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WO2021038108A1 - Method for the heat treatment of a primary steel product - Google Patents

Method for the heat treatment of a primary steel product Download PDF

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Publication number
WO2021038108A1
WO2021038108A1 PCT/EP2020/074237 EP2020074237W WO2021038108A1 WO 2021038108 A1 WO2021038108 A1 WO 2021038108A1 EP 2020074237 W EP2020074237 W EP 2020074237W WO 2021038108 A1 WO2021038108 A1 WO 2021038108A1
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WO
WIPO (PCT)
Prior art keywords
steel
product
heat treatment
furnace
temperature
Prior art date
Application number
PCT/EP2020/074237
Other languages
German (de)
French (fr)
Inventor
Ingo Schuster
Andreas Böttcher
Original Assignee
Sms Group Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sms Group Gmbh filed Critical Sms Group Gmbh
Publication of WO2021038108A1 publication Critical patent/WO2021038108A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/004—Heating the product
    • 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
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular fabrication or treatment of ingot or slab
    • 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
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/42—Induction heating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the invention relates to a method for the heat treatment of a steel intermediate product.
  • a specific temperature must be set for a slab in order to achieve optimal forming properties.
  • EP 2 035 587 B1 describes a method and an installation for the production of hot-rolled rolled stock from grain-oriented silicon steel on the basis of slabs.
  • the slab Before entering the rolling train, the slab is heated to a temperature of at least 1200 ° C and, for this purpose, passes through a preheating stage and an intensive heating stage. In the preheating stage, the slab temperature is set between 1000 ° C and 1100 ° C.
  • WO 2016/059 099 A1 discloses a method for producing a grain-oriented electrical steel strip from thin slabs. The thin slabs are heated to a temperature of> 1050 ° C, preferably a maximum of 1150 ° C should not be exceeded in the temperature control before the first piercing.
  • WO 2016/059 101 A1 describes a process with which a grain-oriented electrical steel strip can be produced.
  • a continuously cast thin slab is heated to a temperature> 1050 ° C in a hot rolling mill before the first piercing and annealed at a temperature ⁇ 1150 ° C to equalize the temperature.
  • the aim of temperature control in the publications is to set an optimal rolling temperature and to bring the aluminum nitrides precipitated during the solidification of the slab into solution in order to then selectively precipitate them during hot rolling.
  • the targeted overheating of the slab surface and the associated formation of liquid and / or partially liquid fayalite phases is accepted in these processes, since the dissolving of the aluminum nitrides and precipitation is essential for the properties of use.
  • the object of the invention is therefore to provide a method for the heat treatment of a steel preliminary product in which liquid and / or partially liquid slag on the surface of the slab is avoided.
  • the object of the invention is achieved by a method having the features of claim 1.
  • the heat treatment time in the furnace before the first piercing is set to a treatment time t B ⁇ -0.5 min / ° C ⁇ T z + 610 min, preferably t B ⁇ -0.45 min / ° C ⁇ T z + 510 min, limited.
  • the limitation of the treatment time in the heat treatment furnace means that the time required for the transport processes for the formation of liquid and / or partially liquid phases is not reached expire. It is essential to the invention that the surface temperature of the steel pre-product is set in a targeted manner and that the heat treatment times are not exceeded. Definitions:
  • Steel pre-product slab or billet from e.g. a continuous cast or
  • Ingot casting which is processed in a hot rolling mill to e.g.
  • Hot strip or bar are rolled, as well as their intermediate products in multi-stage hot rolling with intermediate heating
  • Thin slab slab with d ⁇ 150 mm
  • Pre-strip steel strip with d ⁇ 50 mm
  • the preliminary steel product is heated to the hot rolling temperature in the core by means of a heating device, preferably an induction heating device, before it enters the first hot rolling stand of the rolling step.
  • a heating device preferably an induction heating device
  • Induction devices make it possible to bring energy into the core of a steel pre-product within a short time without heating the surface too much. This avoids the formation of scale and the core rolling temperature can be easily adjusted.
  • the steel pre-product is moved with the aid of rollers as transport devices. Rollers reduce the risk of surface damage, especially in the case of the soft material according to the invention.
  • the steel preliminary product is moved with the aid of rollers as transport devices in the furnace during the heat treatment in the furnace. This avoids scoring or impressions on the surface of the steel pre-product.
  • the temperature on the surface of the steel precursor is, according to claim 6, during the heat treatment preferably a maximum of 20 K above the temperature at which liquid or partially liquid phases from oxidic binary and / or ternary compounds of the scale, preferably comprising Fe x O y , S1O2, AI2O3, form.
  • the formation temperatures of various relevant oxidic phases, in particular phases or mixed phases with Fe x O y , S1O2, Al2O3, are disclosed in the slag atlas. In addition to the mass transfer, this also inhibits the rate of formation of the liquid or partially liquid phases.
  • FIG. 1 shows a diagram with a heat treatment of a thin slab from the casting heat.
  • the core of the thin slab has a significantly higher temperature than the surface of the thin slab.
  • the target temperature is a homogeneous temperature of 1050 ° C both in the core and on the surface. After the temperature has been equalized, the core of the slab is heated to 1250 ° C by inductive heating before the first piercing in the roll stand.
  • FIG. 2 shows the temperature profile of a cold ingot cast slab up to the first tapping.
  • the ingot cast slab is slowly heated to a temperature below 1000 ° C. in two steps.
  • the preheating is followed by a heating curve to the target surface temperature of 1150 ° C. with a maximum holding time of 20 minutes. As a result, the surface of the slab cools down briefly.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Electromagnetism (AREA)
  • Manufacturing & Machinery (AREA)
  • Metal Rolling (AREA)
  • Manufacturing Of Steel Electrode Plates (AREA)

Abstract

The invention relates to a method for heat treating a primary steel product. By limiting the holding time to temperatures at which liquid or partially liquid scale phases form, the surface quality of a hot strip produced from the primary steel product is improved.

Description

Verfahren zur Wärmebehandlung eines Stahlvorproduktes Process for the heat treatment of a steel intermediate product
Gebiet: Area:
Die Erfindung betrifft ein Verfahren zur Wärmebehandlung eines Stahlvorproduktes. The invention relates to a method for the heat treatment of a steel intermediate product.
Stand der Technik: State of the art:
Vor dem Warmwalzen einer Bramme zu einem Warmband muss bei einer Bramme eine gezielte Temperatur eingestellt werden, um optimale Umformeigenschaften zu erreichen. Dazu werden entweder kalte Brammen aufgeheizt oder die Gießhitze der Brammen ausgenutzt um die Zieltemperatur zu erreichen oder zu halten. Before a slab is hot-rolled to form a hot strip, a specific temperature must be set for a slab in order to achieve optimal forming properties. For this purpose, either cold slabs are heated up or the casting heat of the slabs is used to reach or maintain the target temperature.
Bei den unterschiedlichen Verfahren entstehen dabei Temperaturdifferenzen zwischen dem Kern der Bramme und der Oberfläche der Bramme. Weiterhin entsteht auf der Oberfläche der Bramme FexOy-haltiger Zunder. Sofern der Stahl Silizium aufweist, kann dieser auch verzundert werden und mit dem FexOy zu Fayalit (Fe2(Si04) reagieren. Fayalit ist schon bei einer Temperatur von 1088°C flüssig und neigt dazu sich beispielsweise auf den Rollen eines Rollganges in der Walzstraße als Schicht unregelmäßig aufzubauen. Insbesondere bei auf Umformtemperatur weichen Stahlgüten, wie z.B. nicht kornorientierten Elektrobandstahlwerkstoffen, erzeugen diese Fayalit-Ablagerungen auf den Rollen Oberflächenbeschädigungen an der Bramme, die sich dann auf die Qualität des Warmbandes auswirken. In the different processes, temperature differences arise between the core of the slab and the surface of the slab. Furthermore, scale containing Fe x O y is formed on the surface of the slab. If the steel has silicon, it can also be scaled and react with the Fe x O y to form fayalite (Fe 2 (Si0 4 ). Fayalite is already liquid at a temperature of 1088 ° C and tends to, for example, on the rollers of a roller table In particular in the case of steel grades that are soft at the forming temperature, such as non-grain-oriented electrical steel materials, these fayalite deposits on the rollers cause surface damage on the slab, which then affects the quality of the hot strip.
Die EP 2 035 587 B1 beschreibt ein Verfahren und eine Anlage zur Herstellung von Warmband-Walzgut aus kornorientiertem Siliziumstahl auf der Basis von Brammen. Die Bramme wird vor Einlauf in die Walzstraße auf eine Temperatur von mindestens 1200°C aufgeheizt und durchläuft dazu eine Vorwärmstufe und eine Intensivheizstufe. In der Vorwärmstufe wird eine Temperatur der Bramme von 1000°C bis 1100°C eingestellt. Die WO 2016/059 099 A1 offenbart ein Verfahren zur Herstellung eines kornorientierten Elektrostahlbandes aus Dünnbrammen. Die Dünnbrammen werden auf eine Temperatur von > 1050°C aufgeheizt, wobei bevorzugt ein Maximum von 1150°C in der Temperaturführung vor dem ersten Anstich nicht überschritten werden soll. EP 2 035 587 B1 describes a method and an installation for the production of hot-rolled rolled stock from grain-oriented silicon steel on the basis of slabs. Before entering the rolling train, the slab is heated to a temperature of at least 1200 ° C and, for this purpose, passes through a preheating stage and an intensive heating stage. In the preheating stage, the slab temperature is set between 1000 ° C and 1100 ° C. WO 2016/059 099 A1 discloses a method for producing a grain-oriented electrical steel strip from thin slabs. The thin slabs are heated to a temperature of> 1050 ° C, preferably a maximum of 1150 ° C should not be exceeded in the temperature control before the first piercing.
In der WO 2016/059 101 A1 wird ein Prozess beschrieben mit dem ein kornorientierten Elektrostahlband erzeugt werden kann. Eine kontinuierlich gegossene Dünnbramme wird hier vor dem ersten Anstich in einer Warmwalzstraße auf eine Temperatur > 1050°C aufgeheizt und bei einer Temperatur < 1150°C zum Temperaturausgleich geglüht. Ziel der Temperaturführung in den Druckschriften ist das Einstellen einer optimalen Walztemperatur und das in Lösung Bringen der bei der Erstarrung der Bramme ausgeschiedenen Aluminiumnitride, um diese dann beim Warmwalzen gezielt auszuscheiden. Die gezielte Überhitzung der Brammenoberfläche und damit einhergehende Bildung von flüssigen und / oder Teilflüssigen Fayalit-Phasen wird bei diesen Prozessen hingenommen, da das in Lösung Bringen der Aluminiumnitride und Ausscheiden für die Gebrauchseigenschaften wesentlich ist. WO 2016/059 101 A1 describes a process with which a grain-oriented electrical steel strip can be produced. A continuously cast thin slab is heated to a temperature> 1050 ° C in a hot rolling mill before the first piercing and annealed at a temperature <1150 ° C to equalize the temperature. The aim of temperature control in the publications is to set an optimal rolling temperature and to bring the aluminum nitrides precipitated during the solidification of the slab into solution in order to then selectively precipitate them during hot rolling. The targeted overheating of the slab surface and the associated formation of liquid and / or partially liquid fayalite phases is accepted in these processes, since the dissolving of the aluminum nitrides and precipitation is essential for the properties of use.
Aufgabe der Erfindung: Object of the invention:
Aufgabe der Erfindung ist es daher ein Verfahren für die Wärmebehandlung eines Stahlvorproduktes bereitzustellen bei dem flüssige und / oder teilflüssige Schlacken auf der Oberfläche der Bramme vermieden werden. Erfindung: The object of the invention is therefore to provide a method for the heat treatment of a steel preliminary product in which liquid and / or partially liquid slag on the surface of the slab is avoided. Invention:
Die Aufgabe der Erfindung wird durch ein Verfahren mit den Merkmalen des Anspruchs 1 gelöst. Bei einer Zieltemperatur Tz auf der Oberfläche des Stahlvorproduktes wird die Wärmebehandlungszeit im Ofen vor dem ersten Anstich auf eine Behandlungszeit tB < -0,5 min/°C · Tz + 610 min, vorzugsweise tB < -0,45 min/°C · Tz + 510 min, begrenzt. Durch die Begrenzung der Behandlungszeit im Wärmebehandlungsofen wird die Zeitdauer unterschritten, die notwendig ist, damit die Transportvorgänge für die Bildung von flüssigen und / oder teilflüssige Phasen ablaufen. Erfindungswesentlich ist dabei, dass die Oberflächentemperatur des Stahlvorproduktes gezielt eingestellt wird und die Wärmebehandlungszeiten nicht überschritten werden. Definitionen: The object of the invention is achieved by a method having the features of claim 1. At a target temperature T z on the surface of the steel pre-product, the heat treatment time in the furnace before the first piercing is set to a treatment time t B <-0.5 min / ° C · T z + 610 min, preferably t B <-0.45 min / ° C · T z + 510 min, limited. The limitation of the treatment time in the heat treatment furnace means that the time required for the transport processes for the formation of liquid and / or partially liquid phases is not reached expire. It is essential to the invention that the surface temperature of the steel pre-product is set in a targeted manner and that the heat treatment times are not exceeded. Definitions:
Stahlvorprodukt: Bramme oder Knüppel aus z.B. einem Strangguss oderSteel pre-product: slab or billet from e.g. a continuous cast or
Blockguss, die in einem Warmwalzwerk zu einem z.B. Ingot casting, which is processed in a hot rolling mill to e.g.
Warmband oder Stab gewalzt werden, sowie deren Zwischenprodukte bei einem mehrstufigen Warmwalzen mit Zwischenerwärmung Dünnbramme: Bramme mit d < 150 mm Hot strip or bar are rolled, as well as their intermediate products in multi-stage hot rolling with intermediate heating Thin slab: slab with d <150 mm
Vorband: Stahlband mit d < 50 mm Pre-strip: steel strip with d <50 mm
Weitere bevorzugte Ausführungen des Verfahrens sind in den abhängigen Ansprüchen 2 bis 6 ausgeführt. Gemäß dem Anspruch 2 ist es bevorzugt, wenn das Stahlvorprodukt vor dem ersten Anstich im Walzgerüst entzundert wird. Auch im Erfindungsgemäßen Verfahren entstehen feste Zunderschichten auf der Oberfläche des Stahlvorproduktes. Das Entfernen der Zunderschichten vor dem Anstich verbessert die Oberflächenqualität des erzeugten Warmbandes. Further preferred embodiments of the method are set out in the dependent claims 2 to 6. According to claim 2, it is preferred if the steel precursor is descaled in the roll stand before the first piercing. In the method according to the invention, too, solid layers of scale arise on the surface of the steel precursor. The removal of the scale layers before the piercing improves the surface quality of the hot strip produced.
Das Stahlvorprodukt wird, gemäß dem Anspruch 3, vor Eintritt in das erste Warmwalzgerüst des Walzschrittes mittels einer Wärmeinrichtung, vorzugsweise einer Induktionswärmeinrichtung, auf die Warmwalztemperatur im Kern erwärmt. Induktionsvorrichtung ermöglichen es innerhalb kurzer Zeit Energie in den Kern eines Stahlvorproduktes zu bringen ohne die Oberfläche stark zu erwärmen. Dadurch wird eine Zunderbildung vermieden und eine Kernwalztemperatur wird einfach einstellbar. According to claim 3, the preliminary steel product is heated to the hot rolling temperature in the core by means of a heating device, preferably an induction heating device, before it enters the first hot rolling stand of the rolling step. Induction devices make it possible to bring energy into the core of a steel pre-product within a short time without heating the surface too much. This avoids the formation of scale and the core rolling temperature can be easily adjusted.
Gemäß dem Anspruch 4 ist es bevorzugt, wenn das Stahlvorprodukt mit Hilfe von Rollen als Transporteinrichtungen bewegt wird. Rollen reduzieren das Risiko für Oberflächenbeschädigungen, insbesondere bei dem erfindungsgemäßen weichen Werkstoff. Das Stahlvorprodukt wird, gemäß dem Anspruch 5, mit Hilfe von Rollen als Transporteinrichtungen im Ofen bei der Wärmebehandlung im Ofen bewegt. Dadurch werden Riefen oder Eindrücke auf der Oberfläche des Stahlvorproduktes vermieden. According to claim 4, it is preferred if the steel pre-product is moved with the aid of rollers as transport devices. Rollers reduce the risk of surface damage, especially in the case of the soft material according to the invention. According to claim 5, the steel preliminary product is moved with the aid of rollers as transport devices in the furnace during the heat treatment in the furnace. This avoids scoring or impressions on the surface of the steel pre-product.
Die Temperatur auf der Oberfläche des Stahlvorproduktes liegt, gemäß dem Anspruch 6, bei der Wärmebehandlung bevorzugt maximal 20 K oberhalb der Temperatur, bei dem sich flüssige oder teilflüssige Phasen aus oxidischen binären und / oder ternären Verbindungen des Zunders, vorzugsweise aufweisend FexOy, S1O2, AI2O3, bilden. Die Bildungstemperaturen von verschiedenen relevanten oxidischen Phasen, insbesondere Phasen bzw. Mischphasen mit FexOy, S1O2, AI2O3, sind im Schlackenatlas offenbart. Hierdurch wird neben dem Stofftransport auch die Bildungsgeschwindigkeit der flüssigen bzw. teilflüssigen Phasen gehemmt. The temperature on the surface of the steel precursor is, according to claim 6, during the heat treatment preferably a maximum of 20 K above the temperature at which liquid or partially liquid phases from oxidic binary and / or ternary compounds of the scale, preferably comprising Fe x O y , S1O2, AI2O3, form. The formation temperatures of various relevant oxidic phases, in particular phases or mixed phases with Fe x O y , S1O2, Al2O3, are disclosed in the slag atlas. In addition to the mass transfer, this also inhibits the rate of formation of the liquid or partially liquid phases.
Der Beschreibung der Erfindung sind zwei Figuren beigefügt: Two figures are attached to the description of the invention:
Figur 1 : Zeit-T emperatur-Diagramm Oberfläche Figure 1: Time-temperature diagram surface
Dünnbramme 1100°C Thin slab 1100 ° C
Figur 2: Zeit-T emperatur-Diagramm Oberfläche Dünnbramme 1160°C Figure 2: Time-temperature diagram surface thin slab 1160 ° C
Die Erfindung wird nachfolgend unter Bezugnahme auf die genannten Figuren in Form von Ausführungsbeispielen detailliert beschrieben. In allen Figuren sind gleiche technische Elemente mit gleichen Bezugszeichen bezeichnet. Figur 1 zeigt ein Diagramm mit einer Wärmebehandlung einer Dünnbramme aus der Gießhitze. Die Dünnbramme weist im Kern eine deutlich höhere Temperatur als an der Oberfläche der Dünnbramme auf. Zieltemperatur ist eine homogene Temperatur von 1050°C sowohl im Kern als auch auf der Oberfläche. Nach der Temperaturvergleichmäßigung wird der Kern der Bramme vor dem ersten Anstich im Walzgerüst durch eine induktive Erwärmung auf 1250°C erwärmt. The invention is described in detail below with reference to the figures mentioned in the form of exemplary embodiments. In all figures, the same technical elements are denoted by the same reference symbols. FIG. 1 shows a diagram with a heat treatment of a thin slab from the casting heat. The core of the thin slab has a significantly higher temperature than the surface of the thin slab. The target temperature is a homogeneous temperature of 1050 ° C both in the core and on the surface. After the temperature has been equalized, the core of the slab is heated to 1250 ° C by inductive heating before the first piercing in the roll stand.
Figur 2 stellt den Temperaturverlauf einer kalten Blockguss-Bramme bis zum ersten Anstich dar. Die Blockguss-Bramme wird langsam auf eine Temperatur unterhalb von 1000°C in zwei Schritte aufgeheizt. Nach der Vorwärmung folgt eine Aufheizkurve auf die Zieloberflächentemperatur von 1150°C mit einer maximalen Haltezeit von 20 min. Die derartig erwärmte Blockguss-Bramme wird in einem Hochdruckentzunderer von Oberflächenzunder befreit. Dadurch kühlt die Oberfläche der Bramme kurzfristig ab. FIG. 2 shows the temperature profile of a cold ingot cast slab up to the first tapping. The ingot cast slab is slowly heated to a temperature below 1000 ° C. in two steps. The preheating is followed by a heating curve to the target surface temperature of 1150 ° C. with a maximum holding time of 20 minutes. As a result, the surface of the slab cools down briefly.

Claims

Patentansprüche: Patent claims:
1. Verfahren zur Wärmebehandlung eines Stahlvorproduktes, insbesondere zur Herstellung eines nicht kornorientierten Elektrostahlbandes, aufweisend die Legierungsbestandteile (in Gew.-%) Si > 1 ,8 % AI > 0,5 % C < 50 ppm N < 40 ppm S < 30 ppm Mn 0,060 % - 0,500 % Cu < 0,100 % Ni < 0,100 % Mo < 0,100 % Cr < 0,100 % Sn < 0,100 % Sb < 0,100 % Si + AI < 4,6 % sowie Rest Eisen (Fe) und unvermeidbare Verunreinigungen, in einem Ofen in einem Walzwerk vor einem Warmwalzschritt, wobei bei der Wärmebehandlung in dem Ofen Zunder auf den Oberflächen des Stahlvorproduktes in Form von oxidischen Verbindungen entsteht und das Stahlvorprodukt mit Hilfe von Transportvorrichtungen im Ofen sowie zwischen dem Ofen und dem ersten Anstich in einem Walzgerüst des Warmwalzschrittes bewegt wird, dadurch gekennzeichnet, dass bei einer Zieltemperatur Tz auf der Oberfläche des Stahlvorproduktes die Wärmebehandlungszeit im Ofen vor dem ersten Anstich auf eine Behandlungszeit tB < -0,5 min/°C · Tz + 610 min, vorzugsweise tB < - 0,45 min/°C · Tz + 510 min, begrenzt wird. 1. Process for the heat treatment of a steel intermediate product, in particular for the production of a non-grain-oriented electrical steel strip, comprising the alloy components (in% by weight) Si> 1.8% Al> 0.5% C <50 ppm N <40 ppm S <30 ppm Mn 0.060% - 0.500% Cu <0.100% Ni <0.100% Mo <0.100% Cr <0.100% Sn <0.100% Sb <0.100% Si + AI <4.6% as well as the remainder iron (Fe) and unavoidable impurities, in one Furnace in a rolling mill before a hot rolling step, with the heat treatment in the furnace producing scale on the surfaces of the steel pre-product in the form of oxidic compounds and moving the steel pre-product with the help of transport devices in the furnace and between the furnace and the first pass in a rolling stand of the hot rolling step is, characterized in that at a target temperature T z on the surface of the steel pre-product, the heat treatment time in the furnace before the first tapping to a treatment time t B <-0.5 min / ° C · T z + 610 min, preferably t B <- 0.45 min / ° C · T z + 510 min, is limited.
2. Verfahren nach einem der vorangegangenen Ansprüche, dadurch gekennzeichnet, dass das Stahlvorprodukt vor dem ersten Anstich im Walzgerüst entzundert wird. 2. The method according to any one of the preceding claims, characterized in that the steel pre-product is descaled in the roll stand before the first piercing.
3. Verfahren nach einem der vorangegangenen Ansprüche, dadurch gekennzeichnet, dass das Stahlvorprodukt vor Eintritt in das erste Warmwalzgerüst des Walzschrittes mittels einer Wärmeinrichtung, vorzugsweise einer Induktionswärmeinrichtung, auf die Warmwalztemperatur im Kern erwärmt wird. 3. The method according to any one of the preceding claims, characterized in that the steel precursor is heated to the hot rolling temperature in the core by means of a heating device, preferably an induction heating device, before entering the first hot rolling stand of the rolling step.
4. Verfahren nach einem der vorangegangenen Ansprüche, dadurch gekennzeichnet, dass das Stahlvorprodukt mit Hilfe von Rollen als Transporteinrichtungen bewegt wird. 4. The method according to any one of the preceding claims, characterized in that the steel pre-product is moved with the aid of rollers as transport devices.
5. Verfahren nach einem der vorangegangenen Ansprüche, dadurch gekennzeichnet, dass das Stahlvorprodukt mit Hilfe von Rollen als Transporteinrichtungen im Ofen bei der Wärmebehandlung im Ofen bewegt wird. 5. The method according to any one of the preceding claims, characterized in that the steel pre-product is moved with the aid of rollers as transport devices in the furnace during the heat treatment in the furnace.
6. Verfahren nach einem der vorangegangenen Ansprüche, dadurch gekennzeichnet, dass die Temperatur auf der Oberfläche des Stahlvorproduktes bei der Wärmebehandlung maximal 20 K oberhalb der Temperatur liegt, bei dem sich flüssige oder teilflüssige Phasen aus oxidischen binären und / oder ternären Verbindungen des Zunders, vorzugsweise aufweisend FexOy, S1O2, AI2O3, bilden. 6. The method according to any one of the preceding claims, characterized in that the temperature on the surface of the steel precursor during the heat treatment is a maximum of 20 K above the temperature at which liquid or partially liquid phases from oxidic binary and / or ternary compounds of the scale, preferably having FexOy, S1O2, AI2O3, form.
PCT/EP2020/074237 2019-08-30 2020-08-31 Method for the heat treatment of a primary steel product WO2021038108A1 (en)

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WO2016059099A1 (en) 2014-10-15 2016-04-21 Sms Group Gmbh Process for producing grain-oriented electrical steel strip and grain-oriented electrical steel strip obtained according to said process
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Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0377734A1 (en) * 1987-03-11 1990-07-18 Nippon Kokan Kabushiki Kaisha PRODUCTION OF NON-ORIENTED HIGH-Si STEEL SHEET
US4898628A (en) * 1989-01-19 1990-02-06 Armco Advanced Materials Corporation Hot working method for producing grain oriented silicon steel with improved glass film formation
US6280542B1 (en) * 1996-06-07 2001-08-28 Corus Technology Bv Method and apparatus for the manufacture of a steel strip
DE102007005015A1 (en) * 2006-06-26 2008-01-03 Sms Demag Ag Process and plant for the production of hot rolled strip of silicon steel based on thin slabs
EP2035587B1 (en) 2006-06-26 2017-02-01 SMS group GmbH A method and a system for producing hot-rolled strip silicon steel based on thin slabs
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