CA2229750A1 - Method and plant for producing sheathed continuously cast products - Google Patents

Method and plant for producing sheathed continuously cast products Download PDF

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Publication number
CA2229750A1
CA2229750A1 CA002229750A CA2229750A CA2229750A1 CA 2229750 A1 CA2229750 A1 CA 2229750A1 CA 002229750 A CA002229750 A CA 002229750A CA 2229750 A CA2229750 A CA 2229750A CA 2229750 A1 CA2229750 A1 CA 2229750A1
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CA
Canada
Prior art keywords
sheathing
mold
metal
casting
melt
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.)
Abandoned
Application number
CA002229750A
Other languages
French (fr)
Inventor
Fritz-Peter Pleschiutschnigg
Michael Vonderbank
Joachim Schwellenbach
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SMS Siemag AG
Original Assignee
SMS Schloemann Siemag AG
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
Priority to DE19651324A priority Critical patent/DE19651324C2/en
Priority to EP97119937A priority patent/EP0852165A3/en
Priority to JP10022361A priority patent/JPH11221651A/en
Priority to BR9806394-4A priority patent/BR9806394A/en
Application filed by SMS Schloemann Siemag AG filed Critical SMS Schloemann Siemag AG
Priority to CA002229750A priority patent/CA2229750A1/en
Priority to AU55378/98A priority patent/AU5537898A/en
Priority to ZA981366A priority patent/ZA981366B/en
Publication of CA2229750A1 publication Critical patent/CA2229750A1/en
Abandoned legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/008Continuous casting of metals, i.e. casting in indefinite lengths of clad ingots, i.e. the molten metal being cast against a continuous strip forming part of the cast product
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0622Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)

Abstract

A method of producing thin metal strip, wherein the liquid molten metal is contacted with and welded to a flat metal product, preferably a hot strip of steel, and a plant for carrying out the method using an oscillating mold, i.e.) stationary mold, or a travelling mold, preferably a two-roller casting unit, in which the flat metal product of hot strip is continuously introduced in such a way that it surrounds the entering molten metal on all sides and is discharged through a delivery system. The solidus temperature of the metal sheathing is always smaller than or equal to the solidus temperature of the molten metal. In the mold, the sheathing material is guided along at least one of the wall surfaces of the mold.

Description

METHOD AND PLANT FOR PRODUCING SHEATHED CONTINUOUSLY CAST PRODUCTS
BACKGRODND OF THE INVENTION
1. Field of the Invention The present invention relates to a method of producing thin metal strip, wherein the liquid molten metal is contacted with and welded to a flat metal product, preferably a hot strip of steel. The present invention also relates to a plant for carrying out the method by means of an oscillating mold, i.e., stationary mold, or a travelling mold, preferably a two-roller casting unit, in which the flat metal product of hot strip is continuously introduced in such a way that it surrounds the entering molten metal on all sides and is discharged through a delivery s~~stem.
s;. Description of the Related Art Flat products having thicknesses of less than 2mm are to date primarily produced by rolling hot strip which can then also be cold rolled down to thicknesses of 0.2mm. The requirements with respects to sectional dimensions and planarity of the cold strip must already be adjusted by percentage during the hot rolling process because a percentage correction of the accuracy to dimension is no longer possible during the cold rolling process. ~~tarting at a width/thickness ratio of about 100/1, the resistance to flow in the roller gap becomes practically infinitely large in the width direction, so that a percentage correction of sectional dimension and planarity is no longer possible. For this reason, developments of casting technologies which attempt to realize, for example, sizes with widths of greater than 1,OOOmm and thicknesses of less than lOmm have up to now essentially not gone past the status of a semi-production unit.
When casting thin sizes with an oscillating mold with the formation of a slag film thickness inherent in the system and with the prerequisite of the same production as it is achieved in a conventional slab unit, the main problem is that, corresponding to the lowering of the casting thickness and the increase of the casting speed, the surface area produced per unit of time increases x>y a multiple and the slag film thickness decreases simultaneously. Also increasing at the same time are the solidification heat released per unit of time and, thus, the heat flux in the mold.
Fig. 1. of the drawing illustrates the resulting heat flux in dependence on the casting thickness and the casting speed. For example, if' the critical heat flux of a conventionally produced slab having a thickness of 200mm and being cast with lm/min is about 1MW/m2, the lowering of the casting thickness to, for example, 50mm while simultaneously increasing the casting speed to 6m/min results in an increase of the heat flux to 2.8MW/m2.
Corresponding to the shrinkage index, the danger of the occurrence of longitudinal cracks increases to 2.8 from the standardized value 1 in the case of a standard slab, i.e., the susceptibility to longitudinal cracks is 2.8 times greater than in a standard slab with the width being equal.
The limit analysis of the partial illustrations of Fig. 1 exhibits a minimum relative slag film thickness of 0.001 or 0.02mm and essentially reflects the conditions when casting without casting powder. The integral heat flux reaches a value of about 5MW/m2 and can also be found in billet plants in which casting is carried without casting powder or casting slag.
Similar conditions with respect to the heat flux also exist when casting strip with travelling molds. The lack of slag also results in these processes in heat fluxes on the level of the limit analysis.
When transferring these results to strip plants, the following becomes clear:

1. The slag-free casting results in a significantly higher heat flux in the mold during the solidification and, thus, 2. z-esults in a significantly higher shrinkage during the casting process, as well as 3. causes a correspondingly higher thermal load of the mold which leads to the danger of longitudinal cracks in the strip surface and leads to lower service lives of the mold.
At the present time, the problems described above lead to uncontrollable surface defects when casting thin strands having a thickness of less than 30mm in plants with a travelling mold, for example, in accordance with the two-roller method (Bessemer principle), the Hazelett method or in belt units and the one-roller method.
The best results have so far been achieved using twin rollers. In this method, liquid steel is cast symmetrically between twa rollers which rotate in opposite directions, the steel solidifies in the narrowest gap between the rollers, i.e., the kissing point, and is discharged through a delivery unit.

The surface quality which is achieved by this method and particularly the accuracy to dimension in thickness direction and width direction, i.e., planarity and sectional size, are not reproducible and cannot be realized with the percentage tolerances for cold strip demanded by the market. This is particularly true for the production of C-steel.
The explanation for this is the solidification behavior of the steel. Under the casting conditions present in the twin rollers, the steel solidifies on a "cold" roller surface in a very short time. The heat flux of about 5MW/m2 flows radially into the roller surface and is decreased by the roller cooling means.
The fallowing effects occur in this connection:
- The roller-type mold which is subjected to a high thermal load has, for example, a cylindrical cold dimension and expands in the contact area due to the thermal increase with the solidifying strand and imparts a negative crown on the strip.
However, a correction of the sectional dimensions during further processing in the rolling mill is practically no longer possible because of the lacking transverse flux in the roller gap in the case of the width/thickness ratios of greater than or equal to 100/1.
- The strand surface shrinks during the solidification parallel to the roller surface in the casting direction as well as in the width direction, so that a tensional stress exists in the strand shell and a compressive stress exists in the mold surface. Simultaneously, the mold surface expands during a rotation cycle due to the heat flux in radial direction as well as in axial direction and produces a tensile stress in the strand surface in both directions.
The superposition of these stresses with the stresses caused by the shrinkage of the strand shell leads to a shrinkage and adherence of the strand shell to the mold surface. This, in turn, leads to the formation of longitudinal cracks due to the axially acting stresses, i.e., transversely of the casting direction, and to transverse cracks due to the radially acting stresses, i.e., longitudinally of the casting direction. With increasing width of the cast sizes, the absolute value and, thus, the influence of the axial shrinkage on the danger of the longitudinal crack formation and on the adjustment of a percentage acceptable planarity and freedom from cracks also increase.

Various patent documents, for example, DE 34 40 234, DE 34 40 235, DE 34 40 237, report about travelling molds in the form of strips and/or rollers. In these instances, it is attempted to improve the surface quality by minimizing the friction between the solidifying surface of the molten metal and the mold material, in order to avoid cracks and achieve a uniform surface quality. A connection or welding between the cold surfaces and the crystallized material are intentionally avoided.
In accordance with another proposal disclosed in DE 34 06 730, a metal foil is continuously supplied into the mold of a horizontal continuous casting plant for the purpose of lubricating the mold wall.
Not salved in the prior art until today are the problems of the high heat flux and the profile and planarity tolerances in the casting of strips, preferably of steel, having widths of between 400mm and 1600mm and thicknesses of less than lOmm.

SU~iARY OF THE INVENTION
Therefore, it is the primary object of the present invention to propose a continuous casting method and a plant for carrying out the method on the basis of an oscillating or travelling mold in which the heat flux from the solidifying melt is controlled in such a way that the shrinkage constitutes a subcritical value, a welding connection between the solidifying melt and the flat product, for example, a hot strip, takes place simultaneously, and an optimum strip geometry with respect to sectional size and planarity is ensured.
In accordance with the present invention, the solidus temperature of the metal sheathing is always smaller than or equal to the solidus temperature of the molten metal.
In the mold of the plant according to the present invention, the sheathing material is guided along at least one of the wall surfaces of the mold.
The unexpected solution according to the present invention resides in the fact that the critical shrinkage of the solidifying strand surface which is subjected to a tensile stress is compensated by the superposition of an oppositely acting compressive stress caused by the expansion of the sheathing which is located between the mold and the liquid metal.
The sheathing itself initially absorbs the heat flux capacitively and, consequently, remains relatively cold at the side facing the mold wall and is capable of absorbing greater stress on this side without the formation of cracks.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
Fig. 1 is a diagram showing the heat fluxes occurring in dependence on casting thickness and casting speed;
Fig. 2 is a schematic illustration of a two-roller casting machine according to the present invention;
Fig. 3 is a diagram explaining the basic requirements for a composite material connection between the solidifying melt and the sheathing; and Fig. 4 is a perspective view, on a larger scale, showing the casting procedure.
il DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 of the drawing is discussed above.
Fig. 2 of the drawing shows a two-roller casting machine according to the present invention.
Liquid steel is introduced from a distributor 1 through a steel supply system 2 into the sheathing 4 which is continuously supplied at least on one side between the melt 3 and a travelling mold 5 and is discharged with the solidifying melt. In the solidifying zone, which simultaneously constitutes the welding zone 6, the solidifying melt 7 or strand shell is welded to the sheathing 4. The complete solidification of the metal strip 13 is concluded at the kissing point, the roller apex 8 or in the area of the strand guide means 10. The strand guide means may be composed of rollers or plates and can be used for reducing the strand thickness. This facilitates an increase of the casting speed, and thus, of the capacity by moving the final solidification 9 out of the roller apex 8 or kissing point.
A cooling system 14 is arranged immediately following the travelling mold 5. The area of the strand guiding means is provided with a housing 15 and may be operated in a gas-controlled and/or temperature-controlled manner.
The method according to the present invention takes place as shown in connection with the example of the twin-roller unit as follows The energy released during the solidification of the steel melt 3 heats the sheathing 4 located between the travelling mold and the steel melt 3 or the strand shell 7 up to 7So1 sheathing on the melt side, which leads to welding of the strand shell to the sheathing 4 in the active area of the mold, i.e., the welding zone 6. In addition, substances 18 for reducing the melting point and for reinforcing the welding process can be applied to the side of the sheathing facing the liquid melt. Due to the composite material connection of sheathing and solidified melt 7, i.e., the strand shell, the tensile stress 12 existing in the strand shell 7 is superimposed and compensated by the compressive stress 11 existing in the sheathing 4.
This makes it possible to control the planarity and profile of the strip to be produced and to avoid longitudinal cracks.
The thermal load acting, for example, on roller-type molds, is substantially reduced by the capacitive heating of the sheathing, so that the service life of the mold is increased at the same time.
By using sheathings of, for example, high-grade steel, aluminum, copper or other non-iron metals, the invention makes it possible to produce composite materials, particularly coated materials, such as stainless coated carbon steel as well as flat or also long products.
Fig. 3 of the drawing shows the basic requirements for a composite material connection between solidifying melt and sheathing.
The solidus temperature of the material serving as sheathing must always be smaller than or equal to the solidus temperature of the melt being used, i . e, TS S",, > = TS
When the melt solidifies at the sheathing, energy is still discharged even when the strand shell cools from Ts s~h to TS ~, which is helpful to the welding action.
For example, a construction steel melt is used with a solidus temperature of, for example, 1,520~C which is cast into a sheathing of high-grade steel having a solidus temperature of, for example, 1,460~C. The released solidification heat of the construction steel heats the sheathing up to 1,460~C and the steel is welded to the sheathing. Because of the solidus temperature difference of 60~C., the high-grade steel layer is partially melted and forms the welding zone during the subsequent common cooling.
The present invention can be used in Hazelett plants as well as casting wheels, as shown in Fig. 4.
The present invention, examples of which have been described above, provides the following advantages:
- Controlled production of a 100 composite material connection by a certain welding between the melt and the sheathing of high-grade steel, non-iron metal or other steel qualities;
- Defined surface in size and planarity;
- Casting of qualities which are sensitive to heat cracks with high casting speeds;

- Substantial cost reduction by substituting, for example, solid stainless steel products by a composite material having at least one stainless surface;
- Freely selectable final and coating thicknesses;
- New material combinations;
- Connection of the casting process with the rolling process is possible in-line;
- No scaling because of specified cooling;
- Low thermal load of the mold due to capacitive heating of the sheathing;
- Possibility of increasing the casting speed (capacity) by moving the final solidification from the roller apex or kissing point; and - Increase of the mold service life.
While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims (14)

1. A method of continuously casting metal with an oscillating or travelling mold for manufacturing sheathed material, the method comprising casting a metal melt between a metal sheathing which continuously travels with casting speed, wherein the solidus temperature of the metal sheathing is always smaller than or equal to the solidus temperature of the metal melt.
2. The method according to claim 1, wherein the metal melt is liquid steel.
3. The method according to claim 1, wherein the metal and the sheathing are of steel.
4. The method according to claim 1, wherein the sheathing is of stainless steel.
5. The method according to claim 1, wherein the sheathing is of a non-iron metal.
6. The method according to claim 1, wherein the sheathing is less than 50% of total thickness.
7. The method according to claim 1, wherein the sheathing material is heated prior to use up to at most the solidus temperature.
8. A plant for manufacturing sheathed material by continuously casting a metal melt in an oscillating or travelling mold, comprising means for casting the metal melt between a metal sheathing travelling continuously with casting speed, the mold having a wall surface, wherein the sheathing material is guided along at least one of the wall surfaces of the mold.
9. The plant according to claim 8, comprising means for controlling the temperature of the mold.
10. The plant according to claim 8, wherein the mold comprises a two-roller mold.
11. The plant according to claim 8, wherein the mold is of a metal or ceramic material.
12. The plant according to claim 8, comprising a strand guiding means for reducing the cross-section of a sheathed metal strip with liquid core.
13. The plant according to claim 8, comprising means for applying substances for reducing the melting point onto a surface of the sheathing facing the melt for reinforcing a composite material connection between the sheathing and the solidifying melt.
14. The plant according to claim 8, further comprising a gas-controlled housing, wherein the sheathed metal strip is guided through the housing.
CA002229750A 1996-12-11 1998-02-18 Method and plant for producing sheathed continuously cast products Abandoned CA2229750A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
DE19651324A DE19651324C2 (en) 1996-12-11 1996-12-11 Method and device for producing coated continuous cast products
EP97119937A EP0852165A3 (en) 1996-12-11 1997-11-14 Method and apparatus for producing of coated continuous casting products
JP10022361A JPH11221651A (en) 1996-12-11 1998-02-03 Method for making forged product subjected to coating and apparatus therefor
BR9806394-4A BR9806394A (en) 1996-12-11 1998-02-17 Process and device for the production of products involved in continuous casting.
CA002229750A CA2229750A1 (en) 1996-12-11 1998-02-18 Method and plant for producing sheathed continuously cast products
AU55378/98A AU5537898A (en) 1996-12-11 1998-02-19 Method and plant for producing sheathed continuously cast products
ZA981366A ZA981366B (en) 1996-12-11 1998-02-19 Sheathed continuously cast products

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
DE19651324A DE19651324C2 (en) 1996-12-11 1996-12-11 Method and device for producing coated continuous cast products
JP10022361A JPH11221651A (en) 1996-12-11 1998-02-03 Method for making forged product subjected to coating and apparatus therefor
BR9806394-4A BR9806394A (en) 1996-12-11 1998-02-17 Process and device for the production of products involved in continuous casting.
CA002229750A CA2229750A1 (en) 1996-12-11 1998-02-18 Method and plant for producing sheathed continuously cast products
AU55378/98A AU5537898A (en) 1996-12-11 1998-02-19 Method and plant for producing sheathed continuously cast products
ZA981366A ZA981366B (en) 1996-12-11 1998-02-19 Sheathed continuously cast products

Publications (1)

Publication Number Publication Date
CA2229750A1 true CA2229750A1 (en) 1999-08-18

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ID=31950875

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002229750A Abandoned CA2229750A1 (en) 1996-12-11 1998-02-18 Method and plant for producing sheathed continuously cast products

Country Status (7)

Country Link
EP (1) EP0852165A3 (en)
JP (1) JPH11221651A (en)
AU (1) AU5537898A (en)
BR (1) BR9806394A (en)
CA (1) CA2229750A1 (en)
DE (1) DE19651324C2 (en)
ZA (1) ZA981366B (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19850213C2 (en) * 1998-01-23 2001-08-30 Sms Demag Ag Casting process for a thin metal strip and associated casting device
DE10333589B9 (en) * 2003-07-24 2010-06-10 Federal-Mogul Wiesbaden Gmbh & Co. Kg Method for producing a band-shaped composite material for slide bearing production and apparatus for carrying out the method
DE102006057858A1 (en) 2006-12-08 2008-08-21 Vladimir Volchkov 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
DE102012017684A1 (en) 2012-08-31 2014-03-06 Vladimir Volchkov Continuous casting of non-ferrous metals, comprises casting a melt of non-ferrous metal on movable metallic sheath, which is made of band, subjecting band edges to continuous welding to form melt, and wrapping continuous cast block
DE102012017682A1 (en) 2012-08-31 2014-03-06 Vladimir Volchkov Continuous casting of non-ferrous metals involves pouring melt of non-ferrous metal in continuously formed movable metallic sheath, forming continuous cast block, and continuously welding edge strips in controlled protective atmosphere
US11027330B2 (en) 2016-08-10 2021-06-08 Nucor Corporation Method of thin strip casting

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2055980A (en) * 1933-04-12 1936-09-29 Alfred J Liebmann Method of casting or molding metals
US2128943A (en) * 1936-04-01 1938-09-06 American Rolling Mill Co Formation of encased structures by direct casting
FR1435936A (en) * 1965-03-08 1966-04-22 Siderurgie Fse Inst Rech Method and device for the continuous casting of liquid products
DE3340844C1 (en) * 1983-11-11 1984-12-20 Mannesmann AG, 4000 Düsseldorf Continuous casting mold with cooling device for casting metal, especially steel
JPH0360848A (en) * 1989-07-31 1991-03-15 Nippon Steel Corp Production of 18-8 series austenite stainless steel strip
US5476725A (en) * 1991-03-18 1995-12-19 Aluminum Company Of America Clad metallurgical products and methods of manufacture

Also Published As

Publication number Publication date
ZA981366B (en) 1998-09-30
JPH11221651A (en) 1999-08-17
BR9806394A (en) 1999-12-21
AU5537898A (en) 1999-09-02
EP0852165A3 (en) 1999-01-07
DE19651324A1 (en) 1998-06-18
EP0852165A2 (en) 1998-07-08
DE19651324C2 (en) 1999-03-18

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