CA1099891A - Process for the continuous casting of steel - Google Patents
Process for the continuous casting of steelInfo
- Publication number
- CA1099891A CA1099891A CA293,848A CA293848A CA1099891A CA 1099891 A CA1099891 A CA 1099891A CA 293848 A CA293848 A CA 293848A CA 1099891 A CA1099891 A CA 1099891A
- Authority
- CA
- Canada
- Prior art keywords
- casting
- mould
- molten metal
- steel
- phase mixture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 27
- 239000010959 steel Substances 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims abstract description 12
- 238000009749 continuous casting Methods 0.000 title claims abstract description 5
- 238000005266 casting Methods 0.000 claims abstract description 65
- 239000002184 metal Substances 0.000 claims abstract description 46
- 239000000203 mixture Substances 0.000 claims abstract description 35
- 239000007788 liquid Substances 0.000 claims abstract description 25
- 239000011261 inert gas Substances 0.000 claims abstract description 20
- 239000007787 solid Substances 0.000 claims abstract description 11
- 239000000126 substance Substances 0.000 claims abstract description 5
- 239000000725 suspension Substances 0.000 claims abstract description 5
- 238000000926 separation method Methods 0.000 claims abstract description 3
- 239000000843 powder Substances 0.000 claims description 39
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 229910001208 Crucible steel Inorganic materials 0.000 claims description 4
- 230000001050 lubricating effect Effects 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 238000005461 lubrication Methods 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 229910000915 Free machining steel Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000003534 oscillatory effect Effects 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000013528 metallic particle Substances 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000896693 Disa Species 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 206010037844 rash Diseases 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000009834 vaporization 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
- B22D11/11—Treating the molten metal
Abstract
ABSTRACT OF THE DISCLOSURE:
A process for the continuous casting of steel and employing an intermediate container with bottom-pouring means and a pass-mould, the surface of the molten metal in the mould being covered by a multi-phase mixture of liquid inert gas and a particulate substance. The process is characterized in that, during casting, the multi-phase mixture of liquid inert gas containing a suspension of solid bodies, which fuse after separation from the mixture when in contact with the molten steel, is applied directly to the surface of the molten metal in the mould.
A process for the continuous casting of steel and employing an intermediate container with bottom-pouring means and a pass-mould, the surface of the molten metal in the mould being covered by a multi-phase mixture of liquid inert gas and a particulate substance. The process is characterized in that, during casting, the multi-phase mixture of liquid inert gas containing a suspension of solid bodies, which fuse after separation from the mixture when in contact with the molten steel, is applied directly to the surface of the molten metal in the mould.
Description
~L~a9~
The invention relates to a process for the continuous casting of steel and employing an intermediate container with bottom-pouring means and a pass-mould, the surface of the molten metal in the mould being covered by a multi-phase mixture of liquid inert gas and a particulate substance.
In the continuous casting of steel it is known to place casting powder on the surface of the molten metal, that part of the powder that is in direc~ contact with the liquid steel melting and exercising a lubricating action between the forming strand and the wall of the mould. When casting products of larger size, a casting tube is customarily used in conjunction with cast-ing powder, which tube protects the steel, is introduced into the mould to extend below the level of the molten metal and, in the zone of that level separates the casting powder or layer of slag from the strand as it is being cast. When casting smaller sizes of product, e.g. billets, it is however hardly possible to use casting tubes since, because of the cross-sections in question and the necessary wall-thickness of the casting tube, there is too little space between the tube and the cooling wall of the mould. This results in the formation at this point of a bridge of unfused casting powder and/or of solidified steel which can lead to rupture of the casting operation. If howe~er casting is carried out using casting powder but without a casting tube, there results the disadvantage that particles of slag are drawn i~to the interior of the strand by the stream of molten steel, and the steel is thus contaminated. ~herefore, smaller sizes of product are normally cast using oil as the lubricant. In this system, on the one hand the surface of the molten metal in the mould is no longer protected against atmospheric oxygen, while on the other hand this leads to an u~satisfactory lubricating effect, par~icularly when casting free-cutting steels, since the oil is decomposed by the high temperature, and the carbon-containing residues do not provide sufficient lubrication. This results in surface defects which lead ~o cracks, particularly during further shaping operations such as rolliny and, possibly, drawing, and result in products that are unusable or are capable of meeting only lower quality standards. Furthermore, the effect of the oil can result in the occurence of what are known as pin-prick pores which likewise have a deleterious effect upon the surface of the strand. A further disadvantage encountered in the casting of free-cutting steels, especially lead-bearing steels, and when using oil resides in the fact that during casting intermittent small eruptions accompanied by spurts of hot mekal from the mould can occur, so that the men operating the installation are at risk.
When casting powder and a casting tube are used in the casting of larger sizes of product such as blooms and slabs one of the functions of the casting powder is to protect the surface of the molten metal in the mould against atmospheric oxygen and to absorb impurities contained in the molten steel.
The movements of the surface of the molten metal necessitate, for this purpose, a layer of casting powder having a thickness of
The invention relates to a process for the continuous casting of steel and employing an intermediate container with bottom-pouring means and a pass-mould, the surface of the molten metal in the mould being covered by a multi-phase mixture of liquid inert gas and a particulate substance.
In the continuous casting of steel it is known to place casting powder on the surface of the molten metal, that part of the powder that is in direc~ contact with the liquid steel melting and exercising a lubricating action between the forming strand and the wall of the mould. When casting products of larger size, a casting tube is customarily used in conjunction with cast-ing powder, which tube protects the steel, is introduced into the mould to extend below the level of the molten metal and, in the zone of that level separates the casting powder or layer of slag from the strand as it is being cast. When casting smaller sizes of product, e.g. billets, it is however hardly possible to use casting tubes since, because of the cross-sections in question and the necessary wall-thickness of the casting tube, there is too little space between the tube and the cooling wall of the mould. This results in the formation at this point of a bridge of unfused casting powder and/or of solidified steel which can lead to rupture of the casting operation. If howe~er casting is carried out using casting powder but without a casting tube, there results the disadvantage that particles of slag are drawn i~to the interior of the strand by the stream of molten steel, and the steel is thus contaminated. ~herefore, smaller sizes of product are normally cast using oil as the lubricant. In this system, on the one hand the surface of the molten metal in the mould is no longer protected against atmospheric oxygen, while on the other hand this leads to an u~satisfactory lubricating effect, par~icularly when casting free-cutting steels, since the oil is decomposed by the high temperature, and the carbon-containing residues do not provide sufficient lubrication. This results in surface defects which lead ~o cracks, particularly during further shaping operations such as rolliny and, possibly, drawing, and result in products that are unusable or are capable of meeting only lower quality standards. Furthermore, the effect of the oil can result in the occurence of what are known as pin-prick pores which likewise have a deleterious effect upon the surface of the strand. A further disadvantage encountered in the casting of free-cutting steels, especially lead-bearing steels, and when using oil resides in the fact that during casting intermittent small eruptions accompanied by spurts of hot mekal from the mould can occur, so that the men operating the installation are at risk.
When casting powder and a casting tube are used in the casting of larger sizes of product such as blooms and slabs one of the functions of the casting powder is to protect the surface of the molten metal in the mould against atmospheric oxygen and to absorb impurities contained in the molten steel.
The movements of the surface of the molten metal necessitate, for this purpose, a layer of casting powder having a thickness of
2 n approximately 1 cm. Only that part of the casting powder in direct contact with the surface of the molten metal liquefies and serves ~o carry out lubrication. A layer of caked casting powder is still present between this liquid layer and the pulver-ulent top layer. The oscillatory movement not only draws liquid but also caked and pul~erulent casting powder into the gap between the wall o the mould and the molten or solidified steel.
This mixture of casting powder has a less efficient lubricating effect than liquefied casting powder, and this results in a strand surface of poorer quality and having pronou~lced osciLlation marks and casting powder inclusions. Oscillation marks promo-te the formation of cracks and lead to increased scarfing losses.
In the case of stainless steels, casting powder inclusions lead to increased grinding losses.
It is also known to use a homogeneous multi-phase mixture when continuously casting a metal into a mould with the poured stream of metal open i.e~ uncovered. In this p~ocedure a particulate substance, for example particles of soot are introduced into a lique~ied inert gas and are intended to improve the lubricating effect along the wall o the mould. In this system, the multi-phase mixture is applicd to the poured stream of metal by what is known as a phase separator. By way o~ the poured stream of metal, i.e. along this s~ream, the multi-phase mixture reaches the surface of the molten metal in the mould and protects the metal against the action of the atmosphere. Because of the introduction of the multi-phase mixture into the mould by way of the poured stream of metal and particularly when fairly large quantities of particulate substance are used, the particles are carried into the casting head by this poured stream of metal, and this leads to impurities. Also, when using this procedure for applying the multi-phase mixture to the poured stream of metal, trouble can occur due to ex~ernal influences, such as for example draught. The solid particles of the multi-phase mixture block the relatively small openings in the nozzles o~ the phase separator so that the protective effect of tle poured stream is unsatisfactory and this has a disadvantageous effect on the quality of the cast material. In the case of larger sizes of product, even distribution of the multi-phase mixture and there~ore of the solid bodies over the surface of the tnolten metal in the mould by way of the poured stream is not ensured, and this leads to uneven lubrication along the wall of the mould. Wavering of the poured stream following bottom-pouring cannot be prevented for various reasons, for example irregularities in the pouring nozzles~ This can result in the phase separator being sprayed with steel and this leads to trouble in supplying the multi-phase \
~9~
mixture and to stoppages in the castin~ operation.
The object of the present invention is to provide a method of applying a multi-phase mixture that, on the one hand, ensures trouble-free feed of the mixture, and, on the other hand, results in a high ~egree of purity of the cast steel and an improved surface.
This object is achieved in that during casting, the - multi-phase mixture of liquid inert gas containing a suspension of solid bodies, which fuse after separation from the mix-ture when in contact with the molten steel, is applied directly to the surface of the molten metal in the mould.
Surprisingly, it has been found that the application of the multi-phase mixture directly to the surface of the molten metal can largely prevent non-metallic particles fxom being carxied into the casting head. The solid bodies only perform the function of providing lubrication which is improved by the fusing of these solid bodies. The inclusion of solid bodies in the surface of the strand can be prevented. The multi-phase mixture takes over the function oE providing protection against atmospheric oxygen. Troubles at the feed apparatus due to spatter from the poured stream can no longer occur.
According to one feature of the invention, in casting with an open stream of poured rnetal the multi-phase mixture is applied at a distance ~rom the poured stream that is greater than half the diameter o this stream. When the poured stream strikes the surface of the molten metal in the mould a wave is formed in the zone around the poured stream, and the height and flow of this wave form a small protective wall which prevents the solid bodies from entering the zone in the i~nedaite vicinity of the poured stream and from being carried ~y this stream into the casting head. The open stream of poured material between the intermediate conkainer and the surface of the molten metal is - :
. . , . , ' . - . ' '. . . ' . , : ' . : ,, . . . : ': ' . ' protected against atmospheric oxygen b~ the vaporizing inert gas.
The impact of the poured stream on the surface of the molten metal eliminates a large part of t~le kinetic energy, so that the depth of flow in the sump is reduced an~ this has a favourabl~
effect upon the quality of the cast steel.
When casting larger sizes of product and using an open poured stream and the downwardly directed flow necessitated thereby, pronounced cooling of the steel in the zone of the surface of the molten metal in the mould cannot be prevented, and this leads to the formation of a top crust and therefore to considera~le reduction in quality in the cast strand~ According to the invention, this disadvantage is eliminated in that the steel emerging from the pouring orifice in the bottom of the intermediate vessel is introduced into the mould below the surface of the molten metal and is caused to flow towards and along said surface.
In acGordance with a further feature of the invention, a quantity of 1~15 kg of liquid inert gas and a quantity of 0.01-0.2 kg of casting powder are provided as the multi-phase miY~ture for each tonne of cast steel. The small quantity of casting powder has the effect of permitting only liquid casting powder to reach the zone between the wall of the mould and the steeL, and this results in a good lubricating action. The gas present in the zone of the wall of the mould prevents casting powder, contained in the liquid nitrogen, from reaching the wall of the mould so that the oscillatory movement does not cause any unfused casting powder to become mixed with the liquid casting powder, and this prevents the powder form ~eing included in the surface of the strand. Thus, losses due to dressing operations, such as for example grinding losses in the case of stainless steel, are reduced. The liquid casting powder performs the additional function of adsorbing non-metallic inclusions rising to the surface of the molten metal. When casting billets it is . .". : :
. . .
. ' . '' ,,', :"
~A~
possible to dispense with oil lubrication and this leads to elimination of the above-descri~ed disa~vantages particularly when casting lead-bearing free-cutting steels~
In order to achieve an even distribution of the multi phase mixture over the su.rface of the molten metal when producing products of larger size, it is preferred, in accordance wi-th the invention, to apply the multi-phase mixture directly to the surface of the molten metal at several places.
Nitrogen is advantageously used as the liquid inert gas.
The invention will now be descrihed by reference to some embodiments and to the drawings illustrating them.
In the drawings:
Fig. 1 is a vertical section on line I-I of Fig 2 through a mould wherein the multi-phase mixture is supplied to the surface of the molten metal, Fig. 2 is a plan view of the Fig. 1 arrangement, and Fig. 3 is a section through part of an intermediate container having a casting tube and through part of a mould of a second embodiment.
Referrinq to Fig. 1, molten steel flows from an .-intermediate container, not illustrated, as an open poured stream 2 into a billet mould 1. In the zone of the casting head 3 the steel commences to solidify to form a crust 4, the thickness of whlch increases along the length of the strand. During casting, a multi-phase mixture is applied directly to thc surface 5 of the molten metal by way of a pipe 6, this mixture consisting of liquefied inert gas and, suspended therein, fusible solid bodies which are advantageously in the form of casting powder. A mixture of liquid inert gas with a little casting powder suspended therein and of unliquef.ied inert gas forms on thc surface 5 of the molten metal as a layer 7. Advantageously 1-15 kg of liquid inert gas, for example nitrogen, is supplied or each tonne o steelO The -suspended quantity of castiny powder is 0.01-0.2 kg in the above-mentioned quantity of gas. The liquid nitrogen is fed to a pipe 6 through a phase separator 30 as described in DT-OS
26 06 871. The casting powder is introduced into the pipe 6 with the aid of a low-pressure powder distributor 31, a consistent suspension being important. The multi-phase mixture to be applied to the surface 5 of the molten metal is regulated with the aid of a valve 32. Instead of casting powder, other fusible solid boclies capable of forming a suspension, for example glass powder, paraffin etc., can be added to the liquid inert gas. The outlet of the pipe 6 is located just above the surface of the molte~
metal and at a di~tance from the poured stream 2 that is greater than half the diameter of this stream in the zone of the surface of the molten metal. Advantageously, the multi-phase mixture is applied near the wall of the mould, say at a distan~e of 1 4 cm therefrom.
As shown in Fig. 2, the poured stream 2 has a diameter ~.
It should be mentioned that the poured stream 2 does not always have the ideal circular cross-section. When the poured stream 2 strikes the surface 5 of the molten metal, a wave 9 forms in the zone around the area of impact of the poured stream, the zone 10 terminating at a di~tance fxom the poured s~ream 2 that is approximately equal to half the diameter of said stream. This wave, caused by the kinetic energy of the poured stream, and the inert gas which vaporizes around the poured stream prevent the casting powder from reaching the~zone immediately adjacent the poured stream and from being carried into the molten casting head
This mixture of casting powder has a less efficient lubricating effect than liquefied casting powder, and this results in a strand surface of poorer quality and having pronou~lced osciLlation marks and casting powder inclusions. Oscillation marks promo-te the formation of cracks and lead to increased scarfing losses.
In the case of stainless steels, casting powder inclusions lead to increased grinding losses.
It is also known to use a homogeneous multi-phase mixture when continuously casting a metal into a mould with the poured stream of metal open i.e~ uncovered. In this p~ocedure a particulate substance, for example particles of soot are introduced into a lique~ied inert gas and are intended to improve the lubricating effect along the wall o the mould. In this system, the multi-phase mixture is applicd to the poured stream of metal by what is known as a phase separator. By way o~ the poured stream of metal, i.e. along this s~ream, the multi-phase mixture reaches the surface of the molten metal in the mould and protects the metal against the action of the atmosphere. Because of the introduction of the multi-phase mixture into the mould by way of the poured stream of metal and particularly when fairly large quantities of particulate substance are used, the particles are carried into the casting head by this poured stream of metal, and this leads to impurities. Also, when using this procedure for applying the multi-phase mixture to the poured stream of metal, trouble can occur due to ex~ernal influences, such as for example draught. The solid particles of the multi-phase mixture block the relatively small openings in the nozzles o~ the phase separator so that the protective effect of tle poured stream is unsatisfactory and this has a disadvantageous effect on the quality of the cast material. In the case of larger sizes of product, even distribution of the multi-phase mixture and there~ore of the solid bodies over the surface of the tnolten metal in the mould by way of the poured stream is not ensured, and this leads to uneven lubrication along the wall of the mould. Wavering of the poured stream following bottom-pouring cannot be prevented for various reasons, for example irregularities in the pouring nozzles~ This can result in the phase separator being sprayed with steel and this leads to trouble in supplying the multi-phase \
~9~
mixture and to stoppages in the castin~ operation.
The object of the present invention is to provide a method of applying a multi-phase mixture that, on the one hand, ensures trouble-free feed of the mixture, and, on the other hand, results in a high ~egree of purity of the cast steel and an improved surface.
This object is achieved in that during casting, the - multi-phase mixture of liquid inert gas containing a suspension of solid bodies, which fuse after separation from the mix-ture when in contact with the molten steel, is applied directly to the surface of the molten metal in the mould.
Surprisingly, it has been found that the application of the multi-phase mixture directly to the surface of the molten metal can largely prevent non-metallic particles fxom being carxied into the casting head. The solid bodies only perform the function of providing lubrication which is improved by the fusing of these solid bodies. The inclusion of solid bodies in the surface of the strand can be prevented. The multi-phase mixture takes over the function oE providing protection against atmospheric oxygen. Troubles at the feed apparatus due to spatter from the poured stream can no longer occur.
According to one feature of the invention, in casting with an open stream of poured rnetal the multi-phase mixture is applied at a distance ~rom the poured stream that is greater than half the diameter o this stream. When the poured stream strikes the surface of the molten metal in the mould a wave is formed in the zone around the poured stream, and the height and flow of this wave form a small protective wall which prevents the solid bodies from entering the zone in the i~nedaite vicinity of the poured stream and from being carried ~y this stream into the casting head. The open stream of poured material between the intermediate conkainer and the surface of the molten metal is - :
. . , . , ' . - . ' '. . . ' . , : ' . : ,, . . . : ': ' . ' protected against atmospheric oxygen b~ the vaporizing inert gas.
The impact of the poured stream on the surface of the molten metal eliminates a large part of t~le kinetic energy, so that the depth of flow in the sump is reduced an~ this has a favourabl~
effect upon the quality of the cast steel.
When casting larger sizes of product and using an open poured stream and the downwardly directed flow necessitated thereby, pronounced cooling of the steel in the zone of the surface of the molten metal in the mould cannot be prevented, and this leads to the formation of a top crust and therefore to considera~le reduction in quality in the cast strand~ According to the invention, this disadvantage is eliminated in that the steel emerging from the pouring orifice in the bottom of the intermediate vessel is introduced into the mould below the surface of the molten metal and is caused to flow towards and along said surface.
In acGordance with a further feature of the invention, a quantity of 1~15 kg of liquid inert gas and a quantity of 0.01-0.2 kg of casting powder are provided as the multi-phase miY~ture for each tonne of cast steel. The small quantity of casting powder has the effect of permitting only liquid casting powder to reach the zone between the wall of the mould and the steeL, and this results in a good lubricating action. The gas present in the zone of the wall of the mould prevents casting powder, contained in the liquid nitrogen, from reaching the wall of the mould so that the oscillatory movement does not cause any unfused casting powder to become mixed with the liquid casting powder, and this prevents the powder form ~eing included in the surface of the strand. Thus, losses due to dressing operations, such as for example grinding losses in the case of stainless steel, are reduced. The liquid casting powder performs the additional function of adsorbing non-metallic inclusions rising to the surface of the molten metal. When casting billets it is . .". : :
. . .
. ' . '' ,,', :"
~A~
possible to dispense with oil lubrication and this leads to elimination of the above-descri~ed disa~vantages particularly when casting lead-bearing free-cutting steels~
In order to achieve an even distribution of the multi phase mixture over the su.rface of the molten metal when producing products of larger size, it is preferred, in accordance wi-th the invention, to apply the multi-phase mixture directly to the surface of the molten metal at several places.
Nitrogen is advantageously used as the liquid inert gas.
The invention will now be descrihed by reference to some embodiments and to the drawings illustrating them.
In the drawings:
Fig. 1 is a vertical section on line I-I of Fig 2 through a mould wherein the multi-phase mixture is supplied to the surface of the molten metal, Fig. 2 is a plan view of the Fig. 1 arrangement, and Fig. 3 is a section through part of an intermediate container having a casting tube and through part of a mould of a second embodiment.
Referrinq to Fig. 1, molten steel flows from an .-intermediate container, not illustrated, as an open poured stream 2 into a billet mould 1. In the zone of the casting head 3 the steel commences to solidify to form a crust 4, the thickness of whlch increases along the length of the strand. During casting, a multi-phase mixture is applied directly to thc surface 5 of the molten metal by way of a pipe 6, this mixture consisting of liquefied inert gas and, suspended therein, fusible solid bodies which are advantageously in the form of casting powder. A mixture of liquid inert gas with a little casting powder suspended therein and of unliquef.ied inert gas forms on thc surface 5 of the molten metal as a layer 7. Advantageously 1-15 kg of liquid inert gas, for example nitrogen, is supplied or each tonne o steelO The -suspended quantity of castiny powder is 0.01-0.2 kg in the above-mentioned quantity of gas. The liquid nitrogen is fed to a pipe 6 through a phase separator 30 as described in DT-OS
26 06 871. The casting powder is introduced into the pipe 6 with the aid of a low-pressure powder distributor 31, a consistent suspension being important. The multi-phase mixture to be applied to the surface 5 of the molten metal is regulated with the aid of a valve 32. Instead of casting powder, other fusible solid boclies capable of forming a suspension, for example glass powder, paraffin etc., can be added to the liquid inert gas. The outlet of the pipe 6 is located just above the surface of the molte~
metal and at a di~tance from the poured stream 2 that is greater than half the diameter of this stream in the zone of the surface of the molten metal. Advantageously, the multi-phase mixture is applied near the wall of the mould, say at a distan~e of 1 4 cm therefrom.
As shown in Fig. 2, the poured stream 2 has a diameter ~.
It should be mentioned that the poured stream 2 does not always have the ideal circular cross-section. When the poured stream 2 strikes the surface 5 of the molten metal, a wave 9 forms in the zone around the area of impact of the poured stream, the zone 10 terminating at a di~tance fxom the poured s~ream 2 that is approximately equal to half the diameter of said stream. This wave, caused by the kinetic energy of the poured stream, and the inert gas which vaporizes around the poured stream prevent the casting powder from reaching the~zone immediately adjacent the poured stream and from being carried into the molten casting head
3 by this stream. As the liquid inert gas vaporizes, casting powder is deposited on the surface o~ the molten metal. As this is happening, the heat given off by the molten casting head causes the powder to fuse so that it can be drawn, as a film, into the space between the solidified crust 4 and the wall of the mould.
. .
, Since the unliquefied casting powder in the liquid nitrogen does not reach the walls of the mould because of the vaporization, the oscillatory movel~ent of the mould 1 cannot cause any unliquefied casting powder to find its way ~etween the steel and the wall of the mould. Thus it is possible, on the one hand, to maintain an optimum lubricating action with the small quantity of casting powder and, on the ~thcr hand, to prevent non-metallic particles from being carried into the casting head 3. Furth~rmore, the inert gas provides protection against atmospheric oxygen both for the surface of the molten metal and, i~ i~s gaseous form, for the poured stream issuing from the intermediate container.
Fig. 3 shows an intermediate container 15 having a bottom-pouring orifice 16. The steel issuing from the orifice 16 is carried below the surface S of the molten metal in a slab mould 20 by means of a casting pipe 17. The casting pipe 17 has two upwardly directed bores 21 drilled therein which impart to the steel a flow 22 which is directed towards and along the surface 5 of the molten metalO The liquid nitrog~n with the cas~ing powder suspended therein is applied directly on to the surface 5 of the molten metal through two pipes 6 and 6'. If required the layer 7 of the multi-phase mixture ca~ be applied at ad~itional places.
As a result of the flow 22 hot steel is always supplied to the surface of the molten metal so that a top crust cannot form~ while at the same time non-metallic inclusions can settle in the liquid layer of slag lying on ~he surface of the molten metal.
. .
, Since the unliquefied casting powder in the liquid nitrogen does not reach the walls of the mould because of the vaporization, the oscillatory movel~ent of the mould 1 cannot cause any unliquefied casting powder to find its way ~etween the steel and the wall of the mould. Thus it is possible, on the one hand, to maintain an optimum lubricating action with the small quantity of casting powder and, on the ~thcr hand, to prevent non-metallic particles from being carried into the casting head 3. Furth~rmore, the inert gas provides protection against atmospheric oxygen both for the surface of the molten metal and, i~ i~s gaseous form, for the poured stream issuing from the intermediate container.
Fig. 3 shows an intermediate container 15 having a bottom-pouring orifice 16. The steel issuing from the orifice 16 is carried below the surface S of the molten metal in a slab mould 20 by means of a casting pipe 17. The casting pipe 17 has two upwardly directed bores 21 drilled therein which impart to the steel a flow 22 which is directed towards and along the surface 5 of the molten metalO The liquid nitrog~n with the cas~ing powder suspended therein is applied directly on to the surface 5 of the molten metal through two pipes 6 and 6'. If required the layer 7 of the multi-phase mixture ca~ be applied at ad~itional places.
As a result of the flow 22 hot steel is always supplied to the surface of the molten metal so that a top crust cannot form~ while at the same time non-metallic inclusions can settle in the liquid layer of slag lying on ~he surface of the molten metal.
Claims (6)
1. A process for the continuous casting of steel and employing an intermediate container with bottom-pouring means and a pass-mould, the surface of the molten metal in the mould being covered by a multi-phase mixture of liquid inert gas and a particulate substance, characterized in that, during casting, the multi-phase mixture of liquid inert gas containing a suspension of solid bodies, which fuse after separation from the mixture when in contact with the molten steel, is applied directly to the surface of the molten metal in the mould.
2. A process according to Claim 1, characterized in that when casting with an open poured stream, the multi-phase mixture is applied at a distance from the poured stream that is greater than half the diameter of said stream.
3. A process according to Claim 1, characterized in that the steel issuing from the bottom-pouring orifice of the intermediate container is supplied below the surface of the molten metal in the mould and is caused to flow towards and along said surface.
4. A process according to Claim 1, 2 or 3, characterized in that the multi-phase mixture that is supplied consists of a quantity of 1-15 kg of liquid inert gas and a quantity of 0.01-0.2 kg of casting powder per tonne of cast steel.
5. A process according to Claim 1, 2 or 3, characterized in that the multi-phase mixture is applied directly to the surface of the molten metal at several places.
6. A process according to Claim 1, 2 or 3, characterized in that nitrogen is used as the liquid inert gas.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH16380/76 | 1976-12-28 | ||
| CH1638076A CH609263A5 (en) | 1976-12-28 | 1976-12-28 | Method for the continuous casting of steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1099891A true CA1099891A (en) | 1981-04-28 |
Family
ID=4416854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA293,848A Expired CA1099891A (en) | 1976-12-28 | 1977-12-23 | Process for the continuous casting of steel |
Country Status (14)
| Country | Link |
|---|---|
| JP (1) | JPS5384826A (en) |
| BE (1) | BE862396A (en) |
| BR (1) | BR7708668A (en) |
| CA (1) | CA1099891A (en) |
| CH (1) | CH609263A5 (en) |
| DE (1) | DE2758103A1 (en) |
| ES (1) | ES466021A1 (en) |
| FI (1) | FI61138C (en) |
| FR (1) | FR2375934A1 (en) |
| GB (1) | GB1585189A (en) |
| IN (1) | IN148728B (en) |
| IT (1) | IT1089234B (en) |
| SE (1) | SE7714350L (en) |
| YU (1) | YU306477A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2530167A1 (en) * | 1982-07-13 | 1984-01-20 | Air Liquide | Method and installation for protecting a liquid metal runner. |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2118867B1 (en) * | 1970-12-24 | 1974-02-15 | Etudes De Centrifugation | |
| FR2137090B1 (en) * | 1971-05-13 | 1973-12-28 | Air Liquide | |
| BE794855A (en) * | 1972-02-03 | 1973-05-29 | Voest Ag | REFRACTORY PIPE FOR CASTING MOLTEN METALS |
| FR2277144A1 (en) * | 1974-07-05 | 1976-01-30 | Air Liquide | COMPOSITION OF MATERIALS FORMED BY A MIXTURE OF A CRYOGENIC FLUID AND SOLID PARTICLES |
-
1976
- 1976-12-28 CH CH1638076A patent/CH609263A5/en not_active IP Right Cessation
-
1977
- 1977-12-16 SE SE7714350A patent/SE7714350L/en not_active Application Discontinuation
- 1977-12-23 YU YU03064/77A patent/YU306477A/en unknown
- 1977-12-23 CA CA293,848A patent/CA1099891A/en not_active Expired
- 1977-12-23 GB GB53729/77A patent/GB1585189A/en not_active Expired
- 1977-12-24 DE DE19772758103 patent/DE2758103A1/en active Pending
- 1977-12-24 IN IN1768/CAL/77A patent/IN148728B/en unknown
- 1977-12-26 FR FR7739225A patent/FR2375934A1/en not_active Withdrawn
- 1977-12-27 FI FI773932A patent/FI61138C/en not_active IP Right Cessation
- 1977-12-27 BR BR7708668A patent/BR7708668A/en unknown
- 1977-12-27 IT IT31290/77A patent/IT1089234B/en active
- 1977-12-28 ES ES466021A patent/ES466021A1/en not_active Expired
- 1977-12-28 BE BE183900A patent/BE862396A/en unknown
- 1977-12-28 JP JP15757977A patent/JPS5384826A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ES466021A1 (en) | 1978-10-01 |
| IN148728B (en) | 1981-05-23 |
| CH609263A5 (en) | 1979-02-28 |
| FR2375934A1 (en) | 1978-07-28 |
| FI773932A (en) | 1978-06-29 |
| FI61138C (en) | 1982-06-10 |
| FI61138B (en) | 1982-02-26 |
| DE2758103A1 (en) | 1978-07-13 |
| BR7708668A (en) | 1978-08-01 |
| GB1585189A (en) | 1981-02-25 |
| YU306477A (en) | 1982-10-31 |
| SE7714350L (en) | 1978-06-29 |
| BE862396A (en) | 1978-04-14 |
| JPS5384826A (en) | 1978-07-26 |
| IT1089234B (en) | 1985-06-18 |
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| MKEX | Expiry |