CA2599440C - Method for the continuous casting of a metal with improved mechanical strength and product obtained by the method - Google Patents
Method for the continuous casting of a metal with improved mechanical strength and product obtained by the method Download PDFInfo
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- CA2599440C CA2599440C CA2599440A CA2599440A CA2599440C CA 2599440 C CA2599440 C CA 2599440C CA 2599440 A CA2599440 A CA 2599440A CA 2599440 A CA2599440 A CA 2599440A CA 2599440 C CA2599440 C CA 2599440C
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 36
- 239000002184 metal Substances 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000009749 continuous casting Methods 0.000 title claims abstract description 21
- 239000002105 nanoparticle Substances 0.000 claims abstract description 29
- 239000000919 ceramic Substances 0.000 claims abstract description 25
- 239000011343 solid material Substances 0.000 claims abstract description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 42
- 239000010959 steel Substances 0.000 claims description 42
- 239000002245 particle Substances 0.000 claims description 27
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 26
- 239000000203 mixture Substances 0.000 claims description 14
- 229910052742 iron Inorganic materials 0.000 claims description 13
- 239000011159 matrix material Substances 0.000 claims description 13
- 238000002347 injection Methods 0.000 claims description 11
- 239000007924 injection Substances 0.000 claims description 11
- 238000009826 distribution Methods 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 239000011859 microparticle Substances 0.000 claims description 4
- 238000010079 rubber tapping Methods 0.000 claims description 4
- 229910052681 coesite Inorganic materials 0.000 claims description 3
- 229910052906 cristobalite Inorganic materials 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 238000000462 isostatic pressing Methods 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 229910052682 stishovite Inorganic materials 0.000 claims description 3
- 229910052905 tridymite Inorganic materials 0.000 claims description 3
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 claims description 3
- 229910002065 alloy metal Inorganic materials 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 229910052728 basic metal Inorganic materials 0.000 claims description 2
- 150000003818 basic metals Chemical class 0.000 claims description 2
- 230000003068 static effect Effects 0.000 claims description 2
- 239000000725 suspension Substances 0.000 claims description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims 2
- 229910052593 corundum Inorganic materials 0.000 claims 1
- 239000000377 silicon dioxide Substances 0.000 claims 1
- 235000012239 silicon dioxide Nutrition 0.000 claims 1
- 229910001845 yogo sapphire Inorganic materials 0.000 claims 1
- 229910001338 liquidmetal Inorganic materials 0.000 abstract 1
- 239000000047 product Substances 0.000 description 14
- 238000005266 casting Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 238000011282 treatment Methods 0.000 description 5
- 150000001875 compounds Chemical class 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 238000003475 lamination Methods 0.000 description 3
- 230000000930 thermomechanical effect Effects 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000010348 incorporation Methods 0.000 description 2
- 238000005551 mechanical alloying Methods 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 229910021332 silicide Inorganic materials 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- UHZZMRAGKVHANO-UHFFFAOYSA-M chlormequat chloride Chemical compound [Cl-].C[N+](C)(C)CCCl UHZZMRAGKVHANO-UHFFFAOYSA-M 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000007669 thermal treatment Methods 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- 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
- B22D11/108—Feeding additives, powders, or the like
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Powder Metallurgy (AREA)
- Forging (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
Abstract
The invention concerns a method for continuous casting of a metal in the form of a hollow jet into a nozzle arranged between a pouring ladle or a tundish and a continuous casting ingot mold, said nozzle including in its upper part a dispensing member capable of deflecting at least part of the liquid metal reaching the nozzle inlet towards an inner wall of the nozzle before it penetrates into the ingot mold. Said method includes injecting into an inner volume of the hollow jet finely-divided solid material, characterized in that the finely-divided solid material comprises technical ceramic nanoparticles, of characteristic size less than 200 nm and preferably less than 100 nm.
Description
= CA 02599440 2007-08-28 CAMM2746W0 (English translation of PCT application as filed).doc = WO 2006/096942 METHOD FOR THE CONTINUOUS CASTING OF A METAL WITH IMPROVED
MECHANICAL STRENGTH AND PRODUCT OBTAINED BY THE METHOD
Field of the invention [0001] The present invention relates to a new method for the continuous casting of a molten metal, in particular steel, that allows to obtain an intermediate product such as a slab, billet, wire, etc. before subsequent thermomechanical treatment such as lamination, continuous annealing, etc., such that its chemical composition is modified by the addition of elements in order to give it greater mechanical strength.
15 [0002] The following description makes more specific reference to the continuous casting of steel. However, this choice is only an example and does not entail any limitation of the invention.
[0003] The invention also relates to the product with improved mechanical features obtained by the method.
State of the art [0004] The technique of the continuous casting of steel is well known. It essentially consists in feeding molten steel from a ladle or from a tundish into a cooled copper or copper-alloy mould called "continuous casting ingot mould", the latter being open at its bottom end, and in extracting from this opening an ingot in the form of a partly solidified continuous sheet.
30 [0005] In general, the molten steel is fed into the ingot mould by means of at least one nozzle, i.e. a generally tubular element positioned between the tundish and the ingot mould. The bottom end of the nozzle is usually provided with one or two outlet apertures located on the axis of the nozzle = CA 02599440 2012-12-28 .
= =
.
=
or on the sides, and cbmes out belbw the level that is free = . of molten steel present in the ingot' mould.
[0006] Figure 1 shows a casting device as in the state of the art (patent BE 1014063) fitted between a continuous casting mould 1 .5 and a casting ladle or tundish 2 with an outlet pipe 3.
The outlet pipe 3 is equipped with a flow regulator such as a stopper 4 or a sliding tray. A nozzle 5, essentially in the form of a cylinder and possibly with an oval cross-section, attached to the fl tundish, is positioned .above the mould 1 and plunges into it.
The top base of the cylinder is in contact with the pipe 3. This base is equipped with an aperture matching the inner aperture of the pipe. The nozzle 5 comprises in its lower part at least one = communication eye 8 to allow the steel to pass through to the mould.
In the upper part of the nozzle 5, there is a distribution device in the form of a dome 6, whose top surface is -slightly sloped, preferably at an angle greater than 100 relative to the horizontal. An injection device is positioned in such a way as to introduce finely divided solid particles or particles in powder form 15 under the dome 6, using a non-oxidizing gas as a vector. This device also comprises an incoming flow of argon 7 and its device for measuring flow rate 9 and pressure 10, a container for powder or finely divided particles 11 and its weight-measurement device 12, and lastly a supplier pipe in the nozzle 13, as well as an injector 14.
[0007]
Developments of the nozzles are also known that are intended to achieve improved cooling of the too-hot molten steel coming from the tundish. The aim is to obtain steel 'the form of a 'paste upon its entry into the ingot mould. These nozzles may, it particular comprise a heat exchanger with a water-cooled copper tube or even a. deflector , or a dome. The latter has the purpOse of forcing -the fl .30 overheated steel to trickle down.in a thin layer along the _ =
-walls of the nbzzle',- which' allows tici significantly increase the area of thermal exchange. The cooling of the conduit - ensures the removal of the excess heat from the Steel- and .
=
=
. .
=
= =
2a causes the appearance of a solid fraction which turns the steel into a paste upon its entry into the ingot mould. The introduction of a protective gas under pressure, for example argon, in the conduit causes an overload that prevents any air flow by the molten steel, which would lead to its oxidisation or to the formation of alumina and the clogging of the nozzle. This technique described in patent EP-B-269-180 is called casting with a hollow jet or by means' of a 1-1L7N
or hollow jet nozzle.
Another development, described in patent EP-B-6-05 379, relates to the injection into the hollow jet of some quantity of finely divided metal material by using a non-oxidising gas as a vector at a slightly higher pressirre relative to atmospheric -pressure in order to prevent any entry. of air. Depending on the case, the aim is to obtain refinement of the solidification structure by creating new solidification seeds or a modification of the basic chemical composition of the steel.
[0008] A continuous casting nozzle with a rotating jet is also known, as described in patent BE-A-101 20 37, and composed of a vertical conduit with a distribution device or =
= CA 02599440 2007-08-28 dome in its upper part, whose function is also to divert the metal entering the nozzle towards the internal surface of said conduit and which comprises three arms arranged in a star pattern relative to the nozzle axis and canted relative to the horizontal. These arms are configured so as to impart a helicoidal rotary motion along the inner wall to the molten steel. The molten steel then comes out through two side outlets in the nozzle at a speed that is significantly lower than that obtained with a conventional nozzle with the same flow, which improves the quality of the ingots extracted (less inclusions and less gas bubbles).
[0009]
The continuous casting of steel-based products with a mixed chemical or bi-component composition has also aroused great interest in a large number of specific applications, both for long and flat products (for example reduction of the silicon level at the surface of the slabs, in order to improve the suitability of laminated products to galvanisation; modification of the carbon content at the surface of peritectic steels to improve their casting flow;
casting of products whose mechanical properties vary along their thicknesses, such as for instance great strength at the surfaces and high ductility in the cores, etc.). The term bi-component refers to products with a chemical composition of steel that varies depending on its position in the product studied, for example varying in the skin compared with the core. To meet this requirement, the Applicant proposed in international patent application WO-A-02/30598 a continuous casting nozzle comprising a distribution device with a dome in its top part, designed to separate the molten steel into two streams, an inner stream and an outer stream, in two physically well-separated zones. A means for injecting a gas, liquid or finely divided solid material (a powder with a particle size typically greater than 100 microns) under the dome into the inner zone allows the formation of a steel with = CA 02599440 2007-08-28 a chemical composition that is different to that of the basic steel, cast in the outer zone.
[0010] In addition, it is known that traditional thermomechanical treatments aimed at improving the mechanical features of a steel, for example by its microstructure (martensite, bainite, etc.) or by endogenous precipitation, have the drawback that the structure of the steel finally obtained may be adversely affected by thermal post-treatment of the product (for example welding, galvanisation, etc.). It would therefore be desirable, at least in some cases, to be able to cast directly a product with a structure, and hence mechanical properties, that are stable throughout any subsequent treatment that the product might undergo.
Aims of the invention [0011] The present invention aims to provide a solution that allows to overcome the drawbacks of the state of the art.
[0012] The present invention aims in particular to provide a method of continuous casting that allows to produce slabs or billets of a modified chemical composition adapted to give the steel greater mechanical strength before lamination.
[0013] The invention notably aims to obtain a steel of homogeneous chemical composition and/or stabilised structure relative to a lamination process and/or thermomechanical treatment subsequent to casting.
[0014] One particular aim of the present invention is to exploit the hollow-jet technique in order to inject finely divided ceramic particles through the continuous casting nozzle.
fl CA 02599440 2007-08-28 Main characteristic elements of the invention [0015] A first aim of the present invention relates to a method for the continuous casting of a metal, in the form of a hollow jet in a nozzle positioned between a ladle or a 5 tundish and a continuous casting ingot mould, said nozzle comprising in its upper part a distribution device capable of diverting at least part of the molten metal arriving at the inlet of the nozzle towards an inner wall in the nozzle before it enters the ingot mould, said method comprising the injection in an internal volume of the hollow jet of finely divided solid material, characterised in that the finely divided solid material comprises nanoparticles of technical ceramic, of a characteristic size lower than 200nm, and preferably lower than 100nm.
15 [0016] Advantageously, the nanoparticles of technical ceramic comprise nanoparticles of oxides, nitrides, carbides, borides, silicides and/or compounds thereof.
[0017] The oxides are preferably A1203, Ti02, Si02, MgO, Zr02 or Y203.
20 [0018] As a further advantage, the size of the nanoparticles is between 10 and 100nm.
[0019] Still according to the invention, the quantity of nanoparticles incorporated into the molten metal is lower than or equal to 5%, and preferably between 0.1 and 1% by 25 weight of cast metal.
[0020] According to a preferred embodiment of the invention, the ceramic nanoparticles injected into the internal volume of the hollow jet of the nozzle are in suspension in a non-oxidising gas, preferably argon, said gas 30 being at slightly higher pressure relative to atmospheric pressure and at most equal to the static pressure of the cast metal upon its entry into the ingot mould.
[0021] According to another preferred embodiment of the invention, the ceramic nanoparticles are injected into the internal volume of the hollow jet of the nozzle by means of a mechanical conveyance device such as a worm screw.
[0022] As a particular advantage, the nanoparticles are conglomerated prior to their injection into the nozzle into microparticles of a size essentiallyy between 10 and 1,000 microns, and preferably between 100 and 200 microns.
[0023] Still advantageously, prior to their injection into the nozzle, the nanoparticles are conglomerated into a metal matrix made of the same metal or of a different metal to the cast metal.
[0024] The cast metal is preferably molten steel and the metal matrix is an iron matrix or the metal matrix comprises a alloy metal other than iron.
[0025] As a further advantage, the conglomeration of the nanoparticles is obtained by mixing ceramic nanoparticles with micrometric iron particles, i.e. particles of a size greater than 10 microns, and preferably less than 20 microns.
[0026] According to a first preferred method, said mixture is produced by a pre-mix in a slurry, followed by drying, crushing, isostatic pressing and further crushing.
[0027] According to a second preferred method, said mixture is produced by high-energy tapping of the type "mechanical alloying" so as to incorporate the ceramics into the iron matrix.
[0028] According to a first advantageous embodiment, the hollow-jet nozzle used is of the type rotating jet, i.e.
it comprises a vertical conduit having a distribution device with a dome in its upper part, whose function is to divert the molten metal entering the nozzle towards the internal surface of said conduit and which comprises a series of arms arranged symmetrically in a star pattern relative to the axis of the nozzle and canted relative to the horizontal, said arms being arranged to impart a helicoidal rotary motion to the molten steel along the inner wall of the nozzle.
= CA 02599440 2007-08-28 [0029] According to another advantageous embodiment, the hollow-jet nozzle used comprises a distribution device with a dome in its upper part designed to separate the molten metal into two streams, an inner stream and an outer stream, in two physically well-separated zones, the injection of ceramic nanoparticles under the dome in the inner zone allowing the formation of a metal with a different chemical composition to that of the basic metal, cast in the outer zone.
10 [0030] Alternatively, the injection of ceramic nanoparticles may be carried out in the outer zone of the nozzle.
[0031] A second aim of the present invention relates to a metal, preferably steel, with high mechanical strength and taking the form after casting of an ingot in a continuous sheet upon its exit from a continuous casting ingot mould, specifically obtained by means of the above-described method and comprising less than one percent by weight of technical ceramic homogeneously distributed in at least one part of the ingot.
Description of a preferred embodiment of the invention [0032] The idea on which the invention is based is to develop a steel hardened by a fine dispersion of ceramic particles that give the steel stable properties that do not deteriorate because of subsequent thermal treatment(s).
[0033] By way of an example, the case of the continuous casting of steel will be considered.
[0034] It is therefore proposed to cast a standard basic steel to which is added, as required, a quantity of particles needed to obtain the strength properties desired.
As an advantage, the addition of particles to the molten metal is carried out directly at the level of the continuous casting nozzle since the latter, in the embodiments generally used and described above, generally comprises a means for inserting alloy elements or oxides in at least one fraction of the molten metal passing through the nozzle.
[0035] According to the invention, the particles added are ceramic particles. The man skilled in the art knows that technical or industrial ceramics refer to a class of manufactured materials that are non-metallic and inorganic.
They are divided into two main groups: the oxides (for example A1203, Ti02, Si02, MgO, Zr02, Y203, etc.) and the non-oxides (nitrides, carbides, borides, silicides, etc.).
Moreover, for the requirements of the invention, the ceramic particles must comply with the following operational definition: they are of a nanometric size, typically 10-100 nanometres (1nm = 10-9m), and after incorporation into the molten steel, they are essentially homogeneously distributed throughout the entire section of the cast product. The "size"
of the particles is meant here as the largest dimension of the particle. The nanometric nature of the particles for inclusion is in fact indispensable to the reinforcement of the product. By contrast, micrometric inclusions constitute defects, heterogeneous areas that make the product weaker.
[0036] The quantities of nanoparticles added to the molten steel are maximum 1% by weight.
[0037] The wettability of the particles in the molten steel is the most important criterion for the choice of particles and the resolution of this technical problem is at the heart of the present invention. Homogeneous distribution of the nanoparticles in the molten steel is indispensable, which excludes confinement of the powders injected to the surface of the molten steel.
[0038] According to the invention, the particles may advantageously be conglomerated up to a size of 100-20011m so as to be able to be injected through the HJN nozzle.
[0039] To improve the wettability of the particles in the molten steel, the nanometric ceramic particles may be conglomerated in an iron or metal matrix to obtain a compound whose characteristic final size is 100-200pm. The iron or metal matrix favours the dispersion of the particles in the molten steel. In order to obtain this compound, nanometric ceramic particles are used mixed with micrometric iron particles (whose size is for example 10 to 20 microns). The mixture is produced either by:
- mixing into a slurry and then drying, crushing, isostatic pressing and then re-crushing;
- high-energy tapping (mechanical alloying) to ensure that the ceramics are incorporated into the iron matrix.
Tapping is an operation that consists in bringing an element into contact and introducing it into a combination formed of one or several elements that are different from the first element by exerting a force on the element.
[0040] Advantageously, these compounds are injected under gaseous atmosphere in the HJN nozzle (see patent EP-B-605 379). The heavy turbulence occurring in the nozzle thus allows good incorporation of the particles into the molten steel.
MECHANICAL STRENGTH AND PRODUCT OBTAINED BY THE METHOD
Field of the invention [0001] The present invention relates to a new method for the continuous casting of a molten metal, in particular steel, that allows to obtain an intermediate product such as a slab, billet, wire, etc. before subsequent thermomechanical treatment such as lamination, continuous annealing, etc., such that its chemical composition is modified by the addition of elements in order to give it greater mechanical strength.
15 [0002] The following description makes more specific reference to the continuous casting of steel. However, this choice is only an example and does not entail any limitation of the invention.
[0003] The invention also relates to the product with improved mechanical features obtained by the method.
State of the art [0004] The technique of the continuous casting of steel is well known. It essentially consists in feeding molten steel from a ladle or from a tundish into a cooled copper or copper-alloy mould called "continuous casting ingot mould", the latter being open at its bottom end, and in extracting from this opening an ingot in the form of a partly solidified continuous sheet.
30 [0005] In general, the molten steel is fed into the ingot mould by means of at least one nozzle, i.e. a generally tubular element positioned between the tundish and the ingot mould. The bottom end of the nozzle is usually provided with one or two outlet apertures located on the axis of the nozzle = CA 02599440 2012-12-28 .
= =
.
=
or on the sides, and cbmes out belbw the level that is free = . of molten steel present in the ingot' mould.
[0006] Figure 1 shows a casting device as in the state of the art (patent BE 1014063) fitted between a continuous casting mould 1 .5 and a casting ladle or tundish 2 with an outlet pipe 3.
The outlet pipe 3 is equipped with a flow regulator such as a stopper 4 or a sliding tray. A nozzle 5, essentially in the form of a cylinder and possibly with an oval cross-section, attached to the fl tundish, is positioned .above the mould 1 and plunges into it.
The top base of the cylinder is in contact with the pipe 3. This base is equipped with an aperture matching the inner aperture of the pipe. The nozzle 5 comprises in its lower part at least one = communication eye 8 to allow the steel to pass through to the mould.
In the upper part of the nozzle 5, there is a distribution device in the form of a dome 6, whose top surface is -slightly sloped, preferably at an angle greater than 100 relative to the horizontal. An injection device is positioned in such a way as to introduce finely divided solid particles or particles in powder form 15 under the dome 6, using a non-oxidizing gas as a vector. This device also comprises an incoming flow of argon 7 and its device for measuring flow rate 9 and pressure 10, a container for powder or finely divided particles 11 and its weight-measurement device 12, and lastly a supplier pipe in the nozzle 13, as well as an injector 14.
[0007]
Developments of the nozzles are also known that are intended to achieve improved cooling of the too-hot molten steel coming from the tundish. The aim is to obtain steel 'the form of a 'paste upon its entry into the ingot mould. These nozzles may, it particular comprise a heat exchanger with a water-cooled copper tube or even a. deflector , or a dome. The latter has the purpOse of forcing -the fl .30 overheated steel to trickle down.in a thin layer along the _ =
-walls of the nbzzle',- which' allows tici significantly increase the area of thermal exchange. The cooling of the conduit - ensures the removal of the excess heat from the Steel- and .
=
=
. .
=
= =
2a causes the appearance of a solid fraction which turns the steel into a paste upon its entry into the ingot mould. The introduction of a protective gas under pressure, for example argon, in the conduit causes an overload that prevents any air flow by the molten steel, which would lead to its oxidisation or to the formation of alumina and the clogging of the nozzle. This technique described in patent EP-B-269-180 is called casting with a hollow jet or by means' of a 1-1L7N
or hollow jet nozzle.
Another development, described in patent EP-B-6-05 379, relates to the injection into the hollow jet of some quantity of finely divided metal material by using a non-oxidising gas as a vector at a slightly higher pressirre relative to atmospheric -pressure in order to prevent any entry. of air. Depending on the case, the aim is to obtain refinement of the solidification structure by creating new solidification seeds or a modification of the basic chemical composition of the steel.
[0008] A continuous casting nozzle with a rotating jet is also known, as described in patent BE-A-101 20 37, and composed of a vertical conduit with a distribution device or =
= CA 02599440 2007-08-28 dome in its upper part, whose function is also to divert the metal entering the nozzle towards the internal surface of said conduit and which comprises three arms arranged in a star pattern relative to the nozzle axis and canted relative to the horizontal. These arms are configured so as to impart a helicoidal rotary motion along the inner wall to the molten steel. The molten steel then comes out through two side outlets in the nozzle at a speed that is significantly lower than that obtained with a conventional nozzle with the same flow, which improves the quality of the ingots extracted (less inclusions and less gas bubbles).
[0009]
The continuous casting of steel-based products with a mixed chemical or bi-component composition has also aroused great interest in a large number of specific applications, both for long and flat products (for example reduction of the silicon level at the surface of the slabs, in order to improve the suitability of laminated products to galvanisation; modification of the carbon content at the surface of peritectic steels to improve their casting flow;
casting of products whose mechanical properties vary along their thicknesses, such as for instance great strength at the surfaces and high ductility in the cores, etc.). The term bi-component refers to products with a chemical composition of steel that varies depending on its position in the product studied, for example varying in the skin compared with the core. To meet this requirement, the Applicant proposed in international patent application WO-A-02/30598 a continuous casting nozzle comprising a distribution device with a dome in its top part, designed to separate the molten steel into two streams, an inner stream and an outer stream, in two physically well-separated zones. A means for injecting a gas, liquid or finely divided solid material (a powder with a particle size typically greater than 100 microns) under the dome into the inner zone allows the formation of a steel with = CA 02599440 2007-08-28 a chemical composition that is different to that of the basic steel, cast in the outer zone.
[0010] In addition, it is known that traditional thermomechanical treatments aimed at improving the mechanical features of a steel, for example by its microstructure (martensite, bainite, etc.) or by endogenous precipitation, have the drawback that the structure of the steel finally obtained may be adversely affected by thermal post-treatment of the product (for example welding, galvanisation, etc.). It would therefore be desirable, at least in some cases, to be able to cast directly a product with a structure, and hence mechanical properties, that are stable throughout any subsequent treatment that the product might undergo.
Aims of the invention [0011] The present invention aims to provide a solution that allows to overcome the drawbacks of the state of the art.
[0012] The present invention aims in particular to provide a method of continuous casting that allows to produce slabs or billets of a modified chemical composition adapted to give the steel greater mechanical strength before lamination.
[0013] The invention notably aims to obtain a steel of homogeneous chemical composition and/or stabilised structure relative to a lamination process and/or thermomechanical treatment subsequent to casting.
[0014] One particular aim of the present invention is to exploit the hollow-jet technique in order to inject finely divided ceramic particles through the continuous casting nozzle.
fl CA 02599440 2007-08-28 Main characteristic elements of the invention [0015] A first aim of the present invention relates to a method for the continuous casting of a metal, in the form of a hollow jet in a nozzle positioned between a ladle or a 5 tundish and a continuous casting ingot mould, said nozzle comprising in its upper part a distribution device capable of diverting at least part of the molten metal arriving at the inlet of the nozzle towards an inner wall in the nozzle before it enters the ingot mould, said method comprising the injection in an internal volume of the hollow jet of finely divided solid material, characterised in that the finely divided solid material comprises nanoparticles of technical ceramic, of a characteristic size lower than 200nm, and preferably lower than 100nm.
15 [0016] Advantageously, the nanoparticles of technical ceramic comprise nanoparticles of oxides, nitrides, carbides, borides, silicides and/or compounds thereof.
[0017] The oxides are preferably A1203, Ti02, Si02, MgO, Zr02 or Y203.
20 [0018] As a further advantage, the size of the nanoparticles is between 10 and 100nm.
[0019] Still according to the invention, the quantity of nanoparticles incorporated into the molten metal is lower than or equal to 5%, and preferably between 0.1 and 1% by 25 weight of cast metal.
[0020] According to a preferred embodiment of the invention, the ceramic nanoparticles injected into the internal volume of the hollow jet of the nozzle are in suspension in a non-oxidising gas, preferably argon, said gas 30 being at slightly higher pressure relative to atmospheric pressure and at most equal to the static pressure of the cast metal upon its entry into the ingot mould.
[0021] According to another preferred embodiment of the invention, the ceramic nanoparticles are injected into the internal volume of the hollow jet of the nozzle by means of a mechanical conveyance device such as a worm screw.
[0022] As a particular advantage, the nanoparticles are conglomerated prior to their injection into the nozzle into microparticles of a size essentiallyy between 10 and 1,000 microns, and preferably between 100 and 200 microns.
[0023] Still advantageously, prior to their injection into the nozzle, the nanoparticles are conglomerated into a metal matrix made of the same metal or of a different metal to the cast metal.
[0024] The cast metal is preferably molten steel and the metal matrix is an iron matrix or the metal matrix comprises a alloy metal other than iron.
[0025] As a further advantage, the conglomeration of the nanoparticles is obtained by mixing ceramic nanoparticles with micrometric iron particles, i.e. particles of a size greater than 10 microns, and preferably less than 20 microns.
[0026] According to a first preferred method, said mixture is produced by a pre-mix in a slurry, followed by drying, crushing, isostatic pressing and further crushing.
[0027] According to a second preferred method, said mixture is produced by high-energy tapping of the type "mechanical alloying" so as to incorporate the ceramics into the iron matrix.
[0028] According to a first advantageous embodiment, the hollow-jet nozzle used is of the type rotating jet, i.e.
it comprises a vertical conduit having a distribution device with a dome in its upper part, whose function is to divert the molten metal entering the nozzle towards the internal surface of said conduit and which comprises a series of arms arranged symmetrically in a star pattern relative to the axis of the nozzle and canted relative to the horizontal, said arms being arranged to impart a helicoidal rotary motion to the molten steel along the inner wall of the nozzle.
= CA 02599440 2007-08-28 [0029] According to another advantageous embodiment, the hollow-jet nozzle used comprises a distribution device with a dome in its upper part designed to separate the molten metal into two streams, an inner stream and an outer stream, in two physically well-separated zones, the injection of ceramic nanoparticles under the dome in the inner zone allowing the formation of a metal with a different chemical composition to that of the basic metal, cast in the outer zone.
10 [0030] Alternatively, the injection of ceramic nanoparticles may be carried out in the outer zone of the nozzle.
[0031] A second aim of the present invention relates to a metal, preferably steel, with high mechanical strength and taking the form after casting of an ingot in a continuous sheet upon its exit from a continuous casting ingot mould, specifically obtained by means of the above-described method and comprising less than one percent by weight of technical ceramic homogeneously distributed in at least one part of the ingot.
Description of a preferred embodiment of the invention [0032] The idea on which the invention is based is to develop a steel hardened by a fine dispersion of ceramic particles that give the steel stable properties that do not deteriorate because of subsequent thermal treatment(s).
[0033] By way of an example, the case of the continuous casting of steel will be considered.
[0034] It is therefore proposed to cast a standard basic steel to which is added, as required, a quantity of particles needed to obtain the strength properties desired.
As an advantage, the addition of particles to the molten metal is carried out directly at the level of the continuous casting nozzle since the latter, in the embodiments generally used and described above, generally comprises a means for inserting alloy elements or oxides in at least one fraction of the molten metal passing through the nozzle.
[0035] According to the invention, the particles added are ceramic particles. The man skilled in the art knows that technical or industrial ceramics refer to a class of manufactured materials that are non-metallic and inorganic.
They are divided into two main groups: the oxides (for example A1203, Ti02, Si02, MgO, Zr02, Y203, etc.) and the non-oxides (nitrides, carbides, borides, silicides, etc.).
Moreover, for the requirements of the invention, the ceramic particles must comply with the following operational definition: they are of a nanometric size, typically 10-100 nanometres (1nm = 10-9m), and after incorporation into the molten steel, they are essentially homogeneously distributed throughout the entire section of the cast product. The "size"
of the particles is meant here as the largest dimension of the particle. The nanometric nature of the particles for inclusion is in fact indispensable to the reinforcement of the product. By contrast, micrometric inclusions constitute defects, heterogeneous areas that make the product weaker.
[0036] The quantities of nanoparticles added to the molten steel are maximum 1% by weight.
[0037] The wettability of the particles in the molten steel is the most important criterion for the choice of particles and the resolution of this technical problem is at the heart of the present invention. Homogeneous distribution of the nanoparticles in the molten steel is indispensable, which excludes confinement of the powders injected to the surface of the molten steel.
[0038] According to the invention, the particles may advantageously be conglomerated up to a size of 100-20011m so as to be able to be injected through the HJN nozzle.
[0039] To improve the wettability of the particles in the molten steel, the nanometric ceramic particles may be conglomerated in an iron or metal matrix to obtain a compound whose characteristic final size is 100-200pm. The iron or metal matrix favours the dispersion of the particles in the molten steel. In order to obtain this compound, nanometric ceramic particles are used mixed with micrometric iron particles (whose size is for example 10 to 20 microns). The mixture is produced either by:
- mixing into a slurry and then drying, crushing, isostatic pressing and then re-crushing;
- high-energy tapping (mechanical alloying) to ensure that the ceramics are incorporated into the iron matrix.
Tapping is an operation that consists in bringing an element into contact and introducing it into a combination formed of one or several elements that are different from the first element by exerting a force on the element.
[0040] Advantageously, these compounds are injected under gaseous atmosphere in the HJN nozzle (see patent EP-B-605 379). The heavy turbulence occurring in the nozzle thus allows good incorporation of the particles into the molten steel.
Claims (15)
1. A method for the continuous casting of metal in the form of a hollow jet in a nozzle positioned between a ladle or a tundish and a continuous casting ingot mould, said nozzle comprising in its upper part a distribution device capable of diverting at least part of the molten metal arriving at the inlet of the nozzle towards an inner wall of the nozzle before it enters the ingot mould, said method comprises the injection into an internal volume of the hollow jet of finely divided solid material comprising nanoparticles of technical ceramic with a characteristic size lower than 200nm, said nanoparticles being conglomerated prior to their injection into the nozzle into microparticles in a metal matrix, said microparticles having a size between 10 and 1,000 microns, characterised in that said nanoparticles are oxide nanoparticles selected form the group consisting of Al2O3, TiO2, SiO2, MgO, ZrO2 or Y2O3, said metal is molten steel and wherein said nanoparticles are incorporated in a quantity between 0.1% and 1% by weight of the casted molten metal.
2. The method according to claim 1, characterised in that the characteristic size of the nanoparticles is lower than 100nm.
3. The method according to claim 2, characterised in that the size of the nanoparticles is between 10 and 100nm.
4. The method according to any one of claims 1, 2 or 3, characterised in that the size of the microparticles is between 100 and 200 microns.
5. The method according to any one of claims 1 to 4, characterised in that the conglomerated ceramic nanoparticles injected into the inner volume of the hollow jet of the nozzle are in suspension in a non-oxidising gas, said gas being at a slightly higher pressure relative to atmospheric pressure and at most equal to the static pressure of the cast metal upon its entry into the ingot mould.
6. The method according to any one of claims 1 to 4, characterised in that the conglomerated ceramic nanoparticles are injected into the inner volume of the hollow jet of the nozzle by means of a mechanical conveyance device.
7. The method according to any one of claims 1 to 6, characterised in that the metal matrix is an iron matrix.
8. The method according to claim 7, characterised in that the metal matrix comprises an alloy metal other than iron.
9. The method according to claim 7 or 8, characterised in that the conglomeration of the nanoparticles is obtained by mixing ceramic nanoparticles with micrometric iron particles having a size greater than 10 microns.
10. The method according to claim 9, characterised in that said micrometric iron particles have a size lower than 20 microns.
11. The method according to claim 9 or 10, characterised in that said mixture is produced by a premix in a slurry, followed by drying, crushing, isostatic pressing and re-crushing.
12. The method according to claim 9 or 10, characterised in that said mixture is produced by high-energy tapping to ensure that the ceramics are incorporated into the iron matrix.
13. The method according to any one of claims 1 to 12, characterised in that the hollow jet nozzle used is of the rotary jet type, comprising a vertical conduit having a distribution device with a dome in its upper part, whose function is to divert the molten metal entering the nozzle towards the inner surface of said conduit and which comprises a series of arms symmetrically arranged in a star pattern relative to the axis of the nozzle and canted relative to the horizontal, said arms being arranged to impart a helicoidal rotary motion to the molten steel along the internal wall of the nozzle.
14. The method according to any one of claims 1 to 12, characterised in that the hollow jet nozzle used comprises in its upper part a distribution device with a dome designed to separate the molten metal into two streams, an inner stream and an outer stream, in two physically well-separated zones, the injection of ceramic nanoparticles under the dome in the inner zone allowing the formation of a metal with a different chemical composition to that of the basic metal, cast in the outer zone.
15. The method according to claim 14, characterised in that the injection of ceramic nanoparticles is alternatively produced in the outer zone.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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BE2005/0139A BE1016550A3 (en) | 2005-03-16 | 2005-03-16 | Process for casting continuous metal mechanical resistance and improved product obtained by the process. |
BE2005/0139 | 2005-03-16 | ||
PCT/BE2006/000003 WO2006096942A1 (en) | 2005-03-16 | 2006-01-19 | Method for continuous casting of a metal with improved mechanical strength and product obtained by said method |
Publications (2)
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CA2599440A1 CA2599440A1 (en) | 2006-09-21 |
CA2599440C true CA2599440C (en) | 2014-08-19 |
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CA2599440A Expired - Fee Related CA2599440C (en) | 2005-03-16 | 2006-01-19 | Method for the continuous casting of a metal with improved mechanical strength and product obtained by the method |
Country Status (10)
Country | Link |
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US (1) | US20090266506A1 (en) |
EP (1) | EP1858662B1 (en) |
JP (1) | JP4906840B2 (en) |
KR (1) | KR101257326B1 (en) |
AT (1) | ATE485906T1 (en) |
BE (1) | BE1016550A3 (en) |
CA (1) | CA2599440C (en) |
DE (1) | DE602006017811D1 (en) |
ES (1) | ES2351886T3 (en) |
WO (1) | WO2006096942A1 (en) |
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US9004150B2 (en) | 2005-03-16 | 2015-04-14 | Centre de Recherches Metallurgiques ASBL—Centrum Voor Research in de Metallurgie VZW | Method for continuous casting of a metal with improved mechanical strength and product obtained by said method |
BE1017392A3 (en) * | 2006-12-12 | 2008-08-05 | Ct Rech Metallurgiques Asbl | HOLLOW JET BUSHET FOR CONTINUOUS STEEL CASTING. |
EP2047926A1 (en) | 2007-10-10 | 2009-04-15 | Ugine & Alz France | Method of manufacturing stainless steels comprising fine carbonitrides, and product obtained from this method |
KR101269451B1 (en) * | 2011-06-27 | 2013-05-30 | 연세대학교 산학협력단 | Oxygen atoms-dispersed metal-based composite material and method for manufacturing the same |
EP2830792B1 (en) * | 2012-03-28 | 2019-02-20 | ArcelorMittal | Continuous casting process of metal |
CN103243194B (en) * | 2013-05-31 | 2015-01-21 | 安徽工业大学 | Method for optimizing steel structure by adding nano particles into steel liquid |
Family Cites Families (10)
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FR2656551A1 (en) * | 1990-01-04 | 1991-07-05 | Pechiney Recherche | METHOD AND DEVICE FOR THE CONTINUOUS CASTING OF METALLIC REINFORCED METALLIC MATRIX COMPOSITES OF A REFRACTORY CERAMIC MATERIAL. |
JP2863675B2 (en) * | 1992-09-01 | 1999-03-03 | 井上 明久 | Manufacturing method of particle reinforced composite material |
BE1006567A6 (en) * | 1992-12-28 | 1994-10-18 | Centre Rech Metallurgique | Casting process of metal phase pasty. |
JP3426425B2 (en) * | 1995-10-05 | 2003-07-14 | 新日本製鐵株式会社 | Slab for refractory rolled section steel and method for producing refractory rolled section steel from the same |
US6162530A (en) * | 1996-11-18 | 2000-12-19 | University Of Connecticut | Nanostructured oxides and hydroxides and methods of synthesis therefor |
BE1012037A3 (en) * | 1998-06-11 | 2000-04-04 | Centre Rech Metallurgique | Nozzle for continuous pouring of steel |
US6251159B1 (en) * | 1998-12-22 | 2001-06-26 | General Electric Company | Dispersion strengthening by nanophase addition |
BE1013745A3 (en) * | 2000-10-10 | 2002-07-02 | Ct De Rech S Metallurg Ass San | Method and device for casting continuous steel chemical composition a mixed. |
DE10253577B4 (en) * | 2002-11-15 | 2011-05-19 | Ab Skf | Process for producing a dispersion-hardened iron material |
US7235118B2 (en) * | 2003-04-16 | 2007-06-26 | National Research Council Of Canada | Process for agglomeration and densification of nanometer sized particles |
-
2005
- 2005-03-16 BE BE2005/0139A patent/BE1016550A3/en not_active IP Right Cessation
-
2006
- 2006-01-19 AT AT06701517T patent/ATE485906T1/en active
- 2006-01-19 KR KR1020077021254A patent/KR101257326B1/en not_active IP Right Cessation
- 2006-01-19 US US11/883,979 patent/US20090266506A1/en not_active Abandoned
- 2006-01-19 DE DE602006017811T patent/DE602006017811D1/en active Active
- 2006-01-19 ES ES06701517T patent/ES2351886T3/en active Active
- 2006-01-19 WO PCT/BE2006/000003 patent/WO2006096942A1/en active Search and Examination
- 2006-01-19 JP JP2008501114A patent/JP4906840B2/en not_active Expired - Fee Related
- 2006-01-19 CA CA2599440A patent/CA2599440C/en not_active Expired - Fee Related
- 2006-01-19 EP EP06701517A patent/EP1858662B1/en not_active Not-in-force
Also Published As
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US20090266506A1 (en) | 2009-10-29 |
JP2008532772A (en) | 2008-08-21 |
ATE485906T1 (en) | 2010-11-15 |
WO2006096942A1 (en) | 2006-09-21 |
BE1016550A3 (en) | 2007-01-09 |
KR101257326B1 (en) | 2013-04-24 |
JP4906840B2 (en) | 2012-03-28 |
EP1858662A1 (en) | 2007-11-28 |
DE602006017811D1 (en) | 2010-12-09 |
CA2599440A1 (en) | 2006-09-21 |
EP1858662B1 (en) | 2010-10-27 |
KR20070110368A (en) | 2007-11-16 |
ES2351886T3 (en) | 2011-02-11 |
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