CA2560681A1 - Method and installation for producing light gauge steel with a high manganese content - Google Patents
Method and installation for producing light gauge steel with a high manganese content Download PDFInfo
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- CA2560681A1 CA2560681A1 CA002560681A CA2560681A CA2560681A1 CA 2560681 A1 CA2560681 A1 CA 2560681A1 CA 002560681 A CA002560681 A CA 002560681A CA 2560681 A CA2560681 A CA 2560681A CA 2560681 A1 CA2560681 A1 CA 2560681A1
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 37
- 239000010959 steel Substances 0.000 title claims abstract description 37
- 239000011572 manganese Substances 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 21
- 229910052748 manganese Inorganic materials 0.000 title claims abstract description 14
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 title claims abstract description 9
- 238000009434 installation Methods 0.000 title claims description 20
- 239000000843 powder Substances 0.000 claims abstract description 24
- 238000005266 casting Methods 0.000 claims abstract description 17
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 10
- 238000007711 solidification Methods 0.000 claims abstract description 10
- 230000008023 solidification Effects 0.000 claims abstract description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000009749 continuous casting Methods 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims abstract description 6
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 6
- 239000000126 substance Substances 0.000 claims abstract description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000010703 silicon Substances 0.000 claims abstract description 4
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 3
- 230000004907 flux Effects 0.000 claims description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 230000009467 reduction Effects 0.000 claims description 7
- 229910052681 coesite Inorganic materials 0.000 claims description 6
- 229910052906 cristobalite Inorganic materials 0.000 claims description 6
- 229910052682 stishovite Inorganic materials 0.000 claims description 6
- 229910052905 tridymite Inorganic materials 0.000 claims description 6
- 238000005098 hot rolling Methods 0.000 claims description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 2
- 238000005520 cutting process Methods 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims 3
- 235000012239 silicon dioxide Nutrition 0.000 claims 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims 2
- 229910052593 corundum Inorganic materials 0.000 claims 2
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims 2
- 229910001845 yogo sapphire Inorganic materials 0.000 claims 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims 1
- 229910052500 inorganic mineral Inorganic materials 0.000 claims 1
- 239000011707 mineral Substances 0.000 claims 1
- 238000005275 alloying Methods 0.000 abstract description 6
- 230000003647 oxidation Effects 0.000 abstract description 4
- 238000007254 oxidation reaction Methods 0.000 abstract description 4
- 238000003303 reheating Methods 0.000 abstract description 2
- 239000004411 aluminium Substances 0.000 abstract 4
- 238000005204 segregation Methods 0.000 abstract 2
- 229910000746 Structural steel Inorganic materials 0.000 abstract 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 4
- 238000005336 cracking Methods 0.000 description 3
- 238000005461 lubrication Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 101100348017 Drosophila melanogaster Nazo gene Proteins 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910000914 Mn alloy Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000011165 process development Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- 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
- B21B1/466—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 in a non-continuous process, i.e. the cast being cut before rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
- B22D11/111—Treating the molten metal by using protecting powders
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/1213—Accessories for subsequent treating or working cast stock in situ for heating or insulating strands
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/14—Plants for continuous casting
- B22D11/142—Plants for continuous casting for curved casting
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
-
- 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
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
- C21D8/0215—Rapid solidification; Thin strip casting
Abstract
For various reasons, in the prior art it is considered difficult or impossible to produce steels with high manganese (Mn), aluminium (AI) and silicon (Si) contents and with TWIP (Twinning Induced Plasticity) properties by continuous casting. The reasons cited include low strength of the strand shell during solidification on account of extensive micro-segregation of Mn, high strength at lower temperatures, reactions of the aluminium in the steel with the casting powder, macro-segregations, depletion of the alloying elements in the surface region and oxidation of the grain boundaries during the reheating of slabs in the pusher furnace. Therefore, the invention proposes that, by successive process steps, lightweight structural steel with a predetermined chemical composition of up to 27% Mn, 1 to 6% AI, 1 to 6% Si, < 0.8% C, remainder Fe and accompanying elements, be cast on a thin-slab casting machine (1 ) (d <= 120 mm) using suitable casting powders, then immediately after the solidification slabs (3) be severed from the endless strand (2) and that temperature equalization be carried out during continuous passage through an intermediate furnace (4) and then the slab (3) be directly hot-rolled without intervening cooling.
Description
METHOD AND INSTALLATION FOR PRODUCING LIGHT GAUGE
STEEL WITH A HIGH MANGANESE CONTENT
The invention concerns a method and an installation for producing hot-rolled strip from a highly cold-workable, high-strength, austenitic light gauge steel with increased contents of manganese (Mn), aluminum (A1), and silicon (Si) with TWIP
properties (Twinning-Induced Plasticity), wherein the steel is first cast into an endless strand in a continuous casting installation, cut into slabs, and then rolled to the final thickness.
Austenitic light gauge steels with TWIP properties for use, e.g., in automobile body parts, reinforcing automobile body members, and cryogenic tanks and pipelines have, for example, according to EP 0 889 144 B1, a chemical composition of 10-300 Mn, 1-6o Si, 1-8o A1 (with Si + Al <_ 120), with the remainder consisting of Fe.
DE 199 00 199 A1 discloses a high-strength light gauge steel with 7-30o Mn, 1-loo Al, 0.7-4o Si, _< lOs Cr, <_ loo Ni, <_ 3o Cu, -<< 0.5o C, and optionally with the additional alloying elements N, Va, Nb, Ti, and P, which has not only good mechanical properties but also good resistance to corrosion and stress-corrosion cracking. This steel is intended to be cast by continuous casting and hot rolled or to be cast by thin-strip casting with near-net shape.
The production of high-manganese steels by continuous casting is considered difficult or impossible in the present state of the art for various reasons, namely, low strength of the strand shell during solidification due to intense microsegregation of Mn (danger of breakout at Mn > 150), high strength at relatively low temperatures (installation overloading, cracking problems), reactions of the aluminum in the steel with the flux powder (limitation of function), macrosegregation, hydrogen and/or oxygen absorption by spray water cooling, increased occurrence of nonmetallic inclusions, depletion of the alloying elements near the surface, and oxidation of the grain boundaries during the reheating of slabs in the pusher furnace.
In a publication by Spitzer et al.: "Innovative Steel Products -- Challenge for Process Development"; Conference Report: Barbara 2001, pp. 71-84, it is stated in this regard that steels with increasing manganese contents are increasingly difficult to cast. For one thing, they have low strength at high temperatures after solidification, since at high manganese contents, manganese becomes highly concentrated in the residual melt and lowers the melting point in the interdendritic regions.
This increases the tendency towards sticking-type breakouts, which make continuous casting impossible at Mn contents of 150 or more according to present estimates. On the other hand, the steels have high strength at low temperatures, so that installation overloading occurs during the bending of the steel, and cracking must be expected. In addition, at aluminum contents of several percent, which are used in these steels for the purpose, among others, of reducing the density, reactions occur with the flux powder, which have serious adverse effects on the function of the flux powder.
In another publication by Gigacher et al.: "Properties of High-Manganese Steels under Conditions Similar to Continuous Casting"; BHM 149 (2004), No. 3, pp. 112-117, it is stated in summary that the casting of the alloying concepts presented there for the production of TWIP steels is not advantageous for methods with flux powders.
The principal problem with the casting of steels with a high A1 content (> lo) is the reaction of the Al from the steel with the oxide constituents of the flux powder. The reduction of the Si02 in the slag by the A1 from the steel gives rise to A1~03, which is absorbed by the slag and causes the basicity of the slag (the Ca0/Si02 ratio) to increase. This leads to very sharp changes in viscosity and in the lubrication conditions in the mold.
Due to these difficulties, various approaches for the production of TWIP steels have been taken:
WO 02/101109 A1 discloses a method in which a significant reduction of the offset yield stress and thus an improvement of the formability by hot rolling and cold rolling are achieved by increasing the possible carbon content (C _< lo) and by adding additional elements, here especially B as well as Ni, Cu, N, Nb, Ti, V, and P. To produce this steel, a feedstock (slab, thin slab, or strip) is heated and hot rolled and coiled within specific temperature limits.
EP 1 341 937 B1 describes a method in which a steel containing 12-30o Mn is cast in a twin-roll casting machine into a near-net shape thin strip with a thickness of less than 1 mm to 6 mm. The near-net shape strip emerging vertically from the casting gap is cooled by coolants applied to its surface and is then rolled to the final thickness in a single hot rolling pass.
The total time interval between the exit from the casting gap and the entry into the rolling stand is about 8 seconds.
EP 1 067 203 Bl discloses a method for producing strip made of an Fe-C-Mn alloy in which a thin steel strip with a thickness of 1.5-10 mm and a composition of 6-30s Mn, 0.001 to 1.6o C, 2.5 Si, ~ 6o Al, <_ 10o Cr and other elements is first cast on a twin-roll casting machine and then hot rolled in one or more stages with 10-60o reduction.
Based on this prior art, the objective of the invention is to specify a method and an installation which can be realized as simply as possible and with which high-manganese steels with a given chemical composition can be produced by continuous casting.
The objective with respect to the method is achieved by the characterizing features of Claim 1, which involve the use of successive process steps, in which a light gauge steel with the given chemical composition of 15-27o Mn, 1-6o A1, 1-60 5i, 0.8o C with the remainder consisting of Fe and accompanying impurity elements ~ is cast on a thin-slab casting machine (d < 120 mm) with the use of suitable flux powders, which very quickly reach equilibrium and then undergo no further change in their lubrication behavior, and is then cut into slabs, ~ immediately after the solidification and cutting of a slab, temperature equalization is brought about in a continuous-type intermediate furnace, and then ~ the slab is immediately hot rolled without intermediate cooling.
An installation for carrying out the method is characterized by the features of Claim 7.
In the production of thin slabs, for example, on CSP
casting machines (CSP = Compact Strip Production), the strand is withdrawn vertically, bent horizontally after solidification, and then cut into slabs. Therefore, no problems can arise with internal cracks. The production of high-strength austenitic steels without installation overloading is possible and in the meantime has become the state of the art.
Microsegregations that are still present in the strand after solidification are largely removed again by diffusion during passage through the intermediate furnace, for example, through a roller hearth furnace, before the subsequent rolling deformation. In the process, the macrosegregations in the slab center are sufficiently equalized during the intense deformation in the hot rolling mill, much like high-grade austenitic steels.
In accordance with the invention, the use of the roller hearth furnace of a CSP installation advantageously avoids any relatively great depletion of the alloying elements. and oxidation of the grain boundaries due to the short passage time.
Depletion of the alloying elements and oxidation of the grain boundaries can cause problems, for example, during the relatively long heating times in the pusher furnace of a conventional hot-rolled wide strip mill in accordance with the prior art.
In accordance with the invention, to be able to use the technology of casting TWIP light gauge steels with high Mn and A1 contents on a thin-slab casting machine, it is necessary to use a suitable flux powder. In accordance with the invention, a suitable flux powder is one which has the property of achieving equilibrium very quickly and then undergoing no further change in its lubrication behavior.
In order, for example, to reduce the reaction rate of the SiOj reduction by the A1 in the steel, the flux powder used in accordance with the invention has a high content of A120~ of >
100. Alternatively or additionally, to have more SiO~ available in the equilibrium state, the SiOz content of the flux powder is increased sufficiently to obtain a basicity (Ca0/SiOz ratio) of 0.5-0.7.
Since MnOz is more readily reduced than SiOz by the A1 in the steel, and thus the SiOz is protected from this reduction (protected from loss), an additional measure that can be taken in accordance with the invention is the addition of MnO~ to the flux powder.
In accordance with the invention, it is also possible to add TiOz to the flux powder as a partial replacement of the Si02, since Ti02 also has a vitrifying effect but is not attacked (reduced) by the A1 in the steel.
Finally, it is also possible to lower the viscosity of the flux powder in the mold. This increases the consumption of flux powder, and more of the AlzO~ that is formed is removed, so that an equilibrium with lower A1z03 concentrations is established.
This reduction in viscosity is achieved by the addition of B~03 (borate) , NazO, and/or LiOl~ to the flux powder.
The process diagram of an installation of the invention for producing hot-rolled strip is shown in the schematic drawing and is explained in detail below.
The installation is basically a well-known CSP
installation, in which, in accordance with the invention, the distances between the individual installation units were changed in such a way that the method of the invention can be carried out with the requirements that temperature equalization is brought about in a continuous-type intermediate furnace immediately after the solidification and that the slab is then immediately hot rolled without intermediate cooling.
Accordingly, the installation illustrated in the drawing consists of a thin-slab casting machine 1 and a downstream intermediate furnace 4, into which the slab 3 is fed after it has solidified and has been cut from the endless strand 2. The intermediate furnace 4 is followed by a rolling mill 5, in which the slab 3, after it has been subjected to temperature equalization in the intermediate furnace 4, is immediately (i.e., without intermediate cooling) rolled out into hot-rolled strip 6.
STEEL WITH A HIGH MANGANESE CONTENT
The invention concerns a method and an installation for producing hot-rolled strip from a highly cold-workable, high-strength, austenitic light gauge steel with increased contents of manganese (Mn), aluminum (A1), and silicon (Si) with TWIP
properties (Twinning-Induced Plasticity), wherein the steel is first cast into an endless strand in a continuous casting installation, cut into slabs, and then rolled to the final thickness.
Austenitic light gauge steels with TWIP properties for use, e.g., in automobile body parts, reinforcing automobile body members, and cryogenic tanks and pipelines have, for example, according to EP 0 889 144 B1, a chemical composition of 10-300 Mn, 1-6o Si, 1-8o A1 (with Si + Al <_ 120), with the remainder consisting of Fe.
DE 199 00 199 A1 discloses a high-strength light gauge steel with 7-30o Mn, 1-loo Al, 0.7-4o Si, _< lOs Cr, <_ loo Ni, <_ 3o Cu, -<< 0.5o C, and optionally with the additional alloying elements N, Va, Nb, Ti, and P, which has not only good mechanical properties but also good resistance to corrosion and stress-corrosion cracking. This steel is intended to be cast by continuous casting and hot rolled or to be cast by thin-strip casting with near-net shape.
The production of high-manganese steels by continuous casting is considered difficult or impossible in the present state of the art for various reasons, namely, low strength of the strand shell during solidification due to intense microsegregation of Mn (danger of breakout at Mn > 150), high strength at relatively low temperatures (installation overloading, cracking problems), reactions of the aluminum in the steel with the flux powder (limitation of function), macrosegregation, hydrogen and/or oxygen absorption by spray water cooling, increased occurrence of nonmetallic inclusions, depletion of the alloying elements near the surface, and oxidation of the grain boundaries during the reheating of slabs in the pusher furnace.
In a publication by Spitzer et al.: "Innovative Steel Products -- Challenge for Process Development"; Conference Report: Barbara 2001, pp. 71-84, it is stated in this regard that steels with increasing manganese contents are increasingly difficult to cast. For one thing, they have low strength at high temperatures after solidification, since at high manganese contents, manganese becomes highly concentrated in the residual melt and lowers the melting point in the interdendritic regions.
This increases the tendency towards sticking-type breakouts, which make continuous casting impossible at Mn contents of 150 or more according to present estimates. On the other hand, the steels have high strength at low temperatures, so that installation overloading occurs during the bending of the steel, and cracking must be expected. In addition, at aluminum contents of several percent, which are used in these steels for the purpose, among others, of reducing the density, reactions occur with the flux powder, which have serious adverse effects on the function of the flux powder.
In another publication by Gigacher et al.: "Properties of High-Manganese Steels under Conditions Similar to Continuous Casting"; BHM 149 (2004), No. 3, pp. 112-117, it is stated in summary that the casting of the alloying concepts presented there for the production of TWIP steels is not advantageous for methods with flux powders.
The principal problem with the casting of steels with a high A1 content (> lo) is the reaction of the Al from the steel with the oxide constituents of the flux powder. The reduction of the Si02 in the slag by the A1 from the steel gives rise to A1~03, which is absorbed by the slag and causes the basicity of the slag (the Ca0/Si02 ratio) to increase. This leads to very sharp changes in viscosity and in the lubrication conditions in the mold.
Due to these difficulties, various approaches for the production of TWIP steels have been taken:
WO 02/101109 A1 discloses a method in which a significant reduction of the offset yield stress and thus an improvement of the formability by hot rolling and cold rolling are achieved by increasing the possible carbon content (C _< lo) and by adding additional elements, here especially B as well as Ni, Cu, N, Nb, Ti, V, and P. To produce this steel, a feedstock (slab, thin slab, or strip) is heated and hot rolled and coiled within specific temperature limits.
EP 1 341 937 B1 describes a method in which a steel containing 12-30o Mn is cast in a twin-roll casting machine into a near-net shape thin strip with a thickness of less than 1 mm to 6 mm. The near-net shape strip emerging vertically from the casting gap is cooled by coolants applied to its surface and is then rolled to the final thickness in a single hot rolling pass.
The total time interval between the exit from the casting gap and the entry into the rolling stand is about 8 seconds.
EP 1 067 203 Bl discloses a method for producing strip made of an Fe-C-Mn alloy in which a thin steel strip with a thickness of 1.5-10 mm and a composition of 6-30s Mn, 0.001 to 1.6o C, 2.5 Si, ~ 6o Al, <_ 10o Cr and other elements is first cast on a twin-roll casting machine and then hot rolled in one or more stages with 10-60o reduction.
Based on this prior art, the objective of the invention is to specify a method and an installation which can be realized as simply as possible and with which high-manganese steels with a given chemical composition can be produced by continuous casting.
The objective with respect to the method is achieved by the characterizing features of Claim 1, which involve the use of successive process steps, in which a light gauge steel with the given chemical composition of 15-27o Mn, 1-6o A1, 1-60 5i, 0.8o C with the remainder consisting of Fe and accompanying impurity elements ~ is cast on a thin-slab casting machine (d < 120 mm) with the use of suitable flux powders, which very quickly reach equilibrium and then undergo no further change in their lubrication behavior, and is then cut into slabs, ~ immediately after the solidification and cutting of a slab, temperature equalization is brought about in a continuous-type intermediate furnace, and then ~ the slab is immediately hot rolled without intermediate cooling.
An installation for carrying out the method is characterized by the features of Claim 7.
In the production of thin slabs, for example, on CSP
casting machines (CSP = Compact Strip Production), the strand is withdrawn vertically, bent horizontally after solidification, and then cut into slabs. Therefore, no problems can arise with internal cracks. The production of high-strength austenitic steels without installation overloading is possible and in the meantime has become the state of the art.
Microsegregations that are still present in the strand after solidification are largely removed again by diffusion during passage through the intermediate furnace, for example, through a roller hearth furnace, before the subsequent rolling deformation. In the process, the macrosegregations in the slab center are sufficiently equalized during the intense deformation in the hot rolling mill, much like high-grade austenitic steels.
In accordance with the invention, the use of the roller hearth furnace of a CSP installation advantageously avoids any relatively great depletion of the alloying elements. and oxidation of the grain boundaries due to the short passage time.
Depletion of the alloying elements and oxidation of the grain boundaries can cause problems, for example, during the relatively long heating times in the pusher furnace of a conventional hot-rolled wide strip mill in accordance with the prior art.
In accordance with the invention, to be able to use the technology of casting TWIP light gauge steels with high Mn and A1 contents on a thin-slab casting machine, it is necessary to use a suitable flux powder. In accordance with the invention, a suitable flux powder is one which has the property of achieving equilibrium very quickly and then undergoing no further change in its lubrication behavior.
In order, for example, to reduce the reaction rate of the SiOj reduction by the A1 in the steel, the flux powder used in accordance with the invention has a high content of A120~ of >
100. Alternatively or additionally, to have more SiO~ available in the equilibrium state, the SiOz content of the flux powder is increased sufficiently to obtain a basicity (Ca0/SiOz ratio) of 0.5-0.7.
Since MnOz is more readily reduced than SiOz by the A1 in the steel, and thus the SiOz is protected from this reduction (protected from loss), an additional measure that can be taken in accordance with the invention is the addition of MnO~ to the flux powder.
In accordance with the invention, it is also possible to add TiOz to the flux powder as a partial replacement of the Si02, since Ti02 also has a vitrifying effect but is not attacked (reduced) by the A1 in the steel.
Finally, it is also possible to lower the viscosity of the flux powder in the mold. This increases the consumption of flux powder, and more of the AlzO~ that is formed is removed, so that an equilibrium with lower A1z03 concentrations is established.
This reduction in viscosity is achieved by the addition of B~03 (borate) , NazO, and/or LiOl~ to the flux powder.
The process diagram of an installation of the invention for producing hot-rolled strip is shown in the schematic drawing and is explained in detail below.
The installation is basically a well-known CSP
installation, in which, in accordance with the invention, the distances between the individual installation units were changed in such a way that the method of the invention can be carried out with the requirements that temperature equalization is brought about in a continuous-type intermediate furnace immediately after the solidification and that the slab is then immediately hot rolled without intermediate cooling.
Accordingly, the installation illustrated in the drawing consists of a thin-slab casting machine 1 and a downstream intermediate furnace 4, into which the slab 3 is fed after it has solidified and has been cut from the endless strand 2. The intermediate furnace 4 is followed by a rolling mill 5, in which the slab 3, after it has been subjected to temperature equalization in the intermediate furnace 4, is immediately (i.e., without intermediate cooling) rolled out into hot-rolled strip 6.
Claims (7)
1. Method for producing hot-rolled strip (6) from a highly cold-workable, high-strength, austenitic light gauge steel with increased contents of manganese (Mn), aluminum (Al), and silicon (Si) with TWIP properties (Twinning-Induced Plasticity), wherein the light gauge steel is first cast into an endless strand (2) in a continuous casting installation (1), cut into slabs. (3), and then rolled to the final thickness, characterized by the fact that successive process steps are used, in which a light gauge steel with the given chemical composition of 15-27% Mn, 1-6% Al, 1-6% Si, <= 0.8% C, with the remainder consisting of Fe and impurities .cndot. is cast on a thin-slab casting machine (1) (d <= 120 mm) with the use of flux powders and cut into slabs (3), such that suitable mineral substances are added to the flux powders to reduce the reaction rate of the SiO2 reduction by the Al in the steel and/or to reduce the amount of Al2O3 that is formed by lowering the viscosity in the mold, .cndot. immediately after the solidification of the endless strand (2) and cutting of a slab (3), temperature equalization is brought about in a continuous-type intermediate furnace (4), and then .cndot. the slab (3) is immediately hot rolled without intermediate cooling.
2. Method in accordance with Claim 1, characterized by the fact that the flux powder has an increased Al2O3 content of >
10%.
10%.
3. Method in accordance with Claim 1 or Claim 2, characterized by the fact that the flux powder has an increased SiO2 content with a basicity (CaO/SiO2 ratio) of 0.5-0.7.
4. Method in accordance with Claim 1, Claim 2, or Claim 3, characterized by the fact that the flux powder contains MnO2 and/or TiO2.
5. Method in accordance with Claim 1, Claim 2, Claim 3, or Claim 4, characterized by the fact that, to lower the viscosity of the flux powder in the mold, the flux powder contains B2O3 (borate), Na2O, and/or LiO2.
6. Method in accordance with one or more of Claims 1 to 5, characterized by the fact that the intermediate furnace (4) is a roller hearth furnace.
7. Installation for producing hot-rolled strip from a highly cold-workable, high-strength, austenitic light gauge steel with increased contents of manganese (Mn), aluminum (A1,) and silicon (Si) with TWIP properties (Twinning-Induced Plasticity) for carrying out the method in accordance with one or more of Claims 1 to 6, which consists of a CSP installation (Compact Strip Production) with the successively arranged installation units thin-slab casting machine (1), intermediate furnace (4), and hot rolling mill (5), characterized by the fact that the distances between the individual installation units are changed in such a way that immediately after the solidification of the endless strand (2), temperature equalization of a cut slab (3) is brought about in a continuous-type intermediate furnace (4), and then the slab (3) is immediately hot rolled without intermediate cooling.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102005010243A DE102005010243A1 (en) | 2005-03-05 | 2005-03-05 | Method and plant for producing a lightweight steel with a high manganese content |
| DE102005010243.3 | 2005-03-05 | ||
| PCT/EP2006/001954 WO2006094718A1 (en) | 2005-03-05 | 2006-03-03 | Process and installation for producing a lightweight structural steel with a high manganese content |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2560681A1 true CA2560681A1 (en) | 2006-09-14 |
Family
ID=36218445
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002560681A Abandoned CA2560681A1 (en) | 2005-03-05 | 2006-03-03 | Method and installation for producing light gauge steel with a high manganese content |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US20080164003A1 (en) |
| EP (1) | EP1725347B1 (en) |
| JP (1) | JP4688890B2 (en) |
| KR (1) | KR101153735B1 (en) |
| CN (1) | CN101160183B (en) |
| CA (1) | CA2560681A1 (en) |
| DE (1) | DE102005010243A1 (en) |
| RU (1) | RU2335358C2 (en) |
| TW (1) | TW200700566A (en) |
| UA (1) | UA80237C2 (en) |
| WO (1) | WO2006094718A1 (en) |
| ZA (1) | ZA200607920B (en) |
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| DE102008005806A1 (en) * | 2008-01-17 | 2009-09-10 | Technische Universität Bergakademie Freiberg | Components made of high-manganese, solid and tough cast steel, processes for their production and their use |
| EP2257394B1 (en) * | 2008-01-30 | 2018-11-07 | Tata Steel IJmuiden BV | Method of producing a hot-rolled twip-steel and a twip-steel product produced thereby |
| CN101543837B (en) * | 2008-03-24 | 2012-02-29 | 宝山钢铁股份有限公司 | Method for manufacturing Fe-Mn-C series high-manganese steel thin strip by continuous casting and tandem rolling |
| DE102009030324A1 (en) * | 2009-06-24 | 2011-01-05 | Voestalpine Stahl Gmbh | Manganese steel and process for producing the same |
| DE102010034161B4 (en) * | 2010-03-16 | 2014-01-02 | Salzgitter Flachstahl Gmbh | Method for producing workpieces made of lightweight steel with material properties that can be adjusted via the wall thickness |
| CN104328360B (en) * | 2014-11-20 | 2017-02-22 | 北京科技大学 | Double-phase twinborn induced plastic super-strength automobile steel plate and preparation method thereof |
| CN104711494B (en) * | 2015-04-14 | 2017-11-28 | 钢铁研究总院 | Low-density high-ductility NiAl strengthens unimach and preparation method |
| CN106480366A (en) * | 2015-08-31 | 2017-03-08 | 鞍钢股份有限公司 | A kind of high equiaxial crystal ratio potassium steel steel ingot and its smelting process |
| CN106653127B (en) * | 2015-10-28 | 2018-03-23 | 丹阳市龙鑫合金有限公司 | A kind of ACP1000 used in nuclear power station antivibration bar assembly and its production method |
| CN106624601A (en) * | 2015-10-28 | 2017-05-10 | 丹阳市龙鑫合金有限公司 | Anti-vibration strip assembly for nuclear power station and production method thereof |
| CN106624602A (en) * | 2015-10-28 | 2017-05-10 | 丹阳市龙鑫合金有限公司 | Vibration-resistant bar component for water reactor nuclear power plant ACP1000 and production method of component |
| CN106653128B (en) * | 2015-10-28 | 2018-03-23 | 丹阳市龙鑫合金有限公司 | ACP1000 used in nuclear power station antivibration bar assemblies and its production method |
| CN106624603A (en) * | 2015-10-28 | 2017-05-10 | 丹阳市龙鑫合金有限公司 | ACP1000 anti-vibration strip assembly and production method thereof |
| CN106271449A (en) * | 2016-08-31 | 2017-01-04 | 云南德胜钢铁有限公司 | A kind of technique using bloom production fine grain valve snail reinforcing bar |
| CN110238203A (en) * | 2019-06-13 | 2019-09-17 | 首钢集团有限公司 | A method of it eliminating hot rolling tool steel edge and sticks up skin |
| CN110819908B (en) * | 2019-11-18 | 2021-03-23 | 燕山大学 | High-strength low-density austenitic steel and preparation method thereof |
| CN112391571A (en) * | 2020-11-25 | 2021-02-23 | 攀钢集团西昌钢钒有限公司 | Control method for cleanliness of high-strength high-aluminum high-manganese steel |
| CN112760568B (en) * | 2020-12-25 | 2022-02-25 | 钢铁研究总院 | High-strength high-plasticity low-density steel and preparation method thereof |
| CN115058661A (en) * | 2022-06-17 | 2022-09-16 | 湖南华菱涟源钢铁有限公司 | High-carbon high-manganese steel plate and production method thereof |
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| DE10047044A1 (en) * | 2000-09-22 | 2002-04-25 | Sms Demag Ag | Processes and plants for the production of steel strips and sheets |
| JP3418739B2 (en) * | 2000-09-29 | 2003-06-23 | 川崎重工業株式会社 | Continuous casting hot rolling equipment and continuous casting hot rolling method |
| DE10060948C2 (en) * | 2000-12-06 | 2003-07-31 | Thyssenkrupp Stahl Ag | Process for producing a hot strip from a steel with a high manganese content |
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| DE10128544C2 (en) * | 2001-06-13 | 2003-06-05 | Thyssenkrupp Stahl Ag | High-strength, cold-workable sheet steel, process for its production and use of such a sheet |
| JP2003053496A (en) * | 2001-08-07 | 2003-02-26 | Sanyo Special Steel Co Ltd | Mold powder for continuously casting aluminum- containing steel |
-
2005
- 2005-03-05 DE DE102005010243A patent/DE102005010243A1/en not_active Withdrawn
-
2006
- 2006-03-03 KR KR1020067018434A patent/KR101153735B1/en not_active IP Right Cessation
- 2006-03-03 CA CA002560681A patent/CA2560681A1/en not_active Abandoned
- 2006-03-03 US US11/666,535 patent/US20080164003A1/en not_active Abandoned
- 2006-03-03 RU RU2006136036/02A patent/RU2335358C2/en not_active IP Right Cessation
- 2006-03-03 EP EP06723198A patent/EP1725347B1/en active Active
- 2006-03-03 TW TW095107128A patent/TW200700566A/en unknown
- 2006-03-03 CN CN2006800071903A patent/CN101160183B/en not_active Expired - Fee Related
- 2006-03-03 WO PCT/EP2006/001954 patent/WO2006094718A1/en active Application Filing
- 2006-03-03 UA UAA200611050A patent/UA80237C2/en unknown
- 2006-03-03 JP JP2007557433A patent/JP4688890B2/en not_active Expired - Fee Related
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Also Published As
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| RU2335358C2 (en) | 2008-10-10 |
| EP1725347A1 (en) | 2006-11-29 |
| EP1725347B1 (en) | 2012-12-26 |
| US20080164003A1 (en) | 2008-07-10 |
| CN101160183B (en) | 2011-07-06 |
| WO2006094718A1 (en) | 2006-09-14 |
| CN101160183A (en) | 2008-04-09 |
| JP2008531292A (en) | 2008-08-14 |
| KR20070108440A (en) | 2007-11-12 |
| TW200700566A (en) | 2007-01-01 |
| DE102005010243A1 (en) | 2006-09-07 |
| ZA200607920B (en) | 2008-04-30 |
| UA80237C2 (en) | 2007-08-27 |
| KR101153735B1 (en) | 2012-06-08 |
| RU2006136036A (en) | 2008-05-10 |
| JP4688890B2 (en) | 2011-05-25 |
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