EP2383353B1 - High tensile steel containing Mn, steel surface product made from such steel and method for producing same - Google Patents

High tensile steel containing Mn, steel surface product made from such steel and method for producing same Download PDF

Info

Publication number
EP2383353B1
EP2383353B1 EP11164339.1A EP11164339A EP2383353B1 EP 2383353 B1 EP2383353 B1 EP 2383353B1 EP 11164339 A EP11164339 A EP 11164339A EP 2383353 B1 EP2383353 B1 EP 2383353B1
Authority
EP
European Patent Office
Prior art keywords
weight
content
strip
flat steel
maximum
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.)
Active
Application number
EP11164339.1A
Other languages
German (de)
French (fr)
Other versions
EP2383353A2 (en
EP2383353A3 (en
Inventor
Dr.-Ing. Jens-Ulrik Becker
Dr.-Ing. Jian Bian
Dr. Brigitte Hammer
Dr. Thomas Heller
Christian Höckling
Dr.-Ing. Harald Hofmann
Dipl.-Ing. Matthias Schirmer
Oliver Bülters
Thomas Rieger
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.)
ThyssenKrupp Steel Europe AG
Original Assignee
ThyssenKrupp Steel Europe AG
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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=44520636&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP2383353(B1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by ThyssenKrupp Steel Europe AG filed Critical ThyssenKrupp Steel Europe AG
Publication of EP2383353A2 publication Critical patent/EP2383353A2/en
Publication of EP2383353A3 publication Critical patent/EP2383353A3/en
Application granted granted Critical
Publication of EP2383353B1 publication Critical patent/EP2383353B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following 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
    • C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
    • 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
    • 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
    • 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
    • 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
    • C21D8/0478—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 surface treatment
    • 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

Definitions

  • DP dual-phase
  • CP complex-phase
  • MS martensitic steels
  • a problem in the development of high-strength steels is that their forming properties (elongation at break) usually deteriorate more and more with increasing strength.
  • An example of this effect is a high-strength dual-phase steel, which at a strength of 1000 MPa can only expect an A80 elongation at break of about 12%. The comparatively low elongation at break can cause the material to fail during component forming.
  • a method for producing hot strips of a formable, especially good cold deep drawable lightweight structural steel, which is to have a high tensile strength and TRIP and / or TWIP properties is known from WO 2005/061152 A1 known. According to this method, a molten steel in a horizontal strip casting plant close to the final dimensions and flow-smoothed and bend-free cast to a preliminary strip in the range between 6 and 15 mm and then fed to a further treatment.
  • a horizontal strip casting method is used for this purpose.
  • the steel used for this contains, in addition to iron and unavoidable impurities (in% by weight) C: 0.04 - 1.0%, Al: 0.05 - ⁇ 4.0%, Si: 0.05 - 6.0% , Mn 9.0-30.0% and optionally Cr: up to 6.5%, with Cr contents of 0.2-0.3% being given as preferred, Nb and V in contents of up to 0, 06% and Ti and Zr can be present in levels of up to 0.7%.
  • the effect of chromium is considered to stabilize the ⁇ -martensite and to improve the corrosion resistance.
  • higher Cr contents are recommended for Mn contents of 9-18%, while for Mn contents above 18%, lower Cr contents are considered sufficient.
  • the WO 2005/061152 A1 it indicates how this ratio should be set in practice.
  • the object of the invention was to provide a steel flat product with good strength and good ductility from a steel that can be produced more cost-effectively than the known high manganese steels and at the same time high elongation at break values and, consequently, a significantly improved Formability possesses.
  • a method for producing such a flat steel product should be specified.
  • microstructure of a steel flat product produced from such a steel according to the invention typically consists of 30-100% of hardening structures (martensite, tempered martensite or bainite), while the remainder of the structure is austenitic.
  • a steel according to the invention because of its Mn contents in an average content range, can be produced at significantly reduced alloying and production costs both during continuous casting production and during production via a strip casting process.
  • carbon firstly determines the strength of martensite and, secondly, the amount and the stability of the retained austenite.
  • the carbon content of Mn steels of the type according to the invention is below 0.5 wt .-%, with optimum properties arise when the C content to less than 0.2 wt .-%, in particular less than 0.1 wt .-%, is limited. However, if the carbon content is too low, the amount and stability of the remaining retained austenite will be affected. Therefore, the C content of a steel according to the invention is at least 0.02 wt .-%, in particular at least 0.03 wt .-%, for example at least 0.05 wt .-%.
  • Manganese is an austenite former. It retards the transformation of ferrite, pearlite and bainite and thus stabilizes austenite up to the martensite start temperature. Manganese promotes the formation of cubic or hexagonal distorted martensite ( ⁇ - or ⁇ -martensite). These manganese martensites are characterized by high strengths and a much higher toughness compared to C-induced cubic distorted ⁇ -martensite. If the manganese content is too low, bainite is formed on cooling, which results in lower strength and elongation at break. On the other hand, if the manganese content is too high, there is a risk that the entire austenite will remain stable up to room temperature.
  • the manganese content of 5-12% prescribed by the invention makes it possible to set a martensite matrix with a Residual austenite content in the microstructure. This effect occurs particularly reliably when the Mn content is at least 6% by weight or even at least 7% by weight, wherein optimization of the positive effects of manganese in a steel according to the invention can be achieved by limiting the upper limit of Mn Content is limited to 10% by weight, in particular less than 9% by weight, for example up to 8.5% by weight.
  • Aluminum and silicon are strong ferrite formers. Both elements counteract the influence of austenite formers C and Mn.
  • the essential task of the elements Si and Al in a steel according to the invention is to suppress the carbide precipitation in the martensite matrix and thus to promote the stability of the retained austenite.
  • Si and Al lead to solid solution hardening and reduce the specific gravity of the steel.
  • the Si and Al content is too low, carbide precipitation may not be effectively suppressed.
  • the contents of Si and Al are too high, the processing is made more difficult both by production by continuous casting and by production by a strip casting method.
  • the invention provides, the Si content to max. 1 wt .-%, wherein the positive effects of the presence of Si can be effectively used thereby, if the Si content of the steel according to the invention at least 0.05 wt .-%, in particular 0.1 wt .-%, is.
  • the negative effects of Si can thereby be excluded with particular certainty that the Si content is limited to 0.7% by weight, in particular 0.5% by weight.
  • the Al content can be set to at least 0.01% by weight, in particular 0.02% by weight, while negative influences of Al can be excluded with particular certainty if the Al content of a steel according to the invention is limited to 2% by weight, in particular 1% by weight.
  • the presence of copper, chromium and nickel fundamentally improves the resistance of a steel according to the invention to various corrosion mechanisms.
  • the positive effect of Cu and Ni can thereby be used with particular certainty by adding these elements having a total of at least> 0% by weight, in particular 0.1% by weight, to the steel according to the invention.
  • negative effects of the presence of Cu and / or Ni in steels of the invention are avoided by the fact that the content of Cu and Ni each max. 1 wt .-% is or the content of Cu and Ni in total to a maximum of 2 wt .-%, in particular 1 wt .-%, is limited.
  • the presence of Cr in a steel according to the invention specifically reduces the risk of the formation of stress corrosion cracking.
  • Cr contributes to the increase in strength. From a content of 0.1 wt .-% Cr these positive effects are observed, the positive effect of Cr then occurs particularly safe when the Cr content of the steel according to the invention at least 0.5 wt .-%, in particular at least 1 Wt .-%, is.
  • the Cr content of a steel according to the invention is limited to max. 4 wt .-% limited, because at higher levels Cr carbides can form, which can adversely affect the ductility of the steel. Such negative effects can be excluded by the fact that the Cr content to max. 2 wt .-% is limited.
  • the presence of Cr in a steel according to the invention has an effect if the Cr content is 1 to 2% by weight.
  • Ti, Nb and V which may be present in amounts of up to 0.5% by weight in a steel according to the invention, contribute to grain refining and strength enhancement. In total, above 0.5 wt .-% levels of Ti, Nb and V lead to no increase in this effect.
  • the strength-increasing effect of Ti, Nb and V can be used in a particularly accurate and resource-saving manner if the sum of the contents of these micro-alloying elements in a steel according to the invention is limited to 0.3% by weight, in particular 0.2% by weight , The positive effect of the micro-alloying elements mentioned here already sets in when the sum of their contents is at least 0.025% by weight. In the case of the presence of Ti, its content is advantageously reduced to max.
  • the austenitic structure can be additionally stabilized. This effect occurs already when the N content of a steel according to the invention is at least 0.002 wt .-%, in particular at least 0.0025 wt .-%, with an optimum effect results when the N content to max. 0.025 wt .-% is limited.
  • the P contents of a steel according to the invention are limited to a maximum of 0.05% by weight, preferably 0.03% by weight, in order to reliably exclude negative influences of this element.
  • the S content of a steel according to the invention is limited to max. 0.01 wt .-%, in particular 0.005 wt .-%, limited.
  • the alloy concept according to the invention is adapted so that the formation of hardened structures with or without retained austenite in the hot strip is made possible.
  • the martensite start temperature M S of a steel alloyed in the context of the invention is above and the martensite finish temperature M F of a steel assembled according to the invention is below the room temperature.
  • the castability of Mn steels according to the invention is improved as a result of the reduction in the Mn content.
  • a first possibility of warm strip production consists of conventional continuous casting.
  • an inventive steel proves to be particularly advantageous because it allows a lower hot strip thickness of less than ⁇ 2.5 mm. This is due to the fact that its deformation resistance is significantly reduced as a result of lowering the Mn content compared to conventional high-manganese steel.
  • Mn steels by strip casting.
  • hot strip thicknesses of less than 2.0 mm can be achieved.
  • the annealing of the hot strip sets the higher austenite content. Thereafter, the strength decreases, and the elongation at break increases significantly.
  • hot strip annealing up to 70% austenite is adjusted according to the analysis concept, which is mainly responsible for improving the elongation at break. Since a martensite matrix is present in the unannealed hot strip, it is difficult to process it directly to cold strip. Thus, hot strip annealing may also serve the purpose of debonding the hot strip for cold rolling. For the hot strip annealing both a bell annealing and a continuous annealing comes into question.
  • Cold rolling the annealed or unannealed hot strip further reduces strip thickness and improves strip flatness.
  • the subsequent annealing removes the strain hardening for the component production and leads to the optimal microstructure setting with increased austenite content.
  • Both the annealed hot strip and the annealed cold strip can be either electrolytic or through Hot dip galvanizing (following the cold strip annealing) or be refined by other coil coating. It is also possible to provide the respective steel strip obtained with an organic coating.
  • the desired structure of a steel according to the invention with typically 30-100% hardening structure (martensite, tempered martensite or bainite) and the remainder austenite can be achieved by thermoforming and quenching the steel.
  • a molten steel containing, in addition to iron and unavoidable impurities (in% by weight) 0.1% C, 10% Mn, 0.4% Si, 0.008% N, 1.6% Al and 2% Cr is in continuous casting potted and hot rolled at a hot rolling end temperature ET of 900 ° C to a hot strip, which has been then reeled at a reel temperature HT of 650 ° C.
  • the hot strip thus obtained had a tensile strength Rm of 1400 MPa and an elongation at break A80 of 7%.
  • the residual austenite content of his structure was 14%.
  • a molten steel containing 0.1% C, 10% Mn, 0.4% Si, 0.008% N, 1.6% Al and 1.6% Cr besides iron and unavoidable impurities (in wt%) cast in a strip casting machine to a cast strip and hot rolled at a hot rolling end temperature ET of 900 ° C to a hot strip, which has been then reeled at a reel temperature HT of 650 ° C. Subsequently, a bell annealing has been carried out.
  • the tape thus obtained had a tensile strength Rm of 990 MPa and an elongation at break A50 of 27.5%.
  • the residual austenite of the obtained hot strip was 60% after annealing.
  • a hot strip which, in addition to iron and unavoidable impurities, consists of (in% by weight) 0.1% C, 7% Mn, 0.13% Si, 0.02% Al, 1.5% Cr, 0.18% Ni , 0.13% Cu, 0.02% N and 0.079% V, was subjected to bell annealing at an annealing temperature of 650 ° C over an annealing time of 40 hours.
  • the annealed hot strip had a tensile strength Rm of 1030 MPa and an elongation at break A50 of 23%.
  • the austenite content of his fabric was 30%.
  • a hot strip containing, in addition to iron and unavoidable impurities (in% by weight) 0.1% C, 7% Mn, 0.13% Si, 0.02% Al, 0.6% Cr, 0.18% Ni, 0.13% Cu, 0.02% N, and 0.079% V was cold rolled to a total deformation of 50% and then annealed at 680 ° C annealing temperature.
  • the tensile strength Rm of the obtained cold-rolled strip was 1120 MPa at an elongation at break A50 of 21%.
  • the austenite content of the microstructure was 30%.
  • the hot strip thus obtained had a tensile strength Rm of 1345 MPa and an elongation at break A80 of 5%.
  • the residual austenite content of his structure was 5.5%.
  • the hot strip obtained according to Example 5 is over an annealing time of 10 min. subjected to a hot strip annealing at 300 ° C.
  • the annealed hot strip had a tensile strength Rm of 1100 MPa at an elongation at break A80 of 8%.
  • a composite according to Example 2 hot strip is over a glow time of 10 min. subjected to a hot strip annealing at 300 ° C.
  • the annealed hot strip had a tensile strength Rm of 1300 MPa at an elongation at break A80 of 8%.
  • a hot strip consisting of (in wt%) 0.1% C, 7% Mn, 0.20% Si, 0.01% N and 2.6% Cr besides iron and unavoidable impurities is over three minutes subjected to annealing at 920 ° C, then transferred within 7 s in a quenching tank and quenched there in water. Alternatively, deterrence in oil would have been possible with the same result. After quenching, its tensile strength Rm was 1450 MPa with an elongation at break A80 of 11%. The product RmxA80 was therefore about 16,000 MPa x%.
  • the fabric of this way obtained hot strip consisted of cubic distorted ⁇ -martensite and low volume fractions of about 5% each of austenite and hexagonal distorted ⁇ martensite.
  • a hot strip containing, in addition to iron and unavoidable impurities (in% by weight) 0.1% C, 7% Mn, 0.13% Si, 0.02% Al, 1.5% Cr, 0.18% Ni, 0.13% Cu, 0.002% N and 0.08% V was cold rolled into a cold strip and then hot dip galvanized.
  • the galvanized cold strip had a tensile strength Rm of 1300 MPa at an elongation at break A50 of 15%.
  • the content of retained austenite in the structure of the obtained cast strip was 20%.
  • a hot strip containing, in addition to iron and unavoidable impurities (in% by weight) 0.08% C, 8% Mn, 0.15% Si, 0.02% Al, 1% Cr, 0.2% Ni, 0, 15% Cu, 0.015% N and 0.06% V was cold rolled into a cold strip and then subjected to bell annealing at an annealing temperature of 550 ° C. After annealing, its tensile strength Rm was 1080 MPa and its elongation at break A50 was 25%. The proportion of retained austenite in the structure of the cast strip after annealing was 30%.
  • a steel sheet containing, in addition to iron and unavoidable impurities (in% by weight), 0.05% C, 0.06% Si, 1.1% Cr, 0.01% N and 10% Mn is within three Heated to 920 ° C minutes. Subsequently, the sheet has been transferred within 7 s in each case a quenching tank in which it has been quenched in oil or water.
  • the oil quenched steel had a tensile strength Rm of 1390 MPa at a breaking elongation A80 of 12%. Accordingly, the product Rm * A was 16,680 MPa%.
  • the quenched steel in water had a tensile strength Rm of 1350 MPa at a breaking elongation A80 of 12%.
  • the product Rm * A was accordingly 16200 MPa% for the water quenched steel.
  • the microstructure of the steel consisted of cubically distorted ⁇ -martensite and low volume contents of tough austenite (about 4%) and hexagonal distorted ⁇ -martensite (about 6%).
  • a steel sheet containing, in addition to iron and unavoidable impurities (in% by weight), 0.05% C, 10% Mn, 0.06% Si, 0.009% N, 1.1% Cr and 1% Ni is within heated to 920 ° C for three minutes. Subsequently, the sheet has been transferred within 7 s in each case a quenching tank in which it has been quenched in oil or water.
  • the oil quenched steel had a tensile strength Rm of 1315 MPa at an elongation at break A80 of 12.1%.
  • the product Rm * A was accordingly 15910 MPa%.
  • the water-quenched steel had a tensile strength Rm of 1285 MPa at a breaking elongation A80 of 12.3%.
  • the product Rm * A was therefore 15810 MPa%.
  • the microstructure of the steel was cubic distorted ⁇ -martensite and low Volume contents of tough austenite (about 7%) and hexagonal distorted ⁇ -martensite (about 5%).
  • the oil quenched steel had a tensile strength Rm of 1350 MPa at an elongation at break A80 of 10.8%. Accordingly, the product Rm * A was 14580 MPa%.
  • the water-quenched steel had a tensile strength Rm of 1350 MPa at an elongation at break A80 of 10.6%. For the water-quenched steel, the product Rm * A was 14310 MPa%.
  • the microstructure of the steel consisted of cubically distorted ⁇ -martensite and low volume contents of tough austenite (about 12%).
  • the procedure according to the invention achieves an improved combination of component strength and residual deformation capacity, which is characterized by high values of the product of tensile strength and respective elongation at break compared to the state of the art for hot-formed highest-strength materials.

Description

Für den modernen Fahrzeugbau werden in zunehmendem Maße höherfeste Stähle wie Dualphasen (DP)-Stähle, Complexphasen (CP)-Stähle, TRIP-Stähle oder Martensitstähle (MS)-Stähle eingesetzt.Increasingly high-strength steels such as dual-phase (DP) steels, complex-phase (CP) steels, TRIP steels or martensitic steels (MS) steels are increasingly used for modern vehicle construction.

Durch die hohe Festigkeit dieser Stähle erhöht sich die Fahrsicherheit. Zugleich können immer leichtere Autokarosserien gestaltet werden, die aufgrund ihres verminderten Gewichts und der damit einhergehenden Einsparung an benötigter Antriebsenergie besonders umweltfreundlich sind.The high strength of these steels increases driving safety. At the same time lighter car bodies can be designed, which are particularly environmentally friendly due to their reduced weight and the associated savings in required drive energy.

Ein Problem bei der Entwicklung hochfester Stähle besteht darin, dass sich ihre Umformeigenschaften (Bruchdehnung) üblicherweise mit steigender Festigkeit immer mehr verschlechtert. Ein Beispiel für diesen Effekt ist ein hochfester Dualphasen-Stahl, der bei einer Festigkeit von 1000 MPa nur noch eine Bruchdehnung A80 von ca. 12 % erwarten lässt. Die vergleichbar geringe Bruchdehnung kann dazu führen, dass der Werkstoff bei der Bauteilumformung versagt.A problem in the development of high-strength steels is that their forming properties (elongation at break) usually deteriorate more and more with increasing strength. An example of this effect is a high-strength dual-phase steel, which at a strength of 1000 MPa can only expect an A80 elongation at break of about 12%. The comparatively low elongation at break can cause the material to fail during component forming.

Die Entwicklung von hochmanganhaltigen Stählen, d.h. Stählen mit Mn-Gehalten von mehr als 15 Gew.-%, zielte deshalb darauf ab, eine hohe Festigkeit mit hervorragender Umformbarkeit zu kombinieren. Bei einer Festigkeit von 1000 MPa bietet dieses Werkstoffkonzept eine Bruchdehnung A80 von 50 %. Jedoch sind diese Werkstoffkonzepte aufgrund des hohen Mangangehalts und den vergleichbar aufwändigen Erzeugungsprozessen sehr kostenintensiv.The development of high manganese steels, ie steels with Mn contents of more than 15 wt .-%, therefore, aimed at a high strength with excellent formability to combine. With a strength of 1000 MPa, this material concept offers an elongation at break A80 of 50%. However, these material concepts are very cost intensive due to the high manganese content and the comparatively complex production processes.

Aus der WO 2007/000156 A1 sind Beispiele für hochfeste austenitisch-martensitische Leichtbaustähle bekannt, die mit Chrom, Silizium, Nickel, Mangan und Aluminium legiert sind und eine Zugfestigkeit von > 800 - 1200 MPa bei einer Bruchdehnung > 25 % aufweisen. Bei Mn-Gehalten von (in Gew.-%) > 2,5 und < 30 %, Cr-Gehalten von > 0,5 und < 18 %, einem Si-Gehalt von > 1 % und < 4 % und einem Al-Gehalt von > 0,05 und < 4 % sollen ein Chrom- und ein Nickel-Äquivalent in Abhängigkeit von den jeweiligen Gehalten an Cr, Mo, Si, W, Mn, N, Co, Cu und Al jeweils so eingestellt werden, dass für die beiden Äquivalente angegebene Grenzwertpaare eingehalten werden. Konkret weisen die Beispiele, die diesen Anforderungen gerecht werden, jeweils hohe Si-Gehalte in Kombination mit jeweils hohen Ni-Gehalten und variierten Cr-Gehalten auf.From the WO 2007/000156 A1 Examples of high-strength austenitic-martensitic lightweight steels are known, which are alloyed with chromium, silicon, nickel, manganese and aluminum and have a tensile strength of> 800 - 1200 MPa with an elongation at break> 25%. At Mn contents of (in% by weight)> 2.5 and <30%, Cr contents of> 0.5 and <18%, an Si content of> 1% and <4% and an Al content of Content of> 0.05 and <4%, a chromium and a nickel equivalent, depending on the respective contents of Cr, Mo, Si, W, Mn, N, Co, Cu and Al should be respectively adjusted so that the two equivalents specified limit pairs are met. In concrete terms, the examples that meet these requirements each have high Si contents in combination with high Ni contents and varied Cr contents.

Ein Verfahren zum Erzeugen von Warmbändern aus einem umformbaren, insbesondere gut kalt tiefziehfähigen Leichtbaustahl, der eine hohe Zugfestigkeit und TRIP- und/oder TWIP-Eigenschaften besitzen soll, ist aus der WO 2005/061152 A1 bekannt. Gemäß diesem Verfahren wird eine Stahlschmelze in einer horizontalen Bandgießanlage endabmessungsnah sowie strömungsberuhigt und biegefrei zu einem Vorband im Bereich zwischen 6 und 15 mm vergossen und anschließend einer Weiterbehandlung zugeführt.A method for producing hot strips of a formable, especially good cold deep drawable lightweight structural steel, which is to have a high tensile strength and TRIP and / or TWIP properties, is known from WO 2005/061152 A1 known. According to this method, a molten steel in a horizontal strip casting plant close to the final dimensions and flow-smoothed and bend-free cast to a preliminary strip in the range between 6 and 15 mm and then fed to a further treatment.

Konkret wird dazu ein Horizontal-Bandgießverfahren eingesetzt. Der dazu verwendete Stahl enthält neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) C: 0,04 - 1,0 %, Al: 0,05 - < 4,0 %, Si: 0,05 - 6,0 %, Mn 9,0 - 30,0 % sowie optional Cr: bis 6,5 %, wobei Cr-Gehalte von 0,2 - 0,3 % als bevorzugt angegeben sind, Nb und V in Gehalten von in Summe bis zu 0,06 % und Ti und Zr in Gehalten von in Summe bis zu 0,7 % vorhanden sein können. Die Wirkung von Chrom wird dabei darin gesehen, dass es den ε-Martensit stabilisiert und die Korrosionsbeständigkeit verbessert. Zu diesem Zweck werden höhere Cr-Gehalte bei Mn-Gehalten von 9 - 18 % empfohlen, während bei Mn-Gehalten von über 18 % niedrigere Cr-Gehalte für ausreichend gehalten werden. An keiner Stelle der WO 2005/061152 A1 wird allerdings angegeben, wie dieses Verhältnis konkret eingestellt werden soll.In concrete terms, a horizontal strip casting method is used for this purpose. The steel used for this contains, in addition to iron and unavoidable impurities (in% by weight) C: 0.04 - 1.0%, Al: 0.05 - <4.0%, Si: 0.05 - 6.0% , Mn 9.0-30.0% and optionally Cr: up to 6.5%, with Cr contents of 0.2-0.3% being given as preferred, Nb and V in contents of up to 0, 06% and Ti and Zr can be present in levels of up to 0.7%. The effect of chromium is considered to stabilize the ε-martensite and to improve the corrosion resistance. For this purpose, higher Cr contents are recommended for Mn contents of 9-18%, while for Mn contents above 18%, lower Cr contents are considered sufficient. At no point the WO 2005/061152 A1 However, it indicates how this ratio should be set in practice.

Eine weitere Möglichkeit höchstfeste Bauteile darzustellen, ist das Warmpresshärten konventioneller Warmumformstähle. Nach dem Press-Hardening - nach vorheriger Vollaustenitisierung - weisen diese Stähle ein martensitisches Gefüge auf, das allerdings ein relativ geringes Restverformungsvermögen besitzt.Another possibility to represent very high-strength components is the hot-pressing hardening of conventional hot-forming steels. After press hardening - after prior full austenitizing - these steels have a martensitic structure, which, however, has a relatively low residual deformation capacity.

Neben dem voranstehend erläuterten Stand der Technik ist aus der EP 0 425 058 A1 eine Verwendung eines beruhigt vergossenen Stahles, der 0,15 - 0,25 % C, 3,40 - 6,10 % Mn, 0 - 1,0 % Ni, 0 - 1,0 % Cr, 0 - 1,0 % Mo, 0 - 0,15 % V, max. 0,03 % P, max. - 0,03 % S, max. - 0,6 % Si, max. 0,05 % Al, Rest Eisen und übliche Verunreinigungen enthält, als Werkstoff zur Herstellung von Rohren zur Verstärkung von Kraftfahrzeugtüren mit der Maßgabe bekannt, dass die folgende Beziehung für die Summe der Legierungsanteile (in Gewichts-%) erfüllt ist: Mn + Ni + Cr + Mo + 10 × V ≧ 4,5 Gewichts − %

Figure imgb0001
In addition to the above-described prior art is from the EP 0 425 058 A1 a use of a mildly cast steel containing 0.15 - 0.25% C, 3.40 - 6.10% Mn, 0 - 1.0% Ni, 0 - 1.0% Cr, 0 - 1.0% Mo, 0 - 0.15% V, max. 0.03% P, max. - 0.03% S, max. - 0.6% Si, max. 0.05% Al, balance iron and common impurities, as a material for the production of pipes for Reinforcement of motor vehicle doors with the proviso that the following relationship for the sum of alloy parts (in% by weight) is fulfilled: Mn + Ni + Cr + Not a word + 10 × V ≧ 4.5 weight - %
Figure imgb0001

Vor dem Hintergrund des voranstehend erläuterten Standes der Technik bestand die Aufgabe der Erfindung darin, ein Stahlflachprodukt mit guter Festigkeit und guter Verformbarkeit aus einem Stahl zu schaffen, der sich kostengünstiger herstellen lässt als die bekannten hochmanganhaltigen Stähle und gleichzeitig hohe Bruchdehnungswerte und damit einhergehend eine deutlich verbesserte Umformbarkeit besitzt. Darüber hinaus sollte ein Verfahren zur Herstellung eines solchen Stahlflachprodukts angegeben werden.Against the background of the prior art described above, the object of the invention was to provide a steel flat product with good strength and good ductility from a steel that can be produced more cost-effectively than the known high manganese steels and at the same time high elongation at break values and, consequently, a significantly improved Formability possesses. In addition, a method for producing such a flat steel product should be specified.

In Bezug auf den Stahl ist diese Aufgabe erfindungsgemäß durch den in Anspruch 1 angegebenen Stahl gelöst worden.With respect to the steel, this object has been achieved according to the invention by the steel specified in claim 1.

Schließlich besteht die Lösung der in Bezug auf das Verfahren oben angegebenen Aufgabe darin, dass zur Herstellung eines Stahlflachprodukts die in Anspruch 17 als notwendig angegebenen Arbeitsschritte absolviert werden, wobei zu diesen Arbeitsschritten die in Anspruch 17 als optional genannten Schritte hinzukommen können.Finally, the solution of the above-stated in relation to the method above task is that for the production of a flat steel product, the steps specified in claim 17 are completed as necessary, which can be added to these steps in claim 17 as optional steps.

Vorteilhafte Ausgestaltungen der Erfindung sind in den abhängigen Ansprüchen angegeben und werden nachfolgend wie der allgemeine Erfindungsgedanke im Einzelnen erläutert.Advantageous embodiments of the invention are specified in the dependent claims and are explained below as the general inventive concept in detail.

Die Erfindung schlägt ein Werkstoffkonzept vor, gemäß dem ein Stahl, der neben Eisen und unvermeidbaren Verunreinigungen aus (in Gew.-%)

  • C: 0,02 - 0,5 %,
  • Mn: 5 - 12,0 %,
  • Si: 0,05 - 1,0 %,
  • Al: bis zu 3,0 %,
  • Cr: 0,1 - 4,0 %,
  • Cu: bis zu 2,0 %,
  • Ni: bis zu 2,0 %,
  • N: bis zu 0,05 %,
  • P: bis zu 0,05 %,
  • S: bis zu 0,01 %
  • besteht und optional ein Element oder mehrere Elemente aus der Gruppe "V, Nb, Ti" enthält,
  • wobei die Summe der Gehalte an diesen Elementen höchstens gleich 0,5 % ist.
The invention proposes a material concept according to which a steel, in addition to iron and unavoidable impurities from (in wt .-%)
  • C: 0.02-0.5%,
  • Mn: 5 - 12.0%,
  • Si: 0.05-1.0%,
  • Al: up to 3.0%,
  • Cr: 0.1 - 4.0%,
  • Cu: up to 2.0%,
  • Ni: up to 2.0%,
  • N: up to 0.05%,
  • P: up to 0.05%,
  • S: up to 0.01%
  • and optionally contains one or more elements from the group "V, Nb, Ti",
  • wherein the sum of the contents of these elements is at most equal to 0.5%.

Das Gefüge eines aus einem solchen erfindungsgemäßen Stahl erzeugten Stahlflachprodukts besteht typischerweise zu 30 - 100 % aus Härtungsgefüge (Martensit, angelassener Martensit oder Bainit), während der Rest des Gefüges austenitisch ist.The microstructure of a steel flat product produced from such a steel according to the invention typically consists of 30-100% of hardening structures (martensite, tempered martensite or bainite), while the remainder of the structure is austenitic.

Im Vergleich zu den bekannten hochmanganhaltigen Stählen lässt sich ein erfindungsgemäßer Stahl aufgrund seiner in einem mittleren Gehaltsbereich liegenden Mn-Gehalten zu deutlich verminderten Legierungs- und Erzeugungskosten sowohl bei der Erzeugung über Strangguss als auch bei der Erzeugung über ein Bandgussverfahren herstellen. Kohlenstoff bestimmt bei einem erfindungsgemäßen Stahl zum einen die Festigkeit von Martensit und zum anderen die Menge und die Stabilität des Restaustenits. Bei zu hohen Kohlenstoffgehalten wird die Schweißbarkeit und Zähigkeit des Stahls, z. B. durch Bildung von Cr-Karbiden, negativ beeinflusst. Idealerweise liegt daher der Kohlenstoffgehalt von Mn-Stählen der erfindungsgemäßen Art unter 0,5 Gew.-%, wobei sich optimale Eigenschaften ergeben, wenn der C-Gehalt auf weniger als 0,2 Gew.-%, insbesondere weniger als 0,1 Gew.-%, beschränkt ist. Bei zu geringem Kohlenstoffgehalt wird jedoch die Menge und Stabilität des verbleibenden Restaustenits beeinträchtigt. Deshalb beträgt der C-Gehalt eines erfindungsgemäßen Stahls mindestens 0,02 Gew.-%, insbesondere mindestens 0,03 Gew.-%, beispielsweise mindestens 0,05 Gew.-%.Compared to the known high manganese steels, a steel according to the invention, because of its Mn contents in an average content range, can be produced at significantly reduced alloying and production costs both during continuous casting production and during production via a strip casting process. In the case of a steel according to the invention, carbon firstly determines the strength of martensite and, secondly, the amount and the stability of the retained austenite. At too high carbon contents, the weldability and toughness of the steel, z. B. by formation of Cr carbides, adversely affected. Ideally, therefore, the carbon content of Mn steels of the type according to the invention is below 0.5 wt .-%, with optimum properties arise when the C content to less than 0.2 wt .-%, in particular less than 0.1 wt .-%, is limited. However, if the carbon content is too low, the amount and stability of the remaining retained austenite will be affected. Therefore, the C content of a steel according to the invention is at least 0.02 wt .-%, in particular at least 0.03 wt .-%, for example at least 0.05 wt .-%.

Mangan ist ein Austenitbildner. Es verzögert die Umwandlung von Ferrit, Perlit und Bainit und stabilisiert damit Austenit bis zur Martensitstarttemperatur. Mangan fördert dabei die Ausbildung von kubisch oder hexagonal verzerrtem Martensit (α- oder ε-Martensit). Diese Mangan-Martensite zeichnen sich durch hohe Festigkeiten und einer gegenüber C-induziertem, kubisch verzerrtem α-Martensit wesentlich höheren Zähigkeit aus. Bei zu geringem Mangangehalt entsteht bei der Abkühlung Bainit, was eine niedrigere Festigkeit und Bruchdehnung mit sich bringt. Bei zu hohem Mangangehalt besteht dagegen die Gefahr, dass der gesamte Austenit bis Raumtemperatur stabil bleibt. Der erfindungsgemäß vorgegebene Mangangehalt von 5 - 12 % ermöglicht dagegen die Einstellung einer Martensitmatrix mit einem Restaustenitanteil im Gefüge. Besonders sicher tritt dieser Effekt ein, wenn der Mn-Gehalt mindestens 6 Gew.-% oder sogar mindestens 7 Gew.-% beträgt, wobei eine Optimierung der positiven Einflüsse von Mangan in einem erfindungsgemäßen Stahl dadurch erzielt werden kann, dass die Obergrenze des Mn-Gehalts auf 10 Gew.-%, insbesondere auf weniger 9 Gew.-%, beispielsweise auf bis zu 8,5 Gew.-%, beschränkt wird.Manganese is an austenite former. It retards the transformation of ferrite, pearlite and bainite and thus stabilizes austenite up to the martensite start temperature. Manganese promotes the formation of cubic or hexagonal distorted martensite (α- or ε-martensite). These manganese martensites are characterized by high strengths and a much higher toughness compared to C-induced cubic distorted α-martensite. If the manganese content is too low, bainite is formed on cooling, which results in lower strength and elongation at break. On the other hand, if the manganese content is too high, there is a risk that the entire austenite will remain stable up to room temperature. By contrast, the manganese content of 5-12% prescribed by the invention makes it possible to set a martensite matrix with a Residual austenite content in the microstructure. This effect occurs particularly reliably when the Mn content is at least 6% by weight or even at least 7% by weight, wherein optimization of the positive effects of manganese in a steel according to the invention can be achieved by limiting the upper limit of Mn Content is limited to 10% by weight, in particular less than 9% by weight, for example up to 8.5% by weight.

Aluminium und Silizium sind starke Ferritbildner. Beide Elemente wirken dem Einfluss der Austenitbildner C und Mn entgegen. Die wesentliche Aufgabe der Elemente Si und Al besteht in einem erfindungsgemäßen Stahl darin, die Karbidausscheidung in der Martensitmatrix zu unterdrücken und damit die Stabilität des Restaustenits zu fördern. Gleichzeitig führen Si und Al zu einer Mischkristallhärtung und reduzieren das spezifische Gewicht des Stahls. Bei zu geringem Si- und Al-Gehalt kann die Karbidausscheidung jedoch möglicherweise nicht effektiv unterdrückt werden. Bei zu hohen Gehalten an Si und Al wird dagegen die Verarbeitung sowohl bei einer Erzeugung über ein Strangguss- als auch bei einer Erzeugung über ein Bandgussverfahren erschwert.Aluminum and silicon are strong ferrite formers. Both elements counteract the influence of austenite formers C and Mn. The essential task of the elements Si and Al in a steel according to the invention is to suppress the carbide precipitation in the martensite matrix and thus to promote the stability of the retained austenite. At the same time, Si and Al lead to solid solution hardening and reduce the specific gravity of the steel. However, if the Si and Al content is too low, carbide precipitation may not be effectively suppressed. On the other hand, if the contents of Si and Al are too high, the processing is made more difficult both by production by continuous casting and by production by a strip casting method.

Deshalb sieht die Erfindung vor, den Si-Gehalt auf max. 1 Gew.-% zu beschränken, wobei die positiven Effekte der Anwesenheit von Si dadurch effektiv genutzt werden können, wenn der Si-Gehalt des erfindungsgemäßen Stahls mindestens 0,05 Gew.-%, insbesondere 0,1 Gew.-%, beträgt. Die negativen Einflüsse von Si können dadurch besonders sicher ausgeschlossen werden, dass der Si-Gehalt auf 0,7 Gew.-%, insbesondere 0,5 Gew.-%, beschränkt wird.Therefore, the invention provides, the Si content to max. 1 wt .-%, wherein the positive effects of the presence of Si can be effectively used thereby, if the Si content of the steel according to the invention at least 0.05 wt .-%, in particular 0.1 wt .-%, is. The negative effects of Si can thereby be excluded with particular certainty that the Si content is limited to 0.7% by weight, in particular 0.5% by weight.

Um die vorteilhafte Wirkung von Al sicher nutzen zu können, kann der Al-Gehalt auf mindestens 0,01 Gew.-%, insbesondere 0,02 Gew.-%, festgelegt werden, während negative Einflüsse von Al besonders sicher dann auszuschließen sind, wenn der Al-Gehalt eines erfindungsgemäßen Stahls auf 2 Gew.-%, insbesondere 1 Gew.-%, beschränkt wird.In order to be able to use the advantageous effect of Al safely, the Al content can be set to at least 0.01% by weight, in particular 0.02% by weight, while negative influences of Al can be excluded with particular certainty if the Al content of a steel according to the invention is limited to 2% by weight, in particular 1% by weight.

Durch die Anwesenheit von Kupfer, Chrom und Nickel wird grundsätzlich der Widerstand eines erfindungsgemäßen Stahls gegen verschiedene Korrosionsmechanismen verbessert. Die positive Wirkung von Cu und Ni lässt sich dabei dadurch besonders sicher nutzen, dass diese Elemente mit in Summe mindestens > 0 Gew.-%, insbesondere 0,1 Gew.-%, betragenden Gehalten dem erfindungsgemäßen Stahl zugegeben werden. Dagegen werden negative Auswirkungen der Anwesenheit von Cu und / oder Ni in erfindungsgemäßen Stählen dadurch vermieden, dass der Gehalt an Cu und Ni jeweils max. 1 Gew.-% beträgt bzw. der Gehalt an Cu und Ni in Summe auf maximal 2 Gew.-%, insbesondere 1 Gew.-%, beschränkt ist.The presence of copper, chromium and nickel fundamentally improves the resistance of a steel according to the invention to various corrosion mechanisms. The positive effect of Cu and Ni can thereby be used with particular certainty by adding these elements having a total of at least> 0% by weight, in particular 0.1% by weight, to the steel according to the invention. In contrast, negative effects of the presence of Cu and / or Ni in steels of the invention are avoided by the fact that the content of Cu and Ni each max. 1 wt .-% is or the content of Cu and Ni in total to a maximum of 2 wt .-%, in particular 1 wt .-%, is limited.

Durch die Anwesenheit von Cr wird in einem erfindungsgemäßen Stahl die Gefahr der Entstehung von Spannungsrisskorrosion gezielt vermindert. Zudem trägt Cr zur Festigkeitssteigerung bei. Ab einem Gehalt von 0,1 Gew.-% Cr sind diese positiven Effekte zu beobachten, wobei die positive Wirkung von Cr dann besonders sicher eintritt, wenn der Cr-Gehalt des erfindungsgemäßen Stahls mindestens 0,5 Gew.-%, insbesondere mindestens 1 Gew.-%, beträgt. Der Cr-Gehalt eines erfindungsgemäßen Stahls ist auf max. 4 Gew.-% beschränkt, weil bei höheren Gehalten Cr-Karbide entstehen können, die die Duktilität des Stahls negativ beeinflussen können. Solche negativen Effekte können dadurch besonders sicher ausgeschlossen werden, dass der Cr-Gehalt auf max. 2 Gew.-% beschränkt wird. Optimal wirkt sich die Anwesenheit von Cr in einem erfindungsgemäßen Stahl aus, wenn der Cr-Gehalt 1 - 2 Gew.-% beträgt.The presence of Cr in a steel according to the invention specifically reduces the risk of the formation of stress corrosion cracking. In addition, Cr contributes to the increase in strength. From a content of 0.1 wt .-% Cr these positive effects are observed, the positive effect of Cr then occurs particularly safe when the Cr content of the steel according to the invention at least 0.5 wt .-%, in particular at least 1 Wt .-%, is. The Cr content of a steel according to the invention is limited to max. 4 wt .-% limited, because at higher levels Cr carbides can form, which can adversely affect the ductility of the steel. Such negative effects can be excluded by the fact that the Cr content to max. 2 wt .-% is limited. Optimally, the presence of Cr in a steel according to the invention has an effect if the Cr content is 1 to 2% by weight.

Ti, Nb und V, die in Gehalten von in Summe bis zu 0,5 Gew.-% in einem erfindungsgemäßen Stahl vorhanden sein können, tragen zur Kornfeinung und Festigkeitssteigerung bei. In Summe oberhalb von 0,5 Gew.-% liegende Gehalte an Ti, Nb und V führen zu keiner Steigerung dieses Effekts. Besonders zielsicher und ressourcenschonend lässt sich die festigkeitssteigernde Wirkung von Ti, Nb und V dann nutzen, wenn die Summe der Gehalte an diesen Mikrolegierungselementen bei einem erfindungsgemäßen Stahl auf 0,3 Gew.-%, insbesondere 0,2 Gew.-%, beschränkt ist. Die positive Wirkung der hier genannten Mikrolegierungselemente stellt sich dabei bereits dann ein, wenn die Summe ihrer Gehalte mindestens 0,025 Gew.-% beträgt. Im Falle der Anwesenheit von Ti wird dessen Gehalt vorteilhafterweise auf max. 0,15 Gew.-% beschränkt, um grobe Ti-Ausscheidungen zu verhindern. Durch die Zugabe von Stickstoff in Gehalten von bis zu 0,05 Gew.-%, insbesondere 0,03 Gew.-%, kann das austenitische Gefüge zusätzlich stabilisiert werden. Dieser Effekt tritt bereits dann ein, wenn der N-Gehalt eines erfindungsgemäßen Stahls mindestens 0,002 Gew.-%, insbesondere mindestens 0,0025 Gew.-%, beträgt, wobei sich ein optimaler Einfluss ergibt, wenn der N-Gehalt auf max. 0,025 Gew.-% beschränkt ist.Ti, Nb and V, which may be present in amounts of up to 0.5% by weight in a steel according to the invention, contribute to grain refining and strength enhancement. In total, above 0.5 wt .-% levels of Ti, Nb and V lead to no increase in this effect. The strength-increasing effect of Ti, Nb and V can be used in a particularly accurate and resource-saving manner if the sum of the contents of these micro-alloying elements in a steel according to the invention is limited to 0.3% by weight, in particular 0.2% by weight , The positive effect of the micro-alloying elements mentioned here already sets in when the sum of their contents is at least 0.025% by weight. In the case of the presence of Ti, its content is advantageously reduced to max. 0.15 wt .-% limited to prevent coarse Ti precipitates. The addition of nitrogen in amounts of up to 0.05 wt .-%, in particular 0.03 wt .-%, the austenitic structure can be additionally stabilized. This effect occurs already when the N content of a steel according to the invention is at least 0.002 wt .-%, in particular at least 0.0025 wt .-%, with an optimum effect results when the N content to max. 0.025 wt .-% is limited.

Die P-Gehalte eines erfindungsgemäßen Stahls sind auf maximal 0,05 Gew.-%, bevorzugt 0,03 Gew.-%, beschränkt, um negative Einflüsse dieses Elements sicher auszuschließen.The P contents of a steel according to the invention are limited to a maximum of 0.05% by weight, preferably 0.03% by weight, in order to reliably exclude negative influences of this element.

Aus demselben Grund ist der S-Gehalt eines erfindungsgemäßen Stahls auf max. 0,01 Gew.-%, insbesondere 0,005 Gew.-%, beschränkt.For the same reason, the S content of a steel according to the invention is limited to max. 0.01 wt .-%, in particular 0.005 wt .-%, limited.

Grundsätzlich gilt, dass das erfindungsgemäße Legierungskonzept so abgestimmt ist, dass die Entstehung von Härtungsgefüge mit oder ohne Restaustenit im Warmband ermöglicht wird. Das heißt:
Die Martensitstarttemperatur MS eines im Rahmen der Erfindung legierten Stahls liegt oberhalb und die Martensitfinishtemperatur MF eines erfindungsgemäß zusammengesetzten Stahls liegt unterhalb der Raumtemperatur.In principle, the alloy concept according to the invention is adapted so that the formation of hardened structures with or without retained austenite in the hot strip is made possible. This means:
The martensite start temperature M S of a steel alloyed in the context of the invention is above and the martensite finish temperature M F of a steel assembled according to the invention is below the room temperature.

Das erfindungsgemäße Legierungskonzept ermöglicht die Einstellung eines Härtungsgefüges mit bis zu 70 % Austenit. Je nach Legierungslage können folgende Phasen auftreten:

  • Stabiler Austenit,
  • Metastabiler Austenit mit Fähigkeit zur spannungsinduzierten Martensitbildung (TRIP-Effekt),
  • C- und/oder Mn- verzerrter kubischer α-Martensit,
  • Hexagonal verzerrter ε-Martensit,
  • Bainit.
The alloy concept according to the invention makes it possible to set a hardening structure with up to 70% austenite. Depending on the alloy layer, the following phases may occur:
  • Stable austenite,
  • Metastable austenite capable of stress-induced martensite formation (TRIP effect),
  • C- and / or Mn-distorted cubic α-martensite,
  • Hexagonal distorted ε-martensite,
  • Bainite.

Das erfindungsgemäße Verfahren zur Herstellung eines Stahlflachprodukts, umfasst folgende Arbeitsschritte:

  • Erschmelzen einer erfindungsgemäß zusammengesetzten Stahlschmelze,
  • Erzeugen eines Ausgangsprodukts für ein anschließendes Warmwalzen, indem die Stahlschmelze zu einem Strang, von dem mindestens eine Bramme oder Dünnbramme als Ausgangsprodukt für das Warmwalzen abgeteilt wird, oder über Zwei-Rollen-Bandguss zu einem gegossenen Band vergossen wird, das als Ausgangsprodukt dem Warmwalzen zugeführt wird,
  • Wärmebehandeln des Ausgangsprodukts, um das Ausgangsprodukt auf eine Warmwalzstarttemperatur von 1150 - 1000 °C zu bringen,
  • Warmwalzen des Ausgangsprodukts zu einem Warmband mit einer Dicke von höchstens 2,5 mm, wobei das Warmwalzen bei einer 1050 - 800 °C betragenden Warmwalzendtemperatur beendet wird,
  • Haspeln des Warmbands zu einem Coil bei einer Haspeltemperatur ≤ 700 °C,
  • wobei sich an das Haspeln jeweils optional die folgenden Arbeitsschritte anschließen können:
    • Glühen des Warmbands bei einer 250 - 950 °C betragenden Warmbandglühtemperatur,
    • Kaltwalzen des geglühten Warmbands in einem Schritt oder in mehreren Schritten zu einem Kaltband mit einer Dicke von höchstens 60 % der Dicke des Warmbands,
    • Glühen des Kaltbands bei einer 450 - 950 °C betragenden Kaltbandglühtemperatur,
    • Beschichten der Oberfläche des Warmbands oder des Kaltbands mit einem metallischen Korrosionsschutzüberzug,
    • Beschichten der Oberfläche des Warmbands oder des Kaltbands mit einem organischen Überzug.
The method according to the invention for producing a flat steel product comprises the following steps:
  • Melting a molten steel composite according to the invention,
  • Producing a starting product for subsequent hot rolling by casting the molten steel into a strand from which at least one slab or thin slab is separated as a raw material for hot rolling, or by two-roll strip casting into a cast strip fed as a raw material to hot rolling becomes,
  • Heat treating the starting product to bring the starting product to a hot rolling start temperature of 1150-1000 ° C,
  • Hot rolling the starting product into a hot strip having a thickness of at most 2.5 mm, the hot rolling being terminated at a hot rolling end temperature of 1050-800 ° C,
  • Coiling the hot strip into a coil at a reel temperature ≤ 700 ° C,
  • whereby the following working steps can optionally be added to the reeling:
    • Annealing the hot strip at a hot strip annealing temperature of 250 - 950 ° C,
    • Cold rolling the annealed hot strip in one step or in several steps to one Cold-rolled strip not exceeding 60% of the thickness of the hot-rolled strip,
    • Annealing the cold strip at a cold strip annealing temperature of 450-950 ° C,
    • Coating the surface of the hot strip or cold strip with a metallic anti-corrosion coating;
    • Coating the surface of the hot strip or cold strip with an organic coating.

Die Möglichkeiten der Erzeugung von Warm- oder Kaltbändern, die aus erfindungsgemäßem Mn-Stahl bestehen, sind in dem beigefügten Diagramm zusammengefasst. Im Einzelnen umfassen sie folgende Bearbeitungsschritte:The possibilities of producing hot or cold strips, which consist of inventive Mn steel, are summarized in the attached diagram. In detail, they include the following processing steps:

WarmbanderzeugungHot strip production

Gegenüber Hoch-Mn-Stählen ist die Vergießbarkeit erfindungsgemäßer Mn-Stähle in Folge der Absenkung des Mn-Gehaltes verbessert.Compared with high Mn steels, the castability of Mn steels according to the invention is improved as a result of the reduction in the Mn content.

Eine erste Möglichkeit der Warmbanderzeugung besteht im konventionellen Strangguss. Dabei erweist sich ein erfindungsgemäßer Stahl als besonders vorteilhaft, weil er eine geringere Warmbanddicke von weniger als < 2,5 mm erlaubt. Dies ist darin begründet, dass sein Umformwiderstand in Folge der Absenkung des Mn-Gehaltes gegenüber konventionellen hochmanganghaltigen Stählen deutlich reduziert ist.A first possibility of warm strip production consists of conventional continuous casting. In this case, an inventive steel proves to be particularly advantageous because it allows a lower hot strip thickness of less than <2.5 mm. This is due to the fact that its deformation resistance is significantly reduced as a result of lowering the Mn content compared to conventional high-manganese steel.

Es ist ebenfalls möglich, Mn-Stähle durch Bandgießen herzustellen. Beim Bandgießen sind Warmbanddicken von weniger als 2,0 mm realisierbar.It is also possible to make Mn steels by strip casting. In strip casting, hot strip thicknesses of less than 2.0 mm can be achieved.

Warmbandglühunghot strip annealing

Durch die Glühung des Warmbandes werden die höheren Austenitanteile eingestellt. Danach verringert sich die Festigkeit, und die Bruchdehnung nimmt deutlich zu. Nach der Warmbandglühung wird bis zu 70 % Austenit je nach Analysenkonzept eingestellt, der für die Verbesserung der Bruchdehnung hauptverantwortlich ist. Da eine Martensitmatrix im ungeglühten Warmband vorliegt, ist es schwierig, es direkt zu Kaltband zu prozessieren. Somit kann eine Warmbandglühung auch dem Zweck dienen, das Warmband für das Kaltwalzen zu entfestigen. Für die Warmbandglühung kommt sowohl eine Haubenglühung als auch eine Durchlaufglühung in Frage.The annealing of the hot strip sets the higher austenite content. Thereafter, the strength decreases, and the elongation at break increases significantly. After hot strip annealing, up to 70% austenite is adjusted according to the analysis concept, which is mainly responsible for improving the elongation at break. Since a martensite matrix is present in the unannealed hot strip, it is difficult to process it directly to cold strip. Thus, hot strip annealing may also serve the purpose of debonding the hot strip for cold rolling. For the hot strip annealing both a bell annealing and a continuous annealing comes into question.

Kaltwalzen und GlühenCold rolling and annealing

Durch Kaltwalzen des geglühten oder des ungeglühten Warmbandes (dann mit optimierter Haspeltemperatur) wird die Banddicke weiter reduziert und die Bandplanheit verbessert. Die nachfolgende Glühung beseitigt die Kaltverfestigung für die Bauteilherstellung und führt zur optimalen Gefügeeinstellung mit erhöhtem Austenitanteil.Cold rolling the annealed or unannealed hot strip (then with optimized coiler temperature) further reduces strip thickness and improves strip flatness. The subsequent annealing removes the strain hardening for the component production and leads to the optimal microstructure setting with increased austenite content.

Oberflächenveredelungsurface finishing

Sowohl das geglühte Warmband als auch das geglühte Kaltband können entweder elektrolytisch oder durch Feuerverzinkung (im Anschluss an die Kaltbandglühung) oder durch sonstige Bandbeschichtung veredelt werden. Es ist ebenfalls möglich, das jeweils erhaltene Stahlband mit einer organischen Beschichtung zu versehen.Both the annealed hot strip and the annealed cold strip can be either electrolytic or through Hot dip galvanizing (following the cold strip annealing) or be refined by other coil coating. It is also possible to provide the respective steel strip obtained with an organic coating.

Warmformungthermoforming

Das angestrebte Gefüge eines erfindungsgemäßen Stahls mit typischerweise 30 - 100 % Härtungsgefüge (Martensit, angelassener Martensit oder Bainit) und als Rest Austenit kann dadurch erreicht werden, dass der Stahl warmgeformt und abgeschreckt wird.The desired structure of a steel according to the invention with typically 30-100% hardening structure (martensite, tempered martensite or bainite) and the remainder austenite can be achieved by thermoforming and quenching the steel.

Auf Grundlage der erfindungsgemäßen Stähle ist es demnach möglich, durch Warmumformung mit anschließender Härtung höchstfeste Bauteile zu erzeugen, deren Restverformungsvermögen aufgrund der Bildung harter, aber vergleichsweise zäher Phasen gegenüber konventionellen hochfesten Stählen signifikant verbessert ist.On the basis of the steels according to the invention, it is therefore possible to produce high-strength components by hot forming with subsequent hardening, the residual deformation capacity of which is significantly improved due to the formation of hard, but comparatively tough phases compared to conventional high-strength steels.

Ausführungsbeispieleembodiments Beispiel 1example 1

Eine Stahlschmelze, die neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,1 % C, 10 % Mn, 0,4 % Si, 0,008 % N, 1,6 % Al und 2 % Cr enthielt, ist im Strangguss vergossen und bei einer Warmwalzendtemperatur ET von 900°C zu einem Warmband warmgewalzt worden, das anschließend bei einer Haspeltemperatur HT von 650 °C gehaspelt worden ist. Das so erhaltene Warmband wies eine Zugfestigkeit Rm von 1400 MPa und eine Bruchdehnung A80 von 7 % auf. Der Restaustenit-Anteil seines Gefüges betrug 14 %.A molten steel containing, in addition to iron and unavoidable impurities (in% by weight) 0.1% C, 10% Mn, 0.4% Si, 0.008% N, 1.6% Al and 2% Cr is in continuous casting potted and hot rolled at a hot rolling end temperature ET of 900 ° C to a hot strip, which has been then reeled at a reel temperature HT of 650 ° C. The hot strip thus obtained had a tensile strength Rm of 1400 MPa and an elongation at break A80 of 7%. The residual austenite content of his structure was 14%.

Beispiel 2Example 2

Eine Stahlschmelze, die neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,1 % C, 10 % Mn, 0,4 % Si, 0,008 % N, 1,6 % Al und 1,6 % Cr enthielt, ist in einer Bandgießmaschine zu einem gegossenen Band vergossen und bei einer Warmwalzendtemperatur ET von 900 °C zu einem Warmband warmgewalzt worden, welches anschließend bei einer Haspeltemperatur HT von 650 °C gehaspelt worden ist. Anschließend ist eine Haubenglühung durchgeführt worden. Das so erhaltene Band wies eine Zugfestigkeit Rm von 990 MPa und eine Bruchdehnung A50 von 27,5 % auf. Der Restaustenit des erhaltenen Warmbands betrug nach dem Glühen 60 %.A molten steel containing 0.1% C, 10% Mn, 0.4% Si, 0.008% N, 1.6% Al and 1.6% Cr besides iron and unavoidable impurities (in wt%) cast in a strip casting machine to a cast strip and hot rolled at a hot rolling end temperature ET of 900 ° C to a hot strip, which has been then reeled at a reel temperature HT of 650 ° C. Subsequently, a bell annealing has been carried out. The tape thus obtained had a tensile strength Rm of 990 MPa and an elongation at break A50 of 27.5%. The residual austenite of the obtained hot strip was 60% after annealing.

Beispiel 3Example 3

Ein Warmband, das neben Eisen und unvermeidbaren Verunreinigungen aus (in Gew.-%) 0,1 % C, 7 % Mn, 0,13 % Si, 0,02 % Al, 1,5 % Cr, 0,18 % Ni, 0,13 % Cu, 0,02 % N und 0,079 % V bestand, ist einer Haubenglühung bei einer Glühtemperatur von 650°C über eine Glühzeit von 40 h unterzogen worden. Das geglühte Warmband wies eine Zugfestigkeit Rm von 1030 MPa und eine Bruchdehnung A50 von 23 % auf. Der Austenit-Anteil seines Gefüges betrug 30 %.A hot strip which, in addition to iron and unavoidable impurities, consists of (in% by weight) 0.1% C, 7% Mn, 0.13% Si, 0.02% Al, 1.5% Cr, 0.18% Ni , 0.13% Cu, 0.02% N and 0.079% V, was subjected to bell annealing at an annealing temperature of 650 ° C over an annealing time of 40 hours. The annealed hot strip had a tensile strength Rm of 1030 MPa and an elongation at break A50 of 23%. The austenite content of his fabric was 30%.

Beispiel 4Example 4

Ein Warmband, das neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,1 % C, 7 % Mn, 0,13 % Si, 0,02 % Al, 0,6 % Cr, 0,18 % Ni, 0,13 % Cu, 0,02 % N und 0,079 % V enthielt, ist mit einer Gesamtverformung von 50 % kaltgewalzt und anschließend bei einer 680 °C betragenden Glühtemperatur im Durchlauf geglüht worden. Die Zugfestigkeit Rm des erhaltenen Kaltbands betrug 1120 MPa bei einer Bruchdehnung A50 von 21 %. Der Austenit-Anteil des Gefüges betrug 30 %.A hot strip containing, in addition to iron and unavoidable impurities (in% by weight) 0.1% C, 7% Mn, 0.13% Si, 0.02% Al, 0.6% Cr, 0.18% Ni, 0.13% Cu, 0.02% N, and 0.079% V was cold rolled to a total deformation of 50% and then annealed at 680 ° C annealing temperature. The tensile strength Rm of the obtained cold-rolled strip was 1120 MPa at an elongation at break A50 of 21%. The austenite content of the microstructure was 30%.

Beispiel 5Example 5

Eine Stahlschmelze, die neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,11 % C, 5 % Mn, 0,39 % Si, 0,008 % N und 1,5 % Al sowie 0,6 % Cr enthielt, ist im Strangguss vergossen und bei einer Warmwalzendtemperatur ET von 900 °C zu einem Warmband warmgewalzt worden, das anschließend bei einer Haspeltemperatur HT von 650 °C gehaspelt worden ist. Das so erhaltene Warmband wies eine Zugfestigkeit Rm von 1345 MPa und eine Bruchdehnung A80 von 5 % auf. Der Restaustenit-Anteil seines Gefüges betrug 5,5 %.A molten steel containing, in addition to iron and unavoidable impurities (in% by weight) 0.11% C, 5% Mn, 0.39% Si, 0.008% N and 1.5% Al and 0.6% Cr potted in continuous casting and hot rolled at a hot rolling end temperature ET of 900 ° C to a hot strip, which has been then reeled at a reel temperature HT of 650 ° C. The hot strip thus obtained had a tensile strength Rm of 1345 MPa and an elongation at break A80 of 5%. The residual austenite content of his structure was 5.5%.

Beispiel 6Example 6

Das gemäß Beispiel 5 erhaltene Warmband ist über eine Glühzeit von 10 min. einer Warmbandglühung bei 300 °C unterzogen worden. Das geglühte Warmband wies eine Zugfestigkeit Rm von 1100 MPa bei einer Bruchdehnung A80 von 8 % auf.The hot strip obtained according to Example 5 is over an annealing time of 10 min. subjected to a hot strip annealing at 300 ° C. The annealed hot strip had a tensile strength Rm of 1100 MPa at an elongation at break A80 of 8%.

Beispiel 7Example 7

Ein entsprechend Beispiel 2 zusammengesetztes Warmband ist über eine Glühzeit von 10 min. einer Warmbandglühung bei 300 °C unterzogen worden. Das geglühte Warmband wies eine Zugfestigkeit Rm von 1300 MPa bei einer Bruchdehnung A80 von 8 % auf.A composite according to Example 2 hot strip is over a glow time of 10 min. subjected to a hot strip annealing at 300 ° C. The annealed hot strip had a tensile strength Rm of 1300 MPa at an elongation at break A80 of 8%.

Beispiel 8Example 8

Aus einer Stahlschmelze, die neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,12 % C, 7 % Mn, 0,11 % Si, 1,6 % Al, 0,3 % Ni, 0,1 % Cu, 0,007 % N und 0,01 % V und 0,5 % Cr enthielt, ist zu einem gegossenen Band vergossen worden. Das gegossene Band wies eine Zugfestigkeit Rm von 1380 MPa bei einer Bruchdehnung A50 von 6 % auf. Der Anteil des Restaustenits am Gefüge des erhaltenen gegossenen Bands betrug 2 %. Nach einer Haubenglühung betrug seine Zugfestigkeit Rm 1050 MPa und seine Bruchdehnung A50 22 %. Der Anteil des Restaustenits am Gefüge des Bands betrug nach dem Glühen 35 %.From a molten steel, in addition to iron and unavoidable impurities (in wt .-%) 0.12% C, 7% Mn, 0.11% Si, 1.6% Al, 0.3% Ni, 0.1% Cu 0.007% N and 0.01% V and 0.5% Cr was cast into a cast strip. The cast strip had a tensile strength Rm of 1380 MPa at an elongation at break A50 of 6%. The content of residual austenite in the structure of the obtained cast strip was 2%. After annealing, its tensile strength Rm was 1050 MPa and its elongation at break A50 was 22%. The proportion of residual austenite in the structure of the strip after annealing was 35%.

Beispiel 9Example 9

Ein Warmband, das neben Eisen und unvermeidbaren Verunreinigungen aus (in Gew.-%) 0,1 % C, 7 % Mn, 0,20 % Si, 0,01 % N und 2,6 % Cr bestand, ist über drei Minuten einer Glühung bei 920 °C unterzogen, anschließend innerhalb von 7 s in ein Abschreckbecken überführt und dort in Wasser abgeschreckt worden. Alternativ wäre auch mit demselben Ergebnis eine Abschreckung in Öl möglich gewesen. Nach dem Abschrecken betrug seine Zugfestigkeit Rm 1450 MPa bei einer Bruchdehnung A80 von 11 %. Das Produkt RmxA80 betrug demnach ca. 16.000 MPa x %. Das Gefüge des auf diese Weise erhaltenen Warmbands bestand aus kubisch verzerrtem α-Martensit und geringen Volumenanteilen von jeweils ca. 5 % an Austenit und hexagonal verzerrtem ε-Martensitanteilen.A hot strip consisting of (in wt%) 0.1% C, 7% Mn, 0.20% Si, 0.01% N and 2.6% Cr besides iron and unavoidable impurities is over three minutes subjected to annealing at 920 ° C, then transferred within 7 s in a quenching tank and quenched there in water. Alternatively, deterrence in oil would have been possible with the same result. After quenching, its tensile strength Rm was 1450 MPa with an elongation at break A80 of 11%. The product RmxA80 was therefore about 16,000 MPa x%. The fabric of this way obtained hot strip consisted of cubic distorted α-martensite and low volume fractions of about 5% each of austenite and hexagonal distorted ε martensite.

Beispiel 10Example 10

Ein Warmband, das neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,1 % C, 7 % Mn, 0,13 % Si, 0,02 % Al, 1,5 % Cr, 0,18 % Ni, 0,13 % Cu, 0,002 % N und 0,08 % V enthielt, ist zu einem Kaltband kaltgewalzt und anschließend feuerverzinkt worden. Das verzinkte Kaltband wies eine Zugfestigkeit Rm von 1300 MPa bei einer Bruchdehnung A50 von 15 % auf. Der Anteil des Restaustenits am Gefüge des erhaltenen gegossenen Bands betrug 20 %.A hot strip containing, in addition to iron and unavoidable impurities (in% by weight) 0.1% C, 7% Mn, 0.13% Si, 0.02% Al, 1.5% Cr, 0.18% Ni, 0.13% Cu, 0.002% N and 0.08% V was cold rolled into a cold strip and then hot dip galvanized. The galvanized cold strip had a tensile strength Rm of 1300 MPa at an elongation at break A50 of 15%. The content of retained austenite in the structure of the obtained cast strip was 20%.

Beispiel 11Example 11

Ein Warmband, das neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,08 % C, 8 % Mn, 0,15 % Si, 0,02 % Al, 1 % Cr, 0,2 % Ni, 0,15 % Cu, 0,015 % N und 0,06 % V enthielt, ist zu einem Kaltband kaltgewalzt und anschließend einer Haubenglühung bei einer Glühtemperatur von 550 °C unterzogen worden. Nach der Haubenglühung betrug seine Zugfestigkeit Rm 1080 MPa und seine Bruchdehnung A50 25 %. Der Anteil des Restaustenits am Gefüge des gegossenen Bands lag nach dem Glühen bei 30 %.A hot strip containing, in addition to iron and unavoidable impurities (in% by weight) 0.08% C, 8% Mn, 0.15% Si, 0.02% Al, 1% Cr, 0.2% Ni, 0, 15% Cu, 0.015% N and 0.06% V was cold rolled into a cold strip and then subjected to bell annealing at an annealing temperature of 550 ° C. After annealing, its tensile strength Rm was 1080 MPa and its elongation at break A50 was 25%. The proportion of retained austenite in the structure of the cast strip after annealing was 30%.

Beispiel 12Example 12

Ein Stahlblech, das neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,05 % C, 0,06 % Si, 1,1 % Cr, 0,01 % N und 10 % Mn enthielt, ist innerhalb von drei Minuten auf 920 °C erwärmt worden. Anschließend ist das Blech innerhalb von 7 s in jeweils ein Abschreckbecken transferiert worden, in dem es in Öl- oder Wasser abgeschreckt worden ist. Der in Öl abgeschreckte Stahl wies eine Zugfestigkeit Rm von 1390 MPa bei einer Bruchdehnung A80 von 12 % auf. Das Produkt Rm*A betrug dementsprechend 16680 MPa%. Der in Wasser abgeschreckte Stahl wies eine Zugfestigkeit Rm von 1350 MPa bei einer Bruchdehnung A80 von 12 % auf. Das Produkt Rm*A betrug für den wasserabgeschreckten Stahl dementsprechend 16200 MPa%. Nach der Öl- oder Wasserabschreckung bestand die Mikrostruktur des Stahls aus kubisch verzerrtem α-Martensit und geringen Volumengehalten aus zähem Austenit (ca. 4 %) sowie hexagonal verzerrten ε-Martensit (ca. 6 %).A steel sheet containing, in addition to iron and unavoidable impurities (in% by weight), 0.05% C, 0.06% Si, 1.1% Cr, 0.01% N and 10% Mn is within three Heated to 920 ° C minutes. Subsequently, the sheet has been transferred within 7 s in each case a quenching tank in which it has been quenched in oil or water. The oil quenched steel had a tensile strength Rm of 1390 MPa at a breaking elongation A80 of 12%. Accordingly, the product Rm * A was 16,680 MPa%. The quenched steel in water had a tensile strength Rm of 1350 MPa at a breaking elongation A80 of 12%. The product Rm * A was accordingly 16200 MPa% for the water quenched steel. After oil or water quenching, the microstructure of the steel consisted of cubically distorted α-martensite and low volume contents of tough austenite (about 4%) and hexagonal distorted ε-martensite (about 6%).

Beispiel 13Example 13

Ein Stahlblech, das neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,05 % C, 10 % Mn, 0,06 % Si, 0,009 % N, 1,1 % Cr und 1 % Ni enthielt, ist innerhalb von drei Minuten auf 920 °C erwärmt worden. Anschließend ist das Blech innerhalb von 7 s in jeweils ein Abschreckbecken transferiert worden, in dem es in Öl- oder Wasser abgeschreckt worden ist. Der in Öl abgeschreckte Stahl wies eine Zugfestigkeit Rm von 1315 MPa bei einer Bruchdehnung A80 von 12,1 % auf. Das Produkt Rm*A betrug dementsprechend 15910 MPa%. Der in Wasser abgeschreckte Stahl wies eine Zugfestigkeit Rm von 1285 MPa bei einer Bruchdehnung A80 von 12,3 %. Für den wasserabgeschreckten Stahl betrug das Produkt Rm*A demnach 15810 MPa%. Nach Öl- oder Wasserabschreckung bestand die Mikrostruktur des Stahls aus kubisch verzerrtem α-Martensit und geringen Volumengehalten aus zähem Austenit (ca. 7 %) sowie hexagonal verzerrten ε-Martensit (ca. 5 %).A steel sheet containing, in addition to iron and unavoidable impurities (in% by weight), 0.05% C, 10% Mn, 0.06% Si, 0.009% N, 1.1% Cr and 1% Ni is within heated to 920 ° C for three minutes. Subsequently, the sheet has been transferred within 7 s in each case a quenching tank in which it has been quenched in oil or water. The oil quenched steel had a tensile strength Rm of 1315 MPa at an elongation at break A80 of 12.1%. The product Rm * A was accordingly 15910 MPa%. The water-quenched steel had a tensile strength Rm of 1285 MPa at a breaking elongation A80 of 12.3%. For the water-quenched steel, the product Rm * A was therefore 15810 MPa%. After oil or water quenching, the microstructure of the steel was cubic distorted α-martensite and low Volume contents of tough austenite (about 7%) and hexagonal distorted ε-martensite (about 5%).

Beispiel 14Example 14

Ein Stahlblech, das neben Eisen und unvermeidbaren Verunreinigungen (in Gew.-%) 0,1 % C, 10 % Mn, 0,06 % Si, 0,009 % N, 1,1 % Cr und 1,5 % Al enthielt, ist innerhalb von drei Minuten auf 920 °C erwärmt worden. Anschließend ist das Blech innerhalb von 7 s in jeweils ein Abschreckbecken transferiert worden, in dem es in Öl- oder Wasser abgeschreckt worden ist. Der in Öl abgeschreckte Stahl wies eine Zugfestigkeit Rm von 1350 MPa bei einer Bruchdehnung A80 von 10,8 % auf. Das Produkt Rm*A betrug dementsprechend 14580 MPa%. Der in Wasser abgeschreckte Stahl wies eine Zugfestigkeit Rm von 1350 MPa bei einer Bruchdehnung A80 von 10,6 %. Für den wasserabgeschreckten Stahl betrug das Produkt Rm*A demnach 14310 MPa%. Nach der Öl- oder Wasserabschreckung bestand die Mikrostruktur des Stahls aus kubisch verzerrtem α-Martensit und geringen Volumengehalten aus zähem Austenit (ca. 12 %).A steel sheet containing, in addition to iron and unavoidable impurities (in% by weight), 0.1% C, 10% Mn, 0.06% Si, 0.009% N, 1.1% Cr and 1.5% Al heated to 920 ° C within three minutes. Subsequently, the sheet has been transferred within 7 s in each case a quenching tank in which it has been quenched in oil or water. The oil quenched steel had a tensile strength Rm of 1350 MPa at an elongation at break A80 of 10.8%. Accordingly, the product Rm * A was 14580 MPa%. The water-quenched steel had a tensile strength Rm of 1350 MPa at an elongation at break A80 of 10.6%. For the water-quenched steel, the product Rm * A was 14310 MPa%. After oil or water quenching, the microstructure of the steel consisted of cubically distorted α-martensite and low volume contents of tough austenite (about 12%).

Insgesamt wird durch die erfindungsgemäße Vorgehensweise eine gegenüber dem Stand der Technik für warmumgeformte höchstfeste Materialien verbesserte Kombination aus Bauteilfestigkeit und Restverformungsvermögen erzielt, welche durch hohe Werte des Produkts aus Zugfestigkeit und jeweiliger Bruchdehnung charakterisiert ist.Overall, the procedure according to the invention achieves an improved combination of component strength and residual deformation capacity, which is characterized by high values of the product of tensile strength and respective elongation at break compared to the state of the art for hot-formed highest-strength materials.

Claims (17)

  1. Flat steel product having a thickness of a maximum of 2.5 mm and an elongation at break A80 which is at least 4% and a tensile strength Rm which is from 900 to 1500 MPa and which in addition to iron and inevitable impurities comprises (in % by weight)
    C: 0.02 - 0.5%,
    Mn: 5 - 12.0%,
    Si: 0.05 - 1.0%,
    Al: up to 3.0%,
    Cr: 0.1 - 4.0%,
    Cu: up to 2.0%,
    Ni: up to 2.0%,
    N: up to 0.05%,
    P: up to 0.05%,
    S: up to 0.01%
    and optionally one or more elements from the group "V, Nb, Ti", wherein the sum of the contents of these elements is at a maximum equal to 0.5%,
    wherein the structure of the steel consists of 30 to 100% of hardening structure (martensite, tempered martensite or bainite), whilst the remainder of the structure is austenitic.
  2. Flat steel product according to claim 1, characterised in that the C content thereof is at least 0.03% by weight.
  3. Flat steel product according to any one of the preceding claims, characterised in that the Mn content thereof is a maximum of 10% by weight.
  4. Flat steel product according to any one of the preceding claims, characterised in that the Mn content thereof is less than 9.5% by weight.
  5. Flat steel product according to any one of the preceding claims, characterised in that the Si content thereof is a maximum of 0.5% by weight.
  6. Flat steel product according to any one of the preceding claims, characterised in that the Al content thereof is a maximum of 2% by weight.
  7. Flat steel product according to any one of the preceding claims, characterised in that the Cr content thereof is at least 0.5% by weight.
  8. Flat steel product according to any one of the preceding claims, characterised in that the Cr content thereof is at least 1% by weight.
  9. Flat steel product according to any one of the preceding claims, characterised in that the Cr content thereof is a maximum of 3% by weight.
  10. Flat steel product according to any one of the preceding claims, characterised in that the Cr content thereof is a maximum of 2% by weight.
  11. Flat steel product according to any one of the preceding claims, characterised in that the Cu content thereof is a maximum of 1% by weight.
  12. Flat steel product according to any one of the preceding claims, characterised in that the Ni content thereof is a maximum of 1% by weight.
  13. Flat steel product according to any one of the preceding claims, characterised in that the N content thereof is at least 0.0025% by weight.
  14. Flat steel product according to any one of the preceding claims, characterised in that the N content thereof is a maximum of 0.03% by weight.
  15. Flat steel product according to any one of the preceding claims, characterised in that the sum of the contents of the optionally present elements from the group "V, Nb, Ti" is at a maximum equal to 0.3% by weight.
  16. Flat steel product according to any one of the preceding claims, characterised in that the optionally present content of Ti is at a maximum equal to 0.15% by weight.
  17. Method for producing a flat steel product constituted according to any one of claims 1 to 16, comprising the following operating steps:
    - melting a steel melt which in addition to iron and inevitable impurities comprises (in % by weight)
    C: 0.02 - 0.5%,
    Mn: 5 - 12.0%,
    Si: 0.05 - 1.0%,
    Al: up to 3.0%,
    Cr: 0.1 - 4.0%,
    Cu: up to 2.0%,
    Ni: up to 2.0%,
    N: up to 0.05%,
    P: up to 0.05%,
    S: up to 0.01%
    and optionally one or more elements from the group "V, Nb, Ti", wherein the sum of the contents of these elements is at a maximum equal to 0.5%,
    - producing a starting product for a subsequent hot rolling operation by the steel melt being cast to form a billet, from which at least one slab or thin slab is divided off as a starting product for the hot rolling or to form a cast strip, which is supplied as a starting product to the hot rolling operation,
    - heat treating the starting product in order to bring the starting product to a hot rolling starting temperature of 1150 to 1000°C,
    - hot rolling the starting product to form a hot strip having a thickness of a maximum of 2.5 mm, wherein the hot rolling is terminated at a hot rolling end temperature of 1050 to 800°C,
    - reeling the hot strip to form a coil at a reeling temperature of ≤ 700°C,
    - wherein the following operating steps may optionally follow the reeling:
    - annealing the hot strip at a hot strip annealing temperature of 250 to 950°C,
    - cold-rolling the annealed hot strip in one step or in several steps to form a cold strip having a thickness of a maximum of 60% of the thickness of the hot strip,
    - annealing the cold strip at a cold strip annealing temperature which is from 450 to 950°C,
    - coating the surface of the hot strip or the cold strip with a metal corrosion protection coating,
    - coating the surface of the hot strip or the cold strip with an organic coating.
EP11164339.1A 2010-04-30 2011-04-29 High tensile steel containing Mn, steel surface product made from such steel and method for producing same Active EP2383353B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102010019114 2010-04-30

Publications (3)

Publication Number Publication Date
EP2383353A2 EP2383353A2 (en) 2011-11-02
EP2383353A3 EP2383353A3 (en) 2015-03-18
EP2383353B1 true EP2383353B1 (en) 2019-11-06

Family

ID=44520636

Family Applications (1)

Application Number Title Priority Date Filing Date
EP11164339.1A Active EP2383353B1 (en) 2010-04-30 2011-04-29 High tensile steel containing Mn, steel surface product made from such steel and method for producing same

Country Status (1)

Country Link
EP (1) EP2383353B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102020204356A1 (en) 2020-04-03 2021-10-07 Thyssenkrupp Steel Europe Ag Hardened sheet metal component, produced by hot forming a flat steel product and process for its production

Families Citing this family (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2455222T5 (en) † 2010-07-02 2018-03-05 Thyssenkrupp Steel Europe Ag Superior strength steel, cold formable and flat steel product composed of such a steel
WO2015001367A1 (en) 2013-07-04 2015-01-08 Arcelormittal Investigación Y Desarrollo Sl Cold rolled steel sheet, method of manufacturing and vehicle
DE102013012118A1 (en) * 2013-07-18 2015-01-22 C.D. Wälzholz GmbH Cold-rolled narrow strip in the form of flat wire or profiles made of a high-strength steel for use in flexible pipes, in particular in flexible pipes for offshore applications and method for producing such cold-rolled narrow strips
DE102015111866A1 (en) * 2015-07-22 2017-01-26 Salzgitter Flachstahl Gmbh Formable lightweight structural steel with improved mechanical properties and process for the production of semi-finished products from this steel
DE102015112889A1 (en) * 2015-08-05 2017-02-09 Salzgitter Flachstahl Gmbh High-strength manganese-containing steel, use of the steel for flexibly rolled flat steel products and production methods together with flat steel product for this purpose
DE102015112886A1 (en) * 2015-08-05 2017-02-09 Salzgitter Flachstahl Gmbh High-strength aluminum-containing manganese steel, a process for producing a steel flat product from this steel and steel flat product produced therefrom
DE102016110661A1 (en) 2016-06-09 2017-12-14 Salzgitter Flachstahl Gmbh Process for producing a cold-rolled steel strip from a high-strength, manganese-containing steel
CN109642263B (en) * 2016-08-23 2021-02-26 德国沙士基达板材有限公司 Method for producing a high-strength steel strip with improved properties during further processing, and such a steel strip
CN106297960B (en) * 2016-08-23 2017-07-14 重庆市特僖通信器材有限公司 A kind of cable production technology of Copper-Aluminum compound band
DE102016115618A1 (en) 2016-08-23 2018-03-01 Salzgitter Flachstahl Gmbh Process for producing a high-strength steel strip with improved properties during further processing and such a steel strip
EP3504351B1 (en) * 2016-08-24 2023-10-11 The University of Hong Kong Dual-phase steel and method for the fabrication of the same
DE102016117502A1 (en) 2016-09-16 2018-03-22 Salzgitter Flachstahl Gmbh A method of making a hot or cold strip and / or a flexible rolled flat steel product from a high strength manganese steel and flat steel product hereafter
DE102016117494A1 (en) 2016-09-16 2018-03-22 Salzgitter Flachstahl Gmbh Process for producing a formed component from a medium manganese steel flat product and such a component
DE102016117508B4 (en) 2016-09-16 2019-10-10 Salzgitter Flachstahl Gmbh Process for producing a flat steel product from a medium manganese steel and such a flat steel product
RU2725939C1 (en) 2016-09-16 2020-07-07 Зальцгиттер Флахшталь Гмбх Method of making part subjected to re-moulding from flat steel product with manganese content and part of such type
WO2018083028A1 (en) * 2016-11-02 2018-05-11 Salzgitter Flachstahl Gmbh Seamless tube of a medium manganese steel and method for the production thereof
RU2728054C1 (en) 2016-11-02 2020-07-28 Зальцгиттер Флахшталь Гмбх Steel product with medium content of manganese for use at low temperatures and method of production thereof
US20180251871A1 (en) * 2017-03-01 2018-09-06 Ak Steel Properties, Inc. Hot-rolled steel with very high strength and method for production
CN106893931A (en) * 2017-03-04 2017-06-27 蒋培丽 A kind of granule enhancement type austenitic steel and its steel plate manufacturing process
US20210087662A1 (en) 2017-07-25 2021-03-25 Thyssenkrupp Steel Europe Ag Metal Sheet Component, Manufactured by Hot Forming a Flat Steel Product and Method for Its Manufacture
WO2019122960A1 (en) * 2017-12-19 2019-06-27 Arcelormittal Cold rolled and heat treated steel sheet, method of production thereof and use of such steel to produce vehicle parts
DE102017223633A1 (en) 2017-12-21 2019-06-27 Voestalpine Stahl Gmbh Cold-rolled flat steel product with metallic anticorrosion layer and method for producing the same
JP7329304B2 (en) * 2018-03-13 2023-08-18 クリーブランド－クリフス スティール プロパティーズ、インク． Reduction at Elevated Temperature of Coated Steels Containing Metastable Austenite
CN109097680B (en) * 2018-08-10 2020-07-28 宝武集团鄂城钢铁有限公司 Method for manufacturing high-manganese high-aluminum nonmagnetic steel plate smelted by 50t intermediate frequency induction furnace
CN110306117B (en) * 2019-08-02 2021-04-02 宝武集团鄂城钢铁有限公司 High-uniformity steel plate for super-thick structure and manufacturing method thereof
CN110951956B (en) * 2019-12-19 2021-07-27 中北大学 Production method of ultra-high plasticity TWIP steel
US20230340650A1 (en) * 2020-10-02 2023-10-26 The University Of Hong Kong Strong and Ductile Medium Manganese Steel and Method of Making
CN114150227B (en) * 2021-12-07 2022-11-18 武汉科技大学 High-toughness hot stamping steel rolled by medium and thin slabs with Rm more than or equal to 1500MPa and production method
CN115572887B (en) * 2022-10-31 2023-06-09 常州大学 Manganese steel in superfine twin crystal gradient structure and preparation method thereof

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07188834A (en) 1993-12-27 1995-07-25 Nkk Corp High strength steel sheet having high ductility and its production
JPH11209823A (en) 1998-01-23 1999-08-03 Kobe Steel Ltd Manufacture of high strength steel sheet excellent in press formability
US20080247902A1 (en) 2005-06-28 2008-10-09 Piotr R. Scheller High-Strength, Lightweight Austenitic-Martensitic Steel and the Use Thereof
WO2009021897A1 (en) 2007-08-15 2009-02-19 Thyssenkrupp Steel Ag Dual-phase steel, flat product made of such dual-phase steel and method for producing a flat product
WO2009075494A1 (en) 2007-12-06 2009-06-18 Posco High carbon steel sheet superior in tensile strength and elongation and method for manufacturing the same
WO2009142362A1 (en) 2008-05-20 2009-11-26 Posco High strength steel sheet and hot dip galvanized steel sheet having high ductility and excellent delayed fracture resistance and method for manufacturing the same

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4796946A (en) * 1987-09-04 1989-01-10 Inland Steel Company Automotive vehicle door and bar reinforcement
DE3935965C1 (en) * 1989-10-26 1991-05-08 Mannesmann Ag, 4000 Duesseldorf, De
US5454883A (en) * 1993-02-02 1995-10-03 Nippon Steel Corporation High toughness low yield ratio, high fatigue strength steel plate and process of producing same
JP4608739B2 (en) * 2000-06-14 2011-01-12 Ｊｆｅスチール株式会社 Manufacturing method of steel pipe for automobile door reinforcement
US7806165B2 (en) 2003-12-23 2010-10-05 Salzgitter Flachstahl Gmbh Method for making hot strips of lightweight construction steel

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07188834A (en) 1993-12-27 1995-07-25 Nkk Corp High strength steel sheet having high ductility and its production
JPH11209823A (en) 1998-01-23 1999-08-03 Kobe Steel Ltd Manufacture of high strength steel sheet excellent in press formability
US20080247902A1 (en) 2005-06-28 2008-10-09 Piotr R. Scheller High-Strength, Lightweight Austenitic-Martensitic Steel and the Use Thereof
WO2009021897A1 (en) 2007-08-15 2009-02-19 Thyssenkrupp Steel Ag Dual-phase steel, flat product made of such dual-phase steel and method for producing a flat product
WO2009075494A1 (en) 2007-12-06 2009-06-18 Posco High carbon steel sheet superior in tensile strength and elongation and method for manufacturing the same
WO2009142362A1 (en) 2008-05-20 2009-11-26 Posco High strength steel sheet and hot dip galvanized steel sheet having high ductility and excellent delayed fracture resistance and method for manufacturing the same

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
ALBERNY R.: "Laminage à chaud des produits plats sur train à bandes. Partie 1", TECHNIQUES DE L'INGÉNIEUR, 10 March 2007 (2007-03-10), pages 1 - 16, XP055750851
FABREGUE PASCAL: "Métallurgie du laminage à chaud", TECHNIQUES DE L'INGÉNIEUR, 10 September 2000 (2000-09-10), pages 1 - 16, XP055750859
HOFMANN H., HELLER T., SIKORA S.: "(Design of) Modern steels for Automotive application", MATERIALS SCIENCE FORUM, vol. 638-642, 12 January 2010 (2010-01-12), pages 3111 - 3116, XP055750844
MATEJA JIM: "Car's panels are only skin deep", CHICAGO TRIBUNE, 6 October 2002 (2002-10-06), pages 1 - 3, XP055750862

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102020204356A1 (en) 2020-04-03 2021-10-07 Thyssenkrupp Steel Europe Ag Hardened sheet metal component, produced by hot forming a flat steel product and process for its production

Also Published As

Publication number Publication date
EP2383353A2 (en) 2011-11-02
EP2383353A3 (en) 2015-03-18

Similar Documents

Publication Publication Date Title
EP2383353B1 (en) High tensile steel containing Mn, steel surface product made from such steel and method for producing same
EP2809819B1 (en) Ultrahigh-strength multiphase steel having improved properties during production and processing
EP3332047B1 (en) Production method of a flexibly-rolled steel sheet product and its use
EP2855717B1 (en) Steel sheet and method to manufacture it
DE602004010699T2 (en) Cold rolled steel sheet having a tensile strength of 780 MPa or more, excellent local moldability and suppressed weld hardness increase
DE60133493T2 (en) Hot-dip galvanized steel sheet and process for its production
EP2439290B1 (en) Multiphase steel, cold rolled flat product produced from this multiphase steel and method for producing same
DE102008035714A1 (en) Hot stamping steel sheet having low-temperature tempering property, methods of producing the same, methods of producing parts using the same, and parts made therewith
EP3332046B1 (en) High-tensile manganese steel containing aluminium, method for producing a sheet-steel product from said steel and sheet-steel product produced according to this method
EP3535431B1 (en) Steel product with an intermediate manganese content for low temperature application and production method thereof
WO2001009396A1 (en) High resistance steel band or sheet and method for the production thereof
EP3504349B1 (en) Method for producing a high-strength steel strip with improved properties for further processing, and a steel strip of this type
WO2012045613A1 (en) Multi-phase steel, cold-rolled flat product produced from a multi-phase steel of this type, and method for producing it
WO2012110165A1 (en) Hot rolled flat steel product produced from a complex phase steel, and method for producing same
WO2015117934A1 (en) High-strength flat steel product having a bainitic-martensitic microstructure and method for producing such a flat steel product
EP2690184A1 (en) Produit plat en acier laminé à froid et son procédé de fabrication
EP3512968B1 (en) Method for producing a flat steel product made of a manganese-containing steel, and such a flat steel product
EP3551776A1 (en) Method for producing a hot or cold strip and/or a flexibly rolled flat steel product made of a high-strength manganese steel and flat steel product produced by said method
WO2017211952A1 (en) Method for producing a cold-rolled steel strip having trip-characteristics made of a high-strength mangan-containing steel
DE102016115618A1 (en) Process for producing a high-strength steel strip with improved properties during further processing and such a steel strip
EP3964591A1 (en) Hot-rolled steel sheet product and method for producing a hot-rolled steel sheet product
WO2023025635A1 (en) Cold-rolled flat steel product and method for the production thereof

Legal Events

Date Code Title Description
AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

RIC1 Information provided on ipc code assigned before grant

Ipc: C21D 8/02 20060101AFI20150212BHEP

Ipc: C21D 8/04 20060101ALI20150212BHEP

Ipc: C22C 38/18 20060101ALI20150212BHEP

Ipc: C22C 38/04 20060101ALI20150212BHEP

17P Request for examination filed

Effective date: 20150918

RBV Designated contracting states (corrected)

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

17Q First examination report despatched

Effective date: 20170203

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20190517

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

Ref country code: AT

Ref legal event code: REF

Ref document number: 1198793

Country of ref document: AT

Kind code of ref document: T

Effective date: 20191115

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 502011016222

Country of ref document: DE

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

Free format text: LANGUAGE OF EP DOCUMENT: GERMAN

REG Reference to a national code

Ref country code: SE

Ref legal event code: TRGR

REG Reference to a national code

Ref country code: NL

Ref legal event code: FP

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG4D

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: BG

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200206

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200207

Ref country code: LT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: PL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200306

Ref country code: NO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200206

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: RS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: HR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: IS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200306

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

REG Reference to a national code

Ref country code: DE

Ref legal event code: R026

Ref document number: 502011016222

Country of ref document: DE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: RO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: CZ

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

PLAX Notice of opposition and request to file observation + time limit sent

Free format text: ORIGINAL CODE: EPIDOSNOBS2

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: SM

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

26 Opposition filed

Opponent name: ARCELORMITTAL

Effective date: 20200730

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: MC

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PLBB Reply of patent proprietor to notice(s) of opposition received

Free format text: ORIGINAL CODE: EPIDOSNOBS3

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20200430

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20200430

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20200429

REG Reference to a national code

Ref country code: BE

Ref legal event code: MM

Effective date: 20200430

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20200430

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20200429

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20200429

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20200429

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: TR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: MT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

APAH Appeal reference modified

Free format text: ORIGINAL CODE: EPIDOSCREFNO

APBM Appeal reference recorded

Free format text: ORIGINAL CODE: EPIDOSNREFNO

APBP Date of receipt of notice of appeal recorded

Free format text: ORIGINAL CODE: EPIDOSNNOA2O

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20191106

APAY Date of receipt of notice of appeal deleted

Free format text: ORIGINAL CODE: EPIDOSDNOA2O

APBM Appeal reference recorded

Free format text: ORIGINAL CODE: EPIDOSNREFNO

APBP Date of receipt of notice of appeal recorded

Free format text: ORIGINAL CODE: EPIDOSNNOA2O

APBQ Date of receipt of statement of grounds of appeal recorded

Free format text: ORIGINAL CODE: EPIDOSNNOA3O

APBQ Date of receipt of statement of grounds of appeal recorded

Free format text: ORIGINAL CODE: EPIDOSNNOA3O

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 20230419

Year of fee payment: 13

P01 Opt-out of the competence of the unified patent court (upc) registered

Effective date: 20230526

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20230426

Year of fee payment: 13

Ref country code: FR

Payment date: 20230420

Year of fee payment: 13

Ref country code: DE

Payment date: 20220620

Year of fee payment: 13

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20230420

Year of fee payment: 13

Ref country code: AT

Payment date: 20230420

Year of fee payment: 13

APBU Appeal procedure closed

Free format text: ORIGINAL CODE: EPIDOSNNOA9O