EP0413163B2 - Process and installation for producing thermomecanically treated rolled steel pieces - Google Patents
Process and installation for producing thermomecanically treated rolled steel pieces Download PDFInfo
- Publication number
- EP0413163B2 EP0413163B2 EP90113828A EP90113828A EP0413163B2 EP 0413163 B2 EP0413163 B2 EP 0413163B2 EP 90113828 A EP90113828 A EP 90113828A EP 90113828 A EP90113828 A EP 90113828A EP 0413163 B2 EP0413163 B2 EP 0413163B2
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- EP
- European Patent Office
- Prior art keywords
- temperature
- rolled steel
- rolling
- ferritic
- rolled
- 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.)
- Expired - Lifetime
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- 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 of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
Definitions
- the invention relates to a process for the production of thermomechanically treated steel rolling stock with a circular or annular cross section by means of a planetary cross-rolling mill, the rolling stock being reshaped in a specific temperature range.
- the austenite structure can therefore be set directly from the casting heat as in direct rolling, or in a preheating furnace from room temperature as in cold use or in an oven from an intermediate temperature as in hot use. In any case, however, prior to the actual thermomechanical treatment of the rolling stock, there is an austenite structure which either contains no or only a small proportion of germs or structural components of the phase which is stable at a lower temperature.
- the rolling stock is subjected to a powerful reshaping of its two opposite sides in a single wedge-shaped pass through the following incremental reduction steps at high speed.
- the reduction begins at the beginning of the rolling zone and is carried out along a wedge-shaped transition up to the final dimension of the rolling stock at the end of the rolling zone.
- a heat loss due to radiation and / or heat conduction is compensated for by deformation work in such a way that the slab is kept at an appropriate temperature within the rolling zone.
- the heat generated by the deformation work is used to reduce the previous heating.
- the temperature can be controlled, for example, by means of a controllable ratio between the feed speed and the speed of the sequence of incremental rolling passes.
- the slab can be heated up to a temperature above the range of blue brittleness, but below the active scaling temperatures. Structural cracks in the rolled product are prevented by applying strictly two-dimensional compressive forces.
- the rolling stock can be preheated to 400 to 500 ° Celsius or, in the case of ferrous magnetic metal, completely within the magnetic range, ie ⁇ A 1 , or the rolling temperature 816 ° C (1500 ° F ) in the case of low carbon steel. There is no information about the extent of a temperature rise when rolling steel.
- the object of the invention is to provide a method for the thermomechanical treatment of rolled steel with a circular or annular cross section, which enables the production of rolled products with a particularly favorable combination of strength and toughness properties.
- the conversion of the ferritic or ferritic-pearlitic initial structure into an austenitic or ferritic-austenitic structure takes place according to the invention under the influence of intensive forming and the associated heating of the rolling stock. Compared to external heating from the outside, when the rolling stock is formed in accordance with the invention, a particularly uniform heating takes place over the entire cross section of the rolling stock.
- the austenite that forms under these conditions is rich in germs of the phase that is resistant to low temperatures and has a particularly fine-grained structure.
- the subsequent reverse transformation of the deformed austenite leads to how practice has shown, to an extremely fine-grained structure of the structure with advantageous, significant improvement in strength and toughness properties and the associated substantial increase in the yield strength and impact strength of the rolled product.
- scaling can be suppressed to such an extent by tapping cold or not heated material up to Ac 1 temperature (Fe-C diagram) that, for example, when rolling steel pipes, the inner surface of the pipe is free of scale otherwise caused by scale Mistakes is.
- Ac 1 temperature Fe-C diagram
- this also results in improvements with regard to the surface roughness of the rolled product.
- the lower preheating temperature and the shorter dwell time at elevated temperatures mean that decarburization is significantly reduced compared to conventionally rolled steel material.
- the heating of the primary material which may have to be carried out can in this case remain limited to the head of the rolling stock and can take place in gas-heated preheating furnaces or also inductively.
- the piercing temperature of the rolling stock must be determined depending on the desired degree of forming.
- This system consists of a preheating unit (I) for the rolling stock, a high-forming unit (II) with a downstream cooling device (III) and a post-rolling or dimensioning mill (IV).
- the high-forming unit (II) the rolling stock is formed from steel with a circular or annular cross section according to the invention. This results in a significant increase in the yield strength and notched impact strength of the rolled product.
- a planetary cross-rolling mill is used as the high forming unit.
- accelerated cooling of the rolling stock with the aid of cooling media such as water can be carried out in the cooling device (III) downstream of the high-forming unit (II). Air or water-air mixture can be made.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Metal Rolling (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
Die Erfindung bezieht sich auf ein Verfahren zur Herstellung von thermomechanisch behandeltem Walzgut aus Stahl mit kreis- oder kreisringförmigem Querschnitt mittels eines Planeten-Schrägwalzwerks, wobei die Umformung des Walzgutes in einem bestimmten Temperaturbereich erfolgt.The invention relates to a process for the production of thermomechanically treated steel rolling stock with a circular or annular cross section by means of a planetary cross-rolling mill, the rolling stock being reshaped in a specific temperature range.
Es sind auf dem Gebiet der Herstellung von Walzprodukten aus Stahl verschiedene Verfahrenstechniken bekannt, und zwar das normalisierende Umformen aes Walzgutes und das thermomechanische Umformen des Walzgutes. Bei normalisierendem Umformen des Walzgutes findet die Endumformung im Bereich der Normalglühtemperatur mit vollständiger Rekristallisation des Austenits statt, während beim thermomechanischen Umformen des Walzgutes Temperaturbereicne für eine gezielte Umformrate eingehalten werden, bei denen der Austenit nicht oder nicht wesentlich rekristallisiert. Bei den bisherigen Verfahren zur thermomechanischen Behandlung von Walzgut aus Stahl wird als Gefügezustand der Zustand des Austenitgefüges vorausgesetzt, der vor der thermomechanischen Behandlung des Walzgutes vorgelegen hat. Die Einstellung des Austenitgefüges kann daher unmittelbar aus der Gießwärme erfolgen wie beim Direktwalzen, oder in einem Vorwärmofen von Raumtemperatur aus wie beim Kalteinsatz oder aber in einem Ofen von einer Zwischentemperatur aus wie beim Heißeinsatz. In jedem Fall liegt aber vor der eigentlichen thermomechanischen Behandlung des Walzgutes ein Austenitgefüge vor, das entweder keine oder nur geringe Anteile von Keimen oder Gefügeanteilen der bei niedrigerer Temperatur beständigen Phase enthält.Various process technologies are known in the field of the production of rolled products from steel, namely the normalizing forming of a rolling stock and the thermomechanical forming of the rolling stock. In the case of normalizing forming of the rolling stock, the final forming takes place in the area of the normalizing temperature with complete recrystallization of the austenite, while in the thermomechanical forming of the rolling stock temperature ranges are maintained for a specific forming rate at which the austenite does not recrystallize or does not recrystallize significantly. In the previous methods for the thermomechanical treatment of rolled steel, the state of the austenite structure that existed before the thermomechanical treatment of the rolled material is assumed as the structural state. The austenite structure can therefore be set directly from the casting heat as in direct rolling, or in a preheating furnace from room temperature as in cold use or in an oven from an intermediate temperature as in hot use. In any case, however, prior to the actual thermomechanical treatment of the rolling stock, there is an austenite structure which either contains no or only a small proportion of germs or structural components of the phase which is stable at a lower temperature.
Aus der US-A-2 710 550 ist ein Verfahren und eine Anlage für die Hochumformung von Walzgut bekannt. Das Dokument beschreibt ein für die Hochumformung geeignetes Planeten-Walzgerüst mit einer Hochumformeinheit mit nachgeschalterer Kühleinrichtung sowie einem Nachwalzwerk. Der eigentliche Walzvorgang erfolgt durch Eingriff einer endlosen Folge von Planetenrollen in das Walzgut, wobei diese das Material im Zustand einer in zwei Richtungen wirkenden Kompression verdichten und verformen, indem die Bramme einer großen Anzahl schnell aufeinanderfolgender kleiner Verformungsschritte ähnlich einem Schmiedeprozeß aus ihrer durch Gußerstarrung bedingten dendritischen Struktur verformt wird. Dabei erfolgt diese Verformung ohne Zugbeanspruchungen durch in kurzen Intervallen folgende reine Druckkräfte. Die Bramme wird mittels hoher Vorschubkräfte unter konstant langsamem Vorschub in die Walzzone eingeführt. Das Walzgut wird darin einer kraftvollen Umformung seiner beiden entgegengesetzten Seiten in einem einzigen keilförmigen Durchgang durch mit hoher Geschwindigkeit folgende inkrementelle Reduktionsschritte unterzogen. Die Reduktion beginnt am Anfang der Walzzone und wird entlang eines keilförmigen Übergangs bis zur Endabmessung des Walzgutes am Ende der Walzzone durchgeführt. Ein Wärmeverlust- durch Abstrahlung und/oder Wärmeleitung wird durch Verformungsarbeit derart ausgeglichen, daß die Bramme innerhalb der Walzzone bei zweckmäßiger Temperatur gehalten wird. Es wird die durch die Verformungsarbeit entstehende Wärme genutzt, um die vorhergehende Erwärmung zu reduzieren. Die Temperatur kann beispielsweise durch ein regelbares Verhältnis zwischen Zuführgeschwindigkeit und Geschwindigkeit der Folge von Inkrementeilen Walzstichen kontrolliert werden. Die Bramme kann bis zu einer Temperatur oberhalb des Bereichs der Blaubrüchigkeit, jedoch unterhalb der aktiven Verzunderungstemperaturen aufgeheizt werden. Durch Anwendung streng zweidimensionaler Druckkräfte werden Gefügerisse im Walzprodukt verhindert. Soweit dem Dokument Angaben über Temperaturbereiche beim Walzprozeß entnehmbar sind, kann das Walzgut auf 400 bis 500° Celsius bzw. im Fall von eisenhaltigem magnetischen Metall vollständig innerhalb des magnetischen Bereiches, d.h. <A1 vorgewärmt werden oder die Walztemperatur 816°C (1500°F) betragen im Fall von niedrig kohlenstoffhaltigem Stahl. Angaben über das Ausmaß eines Temperaturanstiegs beim Walzen von Stahl finden sich nicht.From US-A-2 710 550 a method and a plant for the high forming of rolling stock is known. The document describes a planetary roll stand suitable for high forming with a high forming unit with a downstream cooling device and a finishing mill. The actual rolling process takes place through the engagement of an endless sequence of planetary rollers in the rolling stock, these compressing and deforming the material in the state of a compression acting in two directions, in that the slab undergoes a large number of rapidly successive small deformation steps similar to a forging process from its dendritic cast rigidity Structure is deformed. This deformation takes place without tensile stresses by the following pure compressive forces at short intervals. The slab is introduced into the rolling zone by means of high feed forces with constant slow feed. The rolling stock is subjected to a powerful reshaping of its two opposite sides in a single wedge-shaped pass through the following incremental reduction steps at high speed. The reduction begins at the beginning of the rolling zone and is carried out along a wedge-shaped transition up to the final dimension of the rolling stock at the end of the rolling zone. A heat loss due to radiation and / or heat conduction is compensated for by deformation work in such a way that the slab is kept at an appropriate temperature within the rolling zone. The heat generated by the deformation work is used to reduce the previous heating. The temperature can be controlled, for example, by means of a controllable ratio between the feed speed and the speed of the sequence of incremental rolling passes. The slab can be heated up to a temperature above the range of blue brittleness, but below the active scaling temperatures. Structural cracks in the rolled product are prevented by applying strictly two-dimensional compressive forces. Insofar as the document provides information about temperature ranges during the rolling process, the rolling stock can be preheated to 400 to 500 ° Celsius or, in the case of ferrous magnetic metal, completely within the magnetic range, ie <A 1 , or the rolling temperature 816 ° C (1500 ° F ) in the case of low carbon steel. There is no information about the extent of a temperature rise when rolling steel.
Aufgabe der Erfindung ist es, ein Verfahren zur thermomechanischen Behandlung von Walzgut aus Stahl mit kreis- oder kreisringförmigem Querschnitt anzugeben, das die Herstellung von Walzprodukten mit einer besonders günstigen Kombination von Festigkeits- und Zähigkeitseigenschaften ermöglicht.The object of the invention is to provide a method for the thermomechanical treatment of rolled steel with a circular or annular cross section, which enables the production of rolled products with a particularly favorable combination of strength and toughness properties.
Diese Aufgabe wird mit der Erfindung gelöst gemäß Anspruch 1.This object is achieved with the invention according to claim 1.
Die Umwandlung des ferritschen oder ferritisch-perlitischen Ausgangsgefüges in ein austenitisches oder ferritisch-austenitisches Gefüge geschieht erfindungsgemäß unter dem Einfluß einer intensiven Umformung und der damit verbundenen Aufwärmung des Walzgutes. Gegenüber einer Fremderwärmung von außen stellt sich bei der Umformung des Walzgutes gemäß der Erfindung eine besonders gleichmäßige Durchwärmung über den gesamten Querschnitt des Walzgutes ein. Der sich unter diesen Bedingungen ausbildende Austenit ist reich an Keimen der bei niedriger Temperatur beständigen Phase und weist eine besonders feinkörnige Struktur auf. Die nachfolgende Rückumwandlung des verformten Austenits führt, wie die Praxis gezeigt hat, zu einer extrem feinkörniger Ausbildung des Gefüges mit vorteilhafter, erheblicher Verbesserung der Festigkeits- und Zähigkeitseigenschaften sowie der damit verbundenen, wesentlichen Erhöhung der Streckgrenzwerte und Kerbschlagzähigkeit des Walzproduktes.The conversion of the ferritic or ferritic-pearlitic initial structure into an austenitic or ferritic-austenitic structure takes place according to the invention under the influence of intensive forming and the associated heating of the rolling stock. Compared to external heating from the outside, when the rolling stock is formed in accordance with the invention, a particularly uniform heating takes place over the entire cross section of the rolling stock. The austenite that forms under these conditions is rich in germs of the phase that is resistant to low temperatures and has a particularly fine-grained structure. The subsequent reverse transformation of the deformed austenite leads to how practice has shown, to an extremely fine-grained structure of the structure with advantageous, significant improvement in strength and toughness properties and the associated substantial increase in the yield strength and impact strength of the rolled product.
Aus der deutschen Offenlegungsschrift 3810261 ist ein Verfahren zum Herstellen von Rohren. Stangen und Bändern bekannt, bei dem ein Barren in solcher Weise bearbeitet wird, daß die Temperatur des zu verarbeitenden Werkstoffes aufgrund des Einflusses des Widerstandes gegen die Verformung bis zum Rekristallisationsbereich ansteigt. Dieses bekannte Verfahren bezieht sich jedoch nicht auf die thermomechanische Behandlung von Walzgut aus Stahl, sondern auf die Herstellung von Rohren. Stangen und Bändern aus Nichteisenmetall.From the German laid-open specification 3810261 there is a method for producing pipes. Rods and strips are known, in which an ingot is processed in such a way that the temperature of the material to be processed rises to the recrystallization area due to the influence of the resistance to deformation. However, this known method does not relate to the thermomechanical treatment of rolled steel, but to the production of pipes. Non-ferrous metal bars and bands.
Ferner kann durch den Anstich von kaltem oder von nicht höher als bis zur Ac1 Temperatur (Fe-C-Diagramm) erwärmten Vormaterial eine Verzunderung in so starkem Maße unterdrückt werden, daß beispielsweise bei der Walzung von Stahlrohren die Rohrinnenfläche frei von ansonsten durch Zunder hervorgerufenen Fehlern ist. Insbesondere ergeben sich dadurch auch Verbesserungen in bezug auf die Oberflächenrauhigkeit des Walzproduktes. Im übrigen wird auch durch die geringere Vorwärmtemperatur und die kürzere Verweilzeit bei erhöhten Temperaturen die Entkohlung gegenüber herkömmlich gewalztem Material aus Stahl wesentlich reduziert. Die gegebenenfalls vorzunehmende Erwärmung des Vormaterials kann hierbei fallweise auf das Kopfstück des Walzgutes beschränkt bleiben und in gasbeheizten Vorwärmöfen oder auch induktiv erfolgen. Um bei der Endumformung des Walzgutes in den für die thermomechanische Walzung günstigsten Temperaturbereich zu kommen, muß jedoch die Anstich-Temperatur des Walzgutes in Abhängigkeit vom gewünschten Umformgrad festgelegt werden.Furthermore, scaling can be suppressed to such an extent by tapping cold or not heated material up to Ac 1 temperature (Fe-C diagram) that, for example, when rolling steel pipes, the inner surface of the pipe is free of scale otherwise caused by scale Mistakes is. In particular, this also results in improvements with regard to the surface roughness of the rolled product. Moreover, the lower preheating temperature and the shorter dwell time at elevated temperatures mean that decarburization is significantly reduced compared to conventionally rolled steel material. The heating of the primary material which may have to be carried out can in this case remain limited to the head of the rolling stock and can take place in gas-heated preheating furnaces or also inductively. In order to get the most favorable temperature range for the thermomechanical rolling during the final forming of the rolling stock, the piercing temperature of the rolling stock must be determined depending on the desired degree of forming.
Zur Durchführung des Verfahrens gemäß der Erfindung ist eine in der Zeichnung schematisch dargesteilte Anlage vorgesehen.To carry out the method according to the invention, a system is shown schematically in the drawing.
Diese Anlage besteht aus einer Vorwärmeinheit (I) für das Walzgut, einer Hochumformeinheit (II) mit nachgeschalteter Kühleinrichtung (III) und einem Nachwalzwerk bzw. Maßwaizwerk (IV). In der Hochumformeinheit (II) erfolgt die Umformung des Walzgutes aus Stahl mit kreis- oder kreisringförmigem Querschnitt gemäß der Erfindung. Hierdurch wird eine wesentliche Erhöhung der Streckgrenzwerte und der Kerbschlagzähigkeit des Walzproduktes erreicht. Als Hochumformeinheit kommt ein Planeten-Schrägwalzwerk zur Anwendung. Zur weiteren Verbesserung der Werkstoffeigenschaften kann in der der Hochumformeinheit (II) nachgeschalteten Kühleinrichtung (III) eine beschleunigte Kühlung des Walzgutes mit Hilfe von Kühlmedien wie Wasser. Luft oder Wasser-Luftgemisch vorgenommen werden.This system consists of a preheating unit (I) for the rolling stock, a high-forming unit (II) with a downstream cooling device (III) and a post-rolling or dimensioning mill (IV). In the high-forming unit (II), the rolling stock is formed from steel with a circular or annular cross section according to the invention. This results in a significant increase in the yield strength and notched impact strength of the rolled product. A planetary cross-rolling mill is used as the high forming unit. To further improve the material properties, accelerated cooling of the rolling stock with the aid of cooling media such as water can be carried out in the cooling device (III) downstream of the high-forming unit (II). Air or water-air mixture can be made.
Claims (1)
- Process for the production of thermomechanically treated rolled stock made of steel with a circular or annular cross section by means of a planetary cross rolling mill,
characterized in thata) the rolled stock is not heated to higher than AC1 temperature before its shaping and has a ferritic or ferritic-pearlitic initial structure,b) the shaping begins at a temperature corresponding to these initial structures - below the existence of an austenitic or ferritic-austenitic structure, andc) under the influence of the shaping of the rolled stock and the associated heating of the rolled stock, the temperature in the rolled stock is increased to just above or just below the conversion temperature AC3 of the ferritic or ferritic-pearlitic initial structure into an austenitic structure.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3926459 | 1989-08-10 | ||
| DE3926459A DE3926459A1 (en) | 1989-08-10 | 1989-08-10 | METHOD AND SYSTEM FOR THE PRODUCTION OF THERMOMECHANICALLY TREATED ROLLED STEEL |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0413163A1 EP0413163A1 (en) | 1991-02-20 |
| EP0413163B1 EP0413163B1 (en) | 1995-02-15 |
| EP0413163B2 true EP0413163B2 (en) | 1997-11-26 |
Family
ID=6386881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90113828A Expired - Lifetime EP0413163B2 (en) | 1989-08-10 | 1990-07-19 | Process and installation for producing thermomecanically treated rolled steel pieces |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0413163B2 (en) |
| JP (1) | JPH0372023A (en) |
| AT (1) | ATE118555T1 (en) |
| DE (2) | DE3926459A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19725434C2 (en) * | 1997-06-16 | 1999-08-19 | Schloemann Siemag Ag | Process for rolling hot wide strip in a CSP plant |
| DE19814223A1 (en) | 1998-03-31 | 1999-10-07 | Schloemann Siemag Ag | Process for the production of microalloyed structural steels |
| DE102006045871B4 (en) * | 2006-09-28 | 2010-01-28 | Rothe Erde Gmbh | Process for thermomechanical treatment of rings produced seamlessly on radial-axial ring rolling machines |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2710550A (en) * | 1954-06-07 | 1955-06-14 | Armzen Company | Planetary reducing apparatus and process |
| GB932462A (en) * | 1959-10-30 | 1963-07-24 | United States Steel Corp | Method of treating steel to produce a fine-grained structure |
| DE1272949B (en) * | 1962-10-17 | 1968-07-18 | Daido Steel Co Ltd | Process and device for the production of highly toothed steel sheets with a fine structure and non-directional properties |
| DE2205657A1 (en) * | 1972-02-07 | 1973-08-23 | Vni I Kt I Trubnoj Promy | PIPE MANUFACTURING PROCESS |
| DE2338391C3 (en) * | 1973-07-28 | 1978-08-24 | Fried. Krupp Huettenwerke Ag, 4630 Bochum | Method for producing strand-like round material from metallic material and device for carrying out the method |
| AT366298B (en) * | 1976-12-21 | 1982-03-25 | Schloemann Siemag Ag | ROLLING MILL FOR THE PRODUCTION OF SEAMLESS TUBES |
| FI77057C (en) * | 1987-03-26 | 1989-01-10 | Outokumpu Oy | FOERFARANDE FOER FRAMSTAELLNING AV ROER, STAENGER OCH BAND. |
-
1989
- 1989-08-10 DE DE3926459A patent/DE3926459A1/en not_active Withdrawn
-
1990
- 1990-07-19 DE DE59008465T patent/DE59008465D1/en not_active Expired - Fee Related
- 1990-07-19 AT AT90113828T patent/ATE118555T1/en not_active IP Right Cessation
- 1990-07-19 EP EP90113828A patent/EP0413163B2/en not_active Expired - Lifetime
- 1990-08-08 JP JP2208321A patent/JPH0372023A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0413163B1 (en) | 1995-02-15 |
| EP0413163A1 (en) | 1991-02-20 |
| DE59008465D1 (en) | 1995-03-23 |
| ATE118555T1 (en) | 1995-03-15 |
| JPH0372023A (en) | 1991-03-27 |
| DE3926459A1 (en) | 1991-02-14 |
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