KR102372586B1 - Impact pad, tundish and apparatus including the impact pad, and method of using same - Google Patents

Abstract

A tundish shock pad, a tundish including the same, and a method of using the shock pad and tundish, and an assembly including the same are provided. The tundish impact pad has a base having a base surface having a conical impact surface area defining an apex, a sidewall, and an inner end spaced over and centered over the apex to terminate at an inner end relative to the sidewall. It is characterized in that it comprises an upper wall extending to. The top wall includes a lip that slopes radially, inwardly and downwardly towards the conical impact surface.

Description

Shock pad, tundish and device including shock pad, and method of using the same

This application claims priority to U.S. Provisional Patent Application No. 62/037,949, filed on August 15, 2014. The present invention relates to a shock pad used in steel making, and more particularly, to a tundish shock pad suitable for reducing turbulence and rough surface collapse caused by a ladle stream of molten steel fed into a continuous casting machine tundish. it's about The present invention also relates to a tundish and device comprising the shock pad, and to methods of using the shock pad, tundish, and device.

A steel casting machine is an apparatus for performing continuous casting, and is referred to as continuous casting in the prior art. Continuous casting involves transferring molten steel from a steelmaking furnace to a ladle. This molten steel is fed into the vessel through a ladle shroud that extends from the ladle into a vessel called a tundish. Typically, this tundish serves as a silo that allows molten steel to be fed from the silo to the casting machine mold, without interruptions or undesired stagnation times. In order to protect the molten steel in the tundish from unwanted chemical reactions, ie peroxidation and airborne particles, a protective slag cover/layer or “flux” is allowed on the surface of the molten steel bath.

The surface requirements and cleanliness standards of modern high-quality steel products allow for very low tolerances of impurities and chemical changes. These impurities and chemical changes are often the result of turbulence caused by the incoming ladle flow of molten steel fed to the tundish. The tundish design for receiving liquid steel from the ladle shroud leads to undesirable fluid flow conditions such as turbulence inside the tundish and promotes high free surface flow activity. For example, the fluid flow generated by the incoming ladle flow can be reflected from the flat tundish bottom and sidewalls towards the surface of the liquid river. This generated fluid flow causes a turbulent boiling action, a wide range of undulations, and rubbing against the surface of the steel bath.

For example, FIG. 10 shows a longitudinal cross-sectional view of a single strand tundish having an asymmetric fluid flow 9a. A ladle shroud 7 is shown adjacent to an end wall 3 acting as a well block (not shown in FIGS. 10 and 11 ). Through a water flow-model study, it was found that the fluid flow, caused by the incoming ladle flow (8) from the ladle shroud (7), was reflected upwardly from the flat tundish bottom (4) towards the surface of the liquid river. could If this fluid flow is restricted by tundish walls 2 and 3 , this restricted fluid flow is forced upward along the surface of those walls 2 and 3 . This upward flow flows into the circular passage 9c and generates an upward surge along the surface of the end wall 3 and a downward flow around the periphery of the ladle shroud 7 . The upward rise of circular flow 9C creates excessive turbulence at the surface of the bath. This high free surface activity in the tundish causes a phenomenon called "open-eye", which breaks the protective slag cover 6 on top of the steel bath. Broken slag cover 6 exposes the molten steel to the ambient atmosphere, changes the chemistry of the steel bath, and establishes conductive conditions for creating inclusions in the steel bath. Chemical changes generally involve the loss of aluminum from the steel bath and/or absorption of oxygen and nitrogen into the steel bath and the resulting re-oxidation. Reoxidation and other undesirable reactions, for example, can inject excess alumina, manganese sulfide, calcium sulfide into the steel bath. Also, the downward flow around the ladle shroud 7 creates shear and vortices, trapping the broken particles in the broken flux shroud 6 and dragging them down into the liquid bath. These broken particles 10 are eventually discharged from the molten steel and tundish and create inclusions in the finished steel product.

Chemical changes and inclusions ultimately degrade steel quality and are a major cause of rejection of expensive steel grades such as HIC and armor plate grades. Also, splashing of hot molten steel on the walls of the tundish can represent a safety hazard to the operator. Using conventional equipment, the lack of homogeneity of the steel bath temperature and the insufficient residence time for inclusion particles to float to the protective slag cover may lead to problems that the particles may be sequestered and/or separated from the molten steel.

Various attempts have been made to reduce or eliminate surface turbulence in continuous casting tundish to improve the quality of the finished product. These attempts have included various types of dams and weirs to divert ladle flow fluid flow at the surface of the molten steel bath. Although some known fluid flow control devices have been somewhat successful in controlling fluid flow and reducing surface turbulence, these control devices are insufficient to meet the demands of high quality steel as described above and tend to cause operational problems.

It is an object of the present invention to provide a shock pad, a tundish including the shock pad and a device, and a method of using the same.

According to a first aspect of the present invention, a base having a base surface having a conical impact surface area defining an apex, a side wall, and a side wall terminating at an inner end defining an inlet opening spaced above and centered thereon A tundish shock pad is provided that features a top wall extending inwardly with respect to the tundish. The top wall includes a lip that slopes radially, inwardly and downwardly towards the conical impact surface.

A second aspect of the present invention provides an apparatus comprising a continuous caster tundish comprising a reservoir of molten metal having a fluid flow created by an incoming ladle flow, and a tundish shock pad within the continuous caster tundish. do. The tundish impact pad extends inwardly relative to the sidewall to terminate at a base having a base surface comprising a conical impact surface area defining an apex, a sidewall, and an inner end defining a centrally located inlet opening spaced upwardly relative to the apex. and an upper wall that The top wall includes a rib that slopes radially, inwardly and downwardly towards the conical impact surface.

A third aspect of the present invention is the conical impact of the tundish impact pad before the incoming ladle stream of molten liquid steel is fed into the continuous caster tundish and allowed to flow into the tundish reservoir through the inlet opening of the tundish impact pad. A strand casting method or a molten steel treatment method for impinging on a surface area is provided. The tundish impact pad includes a base having a base surface, a side wall, and a top wall extending inwardly with respect to the side wall to terminate at an inner end defining an inlet opening spaced above and centered on the apex of the conical impact surface area. The top wall includes a rib that slopes radially inwardly and downwardly towards the conical impact surface.

According to an embodiment of each of the aspects described herein, the top wall of the tundish shock pad, together with the bottom surface and the continuous inner surface of the side wall, is configured to reduce turbulence of the incoming ladle flow of the molten liquid steel. It features a lower surface defining a continuous annular chamber.

According to another embodiment of the aforementioned aspects, the conical impact surface area has an axis through the vertex having rotational symmetry.

According to another embodiment of the aforementioned aspects, the conical impact surface area has a linear profile.

In accordance with yet another embodiment of the foregoing aspects, the conical impact surface area has a cone angle measured from a horizontal plane with a perimeter of the conical impact surface area to an inclined surface with a conical impact surface area in a range from about 15 degrees to about 25 degrees.

In accordance with another embodiment of the aforementioned aspects, the lip has a downward lip angle measured from a horizontal plane of the lip to a lower surface in a range of about 20 degrees to about 25 degrees.

In accordance with another embodiment of the aforementioned aspects, the continuous annular chamber has a radius of curvature of about 30 mm.

According to another embodiment of the aforementioned aspects, the protrusion, for example a hemispherical protrusion, is distributed around the area of the lower surface of the lip.

The above-described embodiments may be implemented in combination with each other.

Other aspects and embodiments of the present invention, including apparatus, assemblies, apparatus, articles, methods of manufacture and use, processes, etc., which form part of the present invention, will become more apparent upon reference to the detailed description of the following exemplary embodiments. .

As described above, the shock pad of the present invention, a tundish comprising the shock pad, and a method and apparatus using the same significantly reduce the problems of "open eye" and scattering. The effect of reducing turbulence due to high-speed inflow flow and magnetic braking effect, lengthening the residence time of the molten steel in the storage tank, promoting the flotation of impurities and particles, maintaining the storage temperature uniformly, and improving the cleanliness of the molten steel there is.

The accompanying drawings are incorporated in and constitute a part of this specification. The accompanying drawings, together with the foregoing general description and the following detailed description of exemplary embodiments and methods, serve to explain the principles of the invention. In these drawings:
1 is a front perspective view of an end surface of a single strand caster tundish including a shock pad according to an embodiment of the present invention;
Figure 2 is a front elevational view of the single strand casting machine tundish of Figure 1;
Fig. 3 is a front perspective view of the shock pad of the embodiment shown in Fig. 1;
Fig. 4 is a plan view of the shock pad of Fig. 3;
Fig. 5 is a cross-sectional view taken along line VV in Fig. 4;
Fig. 6 is a cut-away side perspective view of the shock pad of Figs.
Fig. 7 is an end cross-sectional view taken at the point of the right arrow in Figs. 1 and 2, showing the flow distribution of the incoming liquid river injected through the shroud centered over the shock pad;
8 is a cross-sectional view of a shock pad according to another embodiment of the present invention;
Fig. 9 is a bottom cross-sectional view taken along line IX-IX of Fig. 8;
10 and 11 are reproduced from US Patent No. 35,685, FIG. 10 is a longitudinal cross-sectional view showing a water flow model training tundish, and FIG. 11 is a cross-section taken along line XI-XI of FIG.

Reference will be made in detail to exemplary embodiments and methods as shown in the accompanying drawings, in which like reference numerals indicate like or corresponding parts throughout the drawings. However, in a broader view of the invention, it should be noted that the invention is not necessarily limited to the illustrative examples shown and described in connection with the specific details, representative materials and methods, exemplary embodiments and methods.

A tundish for a strand casting machine according to an exemplary embodiment is generally indicated by reference numeral 10 in FIGS. 1 and 2 . Although a single strand caster is shown therein, it should be understood that embodiments of the present invention may be practiced in connection with double or other multiple strand casters. An example of a multi-strand caster installation despite having different shock pads is shown in FIG. 10 of US Patent No. RE 35,685. The tundish 10 includes tundish endwalls 12 and 14, tundish front and rear sidewalls (not shown), and extending between and connected to (or integrated with) the endwalls 12 and 14 and the sidewalls. Includes a tundish floor (16). The tundish end walls 12 , 14 and the bottom 16 jointly form a chamber or reservoir 18 for containing and holding the molten steel. The tundish shock pad 20 is positioned in the reservoir 18 closer to the end wall 12 than, for example, the end wall 14 . The lower portion of the ladle shroud 22 for injecting the inflow ladle stream 24 (FIG. 7) of molten steel into the shock pad 20 is positioned above the tundish shock pad 20. The ladle shroud 22 is shown passing through the upper part of the molten steel bath, and the end of the ladle shroud 22 is spaced concentrically upward from the tundish shock pad 20 and is located in the center. The structure and function of the flow of molten steel and impact pad 20 are discussed in more detail below.

The tundish 10 further includes a wear 26 separating the tundish 10 into left and right (first and second) compartments 18a and 18b, and the shock pad 20 is shown in FIGS. 1 and 2 . It is placed in the right compartment 18a on the tundish floor 16 . The bottom of the weir 26 includes a passage 26a for allowing fluid communication between the molten steel in the right and left compartments 18a, 18b. A diffuser 28 is positioned on the tundish floor 16 in the right compartment 18a between the wear 26 and the tundish shock pad 20 . A dam 30 having a plurality of cylindrical passages 30a sloping upward (from right to left in the flow direction) is disposed on the tundish bottom 16 in the left compartment 18b. On the opposite side of the dam 30 from the weir 26 , a stopper rod 32 is aligned with an outlet or tundish well block 34 through which the molten steel is discharged from the tundish 10 . The upward and downward movement of the stopper rod 32 controls the outflow of molten steel from the tundish 10 to the mold (not shown).

The tundish shock pad 20 may be made of materials or materials suitable for its intended use in a mold tundish for machining molten steel. Typically, such materials have high impact and abrasion resistance, high temperature strength and fire resistance, and good castability. Metals, ceramics and ceramic coated sands are examples of suitable materials. As a specific, but non-limiting example, a low-moisture high alumina castable composition such as Narcon 70 Castable and a coarse high alumina low cement castable composition such as Versoflow ^® 70C Plus are used as tundish impact pads 20 . It is a refractory material suitable for: According to the product description: Narcon 70 Castable (calcined basis) contains 26.9% silica (SiO ₂ ), 69.8% alumina (Al ₂ O ₃ ), 1.7% titania (TiO ₂ ), 0.8% iron oxide (Fe ₂ O). ₃ ), 0.7% lime (CaO), and 0.1% alkali (Na ₂ O); Versaflow ^® 70C Plus contains (as defined) 27.5% silica (SiO ₂ ), 67.3% alumina (Al ₂ O ₃ ), 2.1% titania (TiO ₂ ), 1.2% iron oxide (Fe ₂ O ₃ ), 1.6 % lime (CaO), 0.1% magnesium (MgO), and 0.2% alkali (Na ₂ O + K ₂ O). The body portion of the tundish shock pad 20 may be coated with a sedimentation resistant material to form a corrosion-resistant coating for receiving and contacting the incoming ladle stream 24 . Corrosion resistant coatings may include medium emissivity materials (e.g., zirconia, yttria, silicon carbide), high reflectivity materials (e.g., aluminum and alumina), or high temperature, non-oxide lubricants (e.g., nitrided boron).

3-6, the tundish shock pad 20 includes a circular base 40 (for top or bottom view). The base 40 includes a conical impact surface area 42 and an upper base surface having an adjacent annular base surface area 44 concentrically surrounding the conical impact surface area 42 . In the illustrated embodiment, the conical impact surface area 42 is not rounded. Optionally, the top of the conical impact surface area 42 may be slightly rounded while still maintaining the conical shape. As best shown in FIG. 5 , the conical impact surface area 42 extends upwardly terminating at an apex or vertex 46 . The conical impact surface area 42 is rotationally symmetric about an imaginary axis Az ( FIG. 5 ) passing through the apex 46 . In the illustrated embodiment, the conical impact surface area 42 has a linear profile or cross-section as best shown in FIG. 5 . The bottom face of the linear profile of the conical impact surface area 42 terminates at the outer perimeter 48 adjacent to and in contact with the radially inner cross-section of the annular base surface area 44 . The top of the linear profile of the conical impact surface area 42 terminates at a point corresponding to the apex 46 coincident with the axis Az. The annular base surface area 44 may lie in a horizontal plane that is at least partially flat and parallel to the bottom surface 40a of the base 40 .

The tundish shock pad 20 further comprises a side wall 50 having a side wall inner surface 52 which, as in FIG. 4 , itself continuously/infinitely circles and appears annular when viewed from above. The sidewall 50 is shown to have a uniform thickness over its entire 360°. The sidewall inner surface 52 is located concentrically and generally perpendicular to the outside of the annular base surface area 44 . As best seen in the cross-section of FIG. 5 , the sidewall inner surface 52 includes curved transition regions 54 and 56 on its bottom and top, respectively. The curved transition regions 54 and 56 may be symmetrical to each other. The ends of the lower curved transition region 54 are coplanar with the annular base surface area 44 and the sidewall inner surface 52 . The lower curved transition region 54 continuously curves between the base 40 and the sidewall inner surface 52 .

The tundish shock pad 20 further includes an upper wall 60 generally perpendicular to the sidewall 50 to extend inwardly from the upper transition region 56 and terminate at an inner end 62 . Upper transition region 56 continuously curves between sidewall inner surface 52 and upper wall 60, the ends of which consist of a curved undercut contiguous coplanar with sidewall inner surface 52 and upper wall 60. do. The inlet opening 64 defined by the inner end 62 is spaced upwardly relative to and centered on the apex 46 . In use, the inlet opening 64 is below and coaxial with the ladle shroud 22 to receive the incoming ladle stream 24 . In the illustrated embodiment, the diameter of the inlet opening 64 is approximately equal to or less than the diameter of the perimeter 48 of the conical impact surface area 42 .

The top wall 60 includes a lip 66 that is angled inwardly and downwardly to terminate at an interior end 62 . The upper wall 60 is substantially horizontal and has a first lower surface area 60a extending parallel to the lower surface 40a, and a second lower surface area corresponding to the lower surface of the lip 66 (referred to herein as the lower lip surface). (66a). The lower lip surface 66a slopes radially inwardly and downwardly from the first lower surface area 60a towards the conical impact surface 42 . 4 and 5, the first lower surface area 60a and the lower lip surface 66a delimit at 60b.

The base 40, sidewall 50 and top wall 60 may be integral, ie, may be a single piece or an integral part. Alternatively, the base 40 , sidewall 50 , top wall 60 , and/or other portions of tundish 10 may be formed as separate pieces joined together temporarily or permanently. The conical impact surface area 42, the annular base surface area 44, the continuous sidewall inner surface 52, the curved transition surface areas 54, 56, and the lower surface areas 60a, 66a are the axis ( Az) to form a continuous annular chamber with a cavity.

Referring to FIG. 7 , the liquid steel is injected into the tundish 10 through a shroud or sprue 22 as an incoming ladle stream 24 . It has been found that the ratio (D _j /D _m ) of the diameter (D _j ) of the inner diameter of the shroud 22 to the diameter (D _m ) of the inlet opening 64 in the range from about 0.3 to about 0.4 gives particularly good results. . Ladle shroud 22 and inlet opening 64 are coaxially aligned with each other in an exemplary embodiment. The design of the exemplary embodiment described herein causes the incoming ladle stream 24 to divert radially outward towards the lower transition 54 and sidewall inner surface 52 to impinge on the conical impact surface area 42 . . The shape of the continuous annular chamber forces the molten steel flow in a reverse direction towards the incoming ladle flow 24 to reduce turbulence and dissipate the energy of the molten steel before flowing from the shock pad 10 . The reversed fluid flow exits upwardly through the inlet opening 64 and then generally radially outward in all directions towards the wall of the tundish 10 as a substantially laminar flow. By providing an inlet opening 64 with a diameter greater than the diameter of the shroud 22 , an annular upward flow is created between the inlet ladle stream 24 and the inner end 62 .

Molten steel is discharged from the inlet opening 64 into the first compartment 18a. The continuous inflow of the incoming flow and removal of the molten steel through the outlet 34 causes the molten steel in the compartment 18a to flow through the weir passage 26a towards the weir 26 . After passing through the weir passage 28 , the molten steel flows through the dam 30 and/or the cylindrical passage 30a before being discharged through the output 34 .

A self-braking effect of the molten steel flow occurs. As a result, the outflow flow of the molten steel through the inlet opening 64 into the first compartment 18a is less turbulent and less energetic. The aforementioned “open-eye” and splashing problems are thereby significantly reduced.

In certain embodiments designed to suppress “open-eye”, conical impact surface area 42 is measured from a horizontal plane with perimeter 48 to an inclined plane with conical impact surface area 42 in a range from about 15 degrees to about 25 degrees. has a conical angle ? (Fig. 5). In another specific embodiment designed to suppress “open-eye”, lip 66 has a downward lip angle ( θ). In another specific embodiment designed to suppress “open-eye”, the continuous annular chamber has a radius of curvature of about 30 mm. These exemplary embodiments may be implemented individually or together with each other in any combination. The impact chamber may have a height equal to or greater than the inner diameter of the shroud to effect flow control.

Simulations of computational fluid dynamics (CFD) were performed on shock pads designed according to the above parameters. The areal average velocity, a measure of the injection-side flow activity of the upper face of the steel body, yields about 50% or less in practicing embodiments of the present invention compared to a flat petal shaped shock pad. The probability of forming an “open eye” is calculated to be reduced by the same proportion. Using CFD analysis where velocity and area were calculated for a cell of mesh and area average velocity, the area average velocity is determined as follows:

Area average speed

In general, it has been found that higher areal average velocities correspond to higher tundish flux entrainment and lower quality steel, whereas lower areal average velocities correspond to less tundish flux entrainment and higher quality steel. Therefore, a reduction of about 50% of the areal average velocity constitutes a significant reduction in the tundish flow inflow and leads to a high quality steel product. Without wishing to be bound by theory, it is presumed that the improved quality obtained using the exemplary embodiments described herein is due to one or more of the following: reduced turbulence due to high-velocity inlet flow and a “self-braking” effect; Less scattering during start-up and continuous operation; longer residence time of molten steel in the reservoir; promotes impurity and particle flotation; and more uniform storage temperature.

8 and 9 show a shock pad according to another embodiment. For brevity, the following description focuses on the differences between FIGS. 8 and 9 and the other exemplary embodiments described above. The same reference numerals denote the same or corresponding parts in different exemplary embodiments.

8 and 9 , the projections 80 are distributed at 360 degrees about the lower lip surface 66a. The protrusions 80 may be uniformly distributed like a matrix pattern or randomly distributed. In the above-described embodiment, the outer surface of the protrusion 80 has a hemispherical shape. However, the protrusion 80 may take other shapes. Moreover, the protrusions 80 may have the same or different shapes with respect to each other. It has been found that, in particular, the protrusion 80 , which is a hemispherical projection, further slows down the outflow flow of the liquid cavity as it exits the shock pad 20 through the inlet opening 64 . Additionally or alternatively, the protrusions 80 may be located anywhere on the inner surface of the shock pad 20 .

The foregoing detailed description of specific exemplary embodiments has been presented for the purpose of illustrating the principles and practical application of the present invention, thereby enabling those skilled in the art to understand the various embodiments of the invention, and various modifications suitable for the particular use are contemplated. can be This description is not necessarily intended to be exhaustive or to limit the invention to the precise embodiments disclosed. The specification sets forth specific examples for the achievement of a more general purpose that may be achieved otherwise.

Claims using the word “means” are to be construed only in 35 USC 112, sixth paragraph. Moreover, limitations in the specification are not recited in any claims unless they are explicitly included in the claims.

10: tundish 18: storage tank
18a, 18b: compartment 20: shock pad
22: ladle shroud 40: base
42: conical impact surface area 44: annular base surface area
50: side wall 54, 56: transition region
60: upper wall 64; entrance opening
66: lip 80: protrusion

Claims (21)

In the tundish shock pad,
a base having a base surface comprising a conical impact surface area defining an apex;
side wall; and
A top wall comprising a lip extending inwardly relative to the sidewall and sloping radially, inwardly and downwardly towards a conical impact surface area spaced above the apex and terminating at an inner end defining an inlet opening positioned centered therein. Tundish shock pad comprising a. The incoming ladle flow of molten liquid steel as recited in claim 1, wherein said sidewall comprises a continuous sidewall inner surface radially outwardly of said base surface, said top wall, together with said base surface and said continuous sidewall inner surface, in cavity. A tundish shock pad comprising a lower surface defining a continuous annular chamber configured to reduce turbulence of the tundish. 3. The method of claim 2, wherein the base surface further comprises a first planar annular region between the conical impact surface area and the continuous sidewall inner surface;
the top wall includes a second planar annular region extending between the continuous sidewall inner surface and the lip;
The first and second planar annular regions are spaced apart from and extend in a plane parallel to each other. The tundish shock pad of claim 1, wherein the conical impact surface area has an axis through a vertex at which the conical impact surface area has rotational symmetry. 5. The tundish impact pad of claim 4, wherein the conical impact surface area has a linear profile. 6. The conical impact surface area of claim 5, wherein the conical impact surface area has a cone angle lying in the range of about 15 degrees to about 25 degrees, measured from a horizontal plane having a perimeter of the conical impact surface area to an inclined plane having a linear profile of the conical impact surface area. tundish shock pad with The tundish shock pad of claim 1 , wherein said rib has a downward lip angle measured from a horizontal plane to a lower surface of said rib in a range of about 20 degrees to about 25 degrees. The continuous annular chamber of claim 1, wherein the sidewall includes a continuous sidewall inner surface radially outwardly of the base surface, and wherein the top wall jointly with the base surface and the continuous sidewall inner surface has a radius of curvature of about 30 mm. Tundish shock pad comprising a lower surface forming a. The tundish shock pad according to claim 1, wherein the projections are distributed around the area of the lower surface of the lip. The tundish shock pad according to claim 9, wherein the protrusion has a hemispherical shape. In the device,
a continuous caster tundish for receiving a reservoir of molten metal having a fluid flow created by an incoming ladle flow; and
Device comprising a tundish shock pad according to any one of the preceding claims. A strand casting method comprising:
Supplying an incoming ladle flow of molten liquid steel to a continuous casting machine tundish, the continuous casting machine tundish comprising a tundish shock pad,
a base having a base surface comprising a conical impact surface area defining an apex;
side wall; and
a top wall spaced upwardly relative to the apex and centered thereon and extending inwardly with respect to the side wall to terminate at an inner end defining an inlet opening disposed to absorb incoming ladle flow, the top wall having a conical impact a lip that slopes radially inwardly and downwardly towards the surface area;
impacting an incoming ladle stream of molten liquid steel against a conical impact surface area; and
A strand casting method, characterized in that the impinged molten liquid steel is discharged from the tundish impact pad through an inlet opening. 13. The ladle of claim 12, wherein said sidewall comprises a continuous sidewall inner surface radially outwardly of said base surface, said top wall co-located with said base surface and said continuous sidewall inner surface, an incoming ladle of continuous molten liquid steel. A method comprising a continuous annular chamber configured to reduce turbulence of flow. 14. The method of claim 13, wherein the base surface further comprises a first flat annular region between the conical impact surface area and the continuous sidewall inner surface;
the top wall includes a second flat annular region extending between the continuous sidewall inner surface and the lip;
wherein the first and second flat annular regions extend in and spaced from and parallel to each other planes. 13. The method of claim 12, wherein the conical impact surface area has an axis through a vertex at which the conical impact surface area has rotational symmetry. 16. The method of claim 15, wherein the conical impact surface area has a linear profile. 17. The strand according to claim 16, wherein the conical impact surface area has a cone angle measured from a horizontal plane having a perimeter of the conical impact surface area to an inclined plane having a linear profile of the conical impact surface area in a range from about 15 degrees to about 25 degrees. casting method. 15. The strand according to any one of claims 12 to 14, wherein the lip has a downward lip angle measured from the horizontal plane of the lip to the lower surface in the range of about 20° to about 25°. casting method. 15. A method according to any one of claims 12 to 14, wherein the upper wall includes a lower surface, together with the base surface and the continuous side wall inner surface, forming a continuous annular chamber having a radius of curvature of about 30°. strand casting method. 15. A method according to any one of claims 12 to 14, further comprising a projection distributed in the region of the lower surface of the lip. 21. The method of claim 20, wherein the projection is hemispherical.

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