EP2690184B1 - Produit plat en acier laminé à froid et son procédé de fabrication - Google Patents

Produit plat en acier laminé à froid et son procédé de fabrication Download PDF

Info

Publication number
EP2690184B1
EP2690184B1 EP12178332.8A EP12178332A EP2690184B1 EP 2690184 B1 EP2690184 B1 EP 2690184B1 EP 12178332 A EP12178332 A EP 12178332A EP 2690184 B1 EP2690184 B1 EP 2690184B1
Authority
EP
European Patent Office
Prior art keywords
temperature
weight
cold
strip
content
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
EP12178332.8A
Other languages
German (de)
French (fr)
Other versions
EP2690184A1 (en
Inventor
Brigitte Dr. Hammer
Thomas Dr. Heller
Frank Dr. Hisker
Rudolf Prof.Dr.-Ing. Kawalla
Grzegorz Korpala
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
Application filed by ThyssenKrupp Steel Europe AG filed Critical ThyssenKrupp Steel Europe AG
Priority to EP12178332.8A priority Critical patent/EP2690184B1/en
Priority to US14/417,659 priority patent/US20150218684A1/en
Priority to PCT/EP2013/065838 priority patent/WO2014016421A1/en
Priority to JP2015523569A priority patent/JP6202579B2/en
Priority to CN201380048837.7A priority patent/CN104641008B/en
Publication of EP2690184A1 publication Critical patent/EP2690184A1/en
Application granted granted Critical
Publication of EP2690184B1 publication Critical patent/EP2690184B1/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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • C21D8/0226—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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

Definitions

  • the invention relates to a cold-rolled flat steel product with a tensile strength Rm of at least 1400 MPa and an elongation A80 of at least 5%. Products of this type are characterized by very high strength in combination with good elongation properties and as such are particularly suitable for the production of components for motor vehicle bodies.
  • the invention also relates to a method for producing a flat steel product according to the invention.
  • flat steel product is understood here to mean steel sheets or steel strips produced by a rolling process, as well as blanks and the like separated therefrom.
  • alloy contents are only given here in “%”, this always means “% by weight”, unless expressly stated otherwise.
  • a process for the production of a flat steel product that has tensile strengths of significantly more than Should have 1000 MPa.
  • a steel melt containing (in% by weight) 0.0005-1% C, 0.5-10% Cu, up to 2% Mn, up to 5% Si, up to 0.5 % Ti, up to 0.5% Nb, up to 5% Ni, up to 2% Al and the remainder iron and unavoidable impurities due to manufacturing.
  • the melt is poured into a strip, the thickness of which is max. 10 mm and which is quickly cooled to a temperature of at most 1000 ° C by sprinkling with water or a water-air mixture.
  • the cast strip is then hot rolled at a usual reduction rate.
  • the hot rolling is ended at a final temperature at which all of the copper is still in solid solution in the ferrite and / or austenite matrix.
  • the tape is then subjected to a rapid cooling step to keep the copper in supersaturated solid solution in the ferrite and / or austenite solution.
  • the hot strip obtained in this way can be rolled into a cold strip with a degree of cold rolling of 40-80%.
  • This cold strip is then subjected to a recrystallizing annealing, in which it is brought as quickly as possible to an annealing temperature in the range of 840 ° C. and held there in order to dissolve as much of the copper contained in the steel as possible.
  • Another method for producing an extremely strong cold strip is from the US 7,591,977 B2 known. According to this process, a hot strip containing (in% by weight) 0.1-0.25% C, 1.0-2.0% Si and 1.5-3.0% Mn with a cold rolling degree of 30-70 % rolled into a cold strip, which is then subjected to a continuous heat treatment.
  • a first annealing step the cold strip is heated to a first annealing temperature above its Ar3 temperature in order to dissolve the carbides present in the cold strip. This is followed by cooling to a second annealing temperature, starting from the first annealing temperature and at a cooling rate of at least 10 ° C./s.
  • This second annealing step which is carried out to form bainite, is carried out until the structure of the cold strip consists of at least 60% bainite and at least 5% residual austenite and the remainder of polygonal ferrite.
  • the aim is that the structure is as completely bainitic as possible and that other structural components are only present in traces.
  • the cold strip produced in this way achieves tensile strengths of up to 1180 MPa with an elongation of at least 9% and, if necessary, can be covered with a metallic layer that protects against corrosion.
  • a high-strength cold-rolled steel sheet is known, which is made from a steel with (in% by weight) 0.17-0.73% C, up to 3% Si, 0.5-3.0% Mn, up to 0.1% P, up to 0.07% S, up to 3.0% Al, up to to 0.010% N and in each case optional contents of Cr of 0.05-5,%, 0.005-1.0% V, 0.005-0.5% Mo, 0.01-0.1% Ti, 0.01-0 , 1% Nb, 0.0003-0.0050% B, 0.05-2.0% Ni, 0.05-2.0% Cu, 0.001-0.005% Ca and 0.001-0.005% REM, remainder iron and unavoidable impurities, the sum of the Al and Si contents should be at least 0.7%.
  • the sheet metal assembled in this way has a structure which (in area%) consists of 10-90% lower bainite and martensite and a total martensite content of up to 75% and 5-50% residual austenite.
  • the cold-rolled sheet undergoes a heat treatment after cold rolling, in which it is initially annealed for 15 - 600 s at an annealing temperature above its Ac3 temperature and then at a cooling rate of at least 5 ° C / s to 350 - 490 ° C amounting first holding temperature is cooled, at which it is held for 15 - 1000 s. The sheet is then cooled to a second holding temperature of 200-350 ° C in order to be held there for a period of 15-1000 s.
  • the object of the invention was to create a cold-rolled flat steel product that can be produced in a simple and reliable manner and has an optimized combination of further increased strength and good deformability.
  • a method for producing such a cold-rolled flat steel product should be mentioned.
  • the solution according to the invention to the above-mentioned object consists in that at least the work steps specified in claim 9 are carried out to produce a cold-rolled flat steel product according to the invention.
  • the cold-rolled flat steel product according to the invention is characterized in that it has (in% by weight) C: 0.27-0.60%, Si: 0.4-2.5%, Mn: 0.4-3.0 %, Cr: 0.3 - 2% and optionally made of Al: up to 3.0%, Ni: up to 1.0%, Cu: up to 2.0%, Mo: up to 0.4%, Co: up to 1.5%, Ti: up to 0.2%, Nb: up to 0.2%, V: up to 0.5%, and the remainder consists of iron and unavoidable impurities.
  • the structure of the flat steel product according to the invention in the cold-rolled state consists of at least 20% by volume of bainite, 10-35% by volume of retained austenite and the remainder of martensite, whereby it goes without saying that in the structure of the flat steel product, technically unavoidable traces of others Structural components can be present.
  • a cold-rolled flat steel product according to the invention of this type regularly achieves tensile strengths Rm of at least 1400 MPa and an elongation A80 of at least 5%.
  • the C content of the retained austenite is typically more than 1.0% by weight.
  • a steel strip according to the invention has a three-phase structure, the dominant component of which is bainite and which also consists of retained austenite and the remainder of martenisite.
  • the bainite content is at least 60% by volume and the residual austenite content in the range of 10-25% by volume, with the rest of the structure also being filled with martensite.
  • the optimal martensite content is at least 10% by volume.
  • a structure composed in this way produces the best combination of Rm * A80 with the required tensile strength.
  • the retained austenite is predominantly film-like with small globular islands of blocky retained austenite with a grain size ⁇ 5 ⁇ m , so that the retained austenite has high stability and, as a result, a low tendency to undesired transformation into martensite and enables the TRIP effect .
  • Cold strip produced according to the invention regularly reaches tensile strengths Rm of more than 1400 MPa, with elongations A80 which are also regularly above 5%.
  • the quality Rm * A80 of flat steel products according to the invention is regularly above 7000 MPa *%, with qualities Rm * A80 of at least 13500 MPa *% typically being achieved.
  • a cold strip according to the invention has an optimal combination of extreme strength and sufficient formability.
  • the martensite start temperature ie the temperature from which martensite is formed in the steel processed according to the invention, can according to the method described in the article Thermodynamic Exatrapolation and Martensite-Start-Temperature of Substitutionally Alloyed Steels "by H. Bhadeshia, published in Metal Science 15 (1981), pages 178-180 explained procedure.
  • the C content of the flat steel product according to the invention has been set to at least 0.27% by weight.
  • the C content is at least 0.28% by weight.
  • the effects achieved by the comparably high carbon content can be used particularly reliably if the C content is in the range of 0.27-0.4% by weight or 0.28-0.4% by weight.
  • the strength-increasing effect of copper can also be used in a cold-rolled flat steel product according to the invention.
  • a minimum content of 0.15 wt.% Cu, in particular at least 0.2 wt.% Cu can be present in the flat steel product according to the invention.
  • Cu makes a particularly effective contribution to strength when it is present in the flat steel product according to the invention in contents of at least 0.55% by weight, with the negative effects of the presence of Cu being limited by reducing the Cu content to at most 1.5 Wt .-% is limited.
  • Cr lowers the martensite start temperature and suppresses the tendency of the bainite to transform into pearlite or cementite. Furthermore, Cr promotes ferritic conversion in contents up to the upper limit of a maximum of 2 wt. % is limited. In order to effectively utilize the positive influence of Cr, at least 0.3% by weight of Cr is present in the flat steel product according to the invention.
  • Ti, V or Nb can support the creation of a finer-grain structure and promote the bainitic transformation.
  • these micro-alloy elements contribute to the increase in hardness through the formation of precipitates.
  • the positive effects of Ti, V and Nb in the cold-rolled flat steel product according to the invention can be used particularly effectively if their content is in the range of 0.002-0.15% by weight, in particular does not exceed 0.1% by weight.
  • Si is present in a flat steel product according to the invention in contents of 0.4-2.5% by weight and causes a significant solid solution strengthening.
  • the Si content can be set to at least 1.0% by weight. It can also be used for To avoid negative influences, it is advisable to limit the Si content to a maximum of 2% by weight.
  • Al can partially replace the Si content in the steel processed according to the invention.
  • Al like Si, has a deoxidizing effect in steel production.
  • a minimum content of 0.01% by weight Al can be provided.
  • Higher contents of Al prove to be expedient, for example, when the hardness or tensile strength of the steel is to be adjusted to a lower value in favor of improved deformability by adding Al.
  • Si and Al Another function of Si and Al is to suppress the formation of carbide in the bainite and thus to stabilize the retained austenite through dissolved C.
  • the positive influences of the simultaneous presence of Al and Si can be used particularly effectively if the Si and Al contents meet the following condition within the limits specified according to the invention:% Si + 0.8% Al> 1.2% by weight ( with% Si: respective Si content in% by weight,% Al: respective Al content in% by weight).
  • the formation of the structure specified according to the invention can in particular be ensured by the fact that the Mn, Cr, Ni, Cu and C contents of the steel processed according to the invention and accordingly the Mn, Cr, Ni, Cu and C contents of the steel flat product according to the invention meet the following condition 1 ⁇ 0.5% Mn + 0.167% Cr + 0.125% Ni + 0.125% Cu + 1.334% C ⁇ 2, with% Mn the respective Mn content in% by weight, with% Cr the respective Cr content in wt .-%, with% Ni the respective Ni content in wt .-%, with% Cu the respective Cu content in wt .-% and with% C the respective C content in wt .-%.
  • the intermediate product cast from a steel composed according to the invention is first brought to a temperature or kept at a temperature sufficient to end the hot rolling carried out starting from this temperature at a hot rolling end temperature in the range of 830-1000 ° C lie.
  • the hot strip cools down on the roller table following the roll stand in question. After the roller table, the hot strip runs into a coiler, in which it is wound into a coil.
  • the coiling temperature must be at least 560 ° C so that a relatively soft hot strip structure made of ferrite and pearlite is created.
  • An optimal temperature profile for this purpose is obtained when the final hot rolling temperature is in the range from 850 to 950 ° C, in particular in the range from 880 to 950 ° C.
  • the intermediate product is typically heated to a temperature in the range of 1100-1300 ° C. or kept at this temperature before hot rolling.
  • the structure of the hot strip obtained in this way exists mainly made of ferrite and pearlite. The risk of grain boundary oxidation occurring can be minimized by limiting the coiling temperature to a maximum of 750 ° C.
  • the hot strip After coiling, the hot strip is cold-rolled, it being understood that the hot strip can of course be descaled chemically or mechanically in the usual way before cold-rolling.
  • the cold rolling takes place with a degree of cold rolling of at least 30%, in particular at least 45%, in order to accelerate the recrystallization and conversion during the subsequent annealing. In general, maintaining a correspondingly high degree of cold rolling also results in a better surface quality. Cold rolling degrees of at least 50% have proven to be particularly favorable for this.
  • the cold strip obtained according to the invention undergoes an annealing cycle in one continuous run, in which it is heated to a temperature of at least 800 ° C., preferably at least 830 ° C., in a first annealing phase.
  • This first annealing phase lasts at least long enough for the cold strip to be completely austenitized. This typically takes 50 - 150 s.
  • the product is quenched, the cooling rate being at least 8 ° C./s, in particular 10 ° C./s.
  • the target temperature of this quenching is a holding temperature which is 470 ° C or less and higher than that Martensite start temperature MS, from which martensite occurs in the structure of the cold strip.
  • the range of 300-420 ° C, in particular 330-420 ° C can be used as a guide for the range in which the holding temperature should be.
  • the cold strip is held in the holding temperature range in the second annealing phase until the structure of the cold strip has changed to at least 20% by volume in bainite.
  • the holding can be carried out as isothermal holding at the holding temperature reached during cooling or as a slow temperature decrease within the holding temperature range.
  • the flat steel product produced according to the invention can be covered in the usual way with a metallic protective layer. This can be done, for example, by hot dip coating. If an annealing is required before the application of the metallic coating, the heat treatment provided according to the invention can be carried out within the scope of this annealing.
  • a metallic protective layer This can be done, for example, by hot dip coating. If an annealing is required before the application of the metallic coating, the heat treatment provided according to the invention can be carried out within the scope of this annealing.
  • the invention is explained in more detail below on the basis of exemplary embodiments.
  • the correspondingly composed steel melts are cast in a conventional manner to form a strand from which slabs have been separated.
  • the thin slabs were then reheated to a reheating temperature in an equally conventional manner.
  • the heated slabs were hot-rolled into hot strips with a thickness of 2 mm in a likewise conventional hot-rolling stage.
  • the final hot rolling temperature was in the range of 830-900 ° C. Starting from this temperature, the hot strips were cooled to a coiling temperature above 560 ° C. and then reeled into coils.
  • the hot strips obtained in this way have been descaled after coiling and, after descaling, have been cold-rolled to cold strip at cold rolling degrees of 50%.
  • a large number of samples of these cold strips were then subjected to a heat treatment in which they were heated in a first annealing step at a heating rate of at least 1.9 ° C / s to a first annealing temperature in the range of 830 - 850 ° C lay.
  • the cold strips were held at this temperature for a period of 120 seconds until they were completely heated.
  • the holding temperatures T2 were one first batch of tests at 300 ° C, 310 ° C, 330 ° C, 340 ° C, 375 ° C, 390 ° C and 410 ° C. At the respective holding temperature T2, the cold strip samples were held for an annealing period t2.
  • Fig. 1 the achieved tensile strengths Rm are plotted against the respective annealing temperature T2. It can be seen that the cold strip specimens made from steel S5 only achieve the required minimum tensile strength of 1400 MPa under certain annealing conditions, while the tensile strengths of the cold strip specimens made from the other steels were always safely above the minimum limit of 1400 MPa. The reason for this was determined to be the comparatively low carbon content of steel S5, which is at the lower limit of the content range specified according to the invention.
  • Fig. 2 the tensile strengths of the cold strip samples produced from steel S4 are plotted over the annealing duration t2 of the second annealing stage. It can be seen that the cold strip samples held at a holding temperature of 310 ° C, 330 ° C and 350 ° C, i.e. in the holding temperature range of 310 - 350 ° C, reached the required tensile strength Rm of 1400 MPa regardless of the respective annealing duration t2.
  • Fig. 3 the tensile strengths of the cold strip samples produced from steel S5 are plotted in the same way over the annealing time t2 of the second annealing stage. It can be seen here that the cold strip samples held at a holding temperature of 350 ° C and 390 ° C, i.e. in the holding temperature range of 350 - 390 ° C, met the requirements Achieve tensile strength Rm of 1400 MPa if the annealing time t2 is shorter than 145 s.
  • Fig. 4 the elongation A80 of the cold strip samples produced from steel S4 is plotted over the annealing duration t2 of the second annealing stage.
  • elongation A80 of the cold strip samples produced from steel S5 is plotted over the annealing duration t2 of the second annealing stage.
  • the cold strip samples achieve the required elongation A80 of at least 5% regardless of their respective holding temperature T2 and regardless of the respective annealing duration t2. Accordingly, if a short annealing time and suitably low holding temperatures T2 are maintained, a cold-rolled flat steel product according to the invention can also be produced from steel S5 despite its comparatively low C content, in which a high tensile strength Rm is combined with sufficient elongation A80.
  • FIG. 6 an enlargement of a cross section of a cold strip according to the invention is shown in a detail.
  • retained austenite blocks RA-b are marked by way of example and a point is highlighted by a circle where film-like retained austenite RA-f is present in a lamellar layer.
  • Table 1 steel C Table 1 steel C.

Description

Die Erfindung betrifft ein kaltgewalztes Stahlflachprodukt mit einer Zugfestigkeit Rm von mindestens 1400 MPa und einer Dehnung A80 von mindestens 5 %. Produkte dieser Art zeichnen sich durch eine sehr hohe Festigkeit in Kombination mit guten Dehnungseigenschaften aus und sind als solche insbesondere für die Herstellung von Bauteilen für Kraftfahrzeugkarosserien geeignet.The invention relates to a cold-rolled flat steel product with a tensile strength Rm of at least 1400 MPa and an elongation A80 of at least 5%. Products of this type are characterized by very high strength in combination with good elongation properties and as such are particularly suitable for the production of components for motor vehicle bodies.

Ebenso betrifft die Erfindung ein Verfahren zur Herstellung eines erfindungsgemäßen Stahlflachprodukts. Unter dem Begriff "Stahlflachprodukt" werden hier durch einen Walzprozess erzeugte Stahlbleche oder Stahlbänder sowie davon abgeteilte Platinen und desgleichen verstanden.The invention also relates to a method for producing a flat steel product according to the invention. The term “flat steel product” is understood here to mean steel sheets or steel strips produced by a rolling process, as well as blanks and the like separated therefrom.

Sofern hier Legierungsgehalte lediglich in "%" angegeben sind, ist damit immer "Gew.-%" gemeint, sofern nicht ausdrücklich etwas anderes angegeben ist.If alloy contents are only given here in “%”, this always means “% by weight”, unless expressly stated otherwise.

Aus der EP 1 466 024 B1 ( DE 603 15 129 T2 ) ist ein Verfahren zur Herstellung eines Stahlflachprodukts bekannt, das Zugfestigkeiten von deutlich mehr als 1000 MPa aufweisen soll. Um dies zu erreichen, wird eine Stahlschmelze, die (in Gew.-%) 0,0005 - 1 % C, 0,5 - 10 % Cu, bis zu 2 % Mn, bis zu 5 % Si, bis zu 0,5 % Ti, bis zu 0,5 % Nb, bis zu 5 % Ni, bis zu 2 % Al und als Rest Eisen und herstellungsbedingt unvermeidbare Verunreinigungen aufweist. Die Schmelze wird zu einem Band gegossen, dessen Dicke max. 10 mm beträgt und das durch Besprengen mit Wasser oder einem Wasser-Luft-Gemisch rasch auf eine Temperatur von höchstens 1000 °C abgekühlt wird. Anschließend wird das gegossene Band mit einer üblichen Reduktionsrate warmgewalzt. Das Warmwalzen wird bei einer Endtemperatur beendet, bei der sich das gesamte Kupfer noch in fester Lösung in der Ferrit- und/oder Austenitmatrix befindet. Dann wird das Band einem Schritt einer schnellen Abkühlung unterzogen, um das Kupfer in übersättigter fester Lösung in der Ferrit- und/oder Austenitlösung zu halten. Nach einem Haspeln zu einem Coil kann aus dem so erhaltenen Warmband mit einem 40 - 80 % betragenden Kaltwalzgrad ein Kaltband gewalzt werden. Dieses Kaltband wird dann einer rekristallisierenden Glühung unterzogen, bei der es möglichst schnell auf eine im Bereich von 840 °C liegenden Glühtemperatur gebracht und dort gehalten wird, um einen möglichst großen Anteil des im Stahl enthaltenen Kupfers in Lösung zu bringen. Anschließend erfolgt eine schnelle Abkühlung auf eine 400 - 700 °C betragende Temperatur, bei der sich erneut Cu-Ausscheidungen bilden. Auf diese Weise soll durch Ausscheidungshärtung das angestrebte Festigkeitsniveau des Stahls erreicht werden. Gleichzeitig soll der Kupfergehalt die Korrosions- und Versprödungsbeständigkeit des Stahls durch Bildung einer Schutzoxidschicht erhöhen.From the EP 1 466 024 B1 ( DE 603 15 129 T2 ) a process for the production of a flat steel product is known that has tensile strengths of significantly more than Should have 1000 MPa. To achieve this, a steel melt containing (in% by weight) 0.0005-1% C, 0.5-10% Cu, up to 2% Mn, up to 5% Si, up to 0.5 % Ti, up to 0.5% Nb, up to 5% Ni, up to 2% Al and the remainder iron and unavoidable impurities due to manufacturing. The melt is poured into a strip, the thickness of which is max. 10 mm and which is quickly cooled to a temperature of at most 1000 ° C by sprinkling with water or a water-air mixture. The cast strip is then hot rolled at a usual reduction rate. The hot rolling is ended at a final temperature at which all of the copper is still in solid solution in the ferrite and / or austenite matrix. The tape is then subjected to a rapid cooling step to keep the copper in supersaturated solid solution in the ferrite and / or austenite solution. After being reeled into a coil, the hot strip obtained in this way can be rolled into a cold strip with a degree of cold rolling of 40-80%. This cold strip is then subjected to a recrystallizing annealing, in which it is brought as quickly as possible to an annealing temperature in the range of 840 ° C. and held there in order to dissolve as much of the copper contained in the steel as possible. This is followed by rapid cooling to a temperature of 400-700 ° C, at which copper precipitates form again. In this way, the desired level of strength of the steel is to be achieved through precipitation hardening. At the same time, the copper content should increase the steel's resistance to corrosion and embrittlement by forming a protective oxide layer.

Ein weiteres Verfahren zur Herstellung eines extrem festen Kaltbands ist aus der US 7,591,977 B2 bekannt. Gemäß diesem Verfahren wird ein (in Gew.-%) 0,1 - 0,25 % C, 1,0 - 2,0 % Si und 1,5 - 3,0 % Mn enthaltendes Warmband mit einem Kaltwalzgrad von 30 - 70 % zu einem Kaltband gewalzt, das dann einer im kontinuierlichen Durchlauf absolvierten Wärmebehandlung unterzogen wird. Dabei wird das Kaltband in einem ersten Glühschritt auf eine oberhalb seiner Ar3-Temperatur liegende erste Glühtemperatur erwärmt, um im Kaltband vorhandene Karbide in Lösung zu bringen. Anschließend erfolgt eine von der ersten Glühtemperatur ausgehende, mit einer Abkühlgeschwindigkeit von mindestens 10 °C/s erfolgende Abkühlung auf eine zweite Glühtemperatur. Diese ist so gewählt, dass sich im Kaltband Bainit bildet, und liegt typischerweise im Bereich von 300 - 450 °C. Dieser zur Bainitbildung durchgeführte zweite Glühschritt wird so lange ausgeführt, bis das Gefüge des Kaltbands zu mindestens 60 % aus Bainit und zu mindestens 5 % aus Restaustenit sowie als Rest aus polygonalem Ferrit besteht. Dabei wird angestrebt, dass das Gefüge möglichst vollständig bainitisch ist und andere Gefügebestandteile allenfalls in Spuren vorliegen. Das so beschaffene Kaltband erreicht Zugfestigkeiten von bis zu 1180 MPa bei einer Dehnung von mindestens 9 % und kann erforderlichenfalls mit einer metallischen, vor Korrosion schützenden Schicht belegt werden.Another method for producing an extremely strong cold strip is from the US 7,591,977 B2 known. According to this process, a hot strip containing (in% by weight) 0.1-0.25% C, 1.0-2.0% Si and 1.5-3.0% Mn with a cold rolling degree of 30-70 % rolled into a cold strip, which is then subjected to a continuous heat treatment. In a first annealing step, the cold strip is heated to a first annealing temperature above its Ar3 temperature in order to dissolve the carbides present in the cold strip. This is followed by cooling to a second annealing temperature, starting from the first annealing temperature and at a cooling rate of at least 10 ° C./s. This is chosen so that bainite is formed in the cold strip and is typically in the range of 300 - 450 ° C. This second annealing step, which is carried out to form bainite, is carried out until the structure of the cold strip consists of at least 60% bainite and at least 5% residual austenite and the remainder of polygonal ferrite. The aim is that the structure is as completely bainitic as possible and that other structural components are only present in traces. The cold strip produced in this way achieves tensile strengths of up to 1180 MPa with an elongation of at least 9% and, if necessary, can be covered with a metallic layer that protects against corrosion.

Schließlich ist aus der EP 2 327 810 A1 ein hochfestes kaltgewalztes Stahlblech bekannt, das aus einem Stahl mit (in Gew.-%) 0,17 - 0,73 % C, bis zu 3 % Si, 0,5 - 3,0 % Mn, bis zu 0,1 % P, bis zu 0,07 % S, bis zu 3,0 % Al, bis zu 0,010 % N und jeweils optionalen Gehalten an Cr von 0,05 - 5, %, 0,005 - 1,0 % V, 0,005 - 0,5 % Mo, 0,01 - 0,1 % Ti, 0,01 - 0,1 % Nb, 0,0003 - 0,0050 % B, 0,05 - 2,0 % Ni, 0,05 - 2,0 % Cu, 0,001 - 0,005 % Ca und 0,001 - 0,005 % REM, Rest Eisen und unvermeidbaren Verunreinigungen besteht, wobei die Summe der Al- und Si-Gehalte mindestens 0,7 % betragen soll. Das derart zusammengesetzte Blech weist ein Gefüge auf, welches (in Flächen-%) aus 10 - 90 % aus unterem Bainit und Martensit besteht und einen Gesamtgehalt an Martensit von bis zu 75 % sowie aus 5 - 50 % Restaustenit besteht. Um dieses Gefüge zu erhalten, durchläuft das kaltgewalzte Blech nach dem Kaltwalzen eine Wärmebehandlung, bei der es zunächst für 15 - 600 s bei einer oberhalb seiner Ac3-Temperatur liegenden Glühtemperatur geglüht und anschließend mit einer Abkühlgeschwindigkeit von mindestens 5 °C/s auf eine 350 - 490 °C betragende erste Haltetemperatur abgekühlt wird, bei der es über 15 - 1000 s gehalten wird. Anschließend wird das Blech auf eine zweite Haltetemperatur von 200 - 350 °C abgekühlt, um dort über eine Dauer von 15 - 1000 s gehalten zu werden.Finally from the EP 2 327 810 A1 a high-strength cold-rolled steel sheet is known, which is made from a steel with (in% by weight) 0.17-0.73% C, up to 3% Si, 0.5-3.0% Mn, up to 0.1% P, up to 0.07% S, up to 3.0% Al, up to to 0.010% N and in each case optional contents of Cr of 0.05-5,%, 0.005-1.0% V, 0.005-0.5% Mo, 0.01-0.1% Ti, 0.01-0 , 1% Nb, 0.0003-0.0050% B, 0.05-2.0% Ni, 0.05-2.0% Cu, 0.001-0.005% Ca and 0.001-0.005% REM, remainder iron and unavoidable impurities, the sum of the Al and Si contents should be at least 0.7%. The sheet metal assembled in this way has a structure which (in area%) consists of 10-90% lower bainite and martensite and a total martensite content of up to 75% and 5-50% residual austenite. In order to obtain this structure, the cold-rolled sheet undergoes a heat treatment after cold rolling, in which it is initially annealed for 15 - 600 s at an annealing temperature above its Ac3 temperature and then at a cooling rate of at least 5 ° C / s to 350 - 490 ° C amounting first holding temperature is cooled, at which it is held for 15 - 1000 s. The sheet is then cooled to a second holding temperature of 200-350 ° C in order to be held there for a period of 15-1000 s.

Vor dem Hintergrund des voranstehend erläuterten Standes der Technik bestand die Aufgabe der Erfindung darin, ein kaltgewalztes Stahlflachprodukt zu schaffen, dass auf einfache und betriebssichere Weise hergestellt werden kann und eine optimierte Kombination aus weiter gesteigerter Festigkeit und guter Verformbarkeit aufweist. Darüber hinaus sollte ein Verfahren zur Herstellung eines solchen kaltgewalzten Stahlflachprodukts genannt werden.Against the background of the prior art explained above, the object of the invention was to create a cold-rolled flat steel product that can be produced in a simple and reliable manner and has an optimized combination of further increased strength and good deformability. In addition, a method for producing such a cold-rolled flat steel product should be mentioned.

In Bezug auf das kaltgewalzte Stahlflachprodukt ist diese Aufgabe erfindungsgemäß durch das in Anspruch 1 angegebene Stahlflachprodukt gelöst worden.With regard to the cold-rolled flat steel product, this object has been achieved according to the invention by the flat steel product specified in claim 1.

In Bezug auf das Verfahren besteht die erfindungsgemäße Lösung der voranstehend genannten Aufgabe darin, dass zur Herstellung eines erfindungsgemäßen kaltgewalzten Stahlflachprodukts mindestens die in Anspruch 9 angegebenen Arbeitsschritte durchlaufen werden.With regard to the method, the solution according to the invention to the above-mentioned object consists in that at least the work steps specified in claim 9 are carried out to produce a cold-rolled flat steel product according to the invention.

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 in detail below, like the general inventive concept.

Das erfindungsgemäße kaltgewalzte Stahlflachprodukt zeichnet sich dadurch aus, dass es aus (in Gew.-%) C: 0,27 - 0,60 %, Si: 0,4 - 2,5 %, Mn: 0,4 - 3,0 %, Cr: 0,3 - 2 % sowie jeweils optional aus Al: bis zu 3,0 %, Ni: bis zu 1,0 %, Cu: bis zu 2,0 %, Mo: bis zu 0,4 %, Co: bis zu 1,5 %, Ti: bis zu 0,2 %, Nb: bis zu 0,2 %, V: bis zu 0,5 %, und als Rest aus Eisen und unvermeidbaren Verunreinigungen besteht. Dabei besteht das Gefüge des erfindungsgemäßen Stahlflachprodukts im kaltgewalzten Zustand zu mindestens 20 Vol.-% aus Bainit, zu 10 - 35 Vol.-% aus Restaustenit und als Rest aus Martensit, wobei es selbstverständlich ist, dass im Gefüge des Stahlflachprodukts technisch unvermeidbare Spuren anderer Gefügebestandteile vorhanden sein können. Ein so beschaffenes erfindungsgemäßes kaltgewalztes Stahlflachprodukt erzielt regelmäßig Zugfestigkeiten Rm von mindestens 1400 MPa und eine Dehnung A80 von mindestens 5 %. Der C-Gehalt des Restaustenits beträgt typischerweise mehr als 1,0 Gew.-%.The cold-rolled flat steel product according to the invention is characterized in that it has (in% by weight) C: 0.27-0.60%, Si: 0.4-2.5%, Mn: 0.4-3.0 %, Cr: 0.3 - 2% and optionally made of Al: up to 3.0%, Ni: up to 1.0%, Cu: up to 2.0%, Mo: up to 0.4%, Co: up to 1.5%, Ti: up to 0.2%, Nb: up to 0.2%, V: up to 0.5%, and the remainder consists of iron and unavoidable impurities. The structure of the flat steel product according to the invention in the cold-rolled state consists of at least 20% by volume of bainite, 10-35% by volume of retained austenite and the remainder of martensite, whereby it goes without saying that in the structure of the flat steel product, technically unavoidable traces of others Structural components can be present. A cold-rolled flat steel product according to the invention of this type regularly achieves tensile strengths Rm of at least 1400 MPa and an elongation A80 of at least 5%. The C content of the retained austenite is typically more than 1.0% by weight.

Das erfindungsgemäße Verfahren zum Herstellen eines erfindungsgemäß beschaffenen Stahlflachprodukts umfasst folgende Arbeitsschritte:

  • Bereitstellen eines Vorprodukts in Form einer Bramme, Dünnbramme oder eines gegossenen Bands, das aus (in Gew.-%) C: 0,27 - 0,60 %, Si: 0,4 - 2,5 %, Mn: 0,4 - 3,0 %, Cr: 0,3 - 2 % sowie jeweils optional aus Al: bis zu 3,0 %, Ni: bis zu 1,0 %, Cu: bis zu 2,0 %, Mo: bis zu 0,4 %, Co: bis zu 1,5 %, Ti: bis zu 0,2 %, Nb: bis zu 0,2 %, V: bis zu 0,5 % und als Rest aus Eisen und unvermeidbaren Verunreinigungen besteht;
  • Erwärmen des Vorprodukts auf eine im Bereich von 1100 - 1300 °C liegende Temperatur oder Halten des Vorprodukts bei dieser Temperatur;
  • Warmwalzen des Vorprodukts zu einem Warmband in einem oder mehreren Walzstichen, wobei das erhaltene Warmband beim Verlassen des letzten Walzstichs eine Warmwalzendtemperatur von mindestens 830 - 1000 °C aufweist;
  • Haspeln des erhaltenen Warmbands bei einer Haspeltemperatur, die zwischen der Warmwalzendtemperatur und 560 °C liegt;
  • Kaltwalzen des Warmbands zu einem Kaltband mit einem Kaltwalzgrad von mindestens 30 %;
  • Wärmebehandeln des erhaltenen Kaltbands, wobei das Kaltband im Zuge der Wärmebehandlung
    • auf eine mindestens 800 °C betragende Glühtemperatur erwärmt wird, wobei das Kaltband über eine Glühdauer von 50 - 150 s bei der Glühtemperatur gehalten wird,
    • ausgehend von der Glühtemperatur mit einer mindestens 8 °C/s betragenden Abkühlgeschwindigkeit auf eine Haltetemperatur abgekühlt wird, die in einem Haltetemperaturbereich liegt, dessen Obergrenze 470 °C beträgt und dessen Untergrenze höher ist als die Martensitstarttemperatur MS, ab der Martensit im Gefüge des Kaltbands entsteht, und
    • im Haltetemperaturbereich über einen Zeitraum gehalten wird, der ausreicht, um im Gefüge des Kaltbands mindestens 20 Vol.-% Bainit zu bilden.
The method according to the invention for producing a flat steel product according to the invention comprises the following work steps:
  • Providing a preliminary product in the form of a slab, thin slab or a cast strip, which consists of (in% by weight) C: 0.27-0.60%, Si: 0.4-2.5%, Mn: 0.4 - 3.0%, Cr: 0.3 - 2% and optionally made of Al: up to 3.0%, Ni: up to 1.0%, Cu: up to 2.0%, Mo: up to 0 , 4%, Co: up to 1.5%, Ti: up to 0.2%, Nb: up to 0.2%, V: up to 0.5% and the remainder consists of iron and unavoidable impurities;
  • Heating the intermediate product to a temperature in the range of 1100-1300 ° C. or keeping the intermediate product at this temperature;
  • Hot rolling of the preliminary product to form a hot strip in one or more rolling passes, the hot strip obtained having a final hot rolling temperature of at least 830-1000 ° C. when it leaves the last rolling pass;
  • Coiling the obtained hot strip at a coiling temperature which is between the hot rolling end temperature and 560 ° C;
  • Cold rolling the hot strip to form a cold strip with a degree of cold rolling of at least 30%;
  • Heat treatment of the cold strip obtained, wherein the cold strip in the course of the heat treatment
    • is heated to an annealing temperature of at least 800 ° C, with the cold strip being held at the annealing temperature for an annealing period of 50 - 150 s,
    • starting from the annealing temperature with a cooling rate of at least 8 ° C / s, it is cooled to a holding temperature which lies in a holding temperature range, the upper limit of which is 470 ° C and the lower limit of which is higher than the martensite start temperature MS, from which martensite occurs in the structure of the cold strip , and
    • is kept in the holding temperature range for a period of time that is sufficient to form at least 20% by volume of bainite in the structure of the cold strip.

Ein erfindungsgemäßes Stahlband weist ein dreiphasiges Gefüge auf, dessen dominierender Bestandteil Bainit ist und das darüber hinaus aus Restaustenit sowie als Rest aus Martenisit besteht. Optimaler Weise liegt dabei der Bainitanteil bei mindestens 60 Vol.-% und der Restaustenitanteil im Bereich von 10 - 25 Vol.-%, wobei auch hier der Rest des Gefüges jeweils durch Martensit aufgefüllt ist. Der optimale Martensitanteil beträgt mindestens 10 Vol.-%. Ein derart zusammengesetztes Gefüge bewirkt die beste Kombination von Rm*A80 bei der geforderten Zugfestigkeit.A steel strip according to the invention has a three-phase structure, the dominant component of which is bainite and which also consists of retained austenite and the remainder of martenisite. Optimally, the bainite content is at least 60% by volume and the residual austenite content in the range of 10-25% by volume, with the rest of the structure also being filled with martensite. The optimal martensite content is at least 10% by volume. A structure composed in this way produces the best combination of Rm * A80 with the required tensile strength.

Neben den Hauptkomponenten "Bainit", "Restaustenit" und "Martensit" können Gehalte an anderen Gefügebestandteilen vorhanden sein, deren Anteile jedoch zu gering sind, um einen Einfluss auf die Eigenschaften des erfindungsgemäßen Kaltbands zu haben. Der Restaustenit liegt in einem erfindungsgemäßen Kaltband überwiegend filmartig mit kleinen globularen Inseln von blockigem Restaustenit mit einer Korngröße <5 µm vor, so dass der Restaustenit eine hohe Stabilität und damit einhergehend eine geringe Neigung zur unerwünschten Umwandlung in Martensit besitzt sowie den TRIP-Effekt ermöglicht.In addition to the main components "bainite", "retained austenite" and "martensite", contents of other structural constituents may be present, but their proportions are too low to have an influence on the properties of the cold strip according to the invention. In a cold strip according to the invention, the retained austenite is predominantly film-like with small globular islands of blocky retained austenite with a grain size <5 μm , so that the retained austenite has high stability and, as a result, a low tendency to undesired transformation into martensite and enables the TRIP effect .

Erfindungsgemäß erzeugtes Kaltband erreicht regelmäßig Zugfestigkeiten Rm von mehr als 1400 MPa, bei Dehnungen A80, die ebenso regelmäßig oberhalb von 5 % liegen. Dementsprechend liegt die Güte Rm*A80 von erfindungsgemäßen Stahlflachprodukten regelmäßig oberhalb von 7000 MPa*%, wobei typischerweise Güten Rm*A80 von mindestens 13500 MPa*% erreicht werden. Ein erfindungsgemäßes Kaltband verfügt als solches über eine optimale Kombination aus extremer Festigkeit und ausreichender Umformbarkeit.Cold strip produced according to the invention regularly reaches tensile strengths Rm of more than 1400 MPa, with elongations A80 which are also regularly above 5%. Correspondingly, the quality Rm * A80 of flat steel products according to the invention is regularly above 7000 MPa *%, with qualities Rm * A80 of at least 13500 MPa *% typically being achieved. As such, a cold strip according to the invention has an optimal combination of extreme strength and sufficient formability.

Die Martensitstarttemperatur, d. h. die Temperatur, ab der sich in erfindungsgemäß verarbeitetem Stahl Martensit bildet, kann gemäß der im Artikel " Thermodynamic Exatrapolation and Martensite-Start-Temperature of Substitutionally Alloyed Steels" von H. Bhadeshia, erschienen in Metal Science 15 (1981), Seiten 178 -180 erläuterten Vorgehensweise berechnet werden.The martensite start temperature, ie the temperature from which martensite is formed in the steel processed according to the invention, can according to the method described in the article Thermodynamic Exatrapolation and Martensite-Start-Temperature of Substitutionally Alloyed Steels "by H. Bhadeshia, published in Metal Science 15 (1981), pages 178-180 explained procedure.

Kohlenstoff verzögert im erfindungsgemäßen Stahl die Umwandlung in Ferrit/Perlit, senkt die Martensitstarttemperatur MS ab und trägt zur Erhöhung der Härte bei. Um diese positiven Effekte zu nutzen, ist der C-Gehalt des erfindungsgemäßen Stahlflachprodukts auf mindestens 0,27 Gew.-% gesetzt worden. Insbesondere beträgt der C-Gehalt mindestens 0,28 Gew.-%. Die durch den vergleichbar hohen Kohlenstoffgehalt erzielten Effekte lassen sich dann besonders sicher nutzen, wenn der C-Gehalt im Bereich von 0,27 - 0,4 Gew.-% oder 0,28 - 0,4 Gew.-%, liegt.In the steel according to the invention, carbon delays the conversion to ferrite / pearlite, lowers the martensite start temperature MS and contributes to increasing the hardness. In order to use these positive effects, the C content of the flat steel product according to the invention has been set to at least 0.27% by weight. In particular, the C content is at least 0.28% by weight. The effects achieved by the comparably high carbon content can be used particularly reliably if the C content is in the range of 0.27-0.4% by weight or 0.28-0.4% by weight.

Auch in einem erfindungsgemäßen kaltgewalzten Stahlflachprodukt kann die festigkeitssteigernde Wirkung von Kupfer genutzt werden. Hierzu kann im erfindungsgemäßen Stahlflachprodukt ein Mindestgehalt von 0,15 Gew.-% Cu, insbesondere mindestens 0,2 Gew.-% Cu, vorhanden sein. Einen besonders wirksamen Beitrag zur Festigkeit leistet Cu, wenn es in Gehalten von mindestens 0,55 Gew.-% im erfindungsgemäßen Stahlflachprodukt vorhanden ist, wobei sich negative Auswirkungen der Anwesenheit von Cu dadurch begrenzen lassen, dass der Cu-Gehalt auf höchstens 1,5 Gew.-% beschränkt wird.The strength-increasing effect of copper can also be used in a cold-rolled flat steel product according to the invention. For this purpose, a minimum content of 0.15 wt.% Cu, in particular at least 0.2 wt.% Cu, can be present in the flat steel product according to the invention. Cu makes a particularly effective contribution to strength when it is present in the flat steel product according to the invention in contents of at least 0.55% by weight, with the negative effects of the presence of Cu being limited by reducing the Cu content to at most 1.5 Wt .-% is limited.

Mn in Gehalten von mindestens 0,4 Gew.-% und bis zu 3 Gew.-%, insbesondere bis zu 2,5 Gew.-%, fördert im erfindungsgemäß verarbeiteten Stahl die Bainitbildung, wobei die optional zusätzlich vorhandenen Gehalte an Cu, Cr und Ni ebenfalls zur Bildung von Bainit beitragen. Abhängig von den jeweils anderen Bestandteilen des erfindungsgemäß verarbeiteten Stahls kann es dabei zweckmäßig sein, den Mn-Gehalt auf maximal 2 Gew.-% zu beschränken oder den Mindestgehalt an Mn auf 1,5 Gew.-% zu erhöhen.Mn in contents of at least 0.4% by weight and up to 3% by weight, in particular up to 2.5% by weight, promotes the formation of bainite in the steel processed according to the invention, the optionally additionally present contents of Cu, Cr and Ni also contribute to the formation of bainite. Depending on the other constituents of the steel processed according to the invention, it can be useful to increase the Mn content to a maximum of 2% by weight limit or increase the minimum content of Mn to 1.5 wt .-%.

Durch die Zugabe von Cr ist die Martensitstarttemperatur abgesenkt und die Neigung des Bainits zur Umwandlung in Perlit oder Zementit unterdrückt werden. Des Weiteren fördert Cr in Gehalten bis zu der erfindungsgemäß vorgegebenen Obergrenze von maximal 2 Gew.-% die ferritische Umwandlung, wobei sich optimale Wirkungen der Anwesenheit von Cr im erfindungsgemäßen kaltgewalzten Stahlflachprodukt dann ergeben, wenn der Cr-Gehalt auf 1,5 Gew.-% beschränkt ist. Um den positiven Einfluss von Cr wirksam zu nutzen, sind mindestens 0,3 Gew.-% Cr im erfindungsgemäßen Stahlflachprodukt vorhanden.The addition of Cr lowers the martensite start temperature and suppresses the tendency of the bainite to transform into pearlite or cementite. Furthermore, Cr promotes ferritic conversion in contents up to the upper limit of a maximum of 2 wt. % is limited. In order to effectively utilize the positive influence of Cr, at least 0.3% by weight of Cr is present in the flat steel product according to the invention.

Durch die optionale Zugabe von Ti, V oder Nb kann die Entstehung von feinkörnigerem Gefüge unterstützt und die bainitische Umwandlung gefördert werden. Darüber hinaus tragen diese Mikrolegierungselemente durch die Bildung von Ausscheidungen zur Steigerung der Härte bei. Besonders effektiv lassen sich die positiven Wirkungen von Ti, V und Nb im erfindungsgemäßen kaltgewalzten Stahlflachprodukt dann nutzen, wenn ihr Gehalt jeweils im Bereich von 0,002 - 0,15 Gew.-% liegt, insbesondere 0,1 Gew.-% nicht überschreitet.The optional addition of Ti, V or Nb can support the creation of a finer-grain structure and promote the bainitic transformation. In addition, these micro-alloy elements contribute to the increase in hardness through the formation of precipitates. The positive effects of Ti, V and Nb in the cold-rolled flat steel product according to the invention can be used particularly effectively if their content is in the range of 0.002-0.15% by weight, in particular does not exceed 0.1% by weight.

Si ist in einem erfindungsgemäßen Stahlflachprodukt in Gehalten von 0,4 - 2,5 Gew.-% vorhanden und bewirkt eine deutliche Mischkristallverfestigung. Um diesen Effekt besonders sicher zu nutzen, kann der Si-Gehalt auf mindestens 1,0 Gew.-% gesetzt werden. Ebenso kann es zur Vermeidung negativer Einflüsse zweckmäßig sein, den Si-Gehalt auf maximal 2 Gew.-% zu beschränken.Si is present in a flat steel product according to the invention in contents of 0.4-2.5% by weight and causes a significant solid solution strengthening. In order to use this effect particularly reliably, the Si content can be set to at least 1.0% by weight. It can also be used for To avoid negative influences, it is advisable to limit the Si content to a maximum of 2% by weight.

Al kann im erfindungsgemäß verarbeiteten Stahl den Si-Gehalt zu einem Teil ersetzen. Gleichzeitig wirkt Al wie auch Si bei der Stahlherstellung desoxidierend. Hierzu kann ein Mindestgehalt von 0,01 Gew.-% Al vorgesehen werden. Höhere Gehalte an Al erweisen sich beispielsweise dann als zweckmäßig, wenn durch die Zugabe von Al die Härte oder Zugfestigkeit des Stahls zu Gunsten einer verbesserten Verformbarkeit auf einen niedrigeren Wert eingestellt werden soll.Al can partially replace the Si content in the steel processed according to the invention. At the same time, Al, like Si, has a deoxidizing effect in steel production. For this purpose, a minimum content of 0.01% by weight Al can be provided. Higher contents of Al prove to be expedient, for example, when the hardness or tensile strength of the steel is to be adjusted to a lower value in favor of improved deformability by adding Al.

Eine weitere Funktion von Si und Al besteht darin, die Karbidbildung im Bainit zu unterdrücken und damit den Restaustenit durch gelösten C zu stabilisieren.Another function of Si and Al is to suppress the formation of carbide in the bainite and thus to stabilize the retained austenite through dissolved C.

Die positiven Einflüsse der gleichzeitigen Anwesenheit von Al und Si können dadurch besonders effektiv genutzt werden, wenn die Gehalte an Si und Al innerhalb der erfindungsgemäß vorgegebenen Grenzen folgende Bedingung erfüllen: %Si + 0,8%Al > 1,2 Gew.-% (mit %Si: jeweiliger Si-Gehalt in Gew.-%, %Al: jeweiliger Al-Gehalt in Gew.-%).The positive influences of the simultaneous presence of Al and Si can be used particularly effectively if the Si and Al contents meet the following condition within the limits specified according to the invention:% Si + 0.8% Al> 1.2% by weight ( with% Si: respective Si content in% by weight,% Al: respective Al content in% by weight).

Die Bildung des erfindungsgemäß vorgegebenen Gefüges lässt sich insbesondere dadurch gewährleisten, dass die Gehalte des erfindungsgemäß verarbeiteten Stahls und dementsprechend die Gehalte des erfindungsgemäßen Stahlflachprodukts an Mn, Cr, Ni, Cu und C die folgende Bedingung 1 < 0,5%Mn + 0,167%Cr + 0,125%Ni + 0,125%Cu + 1,334%C < 2 erfüllen, wobei mit %Mn der jeweilige Mn-Gehalt in Gew.-%, mit %Cr der jeweilige Cr-Gehalt in Gew.-%, mit %Ni der jeweilige Ni-Gehalt in Gew.-%, mit %Cu der jeweilige Cu-Gehalt in Gew.-% und mit %C der jeweilige C-Gehalt in Gew.-% bezeichnet sind.The formation of the structure specified according to the invention can in particular be ensured by the fact that the Mn, Cr, Ni, Cu and C contents of the steel processed according to the invention and accordingly the Mn, Cr, Ni, Cu and C contents of the steel flat product according to the invention meet the following condition 1 <0.5% Mn + 0.167% Cr + 0.125% Ni + 0.125% Cu + 1.334% C <2, with% Mn the respective Mn content in% by weight, with% Cr the respective Cr content in wt .-%, with% Ni the respective Ni content in wt .-%, with% Cu the respective Cu content in wt .-% and with% C the respective C content in wt .-%.

Zur Herstellung eines erfindungsgemäßen Stahlflachprodukts wird das aus einem erfindungsgemäß zusammengesetzten Stahl gegossene Vorprodukt zunächst auf eine Temperatur gebracht oder auf einer Temperatur gehalten, die ausreicht, um das ausgehend von dieser Temperatur durchgeführte Warmwalzen bei einer Warmwalzendtemperatur zu beenden, die im Bereich von 830 - 1000 °C liegen. Nach dem Verlassen des letzten für das Warmwalzen verwendeten Walzgerüsts kühlt das Warmband auf dem sich an das betreffende Walzgerüst anschließenden Rollgang ab. Im Anschluss an den Rollgang läuft das Warmband in eine Haspeleinrichtung, in der es zu einem Coil gewickelt wird.To produce a steel flat product according to the invention, the intermediate product cast from a steel composed according to the invention is first brought to a temperature or kept at a temperature sufficient to end the hot rolling carried out starting from this temperature at a hot rolling end temperature in the range of 830-1000 ° C lie. After leaving the last roll stand used for hot rolling, the hot strip cools down on the roller table following the roll stand in question. After the roller table, the hot strip runs into a coiler, in which it is wound into a coil.

Die Haspeltemperatur muss mindestens 560 °C betragen, damit ein relativ weiches Warmbandgefüge aus Ferrit und Perlit entsteht. Ein für diesen Zweck optimaler Temperaturverlauf ergibt sich, wenn die Warmwalzendtemperatur im Bereich von 850 - 950 °C, insbesondere im Bereich von 880 - 950 °C, liegt. Typischerweise wird dazu das Vorprodukt vor dem Warmwalzen auf eine im Bereich von 1100 - 1300 °C liegende Temperatur erwärmt oder bei dieser Temperatur gehalten. Das Gefüge des so erhaltenen Warmbands besteht hauptsächlich aus Ferrit und Perlit. Die Gefahr einer Entstehung von Korngrenzenoxidation kann dadurch minimiert werden, dass die Haspeltemperatur auf maximal 750 °C beschränkt wird.The coiling temperature must be at least 560 ° C so that a relatively soft hot strip structure made of ferrite and pearlite is created. An optimal temperature profile for this purpose is obtained when the final hot rolling temperature is in the range from 850 to 950 ° C, in particular in the range from 880 to 950 ° C. For this purpose, the intermediate product is typically heated to a temperature in the range of 1100-1300 ° C. or kept at this temperature before hot rolling. The structure of the hot strip obtained in this way exists mainly made of ferrite and pearlite. The risk of grain boundary oxidation occurring can be minimized by limiting the coiling temperature to a maximum of 750 ° C.

Nach dem Haspeln wird das Warmband kaltgewalzt, wobei das Warmband vor dem Kaltwalzen selbstverständlich in üblicher Weise chemisch oder mechanisch entzundert werden kann.After coiling, the hot strip is cold-rolled, it being understood that the hot strip can of course be descaled chemically or mechanically in the usual way before cold-rolling.

Das Kaltwalzen erfolgt mit einem Kaltwalzgrad von mindestens 30 %, insbesondere mindestens 45 %, um die Rekristallisation und Umwandlung beim anschließenden Glühen zu beschleunigen. Generell ergibt sich zudem durch Einhaltung eines entsprechend hohen Kaltwalzgrades eine bessere Oberflächenqualität. Kaltwalzgrade von mindestens 50 % haben sich hierfür als besonders günstig erwiesen.The cold rolling takes place with a degree of cold rolling of at least 30%, in particular at least 45%, in order to accelerate the recrystallization and conversion during the subsequent annealing. In general, maintaining a correspondingly high degree of cold rolling also results in a better surface quality. Cold rolling degrees of at least 50% have proven to be particularly favorable for this.

Nach dem Kaltwalzen absolviert das erfindungsgemäß erhaltene Kaltband in einem kontinuierlichen Durchlauf einen Glühzyklus, bei dem es in einer ersten Glühphase auf eine Temperatur von mindestens 800 °C, bevorzugt mindestens 830 °C, erwärmt wird. Diese erste Glühphase dauert mindestens so lange, dass das Kaltband vollständig austenitisiert ist. Hierzu sind typischerweise 50 - 150 s erforderlich.After cold rolling, the cold strip obtained according to the invention undergoes an annealing cycle in one continuous run, in which it is heated to a temperature of at least 800 ° C., preferably at least 830 ° C., in a first annealing phase. This first annealing phase lasts at least long enough for the cold strip to be completely austenitized. This typically takes 50 - 150 s.

Am Ende der ersten Glühphase wird das Produkt abgeschreckt, wobei die Abkühlgeschwindigkeit mindestens 8 °C/s, insbesondere 10 °C/s, beträgt. Die Zieltemperatur dieser Abschreckung ist eine Haltetemperatur, die höchstens 470 °C beträgt und höher ist als die Martensitstarttemperatur MS, ab der Martensit im Gefüge des Kaltbands entsteht. In der Praxis kann als Anhalt für den Bereich, in dem die Haltetemperatur liegen soll, der Bereich von 300 - 420 °C, insbesondere 330 - 420 °C, angewendet werden.At the end of the first annealing phase, the product is quenched, the cooling rate being at least 8 ° C./s, in particular 10 ° C./s. The target temperature of this quenching is a holding temperature which is 470 ° C or less and higher than that Martensite start temperature MS, from which martensite occurs in the structure of the cold strip. In practice, the range of 300-420 ° C, in particular 330-420 ° C, can be used as a guide for the range in which the holding temperature should be.

Ausgehend von der jeweiligen Haltetemperatur wird das Kaltband in der zweiten Glühphase im Haltetemperaturbereich gehalten und zwar so lange, bis sich das Gefüge des Kaltbands zu mindestens 20 Vol.-% in Bainit gewandelt hat. Das Halten kann dabei als isothermes Halten auf der bei der Abkühlung erreichten Haltetemperatur oder als langsam erfolgende Temperaturabnahme innerhalb des Haltetemperaturbereichs durchgeführt werden.Starting from the respective holding temperature, the cold strip is held in the holding temperature range in the second annealing phase until the structure of the cold strip has changed to at least 20% by volume in bainite. The holding can be carried out as isothermal holding at the holding temperature reached during cooling or as a slow temperature decrease within the holding temperature range.

Das erfindungsgemäß erzeugte Stahlflachprodukt kann in üblicher Weise mit einer metallischen Schutzschicht belegt werden. Dies kann beispielsweise durch Schmelztauchbeschichten erfolgen. Sofern vor dem Auftrag der metallischen Beschichtung ein Glühen erforderlich ist, kann die erfindungsgemäß vorgesehene Wärmebehandlung im Rahmen dieses Glühens durchgeführt werden. Nachfolgend wird die Erfindung anhand von Ausführungsbeispielen näher erläutert.The flat steel product produced according to the invention can be covered in the usual way with a metallic protective layer. This can be done, for example, by hot dip coating. If an annealing is required before the application of the metallic coating, the heat treatment provided according to the invention can be carried out within the scope of this annealing. The invention is explained in more detail below on the basis of exemplary embodiments.

Es sind fünf Stähle S1 - S5 erschmolzen worden, deren Zusammensetzung in Tabelle 1 angegeben ist.Five steels S1 - S5 were melted, the composition of which is given in Table 1.

Stahl S5 ist nicht erfindugsgemäss.Steel S5 is not according to the invention.

Die entsprechend zusammengesetzten Stahlschmelzen sind auf konventionelle Weise zu einem Strang vergossen worden, von dem Brammen abgeteilt worden sind. Die Dünnbrammen sind anschließend auf ebenso konventionelle Weise auf eine Wiedererwärmungstemperatur erwärmt worden.The correspondingly composed steel melts are cast in a conventional manner to form a strand from which slabs have been separated. The thin slabs were then reheated to a reheating temperature in an equally conventional manner.

Die erwärmten Brammen sind in einer ebenfalls konventionellen Warmwalzstaffel zu Warmbändern mit einer Dicke von 2 mm warmgewalzt worden.The heated slabs were hot-rolled into hot strips with a thickness of 2 mm in a likewise conventional hot-rolling stage.

Die Warmwalzendtemperatur lag jeweils im Bereich von 830 - 900 °C. Ausgehend von dieser Temperatur sind die Warmbänder auf eine oberhalb von 560 °C liegende Haspeltemperatur abgekühlt worden und anschließend zu Coils gehaspelt worden.The final hot rolling temperature was in the range of 830-900 ° C. Starting from this temperature, the hot strips were cooled to a coiling temperature above 560 ° C. and then reeled into coils.

Die so erhaltenen Warmbänder sind nach dem Haspeln entzundert und nach dem Entzundern bei Kaltwalzgraden von 50 % zu Kaltband kaltgewalzt worden.The hot strips obtained in this way have been descaled after coiling and, after descaling, have been cold-rolled to cold strip at cold rolling degrees of 50%.

Eine größere Zahl von Proben dieser Kaltbänder sind dann einer Wärmebehandlung unterzogen worden, bei der sie in einem ersten Glühschritt mit einer Erwärmungsgeschwindigkeit von mindestens 1,9 °C/s auf eine erste Glühtemperatur erwärmt worden sind, die im Bereich von 830 - 850 °C lag. Bei dieser Temperatur sind die Kaltbänder über eine Dauer von 120 s gehalten worden, bis sie vollständig durcherwärmt waren.A large number of samples of these cold strips were then subjected to a heat treatment in which they were heated in a first annealing step at a heating rate of at least 1.9 ° C / s to a first annealing temperature in the range of 830 - 850 ° C lay. The cold strips were held at this temperature for a period of 120 seconds until they were completely heated.

Anschließend erfolgte eine Abschreckung, bei der Kaltbänder mit einer mindestens 8 °C/s betragenden Abkühlgeschwindigkeit auf eine Haltetemperatur T2 abgeschreckt worden sind, die im Bereich von 350 - 420 °C lag. Konkret lagen die Haltetemperaturen T2 bei einer ersten Charge von Versuchen bei 300 °C, 310 °C, 330 °C, 340 °C, 375 °C, 390 °C und 410 °C. Bei der jeweiligen Haltetemperatur T2 sind die Kaltbandproben für eine Glühdauer t2 gehalten worden.This was followed by quenching, in which cold strips were quenched at a cooling rate of at least 8 ° C / s to a holding temperature T2, which was in the range of 350-420 ° C. Specifically, the holding temperatures T2 were one first batch of tests at 300 ° C, 310 ° C, 330 ° C, 340 ° C, 375 ° C, 390 ° C and 410 ° C. At the respective holding temperature T2, the cold strip samples were held for an annealing period t2.

In Fig. 1 sind die erzielten Zugfestigkeiten Rm über die jeweilige Glühtemperatur T2 aufgetragen. Es zeigt sich, dass die aus dem Stahl S5 gefertigten Kaltbandproben jeweils nur unter bestimmten Glühbedingungen die geforderte Mindestzugfestigkeit von 1400 MPa erreichen, während die Zugfestigkeiten der aus den anderen Stählen hergestellten Kaltbandproben stets sicher über der Mindestgrenze von 1400 MPa lagen. Als Grund hierfür ist der vergleichbar geringe, an der unteren Grenze des erfindungsgemäß vorgegebenen Gehaltsbereichs liegende Kohlenstoffgehalt des Stahls S5 ermittelt worden.In Fig. 1 the achieved tensile strengths Rm are plotted against the respective annealing temperature T2. It can be seen that the cold strip specimens made from steel S5 only achieve the required minimum tensile strength of 1400 MPa under certain annealing conditions, while the tensile strengths of the cold strip specimens made from the other steels were always safely above the minimum limit of 1400 MPa. The reason for this was determined to be the comparatively low carbon content of steel S5, which is at the lower limit of the content range specified according to the invention.

In Fig. 2 sind die Zugfestigkeiten der aus dem Stahl S4 erzeugten Kaltbandproben über die Glühdauer t2 der zweiten Glühstufe aufgetragen. Es zeigt sich, dass die bei einer Haltetemperatur von 310 °C, 330 °C und 350 °C, also im Haltetemperaturbereich von 310 - 350 °C, gehaltenen Kaltbandproben die geforderte Zugfestigkeit Rm von 1400 MPa unabhängig von der jeweiligen Glühdauer t2 erreicht haben.In Fig. 2 the tensile strengths of the cold strip samples produced from steel S4 are plotted over the annealing duration t2 of the second annealing stage. It can be seen that the cold strip samples held at a holding temperature of 310 ° C, 330 ° C and 350 ° C, i.e. in the holding temperature range of 310 - 350 ° C, reached the required tensile strength Rm of 1400 MPa regardless of the respective annealing duration t2.

In Fig. 3 sind in gleicher Weise die Zugfestigkeiten der aus dem Stahl S5 erzeugten Kaltbandproben über die Glühdauer t2 der zweiten Glühstufe aufgetragen. Es zeigt sich hier, dass die bei einer Haltetemperatur von 350 °C und 390 °C, also im Haltetemperaturbereich von 350 - 390 °C, gehaltenen Kaltbandproben die geforderte Zugfestigkeit Rm von 1400 MPa erreichen, wenn die Glühdauer t2 kürzer als 145 s ist.In Fig. 3 the tensile strengths of the cold strip samples produced from steel S5 are plotted in the same way over the annealing time t2 of the second annealing stage. It can be seen here that the cold strip samples held at a holding temperature of 350 ° C and 390 ° C, i.e. in the holding temperature range of 350 - 390 ° C, met the requirements Achieve tensile strength Rm of 1400 MPa if the annealing time t2 is shorter than 145 s.

In Fig. 4 ist die Dehnung A80 der aus dem Stahl S4 erzeugten Kaltbandproben über die Glühdauer t2 der zweiten Glühstufe aufgetragen. Die bei einer Haltetemperatur von 310 °C, 330 °C und 350 °C, also im Haltetemperaturbereich von 310 - 350 °C, gehaltenen Kaltbandproben haben die geforderte Mindestdehnung A80 unabhängig von der jeweiligen Glühdauer t2 erreicht.In Fig. 4 the elongation A80 of the cold strip samples produced from steel S4 is plotted over the annealing duration t2 of the second annealing stage. The cold strip specimens held at a holding temperature of 310 ° C, 330 ° C and 350 ° C, i.e. in the holding temperature range of 310 - 350 ° C, have achieved the required minimum elongation A80 regardless of the respective annealing duration t2.

In Fig. 5 ist die Dehnung A80 der aus dem Stahl S5 erzeugten Kaltbandproben über die Glühdauer t2 der zweiten Glühstufe aufgetragen. Auch hier zeigt sich, dass die Kaltbandproben die geforderte Dehnung A80 von mindestens 5 % unabhängig von ihrer jeweiligen Haltetemperatur T2 und unabhängig von der jeweiligen Glühdauer t2 erreichen. Dementsprechend kann bei Einhaltung einer kurzen Glühdauer und geeignet niedrigen Haltetemperaturen T2 auch aus dem Stahl S5 trotz seines vergleichsweise niedrigen C-Gehalts ein erfindungsgemäßes kaltgewalztes Stahlflachprodukt erzeugt werden, bei dem eine hohe Zugfestigkeit Rm mit einer ausreichenden Dehnung A80 kombiniert ist.In Fig. 5 the elongation A80 of the cold strip samples produced from steel S5 is plotted over the annealing duration t2 of the second annealing stage. Here, too, it can be seen that the cold strip samples achieve the required elongation A80 of at least 5% regardless of their respective holding temperature T2 and regardless of the respective annealing duration t2. Accordingly, if a short annealing time and suitably low holding temperatures T2 are maintained, a cold-rolled flat steel product according to the invention can also be produced from steel S5 despite its comparatively low C content, in which a high tensile strength Rm is combined with sufficient elongation A80.

In Fig. 6 ist in einem Ausschnitt eine Vergrößerung eines Querschnitts eines erfindungsgemäßen Kaltbands dargestellt. Dabei sind beispielhaft Restaustenitblöcke RA-b markiert und eine Stelle durch eine Umkreisung hervorgehoben, an der filmartiger Restaustenit RA-f in einer lamellenartigen Schichtung vorliegt. Tabelle 1 Stahl C Mn Si Cu Cr Ti Nb V Al N Sonstige S1 0,52 1,48 0,40 1,51 0,88 0,009 - 0,093 1,400 - - S2 0,301 1,41 1,46 1,47 0,87 0, 014 0,005 0,09 0,021 0,0015 Ni: 0,021 Mo: <0,002 S3 0,505 1,50 0,40 0,6 1,30 0,011 - 0,098 0,012 0,002 Ni: 0,63 Mo: 0,30 S4 0,384 1,97 0,41 0,57 1,37 0,0016 - <0,0005 0,018 0,0014 Ni: 0,59 Mo: 0,30 S5 0,252 1,47 2,15 0,32 0,41 0,020 - 0,11 0,009 - Ni: 0,02 Mo: <0,002 Angaben in Gew.-%,
Rest Eisen und unvermeidbare Verunreinigungen In Fig. 6 an enlargement of a cross section of a cold strip according to the invention is shown in a detail. In this case, retained austenite blocks RA-b are marked by way of example and a point is highlighted by a circle where film-like retained austenite RA-f is present in a lamellar layer. Table 1 steel C. Mn Si Cu Cr Ti Nb V Al N Others S1 0.52 1.48 0.40 1.51 0.88 0.009 - 0.093 1,400 - - S2 0.301 1.41 1.46 1.47 0.87 0, 014 0.005 0.09 0.021 0.0015 Ni: 0.021 Mo: <0.002 S3 0.505 1.50 0.40 0.6 1.30 0.011 - 0.098 0.012 0.002 Ni: 0.63 Mo: 0.30 S4 0.384 1.97 0.41 0.57 1.37 0.0016 - <0.0005 0.018 0.0014 Ni: 0.59 Mo: 0.30 S5 0.252 1.47 2.15 0.32 0.41 0.020 - 0.11 0.009 - Ni: 0.02 Mo: <0.002 Data in% by weight,
Remainder iron and unavoidable impurities

Claims (12)

  1. Cold-rolled flat steel product, with a tensile strength Rm of at least 1400 MPa and an elongation A80 of at least 5%, consisting in % by weight of: C: 0.27 to 0.60%, Si: 0.4 to 2.5%, Mn: 0.4 to 3.0%, Cr: 0.3 to 2%,
    and in each case optionally of Al: up to 3.0%, Ni: up to 1.0%, Cu: up to 2.0%, Mo: up to 0.4%, Co: up to 1.5%, Ti: up to 0.2%, Nb: up to 0.2%, V: up to 0.5%,
    and the remainder of iron and unavoidable impurities, wherein the structure of the flat steel product consists at least 20% by volume of bainite, 10 to 35% by volume of residual austenite, which is predominantly present in a film-like manner with small globular islands of blocky residual austenite with a grain size of <5 µm and the remainder consisting of martensite.
  2. Flat steel product according to claim 1, characterised in that its Si content is at least 1.0% by weight.
  3. Flat steel product according to any one of the preceding claims, characterised in that its Al content is at least 0.01% by weight.
  4. Flat steel product according to any one of the preceding claims, characterised in that its Cu content is at least 0.2% by weight.
  5. Flat steel product according to claim 4, characterised in that its Cu content is at least 0.55% by weight.
  6. Flat steel product according to any one of the preceding claims, characterised in that its contents of Mn, Cr, Ni, Cu and C meet the following condition: 1 < 0.5 % Mn + 0.167 % Cr + 0.125 % Ni + 0.125 % Cu + 1.334 % C < 2
    Figure imgb0002
    with %Mn: respective Mn content in % by weight,
    %Cr: respective Cr content in % by weight,
    %Ni: respective Ni content in % by weight,
    %Cu: respective Cu content in % by weight,
    %C: respective C content in % by weight.
  7. Flat steel product according to any one of the preceding claims, characterised in that its structure contains at least 50% by volume of bainite.
  8. Flat steel product according to any one of the preceding claims, characterised in that its structure contains 10 to 25% by volume of residual austenite.
  9. Method for producing a flat steel product provided according to any one of claims 1 to 8, comprising the following work steps:
    - providing a primary product in the form of a slab, thin slab or a cast strip, which consists in % by weight of C: 0.27 to 0.60%, Si: 0.4 to 2.5%, Mn: 0.4 to 3.0%, Cr: 0.3 to 2% and in each case optionally of Al: up to 3.0%, Ni: up to 1.0%, Cu: up to 2.0%, Mo: up to 0.4%, Co: up to 1.5%, Ti: up to 0.2%, Nb: up to 0.2%, V: up to 0.5%, and the remainder of iron and unavoidable impurities;
    - heating the primary product to a temperature in the range of 1100 to 1300°C or holding the primary product at this temperature;
    - hot rolling the primary product to a hot strip in one or a plurality of rolling passes, wherein the obtained hot strip has a hot rolling final temperature of 830 to 1000°C upon leaving the last rolling pass;
    - coiling the obtained hot strip at a coiling temperature which lies between the hot rolling final temperature and 560°C;
    - cold rolling the hot strip to a cold strip with a cold rolling grade of at least 30%;
    - heat treating the obtained cold strip, wherein the cold strip during the heat treatment
    - is heated to an annealing temperature of at least 800°C, wherein the cold strip is held for an annealing time of 50 to 150 s at the annealing temperature,
    - is cooled proceeding from the annealing temperature at a cooling speed of at least 8°C/s to a holding temperature, which is in a holding temperature range, whose upper limit is 470°C and whose lower limit is higher than the martensite starting temperature MS, from which martensite develops in the structure of the cold strip and
    - is held at the holding temperature for a period that is sufficient to form at least 20% by volume of bainite in the structure of the cold strip.
  10. Method according to claim 9, characterised in that the hot rolling final temperature is 850 to 950°C.
  11. Method according to any one of claims 9 or 10, characterised in that the holding temperature is 300 to 420°C.
  12. Method according to any one of claims 9 to 11, characterised in that the cold strip is coated with a metallic protective layer after the heat treatment.
EP12178332.8A 2012-07-27 2012-07-27 Produit plat en acier laminé à froid et son procédé de fabrication Active EP2690184B1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
EP12178332.8A EP2690184B1 (en) 2012-07-27 2012-07-27 Produit plat en acier laminé à froid et son procédé de fabrication
US14/417,659 US20150218684A1 (en) 2012-07-27 2013-07-26 Cold-Rolled Flat Steel Product and Method for the Production Thereof
PCT/EP2013/065838 WO2014016421A1 (en) 2012-07-27 2013-07-26 Cold-rolled flat steel product and method for the production thereof
JP2015523569A JP6202579B2 (en) 2012-07-27 2013-07-26 Cold rolled flat steel product and method for producing the same
CN201380048837.7A CN104641008B (en) 2012-07-27 2013-07-26 Flat cold-rolled bar product and manufacture method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP12178332.8A EP2690184B1 (en) 2012-07-27 2012-07-27 Produit plat en acier laminé à froid et son procédé de fabrication

Publications (2)

Publication Number Publication Date
EP2690184A1 EP2690184A1 (en) 2014-01-29
EP2690184B1 true EP2690184B1 (en) 2020-09-02

Family

ID=48877247

Family Applications (1)

Application Number Title Priority Date Filing Date
EP12178332.8A Active EP2690184B1 (en) 2012-07-27 2012-07-27 Produit plat en acier laminé à froid et son procédé de fabrication

Country Status (4)

Country Link
US (1) US20150218684A1 (en)
EP (1) EP2690184B1 (en)
JP (1) JP6202579B2 (en)
WO (1) WO2014016421A1 (en)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108474080B (en) 2015-11-16 2021-09-21 本特勒尔钢管有限公司 Steel alloy and steel pipe product with high energy absorption capacity
DE102015119839A1 (en) * 2015-11-17 2017-05-18 Benteler Steel/Tube Gmbh High energy absorbing steel alloy and tubular steel product
WO2017109539A1 (en) * 2015-12-21 2017-06-29 Arcelormittal Method for producing a high strength steel sheet having improved strength and formability, and obtained high strength steel sheet
CN108603259B (en) * 2016-02-19 2020-11-06 日本制铁株式会社 Steel having high strength and excellent low-temperature toughness after quenching and tempering
KR101822292B1 (en) 2016-08-17 2018-01-26 현대자동차주식회사 High strength special steel
KR101822295B1 (en) 2016-09-09 2018-01-26 현대자동차주식회사 High strength special steel
DE102017209982A1 (en) * 2017-06-13 2018-12-13 Thyssenkrupp Ag High strength steel sheet with improved formability
CN108546881B (en) * 2018-05-16 2020-06-26 东北大学 Preparation method of yield-platform-free cold-rolled medium manganese steel thin strip
DE102021119047A1 (en) 2021-07-22 2023-01-26 Thyssenkrupp Steel Europe Ag Method for producing a cold-rolled flat steel product with a bainitic matrix and cold-rolled flat steel product with a bainitic matrix

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2834722B1 (en) 2002-01-14 2004-12-24 Usinor MANUFACTURING PROCESS OF A COPPER-RICH CARBON STEEL STEEL PRODUCT, AND THUS OBTAINED STEEL PRODUCT
EP1553202A1 (en) * 2004-01-09 2005-07-13 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Ultra-high strength steel sheet having excellent hydrogen embrittlement resistance, and method for manufacturing the same
EP1559798B1 (en) 2004-01-28 2016-11-02 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) High strength and low yield ratio cold rolled steel sheet and method of manufacturing the same
CN101351570B (en) * 2005-12-28 2013-01-30 株式会社神户制钢所 Ultrahigh-strength thin steel sheet
EP1832667A1 (en) * 2006-03-07 2007-09-12 ARCELOR France Method of producing steel sheets having high strength, ductility and toughness and thus produced sheets.
JP4164537B2 (en) * 2006-12-11 2008-10-15 株式会社神戸製鋼所 High strength thin steel sheet
EP1990431A1 (en) * 2007-05-11 2008-11-12 ArcelorMittal France Method of manufacturing annealed, very high-resistance, cold-laminated steel sheets, and sheets produced thereby
JP5365217B2 (en) * 2008-01-31 2013-12-11 Ｊｆｅスチール株式会社 High strength steel plate and manufacturing method thereof
JP5402007B2 (en) * 2008-02-08 2014-01-29 Ｊｆｅスチール株式会社 High-strength hot-dip galvanized steel sheet excellent in workability and manufacturing method thereof
JP5418047B2 (en) * 2008-09-10 2014-02-19 Ｊｆｅスチール株式会社 High strength steel plate and manufacturing method thereof
JP2010065272A (en) * 2008-09-10 2010-03-25 Jfe Steel Corp High-strength steel sheet and method for manufacturing the same
JP5365112B2 (en) * 2008-09-10 2013-12-11 Ｊｆｅスチール株式会社 High strength steel plate and manufacturing method thereof
JP5504636B2 (en) * 2009-02-04 2014-05-28 Ｊｆｅスチール株式会社 High strength hot rolled steel sheet and method for producing the same
JP5412182B2 (en) * 2009-05-29 2014-02-12 株式会社神戸製鋼所 High strength steel plate with excellent hydrogen embrittlement resistance
JP5287770B2 (en) * 2010-03-09 2013-09-11 Ｊｆｅスチール株式会社 High strength steel plate and manufacturing method thereof
JP5327106B2 (en) * 2010-03-09 2013-10-30 Ｊｆｅスチール株式会社 Press member and manufacturing method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Also Published As

Publication number Publication date
WO2014016421A1 (en) 2014-01-30
CN104641008A (en) 2015-05-20
EP2690184A1 (en) 2014-01-29
JP6202579B2 (en) 2017-09-27
US20150218684A1 (en) 2015-08-06
JP2015528065A (en) 2015-09-24

Similar Documents

Publication Publication Date Title
EP2690184B1 (en) Produit plat en acier laminé à froid et son procédé de fabrication
EP2690183B1 (en) Hot-rolled steel flat product and method for its production
EP2028282B1 (en) Dual-phase steel, flat product made of such dual-phase steel and method for manufacturing a flat product
DE60125253T2 (en) High strength hot rolled steel sheet with excellent stretch aging properties
EP2855717B1 (en) Steel sheet and method to manufacture it
EP2809819B1 (en) Ultrahigh-strength multiphase steel having improved properties during production and processing
EP3655560B1 (en) Flat steel product with a high degree of aging resistance, and method for producing same
EP2668302B1 (en) Method for manufacturing a strip from a high strength multi-phase steel having excellent forming properties
EP2840159B1 (en) Method for producing a steel component
EP3535431B1 (en) Steel product with an intermediate manganese content for low temperature application and production method thereof
EP2663411A1 (en) Method for producing a hot-rolled flat steel product
EP3504349B1 (en) Method for producing a high-strength steel strip with improved properties for further processing, and a steel strip of this type
EP2905348B1 (en) High strength flat steel product with bainitic-martensitic structure and method for manufacturing such a flat steel product
WO2016078642A1 (en) High-strength air-hardening multi-phase steel comprising outstanding processing properties and method for the production of a steel strip from said steel
WO2016078644A1 (en) Ultra high-strength air-hardening multiphase steel having excellent processing properties, and method for manufacturing a strip of said steel
EP1319725B1 (en) Hot strip manufacturing process
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
DE102024104377A1 (en) Sheet metal part with improved cathodic corrosion protection
WO2024068957A1 (en) Method for producing a steel strip from a high-strength multiphase steel, and the corresponding steel strip
WO2023025635A1 (en) Cold-rolled flat steel product and method for the production thereof
EP4174207A1 (en) Flat steel product having improved processing properties
WO2021213647A1 (en) Hot-rolled flat steel product and method for the production thereof

Legal Events

Date Code Title Description
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

AK Designated contracting states

Kind code of ref document: A1

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

17P Request for examination filed

Effective date: 20140728

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: 20180307

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: 20200310

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: AT

Ref legal event code: REF

Ref document number: 1308863

Country of ref document: AT

Kind code of ref document: T

Effective date: 20200915

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 502012016329

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: LT

Ref legal event code: MG4D

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

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: 20200902

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: 20200902

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: 20201202

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: 20201203

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: 20201202

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: 20200902

Ref country code: SE

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: 20200902

REG Reference to a national code

Ref country code: NL

Ref legal event code: MP

Effective date: 20200902

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

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: 20200902

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: 20200902

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: 20200902

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

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: 20210104

Ref country code: NL

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: 20200902

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: 20200902

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: 20200902

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: 20200902

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: 20200902

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: 20200902

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: 20210102

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: 20200902

REG Reference to a national code

Ref country code: DE

Ref legal event code: R097

Ref document number: 502012016329

Country of ref document: DE

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: 20200902

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

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

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20210603

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: 20200902

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: 20200902

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

Ref country code: IT

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: 20200902

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 502012016329

Country of ref document: DE

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

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

Effective date: 20210727

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

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: 20200902

REG Reference to a national code

Ref country code: BE

Ref legal event code: MM

Effective date: 20210731

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: 20210731

Ref country code: GB

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

Effective date: 20210727

Ref country code: DE

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

Effective date: 20220201

Ref country code: CH

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

Effective date: 20210731

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

Ref country code: LU

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

Effective date: 20210727

Ref country code: FR

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

Effective date: 20210731

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: 20210727

Ref country code: BE

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

Effective date: 20210731

REG Reference to a national code

Ref country code: AT

Ref legal event code: MM01

Ref document number: 1308863

Country of ref document: AT

Kind code of ref document: T

Effective date: 20210727

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

Ref country code: AT

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

Effective date: 20210727

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

Ref country code: HU

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

Effective date: 20120727

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: 20200902