JP5350252B2 - Process for producing flat steel products from steel forming a martensitic microstructure - Google Patents

Process for producing flat steel products from steel forming a martensitic microstructure Download PDF

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JP5350252B2
JP5350252B2 JP2009533821A JP2009533821A JP5350252B2 JP 5350252 B2 JP5350252 B2 JP 5350252B2 JP 2009533821 A JP2009533821 A JP 2009533821A JP 2009533821 A JP2009533821 A JP 2009533821A JP 5350252 B2 JP5350252 B2 JP 5350252B2
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hot
strip
rolled strip
rolled
cold
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JP2010508434A5 (en
JP2010508434A (en
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ハンマー，ブリギッテ
ヘラー，トーマス
ヴィルヘルム シュミッツ，ヨハン
ヴァンス，ヨッヘン
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ThyssenKrupp Steel Europe AG
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/041—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing involving a particular fabrication or treatment of ingot or slab
    • C21D8/0415—Rapid solidification; Thin strip casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0426—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0473—Final recrystallisation annealing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Metal Rolling (AREA)
  • Heat Treatment Of Steel (AREA)
  • Continuous Casting (AREA)

Abstract

The method for the production of flat steel products useful in automotive industry, comprises casting a steel into a cast strip having a thickness of 1-4 mm, hot-rolling the cast strip in-line into a hot-rolled strip having a thickness of higher than 1.5 mm in a continuous process at 900-1050[deg] C, and coiling the hot-rolled strip at 550-620[deg] C to obtain a hot-rolled strip, which has a minimum tensile strength R m of 1400 MPa and a minimum breaking elongation A 8 0 of 5%. The hot-rolled strip is cold-rolled with a thickness of 0.5-1.4 mm at 750-850[deg] C to obtain a cold-rolled strip. The method for the production of flat steel products useful in automotive industry, comprises casting a steel into a cast strip having a thickness of 1-4 mm, hot-rolling the cast strip in-line into a hot-rolled strip having a thickness of higher than 1.5 mm in a continuous process at 900-1050[deg] C, and coiling the hot-rolled strip at 550-620[deg] C to obtain a hot-rolled strip, which has a minimum tensile strength R m of 1400 MPa and a minimum breaking elongation A 8 0 of 5%. The steel forms a complex phase structure. The shaping degree is greater than 20%. The width of the hot-rolled strip is more than 1.600 mm. The hot-rolled strip is cold-rolled with a thickness of 0.5-1.4 mm at 750-850[deg] C to obtain a cold-rolled strip, which has a minimum tensile strength of 600 MPa and a minimum breaking elongation A 8 0 of 15%. The cold- or hot-rolled strip is provided with a metallic coating, which is galvanizing.

Description

発明の詳細な説明Detailed Description of the Invention

本発明は、高張力マルテンサイト鋼（hochfeste martensitischen Staehlen）から、フラット鋼生成物（Stahl-Flachprodukte；例えば、ストリップ又はシートメタルブランク）を製造する方法に関する。前記ＭＳ鋼は、多相鋼の群に属する。これらは、通常、ミクロ組織の相のタイプ、量、及び配置（Anordnung）によりその特性が決定される鋼に関する。従って、ミクロ組織中には、少なくとも2つの相（例えば、フェライト、マルテンサイト、ベイナイト）が存在する。その結果、これらは、通常の鋼と比較すると、優れた強度／成形性の組合せを有する。   The present invention relates to a process for producing flat steel products (Stahl-Flachprodukte; for example strips or sheet metal blanks) from high-tensile martensitic steel. The MS steel belongs to the group of multiphase steels. These usually relate to steels whose properties are determined by the type, amount, and arrangement of microstructure phases. Therefore, there are at least two phases (eg, ferrite, martensite, bainite) in the microstructure. As a result, they have an excellent strength / formability combination when compared to ordinary steel.

多相鋼は、これらの特殊な特徴のために、特に自動車製造にとって極めて興味深い。なぜなら、それらの強度が高いために、一方で、より小さい材料厚の使用が可能になると同時に、車両重量の削減を可能にし、そして、他方で、衝突の際の車体の安全性（衝突態様）を改良するからである。従って、ボディ全体の少なくとも均等な強度を有する多相鋼によって、前記多相鋼製の部品のシートメタル厚を、従来の鋼製のボディよりも減少させることができる。   Multiphase steels are particularly interesting for automobile manufacturing because of these special features. Because of their high strength, on the one hand, it is possible to use a smaller material thickness, while at the same time enabling a reduction in vehicle weight, and on the other hand, the safety of the vehicle body in the event of a collision (collision mode) It is because it improves. Accordingly, the sheet metal thickness of the multi-phase steel part can be reduced as compared with the conventional steel body by the multi-phase steel having at least equal strength of the entire body.

通常、多相鋼は、コンバータースチールミル（Konverterstahlwerk）中で溶融され、そして、連続鋳造機でスラブ又は薄スラブへ鋳造され、次に、熱間圧延ストリップへ熱間圧延されて、巻き取られる。この場合には、特定のミクロ組織フラクションを調節する目的で、熱間圧延後での熱間圧延ストリップの選択的に制御された冷却によって、熱間圧延ストリップの機械的特性を変化させることができる。熱間圧延ストリップを冷間圧延ストリップへ冷間圧延して、より薄いシートメタル厚を得ることもできる（ＥＰ０９１０６７５Ｂ１、ＥＰ０９６６５４７Ｂ１、ＥＰ１１６９４８６Ｂ１、ＥＰ１３１９７２５Ｂ１、ＥＰ１３９８３９０Ａ１）。   Usually, the multiphase steel is melted in a converter steel mill (Konverterstahlwerk) and cast into a slab or thin slab in a continuous caster and then hot rolled into a hot rolled strip and wound up. In this case, the mechanical properties of the hot-rolled strip can be changed by selectively controlled cooling of the hot-rolled strip after hot rolling in order to adjust the specific microstructure fraction. . It is also possible to cold roll a hot rolled strip into a cold rolled strip to obtain a thinner sheet metal thickness (EP0910675B1, EP0966547B1, EP1169486B1, EP13197725B1, EP1398390A1).

８００ＭＰａを超える引張強さを有する高張力多相鋼からフラット生成物を製造することについての更なる問題は、前記鋼を圧延する際に、高い圧延力を付与する必要があることである。前記要件のために、通常、一般に入手可能な現在の製造機では、前記タイプの鋼から製造される高張力熱間圧延ストリップが、自動車産業により現在要求される要件を十分に満たさない幅及び厚さでしか、製造できないということが結果として生じる。特に、従来の装置では、十分な幅を有する厚さの小さいストリップを非常に良好に製造することができない。更に、従来の方法によって、８００ＭＰａを超える引張強さを有する冷間圧延ストリップを多相鋼から製造することが実際に困難であることが分かっている。   A further problem with producing flat products from high-strength multiphase steels having a tensile strength in excess of 800 MPa is that when rolling the steel, it is necessary to impart a high rolling force. Because of the above requirements, current production machines that are generally available generally have a width and thickness that does not sufficiently meet the requirements currently required by the automotive industry for high-tensile hot-rolled strips made from said type of steel. Only then can it be produced. In particular, conventional devices cannot produce very thin strips with a sufficient width. Furthermore, it has proved practically difficult to produce cold-rolled strips with a tensile strength in excess of 800 MPa from multiphase steel by conventional methods.

多相鋼から鋼ストリップを製造するための代替的な方法が、欧州特許ＥＰ１０７２６８９Ｂ１（ＤＥ６０００９６１１Ｔ２）中に提案されている。薄い鋼ストリップを製造するこの公知方法によると、最初に、（以下、重量％で表示）Ｃ：０．０５及び０．２５％；Ｍｎ、Ｃｕ及びＮｉ：合計で０．５〜３％；Ｓｉ及びＡｌ：合計で０．１〜４％；Ｐ、Ｓｎ、Ａｓ及びＳｂ：合計で０．１％まで；Ｔｉ、Ｎｂ、Ｖ、Ｚｒ及び希土類金属元素（ＲＥＭ）：合計で０．３％未満；並びに、Ｃｒ、Ｍｏ及びＶ：それぞれ１％未満；残余鉄及び不可避の不純物を含む鋼メルトを、厚さ０．５〜１０ｍｍ（特に、１〜５ｍｍ）を有する鋳造ストリップへ鋳造する。続いて、２５％〜７０％の間の範囲にある変形度（Umformgrad）で、鋳造ストリップを熱間圧延ストリップへ１回又は複数回のパスでインラインに熱間圧延する。この場合、最終熱間圧延温度は、Ａｒ３温度を超える。熱間圧延の終了時点で、得られる熱間圧延ストリップは、次に、２つの工程で冷却される。前記冷却の最初の工程では、温度が４００〜５５０℃の間の範囲に達するまで、冷却速度５〜１００℃／秒が維持される。次に、前記温度で、熱間圧延ストリップを滞留時間保持する。前記滞留時間は、５％を超える残余オーステナイト含有量を有する鋼がベイナイト変態するために必要とされる時間である。この場合、パーライトの形成も避けられるべきである。所望のミクロ組織を得るのに十分な滞留時間後で、変態プロセスが第２冷却工程の始まりによって中断される。前記第２冷却工程では、熱間圧延ストリップを４００℃未満の温度にして、３５０℃未満の巻き取り温度でコイルに巻き取る。 An alternative method for producing steel strips from multiphase steel has been proposed in European patent EP 1072689B1 (DE 60009611T2). According to this known method of producing a thin steel strip, first (hereinafter expressed in weight percent) C: 0.05 and 0.25%; Mn, Cu and Ni: 0.5-3% in total; Si And Al: 0.1 to 4% in total; P, Sn, As and Sb: up to 0.1% in total; Ti, Nb, V, Zr and rare earth metal elements (REM): less than 0.3% in total And Cr, Mo and V: each less than 1%; a steel melt containing residual iron and inevitable impurities is cast into cast strips having a thickness of 0.5 to 10 mm (especially 1 to 5 mm). Subsequently, the cast strip is hot rolled inline in one or more passes to the hot rolled strip with a degree of deformation (Umformgrad) in the range between 25% and 70%. In this case, the final hot rolling temperature exceeds the Ar 3 temperature. At the end of hot rolling, the resulting hot rolled strip is then cooled in two steps. In the first step of cooling, a cooling rate of 5-100 ° C./sec is maintained until the temperature reaches a range between 400-550 ° C. The hot rolled strip is then held at that temperature. The residence time is the time required for a steel having a residual austenite content of more than 5% to undergo bainite transformation. In this case, the formation of pearlite should also be avoided. After a residence time sufficient to obtain the desired microstructure, the transformation process is interrupted by the beginning of the second cooling step. In the second cooling step, the hot-rolled strip is brought to a temperature of less than 400 ° C. and wound around the coil at a winding temperature of less than 350 ° C.

ＥＰ１０７２６８９Ｂ１に記載される方法では、ＴＲＩＰ特性（ＴＲＩＰ＝変態誘起塑性）を有し、そして、ベイナイトミクロ組織フラクションを有する熱間圧延ストリップを、多相鋼から単純な方法で製造することができる。前記鋼は、良好な成形性を有する比較的高い強度を有する。しかしながら、多くの用途（特に、自動車製造分野における）にとって、強度が不十分である。   In the method described in EP 1072689 B1, hot-rolled strips having TRIP properties (TRIP = transformation induced plasticity) and having a bainite microstructure fraction can be produced in a simple manner from multiphase steel. The steel has a relatively high strength with good formability. However, for many applications (especially in the field of automobile production) the strength is insufficient.

従って、本発明の目的は、非常に高張力なフラット鋼生成物を、少ない労力で、幾何学的寸法の広い範囲で、製造することを可能にする方法を提供することからなる。   The object of the invention therefore consists in providing a method which makes it possible to produce very high tension flat steel products with a small amount of effort and in a wide range of geometric dimensions.

前述の先行技術に基づいて、本発明によると、前記目的は、
以下の組成（重量％で表示）
Ｃ： ０．１５ 〜 ０．１９％
Ｍｎ： ０．８０ 〜 １．２０％
Ｐ： ≦ ０．０３０％
Ｓ： ≦ ０．００４％
Ｓｉ： ０．６０ 〜 １．００％
Ａｌ： ≦ ０．０５％
Ｎ： ≦ ０．００６０％
Ｃｒ： ０．３０ 〜 ０．６０％
Ｎｂ： ０．０４０〜 ０．０７０％
残余鉄及び不可避の不純物
を有し、そして、マルテンサイトミクロ組織を形成する鋼を、厚さ１〜４ｍｍを有する鋳造ストリップへ鋳造して；
９００〜１０５０℃の範囲にある最終熱間圧延温度、２０％を超える変形度で、前記鋳造ストリップを連続処理中にインラインで、０．５〜３．２ｍｍの範囲にある厚さを有する熱間圧延ストリップへ熱間圧延して；
前記熱間圧延ストリップを、多くとも３５０℃の巻き取り温度で巻き取り；そして、
５％の最小破断伸びＡ８０での、１４００ＭＰａの最小引張強さＲｍを有する熱間圧延ストリップを得る；
フラット鋼生成物の製造方法によって達成される。 According to the present invention, based on the aforementioned prior art, the object is
The following composition (expressed in% by weight)
C: 0.15 to 0.19%
Mn: 0.80 to 1.20%
P: ≦ 0.030%
S: ≦ 0.004%
Si: 0.60 to 1.00%
Al: ≦ 0.05%
N: ≦ 0.0060%
Cr: 0.30 to 0.60%
Nb: 0.040-0.070%
Casting steel having residual iron and inevitable impurities and forming a martensitic microstructure into a cast strip having a thickness of 1 to 4 mm;
Final hot rolling temperature in the range of 900-1050 ° C., hot deformation having a thickness in the range of 0.5-3.2 mm in-line during continuous processing of the cast strip at a degree of deformation greater than 20% Hot rolled into a rolling strip;
Winding the hot rolled strip at a winding temperature of at most 350 ° C; and
Obtaining a hot-rolled strip having a minimum tensile strength R m of 1400 MPa with a minimum breaking elongation A 80 of 5%;
This is achieved by a method for producing a flat steel product.

本発明は、特に高張力なマルテンサイト鋼を熱間圧延ストリップへ加工するためのストリップ鋳造の可能性を利用する。この場合、鋳造ストリップそれ自体が小さい厚さを有しているので、自動車製造の分野で特に必要とされる厚さの小さいフラット生成物を製造するために、前記ストリップの熱間圧延の過程で比較的低い変形度のみを維持することが必要である。従って、本発明の方法によって、相当する鋳造ストリップの初めの厚さを特定することによって、熱間圧延ストリップを問題なく製造することが可能である。前記熱間圧延ストリップは、最適な特性分布での最大厚さ１．５ｍｍを有し、そして、前記熱間圧延ストリップから、例えば、車両の支持体構造用の部品を製造することができる。   The present invention takes advantage of the possibility of strip casting to process particularly high-tensile martensitic steel into hot-rolled strips. In this case, the cast strip itself has a small thickness, so in the process of hot rolling of the strip to produce a thin product with a small thickness that is particularly required in the field of automobile production. It is necessary to maintain only a relatively low degree of deformation. Thus, by the method of the invention, it is possible to produce hot rolled strips without problems by specifying the initial thickness of the corresponding cast strip. The hot-rolled strip has a maximum thickness of 1.5 mm with an optimum distribution of properties, and parts from, for example, vehicle support structures can be produced from the hot-rolled strip.

熱間圧延間での変形度が低いために、このために必要とされる圧延力は、従来方法による熱間圧延スラブ又は薄スラブで必要とされる力よりも低く、その結果、幅の大きい熱間圧延ストリップ（従来方法で鋳造される同じ強度及び厚さを有する熱間圧延ストリップの幅よりも実質的に大きい）を、本発明の方法で問題なく製造することができる。従って、本発明によって、前記組成を有し、本発明により製造されるマルテンサイト鋼からなり、そして、１２００ｍｍを超える（特に、１６００ｍｍを超える）幅を有する高張力熱間圧延ストリップを確実に製造することができる。   Due to the low degree of deformation during hot rolling, the rolling force required for this is lower than that required for hot rolling slabs or thin slabs according to conventional methods, and as a result is wider. Hot rolled strips (substantially larger than the width of hot rolled strips of the same strength and thickness cast by conventional methods) can be produced without problems with the method of the present invention. Therefore, according to the present invention, a high-tensile hot-rolled strip having the above composition and made of martensitic steel manufactured according to the present invention and having a width exceeding 1200 mm (especially exceeding 1600 mm) is reliably produced. be able to.

前記利点とは別に、本発明方法に特有のそれらの特徴及びプロセス変数（例えば、熱間圧延最終温度、冷却、巻取り温度）のために、本発明により構成されるタイプの高張力鋼を加工するためのストリップ鋳造工程の本発明の適用は、本発明により処理されるタイプの重要な鋼組成の確実な鋳造の可能性（さらに、それらの凝固態様について）を提供する。従って、ストリップの鋳造に特有な、鋳造ストリップの非常に素早い凝固によって、従来の製造と比較すると、中央溶解（Mittenseigerungen）の出現のリスクを実質的に減少させることができ、その結果、本発明により製造される熱間圧延ストリップは、その断面及びその長さにわたって特に均一な特徴分布及びミクロ組織を有する。   Apart from the advantages mentioned above, high strength steels of the type constructed according to the invention are processed because of their characteristics and process variables specific to the method of the invention (for example, hot rolling final temperature, cooling, winding temperature). The application of the present invention of the strip casting process to provide the possibility of reliable casting of important steel compositions of the type treated according to the present invention (and their solidification aspects). Thus, the very rapid solidification of the cast strip, which is characteristic of the casting of the strip, can substantially reduce the risk of the appearance of a central melt (Mittenseigerungen) compared to conventional production, so that the present invention The hot rolled strip produced has a particularly uniform feature distribution and microstructure across its cross section and its length.

本発明の方法の更なる特別な利点は、例えば、ＥＰ１０７２６８９Ｂ１に記載されるように、冷却中断の必要の結果としての、熱間圧延後と巻き取り後との間に維持されるべき、熱間圧延ストリップの特別な冷却サイクルを追加することなく、本発明により製造される熱間圧延ストリップが、少なくとも１４００ＭＰａの高い強度を有することである。本発明の方法を実施する場合には、熱間圧延を比較的厳密に限定される温度枠で終了すること、そして、巻取りを正確に規定された温度範囲で実施すること、だけが保証される必要がある。単一工程の冷却がその合間に実施される。   A further special advantage of the method according to the invention is that the hot to be maintained between hot rolling and after winding as a result of the need for a cooling interruption, as described for example in EP 1072689 B1. Without adding a special cooling cycle of the rolled strip, the hot rolled strip produced according to the present invention has a high strength of at least 1400 MPa. When carrying out the method of the invention, it is only guaranteed that the hot rolling is terminated in a relatively strictly limited temperature window and that the winding is carried out in a precisely defined temperature range. It is necessary to Single step cooling is performed in between.

本発明の方法の更なる利点は、本発明により製造されるストリップの機械的特性の範囲における拡張を、冷却及び圧延条件を変化させることによって、単一の鋼分析に基づいて、達成することができることである。   A further advantage of the method of the invention is that an extension in the range of mechanical properties of the strip produced according to the invention can be achieved on the basis of a single steel analysis by changing the cooling and rolling conditions. It can be done.

本発明により製造される熱間圧延ストリップは、次の冷間圧延ストリップへの加工に特に適当である。従って、本発明の或る実際の実施態様では、熱間圧延ストリップが提供され、前記熱間圧延ストリップは、自動車車体製造用に必要とされる、厚さ０．５〜１．４ｍｍ（特に、０．７ｍｍ〜１．３ｍｍまで）を有する冷間圧延ストリップへ冷間圧延される。冷間圧延の間で生じる凝固を排除するために、冷間圧延ストリップを焼鈍温度７５０〜８５０℃で焼鈍することができる。この場合に、本発明の方法により製造される熱間圧延ストリップから製造される冷間圧延ストリップでは、最小引張強度８００ＭＰａを確実に保証することができる。同時に、冷間圧延ストリップの最小破断伸びＡ50は、１０％である。 The hot-rolled strip produced according to the invention is particularly suitable for processing into the next cold-rolled strip. Accordingly, in one actual embodiment of the present invention, a hot rolled strip is provided, the hot rolled strip having a thickness of 0.5 to 1.4 mm (especially required for automobile body manufacturing) Cold rolled to a cold rolled strip having a thickness of 0.7 mm to 1.3 mm. To eliminate the solidification that occurs during cold rolling, the cold rolled strip can be annealed at an annealing temperature of 750-850 ° C. In this case, the minimum tensile strength of 800 MPa can be reliably ensured in the cold rolled strip manufactured from the hot rolled strip manufactured by the method of the present invention. At the same time, the minimum breaking elongation A 50 of the cold rolled strip is 10%.

本発明の更なる有利な実施態様によると、冷間圧延ストリップは、それ自体が公知である方法により、金属コーティング（例えば、これを亜鉛コーティングであることができる）を提供される。   According to a further advantageous embodiment of the invention, the cold-rolled strip is provided with a metal coating (for example it can be a zinc coating) by methods known per se.

本発明を、模範的な実施態様に基づいて、以下に詳しく説明する。   The invention is described in detail below on the basis of exemplary embodiments.

本発明の効果を実証するために実施される試験において、表１に示される組成を有する本発明により構成される２つの鋼Ａ及びＢを溶融し、双ロール鋳造機（Zweiwalzengiess-Maschine）で、１．６ｍｍ厚の鋳造ストリップへそれぞれ鋳造した。

Figure 0005350252
In a test carried out to demonstrate the effectiveness of the present invention, two steels A and B constructed according to the present invention having the composition shown in Table 1 were melted in a twin roll caster (Zweiwalzengiess-Maschine), Each was cast into a 1.6 mm thick cast strip.
Figure 0005350252

ストリップを鋳造した後に、鋼Ａ及びＢから鋳造されたストリップを、最終熱間圧延温度ＷＥＴで、１．２５ｍｍの厚さを有する熱間圧延ストリップへインラインに直接熱間圧延した。続いて、それぞれの場合において得られた熱間圧延ストリップを、冷却工程中で巻き取り温度ＨＴまで冷却して巻き取った。巻き取り後に、鋼Ａ及びＢの各々から製造される熱間圧延ストリップは、それらの製造の間でそれぞれ維持される最終熱間温度ＷＥＴ及び巻き取り温度ＨＴと共に表２に示される、引張強さＲｍ及び破断伸びＡ８０を有していた。

Figure 0005350252
After casting the strip, the strip cast from steels A and B was hot rolled directly in-line into a hot rolled strip having a thickness of 1.25 mm at the final hot rolling temperature WET. Subsequently, the hot-rolled strip obtained in each case was cooled to the winding temperature HT during the cooling process and wound up. After winding, the hot-rolled strips produced from each of steels A and B have the tensile strengths shown in Table 2 together with the final hot temperature WET and the winding temperature HT maintained respectively during their production. It had R m and a breaking elongation a 80.
Figure 0005350252

巻き取り及びピックリング後で、鋼Ａから製造される熱間圧延ストリップを、０．７ｍｍ厚の冷間圧延ストリップへ冷間圧延して、７８０℃の温度でインラインに焼鈍して、ストリップを再結晶化した。   After winding and pickling, the hot rolled strip produced from steel A is cold rolled into a 0.7 mm thick cold rolled strip and annealed inline at a temperature of 780 ° C. Crystallized.

２１．８％の破断伸びＡ50での、この方法で得られる冷間圧延ストリップの引張強度Ｒｍは、６５４ＭＰａであった。 The tensile strength R m of the cold-rolled strip obtained in this way with a break elongation A 50 of 21.8% was 654 MPa.

Claims (9)

フラット鋼生成物の製造方法であって、
以下の組成（質量％で表示）
Ｃ： ０．１５ 〜 ０．１９％
Ｍｎ： ０．８０ 〜 １．２０％
Ｐ： ≦ ０．０３０％
Ｓ： ≦ ０．００４％
Ｓｉ： ０．６０ 〜 １．００％
Ａｌ： ≦ ０．０５％
Ｎ： ≦ ０．００６０％
Ｃｒ： ０．３０ 〜 ０．６０％
Ｎｂ： ０．０４０〜 ０．０７０％
残余鉄及び不可避の不純物
を有し、そして、マルテンサイトミクロ組織を形成する鋼を、厚さ１〜４ｍｍを有する鋳造ストリップへ鋳造して；
９００〜１０５０℃の範囲にある最終熱間圧延温度、２０％を超える変形度で、前記鋳造ストリップを連続処理中にインラインで、０．５〜３．２ｍｍの範囲にある厚さを有する熱間圧延ストリップへ熱間圧延して；
前記熱間圧延ストリップを、３５０℃以下の巻き取り温度で巻き取り；そして、
５％以上の破断伸びＡ８０ 及び１４００ＭＰａ以上の引張強さＲｍを有する熱間圧延ストリップを得る；
前記製造方法。 A method for producing a flat steel product comprising:
The following composition ( expressed in mass %)
C: 0.15 to 0.19%
Mn: 0.80 to 1.20%
P: ≦ 0.030%
S: ≦ 0.004%
Si: 0.60 to 1.00%
Al: ≦ 0.05%
N: ≦ 0.0060%
Cr: 0.30 to 0.60%
Nb: 0.040-0.070%
Casting steel having residual iron and inevitable impurities and forming a martensitic microstructure into a cast strip having a thickness of 1 to 4 mm;
Final hot rolling temperature in the range of 900-1050 ° C., hot deformation having a thickness in the range of 0.5-3.2 mm in-line during continuous processing of the cast strip at a degree of deformation greater than 20% Hot rolled into a rolling strip;
The hot-rolled strip, coiling at 3 50 ° C. below the coiling temperature; and,
Obtaining a hot-rolled strip with at least 5% or more of fracture elongation A 80 and 1400MPa the pull ChoTsutomu of R m;
The manufacturing method. 熱間圧延ストリップの幅が、１２００ｍｍを超えることを特徴とする、請求項１に記載の方法。 Width of the hot rolled strip, characterized the Turkey exceed 1200 mm, The method of claim 1. 熱間圧延ストリップの厚さが、１．５ｍｍ以下であることを特徴とする、請求項１又は２に記載の方法。 The thickness of the hot rolled strip is 1 . The method according to claim 1, wherein the method is 5 mm or less . 熱間圧延ストリップを、厚さ０．５〜１．４ｍｍを有する冷間圧延ストリップへ冷間圧延することを特徴とする、請求項１〜３のいずれか一項に記載の方法。   The method according to any one of claims 1 to 3, characterized in that the hot-rolled strip is cold-rolled into a cold-rolled strip having a thickness of 0.5 to 1.4 mm. 冷間圧延ストリップを、焼鈍温度７５０〜８５０℃で焼鈍することを特徴とする、請求項４に記載の方法。   The method according to claim 4, characterized in that the cold-rolled strip is annealed at an annealing temperature of 750-850 ° C. 冷間圧延ストリップの引張強さが、６００ＭＰａ以上であることを特徴とする、請求項４又は５に記載の方法。 Argument ChoTsutomu of cold-rolled strip, characterized in that at least 600 MPa, The method of claim 4 or 5. 冷間圧延ストリップが、１５％以上の破断伸びＡ５０を有することを特徴とする、請求項４〜６のいずれか一項に記載の方法。 Cold rolling the strip, characterized in that it has 15% or more of fracture elongation A 50, A method according to any one of claims 4-6. 熱間圧延又は冷間圧延ストリップに、金属コーティングを施すことを特徴とする、請求項１〜７のいずれか一項に記載の方法。   The method according to claim 1, wherein a metal coating is applied to the hot-rolled or cold-rolled strip. 金属コーティングが亜鉛コーティングであることを特徴とする、請求項８に記載の方法。   9. A method according to claim 8, characterized in that the metal coating is a zinc coating.
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