態点以上の仕上圧延温度で圧延を終了した後、50℃/秒以上の平均冷却速度で冷却し、300〜550℃で巻取ることを特徴とする請求項11または12に記載の加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。 The hot rolling step, after finishing rolling at a finish rolling temperature not lower than the Ar 3 transformation point, is cooled at an average cooling rate of 50 ° C / second or higher, and is wound at 300 to 550 ° C. Or the manufacturing method of the high intensity | strength hot-dip galvanized steel plate excellent in the workability of 12. 溶融亜鉛めっきを施した後、めっき合金化処理を行うことを特徴とする請求項11〜13のいずれかに記載の加工性に優れた高強度溶融亜鉛めっき鋼板の製造方法。   The method for producing a high-strength hot-dip galvanized steel sheet excellent in workability according to any one of claims 11 to 13, wherein a plating alloying treatment is performed after hot-dip galvanizing.
JP2010038035A 2009-04-27 2010-02-24 High-strength steel sheet and high-strength hot-dip galvanized steel sheet excellent in workability and methods for producing them Active JP5493986B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2010038035A JP5493986B2 (en) 2009-04-27 2010-02-24 High-strength steel sheet and high-strength hot-dip galvanized steel sheet excellent in workability and methods for producing them

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2009107659 2009-04-27
JP2009107659 2009-04-27
JP2010038035A JP5493986B2 (en) 2009-04-27 2010-02-24 High-strength steel sheet and high-strength hot-dip galvanized steel sheet excellent in workability and methods for producing them

Publications (2)

Publication Number Publication Date
JP2010275627A true JP2010275627A (en) 2010-12-09
JP5493986B2 JP5493986B2 (en) 2014-05-14

Family

ID=43422854

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2010038035A Active JP5493986B2 (en) 2009-04-27 2010-02-24 High-strength steel sheet and high-strength hot-dip galvanized steel sheet excellent in workability and methods for producing them

Country Status (1)

Country Link
JP (1) JP5493986B2 (en)

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014508854A (en) * 2010-12-27 2014-04-10 ポスコ Steel sheet for molded member having excellent ductility, molded member, and manufacturing method thereof
CN103805838A (en) * 2012-11-15 2014-05-21 宝山钢铁股份有限公司 High formability super strength cold-roll steel sheet and manufacture method thereof
CN103805840A (en) * 2012-11-15 2014-05-21 宝山钢铁股份有限公司 Hot galvanizing super-strength steel plate with high formability and manufacturing method thereof
JP2015113504A (en) * 2013-12-12 2015-06-22 Jfeスチール株式会社 High strength hot-dip galvanized steel sheet excellent in processability and method for manufacturing the same
WO2016113789A1 (en) * 2015-01-15 2016-07-21 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and production method thereof
WO2016113788A1 (en) * 2015-01-15 2016-07-21 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and production method thereof
JP2016524038A (en) * 2013-05-17 2016-08-12 エイケイ・スティール・プロパティーズ・インコーポレイテッドAk Steel Properties, Inc. High-strength steel showing good durability, and manufacturing method by quenching and distribution treatment with zinc bath
WO2017085841A1 (en) * 2015-11-19 2017-05-26 新日鐵住金株式会社 High strength hot-rolled steel sheet and method for producing same
CN106734246A (en) * 2016-11-21 2017-05-31 首钢京唐钢铁联合有限责任公司 Method for reducing chromatic aberration of cold-rolled dual-phase steel
JP2017519900A (en) * 2014-05-13 2017-07-20 ポスコPosco High-strength cold-rolled steel sheet having excellent ductility, hot-dip galvanized steel sheet, and production methods thereof
JP2017524813A (en) * 2014-06-17 2017-08-31 ジュニア, ゲーリー, エム. コーラ High-strength iron-based alloy, method for producing the iron-based alloy, and object obtained from the method
CN107406930A (en) * 2015-02-27 2017-11-28 杰富意钢铁株式会社 High strength cold rolled steel plate and its manufacture method
KR20180070895A (en) * 2016-12-19 2018-06-27 주식회사 포스코 High-strength steel having excellent bendability and stretch-flangeability and method for manufacturing same
KR20180120210A (en) 2016-03-31 2018-11-05 제이에프이 스틸 가부시키가이샤 Thin steel plate and coated steel sheet, method of manufacturing hot-rolled steel sheet, manufacturing method of cold-rolled full-hard steel sheet, manufacturing method of thin steel sheet and manufacturing method of coated steel sheet
KR20180120715A (en) 2016-03-31 2018-11-06 제이에프이 스틸 가부시키가이샤 Thin steel plate and coated steel sheet, method of manufacturing hot-rolled steel sheet, manufacturing method of cold-rolled full-hard steel sheet, manufacturing method of thin steel sheet and manufacturing method of coated steel sheet
CN110042269A (en) * 2012-07-19 2019-07-23 Jx日矿日石金属株式会社 High strength titanium copper foil and preparation method thereof
US10570475B2 (en) 2014-08-07 2020-02-25 Jfe Steel Corporation High-strength steel sheet and production method for same, and production method for high-strength galvanized steel sheet
US10662495B2 (en) 2014-08-07 2020-05-26 Jfe Steel Corporation High-strength steel sheet and production method for same, and production method for high-strength galvanized steel sheet
US10662496B2 (en) 2014-08-07 2020-05-26 Jfe Steel Corporation High-strength steel sheet and production method for same, and production method for high-strength galvanized steel sheet
WO2020179292A1 (en) * 2019-03-06 2020-09-10 日本製鉄株式会社 Hot rolled steel sheet
WO2020179295A1 (en) * 2019-03-06 2020-09-10 日本製鉄株式会社 Hot-rolled steel sheet
CN112760554A (en) * 2019-10-21 2021-05-07 宝山钢铁股份有限公司 High-strength steel with excellent ductility and manufacturing method thereof
US11091818B2 (en) 2015-12-23 2021-08-17 Posco High strength cold-rolled steel sheet and hot-dip galvanized steel sheet having excellent hole expansion, ductility and surface treatment properties, and method for manufacturing same
CN114829658A (en) * 2019-12-18 2022-07-29 Posco公司 High-strength steel sheet having excellent workability and method for producing same
CN115151673A (en) * 2020-02-28 2022-10-04 杰富意钢铁株式会社 Steel sheet, member, and method for producing same
WO2022257902A1 (en) * 2021-06-07 2022-12-15 宝山钢铁股份有限公司 Hot-dip galvanized steel plate and manufacturing method therefor
CN115698359A (en) * 2020-07-20 2023-02-03 日本制铁株式会社 Steel sheet and method for producing same
CN115698362A (en) * 2020-06-30 2023-02-03 杰富意钢铁株式会社 Steel sheet, member, and method for producing same
JP2023507956A (en) * 2019-12-18 2023-02-28 ポスコホールディングス インコーポレーティッド High-strength steel sheet with excellent workability and its manufacturing method
JP2023507953A (en) * 2019-12-18 2023-02-28 ポスコホールディングス インコーポレーティッド High-strength steel sheet with excellent workability and its manufacturing method
JP2023507951A (en) * 2019-12-18 2023-02-28 ポスコホールディングス インコーポレーティッド High-strength steel sheet with excellent workability and its manufacturing method
EP4079884A4 (en) * 2020-02-28 2023-05-24 JFE Steel Corporation Steel sheet, member, and methods respectively for producing said steel sheet and said member
EP4079883A4 (en) * 2020-02-28 2023-05-24 JFE Steel Corporation Steel sheet, member, and methods respectively for producing said steel sheet and said member
WO2024041536A1 (en) * 2022-08-23 2024-02-29 宝山钢铁股份有限公司 120-kg-grade cold-rolled low-alloy annealed dual-phase steel and manufacturing method therefor
US12116646B2 (en) 2020-03-11 2024-10-15 Nippon Steel Corporation Hot-rolled steel sheet

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001003150A (en) * 1999-04-21 2001-01-09 Kawasaki Steel Corp High tensile strength hot dip galvanized steel sheet excellent in ductility and its production
JP2003013177A (en) * 2001-07-03 2003-01-15 Kawasaki Steel Corp Hot-dip galvanized sheet steel with high ductility superior in press formability and strain aging hardening characteristics, and manufacturing method thereor
JP2003073773A (en) * 2001-08-31 2003-03-12 Kobe Steel Ltd High-strength steel sheet superior in workability and fatigue characteristic, and manufacturing method therefor
JP2005076078A (en) * 2003-08-29 2005-03-24 Kobe Steel Ltd High tensile strength steel sheet having excellent workability, and method of manufacturing the same
JP2005264323A (en) * 2004-02-18 2005-09-29 Jfe Steel Kk High strength steel sheet having excellent deep drawability and stretch flange formability and its production method
JP2006104532A (en) * 2004-10-06 2006-04-20 Nippon Steel Corp High strength thin steel sheet having excellent elongation and hole expansibility and method for producing the same
JP2008121092A (en) * 2006-11-15 2008-05-29 Jfe Steel Kk Steel material with excellent fatigue crack propagation resistance, and its manufacturing method

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001003150A (en) * 1999-04-21 2001-01-09 Kawasaki Steel Corp High tensile strength hot dip galvanized steel sheet excellent in ductility and its production
JP2003013177A (en) * 2001-07-03 2003-01-15 Kawasaki Steel Corp Hot-dip galvanized sheet steel with high ductility superior in press formability and strain aging hardening characteristics, and manufacturing method thereor
JP2003073773A (en) * 2001-08-31 2003-03-12 Kobe Steel Ltd High-strength steel sheet superior in workability and fatigue characteristic, and manufacturing method therefor
JP2005076078A (en) * 2003-08-29 2005-03-24 Kobe Steel Ltd High tensile strength steel sheet having excellent workability, and method of manufacturing the same
JP2005264323A (en) * 2004-02-18 2005-09-29 Jfe Steel Kk High strength steel sheet having excellent deep drawability and stretch flange formability and its production method
JP2006104532A (en) * 2004-10-06 2006-04-20 Nippon Steel Corp High strength thin steel sheet having excellent elongation and hole expansibility and method for producing the same
JP2008121092A (en) * 2006-11-15 2008-05-29 Jfe Steel Kk Steel material with excellent fatigue crack propagation resistance, and its manufacturing method

Cited By (71)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014508854A (en) * 2010-12-27 2014-04-10 ポスコ Steel sheet for molded member having excellent ductility, molded member, and manufacturing method thereof
CN110042269A (en) * 2012-07-19 2019-07-23 Jx日矿日石金属株式会社 High strength titanium copper foil and preparation method thereof
CN103805838A (en) * 2012-11-15 2014-05-21 宝山钢铁股份有限公司 High formability super strength cold-roll steel sheet and manufacture method thereof
CN103805840A (en) * 2012-11-15 2014-05-21 宝山钢铁股份有限公司 Hot galvanizing super-strength steel plate with high formability and manufacturing method thereof
US10287659B2 (en) 2012-11-15 2019-05-14 Baoshan Iron & Steel Co., Ltd. High-formability and super-strength cold-rolled steel sheet
US10100385B2 (en) 2012-11-15 2018-10-16 Baoshan Iron & Steel Co., Ltd. High-formability and super-strength hot galvanizing steel plate and manufacturing method thereof
CN103805840B (en) * 2012-11-15 2016-12-21 宝山钢铁股份有限公司 A kind of high formability galvanizing ultrahigh-strength steel plates and manufacture method thereof
JP2018178262A (en) * 2013-05-17 2018-11-15 エイケイ・スティール・プロパティーズ・インコーポレイテッドAk Steel Properties, Inc. Methods for processing steel sheet
JP2016524038A (en) * 2013-05-17 2016-08-12 エイケイ・スティール・プロパティーズ・インコーポレイテッドAk Steel Properties, Inc. High-strength steel showing good durability, and manufacturing method by quenching and distribution treatment with zinc bath
JP2015113504A (en) * 2013-12-12 2015-06-22 Jfeスチール株式会社 High strength hot-dip galvanized steel sheet excellent in processability and method for manufacturing the same
US10519526B2 (en) 2014-05-13 2019-12-31 Posco High-strength cold rolled steel sheet having excellent ductility, hot-dip galvanized steel sheet and method for manufacturing same
JP2017519900A (en) * 2014-05-13 2017-07-20 ポスコPosco High-strength cold-rolled steel sheet having excellent ductility, hot-dip galvanized steel sheet, and production methods thereof
JP2021046611A (en) * 2014-06-17 2021-03-25 ジュニア, ゲーリー, エム. コーラ High strength iron-based alloy, process for making the same, and article resulting therefrom
JP2017524813A (en) * 2014-06-17 2017-08-31 ジュニア, ゲーリー, エム. コーラ High-strength iron-based alloy, method for producing the iron-based alloy, and object obtained from the method
US10662496B2 (en) 2014-08-07 2020-05-26 Jfe Steel Corporation High-strength steel sheet and production method for same, and production method for high-strength galvanized steel sheet
US10662495B2 (en) 2014-08-07 2020-05-26 Jfe Steel Corporation High-strength steel sheet and production method for same, and production method for high-strength galvanized steel sheet
US10570475B2 (en) 2014-08-07 2020-02-25 Jfe Steel Corporation High-strength steel sheet and production method for same, and production method for high-strength galvanized steel sheet
JPWO2016113788A1 (en) * 2015-01-15 2017-04-27 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and manufacturing method thereof
CN107109571A (en) * 2015-01-15 2017-08-29 杰富意钢铁株式会社 High-strength hot-dip zinc-coated steel sheet and its manufacture method
JPWO2016113789A1 (en) * 2015-01-15 2017-04-27 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and manufacturing method thereof
JP6052472B2 (en) * 2015-01-15 2016-12-27 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and manufacturing method thereof
US10370737B2 (en) 2015-01-15 2019-08-06 Jfe Steel Corporation High-strength galvanized steel sheet
JP6052471B2 (en) * 2015-01-15 2016-12-27 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and manufacturing method thereof
WO2016113788A1 (en) * 2015-01-15 2016-07-21 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and production method thereof
WO2016113789A1 (en) * 2015-01-15 2016-07-21 Jfeスチール株式会社 High-strength hot-dip galvanized steel sheet and production method thereof
CN107406930A (en) * 2015-02-27 2017-11-28 杰富意钢铁株式会社 High strength cold rolled steel plate and its manufacture method
JPWO2017085841A1 (en) * 2015-11-19 2018-08-02 新日鐵住金株式会社 High strength hot-rolled steel sheet and manufacturing method thereof
WO2017085841A1 (en) * 2015-11-19 2017-05-26 新日鐵住金株式会社 High strength hot-rolled steel sheet and method for producing same
US10301697B2 (en) 2015-11-19 2019-05-28 Nippon Steel & Sumitomo Metal Corporation High strength hot rolled steel sheet and manufacturing method thereof
CN108350536A (en) * 2015-11-19 2018-07-31 新日铁住金株式会社 High tensile hot rolled steel sheet and its manufacturing method
US11091818B2 (en) 2015-12-23 2021-08-17 Posco High strength cold-rolled steel sheet and hot-dip galvanized steel sheet having excellent hole expansion, ductility and surface treatment properties, and method for manufacturing same
KR20180120210A (en) 2016-03-31 2018-11-05 제이에프이 스틸 가부시키가이샤 Thin steel plate and coated steel sheet, method of manufacturing hot-rolled steel sheet, manufacturing method of cold-rolled full-hard steel sheet, manufacturing method of thin steel sheet and manufacturing method of coated steel sheet
KR20180120715A (en) 2016-03-31 2018-11-06 제이에프이 스틸 가부시키가이샤 Thin steel plate and coated steel sheet, method of manufacturing hot-rolled steel sheet, manufacturing method of cold-rolled full-hard steel sheet, manufacturing method of thin steel sheet and manufacturing method of coated steel sheet
US11136642B2 (en) 2016-03-31 2021-10-05 Jfe Steel Corporation Steel sheet, plated steel sheet, method of production of hot-rolled steel sheet, method of production of cold-rolled full hard steel sheet, method of production of steel sheet, and method of production of plated steel sheet
US11136636B2 (en) 2016-03-31 2021-10-05 Jfe Steel Corporation Steel sheet, plated steel sheet, method of production of hot-rolled steel sheet, method of production of cold-rolled full hard steel sheet, method of production of steel sheet, and method of production of plated steel sheet
CN106734246A (en) * 2016-11-21 2017-05-31 首钢京唐钢铁联合有限责任公司 Method for reducing chromatic aberration of cold-rolled dual-phase steel
US10941468B2 (en) 2016-12-19 2021-03-09 Posco High tensile strength steel having excellent bendability and stretch-flangeability and manufacturing method thereof
KR20180070895A (en) * 2016-12-19 2018-06-27 주식회사 포스코 High-strength steel having excellent bendability and stretch-flangeability and method for manufacturing same
KR101889181B1 (en) * 2016-12-19 2018-08-16 주식회사 포스코 High-strength steel having excellent bendability and stretch-flangeability and method for manufacturing same
WO2018117500A1 (en) * 2016-12-19 2018-06-28 주식회사 포스코 High tensile strength steel having excellent bendability and stretch-flangeability and manufacturing method thereof
CN110073023B (en) * 2016-12-19 2021-02-26 Posco公司 High-tension steel excellent in bendability and stretch flangeability, and method for producing same
CN110073023A (en) * 2016-12-19 2019-07-30 Posco公司 Bendability and the high tension steel having excellent stretch flangeability and its manufacturing method
WO2020179292A1 (en) * 2019-03-06 2020-09-10 日本製鉄株式会社 Hot rolled steel sheet
KR102543407B1 (en) 2019-03-06 2023-06-14 닛폰세이테츠 가부시키가이샤 hot rolled steel
KR20210102418A (en) * 2019-03-06 2021-08-19 닛폰세이테츠 가부시키가이샤 hot rolled steel
WO2020179295A1 (en) * 2019-03-06 2020-09-10 日本製鉄株式会社 Hot-rolled steel sheet
JP6784343B1 (en) * 2019-03-06 2020-11-11 日本製鉄株式会社 Hot-rolled steel sheet
JP6784344B1 (en) * 2019-03-06 2020-11-11 日本製鉄株式会社 Hot-rolled steel sheet
US12123064B2 (en) 2019-03-06 2024-10-22 Nippon Steel Corporation Hot-rolled steel sheet
EP3936628A4 (en) * 2019-03-06 2022-10-26 Nippon Steel Corporation Hot rolled steel sheet
EP3936630A4 (en) * 2019-03-06 2022-11-02 Nippon Steel Corporation Hot-rolled steel sheet
CN112760554A (en) * 2019-10-21 2021-05-07 宝山钢铁股份有限公司 High-strength steel with excellent ductility and manufacturing method thereof
CN114829658A (en) * 2019-12-18 2022-07-29 Posco公司 High-strength steel sheet having excellent workability and method for producing same
CN114829658B (en) * 2019-12-18 2024-01-23 Posco公司 High-strength steel sheet excellent in workability and method for producing same
JP7554827B2 (en) 2019-12-18 2024-09-20 ポスコホールディングス インコーポレーティッド High-strength steel plate with excellent workability and manufacturing method thereof
JP2023507956A (en) * 2019-12-18 2023-02-28 ポスコホールディングス インコーポレーティッド High-strength steel sheet with excellent workability and its manufacturing method
JP2023507953A (en) * 2019-12-18 2023-02-28 ポスコホールディングス インコーポレーティッド High-strength steel sheet with excellent workability and its manufacturing method
JP2023507951A (en) * 2019-12-18 2023-02-28 ポスコホールディングス インコーポレーティッド High-strength steel sheet with excellent workability and its manufacturing method
JP7554828B2 (en) 2019-12-18 2024-09-20 ポスコホールディングス インコーポレーティッド High-strength steel plate with excellent workability and manufacturing method thereof
CN115151673B (en) * 2020-02-28 2024-04-19 杰富意钢铁株式会社 Steel sheet, member, and method for producing same
EP4079883A4 (en) * 2020-02-28 2023-05-24 JFE Steel Corporation Steel sheet, member, and methods respectively for producing said steel sheet and said member
EP4079884A4 (en) * 2020-02-28 2023-05-24 JFE Steel Corporation Steel sheet, member, and methods respectively for producing said steel sheet and said member
EP4079882A4 (en) * 2020-02-28 2023-05-24 JFE Steel Corporation Steel sheet, member, and methods respectively for producing said steel sheet and said member
CN115151673A (en) * 2020-02-28 2022-10-04 杰富意钢铁株式会社 Steel sheet, member, and method for producing same
US12116646B2 (en) 2020-03-11 2024-10-15 Nippon Steel Corporation Hot-rolled steel sheet
CN115698362B (en) * 2020-06-30 2024-05-14 杰富意钢铁株式会社 Steel sheet, member, and method for producing same
CN115698362A (en) * 2020-06-30 2023-02-03 杰富意钢铁株式会社 Steel sheet, member, and method for producing same
CN115698359B (en) * 2020-07-20 2024-03-29 日本制铁株式会社 Steel sheet and method for producing same
CN115698359A (en) * 2020-07-20 2023-02-03 日本制铁株式会社 Steel sheet and method for producing same
WO2022257902A1 (en) * 2021-06-07 2022-12-15 宝山钢铁股份有限公司 Hot-dip galvanized steel plate and manufacturing method therefor
WO2024041536A1 (en) * 2022-08-23 2024-02-29 宝山钢铁股份有限公司 120-kg-grade cold-rolled low-alloy annealed dual-phase steel and manufacturing method therefor

Also Published As

Publication number Publication date
JP5493986B2 (en) 2014-05-14

Similar Documents

Publication Publication Date Title
JP5493986B2 (en) High-strength steel sheet and high-strength hot-dip galvanized steel sheet excellent in workability and methods for producing them
JP6179461B2 (en) Manufacturing method of high-strength steel sheet
CA2762935C (en) High-strength galvannealed steel sheet having excellent formability and fatigue resistance and method for manufacturing the same
JP5821260B2 (en) High-strength hot-dip galvanized steel sheet excellent in formability and shape freezing property, and method for producing the same
JP5463685B2 (en) High-strength cold-rolled steel sheet excellent in workability and impact resistance and method for producing the same
JP5369663B2 (en) High-strength hot-dip galvanized steel sheet excellent in workability and manufacturing method thereof
JP5402007B2 (en) High-strength hot-dip galvanized steel sheet excellent in workability and manufacturing method thereof
JP5418047B2 (en) High strength steel plate and manufacturing method thereof
JP5786316B2 (en) High-strength hot-dip galvanized steel sheet excellent in workability and impact resistance and method for producing the same
JP5834717B2 (en) Hot-dip galvanized steel sheet having a high yield ratio and method for producing the same
JP4998756B2 (en) High-strength hot-dip galvanized steel sheet excellent in workability and manufacturing method thereof
JP5924332B2 (en) High-strength hot-dip galvanized steel sheet excellent in workability and manufacturing method thereof
WO2014020640A1 (en) High-strength hot-dip galvanized steel sheet having excellent moldability and shape fixability, and method for manufacturing same
JP5786317B2 (en) High-strength hot-dip galvanized steel sheet with excellent material stability and workability and method for producing the same
WO2011090184A1 (en) High-strength hot-dip galvanized steel sheet with excellent processability and spot weldability and process for producing same
JP7164024B2 (en) High-strength steel plate and its manufacturing method
JP5256690B2 (en) High-strength hot-dip galvanized steel sheet excellent in workability and impact resistance and method for producing the same
JP5509909B2 (en) Manufacturing method of high strength hot-rolled steel sheet
JP2010156031A (en) Hot dip galvanized high strength steel sheet having excellent formability, and method for producing the same
JP5256689B2 (en) High-strength hot-dip galvanized steel sheet excellent in workability and manufacturing method thereof
JP5853884B2 (en) Hot-dip galvanized steel sheet and manufacturing method thereof
JPWO2021079755A1 (en) High-strength steel plate and its manufacturing method
JP6119655B2 (en) High strength alloyed hot dip galvanized steel strip excellent in formability with small material variations in steel strip and method for producing the same

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20120727

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20131001

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20131128

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: 20140204

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20140217

R150 Certificate of patent or registration of utility model

Ref document number: 5493986

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250