US2017274446A1PendingUtilityA1
Liquid metal jet optimization in direct chill casting
Est. expiryMar 25, 2036(~9.6 yrs left)· nominal 20-yr term from priority
Inventors:Samuel R. Wagstaff
C22C 21/12B22D 11/003B22D 11/049B22D 37/00B22D 21/007B22D 15/04B22D 11/10B22D 11/103B22D 7/00
46
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Claims
Abstract
A liquid metal jet supplying molten metal during a direct chill casting operation can be optimized to erode the slurry region of the molten sump, but not the solidified metal, at a rate equal to the casting speed. A model of the erosion of solidifying grains in the slurry region of the molten sump can be non-dimensionalized to be used to generate casting parameters (e.g., optimally sized nozzle openings and optimal molten metal flow rates) that would provide the optimized liquid metal jet during the casting process. An ingot cast using such an optimized liquid metal jet would have improved macrosegregation properties (e.g., reduced macrosegregation or more evenly distributed macrosegregation), such as having ingot solute concentrations varying from the molten metal supply concentration approximately 10% or less or 5% or less across the width or height of the ingot.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A direct chill casting system, comprising:
a mold cavity; a supply of molten metal for providing the molten metal to the mold cavity; and a nozzle coupled to the supply of molten metal and having an opening sized to produce a flow rate inducing a liquid metal jet having sufficient force to induce re-suspension of grains in a slurry region of a molten sump without altering a shape of the slurry region during steady state operation.
2 . The system of claim 1 , wherein the opening of the nozzle is sized such that the liquid metal jet has sufficient force to induce a crater in the molten sump of a metal product being cast at a casting speed, wherein the opening of the nozzle is sized such that the liquid metal jet produced induces a crater descent velocity of the crater having a variation of 10% or less from the casting speed during steady state operation.
3 . The system of claim 1 , further comprising a bottom block for extending away 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 a 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 a depth of the molten sump and coupled to the flow control device to adjust the flow rate of the molten metal based on the estimated depth of the molten sump.
6 . A method for optimizing metal casting during a casting operation, comprising:
determining mold dimensions for a mold cavity suitable for receiving liquid metal from a nozzle coupled to a liquid metal source; determining a casting speed; and determining an optimized casting parameter using the mold dimensions and the casting speed, wherein determining the optimized casting parameter includes determining at least one of a metal flow rate and an opening size of the nozzle such that a liquid metal jet produced by liquid metal exiting the opening of the nozzle at the metal flow rate is suitable for inducing re-suspension of grains in a slurry region of a molten sump without altering a shape of the slurry region during steady state operation.
7 . The method of claim 6 , wherein determining the optimized casting parameter comprises ensuring at least one of the metal flow rate and the opening size of the nozzle is calculated so that the liquid metal jet has sufficient force to induce a crater in the molten sump, wherein the opening of the nozzle is sized such that the liquid metal jet produced induces a crater descent velocity of the crater having a variation of 10% or less from the casting speed during steady state operation.
8 . The method of claim 6 , wherein determining an optimized casting parameter comprises:
determining a mold Reynolds number using the mold dimensions and the casting speed; determining a jet Reynolds number using the mold Reynolds number; and calculating the optimized casting parameter 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 metal composition of the product being cast and determining the jet Reynolds number using the metal composition and the mold 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 fabricating the nozzle based on the opening size of the nozzle.
12 . The method of claim 6 , further comprising controlling a flow control device using the metal flow rate.
13 . A process of casting a metal product comprising:
providing molten metal from a molten metal supply to a mold cavity through an opening of a nozzle at a flow rate during steady state operation, wherein providing molten metal through the opening of the nozzle at the flow rate includes producing a liquid metal jet in a molten sump; and re-suspending grains in a slurry region of a molten sump, using the liquid metal jet, without altering a shape of the slurry region during steady state operation.
14 . The process of claim 13 , wherein the opening is sized such that the liquid metal jet has sufficient force to produce a crater in the slurry region and maintain a crater descent velocity within a 10% variation from a casting speed during steady state operation.
15 . The process 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 crater descent velocity within the 10% variation from the casting speed during the steady state operation; and coupling the nozzle to the molten metal supply.
16 . The process of claim 13 , further comprising retracting a bottom block away from the nozzle during steady state operation.
17 . The process of claim 13 , wherein providing the molten metal through the nozzle at the flow rate further comprises controlling the flow rate using a flow control device coupled between the molten metal supply and the nozzle.
18 . The process of claim 17 , wherein re-suspending the grains using the liquid metal jet comprises controlling the flow rate through the opening to ensure the liquid metal jet has sufficient force to maintain the crater descent velocity within a 5% variation from a casting speed during steady state operation.
19 . The process of claim 13 , wherein re-suspending the grains using the liquid metal jet comprises orienting the liquid metal jet in a direction at or within 30° from vertical.
20 . A cast metal product producing using the process of claim 13 , wherein the cast metal product has a macrosegregation index below 0.104.
21 . 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 direct the molten metal into the mold cavity through an opening sized to produce a flow rate inducing a liquid metal jet into a molten sump.
22 . The metal product of claim 21 , wherein the macrosegregation index is calculated according to:
Macrosegregation
Index
=
1
C
0
[
Y
A
dom
∫
∫
A
(
C
-
C
0
)
2
1
y
dA
]
1
/
2
wherein Y is a half thickness or a half diameter of the metal product, A dom is an area of a measured cross section of a measured point, y is a distance from a mid-thickness of the measured point, A is a delimiter indicating boundaries of integration over a cross section of the metal product, C 0 is a solute concentration of a target alloy composition, and C is a solute concentration at the measured point.
23 . The metal product of claim 21 , wherein the liquid metal jet has sufficient force to induce re-suspension of grains in a slurry region of the molten sump without altering a shape of the slurry region during steady state operation.
24 . The metal product of claim 21 , wherein the opening of the nozzle is sized such that the liquid metal jet has sufficient force to induce a crater in the molten sump, wherein the opening of the nozzle is sized such that the liquid metal jet produced induces a crater descent velocity of the crater having a variation of 10% or less from a casting speed during steady state operation.
25 . The metal product of claim 21 , wherein the liquid metal jet has sufficient force to induce fluid flow within the molten sump sufficient to homogenize solute concentrations throughout the molten 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 a 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 a depth of the molten sump and coupled to the flow control device to adjust the flow rate of the molten metal based on the estimated depth of the molten sump.
30 . A method for optimizing metal casting during a casting operation, comprising:
determining mold dimensions for a mold cavity suitable for receiving liquid metal from a nozzle coupled to a liquid metal source; determining a casting speed; and determining an optimized casting parameter using the mold dimensions and the casting speed, wherein determining the optimized casting parameter includes determining at least one of a metal flow rate and an opening size of the nozzle such that a liquid metal jet produced by liquid metal exiting the opening of the nozzle at the metal flow rate is suitable for reducing macrosegregation in a cast metal product such that a metal product cast using the optimized casting parameter has a macrosegregation index at or below 0.100.
31 . The method of claim 30 , wherein the macrosegregation index is calculated according to:
Macrosegregation
Index
=
1
C
0
[
Y
A
dom
∫
∫
A
(
C
-
C
0
)
2
1
y
dA
]
1
/
2
wherein Y is a half thickness or a half diameter of the metal product, A dom is an area of a measured cross section of a measured point, y is a distance from a mid-thickness of the measured point, A is a delimiter indicating boundaries of integration over a cross section of the metal product, C 0 is a solute concentration of a target alloy composition, and C is a solute concentration at the measured point.
32 . The method of claim 30 , wherein determining the optimized casting parameter comprises ensuring at least one of the metal flow rate and the opening size of the nozzle is calculated so that the liquid metal jet is suitable for inducing re-suspension of grains in a slurry region of a molten sump without altering a shape of the slurry region during steady state operation.
33 . The method of claim 30 , wherein determining the optimized casting parameter comprises ensuring at least one of the metal flow rate and the opening size of the nozzle is calculated so that the liquid metal jet has sufficient force to induce a crater in the molten sump, wherein the opening of the nozzle is sized such that the liquid metal jet produced induces a crater descent velocity of the crater having a variation of 10% or less from the casting speed during steady state operation.
34 . The method of claim 30 , wherein determining an optimized casting parameter comprises:
determining a mold Reynolds number using the mold dimensions and the casting speed; determining a jet Reynolds number using the mold Reynolds number; and calculating the optimized casting parameter 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 metal composition of the product being cast and determining the jet Reynolds number using the metal composition and the mold 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 fabricating the nozzle based on the opening size of the nozzle.
38 . The method of claim 30 , further comprising controlling a flow control device using the metal flow rate.
39 . The method of claim 30 , wherein determining the optimized casting parameter comprises ensuring at least one of the metal flow rate and the opening size of the nozzle is calculated so that the liquid metal jet has sufficient force to induce fluid flow within a molten sump sufficient to homogenize solute concentrations throughout the molten 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 process of casting a metal product comprising:
providing molten metal from a molten metal supply to a mold cavity through an opening of a nozzle at a flow rate during steady state operation, wherein providing molten metal through the opening of the nozzle at the flow rate includes producing a liquid metal jet in a molten sump sufficient to reduce macrosegregation in the metal product such that the metal product has a macrosegregation index at or below 0.100.
43 . The process of claim 42 , wherein the macrosegregation index is calculated according to:
Macrosegregation
Index
=
1
C
0
[
Y
A
dom
∫
∫
A
(
C
-
C
0
)
2
1
y
dA
]
1
/
2
wherein Y is a half thickness or a half diameter of the metal product, A dom is an area of a measured cross section of a measured point, y is a distance from a mid-thickness of the measured point, A is a delimiter indicating boundaries of integration over a cross section of the metal product, C 0 is a solute concentration of a target alloy composition, and C is a solute concentration at the measured point.
44 . The process of claim 42 , further comprising re-suspending grains in a slurry region of a molten sump, using the liquid metal jet, without altering a shape of the slurry region during steady state operation.
45 . The process of claim 44 , wherein the opening is sized such that the liquid metal jet has sufficient force to produce a crater in the slurry region and maintain a crater descent velocity within a 10% variation from a casting speed during steady state operation.
46 . The process of claim 42 , further comprising inducing fluid flow within a molten sump sufficient to homogenize solute concentrations throughout the molten sump.
47 . The process of claim 42 , wherein providing the molten metal through the nozzle at the flow rate further comprises controlling the flow rate using a flow control device coupled between the molten metal supply and the nozzle.
48 . The process of claim 42 , wherein the macrosegregation index is at or below 0.090.
49 . The process of claim 42 , wherein the macrosegregation index is at or below 0.070.Join the waitlist — get patent alerts
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