DE102006057858A1 - Continuous casting method for steels which are highly alloyed and have high carbon content comprises casting melt on to strip of unalloyed, low-carbon steel whose edges are brought together around it and welded together - Google Patents

Abstract

Continuous casting method for steels which are highly alloyed and/or have a high carbon content comprises casting the melt (G) on to a steel strip (B) whose edges (H) are brought together around it and welded together. The strip is made from unalloyed, low-carbon steel and is removed before further processing of the cast product.

Description

The This invention relates to continuous casting (high) alloying processes and / or high carbon steels.

• – Nutzung teuerer Schutzgasmedien (Stickstoff, Edelgase, Endogas, Vakuum) bei Wärmebehandlung und bei Warmwalzen – wegen niedriger Schmelztemperaturen der Oxiden vieler Legierungselemente (z. B., T° M₀O₃ = 795°C, T° V₂O₅ = 658°C) sowie wegen der Entkohlung, Aufkohlung, Oxidierung der Gussoberfläche;
• – kleinere Querschnittsabnahmen, langsame Geschwindigkeit der Erwärmung und der Abkühlung wegen der Gefahr der Erscheinung von Oberflächenrissen;
• – niedrige Haltbarkeit verformender Werkzeuge wegen der Neigung Cr-Ni-haltiger Stähle zum Anhaften und hoher Abriebwirkung der Oxide und der Karbide von Legierungselementen;
• – Verluste von Legierungselementen mit zu entfernendem Metall bei Bearbeitung der Gussoberflächen: beim Putzen des Gießlings, bei Beizen von Bunten des Gussprodukts und bei Spanbearbeitung der Stangen seiner Oberflächen;
• – längere Beizzeit und der Nutzung einiger teueren Beizlösungen für unterschiedliche Stähle, wobei diese Beizlösungen sich nicht regenerieren lassen oder niedrige Wiedernutzbarkeit haben sowie große Anzahl der Zwischenglühen bei Verarbeitung zu kleinerem Querschnitt.

The following difficulties in processing the continuous casting products from the alloyed and high-carbon steels are known:

• - Use of expensive inert gas media (nitrogen, noble gases, endogas, vacuum) during heat treatment and hot rolling - due to low melting temperatures of the oxides of many alloying elements (eg, T ° M ₀ O ₃ = 795 ° C, T ° V ₂ O ₅ = 658 ° C) as well as decarburization, carburizing, oxidation of the casting surface;
• - smaller cross-sectional decreases, slow rate of heating and cooling due to the risk of surface cracking;
• Low durability of deforming tools due to the tendency of Cr-Ni containing steels to adhere and high abrasive action of the oxides and carbides of alloying elements;
• - Loss of alloying elements with metal to be removed during machining of the casting surfaces: when brushing the casting, when pickling multicolored of the cast product and when machining the bars of its surfaces;
• - longer pickling time and the use of some expensive pickling solutions for different steels, these pickling solutions can not be regenerated or have low recoverability and large number of intermediate annealing when processing to smaller cross-section.

Methods are provided which are presumed to produce the composite cast blocks, the surface of the blocks being of high alloy steel, and the core of unalloyed steel being:
patents WO: 95/26241 . EP: 0 852 165 .
from Germany: 3 440 237 . 3 440 235 . 3 440 234 . 3 406 730 . 3 032 789 . 1 508 876 . 742 180 . 69 909 332 .
from USA: 5 077 094 . 4,945,974 . 4 529 628 . 4,326,579 . 4,323,419 . 4,321,289 . 4,22978 . 4,326,579 . 4,323,419 . 4,321,289 . 4,224,978 . 4 177 326 . 4,171,394 . 4,152,471 . 3,971,123 . 3 479 210 . 3,457,984 . 3 349 830 . 3,201,275 . 2 931 082 . 2 055 980 .
from Franconia: 884 516 , from Switzerland: 203 489 ,

The closest idea is a process for producing coated continuous casting products according to the cited patent EP 0 852 165 , It involves filling a moving mold envelope with a melt, wherein the solidus temperature of the cladding (high-alloy steel) is lower than (or equal to) the solidus temperature of the melt (of unalloyed steel).

• – erwähnte Schwierigkeiten der Verarbeitung der legierten Stähle,
• – Eigenschaften der Stranggussprodukte im Nahtbereich der Umhüllung sind wesentlich schlechter;
• – stärkere Abkühlung der Umhüllung zwecks Nichtzulassung ihres Durchschmelzens, weil ihre Solidustemperatur kleiner als Solidustemperatur der Schmelze.

The shortcomings of this procedure:

• - mentioned difficulties of processing of alloyed steels,
• - properties of the continuous casting in the seam area of the envelope are much worse;
• Greater cooling of the coating for the purpose of preventing its melting, because its solidus temperature is lower than the solidus temperature of the melt.

technical The result of the proposed idea finds expression in the increase of productivity of processing of continuous casting products and in the improvement of quality their surfaces.

This result is achieved by producing the continuous casting product in the following way:
the steel melt filling is carried out in a continuously formed, movable, closed mold sheath, their formation is carried out at least from a steel band, strip edges (strip edges) are subjected to continuous welding, wherein the envelope (band / bands) of unalloyed (microalloyed) low-carbon steel is produced, and the melt of (high) alloyed and / or high carbon steel is carried out, wherein the casing is subjected to the removal in subsequent processing of the cast product.

• – am Ende dieser Verarbeitung: in der Beizlösung – zum Bundmaterial oder
• – nach dieser Verarbeitung: bei der Spanbearbeitung – zum Stabmaterial oder in der Beizlösung – zu großen Teilen

und wird bestimmt überhaupt mit dem Verhältnis zwischen Umhüllungsbanddicke und Maßen von Querschnittsfläche sowie mit der Zundertiefe.This removal takes place

• - at the end of this processing: in the pickling solution - to the Bundmaterial or
• - after processing: in chip processing - to bar material or in the pickling solution - in large parts

and is determined at all with the relationship between envelope tape thickness and dimensions of cross-sectional area as well as with the scale depth.

there the pickling solution contains stain inhibitor from Fe not - for the purpose of complete removal of the envelope.

To the Example, this distance leads you

• - During the cold deformation: in the last pickling of the continuous casting product in a technological series, while the pickling is carried out in the cheapest, regenerable H ₂ SO ₄ solution, z. B. before last drawing (rolling) of a drawn (rolled) bundle wire (bands) to a smaller diameter (profile);
• During chip machining of the bars: z. B., when turning them are not less than 2.5 mm for chip removal exposed to scale, decarburization, surface defects and to remove geometric variations.

The products manufactured according to this idea can be stained in the conventional H ₂ SO ₄ solution prior to the last cold forming and covered with the cheapest sub-lubricating coating - phosphate.

The Welding the strip contour - power transmission from power source to longitudinally welded hollow body - takes place either directly through current-conducting contact or eddy currents (high-frequency welding). When there is a seam burr, its removal is carried out.

There Solidus temperature of the band higher than the solidus temperature of the melt is, not allowing possible meltdown (breakthrough) serving at lower intensity of cooling off Gießling attains, - it enables productivity of To increase continuous casting. Minimum intensity of Cooling of the envelope becomes with inadmissibility limited by their melting.

At the Beginning of the melt filling is a front contour on the closed enclosure necessary.

The Durability of the tools for shaping to get cast product will be higher because the wrapping is made of soft Steel with low content of carbides, and the absence of Ni and Cr in the steel eliminates sticking to the tool.

warming The products manufactured according to this idea are in the cheapest open atmosphere - Exogas executed.

The can according to proposed idea produced continuous casting products to deform with high intensity, to warm and cool thanks to high plasticity and heat conduction of cladding material - unalloyed low carbon Steel.

• 1. Abwickeln eines Bands mit der Bildung seines Vorrats zur Gewährleistung des ununterbrochenen Schweißens; das Band: 1 mm-Dicke und 500 mm-Breite aus unlegiertem Stahl mit Gehalt an C ≤ 0,08%.
• 2. Bearbeitung der Bandeskanten zum Schweißen.
• 3. Folgegemäßes Formen des Bandes zum Zylinder.
• 4. Widerstandsschweißen der Bandkanten mit Herausbildung einer geschlossenen ringförmigen Hülle mit Außendurchmesser 160 mm.
• 5. Gießen des Stahlschmelzens mit Gehalt an Cr = 18%, Ni = 10%, C = 0,10% in die gebildete geschweißte geschlossene gekühlte Umhüllung.
• 6. Entfernung des Schweißgrats.
• 7. Das Walzen bekommenen Stranggussblocks mit 75%-Gesamtvorwalzen (30 + 25 + 20)% in 3 Walzengerüsten.

An example of the realization of proposed idea:

• 1. unwinding a ribbon with the formation of its stock to ensure uninterrupted welding; the strip: 1 mm thick and 500 mm wide, carbon steel grading C ≤ 0.08%.
• 2. Processing of the band edges for welding.
• 3. Subsequent shaping of the band to the cylinder.
• 4. Resistance welding of the strip edges with formation of a closed annular shell with an outer diameter of 160 mm.
• 5. Casting the steel melt containing Cr = 18%, Ni = 10%, C = 0.10% into the formed welded closed cooled cladding.
• 6. Removal of the weld burr.
• 7. The rolling continuously cast block with 75% total roughing (30 + 25 + 20)% in 3 roll stands.

On the 1 - 3 Three production processes for high-alloy steels are presented.

you Manufacturing principle is based on continuous transformation of the / Bands / strips made of a non-alloyed low-carbon steel by his / her molding rolls to a closed hollow slot body. The edges of this slot body are welded seam / welds connected.

On the 1 is a manufacturing process of round continuous casting products; on the 2 and 3 are two manufacturing processes of rectangular continuous casting products.

On the 1 - 3 A (high-alloyed) molten steel S flows from an intermediate container Z into a hollow body H, which is provided with pressure rolls / roll bending machines from a strip B (FIG. 1 ) or two bands B ( 2 - 3 ) (made of an unalloyed low-carbon steel) is formed. Slit body edges R should be prepared in such a way that they can be stapled without difficulty after forming and welded with roller electrodes RE. In the cooling chambers KK liquid casting strand G is sprayed with water and solidified. The material that is superfluous after welding must be removed with cut-off rollers AR.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 95/26241 [0003]
• - EP 0852165 [0003, 0004]
• - EP 3440237 [0003]
• - EP 3440235 [0003]
• - EP 3440234 [0003]
• - EP 3406730 [0003]
• - DE 3032789 [0003]
• - DE 1508876 [0003]
• - DE 742180 [0003]
• - DE 69909332 [0003]
• - US 5077094 [0003]
• US 4945974 [0003]
• US 4529628 [0003]
• US 4326579 [0003, 0003]
• US 4323419 [0003, 0003]
• US 4321289 [0003, 0003]
• - US 422978 [0003]
• - US 4224978 [0003]
• - US 4177326 [0003]
• - US 4171394 [0003]
• - US 4152471 [0003]
• US 3971123 [0003]
• - US 3479210 [0003]
• US 3,457,984 [0003]
• - US 3349830 [0003]
• US 3201275 [0003]
• US 2931082 [0003]
• - US 2055980 [0003]
• FR 884516 [0003]
• - SZ 203489 [0003]

Claims (1)

High-alloyed and / or high-carbon steels include molten steel filler into a continuously formed, movable closed casing, their formation is carried out at least from a steel band, and strip edges are subjected to continuous welding, characterized in that the melt is out (high) alloyed and / or high carbon steel is produced and the unalloyed low carbon steel cladding is produced, the cladding being subject to removal upon subsequent processing of the cast product.