JPH0462824B2 - - Google Patents

Abstract

A method is provided for directly casting molten metal (19) from the exit end (26) of a casting vessel (18) onto a moving casting surface (20) to form a continuous strip (15) of crystalline metal. The surface tension of the molten metal (19) flowing from the exit end (26) forms the top, edge and bottom surfaces of the strip (15) being cast to provide good strip surface quality, edges and structure. An apparatus is also provided including a casting vessel (18) having a molten metal receiving end (22) and an exit end (26) from which a fully developed uniform flow of molten metal (19) leaves through a U-shaped structure onto a moving casting surface (20). A direct cast strip product is also provided.

Description

[Detailed description of the invention]

INDUSTRIAL FIELD OF THE INVENTION The present invention relates to a method and apparatus for casting metal alloys directly from molten metal into continuous strips and to the strips produced by the method. More particularly, the present invention relates to feeding molten metal through an open outlet of a casting vessel to solidify a continuous strip of desired thickness on a moving casting surface. BACKGROUND OF THE INVENTION In the conventional manufacture of metal strip, such methods involve casting the molten metal into an ingot or billet or slab form and then typically casting the strip to provide the desired strip thickness and quality. Any of the various stages of the process include one or more hot rolling and cold rolling stages, as well as pickling and annealing stages. The cost of producing continuous strips, particularly in as-cast dimensions ranging from 0.010 inch to 0.100 inch (0.0254 cm to 0.254 cm), can be reduced by eliminating some of the process steps of conventional methods. The as-cast strip can be conventionally processed by cold rolling, pickling, and annealing to final dimensions of 0.002 inch to 0.040 (0.00508 cm to 0.1016 cm). Various methods and apparatus are known for producing direct cast strip. Typical examples of such methods include spraying the molten metal through a metering orifice and across a gap onto a rapidly moving quenching surface such as a wheel or continuous belt; partially submerging the molten metal into a rotating quenching surface pool. ; using a horizontally linked belt as a quenching substrate and solidifying the molten metal by flowing it onto this substrate; and casting with twin casting rolls with an intervening pool of molten metal. Attempts have long been made to cast molten metal directly through an orifice for mass production of strips of good quality and texture. U.S. Pat. No. 112,054, dated February 21, 1871, discloses a method for producing flat solder wire from molten metal pumped through an orifice onto a rotary casting surface. Similarly, in 1908
US Pat. No. 905,758, issued Dec. 1, discloses a method for drawing molten metal onto a casting surface from an outlet at the lower end of a vessel. British Patent No. 24320 dated 24 October 1910
No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, 2003, discloses a method for producing sheets or strips from molten metal flowing through a tube channel having at least one side in contact with a moving casting surface. A representative example of a more recent device is U.S. Pat. Discloses a method for continuously stretching the material by moving the front and solidifying it as a continuous product. The molten material is maintained in static equilibrium at the exit and maintained by gravity in continuous contact with the moving surface.
U.S. Pat. No. 4,221,257 to Narasimhan, issued September 9, 1980, relates to a method of pumping molten metal under pressure through a slotted nozzle onto the surface of a moving chill body. Orifice casting equipment generally has a thickness of approximately
Limited to thin, as-cast materials on the order of less than 0.010 inches (0.0254 cm). Such a device would be limited in size since the moving quench surface would be limited to what could solidify and transport the liquid as it is pumped out of the nozzle orifice. . Such a device acts as a melt pump, transporting excess melt from the orifice to the quenching surface in a molten state with more heat than can be extracted to produce the appropriate strip. Although such conditions can be overcome by reducing the delivery rate of the melt and/or by increasing the speed of the quenching surface,
As a result, it becomes thinner. When attempting to produce crystalline strip at high speeds in conjunction with orifice casting equipment, quality usually suffers. When the molten metal is sprayed onto a fast cooling surface or flowed across its width onto a slowly moving horizontal belt, the molten metal quickly leaves the source in a partially molten state. This is the case when quality deteriorates. This is because the strip rapidly solidifies from its quenched surface side and shrinkage occurs, which can only be relieved by a fresh supply of molten metal. Without such a fresh supply of molten metal, cracks will rapidly form within the structure of the strip, significantly impairing its physical properties. U.S. Patent No. issued June 23, 1981
No. 4274473 and the same No. 4274473 issued on September 23, 1981.
Attempts have been made to improve the nozzle geometry to overcome the problems associated with orifice casting, such as that shown in No. 4,290,476. A disadvantage of orifice casting is that the orifice meters the amount of molten metal which in effect determines the thickness of the strip. Moreover, the strip thickness is limited by the relatively high pressure head used to supply sufficient molten metal to the orifice and the relatively small spacing from the casting wheel to accommodate the molten metal. . For example, thicker strips can be produced on a single quench surface by dipping a slowly rotating quench wheel into statically fed melt to solidify a much thicker strip. The molten metal solidifies on the surface of the wheel and continues to thicken at a determinable rate until it exits the molten metal bath or leaves the surface. The fresh supply of molten metal avoids the formation of cracks typically associated with solidification of a limited layer, such as in orifice casting. Moreover, this extremely steep thermal gradient between the hot water pool and the solidification front results in a more uniform internal structure and superior top surface quality. Disadvantages of such immersion equipment are due to the difficulty in keeping the molten metal from solidifying on the edges of the slightly submerged quench wheel and the tendency to cast channel-like structures. There is. Added to this is the difficulty in ensuring uniform contact between the recessed strip and the surface of the quench wheel as it enters the molten pool, resulting in poor surface quality on the casting side of the strip. These problems result in variations in the thickness of the strip, resulting in thinner areas where intimate contact is reduced or eliminated. Other direct casting methods have been proposed but have not been developed into practical methods. For example, when pouring hot water onto the top of a moving casting wheel, the thickness is not uniform;
Strips are produced with weak edges and unacceptable quality. U.S. Patent No. 30 May 1911
No. 993904 discloses an apparatus having a first melt container with a gravity outlet opening into the lower part of the second tray-like container below the melt level. The molten metal is the second
The molten metal exits the vessel via overflow means which directs it to the casting wheel. U.S. Pat. No. 3,381,739, issued May 7, 1968, prepares sheets or strips of material by flowing a liquid around a wetted surface and filling the gap with the liquid to a moving surface for solidifying the liquid. Discloses a method of forming. What is needed is a method useful for commercial production that directly casts strips with surface quality comparable to or better than conventionally produced strips. The direct casting method and apparatus should produce strip superior to orifice casting and other known direct casting methods including immersion casting equipment, horizontal link belt quench equipment, and twin casting rolls. It is the aim of this method and device to overcome the disadvantages of known direct casting methods. Furthermore, 0.010 inch (0.0254 cm)
What is needed is a method and apparatus for directly producing relatively thick strips, on the order of about 0.100 inches (0.254 cm) or less. In order to improve the surface quality and texture of the strip, it is desirable to minimize or eliminate factors that contribute to shrinkage and cracking in direct cast strips. Additionally, methods and apparatus suitable for mass production of strips at low cost and for facilitating the manufacture of new alloys would be desirable. Direct cast strip should have good surface quality, edges and texture and have properties at least as good as conventional cast strip. SUMMARY OF THE INVENTION The present invention provides a method for directly casting molten metal into a continuous strip of crystalline metal, comprising a receiving end and an exit end having an edge disposed adjacent to and parallel to the casting surface. supplying molten metal to a receiving end of a casting vessel having a step of moving the cooled casting surface substantially upwardly past the outlet end;
supplying molten metal from a receiving end to an outlet end to provide a molten metal pool at the outlet end having a substantially uniform flow and a free top surface; The molten metal is supplied at the outlet end of the casting container by controlling the depth of the molten metal at the outlet end of the casting container and the distance between the exit end and the casting surface. and removing the cast strip from the moving casting surface. The invention also provides an apparatus for directly casting molten metal into a continuous strip of crystalline metal, comprising:
a casting vessel having a movable casting surface, a receiving end, an outlet end and an intermediate portion therebetween; and a device for supplying molten metal to the receiving end of the casting vessel, the casting vessel having a movable casting surface; an outlet end having a generally U-shaped structure adjacent to the casting surface with edges parallel to the casting surface; and an intermediate portion that facilitates a substantially uniform flow of molten metal from the receiving end to the outlet end. The U-shaped structure at the outlet end has a flat bottom wall and a flared inner wall that opens upwardly and has approximately the same width as the strip to be cast between the inner surfaces; The section has a constant width along the bottom wall between the inner surfaces of the sidewall sections and a uniform cross section over a sufficient length to form a substantially uniform flow of molten metal from the outlet end. The casting surface has an area from the outlet end to
0.005 inches to 0.060 inches (0.0127 cm to 0.1524 inches)
20 ft/min to 500 ft/min at a distance of
An apparatus is provided that is capable of moving generally upwardly past the outlet end of a casting vessel at a speed of 1,000 feet per minute (0.096 m/min to 152.4 m/min). Also provided is a continuous, direct cast strip product made in accordance with the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 generally shows a casting apparatus 10.
This casting device includes a transfer container 12 and a casting surface 2 for transferring the molten metal.
It has a feed tundish 14 for supplying molten metal to a casting vessel 18 for casting directly on the melt to produce a continuous product 15 in the form of a strip or sheet. Molten metal 19 is fed from vessel 12 to tundish 14 and from there to casting vessel 18 in a conventional manner. A stop rod 16 or other suitable device may control the flow of molten metal into the casting vessel 18, such as through the spout 17. Casting vessel 18 is shown generally horizontal and has a receiving end and an outlet end disposed adjacent casting surface 20 . The feeding of the melt 19 through the casting vessel 18 is accomplished by any suitable conventional method and device, such as a vessel, tundish or melt pump. Vessel 12 and feed tundish 14 may be of known design, but should be suitable for supplying the casting vessel with an adequate amount of molten metal to produce strip on the quench wheel. Additionally, the casting surface 20 may be conventional, but preferably takes the form of a continuous belt or casting wheel.
Preferably, Nakago wheels are used. Although some casting surfaces may yield good results, resuscitation of the casting surface is not believed to be critical to the present invention. The method and apparatus of the present invention utilize cast steel, carbon steel and stainless steel surfaces. It is important that the casting surface be able to move past the casting vessel at a constant velocity to provide the desired quench rate to remove sufficient heat to solidify the molten metal into a strip. The casting surface 20 is suitable for mass production of crystalline materials.
0 feet/min to 500 feet (6.096 m to
152.4 m) per minute, preferably ranging from 50 feet per minute to 300 feet per minute (FPM). The casting surface 20 should be sufficiently cold to provide rapid cooling of the melt, removing heat from the melt and solidifying the strip in crystalline form. The quenching rate provided by the casting surface 20 of the apparatus 10 is less than 10000°C 6/sec, generally preferably
Less than 2000℃/sec. Two important aspects of the casting surface are that the casting surface
8 and a free surface-like hot water pool at the outlet end. The free surface of the molten metal pool at the outlet end 26 is essential to achieving good top quality of the cast strip. "Free" means that the top surface is not constrained by the structure, i.e. is not in contact with the container structure and is free to seek its own level between the receiving portion 22 and the outlet end 26. It means that. Generally, the flow path is measured between the direction of metal flow at the free surface of the molten metal at the outlet end of the casting vessel 18 and the direction of movement of the casting surface at the free surface of the outlet end. Approximately 0° in the direction of metal flow from
An angle θ of 135° is attached. For the casting wheel, the flow path in the casting face is tangent to the free surface of the outlet end of the vessel 18. Preferably the angle is between 0° and 45° from the horizontal. For a casting wheel, the vessel is adjacent to a location in the upper quadrant of the wheel when the free surface of the molten metal is near the top of the casting wheel and at an angle of approximately 0°. Casting vessel 18 is essential to the method and apparatus of the present invention and is best shown in FIG. 2, which is an elevational view of vessel 18. Casting vessel 18 is positioned adjacent casting surface 20, is preferably substantially horizontal, and is constructed of an insulating and refractory material as described below. This configuration is necessary to provide the desired flow of uniform and well-formed metal to the casting surface 20. Melter 18 has a receiving end 22 at the rear portion and an outlet end 26 . Preferably, the receiving end 22 and the outlet end 26 have substantially the same cross-sectional area or, when measured perpendicular to the direction of metal flow from the receiving end 22 to the outlet end 26, the outlet end 26 has a larger cross-sectional area. Receiving end 22 is shown as being deeper than outlet end 26 to facilitate reception of molten metal 19 from, for example, supply spout 17 and to form a flow of molten metal to outlet end 26. The outlet end 26 of the container 18 has a generally U-shaped structure defined by a bottom wall portion 28 and a side wall portion 30, as shown in FIG. The sidewall portion 30 may have a vertical inner wall surface 31, and preferably the surface 31 of the sidewall 30 of the U-shaped structure flares upwardly to facilitate metal flow. This slight taper is at the exit end 2
6 tends to improve metal flow, but if the taper is too large it can cause loss of surface tension control and overflow of the molten metal. A taper of less than 10° per side, preferably between 1° and 5° is provided. Outlet end 26 has a bottom wall 28 .
has a generally planar interior portion of sufficient length to provide a substantially uniform flow of metal from the outlet. Preferably, the length of the flat wall section, measured in the direction of metal flow, is at least equal to the depth of the molten metal pool to be received at the outlet end 26. More preferably, the length to depth ratio is at least 1:1 or greater. Outlet end 26
has uniform width and height dimensions over the length of the flat interior surface of the bottom wall 28 to create a uniform cross-sectional area at the end. The width of the outlet end 26, as measured between the insides of the sidewalls 30 along the free surface of the molten metal pool, is approximately the same width as the strip to be cast. Preferably, the outlet end 26
is positioned adjacent to the casting surface 20, and U
Side wall portion 30 and bottom wall portion 2 forming a letter-shaped structure
The ends or edges of 8 are substantially parallel to the casting surface. To facilitate transitional flow between the receiving portion 22 and the outlet end 26, the receiving portion 22 and the outlet end 26 are arranged such that there is a substantially uniform flow at the outlet end 26.
There should be an intermediate portion 24 communicating between the two. Preferably, the intermediate portion 24 is connected to the receiving portion 22
It maintains a substantially uniform cross-sectional area over its entire length from to the outlet end 26. The intermediate section 24 shown in FIG. 3 extends from the receiving section 22 to the outlet end 2.
6 and has a depth that gradually increases to maintain a substantially uniform cross-sectional area throughout its length, as shown in FIG. The intermediate section 24 may include a tapered bottom wall 32 that gradually increases the depth of the container 18 from the receiving section 22 to the outlet end 26. Similarly, the intermediate portion 24 may have at least one sidewall 34 that flares outwardly from the narrow receiving portion 22 to provide a progressively increased width at the wide outlet end 26. Casting container 18 as described above
Due to the shape of the molten metal, the cross-sectional area of the flow of the molten metal at the outlet end is maintained substantially uniform during the supply of the molten metal from the receiving end to the outlet end. FIG. 2 is a plan view of casting vessel 18 showing sidewall 34 of intermediate section 24. FIG. In addition, in FIG. 2, the casting vessel 18 is provided with, for example, an intermediate portion 2, in order to weaken the flow of the molten metal in the casting vessel and facilitate the formation of a uniform flow at the outlet end.
4 or near where the section 24 joins the outlet end 26 indicates the advantage of using a dam or plate 36. The dam 36 should be made of a refractory or heat resistant material that also resists corrosion from molten metal. Kaowool refractory board treated with a diluted colloidal silica suspension was found to work well. The dam 36 may extend over the entire width of the casting vessel 18 or over a portion of its width. As shown in FIG. 2, preferably the level of molten metal in the receiving end 22 of the casting vessel 18 is about the same level as the molten metal at the outlet end 26. Weir 36 is useful to impede or restrict flow to facilitate the formation of a uniform and well-defined flow and to inhibit migration of surface oxides and slag. Figures 2a and 2b illustrate the use of tension in the flowing melt to form the surface of the strip being cast. Second
Figure a is a partial cross-sectional detail elevational view of the outlet end 26 adjacent the casting surface 20. The molten metal flowing from the outlet end 26 forms and maintains a meniscus 35 between the inner surface of the bottom wall 28 of the U-shaped structure and the casting surface. The surface tension that forms the meniscus 35 forms the bottom of the strip 15 being cast. The surface tension of the free surface of the molten metal pool at the outlet end 26 is U when forming a strip product.
A curved portion 39 is formed at the top of the molten metal within the glyph structure. FIG. 2b shows the outlet end 26 adjacent the casting surface 20.
, which shows the solidifying molten metal 19 seen from below the outlet end 26 therebetween. Molten metal 19
The surface tension creates a convex surface or meniscus 37 on the inner surface 31 of the side wall 30 near the bottom wall portion 28 between the outlet end 26 and the casting surface 20 . Preferred specific examples of the casting container 18 are shown in FIGS. 4 and 5.
The figure shows an elevation view and a plan view, respectively. Vessel 18 is shown having a metal support shell 38, refractory insulation 40, and liner 42, which constitutes the interior surface of casting vessel 18 and contacts the molten metal during casting. The container 18 should be made of a refractory material that is insulating and corrosion resistant to molten metal. The casting vessel may be secured to some suitable table or device for orienting and positioning it at the desired casting location on the casting surface or wheel 20. Outlet end 2 of casting vessel 18
6 is the front surface or edge 3 of the side wall 30 and bottom wall 28 forming a U-shaped structure that fits the contour of the casting surface.
Should have 3. This is done by using 60 to 100 grit silicon carbide abrasive paper held between the casting surface and the container assembly and rubbing the container 18 with the abrasive paper to create an edge parallel to the wheel. can be done. Zirconia cement is then brushed onto the front surface 33 of the casting vessel 18 and allowed to dry before casting. 4 and 5 illustrate a preferred embodiment of the casting container 18 of the present invention, which has a width of 4.
inch (10.16cm) and approximately 13 inches (33.02cm)
Useful for casting strips up to and width 48
It is also useful for casting strips up to 121.92 cm (121.92 cm). The metal support tube 38 may be used depending on the type of material used for the insulation layer 40. Heat insulation layer 40
is preferably a foamed ceramic bonded insulation requiring an external support such as metal support tube 38. Alternatively, the barrel 38 is not required if standard fire bricks or blocks are used, joined into the desired shape, and then carved to achieve the desired internal and external dimensions. Container 18 may also be a one-piece unit formed from a castable ceramic material. Liner 4 provided on the inner surface of casting container 18
2 is also made of an insulating refractory material that is resistant to molten metal. Casting vessel 18 saturated with diluted colloidal silica suspension
Insulating plankets of high alumina fiber-silicate compositions, such as the material named Fiberfrax, which are formed in-house and then dried prior to actual use have been found to be useful. 4 and 5 also show rear overflow element 44.
, this overflow element is a rear perspective surface 4 extending from the inner surface of the casting vessel 18 to the bottom wall of the vessel 18.
5. The height of the overflow element 44 determines the maximum depth of molten metal received in the receiving end 22 and, therefore, the depth of the molten metal within the outlet end 26 of the casting vessel 18. The overflow element 44 facilitates adjustment of the level of molten metal in the casting vessel 18, which is essential for controlling the thickness and quality of the casting strip. Also shown in FIG. 4 is casting vessel 18, which may optionally have a cover assembly 46 near intermediate portion 24 thereof. The cover 46 has a downwardly extending wall 4 joined by a bottom surface 52.
It has 8,50. a wall portion 48 extending downstream;
50 is similar to the weir shown in FIG. Cover 46 is typically constructed of a refractory insulation material that is resistant to molten metal. It consists of a cover 46, a liner 42, a fireproof heat insulating layer 40, and a metal outer cylinder 18, and has the same configuration as the casting container 18. While the presence of the cover is useful in retaining the heat of the molten metal in the casting vessel 18, the presence of the cover allows the receiving end 2 to maintain a free surface of the pool within the outlet end 26.
It is important that the molten metal in 2 and outlet end 26 not come into contact. The cover may also extend over part or all of rear receiving portion 22 to maintain a protective atmosphere. In operation of the casting apparatus of the present invention, vessel 12, tundish 14, and casting vessel 18 are preheated to operating temperature prior to introducing molten metal into the casting vessel for the production of strip material. Any conventional heating device is suitable and can be used. Using an air-acetylene or air-natural gas heating lance that is positioned at the receiving end 22 and constitutes a preheated front cover for the front edge of the casting vessel U-shaped structure located adjacent to the casting surface 20. . The standard preheating temperature for casting molten stainless steel is preferably about 1900° to 2000°C (1037.8°C to 193.3°C). After the desired minimum preheat level is reached, the heating lance is removed and the vessel 18 is positioned adjacent the casting surface at a predetermined spacing, for example between 5 and 20 mils. To begin the process of directly casting alloys from molten metal into a continuous strip, molten metal 19 is transferred from a bulk transfer vortex or vessel 12 to a feed tundish 1.
4 and then into a generally horizontally oriented casting vessel 18. The flow of molten metal from the supply tundish 14 to the casting vessel 18 is carried out through the spout 1 at the rear feeding or receiving end 22 of the casting vessel 18.
Adjustment is preferably made by means of a valve device such as a stop rod 16 via 7. As vessel 18 begins to fill with molten metal, the molten metal begins to flow in a direction toward the outlet end of the vessel and through intermediate section 24 and outlet end 26 as shown in FIG. The casting vessel 18 is operable to supply molten metal to an outlet end 26 thereof. The casting vessel 18 has an outlet end 2
A dam 36, as shown in FIG. 2, may be included to slow down or impede the flow of molten metal 19 to facilitate a uniform and well-defined flow at 6. The molten metal preferably maintains a substantially uniform cross-sectional area of flow from the receiving end 22 through the outlet end 26. Generally, the outlet end 26 is the receiving end 2
2, the U-shaped structure has a width approximately equal to the width of the strip to be cast. Casting container 18
has a casting volume with a tapered and flared middle section. The casting vessel 18 is designed to prevent cross-flow of the molten metal therein and to create a uniform turbulent flow from the outlet end 26 across the width of the U-shaped structure at the outlet end 26; The well-formed flow thus has different streamline velocities in the direction of flow from the receiving end 22 to the outlet end 26. The level of the molten metal at the outlet end 26 is the same as that at the receiving end 22.
However, the depth of the molten metal is shallower at the outlet end. The molten metal flows almost uniformly across the width of the U-shaped structure at the outlet end onto the structural surface 2.
It continues to flow from the outlet end 26 to the moving casting surface 20 so as to be brought to zero. The molten metal at the outlet end 26 has a top surface tension, and the molten metal exiting the opening has an edge surface tension, which partially form the ends and edges of the cast strip 15, respectively. The bottom surface is formed from surface tension in the form of a meniscus between the bottom inner surface of the U-shaped structure and the casting surface. Conjecture suggests that solidification of the molten metal leaving the outlet end of the vessel 18 begins as the molten metal contacts the casting surface as it leaves the bottom of the U-shaped opening in the outlet end 26 of the vessel 18. The thickness is solidified from the pool of molten metal available at the casting surface at the outlet end of the strip vessel 18 and is continuously provided with an excess of molten metal to the solidifying strip until it leaves the outlet end 26 of the vessel 18. arise. Such a molten metal pool will form a significant portion of the strip thickness when it contacts the moving casting surface 20, and only a small portion of the strip thickness will form a portion of the strip thickness adjacent to the top curved surface tension portion 39 of the vessel 18. It is thought to originate from molten metal that solidifies as it is drawn from the molten metal. It is estimated that more than 70% of the strip thickness, perhaps about 80% or more, also comes from the pool of molten metal fed adjacent the meniscus 35. The molten metal solidifies from the bottom of the U-shaped structure at the outlet end 26 of the vessel 18, with the molten metal being fed to the casting surface. The casting surface 20 extends upwardly from the bottom of the U-shaped opening at the outlet end 26 to the open top of the opening.
Pass by 8. The position of the vessel 18 relative to the casting surface 20 and the velocity of the casting surface are predetermined factors for achieving the quality and size of the casting strip.
If the casting surface 20 is a casting wheel, the container 18
is preferably positioned on the upper quadrant of the casting wheel. The method of the present invention allows for significant adjustment of several factors, thereby producing metal strips of desired dimensions in the range of 0.01 to 0.06 inches (0.0254 cm to 0.1524 cm) with good surface quality, edges and texture. can be cast. Adjustment of the flow rate of the molten metal onto the casting surface, velocity of the casting surface, solidification from the bottom of the molten metal pool, and adjustment to maintain the surface tension of the molten metal.Adjustment of the depth of the molten metal in the pool and its spacing from the casting surface. is an important correlation factor. The following examples are presented to better understand the invention. EXAMPLE A cast vessel having the general construction as shown in FIG. 2, except for having one dam plate 36 standing near the outlet end 26, is made of a hardened block of Kao wool refractory, a material of alumina-silica composition. It was composed of The cast container was dried overnight at 250 °C (121.11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111121111111111111112 250 degrees Celsius) (250 degrees)(250 |
Impregnated with time-dried colloidal silica suspension. The container was molded to the contour of the wheel and then the ends of the U-shaped structure were coated with a thin layer of zirconia cement. Weir sections of similar composition were used.
The casting vessel was then heated with an air-acetylene lance. Container 18 has a length of approximately 8.75 inches (22.225 cm) from receiving end 22 to outlet end 26 and a width of approximately 6.5 inches (16.51 cm) at receiving end 22.
and the width at the bottom wall 28 of the outlet end 26 was approximately 4 inches (10.16 cm). The melt of Type 304 alloy is tapped at 1580°C, fed into vessel 18, and maintained at a level of approximately 175 inches (4.445 cm) deep at receiving end 22, with the molten metal flowing into vessel 1.
The depth in the U-shaped structure of the outlet end 26 of the 8 was approximately 0.75 inches (0.905 cm). The casting surface is 7
It was a cast copper wheel having a diameter of approximately 36 inches (91.44 cm) with a depth of 1.5 inches (17.78 cm) and a cooling rate of less than 2000° C./sec. The casting wheel is spaced behind the outlet end of the vessel 18 at an angle of about 40 degrees and spaced about 40 mils (0.127 cm) from the outlet end at a rate of about 250 ft/min to 300 ft/min (76.2 m/min to 91.44 m/min). m/min). The U-shaped structure of the container had a flared or tapered inner surface 31 of the side wall 30 of the outlet end 26 that was open upwardly. The taper is approximately 3° on each inner surface. Approximately 100 bonds (45.359Kg) according to the present invention
molten metal 25 having a width of approximately 4 inches (10.16 cm) and a uniform thickness of 16 mils to 18 mils (0.04064 cm to 0.04572 cm);
It was possible to produce strips with smooth and uniform as-cast top and bottom surfaces and flat edges showing no evidence of roughness or curl. EXAMPLE A casting container having the overall structure shown in FIG. 4 and having a Kaoh wool refractory/alumina foam refractory insulation material 40 inside a metal cylinder 38 was constructed. The liner 42 was lined at 8 bonds/cubic foot (128.15 Kg/ft) with fiber flak material saturated with dilute colloidal silica suspension and then dried prior to use.
m ³ ) and 0.5 inch (1.27 cm) thick. The exterior dimensions of container 18 were approximately 15 inches (38.1 cm) long and 18 inches (45.72 cm) wide at the outlet end, increasing slightly in cross-sectional area to outlet end 26. The dam plate 36 was made and positioned in the same manner as in the example, and was joined between the side walls of the container 18. side wall 3
The inner surface 31 of each 0 was tapered by about 3 degrees and widened at the end. Place the casting vessel approximately on the free surface of the molten metal near the top of the casting wheel.
The spacing was approximately 35 mils (0.0889 cm) at a 0° angle. In accordance with the present invention, a 500 pound run 84-97 of type 304 molten metal with an outside diameter of 12.75 inches (32.35 cm),
It was cast on a 0.375 inch (0.9525 cm) wall thick and 48 inch (121.92 cm) wide low carbon steel seamless tube casting surface and internally water spray cooled.
Approximately 200FPM (60.96
m/min) for 10 to 15 seconds to facilitate flushing of the initial flow, then for a period of
The speed was reduced to 100FPM (30.48m/min). The molten metal was maintained at a depth of approximately 2 inches (5.08 cm) at the outlet end 26 and 2.75 inches (6.98 cm) at the receiving end 22. As-cast strips are approximately 13 inches (33.02 cm) wide
It had a uniform thickness of about 45 mils (114.3 cm) and a uniform, smooth, crack-free, good top surface quality. The as-cast strip is then soaked in nitric acid/
Pickled with hypofluorous acid, cold rolled to about 50% reduction, annealed at 1950° for 5 minutes, pickled again in the same manner, then cold rolled to 5 mils (0.0127 cm). It was sometimes treated using conventional methods and annealed. The room temperature mechanical properties of the as-annealed as-cast samples are shown below in comparison to typical properties of Type 304 annealed hot rolled bands manufactured using conventional methods.

[Table] Tensile strength of type 304 alloy manufactured by conventional method
It has typical or average room temperature mechanical properties of an annealed hot rolled band of 101.1 KSI, yield strength 43.8 KSI and 57% elongation at 2 inches (5.08 cm). FIG. 7 is a photomicrograph of an as-cast strip of the present invention showing representative internal structure from runs 8-52. Type 304 alloy is shown at 100x magnification and shows a typical as-cast texture of small cylindrical cells oriented in the direction of the thickness of the strip, ie, from top to bottom. This direction approximately corresponds to the direction in which heat is removed from the strip when it solidifies. The method and apparatus of the present invention can control the growth of dendrite structures in the strips to produce finished strips with properties comparable to or better than conventionally produced strip products. Manufacture as-cast strips. Figure 8 shows a typical structure of a conventionally produced hot rolled band of type 304 alloy at 100x magnification. In the method and apparatus of the present invention, as the size of the strip product increases and the width of the strip increases,
It can be seen that the structure and quality of the strips are uniformly good. 4 inches to 6 inches (10.16cm)
Edge curl tendency for strip products cast in widths of 13 inches (33.02 cm)
It seems that it no longer exists in such a wide range.
The method and apparatus of the present invention provides a simple, direct method for casting continuous strips of crystalline metal strips or sheets from molten metal. The problems of solidification shrinkage and cracking of finite strips are eliminated and relatively thick strips of quality comparable to or better than conventional manufacturing methods are obtained. The method and apparatus are useful with a variety of metals and alloys, including stainless steel and silicon steel.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the strip casting apparatus of the present invention; FIG. 2 is a cross-sectional elevational view of the casting vessel of the present invention;
Figure 2a is a detailed elevational view of Figure 2; Figure 2b is a detailed elevation view of Figure 2;
Further details of the Figures; Figure 3 is a plan view of the casting vessel of Figure 2; Figure 3a is an end view of the casting vessel of Figure 3; Figure 4 is a cross section of a preferred embodiment of the casting vessel of the present invention. 5 is a plan view of a preferred embodiment of the casting vessel of FIG. 4; FIG. 6 is a photomicrograph of an as-cast strip of type 304 alloy representative of the present invention; FIG.
The figure is a photomicrograph of a typical hot-rolled band made from Type 304 alloy using a conventional method. 10...Casting device, 12...Transfer container, 14...
...Supply tundish, 16... Hot water stop rod, 18...
...Casting container, 19... Molten metal, 20... Casting surface, 2
2...Receiving end portion, 24...Middle portion, 26...
Outlet end, 28...bottom wall part, 30...side wall part,
32...Tapered bottom wall, 36...Weir portion, 38...Outer cylinder, 40...Fireproof insulation material, 42...Liner.

Claims (1)

Claims: 1. A method for directly casting molten metal into a continuous strip of crystalline metal, comprising: a receiving end; and an exit end having an edge disposed adjacent to and parallel to the casting surface. supplying the molten metal to the receiving end of the casting vessel having the following steps; moving the cooling casting surface substantially upward past the outlet end; supplying the molten metal from the receiving end to the outlet end; providing a pool of molten metal having a substantially uniform flow and a free top surface at an exit end; and supplying molten metal from the exit end to a moving casting surface in a substantially uniform flow across the width of the exit end. The process and the depth of the molten metal at the outlet end of the casting vessel and the distance between the outlet end and the casting surface are controlled to reduce the surface tension acting on the top, bottom and sides of the molten metal at the outlet end of the casting vessel. and removing the casting strip from the moving casting surface. 2. The step of supplying the molten metal from the receiving end to the outlet end is such that the outlet end portion having a constant length in the direction of flow of the molten metal has uniform width and height over its length. 2. A method as claimed in claim 1, including maintaining a substantially uniform flow cross-sectional area in the outlet end portion by having the flow cross-sectional area of the outlet end portion substantially uniform. 3. A method according to claim 1, characterized in that the step of supplying the molten metal in the casting vessel includes the step of making the level of the molten metal at the receiving end the same as at the outlet end. 4. The supply of molten metal includes the step of gradually widening the width of the flow while maintaining a substantially uniform cross-sectional area of the flow from the receiving end to the outlet end. The method described in section. 5. By using a weir before the exit end,
2. A method as claimed in claim 1, including the step of attenuating the flow of molten metal in the casting vessel to facilitate the formation of a uniform flow at the exit end. 6. The step of moving the casting surface from the bottom of the generally U-shaped structure towards the top of the outlet end and past the generally U-shaped structure at the outlet end of the container. A method according to claim 1. 7. The casting surface, measured along the path from the horizontal plane, between the free surface of the molten metal at the outlet end of the casting container and the direction of the casting surface at the outlet end, is approximately 0° to
A method according to claim 1, characterized in that it comprises the step of moving in the direction of metal flow at an angle of 135°. 8. The method of claim 7, wherein the angle is between 0° and 45° from the horizontal plane. 9. A method as claimed in claim 1, including the step of adjusting the thickness of the strip by the speed of the casting surface and the depth of the melt at the outlet end of the casting vessel. 10 After bringing the molten metal into contact with the casting surface, heat it to 2000℃/
Claim 1, characterized in that it includes a step of solidifying the crystalline metal by cooling at a rate of less than a second.
The method described in section. 11. A method according to claim 10, characterized in that the cooling is carried out at a rate of less than 1500° C./sec. 12. The method of claim 1, wherein the casting surface moves at a speed of 20 ft/min to 500 ft/min (6.096 m/min to 152.4 m/min). 13 Place the casting surface 0.005 inch or more from the outlet end.
2. The method of claim 1, wherein the method is parallel to the edge of the outlet end at a distance of 0.060 inches. 14 4 inches to 48 inches (10.16 cm to
A method as claimed in claim 1, characterized by the step of removing from the casting surface a strip having a uniform strip width within the range of 121.92 cm). 15 The removed strip is 0.010 inch to
The method of claim 1, having a uniform thickness within the range of 0.100 inches (0.0254 cm). 16 Apparatus for directly casting molten metal into a continuous strip of crystalline metal, comprising: a casting vessel having a movable casting surface; a receiving end, an outlet end and an intermediate portion therebetween; an outlet end having a generally U-shaped structure adjacent the casting surface with edges parallel to the casting surface; the U-shaped structure at the outlet end has a flat bottom wall and an upwardly open divergent inner wall; and has approximately the same width as the strip to be cast between the inner surfaces of the sidewalls, and the outlet end has a constant width along the bottom wall between the inner surfaces of the sidewalls and approximately the same width as the strip to be cast between the inner surfaces of the sidewalls and approximately the same width as the strip to be cast between the inner surfaces of the sidewalls. the casting surface has a uniform cross-sectional area over a length sufficient to provide uniform flow, and the casting surface is approximately 0.005 inches from the exit end
approximately upwardly past the outlet end of the casting vessel at a distance of 0.060 inch (0.0127 cm to 0.1524 cm) and at a speed of 20 ft/min to 500 ft/min (0.096 m/min to 152.4 m/min). can move,
A device characterized by: 17. The device according to claim 16, wherein the molten metal level at the receiving end and the molten metal level at the outlet end are the same. 18 The intermediate portion communicating the receiving end and the outlet end has a width that gradually increases towards the outlet end and a gradually increasing width towards the outlet end so as to maintain a uniform cross-sectional area over the length of the casting vessel. 17. Device according to claim 16, characterized in that it has a decreasing depth. 19. Apparatus according to claim 16, characterized in that it has a baffle in the casting vessel to facilitate the formation of a uniform flow. 20 The casting surface has a direction of motion upward from the horizontal plane, and the direction of metal flow on the free surface of the molten metal at the outlet end is the same as the direction of the free surface at the outlet end and the casting surface at the outlet end. 17. The device of claim 16, wherein the device is oriented at an angle of about 0° to 135° from the horizontal plane, measured between. 21. Apparatus according to claim 20, characterized in that the outlet end of the container is adjacent to the casting wheel at a position forming an angle of 0° to 45°. 22. Apparatus according to claim 16, characterized in that the casting surface consists of the circumferential surface of a rotary casting wheel. 23. Apparatus according to claim 22, characterized in that the outlet end of the casting vessel is adjacent a location in the upper quadrant of the casting wheel. 24. supplying molten metal to a receiving end of a casting vessel having a receiving end and an outlet end disposed adjacent to and in equilibrium with a casting surface; a step of moving the molten metal substantially upward past the end; and supplying the molten metal from the receiving end to the outlet end.
providing a pool of molten metal with a substantially uniform flow and a free top surface at the exit end; and directing the molten metal from the exit end to a moving casting surface with a substantially uniform flow across the width of the exit end. controlling the depth of the molten metal at the outlet end of the casting vessel and the distance between the outlet end and the casting surface to act on the top, bottom and sides of the molten metal at the outlet end of the casting vessel; A continuous strip of crystalline metal produced by a method of direct casting of molten metal into a continuous strip of crystalline metal comprising the steps of maintaining surface tension and removing the cast strip from a moving casting surface. 25. The strip according to claim 24, having a uniform casting thickness of 0.010 inch to 0.0100 inch (0.0254 cm to 0.254 cm), and having both sides uniform and smooth. . 26. A strip according to claim 24, characterized in that it has an internal organization of relatively small cylindrical cells oriented in the direction from one surface to the other. 27. A strip according to claim 24, characterized in that it has substantially flat and smooth edges. 28 0.002 inch to 0.040 inch (0.00508 cm to 0.00508 cm) with pickling, annealing, and intermediate annealing
0.1016 cm) and then conventionally annealed to have mechanical properties comparable to or superior to conventionally manufactured strip products. A strip according to claim 24. 29. A continuous strip of crystalline metal cast directly from the molten metal onto a single moving casting surface, comprising an upper surface and a lower surface in contact with the casting surface, the upper and lower surfaces in the as-cast condition being: Smooth and uniform, the edges of the strip are substantially flat and uniform, the as-cast thickness is in the range of 0.010 inch to 0.100 inch (0.0254 cm to 0.254 cm), and the internal texture of the strip is A strip characterized in that it has relatively small cylindrical cells oriented in the direction from one surface to the other. 30 0.002 inch to 0.040 inch (0.00508 cm to 0.00508 cm) with pickling, annealing, and intermediate annealing
Claim 29 characterized in that when cold rolled to a final dimension of 0.106 cm) and then annealed, the strip has mechanical properties that are at least comparable to conventionally produced strip products. Strip as described in .