EP0216044A2 - Process for manufacturing non-aging steel strip having a high cold formability - Google Patents
Process for manufacturing non-aging steel strip having a high cold formability Download PDFInfo
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- EP0216044A2 EP0216044A2 EP86109521A EP86109521A EP0216044A2 EP 0216044 A2 EP0216044 A2 EP 0216044A2 EP 86109521 A EP86109521 A EP 86109521A EP 86109521 A EP86109521 A EP 86109521A EP 0216044 A2 EP0216044 A2 EP 0216044A2
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 28
- 239000010959 steel Substances 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 26
- 230000032683 aging Effects 0.000 title claims description 7
- 238000004519 manufacturing process Methods 0.000 title description 12
- 238000005098 hot rolling Methods 0.000 claims abstract description 9
- 238000000137 annealing Methods 0.000 claims abstract description 8
- 238000005096 rolling process Methods 0.000 claims abstract description 8
- 238000005097 cold rolling Methods 0.000 claims abstract description 5
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract 4
- 229910052782 aluminium Inorganic materials 0.000 claims abstract 3
- 229910052796 boron Inorganic materials 0.000 claims abstract 3
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract 3
- 229910052719 titanium Inorganic materials 0.000 claims abstract 3
- 229910052720 vanadium Inorganic materials 0.000 claims abstract 3
- 229910052742 iron Inorganic materials 0.000 claims abstract 2
- 229910052758 niobium Inorganic materials 0.000 claims abstract 2
- 239000010960 cold rolled steel Substances 0.000 claims description 5
- 239000000155 melt Substances 0.000 claims description 2
- 238000005496 tempering Methods 0.000 claims 2
- 239000011248 coating agent Substances 0.000 claims 1
- 238000000576 coating method Methods 0.000 claims 1
- 238000011109 contamination Methods 0.000 claims 1
- 238000002844 melting Methods 0.000 claims 1
- 230000008018 melting Effects 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 10
- 238000010924 continuous production Methods 0.000 abstract description 4
- 238000003723 Smelting Methods 0.000 abstract 1
- 239000012535 impurity Substances 0.000 abstract 1
- 238000011068 loading method Methods 0.000 abstract 1
- 229910052698 phosphorus Inorganic materials 0.000 abstract 1
- 230000002349 favourable effect Effects 0.000 description 3
- 230000035882 stress Effects 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000011437 continuous method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Images
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
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/041—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing involving a particular fabrication or treatment of ingot or slab
Definitions
- the invention relates to a method for producing an aging-resistant steel strip with high cold formability by hot strip rolling, cold rolling, recrystallizing annealing and subsequent skin passaging.
- Cold rolled steel strip is widely used for the production of cold formed products.
- different properties characteristic values
- different properties characteristic values
- the following material properties and characteristic values are also decisive: - When bending, such as in the production of cold profiles, low yield strengths and high elongation at break values are sufficient, - in the case of stretch-drawing processes, a high hardening exponent n m is also sought, -
- the value of the vertical anisotropy r m should also be as high as possible.
- Hot rolled steels for the aforementioned purposes are recrystallized annealed after cold rolling.
- Discontinuous annealing processes have disadvantages, eg low productivity, because the process takes several days.
- the newly preferred continuous processes of recrystallizing annealing such as those shown in the book "Manufacture of Cold-Rolled Strip", 1970, published by Stahleisen Düsseldorf in Fig. 28, offer the possibility of achieving significantly higher productivity in this one process step.
- OS 2 348 062 describes the use of these devices for producing cold-rolled steel strip with good forming properties from unsettled and calmed steels.
- the steel is subjected to a brief aging treatment in the range from about 250 to 450 ° C. after the annealing treatment in order to achieve the aging resistance required for processing the cold strip. This is followed by the so-called "skin treatment".
- the object of the invention is achieved in detail in that the high slab preheating temperatures used in the prior art are exited in the new process, that is to say are lowered.
- the final rolling temperature is also differentiated, that is, the hot rolling is ended at a temperature below or above the transition temperature A 3 in the last finishing stand.
- the overall effect is surprisingly achieved in a product whose properties are specifically improved.
- a temperature range of approximately 1 100-1 300 ° C is generally introduced ("Eisendazzling", Berlin 1961, p. 427).
- the higher ranges are preferred because, as is known, the hot-formability of the steels is improved with increasing temperature, so that the energy consumption of the rolling motors can be reduced as the initial rolling temperature increases, and also - despite the inevitable drop in temperature from the roughing stand to the last finishing stand - the final roll temperature is still above the structural transformation temperature A3. It is considered advantageous that the last frame of the finishing line is passed above A3.
- DE-OS 31 38 302 claim 1, describes a process for producing "cold-rolled steel strip of high strength".
- a heating of the steel slabs to a maximum of 1200 ° C or in the range 1200 to 1000 ° C is also proposed.
- the desired yield strengths are, as Table 2 shows, over 20 kp / mm2.
- This publication does not provide any references to the steels to be produced according to the invention, which have a completely different composition, their forming behavior and low yield strengths.
- Claims 1 and 5 name the upper and lower limits of the slab preheating temperature according to the invention.
- Claim 6 specifies (compared to the prior art) lower roll temperatures. The effect of this measure is explained in Fig. 1 using bar graphs. Steel 1 has the following composition (percentages by mass): C 0.02% Si 0.01% Mn 0.2% P 0.008% S 0.012% Al 0.04% N 0.003%
- This Al-calmed steel has a low alloy content and does not belong to the group of "micro-alloyed steels". It was preheated as a slab according to the prior art at 1 270 ° C and rolled in a conventional manner warm with a final temperature of 920 ° C and cold. The most important five material key figures are graphically recorded on the left edge of the diagrams. The yield strength is still sufficient for high cold forming requirements; At 40%, the elongation at break is barely sufficient for very demanding applications. The same applies to the hardening coefficient. The same characteristic values are shown in the right half of the corresponding fields when the cold strip is produced according to the invention.
- the slab was first preheated to the lowest temperature range mentioned in claim 5 and then, as is known to the person skilled in the art, the strip was cooled between the preliminary and the finished batch, so that the strip emerged from the last finishing stand at 800 ° C.
- the percentage decrease in thickness of the strip after passing through the transition temperature still reached 40%.
- Cold strip made from this hot strip despite the low alloying effort, achieved such favorable values of yield strength, elongation at break and strengthening exponent that these products can also be used for the most demanding purposes using stretch drawing and three-dimensional folding.
- the characteristic value of the vertical anisotropy r m with 1.3 is not sufficient for the production of complicated deep-drawn parts.
- Claim 7 specifies for the hot rolling process that the entire rolling process is ended (that is, the last finishing stand is run through) before the rolling stock cools below the A3 point.
- steels according to the invention for example 2 the same low-alloy steel is used, which was also produced according to example 1 and subsequently examined.
- the analysis according to the invention is in percentages by mass: C 0.005% Si 0.01% Mn 0.18% P 0.006% S 0.014% Al 0.03% N 0.004% Ti 0.09%
- This steel was produced in the steelworks more elaborately, namely vacuum decarburized and also alloyed with Ti.
- Example 2 As shown in Fig. 1 in the corresponding columns, it can be seen in Example 2 that the left bars, which represent the state of the art, with a slab preheating temperature of 1 270 and a roll end temperature of 920 ° C, do not have any key figures for maximum cold formability: the proof stress with 190 N / mm2, the elongation at break with 40% and the hardening exponent with 0.22 are not yet optimal.
- the values of the strip produced according to the invention are considerably more favorable: despite its scarce alloy: lower yield strength with 160 N / mm2; significantly higher elongation at break and better fastening exponent as a result of the low slab preheating temperature and the final roll temperature of 920 ° C.
- Example 3 the material characteristics shown in Example 3 are less favorable in the manufacturing process according to the prior art; in contrast, they are significantly improved by the manufacturing process according to the invention.
- Claim 8 relates to the use of the method according to the invention using the continuous strip drawing yards known per se.
- Claims 9 and 10 relate to the connection of the manufacturing method according to the invention with a known aging treatment or with the application of a metallic protective coating in the melt flow.
- the combination according to the invention of the process steps mentioned leads to the fact that cold-rolled strip steels can be produced more reliably with improved productivity and with improved cold formability for specific purposes.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Herstellen eines alterungsbeständigen Bandstahles mit hoher Kaltumformbarkeit durch Warmbandwalzen, Kaltwalzen, rekristallisierendes Glühen und nachfolgendes Dressieren.The invention relates to a method for producing an aging-resistant steel strip with high cold formability by hot strip rolling, cold rolling, recrystallizing annealing and subsequent skin passaging.
Kaltgewalzter Bandstahl wird vielfach zur Herstellung von kaltumgeformten Erzeugnissen verwendet. Je nach Art des Umformverfahrens sind unterschiedliche Eigenschaften (Kennwerte) erforderlich; in allen Fällen hoher Verformung sind niedrige Dehngrenzen und hohe Bruchdehnungswerte vorteilhaft. Außerdem sind folgende Werkstoffeigenschaften bzw. Kennwerte maßgebend:
- Beim Abkanten, wie beispielsweise bei der Herstellung von Kaltprofilen, sind niedrige Dehngrenzen und hohe Bruchdehnungswerte ausreichend,
- bei Streckziehvorgängen wird zusätzlich ein hoher Verfestigungsexponent nm angestrebt,
- bei Tiefziehhbeanspruchung, speziell zur Herstellung komplizierter Teile z.B. von Automobilkarrosserien, sollte zusätzlich der Wert der senkrechten Anisotropie rm möglichst hoch sein.Cold rolled steel strip is widely used for the production of cold formed products. Depending on the type of forming process, different properties (characteristic values) are required; in all cases of high deformation, low yield strengths and high elongation at break values are advantageous. The following material properties and characteristic values are also decisive:
- When bending, such as in the production of cold profiles, low yield strengths and high elongation at break values are sufficient,
- in the case of stretch-drawing processes, a high hardening exponent n m is also sought,
- In the case of deep drawing stress, especially for the production of complicated parts, for example of automobile bodies, the value of the vertical anisotropy r m should also be as high as possible.
Warmgewalzte Stähle für die vorgenannten Zwecke werden nach dem Kaltwalzen rekristallisierend geglüht. Diskontinuierliche Glühverfahren weisen Nachteile, z.B. geringe Produktivität auf, weil die Durchführung mehrere Tage benötigt. Die neuerlich bevorzugten kontinuierlichen Verfahren des rekristallisierenden Glühens, wie sie z.B. in dem Buch "Herstellung von kaltgewalztem Band", 1970, Verlag Stahleisen Düsseldorf in Bild 28 gezeigt sind, bieten bei diesem einen Verfahrensschritt die Möglichkeit zur Erreichung deutlich höherer Produktivität. Die OS 2 348 062 beschreibt die Verwendung dieser Vorrichtungen zur Erzeugung kaltgewalzten Stahlbandes mit guten Umformeigenschaften aus unberuhigten und beruhigten Stählen.Hot rolled steels for the aforementioned purposes are recrystallized annealed after cold rolling. Discontinuous annealing processes have disadvantages, eg low productivity, because the process takes several days. The newly preferred continuous processes of recrystallizing annealing, such as those shown in the book "Manufacture of Cold-Rolled Strip", 1970, published by Stahleisen Düsseldorf in Fig. 28, offer the possibility of achieving significantly higher productivity in this one process step. OS 2 348 062 describes the use of these devices for producing cold-rolled steel strip with good forming properties from unsettled and calmed steels.
Es gehört weiterhin zum Stand der Technik, daß der Stahl nach der Glühbehandlung zur Einstellung einer für die Verarbeitung des Kaltbandes erforderlichen Alterungsbeständigkeit einer kurzzeitigen Überalterungsbehandlung im Bereich von etwa 250 bis 450° C unterzogen wird. Daran schließt sich die sogenannte "Dressierbehandlung" an.It is also part of the prior art that the steel is subjected to a brief aging treatment in the range from about 250 to 450 ° C. after the annealing treatment in order to achieve the aging resistance required for processing the cold strip. This is followed by the so-called "skin treatment".
Das vorgenannte Fachbuch schildert im übrigen recht ausführlich den Stand der Technik bei der Herstellung und Prüfung von kaltgewalztem Bandstahl. Für die verschiedenen Werkstoff-Kennwerte rm und nm wird auf S. 347 - 355 verwiesen. Weitere Werkstoffvorschriften sind DIN 1623 Teil 1, Ausgabe Febr. 1983 (weiche unlegierte Stähle zum Kaltumformen)und DIN 1624 zu entnehmen.The aforementioned specialist book describes the state of the art in the manufacture and testing of cold-rolled steel strip quite extensively. For the different material parameters r m and n m , see pages 347 - 355. Further material specifications can be found in DIN 1623 Part 1, February 1983 edition (soft unalloyed steels for cold forming) and DIN 1624.
Nach dem derzeitigen Stand der Technik ist die Herstellung alterungsbeständiger Bandstähle mit höchster Kaltumformbarkeit jedoch noch nicht befriedigend gelöst, insbesondere bestehen Wünsche
- nach ausschließlicher Verwendung kontinuierlicher Produktionsverfahren mit erhöhter Wirtschaftlichkeit
- nach verbesserten Eigenschaften der Fertigprodukte, differenziert nach den jeweiligen Verformungsverfahren, Werkstoffbeanspruchungen und -kennwerten.According to the current state of the art, however, the manufacture of age-resistant steel strips with the highest level of cold formability has not yet been satisfactorily resolved, in particular there are wishes
- After the exclusive use of continuous production processes with increased economy
- for improved properties of the finished products, differentiated according to the respective shaping process, material stresses and characteristics.
Hier setzt die Aufgabe der vorliegenden Erfindung ein; die Lösung der vorgenannten Aufgabe ist in Anspruch 1 in Verbindung mit den Ansprüchen 6 oder 7 beschrieben und besteht im wesentlichen in der Kombination folgender Maßnahmen:
- Verwendung einer bestimmten Stahlanalyse
- Begrenzung der Vorwärmtemperatur vor dem Warmwalzen
- Auswahl der Walzendtemperatur je nach bevorzugten Werkstoff-Kennwerten
- kontinuierliches rekristallisierendes Glühen.This is where the object of the present invention comes in; The solution to the aforementioned problem is described in claim 1 in conjunction with claims 6 or 7 and consists essentially in the combination of the following measures:
- Use a specific steel analysis
- Limitation of the preheating temperature before hot rolling
- Selection of the final roll temperature depending on the preferred material characteristics
- continuous recrystallizing annealing.
Die erfindungsgemäße Aufgabe wird im einzelnen dadurch gelöst, daß die nach dem Stand der Technik angewendeten hohen Brammenvorwärmtemperaturen bei dem neuen Verfahren verlassen, also abgesenkt werden. Je nach der für bestimmte Verwendungszwecke bevorzugten Kombination der Materialkennwerte wird auch die Walzendtemperatur differenziert, also das Warmwalzen bei einer Temperatur unterhalb oder oberhalb der Umwandlungstemperatur A₃ im letzten Fertiggerüst beendet.The object of the invention is achieved in detail in that the high slab preheating temperatures used in the prior art are exited in the new process, that is to say are lowered. Depending on the combination of the material characteristics preferred for certain purposes, the final rolling temperature is also differentiated, that is, the hot rolling is ended at a temperature below or above the
Es werden an sich bekannte kontinuierliche Verfahren der rekristallisierenden Glühung verwendet.Continuous methods of recrystallizing annealing, which are known per se, are used.
Im Gesamteffekt wird überraschender Weise ein in seinen Eigenschaften gezielt verbessertes Produkt erzielt.The overall effect is surprisingly achieved in a product whose properties are specifically improved.
Die erfindungsgemäß zu verwendenden Stahlanalysen sind im Hauptanspruch erwähnt; in den Ansprüchen 2, 3 und 4 sind vorzugsweise zu verwendende eingeengte Werte festgelegt.The steel analyzes to be used according to the invention are mentioned in the main claim; in
Für das Vorwärmen der Brammen vor dem Warmwalzen ist generell ein Temperraturbereich von ca. 1 100 - 1 300° C eingeführt ("Eisenhütte", Berlin 1961, S. 427). Üblicher Weise werden dabei, insbesondere für kontinuierliche Bandstraßen, die höheren Bereiche bevorzugt, weil bekanntlich mit zunehmender Temperatur die Warmverformbarkeit der Stähle verbessert wird, so daß der Energieverbrauch der Walzmotoren mit steigender Walzanfangstemperatur verringert werden kann, und weil auch - trotz des unvermeidlichen Temperaturabfalles vom Vorgerüst bis zum letzten Fertiggerüst - die Walzendtemperatur noch oberhalb der Gefügeumwandlungstemperatur A₃ liegt. Es wird als vorteilhaft angesehen, daß auch das letzte Gerüst der Fertigstaffel oberhalb A₃ durchlaufen wird.Die DE-OS 31 38 302, Anspruch 1, beschreibt ein Verfahren zur Herstellung von "kaltgewalztem Bandstahl hoher Festigkeit". Dabei wird auch eine Erwärmung der Stahlbrammen auf höchstens 1 200° C bzw. in den Bereich 1 200 bis 1 000° C vorgeschlagen. Die angestrebten Dehngrenzen liegen, wie Tab. 2 belegt, über 2o kp/mm². Hinweise auf die erfindungsgemäß herzustellenden, völlig anders zusammengesetzten Stähle, deren Umformverhalten und niedrigen Dehngrenzen sind dieser Druckschrift nicht zu entnehmen. Die Ansprüche 1 und 5 nennen die erfindungsgemäßen Ober- bzw. Untergrenzen der Brammenvorwärmtemperatur.For the preheating of the slabs before hot rolling, a temperature range of approximately 1 100-1 300 ° C is generally introduced ("Eisenhütte", Berlin 1961, p. 427). Usually, especially for continuous strip mills, the higher ranges are preferred because, as is known, the hot-formability of the steels is improved with increasing temperature, so that the energy consumption of the rolling motors can be reduced as the initial rolling temperature increases, and also - despite the inevitable drop in temperature from the roughing stand to the last finishing stand - the final roll temperature is still above the structural transformation temperature A₃. It is considered advantageous that the last frame of the finishing line is passed above A₃. DE-OS 31 38 302, claim 1, describes a process for producing "cold-rolled steel strip of high strength". A heating of the steel slabs to a maximum of 1200 ° C or in the range 1200 to 1000 ° C is also proposed. The desired yield strengths are, as Table 2 shows, over 20 kp / mm². This publication does not provide any references to the steels to be produced according to the invention, which have a completely different composition, their forming behavior and low yield strengths. Claims 1 and 5 name the upper and lower limits of the slab preheating temperature according to the invention.
Anspruch 6 legt (gegenüber dem Stand der Technik) abgesenkte Walzendtemperaturen fest. Die Auswirkung dieser Maßnahme ist in Fig. 1 anhand von Balkendiagrammen erläutert. Stahl 1 hat folgende Zusammensetzung (Masseprozente):
C 0,02%
Si 0,01%
Mn 0,2%
P 0,008%
S 0,012%
Al 0,04%
N 0,003%Claim 6 specifies (compared to the prior art) lower roll temperatures. The effect of this measure is explained in Fig. 1 using bar graphs. Steel 1 has the following composition (percentages by mass):
C 0.02%
Si 0.01%
Mn 0.2%
P 0.008%
S 0.012%
Al 0.04%
N 0.003%
Dieser Al-beruhigte Stahl weist einen geringen Legierungsgehalt auf und gehört nicht in die Gruppe der "mikrolegierten Stähle". Er wurde als Bramme nach dem Stand der Technik bei 1 270° C vorgewärmt und in herkömmlicher Weise warm mit einer Endtemperatur von 920° C und kalt ausgewalzt. Die wichtigsten fünf Werkstoffkennzahlen sind am linken Rande der Diagramme graphisch aufgezeichnet. Die Dehngrenze ist für hohe Ansprüche der Kaltumformung noch ausreichend; die Bruchdehnung genügt mit 40% nur knapp für sehr anspruchsvolle Verwendungszwecke. Ähnliches gilt für den Verfestigungskoeffizienten. In der rechten Hälfte der entsprechenden Felder sind die gleichen Kennwerte bei erfindungsgemäßer Herstellung des Kaltbandes dargestellt. Die Bramme wurde zunächst auf die niedrigste in Anspruch 5 genannte Temperaturspanne vorgewärmt und dann das Band, wie dem Fachmann geläufig ist, zwischen Vor- und Fertigstaffel gekühlt, so daß das Band aus dem letzten Fertiggerüst mit 800° C austrat. Die prozentuale Dickenabnahme des Bandes nach Durchlaufen der Umwandlungstemperatur erreichte noch 40%. Aus diesem Warmband hergestelltes Kaltband erreichte trotz des geringen Legierungsaufwandes so günstige Werte von Dehngrenze, Bruchdehnung und Verfestigungsexponent, daß diese Erzeugnisse auch für anspruchsvollste Verwendungszwecke unter Einsatz von Streckziehen und dreidimensionalem Abkanten eingesetzt werden können. Allerdings ist der Kennwert der senkrechten Anisotropie rm mit 1,3 nicht ausreichend für die Herstellung komplizierter Tiefziehteile.This Al-calmed steel has a low alloy content and does not belong to the group of "micro-alloyed steels". It was preheated as a slab according to the prior art at 1 270 ° C and rolled in a conventional manner warm with a final temperature of 920 ° C and cold. The most important five material key figures are graphically recorded on the left edge of the diagrams. The yield strength is still sufficient for high cold forming requirements; At 40%, the elongation at break is barely sufficient for very demanding applications. The same applies to the hardening coefficient. The same characteristic values are shown in the right half of the corresponding fields when the cold strip is produced according to the invention. The slab was first preheated to the lowest temperature range mentioned in claim 5 and then, as is known to the person skilled in the art, the strip was cooled between the preliminary and the finished batch, so that the strip emerged from the last finishing stand at 800 ° C. The percentage decrease in thickness of the strip after passing through the transition temperature still reached 40%. Cold strip made from this hot strip, despite the low alloying effort, achieved such favorable values of yield strength, elongation at break and strengthening exponent that these products can also be used for the most demanding purposes using stretch drawing and three-dimensional folding. However, the characteristic value of the vertical anisotropy r m with 1.3 is not sufficient for the production of complicated deep-drawn parts.
Anspruch 7 legt für das Warmwalzverfahren fest, daß der gesamte Walzvorgang beendet wird (also das letzte Fertiggerüst durchlaufen wird), ehe das Walzgut unter den A₃ - Punkt erkaltet. Dabei handelt es sich um erfindungsgemäße Stähle; für Beispiel 2 ist der gleiche legierungsarme Stahl verwandt, der auch nach Beispiel 1 hergestellt und anschließend untersucht wurde. Für Beispiel 3 lautet die (erfindungsgemäße) Analyse in Masseprozenten:
C 0,005%
Si 0,01%
Mn 0,18%
P 0,006%
S 0,014%
Al 0,03%
N 0,004%
Ti 0,09%Claim 7 specifies for the hot rolling process that the entire rolling process is ended (that is, the last finishing stand is run through) before the rolling stock cools below the A₃ point. These are steels according to the invention; for example 2 the same low-alloy steel is used, which was also produced according to example 1 and subsequently examined. For example 3, the analysis according to the invention is in percentages by mass:
C 0.005%
Si 0.01%
Mn 0.18%
P 0.006%
S 0.014%
Al 0.03%
N 0.004%
Ti 0.09%
Dieser Stahl wurde im Stahlwerk aufwendiger hergestellt, und zwar vakuumentkohlt und zudem mit Ti legiert.This steel was produced in the steelworks more elaborately, namely vacuum decarburized and also alloyed with Ti.
Wie Fig. 1 in den entsprechenden Spalten belegt, zeigt sich bei Beispiel 2, daß die linken Balken, die den Stand der Technik darstellen, mit einer Brammenvorwärmtemperatur von 1 270 und einer Walzendtemperatur von 920° C keine Kennzahlen für höchste Kaltumformbarkeit aufweisen: Die Dehngrenze mit 190 N/mm², die Bruchdehnung mit 40% und der Verfestigungsexponent mit 0,22 sind noch nicht optimal. Wesentlich günstiger sind die Werte des erfindungsgemäß hergestellten Bandes: trotz seiner knappen Legierung: niedrigere Dehngrenze mit 160 N/mm²; deutlich angehobene Bruchdehnung und besserer Vefestigungsexponent als Folge der niedrigen Brammenvorwärmteperatur und der Walzendtemperatur mit 920 ° C.As shown in Fig. 1 in the corresponding columns, it can be seen in Example 2 that the left bars, which represent the state of the art, with a slab preheating temperature of 1 270 and a roll end temperature of 920 ° C, do not have any key figures for maximum cold formability: the proof stress with 190 N / mm², the elongation at break with 40% and the hardening exponent with 0.22 are not yet optimal. The values of the strip produced according to the invention are considerably more favorable: despite its scarce alloy: lower yield strength with 160 N / mm²; significantly higher elongation at break and better fastening exponent as a result of the low slab preheating temperature and the final roll temperature of 920 ° C.
Ebenso sind die im Beispiel 3 dargestellten Werkstoffkennwerte bei dem Herstellverfahren nach dem Stand der Technik weniger günstig; dagegen werden sie nach dem erfindungsgemäßen Herstellverfahren deutlich verbessert.Likewise, the material characteristics shown in Example 3 are less favorable in the manufacturing process according to the prior art; in contrast, they are significantly improved by the manufacturing process according to the invention.
Anspruch 8 hat die Anwendung des erfindungsgemäßen Verfahrens unter Einsatz der an sich bekannten kontinuierlichen Banddurchziehöfen zum Inhalt.Claim 8 relates to the use of the method according to the invention using the continuous strip drawing yards known per se.
Ansprüche 9 und 10 betreffen die Verbindung des erfindungsgemäßen Herstellverfahrens mit einer an sich bekannten Überalterungsbehandlung bzw. mit dem Aufbringen eines metallischen Schutzüberzuges im Schmelzfluß.Claims 9 and 10 relate to the connection of the manufacturing method according to the invention with a known aging treatment or with the application of a metallic protective coating in the melt flow.
Wie aus den vorstehenden Ausführungen und den Beispielen ersichtlich, führt die erfindungsgemäße Kombination der genannten Verfahrensschritte dahin, daß mit verbesserter Produktivität kaltgewalzte Bandstähle zuverlässiger und mit für bestimmte Verwendungszwecke gezielt verbesserter Kaltumformbarkeit hergestellt werden können.As can be seen from the above explanations and the examples, the combination according to the invention of the process steps mentioned leads to the fact that cold-rolled strip steels can be produced more reliably with improved productivity and with improved cold formability for specific purposes.
Gegenüber dem erhöhten Energiebedarf beim Warmwalzen überwiegen die Vorteile des erfindungsgemäßen Verfahrens. Es seien hierfür nur einige Beispiele genannt:
- kürzere Durchsatzzeiten und damit erhöhte Leistung der Ofenanlage für die Brammenvorwärmung
- geringere Verzunderung, also höheres Gewichtsausbringen
- gezielte Kombination der Werkstoffkennwerte für unterschiedliche Kaltumformverfahren
gesteigerter Einsatz von leistungssteigernden kontinuierlichen Verfahrensschritten sämtlicher ArbeitsgängeThe advantages of the method according to the invention outweigh the increased energy requirements in hot rolling. Here are just a few examples:
- Shorter throughput times and thus increased performance of the furnace system for slab preheating
- less scaling, i.e. higher weight output
- Targeted combination of material properties for different cold forming processes
increased use of performance-enhancing continuous process steps in all work processes
Claims (10)
max. 0,06% C
max. 0,10% Si
max. 0,40% Mn
max. 0,03% P
max. 0,03% S
max. 0,01% N
mindestens einem der fünf Elemente aus nachfolgender Gruppe
0 - 0,10% Al,
0 - 0,006% B
0 - 0,20% Ti
0 - 0,20 Nb
0 - 0,20% V
erschmelzungsbedingten Verunreinigungen,
Rest Eisen
zu Brammen vergossen, vor dem Warmwalzen auf Temperaturen bis höchstens 1 200° C erwärmt, ausgewalzt, gehaspelt und anschließend rekristallisierend auf Dehngrenzen von höchstens 200 N/mm² geglüht werden.1. A process for producing an aging-resistant steel strip with high cold formability by hot strip rolling, cold rolling, recrystallizing annealing and subsequent tempering, characterized in that steels (details in percent by mass) with
Max. 0.06% C
Max. 0.10% Si
Max. 0.40% Mn
Max. 0.03% P
Max. 0.03% S
Max. 0.01% N
at least one of the five elements from the following group
0-0.10% Al,
0 - 0.006% B
0-0.20% Ti
0 - 0.20 Nb
0 - 0.20% V
contamination due to melting,
Rest of iron
cast into slabs, heated to temperatures up to a maximum of 1200 ° C, rolled, coiled and then recrystallized and annealed to yield strengths of up to 200 N / mm² before hot rolling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT86109521T ATE104362T1 (en) | 1985-08-10 | 1986-07-11 | PROCESS FOR PRODUCTION OF AN AGING-RESISTANT STEEL STRIP WITH HIGH COLD FORMABILITY. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19853528782 DE3528782A1 (en) | 1985-08-10 | 1985-08-10 | METHOD FOR PRODUCING AN AGING-RESISTANT STRIP STEEL WITH HIGH COLD FORMABILITY |
| DE3528782 | 1985-08-10 |
Publications (4)
| Publication Number | Publication Date |
|---|---|
| EP0216044A2 true EP0216044A2 (en) | 1987-04-01 |
| EP0216044A3 EP0216044A3 (en) | 1989-06-14 |
| EP0216044B1 EP0216044B1 (en) | 1994-04-13 |
| EP0216044B2 EP0216044B2 (en) | 1997-09-03 |
Family
ID=6278246
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86109521A Expired - Lifetime EP0216044B2 (en) | 1985-08-10 | 1986-07-11 | Process for manufacturing non-aging steel strip having a high cold formability |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0216044B2 (en) |
| AT (1) | ATE104362T1 (en) |
| DE (2) | DE3528782A1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2810245B2 (en) * | 1991-01-25 | 1998-10-15 | 日本鋼管株式会社 | Cold rolled steel sheet excellent in press formability and phosphatability and method for producing the same |
| JP3422612B2 (en) * | 1996-01-19 | 2003-06-30 | Ｊｆｅスチール株式会社 | Manufacturing method of ultra low carbon cold rolled steel sheet |
| DE19701443A1 (en) * | 1997-01-17 | 1998-07-23 | Thyssen Stahl Ag | Cold rolled steel sheet or strip with good formability used for car parts production |
| 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 |
| DE19834361A1 (en) * | 1998-07-30 | 2000-02-03 | Schaeffler Waelzlager Ohg | Precision deep-drawn case-hardened component, especially a roller bearing and motor component e.g. a needle bearing, sleeve or bush, is made from a cold rolled strip of steel with specified titanium, nitrogen and low aluminum contents |
| DE19840788C2 (en) * | 1998-09-08 | 2000-10-05 | Thyssenkrupp Stahl Ag | Process for producing cold-rolled strips or sheets |
| DE19946889C1 (en) * | 1999-09-30 | 2000-11-09 | Thyssenkrupp Stahl Ag | Aging resistant aluminum-killed steel strip, for manufacturing cold formed components e.g. bodywork parts, is produced by subjecting rolled strip to continuous annealing, hot coiling, cooling to room temperature and skin pass rolling |
| 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 |
| CN107099648A (en) * | 2017-06-27 | 2017-08-29 | 中国航空工业集团公司沈阳飞机设计研究所 | The structure property homogenization heat treatment method of the steel of laser deposition molding A 100 |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2286195A1 (en) * | 1974-09-24 | 1976-04-23 | Armco Steel Corp | Strengthening low carbon steel sheet - by nitriding after rolling to form fine nitride dispersion |
| EP0024437A1 (en) * | 1979-02-27 | 1981-03-11 | Kawasaki Steel Corporation | Process for producing non-aging cold-rolled steel sheets |
| JPS56166330A (en) * | 1980-04-25 | 1981-12-21 | Nippon Steel Corp | Manufacture of cold rolled steel plate for deep drawing by continuous annealing |
| GB2085331A (en) * | 1980-09-25 | 1982-04-28 | Nippon Steel Corp | Process for producing cold rolled steel strip useful for motor vehicles |
| EP0072874A1 (en) * | 1981-08-25 | 1983-03-02 | Nippon Steel Corporation | Dual-purpose plant for producing cold rolled steel sheet and hot-dip galvanized steel sheet |
| US4473411A (en) * | 1983-07-20 | 1984-09-25 | Armco Inc. | Process of making aluminum killed low manganese deep drawing steel |
| EP0108268B1 (en) * | 1982-10-08 | 1987-03-11 | Nippon Steel Corporation | Method for the production of cold rolled steel sheet having super deep drawability |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6045689B2 (en) * | 1982-02-19 | 1985-10-11 | 川崎製鉄株式会社 | Method for manufacturing cold rolled steel sheet with excellent press formability |
-
1985
- 1985-08-10 DE DE19853528782 patent/DE3528782A1/en active Granted
-
1986
- 1986-07-11 AT AT86109521T patent/ATE104362T1/en not_active IP Right Cessation
- 1986-07-11 DE DE3689781T patent/DE3689781D1/en not_active Expired - Fee Related
- 1986-07-11 EP EP86109521A patent/EP0216044B2/en not_active Expired - Lifetime
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2286195A1 (en) * | 1974-09-24 | 1976-04-23 | Armco Steel Corp | Strengthening low carbon steel sheet - by nitriding after rolling to form fine nitride dispersion |
| EP0024437A1 (en) * | 1979-02-27 | 1981-03-11 | Kawasaki Steel Corporation | Process for producing non-aging cold-rolled steel sheets |
| JPS56166330A (en) * | 1980-04-25 | 1981-12-21 | Nippon Steel Corp | Manufacture of cold rolled steel plate for deep drawing by continuous annealing |
| GB2085331A (en) * | 1980-09-25 | 1982-04-28 | Nippon Steel Corp | Process for producing cold rolled steel strip useful for motor vehicles |
| EP0072874A1 (en) * | 1981-08-25 | 1983-03-02 | Nippon Steel Corporation | Dual-purpose plant for producing cold rolled steel sheet and hot-dip galvanized steel sheet |
| EP0108268B1 (en) * | 1982-10-08 | 1987-03-11 | Nippon Steel Corporation | Method for the production of cold rolled steel sheet having super deep drawability |
| US4473411A (en) * | 1983-07-20 | 1984-09-25 | Armco Inc. | Process of making aluminum killed low manganese deep drawing steel |
Non-Patent Citations (1)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN, Band 6, Nr. 54 (C-97)[932], 9. April 1982; & JP-A-56 166 330 (SHIN NIPPON SEITETSU K.K.) 21-12-1981 * |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3528782A1 (en) | 1987-02-19 |
| DE3689781D1 (en) | 1994-05-19 |
| EP0216044A3 (en) | 1989-06-14 |
| EP0216044B2 (en) | 1997-09-03 |
| DE3528782C2 (en) | 1990-06-13 |
| EP0216044B1 (en) | 1994-04-13 |
| ATE104362T1 (en) | 1994-04-15 |
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