EP0181583A2 - Method of making a dual-phase hot-rolled steel strip - Google Patents
Method of making a dual-phase hot-rolled steel strip Download PDFInfo
- Publication number
- EP0181583A2 EP0181583A2 EP85113944A EP85113944A EP0181583A2 EP 0181583 A2 EP0181583 A2 EP 0181583A2 EP 85113944 A EP85113944 A EP 85113944A EP 85113944 A EP85113944 A EP 85113944A EP 0181583 A2 EP0181583 A2 EP 0181583A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- temperature
- rolling
- hot
- range
- slab
- 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.)
- Granted
Links
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
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Definitions
- the invention relates to a method for producing hot strip with a two-phase structure from a slab previously produced by block casting or continuous casting, which contains iron, carbon, manganese, silicon and chromium as essential constituents, by heating the slab to the rolling temperature Hot and finish rolling at a temperature> Ar3, by accelerated cooling from the rolling heat and by coiling at a relatively low temperature.
- the slab which is essentially 0.05-0.20% C, 0.5-1.5% Mn and 0.5-2.0% Si and possibly Cr, V, Mo, Ti and Nb, remainder iron, hot-rolled in the austenitic state, then cooled to a temperature in the range of approx. 800 - 650 ° C, coiled and held at this temperature for at least one minute. Subsequently, the strip is unwound in a further process step, cooled to a temperature ⁇ 450 ° C. at a speed> 10 ° C./s and finally rewound at this temperature.
- the slab heated to the rolling temperature which is essentially 0.02-0.20% C, 0.5-2.0% Mn, 0.05-2.0% Si and 0.3 - 1.5% Cr as well as ⁇ 0.15% P and ⁇ 0.1% Al, rest iron contains hot rolled with a final rolling temperature> 780 ° C.
- the hot strip is cooled at a speed> 40 ° C./s to an intermediate temperature T N in the order of magnitude of approximately 750-650 ° C. and kept at this temperature for at least 5 seconds. This is followed by a further accelerated cooling at a rate> 50 ° C./s to a temperature in the range from 550-200 ° C. before the strip is finally coiled at this temperature.
- both cooling processes mean complex cooling sections or, in the case of the process known from EP-B-19 193, a second unwinding and winding device for the finished rolled hot strip.
- EP-A-68 598 discloses a method for producing hot strip with a two-phase structure, low yield ratio and good formability, in which, in contrast to the two aforementioned methods, the hot strip after finishing rolling to a low coiling temperature without additional effort is cooled. This is essentially achieved in that the slab in addition to 0.03 - 0.15% C, 0.6 - 1.8% Mn, ⁇ 0.10% Al, ⁇ 0.008% S and possibly 0.2 - 2 , 0% Si alone or together with Cr has an increased phosphorus content in the range of 0.04-0.20), the rest contains iron.
- the slab must be heated to a certain temperature in the specified range of 1,100 - 1,250 ° C before it is then hot-rolled and finish-rolled at a temperature in the range of 900 - 780 ° C and after finish-rolling at a speed in the range of 10 - 200 ° C / s is cooled and finally can be coiled at a temperature ⁇ 450 ° C.
- This previously known method has the advantage that the hot strip can be produced on conventional rolling mills with the associated cooling section without additional equipment.
- the increase in the phosphorus content means a deterioration in the weldability of the hot strip.
- the tendency of the hot strip to embrittlement increases with increasing or increased phosphorus content.
- This temper embrittlement is particularly noticeable when it comes from the hot strip with which it high phosphorus produced sheet must then be welded during further processing, for example.
- the temperature of the furnace for heating and heating the slab must be set exactly to the rolling temperature, this temperature also being below the usual temperatures from the predetermined temperature range.
- the object of the invention is to provide a method for producing hot strip with a two-phase structure which, with at least the same property profile, namely low yield ratio (below approx. 0.70), isotropic cold formability, good weldability, with simple means, especially on conventional rolling mills with associated cooling section, ie can be produced without additional equipment.
- the manganese content of the steel from which the slab is first produced and then the hot strip is reduced and to a low value in the range from 0.20 to 0.40%. is set.
- the carbon content of the steel is preferably set to a value in the range from 0.05 to 0.12%.
- the slab produced from a steel of the claimed composition can then be heated to the usual rolling temperature and heated through using the method according to the invention. No special measures are required in this regard.
- the hot and finished rolling of the heated slab into the hot strip takes place at a temperature above and as close as possible to A r3 .
- this deformation during hot rolling and in particular during finish rolling in the last two stands of the finishing train no further special measures are necessary when using the method according to the invention.
- the deformation in the last two stands of the prefabricated structure is a maximum of 25%, preferably about 15%.
- the hot strip is cooled according to the invention immediately after finish rolling with a final rolling temperature above A r3 at an average speed in the range from 30 to 70 ° C./s and without interruptions and then coiled at a temperature in the range from 350 to 190 ° C. .
- the slab additionally contains 0.01 to 0.04% titanium in a stoichiometric ratio to nitrogen in order to achieve an improvement in the cold formability at the low coiling temperature according to the invention.
- nitrogen aging of the finished rolled hot strip or the sheets produced therefrom is avoided.
- the main advantage of the method according to the invention is that hot strip with a two-phase structure made of fine-grained, globular ferrite (> 80%) and grains of martensite dispersed therein can be produced on conventional hot strip mills with the associated downstream cooling section. Furthermore, the method according to the invention enables known measures to accelerate ferrite formation and its negative effects, such as to dispense with a high final deformation during hot rolling and finish rolling in the two-phase area.
- a high final deformation means undesirable high rolling forces and a deterioration in strip flatness and strip geometry and finish rolling in the two-phase area also mean high rolling forces, a deterioration in cold formability and anisotropic mechanical properties of the hot rolled strip.
- an Mn content of at least 0.6% is required to set the two-phase structure
- this also has a reduced Mn content according to the invention , preferably in the range of 0.2-0.4%.
- Another advantage of the method according to the invention is that the manufacturing costs are reduced due to the reduced Mn content.
- the low Mn content according to the invention advantageously has the effect that practically no stretched sulfides (MnS) form, which usually cause deterioration of the cold formability, in particular in the transverse direction, in high-strength steels.
- the method according to the invention makes it possible to dispense with the increased addition of phosphorus, which leads to embrittlement.
- the preferred phosphorus content is limited to 4 0.015%.
- hot strip with a two-phase structure made of> 80% fine-grained, globular ferrite and martensite and with a yield point ratio of ⁇ 0.70 can be produced with the aid of the method according to the invention, which can be welded without problems and in both the longitudinal and transverse directions has good uniform cold formability.
- Another advantage of the method according to the invention is that an additional increase in the yield strength is achieved in the hot strip produced by the method after deformation and subsequent tempering treatment, for example by burning in an applied lacquer layer. Furthermore, the low alloy content enables the production of hot strip with a two-phase structure with tensile strengths of 500 to 600 N / mm 2 , which are particularly suitable for the production of parts that require high cold formability.
- Continuous cast slabs with the chemical compositions A and B given in Table 1 were first heated to a temperature of approximately 1,250 ° C. and heated through. Subsequently, they were hot-rolled at a temperature above A r3 and finish- rolled to a final thickness d (see Table 2). The final rolling or finish rolling temperature was placed as close as possible to A r3 . Subsequently, the finished rolled strips were cooled with a medium speed in the range of 30-70 ° C./s on a conventional cooling section downstream of the hot strip mill without interruptions and wound up at the various reel temperatures HT shown in Table 2. The mechanical properties of the finished rolled sheets, as summarized in Table 2, resulted.
- Table 2 shows that the reel temperature HT should preferably be set to a temperature above 200 ° C, because at a lower reel temperature, s.
- Samples A3 and B3 the yield strength ratio increased again and the elongation at break A 5 decreased to even worse values. However, both have an unfavorable effect on the cold formability of the hot strip or sheet.
- an artificial aging treatment at 100 ° C and for about an hour showed no change in the yield strength.
- an increase in the yield strength in the range of 40-80 N / mm 2 was determined after a tempering treatment at approx. 170 ° C. and 20 minutes after the strips or sheets had previously been given a three percent Have been subjected to pre-deformation.
Abstract
Description
Die Erfindung bezieht sich auf ein Verfahren zur Herstellung von Warmband mit einem Zweiphasen-Gefüge aus einer zuvor durch Blockgießen oder Stranggießen hergestellten Bramme, die neben Eisen als wesentliche Bestandteile Kohlenstoff, Mangan, Silizium und Chrom enthält, durch Erwärmen der Bramme bis auf Walztemperatur, durch Warm- und Fertigwalzen bei einer Temperatur > Ar3, durch beschleunigtes Abkühlen aus der Walzhitze und durch Haspeln bei verhältnismäßig niedriger Temperatur.The invention relates to a method for producing hot strip with a two-phase structure from a slab previously produced by block casting or continuous casting, which contains iron, carbon, manganese, silicon and chromium as essential constituents, by heating the slab to the rolling temperature Hot and finish rolling at a temperature> Ar3, by accelerated cooling from the rolling heat and by coiling at a relatively low temperature.
Ein derartiges Verfahren zur Herstellung von Warmband mit einem Zweiphasen-Gefüge aus.feinkörnigem Ferrit ( > 70 %) und darin dispergierten Körnern aus Martensit, bei dem die im wesentlichen Kohlenstoff, Mangan, Silizium und Chrom enthaltene Bramme zunächst auf Warmwalztemperatur erwärmt, anschließend oberhalb Ar3 warm- und fertiggewalzt, im Anschluß daran beschleunigt abgekühlt und schließlich bei niedriger Temperatur gehaspelt wird, ist aus der EP-B-19 193 und aus der EP-A-72 867 bekannt.Such a process for the production of hot strip with a two-phase structure made of fine-grained ferrite (> 70%) and grains of martensite dispersed therein, in which the slab essentially containing carbon, manganese, silicon and chromium is first heated to hot rolling temperature, then above A r3 hot-rolled and finish- rolled, then accelerated and finally coiled at low temperature, is known from EP-B-19 193 and from EP-A-72 867.
Bei dem aus der EP-B-19 193 bekannten Verfahren wird die Bramme, die im wesentlichen 0,05 - 0,20 % C, 0,5 - 1,5 % Mn und 0,5 - 2,0 % Si sowie ggf. Cr, V, Mo, Ti und Nb, Rest Eisen enthält, im austenitischen Zustand warmgewalzt, anschließend bis auf eine Temperatur im bereich von ca. 800 - 650 °C abgekühlt, gehaspelt und bei dieser Temperatur mindestens eine Minute lang gehalten. Im Anschluß daran wird das Band in einem weiteren Verfahrensschritt abgewickelt, mit einer Geschwindigkeit >10 °C/s auf eine Temperatur < 450 °C gekühlt und schließlich bei dieser Temperatur erneut gehaspelt.In the process known from EP-B-19 193, the slab, which is essentially 0.05-0.20% C, 0.5-1.5% Mn and 0.5-2.0% Si and possibly Cr, V, Mo, Ti and Nb, remainder iron, hot-rolled in the austenitic state, then cooled to a temperature in the range of approx. 800 - 650 ° C, coiled and held at this temperature for at least one minute. Subsequently, the strip is unwound in a further process step, cooled to a temperature <450 ° C. at a speed> 10 ° C./s and finally rewound at this temperature.
Bei dem aus der EP-A-72 867 bekannten Verfahren wird die auf Walztemperatur erwärmte Bramme, die im wesentlichen 0,02 - 0,20 % C, 0,5 - 2,0 % Mn, 0,05 - 2,0 % Si und 0,3 - 1,5 % Cr sowie ≤ 0,15 % P und ≤ 0,1 % Al, Rest Eisen enthält, mit einer Endwalztemperatur > 780 °C warmgewalzt. Nach dem Verlassen der Fertigstaffel wird das Warmband mit einer Geschwindigkeit >40 °C/s auf eine Zwischentemperatur TN in der Größenordnung von ca. 750 - 650 °C abgekühlt und mindestens 5 Sekunden lang auf dieser Temperatur gehalten. Im Anschluß daran erfolgt eine weitere beschleunigte Abkühlung mit einer Geschwindigkeit >50 °C/s auf eine Temperatur im Bereich von 550 - 200 °C, bevor das Band schließlich bei dieser Temperatur gehaspelt wird.In the process known from EP-A-72 867, the slab heated to the rolling temperature, which is essentially 0.02-0.20% C, 0.5-2.0% Mn, 0.05-2.0% Si and 0.3 - 1.5% Cr as well as ≤ 0.15% P and ≤ 0.1% Al, rest iron contains hot rolled with a final rolling temperature> 780 ° C. After leaving the finishing line, the hot strip is cooled at a speed> 40 ° C./s to an intermediate temperature T N in the order of magnitude of approximately 750-650 ° C. and kept at this temperature for at least 5 seconds. This is followed by a further accelerated cooling at a rate> 50 ° C./s to a temperature in the range from 550-200 ° C. before the strip is finally coiled at this temperature.
Mit beiden vorbekannten Verfahren werden ein geringes Streckgrenzenverhältnis ( < ca. 0,70) und gute Kaltumformbarkeit des warmgewalzten Bandes bzw. der daraus erzeugten Bleche erzielt. Um das entsprechene Zweiphasen-Gefüge einzustellen, sind jedoch in beiden Fällen ein gesteuertes bzw. gestuftes Abkühlverfahren nach dem Warm- bzw. Fertigwalzen des Warmbandes vorgesehen. Es wechseln Phasen der beschleunigten Abkühlung und Phasen des Haltens des Warmbandes bei einer bestimmten Temperatur (Abkühlung an ruhender Luft) miteinander ab. Vorrichtungsmäßig bedeuten beide Abkühlverfahren aufwendige Kühlstrecken bzw. im Falle des aus der EP-B-19 193 vorbekannten Verfahrens eine zweite Ab- und Aufwickelvorrichtung für das fertiggewalzte Warmband.With both previously known methods, a low yield ratio (<approx. 0.70) and good cold formability of the hot-rolled strip or the sheets produced therefrom are achieved. In order to set the corresponding two-phase structure, a controlled or stepped cooling process is provided in both cases after the hot or finish rolling of the hot strip. There are phases of accelerated cooling and phases of keeping warm bandes together at a certain temperature (cooling in still air). In terms of the device, both cooling processes mean complex cooling sections or, in the case of the process known from EP-B-19 193, a second unwinding and winding device for the finished rolled hot strip.
Andererseits ist aus der EP-A-68 598 ein Verfahren zum Herstellen von Warmband mit einem Zweiphasen-Gefüge, niedrigem Streckgrenzenverhältnis und guter Umformbarkeit bekannt, bei dem im Unterschied zu den beiden vorgenannten Verfahren das Warmband nach dem Fertigwalzen ohne zusätzlichen Aufwand auf eine niedrige Haspeltemperatur abgekühlt wird. Dies wird im wesentlichen dadurch erreicht, daß die Bramme neben 0,03 - 0,15 % C, 0,6 - 1,8 % Mn, ≤ 0,10 % Al, ≤ 0,008 % S und ggf. 0,2 - 2,0 % Si allein oder zusammen mit Cr einen erhöhten Phosphorgehalt im Bereich von 0,04 - 0,20 ) , Rest Eisen enthält. Zusätzlich muß die Bramme auf eine bestimmte Temperatur in dem vorgegebenen Bereich von 1.100 - 1.250 °C erwärmt werden bevor sie anschließend warmgewalzt und bei einer Temperatur im Bereich von 900 - 780 °C fertiggewalzt sowie nach dem Fertigwalzen mit einer Geschwindigkeit im Bereich von 10 - 200 °C/s abgekühlt wird und schließlich bei einer Temperatur ≤ 450 °C gehaspelt werden kann. Zwar besitzt dieses vorbekannte Verfahren den Vorteil, daß das Warmband auf herkömmlichen Walzstraßen mit der zugehörigen Kühlstrecke ohne zusätzlichen apparativen Aufwand hergestellt werden kann. Andererseits bedeutet jedoch die Erhöhung des Phosphorgehaltes eine Verschlechterung der Schweißbarkeit des Warmbandes. Des weiteren nimmt die Neigung zur Anlaßversprödung des Warmbandes mit zunehmendem bzw. erhöhtem Phosphorgehalt zu. Diese Anlaßversprödung macht sich insbesondere dann negativ bemerkbar, wenn das aus dem Warmband mit dem erhöhten Phosphorgehalt hergestellte blech anschließend bei der Weiterverarbeitung beispielsweise geschweißt werden muß. Darüber hinaus muß bei diesem vorbekannten Verfahren die Temperatur des Ofens zur Erwärmung und Durchwärmung der Bramme bis auf Walztemperatur exakt eingestellt werden, wobei diese Temperatur aus dem vorgegebenen Temperaturbereich darüber hinaus unterhalb der üblichen Temperaturen liegt.On the other hand, EP-A-68 598 discloses a method for producing hot strip with a two-phase structure, low yield ratio and good formability, in which, in contrast to the two aforementioned methods, the hot strip after finishing rolling to a low coiling temperature without additional effort is cooled. This is essentially achieved in that the slab in addition to 0.03 - 0.15% C, 0.6 - 1.8% Mn, ≤ 0.10% Al, ≤ 0.008% S and possibly 0.2 - 2 , 0% Si alone or together with Cr has an increased phosphorus content in the range of 0.04-0.20), the rest contains iron. In addition, the slab must be heated to a certain temperature in the specified range of 1,100 - 1,250 ° C before it is then hot-rolled and finish-rolled at a temperature in the range of 900 - 780 ° C and after finish-rolling at a speed in the range of 10 - 200 ° C / s is cooled and finally can be coiled at a temperature ≤ 450 ° C. This previously known method has the advantage that the hot strip can be produced on conventional rolling mills with the associated cooling section without additional equipment. On the other hand, however, the increase in the phosphorus content means a deterioration in the weldability of the hot strip. Furthermore, the tendency of the hot strip to embrittlement increases with increasing or increased phosphorus content. This temper embrittlement is particularly noticeable when it comes from the hot strip with which it high phosphorus produced sheet must then be welded during further processing, for example. In addition, in this previously known method, the temperature of the furnace for heating and heating the slab must be set exactly to the rolling temperature, this temperature also being below the usual temperatures from the predetermined temperature range.
Aufgabe der Erfindung ist nun die Schaffung eines Verfahrens zur Erzeugung von Warmband mit Zweiphasen-Gefüge das bei mindestens gleich gutem Eigenschaftsprofil, nämlich niedrigem Streckgrenzenverhältnis (unter ca. 0,70), isotroper Kaltumformbarkeit, guter Schweißbarkeit, mit einfachen Mitteln, insbesondere auf herkömmlichen Walzstraßen mit zugehöriger Kühlstrecke, d.h. ohne zusätzlichen apparativen Aufwand hergestellt werden kann.The object of the invention is to provide a method for producing hot strip with a two-phase structure which, with at least the same property profile, namely low yield ratio (below approx. 0.70), isotropic cold formability, good weldability, with simple means, especially on conventional rolling mills with associated cooling section, ie can be produced without additional equipment.
Erfindungsgemäß wird diese Aufgabe durch ein Verfahren der eingangs genannten Art dadurch gelöst, daß das Warmband
- a) aus einem Stahl erzeugt wird, der neben 0,05 bis 0,16 % C, 0,5 bis 1,0 % Si, 0,3 bis 1,5 % Cr, 0, 025 % P, ≤ 0,015 % S, 0,02 bis 0,10 % Al und ≤ 0,011 % N, 0,2 bis 0,4 % Mn, Rest Eisen und die üblichen Verunreinigungen enthält,
- b) unmittelbar nach dem Fertigwalzen von der Endwalztemperatur bis auf die Haspeltemperatur mit einer mittleren Geschwindigkeit im Bereich von 30 bis 70 °C/s und ohne Unterbrechungen beschleunigt abgekühlt wird und
- c) anschließend bei einer Temperatur im Breich von 350 bis 190 °C gehaspelt wird.
- a) is produced from a steel which, in addition to 0.05 to 0.16% C, 0.5 to 1.0% Si, 0.3 to 1.5% Cr, 0, 025% P, ≤ 0.015% S , 0.02 to 0.10% Al and ≤ 0.011% N, 0.2 to 0.4% Mn, balance iron and the usual impurities,
- b) is cooled immediately after the finish rolling from the finish rolling temperature to the coiling temperature at an average speed in the range of 30 to 70 ° C / s and without interruptions and
- c) is then coiled at a temperature in the range of 350 to 190 ° C.
Im Vergleich zu dem vorgenannten bereits bekannten Stand der Technik ist erfindungswesentlich, daß der Mangan-Gehalt des Stahles, aus dem zunächst die Bramme und anschließend das Warmband hergestellt werden, reduziert und auf einen niedrigen Wert im Bereich von 0,20 bis 0,40 % eingestellt wird. Vorzugsweise wird dabei gleichzeitig der Kohlenstoffgehalt des Stahles auf einen Wert im Bereich von 0,05 bis 0,12 % eingestellt.In comparison with the previously known state of the art, it is essential to the invention that the manganese content of the steel from which the slab is first produced and then the hot strip is reduced and to a low value in the range from 0.20 to 0.40%. is set. At the same time, the carbon content of the steel is preferably set to a value in the range from 0.05 to 0.12%.
Die aus einem Stahl der beanspruchten Zusammensetzung erzeugte Bramme kann nach dem erfindungsgemäßen Verfahren anschließend auf die übliche Walztemperatur erwärmt und durcherwärmt werden. Diesbezüglich sind keine besonderen Maßnahmen erforderlich.The slab produced from a steel of the claimed composition can then be heated to the usual rolling temperature and heated through using the method according to the invention. No special measures are required in this regard.
Erfindungsgemäß erfolgt das Warm- und Fertigwalzen der durcherwärmten Bramme zu dem Warmband bei einer Temperatur oberhalb und möglichst dicht an Ar3. Auch bezüglich dieser Verformung während des Warmwalzens und insbesondere während des Fertigwalzens in den letzten beiden Gerüsten der Fertigstaffel sind bei Anwendung des erfindungsgemäßen Verfahrens darüber hinaus keine weiteren besonderen Maßnahmen notwendig. So beträgt die Verformung in den letzten beiden Gerüsten der Fertigstaffel pro Gerüst maximal 25 %, vorzugsweise etwa 15 %.According to the invention, the hot and finished rolling of the heated slab into the hot strip takes place at a temperature above and as close as possible to A r3 . With regard to this deformation during hot rolling and in particular during finish rolling in the last two stands of the finishing train, no further special measures are necessary when using the method according to the invention. For example, the deformation in the last two stands of the prefabricated structure is a maximum of 25%, preferably about 15%.
Im Anschluß daran wird das Warmband erfindungsgemäß unmittelbar nach dem Fertigwalzen mit einer Endwalztemperatur oberhalb Ar3 mit einer mittleren Geschwindigkeit im Bereich von 30 bis 70 °C/s und ohne Unterbrechungen beschleunigt abgekühlt und dann bei einer Temperatur im Bereich von 350 bis 190 °C gehaspelt.Subsequently, the hot strip is cooled according to the invention immediately after finish rolling with a final rolling temperature above A r3 at an average speed in the range from 30 to 70 ° C./s and without interruptions and then coiled at a temperature in the range from 350 to 190 ° C. .
Erfindungsgemäß enthält die Bramme zusätzlich 0,01 bis 0,04 % Titan im stöchiometrischen Verhältnis zum Stickstoff, um bei der erfindungsgemäßen niedrigen Haspeltemperatur eine Verbesserung der Kaltumformbarkeit zu erzielen. Gleichzeitig wird damit eine Stickstoffalterung des fertiggewalzten Warmbandes bzw. der daraus hergestellten Bleche vermieden.According to the invention, the slab additionally contains 0.01 to 0.04% titanium in a stoichiometric ratio to nitrogen in order to achieve an improvement in the cold formability at the low coiling temperature according to the invention. At the same time, nitrogen aging of the finished rolled hot strip or the sheets produced therefrom is avoided.
Der wesentliche Vorteil des erfindungsgemäßen Verfahrens besteht darin, daß Warmband mit einem Zweiphasen-Gefüge aus feinkörnigem, globularem Ferrit (>80 %) und darin dispergierten Körnern aus Martensit auf herkömmlichen Warmbandstraßen mit der zugehörigen nachgeschalteten Kühlstrecke hergestellt werden kann. Ferner ermöglicht es das erfindungsgemäße Verfahren, auf bekannte Maßnahmen zur Beschleunigung der Ferritbildung und deren negative Auswirkungen, wie z.B. auf eine hohe Endverformung beim Warmwalzen und auf ein Fertigwalzen im Zweiphasen-Gebiet, zu verzichten. Dabei bedeuten eine hohe Endverformung unerwünschte hohe Walzkräfte sowie eine Verschlechterung der Bandebenheit und Bandgeometrie und ein Fertigwalzen im Zweiphasen-Gebiet ebenfalls hohe Walzkräfte, eine Verschlechterung der Kaltumformbarkeit und anisotrope mechanische Eigenschaften des fertiggewalzten Warmbandes.The main advantage of the method according to the invention is that hot strip with a two-phase structure made of fine-grained, globular ferrite (> 80%) and grains of martensite dispersed therein can be produced on conventional hot strip mills with the associated downstream cooling section. Furthermore, the method according to the invention enables known measures to accelerate ferrite formation and its negative effects, such as to dispense with a high final deformation during hot rolling and finish rolling in the two-phase area. A high final deformation means undesirable high rolling forces and a deterioration in strip flatness and strip geometry and finish rolling in the two-phase area also mean high rolling forces, a deterioration in cold formability and anisotropic mechanical properties of the hot rolled strip.
Im Vergleich zu den beiden aus der EP-B-19 193 und EP-A-72 867 vorbekannten Verfahren sind apparative Änderungen und vorrichtungsmäßige Ergänzungen der Kühlstrecke nicht erforderlich. Darüber hinaus ist es im Vergleich zu dem aus der EP-A-68 598 bekannten Verfahren auch nicht notwendig, die Temperatur, mit der das Warmwalzen begonnen wird, zu steuern und zuvor exakt einzustellen. Vielmehr kann bei dem erfindungsgemäßen Verfahren auch bei einer Temperatur > 1.250 °C mit dem Warmwalzen begonnen werden.In comparison to the two processes known from EP-B-19 193 and EP-A-72 867, changes in apparatus and additions to the cooling section in terms of apparatus are not necessary. In addition, in comparison to the method known from EP-A-68 598, it is also not necessary to control the temperature at which hot rolling is started and to set it precisely beforehand. Rather, in the method according to the invention, hot rolling can also be started at a temperature> 1,250 ° C.
Trotz des Hinweises in der EP-A-68 598, Seite 7, daß zur Einstellung des Zweiphasen-Gefüges ein Mn-Gehalt von mindestens 0,6 % erforderlich ist, hat sich überraschenderweise gezeigt, daß dies erfindungsgemäß auch mit einem reduzierten Mn-Gehalt, vorzugsweise im Bereich von 0,2 - 0,4 % möglich ist. Ein weiterer Vorteil des erfindungsgemäßen Verfahrens ist darin zu sehen, daß aufgrund des reduzierten Mn-Gehaltes die Herstellungkosten reduziert werden. Darüber hinaus bewirkt der erfindungsgemäß geringe Mn Gehalt in vorteilhafter Weise, daß sich praktisch keine gestreckten Sulfide (MnS) bilden, die üblicherweise bei hochfesten Stählen eine Verschlechterung der Kaltumformbarkeit, insbesondere in Querrichtung, verursachen. Aus diesem Grund kann beispielsweise bei dem erfindungsgemäßen Verfahren auf eine Absenkung des Schwefelgehaltes bei der Herstellung des Stahles verzichtet werden, um damit die Ausbildung gestreckter Sulfide bei höheren Mn-Gehalten zu steuern. Dies bedeutet aber eine Verringerung der Herstellungskosten der nach dem erfindungsgemäßen Verfahren erzeugten Warmbänder.Despite the note in EP-A-68 598, page 7, that an Mn content of at least 0.6% is required to set the two-phase structure, it has surprisingly been found that this also has a reduced Mn content according to the invention , preferably in the range of 0.2-0.4%. Another advantage of the method according to the invention is that the manufacturing costs are reduced due to the reduced Mn content. In addition, the low Mn content according to the invention advantageously has the effect that practically no stretched sulfides (MnS) form, which usually cause deterioration of the cold formability, in particular in the transverse direction, in high-strength steels. For this reason, a lowering of the sulfur content in the production of the steel can be dispensed with, for example, in the method according to the invention, in order to control the formation of elongated sulfides at higher Mn contents. However, this means a reduction in the production costs of the hot strips produced by the method according to the invention.
Dabei kann bei dem erfindungsgemäßen Verfahren im Gegensatz zu dem aus der EP-A-68 598 vorbekannten Verfahren auf den erhöhten Zusatz von Phosphor, der zur Versprödung führt, verzichtet werden. Der bevorzugte Phosphorgehalt ist auf 4 0,015 % begrenzt.In contrast to the method previously known from EP-A-68 598, the method according to the invention makes it possible to dispense with the increased addition of phosphorus, which leads to embrittlement. The preferred phosphorus content is limited to 4 0.015%.
Insgesamt kann mit Hilfe des erfindungsgemäßen Verfahrens Warmband mit einem Zweiphasen-Gefüge aus >80 % feinkörnigem, globularem Ferrit und Martensit und mit einem Streckgrenzenverhältnis < 0,70 hergestellt werden, das sich ohne Probleme schweißen läßt und sowohl in Längs- als auch in Querrichtung eine gute gleichmäßige Kaltumformbarkeit besitzt.Overall, hot strip with a two-phase structure made of> 80% fine-grained, globular ferrite and martensite and with a yield point ratio of <0.70 can be produced with the aid of the method according to the invention, which can be welded without problems and in both the longitudinal and transverse directions has good uniform cold formability.
Ein weiterer Vorteil des erfindungsgemäßen Verfahrens besteht darin, daß bei dem nach dem Verfahren hergestellten Warmband nach einer Verformung und anschließenden Anlaßbehandlung, beispielsweise durch das Einbrennen einer aufgetragenen Lackschicht, eine zusätzliche Streckgrenzensteigerung erreicht wird. Des weiteren ermöglicht der geringe Legierungsgehalt die Erzeugung von Warmband mit einem Zweiphasen-Gefüge mit Zugfestigkeiten von 500 bis 600 N/mm2, die insbesondere für die Fertigung von Teilen geeignet sind, die eine hohe Kaltumformbarkeit erfordern.Another advantage of the method according to the invention is that an additional increase in the yield strength is achieved in the hot strip produced by the method after deformation and subsequent tempering treatment, for example by burning in an applied lacquer layer. Furthermore, the low alloy content enables the production of hot strip with a two-phase structure with tensile strengths of 500 to 600 N / mm 2 , which are particularly suitable for the production of parts that require high cold formability.
Die Erfindung wird anhand der nachfolgenden Ausführungsbeispiele näher erläutert.The invention is explained in more detail using the following exemplary embodiments.
Stranggußbrammen mit den in Tabelle 1 angegebenen chemischen Zusammensetzungen A und B wurden zunächst auf eine Temperatur von ca. 1.250 °C erwärmt und durcherwärmt. Im Anschluß daran wurden sie bei einer Temperatur oberhalb Ar3 warm- und bis auf eine Enddicke d (s. Tabelle 2) fertiggewalzt. Dabei wurde die Endwalz- bzw. Fertigwalztemperatur möglichst dicht an Ar3 gelegt. Anschließend wurden die fertiggewalzten Bänder mit einer mittleren Geschwindigkeit im Bereich von 30 - 70 °C/s auf einer herkömmlichen der Warmbandstraße nachgeordneten Kühlstrecke ohne Unterbrechungen beschleunigt abgekühlt und bei den verschiedenen in Tabelle 2 angegebenen Haspeltemperaturen HT aufgewickelt. Es ergaben sich dabei die in Tabelle 2 zusammengestellten mechanischen Eigenschaften der fertiggewalzten Bleche.Continuous cast slabs with the chemical compositions A and B given in Table 1 were first heated to a temperature of approximately 1,250 ° C. and heated through. Subsequently, they were hot-rolled at a temperature above A r3 and finish- rolled to a final thickness d (see Table 2). The final rolling or finish rolling temperature was placed as close as possible to A r3 . Subsequently, the finished rolled strips were cooled with a medium speed in the range of 30-70 ° C./s on a conventional cooling section downstream of the hot strip mill without interruptions and wound up at the various reel temperatures HT shown in Table 2. The mechanical properties of the finished rolled sheets, as summarized in Table 2, resulted.
Die in Tabelle 2 angegebenen Werte verdeutlichen, daß bei den nach dem erfindungsgemäßen Verfahren hergestellten Bändernbzw. blechen ein Streckgrenzenverhältnis < 0,70 sowohl in Längsrichtung L als auch in Querrichtung Q erreicht werden konnte. Ferner ist der Tabelle 2 zu entnehmen, daß erfindungsgemäß eine Haspeltemperatur HT im Bereich von 350 - 190 °C eingehalten werden muß. Demgegenüber wird bei höheren Haspeltemperaturen das gewünschte ferritisch/martensitische Gefüge nicht erreicht, wie anhand der ausgeprägten Streckgrenze und des höheren Streckgrenzenverhältnisses der Proben A1 und B1 zu erkennen ist.The values given in Table 2 clarify that in the B produced by the process according to the invention. sheet metal has a yield point ratio of <0.70 both in the longitudinal direction L and in the transverse direction Q er could be enough. Table 2 also shows that, according to the invention, a reel temperature HT in the range from 350 to 190 ° C. must be maintained. In contrast, the desired ferritic / martensitic structure is not achieved at higher reel temperatures, as can be seen from the pronounced yield strength and the higher yield ratio of samples A1 and B1.
Darüber hinaus zeigt die Tabelle 2, daß die Haspeltemperatur HT vorzugsweise auf eine Temperatur oberhalb 200 °C einzustellen ist, weil sich bei einer niedrigeren Haspeltemperatur, s. Proben A3 und B3, das Streckgrenzenverhältnis wieder erhöht und die Bruchdehnung A5 zu noch schlechteren Werten hin abnimmt. Beides wirkt sich aber ungünstig auf die Kaltumformbarkeit des Warmbandes bzw. Bleches aus.In addition, Table 2 shows that the reel temperature HT should preferably be set to a temperature above 200 ° C, because at a lower reel temperature, s. Samples A3 and B3, the yield strength ratio increased again and the elongation at break A 5 decreased to even worse values. However, both have an unfavorable effect on the cold formability of the hot strip or sheet.
Ferner ergab eine künstlich durchgeführte Alterungsbehandlung bei 100 °C und ca. eine Stunde lang keine Veränderung der Streckgrenze. Andererseits wurde zum Beispiel bei den beiden Bändern bzw. Blechen A2 und B2 eine Streckgrenzensteigerung im Bereich von 40 - 80 N/mm2 nach einer Anlaßbehandlung bei ca. 170 °C und 20 Minuten lang ermittelt, nachdem die Bänder bzw. Bleche zuvor einer dreiprozentigen Vorverformung unterworfen wurden.
Claims (5)
dadurch gekennzeiehnet,
daß das Warmband
characterized by
that the hot strip
dadurch gekennzeichnet,
daß dem Stahl 0,06 bis 0,12 % C zugesetzt wird.2. The method according to claim 1,
characterized,
that 0.06 to 0.12% C is added to the steel.
dadurch gekennzeichnet,
daß der Phosphorgehalt auf ≤ 0,015 % begrenzt wird.3. The method according to claim 1 or 2,
characterized,
that the phosphorus content is limited to ≤ 0.015%.
dadurch gekennzeichnet,
daß dem Stahl zusätzlich 0,01 bis 0,04 % Titan im stöchiometrischen Verhältnis zum vorhandenen Stickstoff zugesetzt wird.4. The method according to any one of claims 1 to 3,
characterized,
that an additional 0.01 to 0.04% titanium is added to the steel in a stoichiometric ratio to the nitrogen present.
dadurch gekennzeichnet,
daß das Warmband bei einer Temperatur im Bereich von 20 bis 50 °C oberhalb Ar3 fertiggewalzt und nach der beschleunigten Abkühlung aus der Walzhitze bei einer Temperatur im Bereich von 330 bis 260 °C gehaspelt wird.5. The method according to any one of claims 1 to 4,
characterized,
that the hot strip is finish-rolled at a temperature in the range from 20 to 50 ° C. above A r3 and, after the accelerated cooling, is coiled out of the rolling heat at a temperature in the range from 330 to 260 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT85113944T ATE60624T1 (en) | 1984-11-08 | 1985-11-02 | PROCESS FOR PRODUCTION OF HOT STRIP WITH TWO-PHASE STRUCTURE. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3440752 | 1984-11-08 | ||
| DE3440752A DE3440752A1 (en) | 1984-11-08 | 1984-11-08 | METHOD FOR PRODUCING HOT TAPE WITH A TWO-PHASE TEXTURE |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0181583A2 true EP0181583A2 (en) | 1986-05-21 |
| EP0181583A3 EP0181583A3 (en) | 1988-11-17 |
| EP0181583B1 EP0181583B1 (en) | 1991-01-30 |
Family
ID=6249757
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP85113944A Expired - Lifetime EP0181583B1 (en) | 1984-11-08 | 1985-11-02 | Method of making a dual-phase hot-rolled steel strip |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4790889A (en) |
| EP (1) | EP0181583B1 (en) |
| JP (1) | JPH0676616B2 (en) |
| AT (1) | ATE60624T1 (en) |
| CA (1) | CA1269256A (en) |
| DE (2) | DE3440752A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998002589A1 (en) * | 1996-07-12 | 1998-01-22 | Thyssen Stahl Ag | Hot-rolled steel strip and method of making it |
| CZ304928B6 (en) * | 2000-12-06 | 2015-01-28 | Thyssen Krupp Stahl Ag | Process for producing steel strips by hot rolling |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3039842B2 (en) * | 1994-12-26 | 2000-05-08 | 川崎製鉄株式会社 | Hot-rolled and cold-rolled steel sheets for automobiles having excellent impact resistance and methods for producing them |
| EP0750049A1 (en) | 1995-06-16 | 1996-12-27 | Thyssen Stahl Aktiengesellschaft | Ferritic steel and its manufacture and use |
| AU756917B2 (en) * | 1996-06-07 | 2003-01-30 | Corus Staal B.V. | Process and device for producing a high-strength steel strip |
| NL1007739C2 (en) * | 1997-12-08 | 1999-06-09 | Hoogovens Staal Bv | Method and device for manufacturing a high strength steel strip. |
| NL1007731C2 (en) | 1997-12-08 | 1999-06-09 | Hoogovens Staal Bv | Method and device for manufacturing a ferritically rolled steel strip. |
| CA2297291C (en) * | 1999-02-09 | 2008-08-05 | Kawasaki Steel Corporation | High tensile strength hot-rolled steel sheet and method of producing the same |
| US20030041932A1 (en) * | 2000-02-23 | 2003-03-06 | Akio Tosaka | High tensile hot-rolled steel sheet having excellent strain aging hardening properties and method for producing the same |
| FI114484B (en) * | 2002-06-19 | 2004-10-29 | Rautaruukki Oyj | Hot rolled strip steel and its manufacturing process |
| DE10327383C5 (en) * | 2003-06-18 | 2013-10-17 | Aceria Compacta De Bizkaia S.A. | Plant for the production of hot strip with dual phase structure |
| SI1662011T1 (en) | 2004-11-24 | 2009-04-30 | Giovanni Arvedi | Hot rolled dual-phase steel strip having features of a cold rolled strip |
| CN109988970B (en) * | 2019-04-01 | 2021-08-31 | 山东钢铁集团日照有限公司 | Cold-rolled Q & P980 steel with different yield ratios and production method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4316753A (en) * | 1978-04-05 | 1982-02-23 | Nippon Steel Corporation | Method for producing low alloy hot rolled steel strip or sheet having high tensile strength, low yield ratio and excellent total elongation |
| EP0061503A1 (en) * | 1980-10-14 | 1982-10-06 | Kawasaki Steel Corporation | Process for manufacturing hot-rolled dual-phase high-tensile steel plate |
| EP0068598A2 (en) * | 1981-02-20 | 1983-01-05 | Kawasaki Steel Corporation | Dual phase-structured hot rolled high-tensile strength steel sheet and a method of producing the same |
| EP0072867A1 (en) * | 1981-02-20 | 1983-03-02 | Kawasaki Steel Corporation | Process for manufacturing high-tensile hot-rolled steel strip having a low yield ratio due to its mixed structure |
| EP0019193B1 (en) * | 1979-05-09 | 1984-03-21 | SSAB Svenskt Stal AB | A method of making steel strip with high strength and formability |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5818410B2 (en) * | 1977-12-06 | 1983-04-13 | 新日本製鐵株式会社 | Method for manufacturing high ductility low yield ratio hot rolled high tensile strength thin steel sheet |
| AU527097B2 (en) * | 1979-01-12 | 1983-02-17 | Nippon Steel Corporation | Artifically aged low yield to tensile strength ratio high strength steel sheet |
| JPS5927370B2 (en) * | 1980-07-05 | 1984-07-05 | 新日本製鐵株式会社 | High strength cold rolled steel plate for press working |
| JPS5893814A (en) * | 1981-11-30 | 1983-06-03 | Kawasaki Steel Corp | Production of low yield ratio and high tensile thick steel plate |
| US4466842A (en) * | 1982-04-03 | 1984-08-21 | Nippon Steel Corporation | Ferritic steel having ultra-fine grains and a method for producing the same |
-
1984
- 1984-11-08 DE DE3440752A patent/DE3440752A1/en active Granted
-
1985
- 1985-11-02 AT AT85113944T patent/ATE60624T1/en not_active IP Right Cessation
- 1985-11-02 DE DE8585113944T patent/DE3581591D1/en not_active Expired - Fee Related
- 1985-11-02 EP EP85113944A patent/EP0181583B1/en not_active Expired - Lifetime
- 1985-11-07 CA CA000494751A patent/CA1269256A/en not_active Expired - Fee Related
- 1985-11-08 JP JP60249086A patent/JPH0676616B2/en not_active Expired - Fee Related
-
1987
- 1987-05-19 US US07/051,892 patent/US4790889A/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4316753A (en) * | 1978-04-05 | 1982-02-23 | Nippon Steel Corporation | Method for producing low alloy hot rolled steel strip or sheet having high tensile strength, low yield ratio and excellent total elongation |
| EP0019193B1 (en) * | 1979-05-09 | 1984-03-21 | SSAB Svenskt Stal AB | A method of making steel strip with high strength and formability |
| EP0061503A1 (en) * | 1980-10-14 | 1982-10-06 | Kawasaki Steel Corporation | Process for manufacturing hot-rolled dual-phase high-tensile steel plate |
| EP0068598A2 (en) * | 1981-02-20 | 1983-01-05 | Kawasaki Steel Corporation | Dual phase-structured hot rolled high-tensile strength steel sheet and a method of producing the same |
| EP0072867A1 (en) * | 1981-02-20 | 1983-03-02 | Kawasaki Steel Corporation | Process for manufacturing high-tensile hot-rolled steel strip having a low yield ratio due to its mixed structure |
Non-Patent Citations (1)
| Title |
|---|
| CAHIERS D'INFORMATIONS TECHNIQUES DE LA REVUE DE METALLURGIE, Band 81, Nr. 12, Dezember 1984, Seiten 925-929, Paris, FR; A. TIVOLLE et al.: "Production endustrielle d'acier double-phase directement en sortie de train à bandes" * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998002589A1 (en) * | 1996-07-12 | 1998-01-22 | Thyssen Stahl Ag | Hot-rolled steel strip and method of making it |
| US6284063B1 (en) | 1996-07-12 | 2001-09-04 | Thyssen Stahl Ag | Hot-rolled steel strip and method of making it |
| CN1089811C (en) * | 1996-07-12 | 2002-08-28 | 蒂森钢铁股份公司 | Hot-rolled steel strip and method of making it |
| CZ304928B6 (en) * | 2000-12-06 | 2015-01-28 | Thyssen Krupp Stahl Ag | Process for producing steel strips by hot rolling |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3581591D1 (en) | 1991-03-07 |
| DE3440752C2 (en) | 1987-08-06 |
| EP0181583B1 (en) | 1991-01-30 |
| EP0181583A3 (en) | 1988-11-17 |
| ATE60624T1 (en) | 1991-02-15 |
| JPH0676616B2 (en) | 1994-09-28 |
| US4790889A (en) | 1988-12-13 |
| DE3440752A1 (en) | 1986-05-22 |
| CA1269256A (en) | 1990-05-22 |
| JPS61159535A (en) | 1986-07-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0619376B1 (en) | Method for manufacturing grain oriented electrical sheets with improved core loss | |
| DE60116477T2 (en) | WARM, COLD-ROLLED AND MELT-GALVANIZED STEEL PLATE WITH EXCELLENT RECEPTION BEHAVIOR | |
| DE2551791C3 (en) | Application of a process for the production of cold strips | |
| EP2690183B1 (en) | Hot-rolled steel flat product and method for its production | |
| DE3825634C2 (en) | Process for the production of hot baths or heavy plates | |
| WO2015144529A1 (en) | Method for producing a high-strength flat steel product | |
| DE3401406A1 (en) | Process for the manufacture of steel plates of high tensile strength | |
| DE3046941C2 (en) | A method of manufacturing a steel sheet having a two-phase structure | |
| EP0181583B1 (en) | Method of making a dual-phase hot-rolled steel strip | |
| EP2690184A1 (en) | Produit plat en acier laminé à froid et son procédé de fabrication | |
| DE2924167A1 (en) | METHOD OF MANUFACTURING COLD-ROLLED STEEL SHEET WITH DOUBLE-PHASE STRUCTURE | |
| EP0301228B1 (en) | Process for producing hot-rolled strip | |
| DE3134532C2 (en) | ||
| DE3221840C2 (en) | ||
| DE3000910C2 (en) | ||
| DE2133744A1 (en) | Controlled hot rolling procedure - for killed steels | |
| EP1398390B1 (en) | Steel with a very fine ferritic and martensitic microstructure having a high tensile strength | |
| EP0030309B1 (en) | Hot rolled strip or plate of denitrided steel and process for its production | |
| DE10130774C1 (en) | Production of a high strength cold-formed product comprises pre-casting a steel to a pre-material, hot rolling into a hot strip so that the micro-alloying elements remain dissolved, coiling, cold-forming to a product, and annealing | |
| DE3528782C2 (en) | ||
| EP1453984B1 (en) | Method for the production of hot strip or sheet from a micro-alloyed steel | |
| DE2316324C2 (en) | Process for the production of aging-resistant sheet steel | |
| DE2900022A1 (en) | METHOD FOR PRODUCING PROFILES | |
| EP1396550A1 (en) | Method for manufacturing hot strip | |
| DE3007560A1 (en) | METHOD FOR PRODUCING HOT-ROLLED SHEET WITH LOW STRETCH STRESS, HIGH TENSILE STRENGTH AND EXCELLENT SHAPING CAPACITY |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| AK | Designated contracting states |
Kind code of ref document: A2 Designated state(s): AT BE DE FR GB IT NL SE |
|
| PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
| AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): AT BE DE FR GB IT NL SE |
|
| 17P | Request for examination filed |
Effective date: 19881209 |
|
| 17Q | First examination report despatched |
Effective date: 19900201 |
|
| GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
| AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT BE DE FR GB IT NL SE |
|
| REF | Corresponds to: |
Ref document number: 60624 Country of ref document: AT Date of ref document: 19910215 Kind code of ref document: T |
|
| ET | Fr: translation filed | ||
| REF | Corresponds to: |
Ref document number: 3581591 Country of ref document: DE Date of ref document: 19910307 |
|
| GBT | Gb: translation of ep patent filed (gb section 77(6)(a)/1977) | ||
| ITF | It: translation for a ep patent filed |
Owner name: SOCIETA' ITALIANA BREVETTI S.P.A. |
|
| PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
| 26N | No opposition filed | ||
| EAL | Se: european patent in force in sweden |
Ref document number: 85113944.4 |
|
| REG | Reference to a national code |
Ref country code: GB Ref legal event code: IF02 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20021104 Year of fee payment: 18 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20021105 Year of fee payment: 18 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: AT Payment date: 20021108 Year of fee payment: 18 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: SE Payment date: 20021111 Year of fee payment: 18 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 20021112 Year of fee payment: 18 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20021128 Year of fee payment: 18 |
|
| PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: BE Payment date: 20021217 Year of fee payment: 18 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20031102 Ref country code: AT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20031102 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20031103 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: BE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20031130 |
|
| BERE | Be: lapsed |
Owner name: *THYSSEN STAHL A.G. Effective date: 20031130 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040601 |
|
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040602 |
|
| GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20031102 |
|
| EUG | Se: european patent has lapsed | ||
| PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040730 |
|
| NLV4 | Nl: lapsed or anulled due to non-payment of the annual fee |
Effective date: 20040601 |
|
| REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |