CN108883462A - Liquid metal jet optimization in direct-chill casting - Google Patents

Abstract

A kind of liquid metal jet of molten metal feed during direct-chill casting operation can be optimized to which the rate to be equal to casting speed corrodes the slurry area of fusant storage tank rather than frozen metal.It can make the model nondimensionalization of the corrosion of the solidification crystal grain in the slurry area of the fusant storage tank, the casting parameter (for example, the nozzle opening of optimal size and optimal molten metal flowing rate) of the liquid metal jet of the optimization will be provided during casting process for generating.A kind of ingot casting that the liquid metal jet using this type of optimization is cast will have improved gross segregation characteristic (such as, reduced gross segregation or the gross segregation being more evenly distributed), for example, on the width of the ingot casting or height from molten metal source of supply concentration variation about 10% or smaller or 5% or smaller ingot casting solute concentration.

Description

Optimization of Liquid Metal Jet Flow in Direct Chill Casting

Cross References to Related Applications

This application claims the benefit of U.S. Provisional Patent Application No. 62/313,493, filed March 25, 2016, and entitled LIQUID METAL JET OPTIMIZATION IN DIRECT CHILL CASTING, Said application is incorporated herein by reference in its entirety.

technical field

The present disclosure relates generally to metal casting, and more particularly to controlling the introduction of liquid metal into a molten metal sump during direct chill casting.

Background technique

In the metal casting process, molten metal is conveyed into a mold cavity. For some types of casting, mold cavities with false or shifted bottoms are used. As the molten metal enters the cavity substantially from the top, the false bottom decreases at a rate related to the flow rate of the molten metal. Molten metal that has solidified on the side can be used to retain liquid and partially liquid metal in the melt sump. Metals can be 99.9% solid (eg, all solid), 100% liquid, and anything in between. Because the thickness of the solid region increases as the molten metal cools, the melt sump can be V-shaped or U-shaped. The interface between solid and liquid metal may be called the solidification interface.

When the molten metal in the melt sump varies between about 0% solids to about 5% solids, nucleation can occur and small metal crystals can form (e.g., endogenous, e.g., from homogeneous nucleation or from dendritic crystal fragmentation, or exogenously, e.g. by addition of grain refiners). As the molten metal cools, these small (eg, nanometer to micrometer sized) crystals begin to nucleate and form dendrites. When the molten metal cools to the dendrite coherence point (for example, 632°C for 5182 aluminum used in beverage can ends), the dendrites begin to stick together to form an interconnected network. Between the melting temperature and the coherent temperature, these crystals are mobile and may be susceptible to hydrodynamic drag and gravity, which may cause these crystals to accumulate in the bottom of the tank. Due to the limitations of the industrial solidification process, complete diffusion does not occur, resulting in depletion of individual grains in the solute. When these individual grains accumulate, the overall effect can greatly alter the local composition within the cast product, which can cause changes in the properties of the cast product. Also, depending on the temperature and percent solids of the molten metal, the crystals can contain or trap different particles, such as particles of FeAl ₆ , Mg ₂ Si, FeAl ₃ and Al ₈ Mg ₅ in certain aluminum feedstocks; or impurities such as H ₂ bubbles.

In addition, as the crystals solidify and subsequently cool, additional solute material (e.g., alloying elements) can be drawn between the crystals (e.g., between dendrites of the crystals) and can accumulate in the melt sump, typically At intermediate thicknesses, this results in an imbalance of alloying elements within the ingot. Separation of alloying elements on a macroscopic scale can be referred to as macrosegregation. When analyzing ingots or semi-finished products, macrosegregation can be seen as variations in the composition of the cast ingot over the dimensions (eg, width, length, height, or diameter) of the cast product. Macrosegregation of cast ingots can lead to waste and increased costs. Macrosegregation can further lead to weakened ingots or semi-finished products, which may be particularly undesirable for certain applications such as aerospace frames.

For various measurable quantities, such as components, the ingot may need to fall within certain desired specifications. These quantities can be adversely affected by undesirable macrosegregation. While ingots with undesired macrosegregation overall may have measurable amounts that fall within desired specifications, individual regions of the ingot, especially those regions with higher levels of macrosegregation, may have measurable amounts that fall within desired specifications. A measurable quantity outside the required specification. For example, an ingot may have a composition that varies by about 25% or more over the dimension of the ingot. In such instances, the ingot as a whole may result in a measurable amount that falls within the desired specification of the ingot, but the amount of macrosegregation near the center of the ingot may be substantially stronger such that the central region of the ingot has far greater A measurable quantity that falls outside the required specification. Thus, various specifications of products made using such standard ingots may require large safety margins (e.g., in At any given point, the average material strength far exceeds the expected load on the material).

Attempts to reduce undesirable macrosegregation in cast products have relied on the use of excess grain refiners, which may be undesirable for a variety of reasons including cost and the risk of ingot contamination. In some cases, attempts to reduce undesirable macrosegregation in cast products have relied on the use of physical barriers to slow or reduce fluid flow within liquid sumps.

Description of drawings

The specification refers to the following drawings, wherein the use of like reference numerals in different drawings is intended to illustrate like or analogous components.

FIG. 1 is a partial cross-sectional view of an example metal casting system for supplying a jet of liquid metal.

Figure 2 is a schematic representation of a jet of liquid metal impinging on the slurry zone of a molten metal sump.

3 is a graph depicting predicted dimensionless jet processing parameters for various example aluminum alloys designed to provide crystallinity in the slurry region of the metal storage tank, according to certain aspects of the present disclosure. Optimal Liquid Metal Jet for Particle Resuspension.

4 is a contour plot depicting macrosegregation intensity according to vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast using the prior art without the liquid metal jet optimization techniques disclosed herein.

5 is a graph depicting the vertical flow in an aluminum alloy Al4.5Cu ingot cast using parameters set to achieve a mold Reynolds number (Reynolds number) of approximately 1600 and a nozzle opening selected to achieve a jet Reynolds number of approximately 64000. Contour plots of macrosegregation intensities at and horizontal positions.

6 is a graph depicting the vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast using parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 69000. Contour plot of macrosegregation intensity.

7 is a graph depicting the vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast using parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 81000. Contour plot of macrosegregation intensity.

8 is a graph depicting the vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast using parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 97000. Contour plot of macrosegregation intensity.

9 is a graph depicting vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast using parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 121000 Contour plot of macrosegregation intensity = .

10 is a graph depicting Macrosegregation Index (MI) as a function of jet Reynolds number for each of the ingots of FIGS. 5 to 9 .

11 is a flowchart depicting a process for determining optimal casting parameters based on known molds, according to certain aspects of the present disclosure.

Detailed ways

Certain aspects and features of the present disclosure relate to optimization of liquid metal jets for supplying molten metal during direct chill (DC) casting operations. Erosion of solidified grains in the slurry zone of the melt tank can be modeled to determine an optimized liquid metal jet that can be used to corrode the slurry zone of the melt tank rather than the solidified metal at a rate equal to the casting velocity. The dimensionless form of the model can be used to generate casting parameters (e.g., optimally sized nozzle openings and optimal molten metal flow rates) that will provide optimized liquid metal jets during the casting process, resulting in metal ingots with improved macroscopic Segregation properties (eg, reduced or nearly eliminated macrosegregation, more evenly distributed solute, or more uniform macrosegregation distribution). Ingots cast using the optimized liquid metal jet casting described herein can have low macrosegregation, where the solute concentration varies by about 10% or less or 5% from the molten metal supply concentration across the width, length or height of the ingot or smaller.

Macrosegregation may occur due to the relative motion of the liquid and solid phases during solidification. Microscale partitioning of solutes between liquid and solid phases (eg, microsegregation) can translate into larger scale differences in chemical composition (eg, macrosegregation). This relative motion can be driven by various factors, the magnitude of which can depend not only on casting practice, but also on the alloy composition and shape of the transition zone. Various factors such as temperature convection and constricted flow in the smelt storage tank can be difficult to control. In some cases, macrosegregation may occur due to one or more of a combination of constricted flow as grains form and grain deposition at the bottom of the liquid sump. In relatively large ingots and billets (e.g., having a diameter or thickness equal to or greater than about 300 mm), grain deposition becomes the dominant factor for macrosegregation, whereas in relatively small ingots and billets (e.g., having Below about 300 mm in diameter or thickness), constricted flow becomes the dominant factor in macrosegregation. Constricted flow can cause inhomogeneity in the distribution of solutes in the liquid sump. Certain aspects and features of the present disclosure relate to techniques for improving macrosegregation by counteracting certain macrosegregation-inducing effects of constriction flow and/or grain deposition.

Commercially cast aluminum alloys may tend to solidify into equiaxed grains, often due to the addition of exogenous nucleation sites (eg, grain refiners). In the slurry region between the liquidus and the coherent isotherm, the solidified grains may be mobile and may move short distances depending on the conditions of the melt tank (e.g., temperature convection, constricted flow, and volume change in contact with aluminum). or long distances. When the freely moving grains migrate and settle to the bottom of the tank, a fraction of the solid phase greater than that at the target equilibrium conditions can be obtained. These grains that settle to the bottom of the tank may be referred to as grain deposits. In hypoeutectic aluminum alloys comprising many, if not most, DC casting products, the solid phase can be less solute-rich than the liquid state, resulting in more solid phases with negative segregation (e.g., lower solute concentration than that of the molten metal supply source average solute concentration). In an example, the concentration of solute at the centerline of the DC cast ingot may be about 15% to 20% lower than the concentration of the furnace composition of the molten metal used to cast the ingot.

Negative segregation can significantly alter the final mechanical properties of cast ingots or semi-finished products (eg, ingot or semi-finished castings of 1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, 7xxx, and 8xxx series aluminum alloys). Preventing the preferential deposition of freely moving grains can alter the macrosegregation, ultimately reducing the variation in the composition of the DC cast ingot over the ingot size. Jets of molten metal can be introduced directly into the bottom of the tank to prevent grain deposition. In some cases, such as billet (e.g., round extruded or forged ingot) casting, etc., the introduction of certain jets into the bottom of the tank can cause corrosion of the tank itself (e.g., of fully solidified metal), which May cause problems and adversely affect the solidification of the ingot. For example, in billet casting, the ideal diameter jets can have a very narrow range, with jets of too small diameter producing undesirably deep holes in sump with undesirably steep sump profiles, and jets of too large diameter The jets create undesirably wide holes in sumps with undesirably wide sump profiles. Certain aspects of the present disclosure relate to optimizing a molten metal jet with sufficient power to suspend a deposit of grains without causing corrosion of the sump. In some cases, aspects of the present disclosure are used with DC casting of rectangular ingots. In some cases, aspects of the present disclosure are used with vertical casting. In some cases, aspects of the present disclosure occur at or within 30°, 25°, 20°, 15°, or 10° from vertical. used together with casting. In some cases, aspects of the present disclosure are used with horizontal casting.

Optimized casting parameters (eg, metal flow rate and/or nozzle opening diameter) can produce a jet of liquid metal sufficient to remove excess grains from the slurry region of the sump while allowing some grains to settle and fully solidify. This jet can counteract the effects of grain deposition and potentially some of the effects of constricted flow. The optimal energy of a liquid metal jet can fall within a narrow range defined by the dimensionless Reynolds number of the jet. Optimized casting parameters can be determined such that the resulting dimensionless Reynolds number of the jet and the resulting dimensionless Reynolds number of the mold fall within the range of predicted values based on the techniques disclosed herein.

In addition to or as an alternative to grain deposition, constricting flow can cause macrosegregation problems. For example, a solidified grain may cause a localized increase in solute concentration in the liquid metal immediately adjacent to the solidified grain, while the solute concentration in portions of the liquid sump remote from the solidified grain remains relatively low. As the grains solidify, solutes can become encapsulated within or between grains. Since the solute concentration of the liquid adjacent to the solidified grains tends to be relatively high, this solute coating can lead to undesirable intermetallic compounds. These high solute concentration clad regions may be the result of constricted flow.

In some cases, optimizing the casting parameters can produce a liquid metal jet sufficient to optimize or increase the uniformity of solute distribution within the liquid metal storage tank. Such jets can counteract the effects of constricted flow and potentially some of the effects of grain deposition. Sufficient jets of liquid metal can be directed into the liquid sump and can induce sufficient liquid motion within the sump to mix localized regions of relatively high solute concentration with localized regions of relatively low solute concentration, resulting in an overall more uniform liquid metal storage tank. Thus, when a sufficient jet of liquid metal is used, the concentration of any coated solutes can be relatively lower than when no jet of liquid metal is used (eg, when a combination bag or filter bag is used).

Additionally, sufficient liquid metal jets reduce porosity due to the presence of hydrogen in the liquid metal. Under standard casting conditions, hydrogen gas can be packed between the dendrite arms. However, when sufficient liquid metal jets are provided, the resulting liquid motion within the liquid metal sump can promote the coalescence of hydrogen bubbles, making it easier for the hydrogen bubbles to float to the top of the sump and be released from the liquid metal. In some cases, at least some of the hydrogen gas expelled adjacent to the solidified grains may be mixed within the liquid metal rather than being trapped between dendrites.

Accordingly, certain aspects and features of the present disclosure may improve macrosegregation by counteracting certain macrosegregation-inducing effects of constriction flow and/or grain deposition. The resulting metal ingots or ingots may have improved macrosegregation characteristics over metal ingots or ingots formed without the use of certain aspects and features of the present disclosure. As described herein, improved macrosegregation properties can be represented by a macrosegregation index, where higher numbers indicate increased undesirable macrosegregation within the ingot or billet. Improved macrosegregation properties may have a macrosegregation index that is lower than that of an ingot cast without using certain aspects and features of the present disclosure.

To model the DC casting process, it can be assumed that heterogeneous nucleation acts as the sole source of grains at the solidification interface. Therefore, mass conservation can provide a governing migration equation in the slurry region, as shown in Equation 1. Equation 1 can be based on a simplified version of the Euler transfer equation, where N is the source term for nucleation (e.g., in m ⁻³ s ⁻¹ ), and n is the number density of grains (e.g., in m ⁻³ s −1 in units), and u _t is the velocity of the moving liquid metal (eg, in meters per second).

A statistical model of grain density as a function of average undercooling (ΔT _N ±ΔT _σ ) and maximum grain density (n _max ) can be determined using a Gaussian distribution as shown in Equation 2, where ΔT _N is the average undercooling , ΔT _σ is the standard deviation of supercooling and ΔT is the amount of supercooling.

Certain parameters of Equation 2 (eg, the subcooling term) can be determined experimentally for a given alloy composition, type of grain refiner used, and duration of grain refiner addition. Each unique subcooling may correspond to a certain nucleation radius given, for example, by the Gibbs-Thomson relationship.

Nucleation and melting in Equation 1 can be contained in a single source term N related to the total grain density n(ΔT) at a given given supercooling ΔT via the integration of Equation 2, as in Equation 3 Shown:

There are additional conditions in the steady-state grain density (e.g., in Equation 1 ). Therefore, the primary transport equation can be defined by equating the advection contribution with the nucleation at the interface, taking into account the local subcooling. The application of equations of this form as boundary conditions at the solidification interface can be implemented as a finite element code to determine appropriate jet parameters. This approach may provide an accurate solution, but may be computationally expensive (eg, in terms of computation time, energy cost, and capital cost). Therefore, it is desirable to present problems in a dimensionless form that can be used quickly by practitioners without significant computational expense.

Modeling grain flow, and in particular grain corrosion, on particle surfaces can begin by characterizing the suspension and migration of particles in a statistically stable turbulent flow over the particle bed by the shielding parameter Sh. The shielding parameter can represent the ratio of the shear stress due to fluid flow relative to the weight per unit area of individual grains within the bed, as shown in Equation 4, where U is the characteristic flow velocity, dg is the grain diameter, and g is due to gravity induced acceleration (eg, during vertical DC casting), and ρf and ρg are the fluid and grain densities, respectively.

If the shielding parameters exceed critical values, grain migration can occur, which can depend on grain size, shape, cohesion, and buoyancy. This critical shielding parameter can be difficult to determine experimentally, in part because the physical mechanism of resuspension occurs temporarily due to turbulent fluctuations.

An alternative classification of particle resuspension and sedimentation can be expressed by the Rouse number (Rs), which is proportional to the ratio of the sedimentation velocity of the grains to the turbulent shear velocity of the bed. This relationship is expressed in Equation 5 below, where u _* is the shear rate, κ is a von Kármán constant (eg, about 0.40 or 0.41), and Us is the terminal sedimentation _velocity of the grains.

Below the critical value of Rs, the flow may be able to maintain the grains in suspension because the turbulent velocity fluctuations are greater than the terminal velocity of each grain. In unidirectional steady flow, sufficient bed migration is expected to be Rs ≤ 2.5, and if Rs ≤ 1, significant resuspension occurs. Unlike the screening number, the Rouse number can account for the effect of viscosity on each particle through its respective value of sedimentation velocity U _s . For very small grains (e.g., about 70 μm or less in diameter in aluminum systems), U _s gives the settling velocity U _s by Stokes, as shown in Equation 6, where υ is the dynamic viscosity (e.g. , molten aluminum is about 5.5×10 ^-7 m ² /s).

The particle Reynolds number (Reg _{) can then be most effectively defined using Us as the characteristic velocity, as shown in Equation 7, where dg is the} grain diameter.

The above parameters have been determined experimentally for horizontal flow through a horizontal bed of particles, as described herein. However, for a jet impinging vertically on a particle bed, the counterparts of the defined parameters can be redefined, as described in further detail below with reference to FIG. 2 . Thus, a dimensionless model can be generated that can be used to optimize casting parameters to ensure that there is an optimized liquid metal jet that minimizes the intensity of macrosegregation in the cast ingot.

Minimizing the intensity of macrosegregation in cast ingots can lead to immediate benefits (e.g., more industrially desirable ingots or more consistent ingot formation), as well as other benefits such as reduced grain size, Improved dendrite formation and reduced need for grain refiners. In some cases, desired cast ingots can be produced with little or no added grain refiner. In addition, an optimized liquid metal jet can break up the grains, which can promote the expansion of smaller sized grains throughout the cast product, which can be desirable. For example, optimized liquid metal jets can be used to produce spherical grains using otherwise standard DC casting.

In some cases, optimized liquid metal jets can help degas molten metal. For example, hydrogen gas dissolved in liquid aluminum can be washed away by agitation provided by optimized liquid metal jets at the slurry zone of the melt storage tank. Due to the limited solubility of hydrogen in solid aluminum, small amounts of hydrogen containing insufficient amounts to nucleate gas bubbles can be stirred and washed towards the surface by a jet of liquid metal. Hydrogen that has been scrubbed to the surface can be removed as an impurity. Additionally, in some cases, tailoring the nozzle size or flow rate as disclosed herein can be used to alter the morphology or distribution of the second phase particles. Additionally, in some cases, custom nozzle sizes or flow rates as disclosed herein can be used to provide improved mixing, for example by providing additional molten metal into solute-rich regions (e.g., adjacent to the solidification front) to dilute those area.

These illustrative examples are given to introduce the reader to the general subject matter discussed herein, and are not intended to limit the scope of the concepts disclosed. The following sections describe various additional features and examples with reference to the drawings, wherein like numerals indicate like elements, and directional descriptions are used to describe illustrative embodiments, but like illustrative embodiments, should not be used to limit the present disclosure. Elements contained in the descriptions herein may not be drawn to scale.

FIG. 1 is a partial cross-sectional view of a metal casting system 100 for supplying a liquid metal jet 134 . Metal source 102 , such as a sprue cup, may supply molten metal down feed tube 136 and out nozzle 110 . The bottom block 122 may be lifted by hydraulic cylinders 124 to interface with the walls of the mold cavity 116 . The bottom block 122 may be lowered steadily as the molten metal begins to solidify within the mold. The cast metal 106 may include solidified sides 120 , and molten metal added to the cast may be used to continuously elongate the cast metal 106 . In some cases, the walls of mold cavity 116 define a hollow space and may contain coolant 118, such as water. The coolant 118 may exit the hollow space as a jet and flow down the side 120 of the cast metal 106 to help solidify the cast metal 106 . The cast ingot may contain a solidified metal region 130 , a transition metal region 128 , and a molten metal region 126 .

The nozzle 110 through which molten metal is supplied to the melt sump 112 may be positioned below the surface 114 of the melt sump 112, at least during steady state operation (e.g., after starting the casting process but before completing the casting process) . The nozzle 110 may be shaped to have an opening 108 (eg, an outlet) sized to produce an optimized liquid metal jet 134 into the melt sump 112 . In some cases, nozzle 110 may include multiple openings designed to produce one or more jets of liquid metal. The liquid metal jet 134 exiting the nozzle 110 may be turbulent or laminar. An optimized liquid metal jet 134 may be optimized to impinge into the slurry region of the metal sump 112, such as the portion of the transition region 128 near the center of the cast ingot, with sufficient jet flow to resuspend any deposits therein Sufficient force of the grains, but not an amount of force that would corrode the bottom of the melt sump 112 (eg, solidification zone 130 ).

In some cases, optional flow control device 104 is operatively coupled to nozzle 110 to provide control over the flow of molten metal exiting nozzle 110 . In some cases, flow control device 104 is a flow reducing device capable of reducing the flow of molten metal from feed tube 136 . An example of a suitable flow reducing device is a control pin located within feed tube 136 . In some cases, flow control device 104 may be a flow booster device capable of increasing the flow of molten metal from feed tube 136 . An example of a suitable flow enhancing device may be a metal pump, such as the non-contact molten metal pump described in US Application Serial No. 14/719,050, filed May 21, 2015, which is incorporated by reference in its entirety. In some cases, the flow enhancer may also act as a flow reducer.

Flow control device 104 may be controlled by controller 132 to regulate the flow rate of molten metal exiting nozzle 110 . In some cases, controller 132 may be coupled to one or more sensors for sensing parameters of metal casting system 100 that may be used by controller 132 to estimate or calculate the depth of metal storage tank 112 . Examples of suitable sensors include distance sensors (eg, laser, ultrasonic, or other), temperature sensors, or other sensors.

When the flow control device 104 is used, control of the flow of molten metal through the nozzle 110 by the flow control device 104 can be used, along with knowledge of the size of the nozzle 110 and/or the characteristics of the cavity 116, to provide the molten metal for the melt sump 112. Optimized liquid metal jet 134 . Controller 132 may adjust one or more flow control devices 104 , such as pumps and/or control pins, to regulate the flow of metal through nozzle 110 . In some cases, the controller 132 may monitor the casting process to determine the casting rate or the estimated depth of the metal sump 112 to adjust the flow of molten metal through the nozzle 110 via the flow control device 104 to optimize the liquid metal jet 134 exiting the nozzle 110 .

In some cases, the flow control device 104 is used to slow down the flow rate of molten metal through the nozzle 110 at least during the initial stage of casting (eg, the first 100-300mm of casting), so that the flow rate of molten metal can follow the casting speed. Rise slowly from zero to full speed.

In some cases, controller 132 may control one or more flow control devices 104 to regulate the flow of metal through nozzle 110 in an oscillatory mode. The oscillatory pattern may involve increasing and decreasing metal flow through the nozzle 110 over time, which may further facilitate counteracting factors that cause macrosegregation, such as grain deposition and/or solute inhomogeneity.

FIG. 2 is a schematic representation 200 of a liquid metal jet 234 impinging on the slurry region 228 of the molten metal sump 212 . For example, liquid metal jet 234 may be liquid metal stream 134 impinging on transition region 128 of metal sump 112 of FIG. 1 . The liquid metal jet 234 may have a diameter of The volume flux Q ₀ of the molten metal injected by the nozzle 210 of the opening 208 onto the particle bed 236 , where The velocity of jet 234 exiting nozzle 210 may be denoted by U ₀ . Jet 234 may be located at height H ₀ above coherence isotherm 238 . In the case of DC casting, H ₀ may be estimated based on the sump depth 244 since the slurry region may be difficult to detect. Various relationships can be used to estimate sump depth as a function of casting parameters. A bed 236 of particles of material forming the slurry region 228 of the molten metal sump 212 may be positioned above a coherence isotherm 238 . The slurry region 228 may have a height h ₀ above the coherence isotherm 238 . Individual grains 242 in slurry region 228 may be defined to have a diameter d.

As described above, for a jet 234 impinging vertically on a bed of particles 236, Equation 5 representing the Rouse number for a turbulent jet impinging on the bed of particles in the horizontal domain can be redefined, as shown in FIG. A redefined equation for this vertical domain can be expressed by Equation 8, where _Uj is the velocity of the jet 234 at the surface of the particle bed 236 (e.g., at a distance H0- _h0 from the nozzle opening 208 ₎ , and k is von Kármán constant (eg, about 0.40 or 0.41), and U _s is the terminal sedimentation velocity of the grains 242 .

The velocity of the jet 234 at the surface of the particle bed 236 can be determined by applying the theory of turbulent jet flow as shown in Equation ₉ , where b0 is the radius of the nozzle opening 208 and H0 and _h0 represent the fluid ₍ e.g., molten metal) and particle bed 236, and U ₀ is the average of the fluid entering the melt sump at nozzle opening 208 as determined by Equation 10 (e.g., expressed as a function of volumetric flow rate Q ₀ ). speed.

For turbulent jets, an entrainment constant α of about 0.08 can be used.

For spherical particles following Stokes' law (eg, _Reg <.1), Sh, Rs, and _Reg can thus be related by Equation 11.

according to It can be seen that the critical shielding number Sh _c is related to the particle Reynolds number. Therefore, the critical Rouse number can be determined according to Equation 12 for scaling using the particle Reynolds number.

The presence of several grains descending together at a cluster velocity U _th is provided by Equation 13, where _Cv is the volume fraction of solid particles and m is a constant for the Reynolds number of the particles obtained by Equation 14.

U _th = U _s (1-C _v ) ^m (13)

Equation 5 from MGChu, JE Jacoby was used. "Macrosegregation characteristics of commercial size aluminum alloy ingot cast by the direct chill method". In: CM Pickert (ed.), Light Metals, TMS, PA, (1990), on the volume fraction of sedimentation grains, combined in Wagstaff, SR, Allanore, A. "Experimental observation and analysis of macrosegregation in rolled plate ingots ( Extent of centerline solute depletion as observed in Experimental Observations and Analysis of Macrosegregation in Rolling Slab Ingots), in: M. Hyland (ed.), Light Metals, TMS, PA, 2015, which reference is incorporated herein, Volume fraction of solid particles (C _v ) can be determined to be about 0.2. Applying this effect to Equation 11 yields Equation 15.

As described above, liquid metal jet 234 is capable of suspending grains 242 from particle bed 236 if a critical screening parameter Sh _c is exceeded or if the Rouse number is below Rs _c (eg, a critical Rouse number). For horizontal channel flows, bottom sand migration can be defined by the grain volume flux per unit flow width Q. Substrate transport is then normalized by grain size and settling velocity to obtain a dimensionless flux per unit width.

For substrate transport in uniform horizontal flow over a granular bed, an experimental relationship has been determined such that This is related to the difference Sh-Sh _c of Equation 16 below, where the values of P and C _s are constants that depend on the grain size, density, and stress imposed by the fluid in the bed. The constants P and C _s can be determined experimentally.

The radius of the dimple 240 created by the impinging jet 234 may not change significantly with increasing jet power. Thus, the dimple 240 may deepen as the jet velocity at the bottom of the dimple 240 increases, while maintaining a nearly constant radius (r ₀ ). Such assumptions and extrapolations are likely to be valid at least for uncohesive grains forming permeable beds. However, in addition to applied shear stress, cohesive particle beds (eg, welded grains) can also rely on high temperature creep effects for resuspension. Thus, the bed of cohesive particles may "reflect" at least a portion of the impinging jet and thus cause the jet to have a less uniform and predictable effect. Additionally, impingement behavior may induce surface pressure distribution and percolation within the bed. This percolation may allow shear stresses to act deep within the bed rather than dissipate quickly, as is the case with impermeable beds.

Thus, the volumetric flux of grains suspended from the dimple 240 due to the liquid metal jet 234 can be expressed according to Equation 17, assuming that the dimple descent velocity (U _c ) (e.g., the speed at which the dimple 240 deepens) is constant ( For example, also assume that the volumetric flux is constant). In other words, Equation 17 may represent the volumetric flux of grains displaced from the slurry zone 228 due to the impingement of the liquid metal jet 234 . The term r ₀ may denote the radius of the pit.

The grain flux per unit area density of the grain is available indicated that it uses the hindered settling velocity to explain the grain-to-grain interactions within the pits.

The grain flux per unit area density of grains can be used in dimensionless Equation 17, as shown in Equation 18, where is the dimensionless volumetric flux.

The relationship shown in Equation 18 defines the relative pit descent velocity, showing that the pits 240 descend independently of the properties of the die itself.

Since the definition of Rs in Equation 8 explicitly invokes the sedimentation velocity of the grain 242, and thus can account for the effect of turbulent fluctuations, Equation 16 can be replaced by the dimensionless flux of the grain as shown in Equation 19, where _Cr is a constant of proportionality that depends on the grain size, density, and stress exerted by the fluid in the bed. The constant C _r can be determined experimentally.

Thus, using Equations 8 and 18 and the relationship of the critical Rouse number from Equation 15, Equation 19 provides an explicit expression of the pit descent velocity _Uc as a function of the velocity of the jet 234 over the bed 326, as in Equation 20 , where _C1 and _C2 are constants of proportionality that depend on the grain size, density, and stress imposed by the fluid in the bed. The constants _C1 and _C2 can be determined experimentally.

To provide an optimal solidification environment, at least for the purpose of improving macrosegregation, it may be desirable to design a liquid metal jet 234 with a precise range sufficient to resuspend the settled grains 242 but insufficient to corrode the bottom of the sump 212 power within. Accordingly, the liquid metal jet 234 should be designed to induce a pit descent velocity (U _c ) approximately equal to the casting velocity (eg, the vertical displacement velocity of the solid ingot). Such criteria can ensure that there are no or few accumulated grains 242 in the center of the ingot, and that the power of the jet is dissipated in particle resuspension (eg, rather than eroding fully solidified metal). In some cases, the desired ingot may be cast using nozzles that provide sufficient to maintain, at least during steady casting, approximately equal to or no more than 1%, 2%, 3% slower than the casting rate. %, 4% or 5% of the pit drop speed of the liquid metal jet. In some cases, the desired ingot may be cast using nozzles that provide sufficient dimple drop rates to maintain a rate of about 1%, 2%, 3%, 4% from the casting rate, at least during steady state casting. %, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15% or less variation within the liquid metal jet.

Since the jet velocity (U _j ) at the particle bed surface can be defined as a function of the volumetric flow rate, and thus also of the casting velocity, an iterative computational solver can be implemented until convergence. The equations described above can be applied to determine optimal casting parameters, including nozzle opening and flow rate, as described herein.

3 is a graph 300 depicting predicted dimensionless fluidic processing parameters for various example aluminum alloys designed to provide a slurry zone for metal sump, according to certain aspects of the present disclosure. Optimal Liquid Metal Jet for Grain Resuspension. The mold Reynolds number (Re _m ) 304 may be based on equivalent hydraulic radii and casting speeds. Jet Reynolds number (Re _j ) 302 may be based on jet velocity and diameter. The shaded area 312 may represent a range of values depending on the properties of the alloy suitable for providing an optimal liquid metal jet to resuspend the grains in the slurry region of the metal sump. For example, line 306 may represent predicted dimensionless jet processing parameters for aluminum alloy 5182, line 308 may represent predicted dimensionless jet processing parameters for aluminum alloy Al4.5Cu, and line 310 may represent predicted dimensionless jet processing parameters for aluminum alloy 1050 Prediction of dimensionless jet machining parameters.

The data of graph 300 can be considered optimization correlation data used to correlate known mold Reynolds numbers with jet Reynolds numbers that can be used to determine optimal casting parameters, as disclosed in further detail herein . The data for graph 300 may be determined experimentally, by modeling, or by application of existing data.

By manipulating the casting parameters (e.g., the diameter of the nozzle opening and the flow rate of the molten metal exiting the nozzle) such that the resulting dimensionless jet processing parameters (e.g., the jet Reynolds number and the mold Reynolds number) fall on the appropriate predicted line of the graph 300 , the optimal liquid metal jet can be obtained. For example, for the aluminum alloy Al4.5Cu, an optimal set of casting parameters (e.g., nozzle size and metal flow rate) can be selected such that the resulting jet Reynolds number is about 88000 and the resulting mold Reynolds number is about 1600, which is at Line 308 is joined at point 318 . Other optimal casting parameters for the aluminum alloy Al4.5Cu or for other aluminum alloys can be obtained similarly.

Alloy composition can be an important parameter of the model because alloy composition affects the relative density of the solid phase and the steady state depth of the sump. Indeed, for DC casting where most of the heat is removed by a solid mass at the bottom, certain elements such as magnesium or zinc can significantly affect sump depth due to their low thermal conductivity relative to pure aluminium. This difference in sump depth affects the degree to which the jet expands. Since the centerline velocity of the jet will decrease with depth, different jet diameters may be expected for different alloy compositions. Experimental or modeling data can be used to generate boundary curves representing effective processing parameters typically used for minimum centerline segregation of a range of aluminum alloys in DC casting, as depicted in graph 300 . Graph 300 represents the range of predicted jet Reynolds number as a function of mold Reynolds number, where the jet and mold Reynolds numbers (i.e., Re _j and Re _m , respectively) are defined according to Equation 21 and Equation 22, respectively, where M ₁ and M _w represent the mold length and width, respectively.

Boundary lines 306 and 310 of shaded area 312 are created for two alloys identified as limiting cases (eg, aluminum alloys 5182 and 1050). Most aluminum alloys used in DC casting will fall between these boundaries.

In some cases, linear approximation may be used to estimate graph 300 in order to computationally quickly or computationally easily determine an optimal Reynolds number. For purposes of providing dimensionless numbers, the relationship to mold parameters is presented as a relationship to Reynolds number for use with various shapes of molds, however other relationships to mold parameters (eg, spatialized relationships) may be used.

Sample points 314, 316, 318, 320, 322 represent actual casting parameters used in the examples of Figures 5-9, as described below.

Figures 4 to 9 are contour diagrams plotted according to the intensity of macrosegregation at vertical and horizontal positions in various ingots of aluminum alloy Al4.5Cu cast using different techniques. The horizontal axis of each of these graphs represents the horizontal distance in mm from the center of the ingot, with the outside of the ingot at the left end of the graph and the center of the ingot at the right end of the graph. The vertical axis of each of these graphs represents the vertical distance in mm from the center of the ingot, with the outside of the ingot at the top of the graph and the center of the ingot at the bottom of the graph. The contour plot is based on a transverse section of the ingot taken along a plane perpendicular to the length of the ingot. The magnitude of the macrosegregation in these plots is given as the percent difference in solute concentration versus molten metal supply. For example, a macrosegregation intensity of -15 may indicate a solute concentration that is 15% lower than the expected solute concentration (e.g., the concentration of molten metal supplied by the furnace), while a macrosegregation intensity of 10 may indicate a higher than expected solute concentration 10% solute concentration. Thus, high positive and high negative numbers indicate strong and generally undesirable macrosegregation, while substantially low numbers (eg, near zero) indicate low and generally desirable macrosegregation.

4 is a contour plot 400 depicting macrosegregation intensity at vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast using prior art techniques without the liquid metal jet optimization techniques disclosed herein. As shown in graph 400, significant negative macrosegregation (e.g., at or around -10% or -15%). Additionally, a pronounced positive macroscopic pattern is seen in certain regions between the center of the ingot and the outside of the ingot (e.g., at or about 100 mm from the center along the vertical axis and between 200 and 500 mm from the center along the horizontal axis). Segregation. The areas of strong macrosegregation seen in ingots cast without the use of the liquid metal jet optimization techniques disclosed herein were relatively large and continuous.

5 to 9 are contour plots of aluminum alloy Al4.5Cu ingots cast using various degrees of the liquid metal jet optimization technique disclosed herein across different jet Reynolds numbers but maintaining a constant mold Reynolds number of approximately 1600. The jet Reynolds number was varied for the ingot cast by changing the nozzle opening used during casting, while all other casting parameters were kept constant. The jet Reynolds numbers depicted in FIGS. 5 to 9 correspond to points 314 , 316 , 318 , 320 , 322 of FIG. 3 .

5 is a diagram depicting vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast according to parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 64000 Contour plot 500 of macrosegregation intensity. As seen in graph 500, there is little or no negative segregation near the center of the ingot, however, there is some positive segregation near the center of the ingot and the short edges of the ingot.

6 is a graph depicting vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast according to parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 69000 Contour plot 600 of macrosegregation intensity. As seen in graph 600, there is little or no negative segregation near the center of the ingot, however, there is some positive segregation near the center of the ingot and near the edges of the ingot.

7 is a diagram depicting vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast according to parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 81000 Contour plot 700 of macrosegregation intensity. As seen in graph 700, there is little or no negative segregation near the center of the ingot, however, there is some positive segregation near the center of the ingot and the long sides of the ingot. Overall, however, the macrosegregation intensity across the cross-section depicted in graph 700 is mostly close to zero (eg, within ±5% or ±10% variation in solute concentration from the molten metal supply).

8 is a graph depicting vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast according to parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 97000 Contour map 800 of macrosegregation intensity. As seen in graph 800, there is very little segregation over most of the cross-section, except for some positive segregation along the edges of the ingot.

9 is a graph depicting vertical and horizontal positions in an aluminum alloy Al4.5Cu ingot cast according to parameters set to achieve a mold Reynolds number of about 1600 and a nozzle opening selected to achieve a jet Reynolds number of about 121000 Contour map 900 of macrosegregation intensity. As seen in graph 900, there is very little segregation over most of the cross-section, except for some positive segregation along the edges of the ingot.

As shown in Figures 5-9, ingots cast using jet Reynolds numbers below about 97,000 exhibit positive (eg, enriched) centerline segregation (eg, as opposed to the negative segregation observed in Figure 4). In addition, ingots cast using a jet Reynolds number of 97,000 or above exhibit very low centerline segregation, and, if present, negative (eg, depletion) segregation. In addition, as opposed to the absence of such jets (as seen, for example, in FIG. 4 ), when a certain degree of optimized liquid metal jets are used (as seen, for example, in FIGS. 5 to 9 ), the extent of the centerline region is relatively short. The axis is significantly narrower.

Figures 4 to 9 illustrate the possibility of optimized liquid metal jets to alter the centerline segregation of DC cast products such as rolled plate ingots. The fact that the centerline segregation zone itself is reduced may be desirable since thermomechanical working of the ingot reduces residual segregation. A more quantitative process performance analysis can be performed using a macroscopic segregation index (MI) metric that quantifies the degree of centerline segregation. Equation 23 is a modified second zone moment equation that assigns a quantitative value to the concentration measured at each location based on its deviation from the target alloy composition and its distance from the center , where Y is the half-thickness of the ingot, A _dom is the area of the plate cross-section being measured, y is the distance from the mid-thickness of the measuring point, A is a delimiter indicating the boundary of the integration above the ingot cross-section, C ₀ is the solute concentration of the target alloy composition, and C is the solute concentration at the location measured (eg, the distance through the thickness of the ingot).

Blank (along radius or diameter). Ingot (through thickness)

Incorporating distance in the metric may be important because enriched chill regions, which may be addressed by post-cast physical means, may distort the analysis of entire sections of the ingot. Since the index contains squared terms, it treats positive or negative segregation as equally unfavorable. MI is smallest for cross-sections with less macrosegregation (eg, where the change in solute concentration from the molten metal supply is closest to zero).

10 is a graph 1000 depicting macrosegregation index (MI) as a function of jet Reynolds number for each of the ingots of FIGS. 5-9. Dashed line 1002 represents the MI of the standard ingot of Figure 4, which depicts a MI of approximately 0.104. In some cases, a suitable metal jet in accordance with certain aspects of the present disclosure may produce a metal jet having an , 0.055, 0.050, 0.045 or 0.040 MI ingots or billets.

Point 1022 depicts an MI of approximately 0.06 for the ingot of FIG. 5 having a jet Reynolds number of 64000, which point is associated with point 322 of FIG. 3 . Point 1020 depicts an MI of approximately 0.07 for the ingot of FIG. 6 having a jet Reynolds number of 69000, which point is associated with point 320 of FIG. 3 . Point 1018 depicts an MI of approximately 0.06 for the ingot of FIG. 7 having a jet Reynolds number of 81000, which point is associated with point 318 of FIG. 3 . Point 1016 depicts an MI of about 0.04 for the ingot of FIG. 8 having a jet Reynolds number of 97000, which point is associated with point 316 of FIG. 3 . Point 1014 depicts an MI of about 0.07 for the ingot of FIG. 9 having a jet Reynolds number of 121000, which point is associated with point 314 of FIG. 3 .

For the range of jet Reynolds numbers depicted in Figures 5 to 9, the macrosegregation index shows a reduction of at least about 30% compared to the standard casting method. A best performing jet with a jet Reynolds number of 97,000 showed approximately a 60% reduction in centerline segregation. In some cases, a suitable metal jet according to certain aspects of the present disclosure can reduce centerline segregation by more than about 5%, 10%, 15%, 20%, 25%, 30% compared to standard casting methods , 35%, 40%, 45%, 50%, 55%, 60%, or 65%.

As described herein, a dimensionless model can be used to determine casting parameters for various aluminum alloys and various mold sizes.

11 is a flowchart depicting a process 1100 for determining optimal casting parameters based on known molds, according to certain aspects of the present disclosure. At block 1102, mold dimensions may be determined. Die dimensions may comprise any suitable dimensions for determining Reynolds number, as described herein. For example, the length and width dimensions can be determined for a rectangular mold, however, other dimensions can be determined for different shaped molds. Mold dimensions may be predetermined based on other criteria, such as the desired ingot size or the pre-existence of suitable molds. An example of a method of dimensioning a mold may be to measure an existing mold, thereby determining measurements from a graph or plan (eg, by computer-aided design), or to preset measurements for a mold to be produced. At block 1104, a casting speed may be determined. The casting speed may be predetermined based on other casting considerations. In some cases, determining the casting speed at block 1104 may include determining a number of potential desired casting speeds, which may further be used to determine a number of potential mold Reynolds numbers at block 1106, which may be used to calculate A plurality of optimized casting parameters which in turn can be used to select one of the plurality of casting speeds to be used.

At block 1106, the mold Reynolds number is determined. The mold Reynolds number may be determined using Equation 22 and the mold size determined at block 1102 and the casting speed determined at block 1104 . As an example, a mold with dimensions of 1.5m x 0.7m can provide The Reynolds number of the mold, the casting speed and the sinking rate of the dimple are kept equal at the mold size, about 0.001 m/s.

At optional block 1110, metal composition may be determined. For example, the desired metal composition (eg, type of aluminum alloy) can be determined by testing samples, checking a database, or manual entry. In some cases, a generic metal composition may be assumed when the actual metal composition is uncertain.

At block 1108, the jet Reynolds number is determined. The jet Reynolds number may be determined by matching the mold Reynolds number determined at block 1106 with optimization-related data defining an optimal relationship between the mold Reynolds number and the jet Reynolds number. Optimization-related data may be in the form of a graph (e.g., graph 300 of FIG. 3 ) or in an equation (e.g., an equation defining a line or estimate from graph 300 of FIG. 3 (e.g., following the linear approximation of [1]) ) or as a single data point. Optimization-related data may also take other forms. In some cases, the metallic composition determined at block 1110 may be used with optimization correlation data to determine the jet Reynolds number. In the above example of a mold with a mold Reynolds number of about 1735, the corresponding jet Reynolds number of the aluminum alloy Al4.5Cu may be about 78000, as depicted in FIG. 3 .

In some cases, optimization-related data may be obtained experimentally. In some cases, optimization-related data may be obtained as described above with reference to FIG. 3 .

At block 1112 , desired casting parameters may be determined based on the determined jet Reynolds number from block 1108 and the determined mold Reynolds number from block 1106 . In some cases, determining desired casting parameters may include determining a desired metal flow rate at block 1114 . In some cases, determining desired casting parameters may include determining a nozzle opening size at block 1116 . In some cases, the radius of the nozzle opening (b ₀ ) can be determined by applying the mold Reynolds number from block 1106 and the jet Reynolds number from block 1108 to Equations 21 and 22 such that In the above example where the jet Reynolds number was determined to be approximately 78000, the radius of the nozzle opening can be calculated as

At optional block 1118 , the casting environment may be prepared using the optimized casting parameters determined at block 1112 . The casting environment may be prepared by fabricating or selecting nozzles with appropriate nozzle opening sizes as determined at block 1116 . In the above example where the Reynolds number was determined to be about 78000, a suitable nozzle may be selected, such as a nozzle with an opening of about 15.6 radii or 31.2 mm diameter. In some cases, preparing the casting environment may include attaching suitable nozzles to casting equipment associated with the particular mold used to determine the mold Reynolds number at block 1106 . In some cases, the casting environment may be prepared by controlling the molten metal flow control device based on the metal flow rate determined at block 1114 .

The foregoing descriptions of the embodiments, including the illustrated embodiments, have been presented for purposes of illustration and description only, and are not intended to be exhaustive or to be limited to the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be readily apparent to those skilled in the art.

As used hereinafter, any reference to a series of examples should be read as a separate reference to each of those examples (eg, "Examples 1 to 4" should be read as "Examples 1, 2, 3, or 4").

Example 1 is a direct chill casting system comprising: a mold cavity; a supply of molten metal for providing molten metal to the mold cavity; and a nozzle coupled to the supply of molten metal and having a size sized to produce An opening for a flow rate that causes the liquid metal jet to have sufficient force to cause resuspension of grains in the slurry zone of the melt sump without changing the shape of the slurry zone during steady state operation.

Example 2 is the system of Example 1, wherein the opening of the nozzle is sized such that the jet of liquid metal has sufficient force to cause a depression in the melt sump casting the metal product at the casting speed, wherein the opening of the nozzle is sized Set such that the resulting jet of liquid metal causes the dimple descent speed of the dimples to have a variation of 10% or less from the casting speed during steady state operation.

Example 3 is the system of Example 1 or 2, further comprising a bottom block extending distally from the nozzle at a casting speed during steady state operation.

Example 4 is the system of Examples 1-3, further comprising a flow control device coupled between the supply of molten metal and the nozzle for controlling a flow rate of the molten metal into the mold cavity.

Example 5 is the system of Example 4, further comprising a controller coupled to the sensor to estimate the depth of the smelt sump and coupled to the flow control device to adjust the flow rate of the molten metal based on the estimated depth of the smelt sump.

Example 6 is a method of optimizing metal casting during a casting operation comprising: determining a mold size for a mold cavity suitable for receiving liquid metal from a nozzle coupled to a source of liquid metal; determining a casting speed; and using the mold size and casting speed to determine optimized casting parameters, wherein determining the optimized casting parameters includes determining at least one of the metal flow rate and the opening size of the nozzle so that the liquid metal jet produced by the liquid metal leaving the nozzle opening at the metal flow rate is suitable for use in molten metal Resuspension of the grains is induced in the slurry zone of the tank without changing the shape of the slurry zone during steady state operation.

Example 7 is the method of Example 6, wherein determining optimized casting parameters includes ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet has sufficient force to cause a crater in the melt sump, wherein for The opening of the nozzle is sized such that the resulting jet of liquid metal causes the dimple drop rate of the dimple to have a variation of 10% or less from the casting speed during steady state operation.

Example 8 is the method of example 6 or 7, wherein determining optimized casting parameters comprises: using mold size and casting speed to determine mold Reynolds number; using mold Reynolds number to determine jet Reynolds number; and using mold Reynolds number and jet Reynolds number to determine Calculation of optimized casting parameters.

Example 9 is the method of example 8, wherein determining the jet Reynolds number comprises determining a metallic composition of the cast product and using the metallic composition and the mold Reynolds number to determine the jet Reynolds number.

Example 10 is the method of Examples 6 to 9, wherein the optimized casting parameter is the opening size of the nozzle.

Example 11 is the method of Examples 6 to 10, further comprising selecting or fabricating the nozzle based on the size of the opening of the nozzle.

Example 12 is the method of Examples 6 to 11, further comprising controlling the flow control device using a metal flow rate.

Example 13 is a method of casting a metal product comprising: providing molten metal from a supply of molten metal at a flow rate through an opening of a nozzle to a mold cavity during steady state operation, wherein the molten metal provided at a flow rate through the opening of the nozzle is contained in generating a jet of liquid metal in the smelt tank; and using the jet of liquid metal to resuspend the grains in the slurry zone of the smelt tank without changing the shape of the slurry zone during steady state operation.

Example 14 is the method of Example 13, wherein the opening is sized such that the liquid metal jet has sufficient force to induce dimples in the slurry zone and maintain the dimple drop rate at a difference from the casting speed during steady state operation Within 10% variation.

Example 15 is the method of Example 14, further comprising: fabricating or selecting the nozzle to have an opening size suitable for producing a liquid metal jet having sufficient force to maintain a dimple descent velocity at within 10% of the casting speed; and coupling the nozzle to a molten metal supply.

Example 16 is the method of examples 13 to 15, further comprising retracting the bottom block away from the nozzle during steady state operation.

Example 17 is the method of examples 13 to 16, wherein providing the molten metal at a flow rate through the nozzle further comprises controlling the flow rate using a flow control device coupled between the molten metal supply and the nozzle.

Example 18 is the method of Example 17, wherein using the liquid metal jet to resuspend the grains includes controlling the flow rate through the opening to ensure that the liquid metal jet has sufficient force to maintain the dimple drop rate within 5% of the casting speed during steady state operation within the changes.

Example 19 is the method of examples 13 to 18, wherein resuspending the grains using the liquid metal jet comprises orienting the liquid metal jet in a direction at or within 30° from vertical.

Example 20 is a cast metal product produced using the method of Examples 13 to 19, wherein the cast metal product has a macrosegregation index of less than 0.104.

Example 21 is a metal product having a macrosegregation index at or below 0.10, wherein the metal product is cast in a mold cavity using a nozzle coupled to a supply of molten metal to be sized to produce a flow rate such that the liquid metal The jet enters an opening in the melt sump to introduce molten metal into the mold cavity.

Example 22 is the metal product of Example 21, wherein the macrosegregation index is calculated according to:

where Y is the half-thickness or half-diameter of the metal product, A _dom is the area of the measured cross-section of the measuring point, y is the distance from the mid-thickness of the measuring point, and A is the delimitation of the integral boundary above the cross-section indicating the metal product , C ₀ is the solute concentration of the target alloy composition, and C is the solute concentration at the measurement point.

Example 23 is the metal product of Example 21 or 22, wherein the liquid metal jet has sufficient force to cause resuspension of grains in the slurry zone of the melt storage tank without altering the slurry zone during steady state operation. shape.

Example 24 is the metal product of Examples 21 to 23, wherein the opening of the nozzle is sized such that the jet of liquid metal has sufficient force to cause a depression in the melt sump, wherein the opening of the nozzle is sized such that The jet of liquid metal produced during steady state operation causes the dimple descent speed of the dimples to have a variation of 10% or less from the casting speed.

Example 25 is the metal product of Examples 21 to 24, wherein the liquid metal jet has sufficient force to induce fluid flow within the smelt sump sufficient to homogenize the solute concentration throughout the smelt sump.

Example 26 is the metal product of Examples 21 to 25, wherein the Macrosegregation Index is at or below 0.090.

Example 27 is the metal product of Examples 21 to 26, wherein the Macrosegregation Index is at or below 0.070.

Example 28 is the metal product of Examples 21 to 27, wherein the flow control device is coupled between the supply of molten metal and the nozzle for controlling the flow rate of molten metal into the mold cavity.

Example 29 is the metal product of example 28, wherein the controller is coupled to the sensor to estimate the depth of the smelt sump and to the flow control device to adjust the flow rate of the molten metal based on the estimated depth of the smelt sump.

Example 30 is a method of optimizing metal casting during a casting operation comprising: determining a mold size for a mold cavity suitable for receiving liquid metal from a nozzle coupled to a source of liquid metal; determining a casting speed; and using the mold size and casting speed to determine optimized casting parameters, wherein determining the optimized casting parameters includes determining at least one of the metal flow rate and the opening size of the nozzle so that the liquid metal jet produced by the liquid metal leaving the nozzle opening at the metal flow rate is suitable for reducing the cast metal Macrosegregation of the product such that the metal product cast using optimized casting parameters has a macrosegregation index at or below 0.100.

Example 31 is the method of example 30, wherein the macrosegregation index is calculated according to:

where Y is the half-thickness or half-diameter of the metal product, A _dom is the area of the measured cross-section of the measuring point, y is the distance from the mid-thickness of the measuring point, and A is the delimitation of the integral boundary above the cross-section indicating the metal product , C ₀ is the solute concentration of the target alloy composition, and C is the solute concentration at the measurement point.

Example 32 is the method of example 30 or 31, wherein determining the optimized casting parameters comprises ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet is suitable for inducing grains in the slurry region of the melt sump resuspension without changing the shape of the slurry zone during steady state operation.

Example 33 is the method of Examples 30 to 32, wherein determining the optimized casting parameters comprises ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet has sufficient force to cause a crater in the melt sump, Wherein the opening of the nozzle is sized such that the resulting jet of liquid metal causes the dimple drop rate of the dimple to have a variation of 10% or less from the casting speed during steady state operation.

Example 34 is the method of examples 30 to 33, wherein determining optimized casting parameters comprises: using the mold size and casting speed to determine the mold Reynolds number; using the mold Reynolds number to determine the jet Reynolds number; and using the mold Reynolds number and the jet Reynolds number to determine Calculation of optimized casting parameters.

Example 35 is the method of example 34, wherein determining the jet Reynolds number comprises determining a metallic composition of the cast product and using the metallic composition and the mold Reynolds number to determine the jet Reynolds number.

Example 36 is the method of examples 30 to 35, wherein the optimized casting parameter is the opening size of the nozzle.

Example 37 is the method of examples 30 to 36, further comprising selecting or fabricating the nozzle based on an opening size of the nozzle.

Example 38 is the method of examples 30-37, further comprising using the metal flow rate to control the flow control device.

Example 39 is the method of Examples 30 to 38, wherein determining optimized casting parameters includes ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet has sufficient force to cause sufficient Fluid flow that homogenizes solute concentration throughout the melt sump.

Example 40 is the method of Examples 30 to 39, wherein the Macrosegregation Index is at or below 0.090.

Example 41 is the method of Examples 30 to 40, wherein the Macrosegregation Index is at or below 0.070.

Example 42 is a method of casting a metal product comprising: providing molten metal from a supply of molten metal at a flow rate through an opening of a nozzle to a mold cavity during steady state operation, wherein the molten metal provided at a flow rate through the opening of the nozzle is contained in A jet of liquid metal is generated in the melt tank sufficient to reduce macrosegregation in the metal product such that the metal product has a macrosegregation index at or below 0.100.

Example 43 is the method of example 42, wherein the macrosegregation index is calculated according to:

where Y is the half-thickness or half-diameter of the metal product, A _dom is the area of the measured cross-section of the measuring point, y is the distance from the mid-thickness of the measuring point, and A is the delimitation of the integral boundary above the cross-section indicating the metal product , C ₀ is the solute concentration of the target alloy composition, and C is the solute concentration at the measurement point.

Example 44 is the method of example 42 or 43, further comprising using the liquid metal jet to resuspend the grains in the slurry zone of the melt tank without changing the shape of the slurry zone during steady state operation.

Example 45 is the method of Example 44, wherein the opening is sized such that the liquid metal jet has sufficient force to create a dimple in the slurry zone and maintain the dimple drop rate at a difference from the casting speed during steady state operation Within 10% variation.

Example 46 is the method of Examples 42 to 45, further comprising causing a fluid flow within the smelt sump sufficient to homogenize the solute concentration throughout the smelt sump.

Example 47 is the method of examples 42 to 46, wherein providing the molten metal at a flow rate through the nozzle further comprises controlling the flow rate using a flow control device coupled between the molten metal supply and the nozzle.

Example 48 is the method of Examples 42 to 47, wherein the Macrosegregation Index is at or below 0.090.

Example 49 is the method of Examples 42 to 48, wherein the Macrosegregation Index is at or below 0.070.

Claims (49)

1. A direct chilled casting system comprising: cavity; a supply of molten metal for supplying the molten metal to the mold cavity; and a nozzle coupled to said supply of molten metal and having an opening sized to produce a flow velocity causing a jet of liquid metal to have sufficient force to cause re-graining in the slurry region of the melt sump suspension without changing the shape of the slurry zone during steady state operation. 2. The system of claim 1, wherein the opening of the nozzle is sized such that the jet of liquid metal has sufficient force to cast a metal product in the melt sump at a casting speed causing dimples, wherein the opening of the nozzle is sized such that the jet of liquid metal produced causes the dimples to have a dimple drop rate that differs by 10% from the casting speed during steady state operation or smaller changes. 3. The system of claim 1, further comprising a bottom block extending distally from the nozzle at a casting speed during steady state operation. 4. The system of claim 1, further comprising a flow control device coupled between the supply of molten metal and the nozzle for controlling the flow rate of the molten metal into the mold cavity . 5. The system of claim 4, further comprising a controller coupled to a sensor to estimate the depth of the smelt sump and to the flow control device to estimate the depth of the smelt sump based on the estimated depth of the smelt sump. to adjust the flow rate of the molten metal. 6. A method for optimizing metal casting during a casting operation comprising: determining mold dimensions for a mold cavity adapted to receive liquid metal from a nozzle coupled to a source of liquid metal; determine casting speed; and The mold size and the casting speed are used to determine optimized casting parameters, wherein determining the optimized casting parameters includes determining at least one of a metal flow rate and an opening size of the nozzle such that liquid metal is passed through at the metal flow rate The jet of liquid metal produced from the opening of the nozzle is adapted to cause resuspension of grains in the slurry zone of the melt sump without changing the shape of the slurry zone during steady state operation. 7. The method of claim 6, wherein determining the optimized casting parameters includes ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet has sufficient force to induce a dimple in the melt sump, wherein the opening of the nozzle is sized such that the jet of liquid metal produced causes a dimple descent rate of the dimple to operate in a steady state period with a variation of 10% or less from the casting speed. 8. The method of claim 6, wherein determining optimized casting parameters comprises: using said mold dimensions and said casting speed to determine a mold Reynolds number; using the mold Reynolds number to determine a jet Reynolds number; and The optimized casting parameters are calculated using the mold Reynolds number and the jet Reynolds number. 9. The method of claim 8, wherein determining the jet Reynolds number comprises determining a metallic composition of a cast product and using the metallic composition and the mold Reynolds number to determine the jet Reynolds number. 10. The method of claim 6, wherein the optimized casting parameter is the opening size of the nozzle. 11. The method of claim 6, further comprising selecting or manufacturing the nozzle based on the opening size of the nozzle. 12. The method of claim 6, further comprising using the metal flow rate to control a flow control device. 13. A method of casting a metal product comprising: Providing molten metal from a molten metal supply to the mold cavity at a flow rate through an opening of a nozzle during steady state operation wherein providing molten metal at the flow rate through the opening of the nozzle comprises producing liquid metal in a melt sump jet; and The liquid metal jet is used to resuspend the grains in the slurry zone of the melt tank without changing the shape of the slurry zone during steady state operation. 14. The method of claim 13, wherein the opening is sized such that the liquid metal jet has sufficient force to create a dimple in the slurry zone and to displace the dimple during steady state operation. The pit descent speed was maintained within a 10% variation from the casting speed. 15. The method of claim 14, further comprising: fabricating or selecting the nozzle to have an opening size suitable for producing the liquid metal jet having sufficient force to maintain the dimple descent rate at the same rate as the casting during the steady state operation within 10% of the speed difference; and The nozzle is coupled to the molten metal supply. 16. The method of claim 13, further comprising retracting a bottom block away from the nozzle during steady state operation. 17. The method of claim 13, wherein providing the molten metal at the flow rate through the nozzle further comprises controlling the flow rate using a flow control device coupled between the molten metal supply and the nozzle. flow rate. 18. The method of claim 17, wherein using the liquid metal jet to resuspend the grains comprises controlling the flow rate through the opening to ensure that the liquid metal jet has sufficient force to The dimple drop rate was maintained within a 5% variation from the casting rate. 19. The method of claim 13, wherein using the liquid metal jet to resuspend the grains comprises orienting the liquid metal jet in a direction at or within 30° from vertical. 20. A cast metal product produced using the method of claim 13, wherein the cast metal product has a macrosegregation index of less than 0.104. 21. A metal product having a macrosegregation index at or below 0.10, wherein said metal product is cast in a mold cavity using a nozzle coupled to a supply of molten metal to be sized to produce a flow rate such that The molten metal is introduced into the mold cavity by passing a jet of liquid metal into an opening in a melt sump. 22. The metal product of claim 21, wherein the macrosegregation index is calculated according to: where Y is the half-thickness or half-diameter of the metal product, A _dom is the area of the measured cross-section of the measuring point, y is the distance from the middle thickness of the measuring point, and A is the area above the cross-section indicating the metal product. The delimiter of the integration boundary, _C0 is the solute concentration of the target alloy composition, and C is the solute concentration at the measurement point. 23. The metal product of claim 21 , wherein the liquid metal jet has sufficient force to cause resuspension of grains in the slurry region of the melt storage tank without during steady state operation The shape of the slurry zone is changed. 24. The metal product of claim 21 , wherein the opening of the nozzle is sized such that the jet of liquid metal has sufficient force to cause a depression in the melt sump, wherein The opening of the nozzle is sized such that the jet of liquid metal produced during steady state operation causes the dimple drop rate of the dimple to have a variation of 10% or less from the casting speed. 25. The metal product of claim 21 , wherein the liquid metal jet has sufficient force to induce a fluid flow within the smelt sump sufficient to homogenize the solute concentration throughout the smelt sump . 26. The metal product of claim 21, wherein the macrosegregation index is at or below 0.090. 27. The metal product of claim 21, wherein the macrosegregation index is at or below 0.070. 28. The metal product of claim 21, wherein a flow control device is coupled between the supply of molten metal and the nozzle for controlling the flow rate of the molten metal into the mold cavity. 29. The metal product of claim 28, wherein a controller is coupled to a sensor to estimate the depth of the smelt sump and to the flow control device to determine based on the estimated depth of the smelt sump. The flow rate of the molten metal is adjusted. 30. A method for optimizing metal casting during a casting operation comprising: determining mold dimensions for a mold cavity adapted to receive liquid metal from a nozzle coupled to a source of liquid metal; determine casting speed; and The mold size and the casting speed are used to determine optimized casting parameters, wherein determining the optimized casting parameters includes determining at least one of a metal flow rate and an opening size of the nozzle such that liquid metal is passed through at the metal flow rate The jet of liquid metal exiting said opening of said nozzle is adapted to reduce macrosegregation of the cast metal product such that the metal product cast using said optimized casting parameters has a macrosegregation index at or below 0.100. 31. The method of claim 30, wherein the macrosegregation index is calculated according to: where Y is the half-thickness or half-diameter of the metal product, A _dom is the area of the measured cross-section of the measuring point, y is the distance from the middle thickness of the measuring point, and A is the area above the cross-section indicating the metal product. The delimiter of the integration boundary, _C0 is the solute concentration of the target alloy composition, and C is the solute concentration at the measurement point. 32. The method of claim 30, wherein determining the optimized casting parameters includes ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet is suitable for melting resuspension of the grains in the slurry zone of the material storage tank without changing the shape of the slurry zone during steady state operation. 33. The method of claim 30, wherein determining the optimized casting parameters includes ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet has sufficient force to induce a dimple in the melt sump, wherein the opening of the nozzle is sized such that the jet of liquid metal produced causes a dimple descent rate of the dimple to operate in a steady state period with a variation of 10% or less from the casting speed. 34. The method of claim 30, wherein determining optimized casting parameters comprises: using said mold dimensions and said casting speed to determine a mold Reynolds number; using the mold Reynolds number to determine a jet Reynolds number; and The optimized casting parameters are calculated using the mold Reynolds number and the jet Reynolds number. 35. The method of claim 34, wherein determining the jet Reynolds number comprises determining a metallic composition of a cast product and using the metallic composition and the mold Reynolds number to determine the jet Reynolds number. 36. The method of claim 30, wherein the optimized casting parameter is the opening size of the nozzle. 37. The method of claim 30, further comprising selecting or manufacturing the nozzle based on the opening size of the nozzle. 38. The method of claim 30, further comprising using the metal flow rate to control a flow control device. 39. The method of claim 30, wherein determining the optimized casting parameters comprises ensuring that at least one of the metal flow rate and the opening size of the nozzle is calculated such that the liquid metal jet has sufficient force to induce fluid flow within the smelt sump sufficient to homogenize the solute concentration throughout the smelt sump. 40. The method of claim 30, wherein the macrosegregation index is at or below 0.090. 41. The method of claim 30, wherein the macrosegregation index is at or below 0.070. 42. A method of casting a metal product comprising: During steady state operation molten metal is supplied to the mold cavity from a molten metal supply at a flow rate through the opening of the nozzle at which the molten metal contained in the melt sump produces sufficient A liquid metal jet that reduces macrosegregation in said metal product such that said metal product has a macrosegregation index at or below 0.100. 43. The method of claim 42, wherein the macrosegregation index is calculated according to: where Y is the half-thickness or half-diameter of the metal product, A _dom is the area of the measured cross-section of the measuring point, y is the distance from the middle thickness of the measuring point, and A is the area above the cross-section indicating the metal product. The delimiter of the integration boundary, _C0 is the solute concentration of the target alloy composition, and C is the solute concentration at the measurement point. 44. The method of claim 42, further comprising using the liquid metal jet to resuspend grains in a slurry zone of a melt storage tank without altering the slurry zone during steady state operation shape. 45. The method of claim 44, wherein the opening is sized such that the liquid metal jet has sufficient force to create a dimple in the slurry zone and to displace the dimple during steady state operation. The pit descent speed was maintained within a 10% variation from the casting speed. 46. The method of claim 42, further comprising inducing fluid flow within the smelt sump sufficient to homogenize the solute concentration throughout the smelt sump. 47. The method of claim 42, wherein providing the molten metal at the flow rate through the nozzle further comprises controlling the flow rate using a flow control device coupled between the molten metal supply and the nozzle. flow rate. 48. The method of claim 42, wherein the macrosegregation index is at or below 0.090. 49. The method of claim 42, wherein the macrosegregation index is at or below 0.070.