Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED TUNDISH IMPACT PAD AND METHOD
BACKGROUND OF THE INVENTION
This invention is directed to apparatus for reducing surface turbulence in a molten metal
bath, and more particularly, to impact pads for reducing surface turbulence generated by
an incoming ladle stream in a continuous caster tnn~ h.
Tlln(li.~h~s are located between the ladle delivering liquid steel to the caster and the mold
that forms the product. They are large containers for holding a reservoir of liquid steel.
The liquid steel is ~ r~lled from the ladle through a nozzle extending into the t~ln~ h,
and the liquid steel is fed at a continuous or semicontinuous flow controlled by a stopper
rod, or by a slide gate assembly.
Extensive water flow-model studies have been con(lucted in the past, and continue to be
con~ cted today, to develop both methods and appald~us for reducing surface turbulence
in the tundish and improving the microcle~nlin~ss of steel products. These watermodelling tests have been beneficial in d~lel "~inil~g critical areas of tundish design such
as depth of bath, well block locations, and placement of fluid flow control devices within
the tl-n~ h As a result of such studies, it is well-known that the fluid flow generated by
the incoming ladle stream is reflected from the flat tundish floor toward the surface of the
liquid steel. This generated fluid flow causes a turbulent boiling action and extensive
wave motion at the surface of the steel bath. Additionally, where the fluid flow forces are
obstructed by structural barriers such as tundish side and end walls, the fluid flow surges
upward along such barriers and causes excessive turbulence at the surface of the liquid
steel bath. The excessive turbulence produced by the upward surge breaks up the tundish
flux cover and produces a dowllw~ld surge around the ladle nozzle. The broken flux
cover allows the liquid steel to be exposed to the atmosphere which sets up conditions
conducive to altering the chemistry of the steel bath. The chemical changes typically
involve loss of alllll-illll,,, from the bath and/or absorption of oxygen and nitrogen into the
2174266
steel. The dowllwald flow of the liquid steel swirling around the ladle nozzle entrains
particles of broken slag cover within the ladle stream.
Modern high quality steel product requirements dictate that hll~ulilies and chemical
changes cannot be tolerated. Heretofore, there have been various aLLelll~l~ to reduce or
elimin~te surface turbulence within the tundish to improve the quality of the fni.~h~(l steel
product. These attempts have included a wide assortment of dams and weirs which
redirect the ladle stream fluid flow away from the bath surface. One recent improvement
includes the development of an impact pad that elimin~tes surface boil by level~ g the
direction of the fluid flow gellel~l~d by the incoming ladle stream. United States Patent
No. 5,169,591 granted to Schmidt, et al. on December 8, 1992 discloses such a fluid flow
reversing impact pad. The Schmidt impact pad includes at least one sidewall having an
undercut portion that extends along the length of the inner surface of the sidewall, the
undercut being shaped to receive and reverse the direction of the fluid flow generated by
the incoming ladle stream. Schmidt's impact pad elimin~t~s surface boil, and has found
widespread use within the industry.
Some impact pad shapes produce high velocity steel flows within the tl-n~ h Highvelocity flow rates can cause "short circuiting," a term used to describe liquid steel
moving in a direct flow path from the ladle stream to the discharge nozzle of the t~ln~ h
Short circuiting reduces the Illil~i,,,,,,,l residence time of the liquid steel in a tundish and
can cause large inclusions to be carried into the caster mold. Instead of using the entire
tundish volume for flow, fast moving liquid steel travels along the bottom of the tundish
directly to the discharge nozzle, bypassing the majority of the tlm~ h. This creates dead
zones within the tl-ntli~h, and reduces inclusion float-out to the slag cover at the bath
surface. The dead zone areas freeze up and produce skull. Such conditions reduce the
quality and microcle~nlinf~-ss of the finished steel product.
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We have discovered that the above problems can be overcome by casting the refractory
material to provide an impact pad shape that reduces the velocity of the steel flowing from
the impact pad area.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to improve the microcle~nlintoss of a steel product
by reducing the velocity of the liquid steel fluid flow exiting a tundish impact pad.
It is a further object of this invention to improve the microcle~nlin~ss of a steel product
by increasing the liquid steel retention time in a tundish to enhance inclusion float out.
And finally, it is a further object of this invention to improve the microcle~nlin~ss of a
steel product by preventing short circuiting and eli~ g or reducing the dead zones
within a liquid steel bath contained in a tlln~ h.
We have discovered that the foregoing objects can be ~ in~-l with a tundish impact pad
comprising a base having an impact area upon which a liquid steel stream from a ladle
impacts, and at least one sidewall extending in an upward direction along the periphery
of the base, the bounds of the sidewall defining a volumetric area for receiving the liquid
steel and having an increasing cross-section in a direction away from the impact area of
the base.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 IS a plan view showing the pler~lled embodiment of the impact pad
lnvention.
Figure 2 is an elevation view of Figure 1 in cross-section.
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- 4 -
Figure 3 is an isometric view of Figure 1.
Figure 4 is a plan view of an alternate embodiment of the impact pad
invention.
Figure 5 is an elevation view of Figure 4 in cross-section.
Figure 6 is an isometric view of Figure 4.
Figure 7 is an isometric view of a still further alternate embodiment of the
impact pad invention.
Figure 8 is an elevation view of Figure 7 in cross-section.
Figure 9 is a plan view Figure 7.
Figure 10 is an elevation view in cross-section showing the impact pad of
Figure 1 placed in a continuous caster tlln~ h.
Figure 11 is an elevation view in cross-section showing the impact pad of
Figure 4 placed in a continuous caster llln-lish.
Figure 12 is an elevation view in cross-section showing the impact pad of
Figure 7 placed in a continuous caster tlln~ h
Figure 13 is an elevation view in cross-section showing the impact pad of
Figure 1 in combination with a flow control dam placed in a
continuous caster t ln~ h.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The increased demand for cleaner steels has resulted in co"li",li~lg research to advance
methods and apparatus for improving the microcle~nlin~.ss of certain steel grades. One
such advancement in the art is the discovery of an impact pad for receiving and reversing
the fluid flow generated by an incoming ladle stream as taught in the prior U.S. patent
5,169,591. It has now been discovered that the microcle~nlin~-ss of liquid steel can be
further improved by reshaping such fluid flow reversing pads to reduce the velocity of the
liquid steel flow exiting the impact pad into the main body of a tlmtli~h. It has also been
discovered that microcle~nlinl~s~ may be further improved by providing additional flow
control devices, such as dams, downstream from the reshaped impact pads. The
dowl~lealll flow control devices redirect the liquid steel flow into dead zones within the
steel bath. This prevents freeze up and ~lling within the dead zones, and improves the
quality of the finished steel product.
Referring to Figures 1 through 3 of the drawings, the impact pad 1 of the plefelled
embodiment is a shaped refractory brick or block m~mlf~ red from a castable highalumina refractory material capable of resisting erosion from an incoming ladle stream
impacting upon the pad. The impact pad is shaped to dissipate the kinetic energy in a
liquid steel flow generated by the incoming ladle stream and reduce its velocity. The
refractory impact pad shape includes a base 2, a sidewall 3, a closed end 4, and an open
end 5 opposite closed end 4. The open end 5 provides an exit to discharge the liquid steel
flow from the impact pad. Sidewall 3 extends in an upward direction along the periphery
of base 2 and includes an outside surface 6, an inside surface 7 a top 8 and an undercut
10 that extends along the inside surface 7 of sidewall 3. Top 8 includes a peripheral
surface defining an opening 11 through which an incoming ladle stream is directed.
Opening 11 exposes base 2 and provides a large target area for an incoming ladle stream
to impact upon the base. Opening 11 extends from a position adjacent the closed end 4
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and commllnicates with open end 5.
The bounds of sidewall 3, and the space between base 2 and undercut 10 define a flow
area "A" for receiving the liquid steel flow generated by the incoming ladle stream that
impacts upon base 2 of the pad. The inside surface 7 of sidewall 3 and undercut 10 are
flared in a bell like shape to create a continuously increasing llal~velse cross-section along
the length of the flow area "A" As a result, the transverse cross-section adjacent closed
end 4 is smaller than the cross-section at open end 5.
As more clearly shown in Figure 2, the geometry of the base sidewall and top forms the
bell like shape or flow area that extends from the ladle stream impact area to the open end
5. The height of sidewall 3 adjacent the closed end 4 is smaller than the height of the
sidewall at the open end 5. This dirr~lellce in height along sidewall 3 causes undercut 10
to be inclined in an upward direction away from the closed 4 end toward the open end 5.
The upward pitch of the undercut gives a closed end height "h" that is less than an open
end height "H". Additionally, the inside surface 7 of sidewall 3, as well as the legs 12 of
opening 11, are angled in an outward direction away from the closed end 4 toward the
open end 5. As shown in Figure 1, the angled sidewall surface 7 gives a closed end
sidewall width "w" that is less than an open end sidewall width "W", and the angled legs
of opening 11 give a closed end opening "o" that is less than the open end opening "O".
It should also be noticed that sidewall 8 may include end portions 9 that have an inside
surface that is not parallel to inside surface 7. The end portions 9 are adjacent open end
5, and they are shaped to direct the liquid steel in a flow direction substantially parallel
to the tundish sidewalls after the steel is discharged from the impact pad. This prevents
the liquid steel from ~m~hing into the refractory lining of the sidewalls, and it reduces
erosion and premature wear on the lining.
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- 7 -
As heretofore disclosed, the transverse cross-section along the flow area "A" increases
continuously from closed end 4 toward open 5 of the impact pad. This dissipates the
kinetic energy as the liquid steel flow moves from the smaller cross-section adjacent closed
end 4 toward the largest cross-section at the open end 5. As the energy of the liquid steel
flow decreases due to its expanding cross-section, the velocity of the liquid steel flow
decreases, and the steel is discharged from open end 5 at a reduced velocity. Additionally,
because the undercut 10 is inclined in an upward direction away from closed end 4 toward
open end 5, and because end portions 9 are substantially parallel to the tundish sidewalls,
the liquid steel flow is forced to move away from the impact pad in an upward direction
that is substantially parallel to the tundish sidewalls. This causes the liquid steel to flow
toward dead zones normally found at the discharge end of a ~lnfli~h. The slower upward
flow pattern avoids short Cif~;ui~ g within the tundish and provides effective retention time
to improve inclusion float-out to the slag cover on the surface of the heat. Freeze-up and
.skllllin~ within the tundish are also reduced because the improved flow uses a larger
portion of the tundish for circ~ ting the steel. As a result, a cleaner steel product is
produced.
Referring to Figures 4 through 6 of the drawings, an alternate embodiment of the impact
pad invention is shown coll-p-ising an impact pad 20 having a base 21 and a first sidewall
22 parallel to a second sidewall 23. The parallel sidewalls 22 and 23 extend in an upward
direction along opposite sides of the base 21, and each sidewall includes an outside surface
24, an inside surface 25, and a top 26. The two top portions 26 extend inward from
sidewalls 22 and 23 and provide an undercut 28 along the inside surface 25 of both
sidewalls. A longihl(lin~l opening 29 extends between the opposed undercuts 28 to expose
the impact area 32 of base 21 and provide a large target for an incoming ladle stream.
Impact pad 20 is flared in a double bell like shape to provide an increasing transverse
cross-section in two directions. The first bell like shape includes a flow area "Aa" that
extends from the impact area 32 toward a first open end 30, and the second bell like shape
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includes a flow area "Ab" that extends from the impact area 32 toward a second open end
31 opposite the first open end 30. The size of the transverse cross-section of both flow
areas increases in the direction away from the impact area 32 toward both respective open
ends 30 and 31. As more clearly shown in Figure 5, sidewalls 22 and 23 increases in
height in a direction away from the impact area 32 toward each open end 30 and 31. The
difference in sidewall height causes the opposed undercuts 28 to be inclined in an upward
direction away from the impact area 32 toward both open ends 30 and 31. This gives an
impact area height "h" that is less than both open end heights "H". Additionally, sidewalls
22 and 23, as well as the legs 33 of opening 29, are angled in an ou~w~d direction away
from the impact area 32 toward the open ends 30 and 31. As shown in Figure 4, the
angled sidewalls give a sidewall width "w" adjacent the impact area that is less than a
sidewall width "W" at both open ends 30 and 31, and the angled legs 33 give an opening
width "o" adjacent the impact area that is less an opening "O" at both open ends.
The transverse cross-section of both flow areas "Aa" and "Ab" increases continuously
from the impact area 32 toward both open ends 30 and 31. The increasing cross-section
causes a decrease in the kinetic energy of the liquid steel flow as it moves from the smaller
cross-section at the impact area 32, toward the larger cross-sections adjacent both open
ends 30 and 31. As the kinetic energy of the liquid steel flow decreases due to its
increasing cross-section as it moves along the length of flow areas "Aa" and "Ab", the
velocity of the liquid steel flow decreases, and the steel exits both open ends 30 and 31 at
a reduced velocity. Additionally, because the undercuts 28 are inclined in an upward
direction away from the impact area 32 toward both open ends 30 and 31, and because end
portions 27 are substantially parallel to the tundish sidewalls, the liquid steel flow is forced
to move away from the impact pad in an upward direction that is substantially parallel to
the tundish sidewalls. This causes the liquid steel to flow toward dead zones normally
found at the opposite discharge ends of the tlln~ h The slower upward flow patterns
avoid short c~l~;uiLillg within the tundish and provides effective retention time to improve
inclusion float-out to the slag cover at the surface of the heat. Freeze-up and ~ lling
217g266
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- 9 -
within the tundish are also reduced because the improved flow uses a larger portion of the
tundish for circulating the steel. As a result, a cleaner steel product is produced.
Although Figures 4 through 6 show the flow areas "Aa" and "Ab" being the same size and
shape, it should be understood that one of the open ends 30 or 31 could be larger than the
opposite open end to provide a larger flow area along one half of the impact pad. Such
variations in the flow areas enable the impact pad to be designed to meet dirrelellt flow
pattern requirements that may exist at opposite ends of a continuous caster t ln~ h.
Referring now to Figure 7 through 9 of the drawings, a still further alternate embodiment
of the impact pad invention is shown C~ lisillg an impact pad 40 having a base 41, a top
45, and a sidewall 42 including an outside surface 43 and an inside surface 44. The
sidewall extends continuously along the periphery of the base 41 between the base 41 and
top 45, and the top extends inward from the sidewall to form an undercut that extends
along the inside surface 44 of sidewall 42. The top 45 also includes a peripheral surface
that defines an opening 49 through which an incoming ladle stream is directed to impact
upon base 41.
Impact pad 40 is also flared in a double bell like shape similar to the embodiment shown
in Figures 4-6. However, the continuous sidewall 42 provides no open ends to discharge
the liquid steel flow from the impact pad, and the liquid steel is required to exit through
opening 49. The closed bell like shape of impact pad 40 includes an impact area 52 for
receiving the incoming ladle stream, a first exit end 50, and a second exit end 51 opposite
the first exit end 50. The double bell like shape provides two flow areas "Aa" and "Ab"
along the length of the impact pad 40. Similar to the previous embodiments, the flared
shape of the flow areas provides an increasing cross-section in a direction away form the
impact area 52 toward both exit ends 50 and 51. Flow areas "Aa" and "Ab" are both
shaped to receive the liquid steel stream flow generated by the incoming ladle stream
imp~rting upon the impact area of base 41 and direct it toward the larger cross-sectional
217426~
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areas at both exit ends 50 and 51.
Impact pad 40 is similar to the above embodiments in that sidewall 42 also increases in
height in a direction away from the impact area 52 toward both exit ends 50 and 51. The
difference in height along sidewall 42 causes undercut 47 to be inclined in an upward
direction away from the impact area 52 toward both closed exit ends 50 and 51. This
gives an undercut height "h" adjacent the impact area that is less than undercut height "H"
at both exit ends. Additionally, the inside surface 44 of sidewall 42 is angled in an
oulwdrd direction away from the impact area 52 toward both exit ends 50 and 51, and the
opening 49 is also angled in an ~ulward direction from the impact area 52 toward both exit
ends 50 and 51. The angle of the inside wall surface 44 gives a sidewall width "w"
adjacent the impact area that is less than a sidewall width "W" at both exit ends.
Likewise, the angle of opening 49 gives an opening width "o" adjacent the impact area that
is less than an opening width "O" at both exit ends 50 and 51.
The increasing size of the transverse cross-section along the length of both flow areas
"Aa" and "Ab" dissipates the kinetic energy in the liquid steel flow gelleldl~d by the
incoming ladle stream. The kinetic energy is dissipated as the liquid steel flow moves
from the smallest flow area cross-section adjacent the impact area 52 toward the largest
flow area cross-sections at both exit ends 50 and 51. As the kinetic energy is dissipated
the velocity of the liquid steel flow is decreased, and the steel exits the impact pad at or
near the opening width "O" of opening 49. The liquid steel flow exits the impact pad
through opening 49 in an upward direction at a reduced velocity. The slower upward flow
pattern avoids short cir~;uilil1g within the tundish and provides effective retention time to
improve inclusion float-out to the slag cover on the surface of the heat. Freeze-up and
~kl-lling within the tundish are also reduced because the improved flow uses a larger
portion of the tundish for circulating the steel. As a result, a cleaner steel product is
produced.
217g26~
Although Figures 7 through 9 show the flow areas "Aa" and "Ab" being the same size and
shape, it should be understood that either one of the exit ends 50 or 51 could be larger
than the opposite exit end to provide a larger flow area along one half of the impact pad.
Such variations in the flow area enable the impact pad to be designed to meet dirrelellL
flow pattern requirements at opposite ends of a continuous caster tundish.
Each of the above three impact pad embodiments, shown as impact pads 1, 20 and 40
respectively, have vertical sidewalls extending in an upward direction along the periphery
of the impact pad base. For example, in the pler~ d embodiment shown in Figures 1-3,
impact pad 1 includes a base 2, a top 8 and a sidewall 3. The sidewall extends along the
periphery of base 2 between the base and top surface 8. Sidewall 8 includes a shaped
inside surface 7 that receives and reverses the direction of a liquid steel flow gellel~t~d by
the incoming ladle stream impacting upon base 2. The plane of inside surface 7 intersects
the plane of base 2 and the plane of top 8 at a sharp angle of 90 or less to provide a sharp
angled undercut along the inside surface of the sidewall.
It has been discovered that if a flow reversing undercut has a sharp angle where the plane
of the sidewall intersects the plane of the top, and where the plane of the sidewall
intersects the plane of the base of the impact pad, energy (li~ip~tion is greater because the
sharp angles create an abrupt direction change that increases friction between the shaped
refractory and particles of liquid steel. The increased energy (li~ip~tion gellel~t~d by the
sharp angled undercut expends more kinetic energy than the stre~mlin~ undercuts that were
taught in the past. As a result the liquid steel flow is discharged from the impact pad at
a lower velocity than achieved by using past impact pad designs.
Referring now to Figure 10 of the drawings, impact pad 1 is shown placed within a
tundish 60 having a first end wall 61 opposite a second end wall 62. The impact pad is
located at the tundish end opposite the discharge well block 63, and the pad is positioned
to receive an incoming ladle stream 64 from a nozzle or ladle shroud 65.
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The incoming ladle stream impacts upon the base 2 and radiates in an oulwald liquid steel
flow "F" toward the sidewall 3. Undercut 10 reverses the r~ ting liquid steel flow back
into the incoming ladle stream, and friction between the undercut and liquid steel flow as
well as friction generated by collisions between the reversed liquid steel flow and the
S incoming ladle stream, dissipates the kinetic energy in the liquid steel. The flowing liquid
steel is contained within the flow area "A" and it moves in a direction away from the ladle
stream impact area toward open end 5. As the liquid steel flow moves along the flow area
toward the open end, its cross-section is increased because of the increasing shape of the
flow area "A". The increasing cross-section of the liquid steel flow dissipates additional
kinetic energy in the steel and further reduces the velocity of the liquid steel being
discharged from the impact pad. The steel exits opening 5 at a greater reduced velocity
than would be achieved by using only the reversing undercut shape of the impact pad.
Additionally, because the top of the impact pad inclined in an upward direction away from
closed end 4 toward open end 5, and because end portions 9 are substantially parallel to
the tundish sidewalls 66, the liquid steel flow is forced to move through the steel bath 67
in an upward direction that is substantially parallel to the tundish sidewalls. This causes
the liquid steel to flow toward dead zones normally found at the discharge end 62 of a
tlln(li~h. This slower upward flow pattern avoids short circuiting within the tundish and
provides effective retention time to improve inclusion float-out to the slag cover 68 at the
surface of the heat. Freeze-up and ~ lling within the tundish are also reduced because
the improved flow uses a larger portion of the tundish for circ~ ting the steel. As a
result, a cleaner steel product is produced.
Figure 11 shows impact pad 20 placed within a tundish 70 having at least two discharge
nozzles 71. Tundish 70 includes a first end wall 72 opposite a second end wall 73. The
impact pad is positioned between the discharge nozzles to receive an incoming ladle stream
74 from a nozzle or ladle shroud 75.
217~26S
The incoming ladle stream impacts upon the base 21 of the pad and ge~ dles a liquid steel
flow "F" that radiates ~uLwdld toward the undercut 28 extending along the inside surface
of sidewalls 22 and 23. The liquid steel flow is reversed back into the incoming ladle
stream by the undercut portion 28. As heretofore disclosed, the r~velsillg feature of
undercut 28 dissipates kinetic energy in the liquid steel flow, and the liquid steel flow is
contained within the flow areas "Aa" and "Ab" of the impact pad. The liquid steel flow
moves in a direction away from the ladle stream impact area toward both open ends 30 and
31. The increasing transverse cross-section along the lengths of the flow areas "Aa" and
"Ab" further dissipates kinetic energy within the liquid steel flow, and the steel exits the
pad through the open ends 30 and 31 at a greater reduced velocity as explained in the
plcl~ d embodiment.
The exiting liquid steel flow "F" enters the main body of the tundish in a direction
controlled by incline of undercut 28 and the angle of the inside surface 25. Additionally,
because the undercut 28 is inclined in an upward direction, and because end portions 27
are substantially parallel to the tundish sidewalls 78, the liquid steel flow is forced to move
through the steel bath 77 in an upward direction that is substantially parallel to the tundish
sidewalls. This causes the liquid steel to flow toward dead zones normally found at both
discharge ends 72 and 73 of the tlln(li~h. This slower upward flow pattern avoids short
circuiting within the tundish and provides effective retention time to improve inclusion
float-out to the slag cover 76 on the surface of the heat. Freeze-up and ~-llin~ within the
tundish are also reduced because the improved flow uses a larger portion of the tundish
for circul~ting the steel. As a result, a cleaner steel product is produced.
Figure 12 shows impact pad 40 placed within a tundish 80 having at least two discharge
nozzles 81. Tundish 80 includes a first end wall 82 opposite a second end wall 83. The
impact pad is positioned between the discharge nozzles to receive an incoming ladle stream
84 from a nozzle or ladle shroud 85.
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The incoming ladle stream impacts upon the base 41 of the pad and radiates ~ulward in
a liquid steel flow "F" toward the inside surface 44 of sidewall 42. The liquid steel flow
is reversed back into the incoming ladle stream by the undercut portion 47, and as
described above, friction between the undercut and liquid steel flow as well as friction
generated by collisions between the reversed liquid steel flow and incoming ladle stream,
dissipate the kinetic energy in the liquid steel.
As illustrated in the drawing, the flow areas "Aa" and "Ab" contain the liquid steel flow
within the impact pad, and the liquid steel flow moves in a direction away from the ladle
stream impact area 52 toward the exit closed ends 50 and 51. As the steel flow moves
toward the exit ends its cross-section is increased and kinetic energy is further dissipated.
The decrease in kinetic energy causes the velocity of the liquid steel flow to decrease as
it moves away from the impact area toward both exit ends, and the liquid steel flow is
discharged from the impact pad through opening 49 at opening width "O" located adjacent
both exit ends 50 and 51.
The exiting liquid steel flow "F" enters the main body of the tundish in an upward
direction at a more reduced velocity than would be achieved by using only the flow
reversing undercut feature without the increasing flow areas "Aa" and "Ab". Because the
flow moves in a slowed upward direction, the liquid steel moves through the steel bath 87
toward dead zones normally found at both discharge ends 82 and 83 of a tlmtli~h. This
slower upward flow pattern avoids short circuiting within the tundish and provides
effective retention time to improve inclusion float-out to the slag cover 86 on the surface
of the heat. Freeze-up and ~lllin~ within the tundish are also reduced because the
improved flow uses a larger portion of the tundish for circul~ting the steel. As a result,
a cleaner steel product is produced.
Figure 13 shows the plefell~d embodiment of the impact pad used in combination with at
least one additional flow control device 90 placed downstream from the impact pad. The
217426~
slower velocity of the liquid steel flow "F" exiting the open end of the impact pad allows
for better flow control of the liquid steel dowl~Llealll of the impact pad. Dam 90 redirects
the slower steel upward flow below the slag cover 91 without breaking up the slag cover.
Such a flow path enhances inclusion float-out and produces a cleaner steel product.
While this invention has been described as having a pl~r~lled design, it is understood that
it is capable of further modifications, uses, and/or adaptations following in general the
principle of the invention and including such depalLules from the present disclosure as
come within known or customary practice in the art to which the invention pertains, and
10 as may be applied to the essential features set forth herein, and fall within the scope of the
invention limited by the appended claims.
