KR101446993B1 - Low surface roughness cast strip and method and apparatus for making the same - Google Patents

Abstract

The present invention relates to a thin strip casting strip comprising at least one microstructure selected from the group consisting of polygonal ferrite, spiny ferrite, Widmanstatten, bainite and martensite, And has a surface roughness of 1.5 microns Ra or less and a scale thickness of 10 microns or less. The strip according to the invention is obtained by applying a mixture of water and oil on a working roll of a hot rolling mill and applying the mixture of water and oil to the working roll while passing the strip casting strip through a hot rolling mill And shoveling the sheet metal strip from the casting rolls through a hot rolling mill.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast strip having a low surface roughness and a method and an apparatus for manufacturing the cast strip.

The present invention relates to a cast strip by a twin roll caster and a method and apparatus for manufacturing such a cast strip.

In a twin roll caster, a molten metal is introduced between a pair of horizontal casting rolls rotating in mutually opposite directions, the molten metal is cooled to solidify the metal shell on the moving roll surface, and the nip nip) to produce a solidified strip product that is transported down from the nip between casting rolls.

Here, the term "nip " means the entire region where the rolls are closest to each other. Molten metal is poured from a ladle through a metal supply system consisting of a turndish and a core nozzle located above the nip and is supported on the casting surface of the roll immediately above the nip, Thereby forming a molten metal casting pool extending along the longitudinal direction. These casting pools are usually confined between the end surfaces of the rolls and the side plates or side dams of the slide-bound refractory to prevent both ends from overflowing the casting pool.

When casting a steel strip in a twin roll caster, the strip exits the nip at a very high temperature, approximately 1400 ° C or higher. When exposed to an ordinary atmosphere, there is a problem that a scale is rapidly formed due to oxidation at a high temperature. Thus, a sealed enclosure through which the hot strip enters and from which the strip passes is provided underneath the casting roll, which encloses air to inhibit oxidation of the strip. The oxidation-inhibiting air may be formed by injecting a non-oxidizing gas, for example an inert gas such as argon or nitrogen, or a combustion exhaust gas which reduces the gas. Alternatively, the sealing device may be sealed to prevent the inflow of oxygen-containing air during operation of the strip casting machine. As disclosed in U.S. Patent Nos. 5,762,126 and 5,960,855, the oxygen content of the air in the enclosure is reduced at the early stage of the casting process by allowing oxidation of the strip and extracting oxygen from the sealed enclosure.

In order to form a thin strip, it is known to hot-roll the cast strip produced by the twin roll casting machine in a hot rolling mill after the strip exits the casting machine. It is generally known that the combination of a rolling mill and a twin roll casting machine is required to form a strip having a desirable cross-sectional profile.

However, hot-rolled strips cast in a hot-rolling mill cast with a standard casting speed of 80 m / min and then stripped by a hot-roll mill of 16% were found to have a micro-cracking of 6-8 microns ) Ra. ≪ / RTI > Figure 1 is a micrograph showing typical surface roughness of a cast and hot rolled strip exiting from a hot rolling mill arranged in line with a twin roll casting machine. Microphotographically, when rotated from left to right, lapping (20 to 30 um depth) is noticeable on the surface of the strip. The cause of such surface roughness may be shearing at the surface of the strip caused by sticking the strip to the surface of the work roll, imprinting of the work roll on the strip surface and / or other factors. In addition, micro-cracking of the surface of the cast strip is a problem. It is possible to reduce microcracks by reducing the casting speed and heat rate of the strip, but it is uneconomical to reduce these conditions during the manufacturing process.

The microstructure of hot strip mill products is essentially 100% equiaxed ferrite. However, when a cast strip is manufactured using a twin roll casting machine, conventionally, the microstructure is formed by coarse grains such as polygonal ferrite, acicular ferrite and coarse grains, Widmanstatten, ). Such microstructures are typically 30-60% polygonal ferrite, 40-70% bit mantle steel and acicular ferrite. In this microstructure, typical surface roughness is 4 to 7 microns Ra.

An object of the present invention is to provide a thin sheet cast strip having a low surface roughness and a method of manufacturing the same, in order to solve the above problems.

The present invention relates to a microstructure comprising at least one microstructure selected from the group consisting of polygonal ferrite, spiny ferrite, Widmanstatten, bainite and martensite, having a mean surface roughness (Ra) of 1.5 microns ) Or less and a scale thickness of 10 microns or less,

(a) a twin roll casting machine arranged side by side to form a nip therebetween, and a hot rolling mill adjacent to the twin roll casting machine and having work rolls and back-up rolls, ;

(b) forming a thin strip casting strip from the nip between casting rolls of the twin roll casting machine;

(c) applying a mixture of water and oil onto a working roll of the hot rolling mill;

(d) passing the strip cast strip through the hot rolling mill at a temperature of less than or equal to 1100 占 폚 while applying the mixture of water and oil to the work roll; And

(e) shrouding the thin strip casting strip from the casting rolls through the hot rolling mill in an oxygen atmosphere of up to 5% by volume on a volumetric basis: polygonal ferrite, spiny ferrite, Widmanstatten, bainite bainite, and martensite, and forming a thin strip casting strip having a surface roughness of 1.5 microns Ra or less and a scale thickness of 10 microns or less To provide a thin strip casting strip.

In addition,

(a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;

(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;

(c) assembling a hot rolling mill having a work roll having a work surface to form a gap therebetween, the hot rolling mill being adjacent to the strip casting machine;

(d) assembling spray nozzles adjacent to the work roll to provide a mixture of water and oil to the work roll;

(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the first side dam;

(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;

(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And

(h) rolling the cast strip between work rolls of the hot rolling mill to produce a cast strip having a surface roughness of less than 1 micron Ra, the surface roughness being reduced to less than 1.5 microns Ra Lt; RTI ID = 0.0 > strip < / RTI > strip.

In addition,

(a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;

(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;

(c) assembling a hot rolling mill adjacent to the strip casting machine, the hot rolling mill having a work roll having a backup roll and a work surface forming a gap therebetween, the hot strip being rolled;

(d) assembling a spray nozzle disposed on top of the work roll to provide a mixture of water and oil to the backup roll;

(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the first side dam;

(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;

(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And

(h) rolling the cast strip between working rolls of the hot rolling mill to produce a cast strip having a surface roughness of less than 1.5 microns Ra

, Wherein the surface roughness is reduced to 1.5 microns Ra or less.

The thin strip cast strip has a surface roughness of less than or equal to 1.0 micron Ra or less than or equal to 0.7 micron Ra or less than or equal to 0.5 micron Ra.

The strip cast strip has a scale thickness of less than or equal to 7 microns.

The thin strip casting strip is characterized in that it passes through the hot rolling mill at a temperature of 1050 DEG C or less while the mixture of oil and water is applied to the working roll.

The strip cast strip has a scale thickness of less than or equal to 7 microns.

The mixture of oil and water is applied to the working roll by spraying.

The mixture of oil and water is applied to the backup roll.

The mixture of oil and water contains up to 5% oil to form a thin sheet cast strip having a low surface roughness of less than 1.5 microns Ra.

The present invention also relates to a ferrite material comprising at least one microstructure selected from the group consisting of polygonal ferrite, needle-like ferrite, bitman stenter, bainite and martensite, having a surface roughness of 1.5 microns Ra or less and a scale thickness of 10 microns or less A method of making a strip cast strip, the method comprising:

(a) assembling a twin-roll casting machine arranged side by side to form a nip therebetween and a hot rolling mill adjacent to the twin roll casting machine and having work rolls and back-up rolls;

(b) forming a thin strip casting strip from the nip between casting rolls of the twin roll casting machine;

(c) applying a mixture of water and oil on a working roll of the hot rolling mill;

(d) passing the strip cast strip through the hot rolling mill at a temperature of less than or equal to 1100 占 폚 while applying the mixture of water and oil to the work roll; And

(e) shrouding the thin strip casting strip from the casting rolls through the hot rolling mill in an oxygen atmosphere of up to 5% by volume on a volumetric basis: polygonal ferrite, spiny ferrite, Widmanstatten, bainite bainite and martensite and has a surface roughness of 1.5 microns Ra (average surface roughness) or less and a scale thickness of 10 microns or less And forming a thin strip casting strip.

In addition,

(a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;

(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;

(c) assembling a hot rolling mill having a work roll having a work surface to form a gap therebetween, the hot rolling mill being adjacent to the strip casting machine;

(d) assembling a spray nozzle adjacent to the work roll so as to provide a mixture of water and oil to the work roll;

(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the first side dam;

(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;

(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And

(h) rolling the cast strip between work rolls of the hot rolling mill to produce a cast strip having a surface roughness of less than 1 micron Ra, wherein the cast strip has a reduced surface roughness of less than 1.5 microns Ra A method of manufacturing a thin strip steel strip is provided.

In addition,

(a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;

(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;

(c) assembling a hot rolling mill adjacent to the strip casting machine, the hot rolling mill having a work roll having a backup roll and a work surface forming a gap therebetween, the hot strip being rolled;

(d) assembling a spray nozzle disposed upstream of the work roll to provide a mixture of water and oil to the backup roll;

(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the first side dam;

(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;

(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And

(h) rolling the cast strip between working rolls of the hot rolling mill to produce a cast strip having a surface roughness of less than 1.5 microns Ra

And a reduced surface roughness of less than or equal to 1.5 microns Ra.

The method includes spraying a mixture of oil and water onto the work roll with a spray nozzle, for example.

The spraying rate by the nozzle is 10 to 30 gpm (gallons per minute).

A mixture of the oil and water is applied to the work roll by applying a mixture of the oil and water to the backup roll.

The process produces a cast strip at a rate of 80 m / min.

And the rolling temperature is 1100 DEG C or less or 1050 DEG C or less or 900 DEG C or less.

As described above, the sheet steel cast strip according to the present invention, prepared by adding the oil-water mixture, has the effect of having a significantly lower average surface roughness of about 0.66 to about 1.5 microns.

1 is a micrograph showing a typical surface roughness of a cast strip after hot rolling,
Figure 2 schematically shows a thin strip casting machine with a hot rolling mill controlling the shape of the cast strip,
3 is an enlarged side view of the casting machine of the thin strip strip casting apparatus shown in Fig. 2,
Figure 4 schematically shows a system for applying a mixture of oil and water to a roll of a hot rolling mill,
Fig. 5 is a diagram showing an average surface roughness of a sheet steel cast strip 2613 produced by the present invention. Fig.

Hereinafter, the operation of the embodiment of the twin roll casting apparatus according to the present invention will be described with reference to the accompanying drawings.

The illustrated casting and rolling apparatus generally comprises a twin roll caster denoted by the reference numeral 11 which comprises a guide table guide from a transient path to a pinch roll stand 14, to produce a cast steel strip (12) that passes across a table (13). After passing through the pinch roll stand 16, the thin strip casting strip 12 passes through a hot rolling mill 15 composed of a backup-roll 16 and upper and lower work rolls 16A and 16B, And its thickness decreases. The strip 12 exits the mill 15 and proceeds to a run out table 17 where cooling can be facilitated by water jets 18 on the process table 17 And then passes through a pinch roll stand 20 constituted by a pair of pinch rolls 20A to the coiler 19.

The twin roll casting machine 11 includes a main machine frame which supports a pair of casting rolls 22 arranged side by side with a casting surface 22A forming a nip therebetween. The molten metal is fed from a ladle (not shown) through a refractory shroud to a distributor vessel or a transition piece during the casting process and then fed through a metal feed nozzle (also called a core nozzle) And is supplied onto the nip between the calf rolls 22.

Molten metal is introduced from the tundish 23 into the movable tundish 25 via the outlet of the refractory shroud. The tundish 23 is provided with a stopper rod and a slide gate valve (not shown) for effectively controlling the flow of the molten metal from the tundish 25 to the casting machine by selectively opening or closing the discharge port of the shroud. Respectively. The molten metal flows from the movable tundish 25 through the outlet and selectively flows to the transfer nozzle 28 or through the transfer nozzle.

The molten metal is thus supplied to the casting roll 22 to form a casting pool just above the nip supported by the casting roll surface 22A. This casting pool is defined by a pair of side dams or side plates at the ends of the roll and is connected to a pair of stirrers including a hydraulic cylinder unit connected to the side dam thrusters (not shown) at the end of the roll. The upper surface of the casting pool (commonly referred to as the "meniscus" level) rises above the lower end of the transfer nozzle 28, And the lower end is immersed in the casting pool.

The casting roll 22 is internally cooled by supplying a coolant (not shown), and is driven to rotate in opposite directions by a driving device (not shown) so that the shell solidifies on the moving casting roll surface, To produce a thin strip casting strip 12 which is fed downward from the nip between the casting rolls.

At the bottom of the twin roll casting machine 11 the cast steel strip 12 passes through a guide table 13 in a sealed enclosure 10 and the guide table 13 moves the strip to a pinch roll stand (14), and the strip passes through the pinch roll stand (14) and exits the sealed sealing device (10). Although sealing of the enclosure 10 may not be perfect, it is appropriate to control the air in the enclosure and to control oxygen access to the cast strip in the enclosure as described below. After exiting the sealed enclosure 10, the strip may pass through a further sealed enclosure that is located at the rear end of the pinch roll stand 14 and includes a hot rolling mill 15.

The enclosure 10 comprises a plurality of separate wall sections which are joined together at various sealing connections forming a continuous enclosure wall. These separating wall portions include a first wall portion 41 formed to surround the casting roll 22 in a twin roll casting machine and an opening sealed to the upper edges of the scrap box receptacle 40 (42) extending downwardly from the bottom of the first wall portion (41) to form a second wall portion (41). The seal 43 between the scrap box container 40 and the wall enclosure 42 is formed by a knife and a sand seal around the opening of the enclosure wall 42, The seal may be broken or may be broken by the vertical movement of the scrap box container 40 relative to the scrap box container 40. The seal 43 is made by lifting the scrap box container 40 and penetrating and sealing the knife flange into the sand in the groove.

The seal 43 can be broken by lowering the scrap box container 40 from the operating position before moving from the casting machine to the scrap discharge position (not shown). The scrap box container 40 can be moved to the scrap discharge position by placing the scrap box container 40 on the carriage 45 on which the wheels 46 running on the rail 47 are mounted. The conveyor 45 can be used as long as the scrap box container 40 can be lifted to a lowered position, that is, a position where the knife flange is inserted into the sand from a position spaced from the sealing wall 42 to form a seal 43 And a set of powered screw jacks 51.

The sealed enclosure 10 further includes a third wall portion 61 disposed around the guide table 13 and connected to the frame of the pinch roll stand 14 including a pair of pinch rolls 50 . The third wall portion 61 of the sealing device 10 is sealed by sliding seals.

Most of the sealing wall portions 41, 42, 61 may be lined with a refractory brick. The scrap box container 40 may also be lined with refractory bricks or castable refractory lining. In this way, sealing the sealing device 10 perfectly prior to the casting process allows the strip to move from the casting roll 22 to the pinch roll stand 14 and the hot rolling mill 15, ). Initially, the strip 12 forms a heavy scale on the beginning of the strip so that it can absorb all of the oxygen from the air inside the enclosure 10. However, the sealed enclosure 10 limits the oxygen inflow from the ambient air into the enclosure to be below the amount of oxygen that can be absorbed by the strip 12. Thus, after an initial start-up period, the oxygen contained in the air in the enclosure 10 will be in a depleted state, limiting the availability of oxygen for oxidizing the strip 12. In this way, the scale formation can be controlled to a thickness of 10 microns or less without continuously supplying a reducing gas or a non-oxidizing gas into the enclosure 10. Of course, reducing gas or non-oxidizing gas can be injected through the enclosure wall. However, in order to prevent a large scale from being formed during the operation start cycle, the sealing device 10 can be cleaned just before the beginning of the casting process to lower the initial oxygen level inside the sealing device 10, This can reduce the time period for stabilizing the oxygen level in the enclosure resulting from the interaction with oxygen in the oxidation of the strip passing through the enclosure. Therefore, as an embodiment, the enclosure 10 can be easily cleaned by, for example, nitrogen gas. Found that scaling of the strip at the outlet of the enclosure 10 is limited to 10 microns to 17 microns, even when the initial oxygen content is reduced to the level of 5% to 10%, even during the initial start-up. In one embodiment of the present invention, during continuous casting processes, the sheet steel strip has a scale thickness of about 10 microns or less, or 7 or 4 microns or less.

In the early stage of the casting process, as the casting conditions are stabilized, short strips of incomplete strips are produced. After continuous casting, the casting rolls 22 are moved to slightly spaced apart and then contacted again, which leads to the leading end of the strip in the manner described in Australian Patent No. 646,981 and U.S. Patent No. 5,287,912, So that the following thin sheet cast strips 12 form a clean head end. This incomplete material falls into the scrap box container 40 located below the casting machine 11 and is then shaken down from one side of the casting machine, usually from the pivot 39, A swinging apron 38 guides the clean end of the strip of strip casting 12 over the guide table 13 by wobbling across the outlet of the casting machine, And is supplied to the stand 14. The apron 38 is then returned to the hanging position as shown in FIG. 3, before the strip is moved over the guide table 13, as shown in FIGS. 2 and 3, loop (36). The guide table 13 consists of a series of strip support rolls 37 to support the strip before it moves to the pinch roll stand 14. The rolls 37 are arranged in an array so as to be deflected downwardly from the pinch roll stand 14 back to the bottom of the casting machine to smoothly receive and guide the strips from the loops 36.

The twin roll casting machine may employ the type shown and described in detail in U.S. Patent No. 5,184,668 and U.S. Patent No. 5,277,243 or U.S. Patent No. 5,488,988. References to these patents are for the sake of brevity and are not a part of the present invention.

The pinch roll stand 14 is provided with a pair of pinch rolls 50 indicating the reactance to the applied tension by the hot rolling mill 15. Thus, the strip can hang from the casting roll 22 into the loop 36 while moving into the guide table 13 and the pinch roll stand 41. Thus, the pinch roll 50 provides a tension barrier between the loosely engaged loop and the tension on the downstream of the strip in the process line. The pinch roll 50 also stabilizes the position of the strip on the feed table 13 which feeds the strip to the hot rolling mill 15.

The strip cast strips 12 are conveyed from the pinch rolls 14 to a hot rolling mill 15 comprising an upper work roll 16A and a lower roll 16B. As shown in Figure 4, a preferred embodiment of the present invention involves spraying a mixture of water and oil on the downstream surface of backup roll 16. The oil reservoir 100 has a heater 101 for maintaining the oil at about 50 캜, but does not need to be heated. The heated oil is transferred to static mixers 104 via a transfer line 103 mounted on a displacement pump 102 and the heated oil is mixed with water in a fixed mixer 104 do.

Water is supplied from a source 110 to a water strip chilling header 111 and a rolling roll feed line 112. The first portion of the water exits the hot rolling mill 15 and is then fed to the spray header 18 to supply cooling water for cooling the hot strips 12. Generally, the water pressure is regulated through the pressure regulator 113 to about 40 psi. Between about 10 and 30 gpm of water is supplied to each stationary mixer 104, where water is mixed with about 4 gph of heated oil.

The mixed oil and water is then passed through the oil-water supply nozzle 71 to downstream surfaces of the back-up roll 16 (the direction of movement of the strip steel strip 12 is indicated by arrow 120) . Alternatively, the oil-water mixture applied to the cast strip 12 within the area of the roll engagement can be applied to the upper surface of the backup roll 16 or to the work rolls 16A, 16B.

Preferably, the temperature of the strip steel strip 12 in the hot rolling mill 15 is less than or equal to 1100 占 폚, more preferably less than or equal to 1050 占 폚, and most preferably less than or equal to 900 占 폚. Preferably, the temperature of the thin strip steel strip 12 in the hot rolling mill 15 is 400 DEG C or higher.

The stationary mixer 104 is a conventional apparatus that can be used conventionally and other types of mixers capable of mixing oil and water well can be used.

In one embodiment, the oil-water mixture is fed to backup roll 16 at about 5 to 30 gpm under a pressure of 40 psi. In this embodiment, the oil-water mixture is supplied to the back-up roll 16 in an amount of about 10 to 20 gpm, and 15 gpm is a proper setting value. The oil-water mixture comprises up to 5% oil, and in one embodiment, by volume, comprises 4 parts of oil and 600 to 1800 parts of water. The oil is not more than 2% or 1% of the mixture. The oil is usually supplied to be mixed with less than 15 gph of water.

Figure 5 shows the Average Surface Roughness (Ra) of the sheet steel strip 12 produced using the present invention. As shown in FIG. 5, it can be seen that the average surface roughness is significantly lowered by adding the oil-water mixture as described above, from about 0.66 to about 1.5 microns.

In one embodiment, the present invention involves the production of sheet steel casting strips using the oil-water application described above to produce sheet steel strip at a speed of at least 80 meters per minute (80 meters per minute).

It should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention as defined by the appended claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. Accordingly, the invention is not to be considered as being limited to the particular embodiments disclosed, but is to be accorded the widest scope consistent with the appended claims.

Claims (28)

(Average surface roughness) of less than or equal to 1.5 microns Ra (average surface roughness), at least one microstructure selected from the group consisting of polygonal ferrite, polyhedral ferrite, needle-like ferrite, Widmanstatten, bainite and martensite. A thin sheet cast strip having surface roughness and a scale thickness of less than 10 microns,
(a) a twin roll casting machine arranged side by side to form a nip therebetween, and a hot rolling mill adjacent to the twin roll casting machine and having work rolls and back-up rolls, ;
(b) forming a thin strip casting strip from the nip between casting rolls of the twin roll casting machine;
(c) applying a mixture of water and oil onto a working roll of the hot rolling mill;
(d) applying the mixture of water and oil to the working roll while passing the strip casting strip through the hot rolling mill at a temperature of 1100 占 폚 or lower; And
(e) shoveling the thin strip casting strip from the casting rolls through the hot rolling mill in an oxygen atmosphere of 5% or less by volume on a volumetric basis: polygonal ferrite, spun ferrite, bitumentite, bainite and martensite A process for forming a thin strip casting strip comprising at least one microstructure selected from the group consisting of and having a surface roughness of less than 1.5 microns Ra and a scale thickness of less than 10 microns
≪ / RTI > characterized in that the strip is produced by the process comprising the steps of: 2. The strip casting strip according to claim 1, wherein the thin strip casting strip passes through the hot rolling mill at a temperature of 1050 DEG C or less while the mixture of oil and water is applied to the working roll. The thin strip casting strip according to claim 1, wherein the surface roughness is 1.0 micron Ra or less. 4. The strip casting strip according to claim 3, wherein the surface roughness is 0.7 micron Ra or less. 5. The strip casting strip according to claim 4, wherein the surface roughness is 0.5 micron Ra or less. The strip casting strip of claim 1, wherein the scale thickness is less than or equal to 7 microns. 7. The strip casting strip of claim 6, wherein the scale thickness is less than or equal to 4 microns. 8. A strip casting strip according to any one of claims 1 to 7, characterized in that said oil and water mixture is applied by said working roll spraying. 8. A strip casting strip according to any one of claims 1 to 7, wherein said mixture of oil and water is applied to said work roll by applying said oil and water mixture to said backup roll. The strip of claim 1, wherein the mixture of oil and water is less than 5% oil. A thin sheet cast strip having a surface roughness reduced to less than or equal to 1.5 microns Ra,
(a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;
(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;
(c) assembling a hot rolling mill having a work roll having a work surface to form a gap therebetween, the hot rolling mill being adjacent to the strip casting machine;
(d) assembling spray nozzles adjacent to the work roll to provide a mixture of water and oil to the work roll;
(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the side dam;
(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;
(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And
(h) rolling the cast strip between work rolls of the hot rolling mill to produce a cast strip having a surface roughness of less than or equal to 1.5 microns Ra. Having thin strip casting strips. 12. The method of claim 11,
Wherein the production rate of the cast strip is at least 80 m / min. 13. A strip casting strip as claimed in claim 11 or 12, characterized in that the rolling temperature is 900 DEG C or less. 12. A strip casting strip as claimed in claim 11, characterized in that the spraying rate by the spray nozzle is between 10 and 30 gpm. 12. The strip casting strip as claimed in claim 11, wherein the surface roughness is less than or equal to 0.7 microns Ra. 16. The strip casting strip of claim 15, wherein the surface roughness is less than 0.4 micron Ra. A thin sheet cast strip having a surface roughness reduced to less than or equal to 1.5 microns Ra,
(a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;
(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;
(c) assembling a hot rolling mill adjacent to the strip casting machine, the hot rolling mill having a work roll having a backup roll and a work surface forming a gap therebetween, the hot strip being rolled;
(d) assembling a spray nozzle disposed on top of the work roll to provide a mixture of water and oil to the backup roll;
(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the side dam;
(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;
(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And
(h) rolling the cast strip between working rolls of the hot rolling mill to produce a cast strip having a surface roughness of less than 1.5 microns Ra
Wherein the surface roughness is reduced to 1.5 microns Ra or less. 18. The method of claim 17,
Wherein the production rate of the cast strip is at least 80 m / min. The surface roughness is reduced to 1.5 microns Ra or less. 18. The strip casting strip of claim 17, wherein the rolling temperature is less than or equal to 1100 < 0 > C, wherein the surface roughness is reduced to less than 1.5 microns Ra. The thin strip casting strip according to claim 19, wherein the rolling temperature is 1050 占 폚 or less, wherein the surface roughness is reduced to 1.5 microns Ra or less. The thin strip casting strip according to claim 20, wherein the rolling temperature is 900 캜 or less, wherein the surface roughness is reduced to 1.5 microns Ra or less. 18. The strip casting strip as claimed in claim 17, wherein the spraying speed by the atomizing nozzle is 10 to 30 gpm, wherein the surface roughness is reduced to 1.5 microns Ra or less. 18. The strip casting strip as claimed in claim 17, wherein the surface roughness is less than or equal to 0.7 microns Ra. 24. Laminate strip according to any one of claims 17 to 23, characterized in that the oil and water mixture has an oil content of 5% or less, wherein the surface roughness is reduced to 1.5 microns Ra or less. 24. A strip casting strip as claimed in any one of claims 17 to 23, wherein the sheet steel cast strip has a surface scale thickness of less than or equal to 7 microns. A thin sheet cast strip having at least one microstructure selected from the group consisting of polygonal ferrite, acicular ferrite, bitman stenter, bainite and martensite and having a surface roughness of 1.5 microns Ra or less and a scale thickness of 10 microns or less, A method of making, the method comprising:
(a) assembling a twin-roll casting machine arranged side by side to form a nip therebetween and a hot rolling mill adjacent to the twin roll casting machine and having work rolls and back-up rolls;
(b) forming a thin strip casting strip from the nip between casting rolls of the twin roll casting machine;
(c) applying a mixture of water and oil on a working roll of the hot rolling mill;
(d) passing the strip cast strip through the hot rolling mill at a temperature of less than or equal to 1100 占 폚 while applying the mixture of water and oil to the work roll; And
(e) shrouding the thin strip casting strip from the casting rolls through the hot rolling mill in an oxygen atmosphere of 5% or less by volume on a volumetric basis: polygonal ferrite, spiny ferrite, bitumentite, bainite and martensite Forming a thin sheet cast strip having at least one microstructure selected from the group consisting of, and having a surface roughness of 1.5 microns Ra or less and a scale thickness of 10 microns or less. (a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;
(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;
(c) assembling a hot rolling mill having a work roll having a work surface to form a gap therebetween, the hot rolling mill being adjacent to the strip casting machine;
(d) assembling a spray nozzle adjacent to the work roll so as to provide a mixture of water and oil to the work roll;
(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the side dam;
(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;
(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And
(h) rolling the cast steel strip between work rolls of the hot rolling mill to produce a cast steel strip having a surface roughness of less than or equal to 1.5 microns Ra. A method of manufacturing a thin strip steel strip having surface roughness. (a) assembling a strip casting machine having a pair of casting rolls having a nip therebetween;
(b) assembling a metal supply system capable of forming the casting pool on the nip between the casting rolls, the side dams being adjacent to the end of the nip for defining a casting pool;
(c) assembling a hot rolling mill adjacent to the strip casting machine, the hot rolling mill having a work roll having a backup roll and a work surface forming a gap therebetween, the hot strip being rolled;
(d) assembling a spray nozzle disposed on top of the work roll to provide a mixture of water and oil to the backup roll;
(e) introducing molten metal between the pair of casting rolls to form a casting pool supported on the casting surface of the casting roll defined by the side dam;
(f) a step of rotating the casting rolls in opposite directions to solidify the metal shell on the casting surface of the casting roll, and forming a cast steel strip through the nip between the casting rolls from the coagulated shell ;
(g) spraying a mixture of oil and water when the strip enters the hot rolling mill; And
(h) rolling the cast strip between working rolls of the hot rolling mill to produce a cast strip having a surface roughness of less than 1.5 microns Ra
Wherein the surface roughness is less than 1.5 microns Ra. ≪ RTI ID = 0.0 > 11. < / RTI >

Images