EP0914480A1 - Process for producing an easily shaped cold-rolled sheet or strip - Google Patents

Process for producing an easily shaped cold-rolled sheet or strip

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Publication number
EP0914480A1
EP0914480A1 EP97922915A EP97922915A EP0914480A1 EP 0914480 A1 EP0914480 A1 EP 0914480A1 EP 97922915 A EP97922915 A EP 97922915A EP 97922915 A EP97922915 A EP 97922915A EP 0914480 A1 EP0914480 A1 EP 0914480A1
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EP
European Patent Office
Prior art keywords
temperature
cold
strip
max
hot
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.)
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Application number
EP97922915A
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German (de)
French (fr)
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EP0914480B1 (en
Inventor
Ilse Heckelmann
Ullrich Heidtmann
Rolf Bode
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ThyssenKrupp Steel Europe AG
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Thyssen Stahl AG
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0473—Final recrystallisation annealing
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
    • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
    • C23C2/0224—Two or more thermal pretreatments
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0426—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0436—Cold rolling

Definitions

  • the invention relates to a method for producing a cold-rolled, high-strength steel sheet or strip with good formability, in particular stretch-pullability, for the production of pressed parts with high buckling stiffness.
  • the pressed parts should have a high basic material strength and, after an additional heat treatment, as is usually used in painting, should receive additional material hardening ("bake hardening"). This gives excellent buckling stiffness properties.
  • Pressed parts with a high proportion of drawn parts are e.g. flat body parts in the automotive industry, such as doors, hoods, roofs.
  • Recrystallization temperature an additional annealing, the so-called aging annealing, applied to ensure aging resistance.
  • An aging-resistant material is characterized in that no significant changes in the material properties occur even after prolonged storage times, and error-free, flow figure-free processing is possible. In a continuous furnace, this treatment can take place in an aging section of the line. Subsequent external annealing, usually in the bundle, must be carried out on strips that are produced in a conventional fire coating system.
  • the carbon content is included the AI-calmed unalloyed deep-drawing steels, also called "low-carbon" (LC) steels, in the range 0.02 to 0.08%.
  • the use of the thinnest possible sheet metal is desirable in order to save weight.
  • higher strengths are necessary.
  • Bake hardening steels are increasingly used for this. Steels with bake hardening properties are characterized by an additional increase in the yield strength on the drawn component. This is achieved in that the material, in addition to the deformation hardening that occurs during pressing ("work hardening"), also undergoes an additional increase in strength when baked-on, "bake hardening".
  • the physical cause is a controlled carbon aging. For bake-hardening steels and their field of application, sufficient aging resistance for faultless surfaces after pressing is also necessary.
  • An unalloyed LC steel can also be produced as bake-hardening steel in continuous furnaces that have an aging part in line by precisely matching the chemical steel composition, cooling rate and aging condition. This process is already being used on an industrial scale. Optimization of the production conditions is described, for example, by Haya ⁇ hida et al. (T. Hayashida, M. Oda, T. Yamada, Y. Mat ⁇ ukawa, J. Tanaka: "Development and applications of continuous-annealed low-carbon Al-killed BH steel Sheets", Poe. Of the Symp. On High-Strength Sheet steels for the Automotive Industry, Baltimore, October 16-19, 1994, p.135).
  • the aim is the complete setting of the nitrogen in titanium nitrides, although a small amount of carbon must remain in solution to ensure the bake-hardening effect. Generation in vacuum degassing plants is necessary.
  • the advantage of this process is that the annealing annealing is no longer necessary, which makes it suitable for hot-dip coating systems.
  • the bake-hardening parameters determined in the tensile test after 2% pre-stretching (BH 2 value) reach approximately 40 N / mm 2 for the steels produced in this way.
  • the yield strengths are around 200 N / mm 2
  • the values for the mean vertical anisotropy (r-value) are around 1.8.
  • EP 0 620 288 A1 discloses a process for producing only cold-rolled or fire-coated cold-rolled steel strip in continuous strip lines, which, in addition to being resistant to aging, has high bake hardening properties and good deep-drawing properties due to high r values.
  • a ULC steel itself or a ULC steel with either a titanium or a niobium alloy is annealed above the Ac 3 conversion temperature, ie in the austenite area.
  • the bake-harding values reach 100 N / mm 2 .
  • An aging glow is not necessary.
  • ULC steel the steel production must take place in a vacuum degassing plant. Difficulties with regard to strip flatness are caused by the necessary high annealing temperatures. A large-scale application of this method is not known.
  • processes previously used or described in the literature for the production of readily deformable cold thin sheet with bake-hardening properties in continuous strip systems either include the additional annealing treatment described above for the case of using a soft, unalloyed, AI-soaked deep-drawing steel, which results in production not allowed in a common fire coating system, or must the more complex to produce ULC steels with very low carbon contents can be used.
  • the above-described methods based on ULC steels mainly include steels with yield strengths in the lower range up to 240 N / mm 2 . Because of the high average r values (> 1.5), they are suitable for pressed parts with a high proportion of deep-drawn parts.
  • the task derived from this is to produce a readily deformable, high-strength cold-rolled steel sheet or strip in a continuous strip line without a subsequent aging annealing treatment, which also has good bake-hardening properties.
  • the combination of the high basic material strength and the bake-hardening potential should lead to excellent buckling stiffness of the pressed parts.
  • Balance iron and unavoidable impurities including max. 0.08% P and max. 0.02% S, proposed, consisting of preheating the cast slab to a temperature above 1050 ° C, hot rolling with a final temperature in the range from above the Ar 3 temperature to 950 ° C, preferably in the range from 870 to 950 ° C, reeling the hot-rolled strip a temperature in the range of 550 to 750 ° C, cold rolling with a total cold rolling degree of 40 to 85%, recrystallizing annealing of the cold strip in a continuous furnace at a temperature of at least 720 ° C with subsequent high cooling rates of 5 to 70 K / s and final skin training.
  • the steel achieves its aging resistance by adding titanium to the nitrogen content. This leads to an early complete setting of the nitrogen, which is known to be an element which has a severe adverse effect on aging resistance.
  • the nitrogen in excess of the nitrogen setting, so that the formation of a minimum amount of titanium carbides is ensured.
  • the volume fraction and the number of titanium carbides must not be too high, however, so that the steel has the hardening characteristics necessary for the high forming demands and sufficient elongation and toughness properties. Therefore, the amount of the nitride former not bound to nitrogen should be 0.003 to 0.015% Ti or 0.0015 to 0.008% Nb.
  • niobium can also be used to form nitride and carbide.
  • the silicon content should preferably be max. 0.15% may be limited.
  • the economic advantage of the method according to the invention consists in the fact that the additional process step of the aging annealing to achieve the aging resistance is eliminated, although the steel composition is based on the analysis of soft, unalloyed Al-alloyed (LC) steels. On the basis of this analysis concept, steel production can take place without complex metallurgical production processes. In addition, titanium or niobium are only required in small quantities, so that the steel can also be produced inexpensively with regard to the addition of alloys.
  • the steel manufacturing process includes this
  • the cold strip should preferably be heated to the temperature of the recrystallization annealing at a speed in the range from 5 to 10 K / s.
  • the recrystallizing annealing can preferably be carried out in line with a hot-dip galvanizing plant.
  • the steel strips or sheets produced by the process according to the invention are distinguished by a high initial yield strength (greater than 240 N / mm 2 ) and a high strengthening capacity in the range of small plastic expansions. Together with low values of the vertical anisotropy, which characterize a preferred flow from the thickness, pressed parts with a high proportion of drawn parts, for example automobile outer skin parts, are the ideal area of application.
  • the strong solidification of this material which occurs even with small plastic deformations and is expressed in very high work hardening values, is an essential point for the properties of the product.
  • the strong solidification favors the transmission of force to neighboring material areas, as a result of which local material failure, eg constriction, is avoided.
  • Tables 2 and 3 show the mechanical properties and grain sizes of strips A and B determined in the tensile test, measured at an angle of 90 ° to the rolling direction. Only the r values and the values for the planar anisotropy are calculated as follows from three tensile specimens, which were taken in the angular positions 0 °, 45 ° and 90 ° to the rolling direction
  • the BH 0 value corresponds to the increase in the lower yield point after a heat treatment of 20 minutes at 170 ° C.
  • the size WH indicates the amount of deformation hardening when the tensile test is stretched by 2%. She is calculated by subtracting the yield strength Rp c: from the measured stress at 2% deformation.
  • the size BH 2 corresponds to the increase in the lower yield strength after a heat treatment of 20 minutes at 170 ° C, measured on the 2% pre-stretched tensile test.
  • the hot-dip galvanized cold-rolled strips made of steels A and B show an almost unchanged level of the lower or upper yield strength after artificial aging of 60 minutes at 100 ° C (Table 3).
  • the extent of the yield point elongation also remains below 0.5%, which means that the aging resistance is sufficient for processing without flow figures, even after long periods of storage.
  • the course of the differential (momentary) hardening exponent (n value) over the total elongation is in Fig. 1 for the steel AI (reel temperature 730 ° C) and in Fig. 2 for the steel A2 (coil temperature 600 ° C) applied.
  • the maxima of the differential n values are listed in Table 2; They reach at least 0.170 for steels A and B for both reel temperature classes, and even at least 0.180 for high reel temperatures.
  • the maximum n value of steels A and B is in the range of low total strains between 2 and 5%.
  • the yield strengths are about 50 N / mm 2 larger for the higher-coiled variants AI and B1 than for the low-coiled variants A2 and B2, so that the starting position of the yield strength can be determined by the choice of the coiler temperature.
  • the values for the mean vertical anisotropy for the steels AI, A2, B1 and B2 according to the invention are low at 1.0-1.1. Regardless of the reel temperature, they have isotropic properties with ⁇ r values between 0 and 0.3.
  • the work hardening values which represent a measure of the hardening by plastic deformation, are very high at approx. 50 N / mm 2 .
  • the Characteristic values for bake-hardening with or without pre-deformation in all cases at least 45 N / mm 2 .
  • the increase in yield strength after the painting treatment of a pressed part can be estimated by the sum WH + BH 2 .
  • these values are at least 100 N / mm 2 .
  • the sum WH + BH 2 with at least 60 N / mm 2 is still favorable.
  • Tables 1, 2 and 3 additionally list steels C to E for comparison, which, in contrast to steels A and B, either contain no titanium (steel E) or have titanium contents which are substoichiometric in relation to the nitrogen content (steels C and D with Ti / N ⁇ 3.4).
  • the values of the initial state, ie not aged, relate to the extracted state.
  • the increase in the lower yield strength (R el ) and the yield strength expansions after artificial aging are significantly higher for these comparative steels than for steels A and B produced according to the invention. Above all, the upper yield strength (deer) increases up to 70 N / mm 2 . Correct processing after long aging is not possible with steels C to E.
  • Steel F contains no titanium, but niobium. Due to the reel temperature of 600 ° C and the alloying with niobium, its yield strength is very high at 350 N / mm 2 .
  • the mean r value is 1.0 and the ⁇ r value is - 0.20, which is favorable for uniform forming behavior.
  • the lower and upper yield strength of the Nb-alloyed steel is also stable and the yield strength elongation is less than 1%, so that here too, processing without flow lines after longer storage times of the Material is possible.
  • the forming behavior of the steels AI and Bl produced according to the invention was extensively investigated in a practical large-scale test using molded automobile bonnets. With regard to the shape accuracy and surface of the pressed parts, perfect pressing results were achieved, which were reproducible even after processing after a storage period of 5 months.
  • the tensile tests were carried out on samples with measuring lengths of 80 mm.
  • ⁇ Reh after aging indicates the increase in the upper yield strength after artificial aging of the tensile samples (100 ° C, 60 minutes).
  • ⁇ n max is the total strain at which the maximum of the n value occurs.

Abstract

PCT No. PCT/EP97/02169 Sec. 371 Date Oct. 27, 1998 Sec. 102(e) Date Oct. 27, 1998 PCT Filed Apr. 26, 1997 PCT Pub. No. WO97/46720 PCT Pub. Date Dec. 11, 1997A method for producing a cold-rolled steel sheet or strip with good formability, especially stretch formability, for making pressings with a high buckling resistance from a steel comprising (in % by mass): 0.01 to 0.08% C, 0.10 to 0.80% Mn, maximum 0.15% Si, 0.015 to 0.08% Al, a maximum 0.005% N, 0.01 to 0.04% Ti and/or Nb, whose contents exceeding the quantity necessary for stoichiometric binding of the nitrogen, ranges from 0.003 to 0.015% Ti or 0.0015 to 0.008% Nb, and a maximum 0.15% in total of one or several elements from the group copper, vanadium, nickel, the remainder being iron, including unavoidable impurities, including a maximum 0.08% P and a maximum 0.02% S, comprises preheating the cast slab to a temperature exceeding 1050 DEG C., hot-rolling at a final temperature ranging from over the Ar3 temperature to 950 DEG C., coiling the hot-rolled strip at a temperature ranging from 550 to 750 DEG C., cold-rolling at a total cold-rolling degree of deformation from 40 to 85%, recrystallization annealing of the cold strip in a continuous furnace at a temperature of at least 720 DEG C., subsequent cooling at 5 to 70 K/s; and skin passing.

Description

Verfahren zur Erzeugung eines kaltgewalzten Stahlbleches oder -bandes mit guter UmformbarkeitProcess for producing a cold-rolled steel sheet or strip with good formability
Die Erfindung betrifft ein Verfahren zur Erzeugung eines kaltgewalzten höherfesten Stahlbleches oder -bandes mit guter Umformbarkeit, insbesondere Streckziehbarkeit zur Herstellung von Preßteilen mit hoher Beulsteifigkeit.The invention relates to a method for producing a cold-rolled, high-strength steel sheet or strip with good formability, in particular stretch-pullability, for the production of pressed parts with high buckling stiffness.
Die Preßteile sollen eine hohe Materialgrundfeεtigkeit haben und nach einer zusätzlichen Wärmebehandlung, wie sie üblicherweise beim Lackieren angewendet wird, eine zusätzliche Materialverfestigung ("Bake-hardening") erhalten. Dadurch werden hervorragende Beulsteifigkeits- eigenschaften erreicht. Preßteile mit hohem Streckziehanteil sind z.B. flache Karosserieteile in der Automobilindustrie, wie Türen, Hauben, Dächer.The pressed parts should have a high basic material strength and, after an additional heat treatment, as is usually used in painting, should receive additional material hardening ("bake hardening"). This gives excellent buckling stiffness properties. Pressed parts with a high proportion of drawn parts are e.g. flat body parts in the automotive industry, such as doors, hoods, roofs.
Bei der Herstellung von durchlaufgeglühten AI-beruhigten unlegierten Tiefziehstählen mit besonderen Umforman- sprüchen wird nach Abkühlung vonIn the production of continuously annealed, AI-calmed, unalloyed deep-drawing steels with special forming requirements, after cooling from
Rekristallisationstemperatur eine zusätzliche Glühung, die sogenannte Überalterungsglühung, angewendet um Alterungsbeständigkeit zu gewährleisten. Ein alterungsbeständiger Werkstoff ist dadurch gekennzeichnet, daß auch nach längeren Lagerzeiten keine nennenswerten Veränderungen der Werkstoffeigenschaften auftreten und eine fehlerfreie, fließfigurenfreie Weiterverarbeitung möglich ist. In einem Durchlaufofen 'kann diese Behandlung in einem Überalterungsteil der Linie erfolgen. Bei Bändern, die in einer gängigen Feuerbeschichtungsanlage erzeugt werden, muß eine anschließende externe Glühung, üblicherweise im Bund, durchgeführt werden. Der Gehalt an Kohlenstoff liegt bei den AI-beruhigten unlegierten Tiefziehstählen, auch "Low- carbon" (LC) -Stähle genannt, im Bereich 0,02 bis 0,08%.Recrystallization temperature an additional annealing, the so-called aging annealing, applied to ensure aging resistance. An aging-resistant material is characterized in that no significant changes in the material properties occur even after prolonged storage times, and error-free, flow figure-free processing is possible. In a continuous furnace, this treatment can take place in an aging section of the line. Subsequent external annealing, usually in the bundle, must be carried out on strips that are produced in a conventional fire coating system. The carbon content is included the AI-calmed unalloyed deep-drawing steels, also called "low-carbon" (LC) steels, in the range 0.02 to 0.08%.
Vor allem für den Automobilkarosseriebau ist aus Gründen der Gewichtseinsparung der Einsatz von möglichst dünnem Blech erwünscht. Um die erforderlichen Beulsteifigkeiten trotz Dickenreduzierung der Bleche zu gewährleisten, sind höhere Festigkeiten notwendig. Hierfür finden Bake- hardening Stähle zunehmend Einsatz. Stähle mit Bake- hardening Eigenschaften zeichnen sich durch eine zusätzliche Streckgrenzensteigerung am gezogenen Bauteil aus. Diese wird dadurch erreicht, daß der Werkstoff neben der beim Pressen auftretenden Verformungsverfestigung ("Work-hardening") noch eine zusätzliche Festigkeitε- εteigerung beim Einbrennlackieren, dem "Bake-hardening", erfährt. Die physikalische Ursache ist eine kontrolliert ablaufende Kohlenstoffalterung. Für Bake-hardening Stähle und deren Anwendungsgebiet ist eine ausreichende Alterungsbeständigkeit für fehlerfreie Oberflächen nach dem Verpresεen ebenfalls notwendig.Especially for automobile body construction, the use of the thinnest possible sheet metal is desirable in order to save weight. In order to ensure the required buckling stiffness despite reducing the thickness of the sheets, higher strengths are necessary. Bake hardening steels are increasingly used for this. Steels with bake hardening properties are characterized by an additional increase in the yield strength on the drawn component. This is achieved in that the material, in addition to the deformation hardening that occurs during pressing ("work hardening"), also undergoes an additional increase in strength when baked-on, "bake hardening". The physical cause is a controlled carbon aging. For bake-hardening steels and their field of application, sufficient aging resistance for faultless surfaces after pressing is also necessary.
Ein unlegierter LC-Stahl kann in DurchlaufÖfen, die einen Überalterungsteil in Linie besitzen, auch alε Bake- hardening Stahl erzeugt werden, indem chemische Stahlzusammensetzung, Abkühlrate und Überalterungs- bedingung genau aufeinander abgestimmt werden. Dieseε Verfahren wird bereits großtechnisch angewendet. Eine Optimierung der Erzeugungsbedingungen wird z.B. von Hayaεhida et al. (T. Hayashida, M. Oda, T. Yamada, Y. Matεukawa, J. Tanaka: "Development and applications of continuous-annealed low-carbon Al-killed BH steel Sheets", Poe. of the Symp. on High-Strength Sheet steels for the Automotive Industry, Baltimore, October 16-19, 1994, p.135) beschrieben. In anderen Verfahren zur Erzeugung von alterungsbe¬ ständigen kaltgewalzten Stählen mit Bake-hardening Eigenschaften in kontinuierlichen Bandanlagen werden niedrig gekohlte Stähle, sogenannte Ultra-low-carbon (ULC) Stähle, verwendet. N. Mizui, A. Okamoto, T. Tanioku: "Recent Development in Bake-hardenable Sheet Steel for Automotive Body Panels" ,- Internationale Tagung "Stahl im Automobilbau" , Würzburg 24.-26.9.1990) beschreiben ein Verfahren auf Basis eines mit Titan teilstabilisierten ULC-Stahles für Feuerbeschich¬ tungsanlagen. Der Kohlenstoffgehalt soll zwischen 15 und 25 ppm liegen. Der Titangehalt wird den Stickstoff- und Schwefelgehalten mit 48/14 N < Ti < 48 (N/14+S/32) angepaßt. Ziel ist die vollständige Abbindung des Stickstoffs in Titannitriden, wobei jedoch zur Gewährleistung des Bake-hardening Effektes eine geringe Menge an Kohlenstoff in Lösung bleiben muß. Eine Erzeugung in Vakuumentgasungsanlagen ist notwendig. Vorteil dieses Verfahrens ist der Wegfall der liberalterungsglühung, wodurch eine Eignung für Feuerbeschichtungsanlagen gegeben ist. Die im Zugversuch ermittelten Bake-hardening Kenngrößen nach 2 % Vordehnung (BH2-Wert) erreichen bei den so hergestellten Stählen cirka 40 N/mm2. Die Streckgrenzen liegen bei ca. 200 N/mm2, die Werte für die mittlere senkrechte Anisotropie (r-Wert) bei ca. 1,8.An unalloyed LC steel can also be produced as bake-hardening steel in continuous furnaces that have an aging part in line by precisely matching the chemical steel composition, cooling rate and aging condition. This process is already being used on an industrial scale. Optimization of the production conditions is described, for example, by Hayaεhida et al. (T. Hayashida, M. Oda, T. Yamada, Y. Matεukawa, J. Tanaka: "Development and applications of continuous-annealed low-carbon Al-killed BH steel Sheets", Poe. Of the Symp. On High-Strength Sheet steels for the Automotive Industry, Baltimore, October 16-19, 1994, p.135). In other processes for the production of age-resistant cold-rolled steels with bake-hardening properties in continuous strip plants, low-carbon steels, so-called ultra-low-carbon (ULC) steels, are used. N. Mizui, A. Okamoto, T. Tanioku: "Recent Development in Bake-hardenable Sheet Steel for Automotive Body Panels", - International conference "Stahl im Automobilbau", Würzburg, September 24-26, 1990) describe a process based on a with titanium partially stabilized ULC steel for fire coating systems. The carbon content should be between 15 and 25 ppm. The titanium content is adjusted to the nitrogen and sulfur contents with 48/14 N <Ti <48 (N / 14 + S / 32). The aim is the complete setting of the nitrogen in titanium nitrides, although a small amount of carbon must remain in solution to ensure the bake-hardening effect. Generation in vacuum degassing plants is necessary. The advantage of this process is that the annealing annealing is no longer necessary, which makes it suitable for hot-dip coating systems. The bake-hardening parameters determined in the tensile test after 2% pre-stretching (BH 2 value) reach approximately 40 N / mm 2 for the steels produced in this way. The yield strengths are around 200 N / mm 2 , the values for the mean vertical anisotropy (r-value) are around 1.8.
Für die Darstellung solcher mit Titan teilstabilisierten ULC-Stähle liegen nach W. Bleck, R. Bode, O. Maid, L. Meyer: "Metallurgical Design of High-Strength ULC Steels" , Proc. of the Symp. on High-Strength Sheet Steεls f,or the Automotive Industry, Baltimore, October 16-19, 1994) die Titangehalte zwischen dem 0,6- und 3,4-fachen des Stickstoffgehaltes. Der Gesamtgehalt an Kohlenstoff und Stickstoff soll 50 ppm nicht über¬ schreiten. Die EP 0 620 288 AI offenbart ein Verfahren zur Her¬ stellung eines nur kaltgewalzten oder feuerbeschichteten kaltgewalzten Stahlbandes in kontinuierlichen Bandan¬ lagen, daε neben der Alterungsbeständigkeit hohe Bake- hardening Eigenschaften und aufgrund hoher r-Werte gute Tiefzieheigenschaften besitzt. Hierbei wird ein ULC-Stahl selbst oder ein ULC-Stahl mit entweder einer Titan- oder einer Nioblegierung oberhalb der Ac3-Umwandlungstempe- ratur, d.h. im Austenitgebiet, geglüht. Die Bake-harde¬ ning Werte erreichen bei diesem Verfahren 100 N/mm2. Eine Überalterungsglühung ist nicht notwendig. Alε ULC-Stahl muß die Stahlherstellung in einer Vakuumentgasungsanlage erfolgen. Schwierigkeiten hinsichtlich der Bandebenheit bereiten bei diesem Verfahren die notwendigen hohen Glühtemperaturen. Eine großtechnische Anwendung dieses Verfahrenε iεt nicht bekannt.According to W. Bleck, R. Bode, O. Maid, L. Meyer: "Metallurgical Design of High-Strength ULC Steels", Proc. of the Symp. on High-Strength Sheet Steεls f, or the Automotive Industry, Baltimore, October 16-19, 1994) the titanium content between 0.6 and 3.4 times the nitrogen content. The total content of carbon and nitrogen should not exceed 50 ppm. EP 0 620 288 A1 discloses a process for producing only cold-rolled or fire-coated cold-rolled steel strip in continuous strip lines, which, in addition to being resistant to aging, has high bake hardening properties and good deep-drawing properties due to high r values. Here, a ULC steel itself or a ULC steel with either a titanium or a niobium alloy is annealed above the Ac 3 conversion temperature, ie in the austenite area. With this method, the bake-harding values reach 100 N / mm 2 . An aging glow is not necessary. As ULC steel, the steel production must take place in a vacuum degassing plant. Difficulties with regard to strip flatness are caused by the necessary high annealing temperatures. A large-scale application of this method is not known.
In Bleck et al . a.a.O. wird darauf hingewiesen, daß die Erzeugung eines alterungsbeεtändigen Stahleε mit guten Umformeigenεchaften auf Baεiε unlegierter LC-Stähle in kontinuierlichen Bandanlagen ohne eine Überalterung nicht möglich ist. Da der Abkühlprozeß in gängigen Feuerbe¬ schichtungsanlagen aufgrund der Schmelztaucheinrichtung eingeschränkt iεt, kann hier eine Überalterungsglühung in Linie, wie oben erwähnt, nicht stattfinden. Die Erzeugung alterungsbeständiger Stähle mit Bake-hardening-Eigen- schaften in Feuerbeschichtungsanlagen beschränkt εich daher nach bisherigem Stand der Technik ausschließlich auf ULC-Stähle. Somit beinhalten bisher angewendete oder in der Literatur beschriebene Verfahren zur Herstellung von gut umformbarem Kaltfeinblech mit Bake-hardening- -Eigenschaften in kontinuierlichen Bandanlagen entweder die oben beschriebene zusätzliche Gühbehandlung für den Fall der Verwendung eines weichen unlegierten AI-beruhig¬ ten Tiefziehstahles, was eine Erzeugung in einer gängigen Feuerbeschichtungsanlage nicht erlaubt, oder eε müssen die aufwendiger herzustellenden ULC-Stähle mit sehr geringen Kohlenstoffgehalten verwendet werden. Die oben beschriebenen Verfahren auf Baεiε der ULC-Stähle umfassen hauptsächlich Stähle mit Streckgrenzen im unteren Bereich bis 240 N/mm2. Aufgrund der hohen mittleren r-Werte (> 1,5) eignen sie sich für Preßteile mit hohem Tief¬ ziehanteil .In Bleck et al. As mentioned above, it is pointed out that the production of an aging-resistant steel with good forming properties based on unalloyed LC steels in continuous belt systems is not possible without aging. Since the cooling process in conventional fire-coating systems is restricted due to the hot-dip device, an aging annealing in line, as mentioned above, cannot take place here. The production of aging-resistant steels with bake-hardening properties in hot-dip coating systems is therefore restricted to ULC steels according to the current state of the art. Thus, processes previously used or described in the literature for the production of readily deformable cold thin sheet with bake-hardening properties in continuous strip systems either include the additional annealing treatment described above for the case of using a soft, unalloyed, AI-soaked deep-drawing steel, which results in production not allowed in a common fire coating system, or must the more complex to produce ULC steels with very low carbon contents can be used. The above-described methods based on ULC steels mainly include steels with yield strengths in the lower range up to 240 N / mm 2 . Because of the high average r values (> 1.5), they are suitable for pressed parts with a high proportion of deep-drawn parts.
Darauε leitet εich die Aufgabe ab, ein gut umformbares höherfestes kaltgewalztes Stahlblech oder -band in einer kontinuierlichen Bandanlage ohne eine nachfolgende Über¬ alterungsglühbehandlung alterungsbeεtändig herzustellen, daε außerdem gute Bake-hardening-Eigenschaften besitzt. Die Kombination der hohen Werkstoffgrundfestigkeit und dem Bake-hardening Potential soll zu ausgezeichneten Beulsteifigkeiten der Preßteile führen.The task derived from this is to produce a readily deformable, high-strength cold-rolled steel sheet or strip in a continuous strip line without a subsequent aging annealing treatment, which also has good bake-hardening properties. The combination of the high basic material strength and the bake-hardening potential should lead to excellent buckling stiffness of the pressed parts.
Zur Lösung dieser Aufgabe wird ein Verfahren zur Erzeugung eines kaltgewalzten Stahlbleches oder -bandes mit guter Umformbarkeit, insbesondere Streckziehbarkeit zur Herstellung von Preßteilen mit hoher Beulsteifigkeit auε einem Stahl folgender Zuεammensetzung (in Maεεe-%) :To solve this problem, a method for producing a cold-rolled steel sheet or strip with good formability, in particular stretch-pullability for producing pressed parts with high buckling stiffness from a steel having the following composition (in mass%):
0, 01-0, 08 % C0, 01-0, 08% C
0, 10-0,80 % Mn max. 0,60 % Si0, 10-0.80% Mn max. 0.60% Si
0, 015-0,08 % AI max. 0, 005 % N0.015-0.08% AI max. 0.005% N
0,01-0,04 % jeweils Ti und/oder Nb, deren über die zur stöchiometrischen Abbindung des Stickstoffs notwendige Menge hinausgehender Gehalt im Bereich von -0,003 bis 0,015 % Ti bzw. 0,0015 bis 0,008 % Nb liegt, max. 0,15 % von insgesamt eines oder mehrerer0.01-0.04% each of Ti and / or Nb, the content of which exceeds the amount required for the stoichiometric setting of nitrogen in the range from -0.003 to 0.015% Ti or 0.0015 to 0.008% Nb, max. 0.15% of a total of one or more
Elemente aus der Gruppe Kupfer, Vanadium, Nickel,Elements from the group copper, vanadium, nickel,
Rest Eisen und unvermeidbare Verunreinigungen einschließlich max. 0,08 % P und max. 0,02 % S, vorgeschlagen, bestehend aus Vorwärmen der gegossenen Bramme auf eine Temperatur oberhalb von 1050 °C, Warmwalzen mit einer Endtemperatur im Bereich von über der Ar3-Temperatur biε 950 °C, vorzugsweise im Bereich von 870 biε 950 °C, Haspeln deε warmgewalzten Bandes auf eine Temperatur im Bereich von 550 bis 750 °C, Kaltwalzen mit einem Gesamt-Kaltwalzgrad von 40 bis 85 %, rekristallisierendeε Glühen deε Kaltbandes in einem Durchlaufofen bei einer Temperatur von mind. 720 °C mit anschließenden hohen Abkühlraten von 5 bis 70 K/s und abschließendem Dressieren.Balance iron and unavoidable impurities including max. 0.08% P and max. 0.02% S, proposed, consisting of preheating the cast slab to a temperature above 1050 ° C, hot rolling with a final temperature in the range from above the Ar 3 temperature to 950 ° C, preferably in the range from 870 to 950 ° C, reeling the hot-rolled strip a temperature in the range of 550 to 750 ° C, cold rolling with a total cold rolling degree of 40 to 85%, recrystallizing annealing of the cold strip in a continuous furnace at a temperature of at least 720 ° C with subsequent high cooling rates of 5 to 70 K / s and final skin training.
Seine Alterungsbeständigkeit erreicht der Stahl durch eine auf den Stickεtoffgehalt abgestimmte Titanzugabe. Diese führt zu einer frühzeitigen vollständigen Abbindung des Stickstoffs, der als ein die Alterungsbeständigkeit stark beeinträchtigendes Element bekannt iεt. In den Alterungsuntersuchungen (siehe nachfolgende Beispiele) wurde festgestellt, daß eine ausreichende Alterungsbe¬ ständigkeit dann beεteht, wenn eine über die zur Stickstoffabbindung hinausgehende Menge an Titan vorhanden ist, εo daß die Bildung einer Mindeεtmenge an Titankarbiden gewährleistet ist. Der Volumenanteil und die Zahl an Titankarbiden dürfen jedoch keinesfalls zu hoch sein, damit der Stahl die für den hohen Umform¬ anspruch notwendige Verfestigungscharakteristik und ausreichende Dehnungs- und Zähigkeitseigenschaften beεitzt. Daher sollte die Menge des nicht an Stickstoff gebundenen Nitridbildners 0,003 bis 0,015 % Ti bzw. 0,0015 biε 0,008 % Nb liegen. Diese Begrenzung der Nitridbildnermenge gewährleistet gleichmäßige mechanische Eigenschaften, die gegenüber prozeßbedingten Schwankungen in der Warmbandtemperaturführung (Beeinflussung der Ausscheidungsverteilung) weitgehend invariant sind. Bei Anwendung dieses Analysenkonzeptes ist sicherge¬ stellt, daß nach Abkühlung von Rekristallisations¬ temperatur genügend Kohlenstoff in gelöster Form vorhanden ist, damit gute Bake-hardening Eigenschaften vorliegen.The steel achieves its aging resistance by adding titanium to the nitrogen content. This leads to an early complete setting of the nitrogen, which is known to be an element which has a severe adverse effect on aging resistance. In the aging studies (see examples below) it was found that there is sufficient aging resistance if there is an amount of titanium in excess of the nitrogen setting, so that the formation of a minimum amount of titanium carbides is ensured. The volume fraction and the number of titanium carbides must not be too high, however, so that the steel has the hardening characteristics necessary for the high forming demands and sufficient elongation and toughness properties. Therefore, the amount of the nitride former not bound to nitrogen should be 0.003 to 0.015% Ti or 0.0015 to 0.008% Nb. This limitation of the amount of nitride former ensures uniform mechanical properties which are largely invariant compared to process-related fluctuations in the hot strip temperature control (influencing the precipitation distribution). When this analysis concept is used, it is ensured that, after the recrystallization temperature has cooled, sufficient carbon is present in dissolved form so that good bake-hardening properties are present.
Mit oder anstelle von Titan als Mikrolegierungselement kann auch Niob zur Nitrid- und Karbidbildung eingesetzt werden.With or instead of titanium as a microalloying element, niobium can also be used to form nitride and carbide.
Der Siliziumgehalt sollte für feuerverzinktes Feinblech vorzugsweise auf max. 0,15 % begrenzt sein.For hot-dip galvanized sheet, the silicon content should preferably be max. 0.15% may be limited.
Der wirtschaftliche Vorteil des erfindungsgemäßen Ver¬ fahrens beεteht darin, daß der zuεätzliche Prozeßschritt der Überalterungsglühung zum Erreichen der Alterungsbe¬ ständigkeit entfällt, obwohl die Stahlzusammenεetzung auf Basis der Analyse weicher unlegierter AI-beruhigter (LC)- Stähle beruht. Die Stahlerzeugung kann aufgrund dieses Analysenkonzeptes ohne aufwendige metallurgische Erzeu- gungεverfahren erfolgen. Außerdem werden Titan oder Niob nur in geringen Mengen benötigt, so daß der Stahl auch hinsichtlich der Legierungεzugaben kostengünstig zu erzeugen ist.The economic advantage of the method according to the invention consists in the fact that the additional process step of the aging annealing to achieve the aging resistance is eliminated, although the steel composition is based on the analysis of soft, unalloyed Al-alloyed (LC) steels. On the basis of this analysis concept, steel production can take place without complex metallurgical production processes. In addition, titanium or niobium are only required in small quantities, so that the steel can also be produced inexpensively with regard to the addition of alloys.
Das Herstellungsverfahren des Stahls umfaßt dasThe steel manufacturing process includes this
Vorwärmen der gegossenen Bramme auf eine Temperatur oberhalb von 1050 °C,Preheating the cast slab to a temperature above 1050 ° C,
Warmwalzen mit einer Endtemperatur im Bereich vonHot rolling with a final temperature in the range of
> Ar3 bis 950 °C,> Ar 3 to 950 ° C,
Haspeln des warmgewalzten Bandes im Temperaturbereich von 550 bis 750 °C,Coiling the hot-rolled strip in the temperature range from 550 to 750 ° C,
Kaltwalzen mit einem Gesamtverformungsgrad vonCold rolling with a total degree of deformation of
40 bis 85%, - 8 -40 to 85%, - 8th -
Rekriεtallisierende Glühen des Kaltbandes bei mindestens 720 °C in einem Durchlaufofen Abkühlen mit Abkühlraten von 5 biε 70 K/ε und Dressieren.Recrystallizing annealing of the cold strip at at least 720 ° C in a continuous furnace, cooling with cooling rates of 5 to 70 K / ε and skin passaging.
Bevorzugt soll das Kaltband mit einer Geschwindigkeit im Bereich von 5 bis 10 K/s auf die Temperatur der Rekri- εtalliεationεglühung erhitzt werden. Das rekristalli¬ sierende Glühen kann bevorzugt in Linie mit einer Feuerverzinkungsanlage vorgenommen werden.The cold strip should preferably be heated to the temperature of the recrystallization annealing at a speed in the range from 5 to 10 K / s. The recrystallizing annealing can preferably be carried out in line with a hot-dip galvanizing plant.
Die nach dem erfindungsgemaßen Verfahren hergeεtellten Stahlbänder oder -bleche zeichnen sich durch eine hohe Ausgangεstreckgrenze (größer 240 N/mm2) und ein hohes Verfeεtigungsvermögen im Bereich kleiner plastiεcher Dehnungen aus . Zusammen mit niedrigen Werten der senkrechten Anisotropie, die ein bevorzugtes Fließen aus der Dicke kennzeichnen, sind Preßteile mit hohem Streck¬ ziehanteil, z.B. Automobilaußenhautteile, der ideale Anwendungsbereich. Die starke Verfestigung dieses Werkstoffeε, die schon bei kleinen plastischen Verformungen auftritt und εich in εehr hohen Work- hardening-Werten äußert, iεt ein wesentlicher Punkt für die Eigenschaften des Produktes. Die starke Verfestigung begünstigt die Kraftübertragung auf benachbarte Werk- εtoffbereiche, wodurch ein lokaleε frühzeitiges Material¬ versagen, z.B. Einschnürung, vermieden wird. Der Werk¬ stoff kann somit über die gesamte Preßteilfläche gleich¬ mäßiger fließen. Zusätzlich wirken εich die geringen Unterschiede der r-Werte in Abhängigkeit vom Winkel zur Walzrichtung günstig für ein gleichmäßiges Umformver¬ halten aus. Dieses isotrope Verhalten wird durch kleine Werte der planaren Anisotropie belegt. BeispieleThe steel strips or sheets produced by the process according to the invention are distinguished by a high initial yield strength (greater than 240 N / mm 2 ) and a high strengthening capacity in the range of small plastic expansions. Together with low values of the vertical anisotropy, which characterize a preferred flow from the thickness, pressed parts with a high proportion of drawn parts, for example automobile outer skin parts, are the ideal area of application. The strong solidification of this material, which occurs even with small plastic deformations and is expressed in very high work hardening values, is an essential point for the properties of the product. The strong solidification favors the transmission of force to neighboring material areas, as a result of which local material failure, eg constriction, is avoided. The material can thus flow more evenly over the entire surface of the pressed part. In addition, the slight differences in the r values as a function of the angle to the rolling direction have a favorable effect on uniform forming behavior. This isotropic behavior is evidenced by small values of the planar anisotropy. Examples
Die über Strangguß hergestellten Brammen der erfindungs¬ gemaß hergestellten Stähle A und B, deren chemische Zusammensetzungen in Tabelle l aufgeführt εind, wurden in einem Stoßofen auf Temperaturen von ca. 1200 °C wieder¬ erwärmt und auf Enddicken von 2,8-3,3 mm oberhalb der Ar3-Temperatur warmgewalzt. Die Endwalz- und Haspeltem¬ peraturen sind Tabelle 2 zu entnehmen. Für die Bänder der Stähle A und B wurden zwei Haspeltemperaturklassen ange¬ wendet: 730 °C (Stähle AI und Bl) und 600°C (Stähle A2 und B2) . Die Bänder wurden mit Verformungεgraden zwischen 65 und 75 % auf Dicken zwischen 0,8 und 1,0 mm kaltge¬ walzt und anschließend in einer Feuerbeschichtungsanlage erst rekristallisierend geglüht und danach feuerverzinkt. Die Bandtemperatur im Rekristalliεationsofen betrug 800 °C. Die Abkühlgeschwindigkeiten nach dem rekristal- liεierenden Glühen lagen zwiεchen 10 und 50 K/ε. Die verzinkten Bänder wurden mit 1,8 % dreεεiert und waren danach streckgrenzendehnungsfrei.The slabs of steels A and B produced according to the invention, the chemical compositions of which are listed in Table 1, were reheated to temperatures of approximately 1200 ° C. and to final thicknesses of 2.8-3.3 in a pusher furnace mm hot rolled above the Ar 3 temperature. The final rolling and coiling temperatures are shown in Table 2. Two reel temperature classes were used for the strips of steels A and B: 730 ° C (steels AI and Bl) and 600 ° C (steels A2 and B2). The strips were cold rolled with degrees of deformation between 65 and 75% to thicknesses between 0.8 and 1.0 mm and then first recrystallized in a hot-dip coating plant and then hot-dip galvanized. The strip temperature in the recrystallization furnace was 800 ° C. The cooling rates after the recrystallizing annealing were between 10 and 50 K / ε. The galvanized strips were tressed at 1.8% and were then free from elongation limit.
Tabellen 2 und 3 zeigen die im Zugversuch ermittelten mechanischen Eigenschaften und Korngrößen der Bänder A und B im Winkel von 90° zur Walzrichtung gemessen. Nur die r-Werte und die Werte für die planare Anisotropie berechnen εich wie folgt jeweils aus drei Zugproben, die in den Winkellagen 0°, 45° und 90° zur Walzrichtung entnommen wurdenTables 2 and 3 show the mechanical properties and grain sizes of strips A and B determined in the tensile test, measured at an angle of 90 ° to the rolling direction. Only the r values and the values for the planar anisotropy are calculated as follows from three tensile specimens, which were taken in the angular positions 0 °, 45 ° and 90 ° to the rolling direction
rm = (r0„ - 2 r450 + r90.) / 4 , Δr = (r0. - 2 r45. + r90„) / 2r m = (r 0 "- 2 r 450 + r 90" ) / 4, Δr = (r 0. - 2 r 45. + r 90 ") / 2
Der BH0-Wert entspricht dem Anstieg der unteren Streck¬ grenze nach einer Wärmebehandlung von 20 Minuten bei 170 °C. Die Größe WH gibt die Höhe der Verformungsver¬ festigung bei einer Reckung der Zugprobe um 2 % an. Sie wird berechnet, indem die Streckgrenze Rpc : von der gemessenen Spannung bei 2 % Verformung subtrahiert wird. Die Größe BH2 entspricht dem Anstieg der unteren Streckgrenze nach einer Wärmebehandlung von 20 Minuten bei 170 °C, gemessen an der 2 % vorgereckten Zugprobe.The BH 0 value corresponds to the increase in the lower yield point after a heat treatment of 20 minutes at 170 ° C. The size WH indicates the amount of deformation hardening when the tensile test is stretched by 2%. she is calculated by subtracting the yield strength Rp c: from the measured stress at 2% deformation. The size BH 2 corresponds to the increase in the lower yield strength after a heat treatment of 20 minutes at 170 ° C, measured on the 2% pre-stretched tensile test.
Die feuerverzinkten kaltgewalzten Bänder aus den Stählen A und B zeigen nach einer künstlichen Alterung von 60 Minuten bei 100 °C ein nahezu unverändertes Niveau der unteren oder oberen Streckgrenze (Tabelle 3) . Auch die Ausprägung der Streckgrenzendehnung bleibt unter 0,5 %, wodurch die Alterungsbeständigkeit für eine fließfi- gurenfreie Verarbeitung auch nach längeren Lagεrzeiten ausreichend ist. Der Verlauf des differentielien (momen¬ tanen) Verfestigungsexponentes (n-Wert) über der Gesamt¬ dehnung ist in Fig. 1 für den Stahl AI (Haspeltemperatur 730 °C) und in Fig. 2 für den Stahl A2 (Haεpeltemperatur 600 °C) aufgetragen. Die Maxima der differentielien n-Werte sind in Tabelle 2 jeweils aufgeführt; sie errei¬ chen bei den Stählen A und B für beide Haspeltemperatur- klaεεen mindeεtenε 0,170, bei den hohen Haspeltempera- turen sogar mindestens 0,180. Daε n-Wert-Maximum der Stähle A und B liegt im Bereich geringer Geεamtdehnungen zwiεchen 2 und 5 %. Die Streckgrenzen sind für die höhergehaspelten Varianten AI und Bl ca. 50 N/mm2 größer alε für die niedrig gehaspelten Varianten A2 und B2, so daß durch die Wahl der Haεpeltemperatur die Auεgangεlage der Streckgrenze festgelegt werden kann. Die Werte für die mittlere senkrechte Anisotropie sind für die erfin¬ dungsgemäßen Stähle AI, A2, Bl und B2 mit 1,0-1,1 gering. Unabhängig von der Haspeltemperatur besitzen sie isotrope Eigenschaften mit Δr-Werten zwischen 0 und 0,3. Bei Anwendung der hohen Haspeltemperaturen liegen die Work- hardening Werte, die ein Maß für die Verfestigung durch plastische Verformung darstellen, mit ca. 50 N/mm2 sehr hoch. Unabhängig von der Haspeltemperatur erreichen die Kenngrößen für daε Bake-hardening mit oder ohne Vorver¬ formung in allen Fällen mindestens 45 N/mm2. Der Streck¬ grenzenanstieg nach der Lackierbehandlung eines gepreßten Teileε kann durch die Summe WH+BH2 abgeεchätzt werden. Bei den hohen Haεpeltemperaturen (Stähle AI und Bl) liegen diese Werte mindeεtenε bei 100 N/mm2. Bei den niedrigeren Haεpeltemperaturen (Stähle A2 und B2) iεt die Summe WH+BH2 mit mindestens 60 N/mm2 immer noch günstig.The hot-dip galvanized cold-rolled strips made of steels A and B show an almost unchanged level of the lower or upper yield strength after artificial aging of 60 minutes at 100 ° C (Table 3). The extent of the yield point elongation also remains below 0.5%, which means that the aging resistance is sufficient for processing without flow figures, even after long periods of storage. The course of the differential (momentary) hardening exponent (n value) over the total elongation is in Fig. 1 for the steel AI (reel temperature 730 ° C) and in Fig. 2 for the steel A2 (coil temperature 600 ° C) applied. The maxima of the differential n values are listed in Table 2; They reach at least 0.170 for steels A and B for both reel temperature classes, and even at least 0.180 for high reel temperatures. The maximum n value of steels A and B is in the range of low total strains between 2 and 5%. The yield strengths are about 50 N / mm 2 larger for the higher-coiled variants AI and B1 than for the low-coiled variants A2 and B2, so that the starting position of the yield strength can be determined by the choice of the coiler temperature. The values for the mean vertical anisotropy for the steels AI, A2, B1 and B2 according to the invention are low at 1.0-1.1. Regardless of the reel temperature, they have isotropic properties with Δr values between 0 and 0.3. When using the high reel temperatures, the work hardening values, which represent a measure of the hardening by plastic deformation, are very high at approx. 50 N / mm 2 . Regardless of the reel temperature, the Characteristic values for bake-hardening with or without pre-deformation in all cases at least 45 N / mm 2 . The increase in yield strength after the painting treatment of a pressed part can be estimated by the sum WH + BH 2 . At the high coil temperatures (steels Al and B1), these values are at least 100 N / mm 2 . At the lower coil temperatures (steels A2 and B2) the sum WH + BH 2 with at least 60 N / mm 2 is still favorable.
In den Tabellen l, 2 und 3 εind zusätzlich Stähle C biε E zum Vergleich aufgeführt, die im Unterschied zu den Stählen A und B entweder kein Titan enthalten (Stahl E) oder Titangehalte besitzen, die bezogen auf den Stick¬ stoffgehalt unterstöchiometrisch liegen (Stähle C und D mit Ti/N < 3.4) . Die Werte des Ausgangεzuεtandes, d.h. nicht gealtert, beziehen sich auf den ausdressierten Zustand. Der Anstieg der unteren Streckgrenze (Rel) und der Streckgrenzendehnungen nach einer künstlichen Alterung sind bei diesen Vergleichsstählen deutlich höher als bei den erfindungsgemäß hergestellten Stählen A und B. Vor allem die obere Streckgrenze (Reh) nimmt biε zu 70 N/mm2 zu. Eine fehlerfreie Verarbeitung nach längerer Auslagerung iεt bei den Stählen C biε E nicht möglich.Tables 1, 2 and 3 additionally list steels C to E for comparison, which, in contrast to steels A and B, either contain no titanium (steel E) or have titanium contents which are substoichiometric in relation to the nitrogen content (steels C and D with Ti / N <3.4). The values of the initial state, ie not aged, relate to the extracted state. The increase in the lower yield strength (R el ) and the yield strength expansions after artificial aging are significantly higher for these comparative steels than for steels A and B produced according to the invention. Above all, the upper yield strength (deer) increases up to 70 N / mm 2 . Correct processing after long aging is not possible with steels C to E.
Der Stahl F enthält kein Titan εondern Niob. Aufgrund der Haspeltemperatur von 600°C und deε Legierenε mit Niob liegt seine Streckgrenze mit 350 N/mm2 sehr hoch. Der mittlere r-Wert beträgt 1,0 und der Δr-Wert liegt mit - 0,20 für ein gleichmäßiges Umformverhalten günstig. Wie die Stähle A und B, die mit Titan legiert sind, bleibt die untere und obere Streckgrenze bei dem Nb-legierten .Stahl- F ebenfallε stabil und die Streckgrenzendehnung unter 1 %, so daß auch hier eine fließlinienfreie Ver¬ arbeitung nach längeren Lagerzeiten des Werkstoffes möglich ist. Das Umformverhalten der erfindungsgemäß hergestellten Stähle AI und Bl wurde in einem praxisnahen Großversuch anhand von formgepreßten PKW-Motorhauben umfangreich untersucht . Es wurden bezüglich Formtreue und Oberfläche der Preßteile einwandfreie Abpreßergebniεεe erzielt, die auch bei der Verarbeitung nach einer Lagerzeit von 5 Monaten reproduzierbar waren. Steel F contains no titanium, but niobium. Due to the reel temperature of 600 ° C and the alloying with niobium, its yield strength is very high at 350 N / mm 2 . The mean r value is 1.0 and the Δr value is - 0.20, which is favorable for uniform forming behavior. Like steels A and B, which are alloyed with titanium, the lower and upper yield strength of the Nb-alloyed steel is also stable and the yield strength elongation is less than 1%, so that here too, processing without flow lines after longer storage times of the Material is possible. The forming behavior of the steels AI and Bl produced according to the invention was extensively investigated in a practical large-scale test using molded automobile bonnets. With regard to the shape accuracy and surface of the pressed parts, perfect pressing results were achieved, which were reproducible even after processing after a storage period of 5 months.
Tabelle 1Table 1
TabeUe 2TabeUe 2
Tabelle 3: Alterungseigenschaften, Work- und Bake-hardeniπg-Werte der uniersuchten StähleTable 3: Aging properties, work and bake hardening values of the steels searched for
Die Zugversuche wurden an Proben mit Meßlängen von 80mm durchgeführt.The tensile tests were carried out on samples with measuring lengths of 80 mm.
"ΔRel nach Alterung" gibt den Zuwachs der unteren Streckgrenze nach einer künstlichen Alterung der Zugproben (100°C, 60 Minuten) an."ΔRel after aging" indicates the increase in the lower yield strength after artificial aging of the tensile samples (100 ° C, 60 minutes).
"ΔReh nach Alterung" gibt den Zuwachs der oberen Streckgrenze nach einer künstlichen Alterung der Zugproben (100°C, 60 Minuten) an."ΔReh after aging" indicates the increase in the upper yield strength after artificial aging of the tensile samples (100 ° C, 60 minutes).
"ARe nach Alterung" gibt die Streckgrenzendehπung nach einer künstlichen Alterung der Zugproben (100°C, 60 Minuten) an."ARe after aging" indicates the elongation at break after artificial aging of the tensile specimens (100 ° C, 60 minutes).
"WH" gibt die Verformungsverfestigung (Work-hardening) nach 2% Reckung an."WH" indicates the work hardening after 2% stretching.
"rw" gibt das Maximum des differeπtiellen n-Wertes an."rw" indicates the maximum of the differential n value.
"εnmax" ist die Gesamtdehnung, bei der das Maximum des n-Wertes auftritt. "ε n max" is the total strain at which the maximum of the n value occurs.
9\ 9 \

Claims

Patentansprüche claims
1. Verfahren zur Erzeugung eines kaltgewalzten Stahlbleches oder -bandes mit guter Umformbarkeit, insbesondere Streckziehbarkeit zur Herstellung von Preßteilen mit hoher Beulsteifigkeit aus einem Stahl folgender Zusammensetzung (in Masse-%):1. Process for producing a cold-rolled steel sheet or strip with good formability, in particular stretchability for producing pressed parts with high buckling stiffness from a steel of the following composition (in% by mass):
0,01 bis 0,08 % C 0,10- bis 0,80 % Mn max. 0,60 % Si 0,015 bis 0,08 % AI max. 0,005 % N 0,01 bis 0,04 % jeweils Ti und/oder Nb mit der Maßgabe, daß der über die zur stöchiometrischen Abbindung von Stickstoff notwendige Menge hinausgehende Gehalt im Bereich von 0,003 bis 0,015 % Ti bzw. 0,0015 bis 0,008 % Nb liegt, ferner max. 0,15 % insgesamt eines oder mehrerer Elemente aus der Gruppe Kupfer, Vanadium, Nickel, Rest Eisen und unvermeidbare Verunreinigungen, einschließlich max. 0,08 % P, max. 0,02 % S,0.01 to 0.08% C 0.10 to 0.80% Mn max. 0.60% Si 0.015 to 0.08% AI max. 0.005% N 0.01 to 0.04% each of Ti and / or Nb with the proviso that the content in excess of the amount required for the stoichiometric setting of nitrogen is in the range of 0.003 to 0.015% Ti or 0.0015 to 0.008% Nb lies, furthermore max. 0.15% in total of one or more elements from the group of copper, vanadium, nickel, remainder iron and unavoidable impurities, including max. 0.08% P, max. 0.02% S,
bestehend aus Vorwärmen der gegossenen Bramme auf eine Temperatur oberhalb von 1050 °C, Warmwalzen mit einer Endtemperatur im Bereich von oberhalb Ar3 bis 950 °C, Haspeln des warmgewalzten Bandes bei einer Temperatur im Bereich von 550 bis 750 °C, Kaltwalzen mit einem Gesamtverformungs- grad von 40 bis 85 %, rekristallisierendes Glühen des Kaltbandes bei einer Temperatur von mind. 720 "c in einem Durchlaufofen, Abkühlen mit Abkühlraten von 5 bis 70 K/s und abschließendem Dressieren. consisting of preheating the cast slab to a temperature above 1050 ° C, hot rolling with a final temperature in the range from above Ar 3 to 950 ° C, coiling of the hot-rolled strip at a temperature in the range from 550 to 750 ° C, cold rolling with a total deformation - Degree of 40 to 85%, recrystallizing annealing of the cold strip at a temperature of at least 720 "c in a continuous furnace, cooling with cooling rates of 5 to 70 K / s and final skin-pass.
2. Verfahren nach Anspruch l, d a d u r c h g e k e n n z e i c h n e t, daß das Kaltband mit einer Geschwindigkeit im Bereich von 5 bis 10 K/s auf die Temperatur der Rekristallisationsglühung erhitzt wird.2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the cold strip is heated to the temperature of the recrystallization annealing at a rate in the range of 5 to 10 K / s.
3. Verfahren nach einem der Ansprüche 1 oder 2, d a d u r c h g e k e n n z e i c h n e t, daß das rekristallisierende Glühen des kaltgewalzten Bandes in Linie mit einer Feuerverzinkungsanlage vorgenommen wird.3. The method according to any one of claims 1 or 2, that the recrystallizing annealing of the cold-rolled strip is carried out in line with a hot-dip galvanizing plant.
4. Verfahren nach Anspruch 3, bei dem der Silizium¬ gehalt auf max. 0,15 % begrenzt wird.4. The method according to claim 3, wherein the silicon content to max. 0.15% is limited.
5. Verfahren nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, daß das Endwalzen bei einer Temperatur im Bereich von 870 bis 950 °C erfolgt. 5. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the final rolling is carried out at a temperature in the range of 870 to 950 ° C.
EP97922915A 1996-06-01 1997-04-26 Process for producing an easily shaped cold-rolled sheet or strip Expired - Lifetime EP0914480B1 (en)

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DE19622164A DE19622164C1 (en) 1996-06-01 1996-06-01 Cold rolled steel sheet with good drawing properties
PCT/EP1997/002169 WO1997046720A1 (en) 1996-06-01 1997-04-26 Process for producing an easily shaped cold-rolled sheet or strip

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112131528A (en) * 2020-09-10 2020-12-25 东北大学 Tension distribution setting method for steel strip in asynchronous cold continuous rolling process

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19740148C1 (en) * 1997-09-12 1999-07-15 Thyssenkrupp Stahl Ag Process for the manufacture of dent-resistant enamelled components made of age-sensitive steel
FR2795743B1 (en) * 1999-07-01 2001-08-03 Lorraine Laminage LOW ALUMINUM STEEL SHEET FOR PACKAGING
FR2795741B1 (en) * 1999-07-01 2001-08-03 Lorraine Laminage CALM LOW-CARBON STEEL SHEET WITH ALUMINUM FOR PACKAGING
FR2795742B1 (en) 1999-07-01 2001-08-03 Lorraine Laminage CALM ALUMINUM CARBON STEEL SHEET FOR PACKAGING
FR2795740B1 (en) * 1999-07-01 2001-08-03 Lorraine Laminage CALM LOW-CARBON STEEL SHEET WITH ALUMINUM FOR PACKAGING
DE10020118B4 (en) * 2000-04-22 2009-11-12 Schaeffler Kg Method for verifying sealability of selected exhaust valve of selected cylinder in internal combustion engine in motor vehicle, involves concluding sealability of valve based on measured values of lambda sensor in one of exhaust gas strands
DE10102932C1 (en) * 2001-01-23 2002-08-22 Salzgitter Ag Process for producing a cold-rolled steel strip or sheet and strip or sheet which can be produced by the process
FR2820150B1 (en) * 2001-01-26 2003-03-28 Usinor HIGH STRENGTH ISOTROPIC STEEL, METHOD FOR MANUFACTURING SHEETS AND SHEETS OBTAINED
US6635127B2 (en) * 2001-08-02 2003-10-21 Illinois Tool Works Inc. Steel strapping and method of making
SE526120C2 (en) * 2002-03-13 2005-07-05 Avestapolarit Ab Process for the manufacture of an ultra-high-strength stretched or stretched product of steel
FR2845694B1 (en) * 2002-10-14 2005-12-30 Usinor METHOD FOR MANUFACTURING COOK-CURABLE STEEL SHEETS, STEEL SHEETS AND PIECES THUS OBTAINED
KR20060028909A (en) * 2004-09-30 2006-04-04 주식회사 포스코 High strength cold rolled steel sheet excellent in shape freezability,and manufacturing method thereof
DE102005058658A1 (en) * 2005-12-07 2007-06-14 Kermi Gmbh Method for reducing the wall thickness of steel radiators
CN103108964B (en) 2010-08-31 2015-06-17 塔塔钢铁艾默伊登有限责任公司 Method for hot forming a coated metal part and formed part
UA109963C2 (en) * 2011-09-06 2015-10-26 CATHANE STEEL, APPROVING CONSEQUENCES OF SEPARATION OF PARTS AFTER HOT FORMING AND / OR CUTTING IN TOOL, THAT HAS A HIGHER MACHINE
JP5618431B2 (en) 2013-01-31 2014-11-05 日新製鋼株式会社 Cold rolled steel sheet and method for producing the same
WO2014145536A1 (en) * 2013-03-15 2014-09-18 Am/Ns Calvert Llc New high strength bake hardenable low alloy steel and process for manufacture thereof
CN103276172B (en) * 2013-05-14 2015-01-21 武汉钢铁(集团)公司 Energy-saving rolling method of low alloy steel based on critical temperature
EP3204530B1 (en) * 2014-10-09 2019-01-09 ThyssenKrupp Steel Europe AG Cold rolled steel sheet and recrystallisation-annealed steel flat product and method for producing the same
US11453923B2 (en) 2016-09-20 2022-09-27 Thyssenkrupp Steel Europe Ag Method for manufacturing flat steel products and flat steel product
CN112853212B (en) * 2021-01-05 2022-06-07 广西柳钢华创科技研发有限公司 Low-cost cold-rolled high-strength steel for tool cabinets

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5246323A (en) * 1975-10-10 1977-04-13 Nisshin Steel Co Ltd Process for producing cold rolled high tensile strength steel plate ha ving excellent flange pressed drawability
DE3803064C2 (en) * 1988-01-29 1995-04-20 Preussag Stahl Ag Cold rolled sheet or strip and process for its manufacture
EP0620288B1 (en) * 1992-08-31 2000-11-22 Nippon Steel Corporation Cold-rolled sheet and hot-galvanized cold-rolled sheet, both excellent in bake hardening, cold nonaging and forming properties, and process for producing the same
DE19547181C1 (en) * 1995-12-16 1996-10-10 Krupp Ag Hoesch Krupp Mfg. cold-rolled, high strength steel strip with good shapability

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9746720A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112131528A (en) * 2020-09-10 2020-12-25 东北大学 Tension distribution setting method for steel strip in asynchronous cold continuous rolling process
CN112131528B (en) * 2020-09-10 2023-08-04 东北大学 Tension distribution setting method for asynchronous cold continuous rolling process of steel strip

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