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University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab Claudio Ojeda 1 TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDS Claudio Ojeda Department of Mechanical Engineering University of Illinois at Urbana-Champaign October 15, 2002 Claudio Ojeda Department of Mechanical Engineering University of Illinois at Urbana-Champaign October 15, 2002

TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

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Page 1: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 1

TAPER PREDICTION IN SLAB AND THIN SLAB CASTING

MOLDS

Claudio Ojeda

Department of Mechanical EngineeringUniversity of Illinois at Urbana-Champaign

October 15, 2002

Claudio Ojeda

Department of Mechanical EngineeringUniversity of Illinois at Urbana-Champaign

October 15, 2002

Page 2: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 2

Introduction

Taper plays an important role to ensure good contact and heat exchange between mold wall and shell surface.– Shell growth uniformity

Problems– Excessive taper causes:

Narrow face wearing.

Extra tensile stress causes transverse cracking.Buckling of the shell wide face, causes “gutter” and longitudinal cracks.

– Insufficient taper causes:Breakouts in the steel shell.Bulging below mold causing subsurface longitudinal cracks.

Taper plays an important role to ensure good contact and heat exchange between mold wall and shell surface.– Shell growth uniformity

Problems– Excessive taper causes:

Narrow face wearing.

Extra tensile stress causes transverse cracking.Buckling of the shell wide face, causes “gutter” and longitudinal cracks.

– Insufficient taper causes:Breakouts in the steel shell.Bulging below mold causing subsurface longitudinal cracks.

Page 3: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 3

Objectives

Calculate ideal taper including the effects of:– Shell shrinkage– Mold distortion– Flux layer thickness– Funnel extra length (thin slabs)

Investigate the effect of heat flux profile on Ideal Taper in conventional and thin slabs as affected by

– Heat flux profile– Casting speed– Steel grade– Powder type– Mold length

Calculate ideal taper including the effects of:– Shell shrinkage– Mold distortion– Flux layer thickness– Funnel extra length (thin slabs)

Investigate the effect of heat flux profile on Ideal Taper in conventional and thin slabs as affected by

– Heat flux profile– Casting speed– Steel grade– Powder type– Mold length

Page 4: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 4

Model description

Finite difference heat transfer and solidification model (CON1D).2D Finite element elastic-viscoplastic thermal-stress model (CON2D).1D slice-domain representing the behavior of a longitudinal slice through the centerline of the shellmoving down the mold.Heat flux boundary condition is applied in the shell surface.

Finite difference heat transfer and solidification model (CON1D).2D Finite element elastic-viscoplastic thermal-stress model (CON2D).1D slice-domain representing the behavior of a longitudinal slice through the centerline of the shellmoving down the mold.Heat flux boundary condition is applied in the shell surface.

Page 5: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 5

Model description

Narrow faceNarrow face

WideWide

ShellShell

faceface

liquidliquidsteelsteel

LiquidsteelLiquidsteel

SolidifyingShellSolidifyingShell

Shell surfaceShell surface

InsulatedInsulated

Constant uAlong this edgeConstant uAlong this edge

tt

yy

xx

FF

qqxx

Page 6: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 6

Definition of ideal taper

Billet molds

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus)

Slab molds

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus)– (flux thickness(z) – flux thickness meniscus)

Thin slab molds

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus) – (flux thickness(z) – flux thickness meniscus) – (funnel extra length meniscus – funnel extra length(z))

Billet molds

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus)

Slab molds

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus)– (flux thickness(z) – flux thickness meniscus)

Thin slab molds

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus) – (flux thickness(z) – flux thickness meniscus) – (funnel extra length meniscus – funnel extra length(z))

Page 7: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 7

Billet Mold distortion

Billet casting operating conditions

Billet casting operating conditions Samarasekera, Brimacombe,

Ironmaking and Steel making, 1982, Vol. 9, Issue 1, pp 1-15

Samarasekera, Brimacombe, Ironmaking and Steel making, 1982, Vol. 9, Issue 1, pp 1-15

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DISTANCE BELOW MENISCUS (mm)

DIS

PL

AC

EM

EN

T(m

m)

0 100 200 300 400 500 600 700 800 900 1000-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Total shell shrinkage strainMold distortionIdeal Taper|

0.27%C, 1.0 m/min

Mold geometrySlab width 120 mm

Slab thickness 120 mm

Mold height 1100 mm

Cu plate thickness 10.15 mm

Copper propertiesThermal conductivity 360 W m-1K-1

Elastic modulus 117 GpaPoisson ratio 0.343Thermal expansion coefficient 16.0*10-6K-1

Density 8940 kg m-3

Operating conditionsPour temperature 1540 C

Water slot heat transfer coefficient 35 kW m-2K-1

Water temperature, Tw 30 C

Ambient temperature 25 CMeniscus level (below top mold) 100 mm

Page 8: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 8

Slab Mold distortion

Mold distortion = Wide face expansion + Narrow face distortion

– Wide face expansionTransmitted by clamping forcesLinearized temperatures of hot and cold plate faces

– Narrow face distortionLinearized temperatures of hot and cold plate facesWater jacket stiffness

Mold distortion = Wide face expansion + Narrow face distortion

– Wide face expansionTransmitted by clamping forcesLinearized temperatures of hot and cold plate faces

– Narrow face distortionLinearized temperatures of hot and cold plate facesWater jacket stiffness

+

−+

=∆

222hotcoldhotmencoldmen

moldWF

TTTTmoldwidthx α

( ) ( )[ ]2

12

__

3xLx

Kt

ttTT

xcold

coldhotcoldhotcoldhot

NF −+

−−

=∆αα

Page 9: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 9

Validation of Thin-slab mold distortion

Thin Slab operating conditionsThin Slab operating conditions Heat flux profile

1. Joong Kil Park, Brian G. Thomas, Indira V. Samarasekera, and U. Sok Yoon, Metallurgical and Materials Transactions B, 2002, vol. 33B, pp 425-436.

2. Joong Kil Park, Brian G. Thomas, Indira V. Samarasekera, and U. Sok Yoon, Metallurgical and Materials Transactions B, 2002, vol. 33B, pp 437-449.

Heat flux profile

1. Joong Kil Park, Brian G. Thomas, Indira V. Samarasekera, and U. Sok Yoon, Metallurgical and Materials Transactions B, 2002, vol. 33B, pp 425-436.

2. Joong Kil Park, Brian G. Thomas, Indira V. Samarasekera, and U. Sok Yoon, Metallurgical and Materials Transactions B, 2002, vol. 33B, pp 437-449.

Mold geometrySlab width 1260 mmSlab thickness 75 mmMold height 1000 mmCu plate thickness 60 mmWater slot depth – shallow slots 35 mmWater slot thickness 5 mmDistance between most slots 4.6 mm

Copper propertiesThermal conductivity 350 W m-1K-1

Elastic modulus 115 GpaPoisson ratio 0.34Thermal expansion coefficient 17.7*10-6K-1

Density 8960 kg m-3

Operating conditionsWater slot heat transfer coefficient 38.45 kW m-2K-1

Water temperature, Tw 37.8 C

Ambient temperature 35 CMeniscus level (below top mold) 100 mm

Page 10: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 10

Validation of Thin-slab Mold distortion

Wide face temperature Wide face expansionWide face temperature Wide face expansion

DISTANCE FROM TOP OF MOLD (mm)

WID

EF

AC

EE

XP

AN

SIO

N(m

m)

0 100 200 300 400 500 600 700 800 900 1000

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wide face expansion from Con1d resultsWide face expansion from 3D simulation

meniscus

DISTANCE BELOW TOP OF MOLD (mm)

TE

MP

ER

AT

UR

E(C

)

0 100 200 300 400 500 600 700 800 900 10000

100

200

300

400

500

600

Hot face temperatureCold face temperatureHot face linearized temperatureCold face linearized temperature

y = -0.269x + 444.17

y = -0.0495x + 116.57

meniscus

Thot

Tcold

Tref

Page 11: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 11

Validation conventional slab mold distortion

Conventional Slab operating cond.Conventional Slab operating cond. Heat flux profile

B.G.Thomas, G. Li, A. Moitra and D. Habing: ISS transactions, October 1998, pp 125-143.

Heat flux profile

B.G.Thomas, G. Li, A. Moitra and D. Habing: ISS transactions, October 1998, pp 125-143.

( )zq −−= 084.09.3168.2 0.0<z<0.084m

084.058.268.2 −−= zq 0.084<z<0.7m

Mold geometrySlab width 914 mmSlab thickness 220 mmMold height 700 mmCu plate thickness 60 mmWater slot depth – shallow slots 25 mmWater slot thickness 5 mmDistance between most slots 35 mm

Copper propertiesThermal conductivity 374 W m-1K-1

Elastic modulus 117 GpaPoisson ratio 0.343Thermal expansion coefficient 17.7*10-6K-1

Density 8940 kg m-3

Operating conditionsWater slot heat transfer coefficient 35 kW m-2K-1

Water temperature, Tw 15 C

Ambient temperature 35 CMeniscus level (below top mold) 84 mm

Page 12: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 12

Validation conventional slab mold distortion

Wide face temperature Narrow face temperatureWide face temperature Narrow face temperature

DISTANCE BELOW TOP OF THE MOLD (mm)

TE

MP

ER

AT

UR

E(C

)

0 100 200 300 400 500 600 7000

50

100

150

200

250

300

Hot face temperatureCold face temperatureLinearized hot face temperatureLinearized cold face temperature

y = -0.1678x + 220.98

y = -0.032x + 59.535

Thot

Tcold

meniscus

DISTANCE BELOW TOP OF THE MOLD (mm)

TE

MP

ER

AT

UR

E(C

)

0 100 200 300 400 500 600 7000

50

100

150

200

250

300

350

400

Hot face temperatureCold face temperatureLinearized hot face temperatureLinearized cold face temperature

y = -0.2489x + 320.42

y = -0.0769x + 95.16

Tcold

Thot

Tref

meniscus

Page 13: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 13

Validation conventional slab mold distortion

Wide face expansion + Narrow face distortionWide face expansion + Narrow face distortion

DISTANCE BELOW TOP OF THE MOLD (mm)

MO

LDD

IST

OR

TIO

N(m

m)

0 100 200 300 400 500 600 700-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

Narrow face distortion calculated in the 3D simulationAnalitical calculation of the mold distortion

meniscus

Page 14: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 14

Shell shrinkage

Heat flux profile– Importance of changes in meniscus area

Casting speed– Increasing casting speed increases instantaneous and average

heat flux but decreases time for shrinkage.

Mold length– For the same conditions higher mold length causes higher

shrinkage

Steel grade– Differences between low, peritectic and high carbon content

steels

Mold Powder composition– Differences in solidification temperature

Heat flux profile– Importance of changes in meniscus area

Casting speed– Increasing casting speed increases instantaneous and average

heat flux but decreases time for shrinkage.

Mold length– For the same conditions higher mold length causes higher

shrinkage

Steel grade– Differences between low, peritectic and high carbon content

steels

Mold Powder composition– Differences in solidification temperature

Page 15: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 15

Effect of heat flux profile

Shell shrinkage controlled by heat flux profile.Higher heat flux causes more shrinkage.Shell shrinkage sensitive to minor changes specially near the meniscus.Mean heat flux determined with*:

QG is the mean heat flux (MW/m2), µ is the powder viscosity at 1300 oC, (Pa-s), Tflow is the melting temperature of the mold flux (oC), Vc is the casting speed (m/min), and %C is the carbon content

– *C. Cicutti, M. Valdez and T. Perez, "Mould Thermal Evaluation in a Slab Continuous Casting Machine," 85th Steelmaking Conference, (Nashville, TE, USA), Iron and Steel Society, Inc. (USA), Vol. 85, 2002, 97-107.

Shell shrinkage controlled by heat flux profile.Higher heat flux causes more shrinkage.Shell shrinkage sensitive to minor changes specially near the meniscus.Mean heat flux determined with*:

QG is the mean heat flux (MW/m2), µ is the powder viscosity at 1300 oC, (Pa-s), Tflow is the melting temperature of the mold flux (oC), Vc is the casting speed (m/min), and %C is the carbon content

– *C. Cicutti, M. Valdez and T. Perez, "Mould Thermal Evaluation in a Slab Continuous Casting Machine," 85th Steelmaking Conference, (Nashville, TE, USA), Iron and Steel Society, Inc. (USA), Vol. 85, 2002, 97-107.

−−−⋅= −−

247.019.109.06

027.0

%107.0exp152.011063.4

CVTQ CflowG µ

Page 16: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 16

Effect of heat flux

DISTANCE BELOW MENISCUS (mm)

HE

AT

FLU

X(M

W/m

2)

0 100 200 300 400 500 600 700 8000

1

2

3

4

5

6

Higher Meniscus heat fluxHigher mold exit heat flux

Heat flux average = 1.466 MW/m20.08%C, 1.5 m/min

DISTANCE BELOW MENISCUS (mm)

SH

ELL

SH

RIN

KA

GE

(mm

)

0 100 200 300 400 500 600 700 8000

1

2

3

4

5

Higher meniscus heat fluxHigher mold exit heat flux

Heat Flux Average=1.466 MW/m20.08%C, 1.5 m/min

Page 17: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 17

Effect of casting speed

– Higher casting speed causes higher heat flux (more shrinkage) but less dwell time (less shrinkage).Net effect: less shrinkage

– Higher casting speed causes higher heat flux (more shrinkage) but less dwell time (less shrinkage).Net effect: less shrinkage

DISTANCE-BELOW-MENISCUS(mm)

SH

ELL

SU

RF

AC

ET

EM

PE

RA

TU

RE

(C)

0 100 200 300 400 500 600 700 800

1000

1100

1200

1300

1400

1500

1.1 m/min1.5 m/min1.9 m/min

0.07%C, Flux E

TIME BELOW MENISCUS (mm)

HE

AT

FL

UX

(MW

/m2)

0 10 20 30 40 50 600

1

2

3

4

5

6

7

High heat flux q=6.5(t+1)-0.5

Width: 200 mmWidth: 200 mm

Page 18: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 18

Effect of casting speed

DISTANCE-BELOW-MENISCUS(mm)

TO

TA

LS

HE

LLS

HR

INK

AG

ES

TR

AIN

(%)

0 100 200 300 400 500 600 700 8000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.1 m/min1.5 m/min1.9 m/min

0.07%C, Flux E

DISTANCE BELOW MENISCUS (mm)

SH

ELL

TH

ICK

NE

SS

(mm

)

0 100 200 300 400 500 600 700 8000

2

4

6

8

10

12

14

16

18

1.1 m/min1.5 m/min1.9 m/min

0.07%C, Flux E

Width: 200 mmWidth: 200 mmWidth: 200 mmWidth: 200 mm

Page 19: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 19

Effect of casting speed

Effect of casting speed on Ideal taperEffect of casting speed on Ideal taper

DISTANCE BELOW MENISCUS (mm)

IDE

AL

TA

PE

R(%

)

0 100 200 300 400 500 600 700 800-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.1 m/min1.5 m/min1.9 m/min

0.07%C, Flux E

Width: 200 mmWidth: 200 mm

Page 20: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 20

Effect of casting speed

Peritectic steels High carbon steelsPeritectic steels High carbon steels

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DISTANCE BELOW MENISCUS (mm)

IDE

AL

TA

PE

R(%

)

0 100 200 300 400 500 600 700 800-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0.27 % Carbon Content, 1.2 m/min Casting Speed0.27 % Carbon Content, 1.5 m/min Casting Speed0.47 % Carbon Content, 1.04 m/min Casting Speed0.47 % Carbon Content, 1.3 m/min Casting Speed|

||

|

|

||

| | | | ||

||

||

|

|

|

|

|

DISTANCE BELOW MENISCUS (mm)

IDE

AL

TA

PE

R(%

)

0 100 200 300 400 500 600 700 800-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0.13 % Carbon Content, 1.2 m/min Casting Speed0.13 % Carbon Content, 1.5 m/min Casting Speed0.16 % Carbon Content, 1.18 m/min Casting Speed0.16 % Carbon Content, 1.5 m/min Casting Speed|

Width: 200 mmWidth: 200 mmWidth: 200 mmWidth: 200 mm

Page 21: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 21

Effect of casting speed

Cases 0B 1B 2B 3B 4B 5B 6B 7B 8B 9B 10B 11B 12B

Grade peritectic medium carbon medium carbon high carbonTliquidus 1527 1521 1517 1490Carbon content 0.08% 0.13% 0.16% 0.27% 0.47%%Mn, %Si 0.42%, 0.01% .57%, .22% .87%, .14% .75%, .22%%P, %S .07%, .07% .07%, .07% .007%, .005% .018%, .007%Powder type E (220) E (220) C (666) C (666) E(220) E (220)Viscosity (Pa-s) 0.083 0.083 0.192 0.192 0.083 0.083sol. Temp ( C ) 1120 1120 1215 1215 1120 1120Casting Speed (m/min) 1.1 1.5 1.9 1.3 1.45 1.2 1.5 1.18 1.5 1.2 1.5 1.04 1.3Tundish temp (C) 1567 1555 1555 1559 1559 1542Heat Flux (MW/m2)Heat Average (MW/m2) 1.70 1.94 2.13 1.83 1.94 1.77 1.94 1.76 1.94 1.77 1.94 1.67 1.83Surf Temp (exit (C) 1016 1032 1044 1005 1010 1001 1012 1006 1018 1006 1018 972 984Shrinkage (mm) CON1D 13.18 12.36 11.74 8.98 8.68 8.30 7.84 11.03 10.47 8.64 8.16 8.09 7.17Shrinkage 50mm CON2D 2.40 1.84 1.41 2.47 2.27 2.87 2.47 2.36 1.96 1.94 1.56 1.81 1.46Shrinkage (mm) CON2D 6.80 6.29 5.92 6.98 6.81 7.42 7.08 6.79 6.44 6.29 5.96 6.05 5.73Taper (%/mold) CON2D 1.36 1.26 1.18 1.40 1.36 1.48 1.42 1.36 1.29 1.26 1.19 1.21 1.15Flux layer (mm) 1.47 1.25 1.14 1.39 1.33 2.34 2.07 2.23 1.91 1.99 1.76 1.99 1.76Mold distortion+expansion (mm) -0.43 -0.55 -0.65 -0.49 -0.55 -0.46 -0.55 -0.46 -0.55 -0.46 -0.55 -0.41 -0.49Ideal NF (mm) 5.70 5.60 5.45 6.05 6.05 5.55 5.55 5.00 5.10 4.75 4.75 4.50 4.45Ideal NF (%) 1.14 1.12 1.09 1.21 1.21 1.11 1.11 1.00 1.02 0.95 0.95 0.90 0.89

high carbon

.3%, .03%

.01%, .007%

low carbon15270.07%

Page 22: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 22

Effect of casting speed

Higher casting speed causes higher heat flux (more shrinkage) but less dwell time (less shrinkage).

Measured data of heat flux*Net effect: no change in shrinkage

*C. Cicutti, M. Valdez and T. Perez, "Mould Thermal Evaluation in a Slab Continuous Casting Machine," 85th Steelmaking Conference, (Nashville, TE, USA), Iron and Steel Society, Inc. (USA), Vol. 85, 2002, 97-107.

Higher casting speed causes higher heat flux (more shrinkage) but less dwell time (less shrinkage).

Measured data of heat flux*Net effect: no change in shrinkage

*C. Cicutti, M. Valdez and T. Perez, "Mould Thermal Evaluation in a Slab Continuous Casting Machine," 85th Steelmaking Conference, (Nashville, TE, USA), Iron and Steel Society, Inc. (USA), Vol. 85, 2002, 97-107.

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DISTANCE BELOW MENISCUS (mm)

HE

AT

FLU

X(M

W/m

2)

0 100 200 300 400 500 600 700 8000

1

2

3

4

5

6

7

8

0.07%C, 1.1 m/min, avg q: 1.39 MW/m2

0.07%C, 1.5 m/min, avg q: 1.61 MW/m2

0.07%C, 1.9 m/min, avg q: 1.8 MW/m2

0.08%C, 1.3 m/min, avg q: 1.48 MW/m2

0.08%C, 1.45 m/min, avg q: 1.56 MW/m2|

X

Flux ESlab width: 1000 mmSlab thickness: 200 mmWorking mold length: 800 mmPouring temperature: 1567oC

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TE

MP

ER

AT

UR

E(C

)

0 100 200 300 400 500 600 700 8001100

1150

1200

1250

1300

1350

1400

1450

1500

1550

Flux E, 0.07%C, 1.1 m/minFlux E, 0.07%C, 1.5 m/minFlux E, 0.07%C, 1.9 m/minFlux E, 0.08%C, 1.3 m/minFlux E, 0.08%C, 1.45 m/min

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DISTANCE-BELOW-MENISCUS(mm)

TO

TA

LS

HE

LLS

HR

INK

AG

ES

TR

AIN

(%)

0 100 200 300 400 500 600 700 8000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

Flux E, 0.07, 1.1 m/minFlux E, 0.07, 1.5 m/minFlux E, 0.07, 1.9 m/minFlux E, 0.08, 1.3 m/minFlux E, 0.08, 1.45 m/min

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Page 23: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 23

Effect of mold length

Mold length– For the same conditions (including heat flux), shell

shrinkage strains for different mold lengths can be approximated with the same curve

– Shell shrinkage for different mold lengths can be obtained truncating the curves at the desired working mold length

Mold length– For the same conditions (including heat flux), shell

shrinkage strains for different mold lengths can be approximated with the same curve

– Shell shrinkage for different mold lengths can be obtained truncating the curves at the desired working mold length

Page 24: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 24

Effect of mold length

DISTANCE-BELOW-MENISCUS(mm)

TO

TA

LS

HE

LLS

HR

INK

AG

ES

TR

AIN

(%)

0 100 200 300 400 500 600 700 8000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.1 m/min1.5 m/min1.9 m/min

0.07%C, Flux E

TIME BELOW MENISCUS (s)

HE

AT

FL

UX

(MW

/m2 )

0 10 20 30 40 50 600

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2

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4

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7

q=6.5(t+1)-0.5

Page 25: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 25

Effect of steel grade

Steel grade effectSteel grade effect Low carbon steels (>0.08%C)– Higher plastic strain– Higher thermal expansion

Peritectic steels ( 0.1%)– Deeper oscillation marks

causes lower heat flux– Higher thermal expansion– Final result the smallest shell

shrinkages

High carbon steels (>0.2%)– Shallow oscillation marks

Higher heat flux– Small inelastic strain

Thermal strain– Heat flux and shell shrinkage

similar to low carbon steels

Low carbon steels (>0.08%C)– Higher plastic strain– Higher thermal expansion

Peritectic steels ( 0.1%)– Deeper oscillation marks

causes lower heat flux– Higher thermal expansion– Final result the smallest shell

shrinkages

High carbon steels (>0.2%)– Shallow oscillation marks

Higher heat flux– Small inelastic strain

Thermal strain– Heat flux and shell shrinkage

similar to low carbon steelsTemperature (oC)

Th

erm

alL

inea

rE

xpan

sio

n(m

/m)

800 1000 1200 1400 1600-0.02

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.02

0.003%C0.044%C0.1%C0.27%C0.44%C

Reference Temperature = Solidus

Page 26: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 26

Effect of steel grade

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DISTANCE BELOW MENISCUS (mm)

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AT

FL

UX

(MW

/m2

)

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5

0.07%C, Flux E0.08%C, Flux E0.13%C, Flux C0.16%C, Flux C0.47%C, Flux E

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Casting speed: 1.5 m/min

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SH

EL

LS

UR

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CE

TE

MP

ER

AT

UR

E(C

)

0 100 200 300 400 500 600 700 8001100

1150

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1250

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1350

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1500

1550

0.07%C, Flux E0.08%C, Flux E0.13%C, Flux C0.16%C, Flux C0.47%C, Flux E

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Casting speed: 1.5 m/min

Page 27: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 27

Effect of steel grade

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DISTANCE-BELOW-MENISCUS(mm)

TO

TA

LS

HE

LLS

HR

INK

AG

ES

TR

AIN

(%)

0 100 200 300 400 500 600 700 8000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

0.07%C, Flux E0.08%C, Flux E0.13%C, Flux C0.16%C, Flux C0.47%C, Flux E

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X

Casting speed: 1.5 m/min

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DISTANCE BELOW MENISCUS (mm)

SH

ELL

TH

ICK

NE

SS

(mm

)

0 100 200 300 400 500 600 700 8000

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14

0.07%C, Flux E0.08%C, Flux E0.13%C, Flux C0.16%C, Flux C0.47%C, Flux E

|

X

Casting speed: 1.5 m/min

Page 28: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 28

Effect of steel grade

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X

DISTANCE BELOW MENISCUS (mm)

IDE

AL

TA

PE

R(%

)

0 100 200 300 400 500 600 700 800-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

0.07 %C, Flux E0.08 %C, Flux E0.13 %C, Flux C0.16 %C, Flux C0.47 %C, Flux E

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X

Casting speed: 1.5 m/min

CARBON CONTENT (%)

TO

TA

LS

HE

LLS

HR

INK

AG

ES

TR

AIN

(%)

0 0.1 0.2 0.3 0.4 0.50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

Powder E, meniscus to mold exitPowder C, meniscus to mold exitPowder E, 50 mm to mold exitPowder C, 50 mm to mold exit

Page 29: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 29

Effect of steel grade

Grade low carbon peritectic medium carbon medium carbon high carbonTliquidus 1527 1527 1521 1517 1490Carbon content 0.07% 0.08% 0.13% 0.16% 0.47%%Mn, %Si .3%, .03% 0.42%, 0.01% .57%, .22% .87%, .14% .75%, .22%%P, %S .01%, .007% .07%, .07% .07%, .07% .007%, .005% .018%, .007%Powder type E (220) E (220) C (666) C (666) E (220)viscosity (Pa-s) 0.083 0.083 0.192 0.192 0.083sol. Temp (C) 1120 1120 1215 1215 1120Flux comsumption rate (kg/t) 0.245 0.245 0.245 0.245 0.05Solid flux velocity ratio (V/Vc) 0.02 0.0185 0.0026 0.0091 0.009Oscilation mark depth (mm) 0.24 0.24 0.34 0.34 0.05Casting Speed (m/min) 1.5 1.5 1.5 1.5 1.5Tundish temp (C) 1567 1567 1567 1567 1567

Heat flux average (MW/m2) 1.61 1.59 1.29 1.37 1.64Surf Temp (exit (C) 1126.7 1134.3 1250.2 1218 1114.7Shrinkage (mm) CON1D 9.40 5.96 3.12 6.52 4.96Shrinkage 50mm CON2D 2.73 2.62 1.43 1.33 2.31Shrinkage (mm) CON2D 6.21 6.04 3.72 3.74 4.61Taper (%/mold) CON2D 1.24 1.21 0.74 0.75 0.92Flux layer (mm) 1.30 1.31 1.98 1.97 1.51Narrow face distortion (mm) -1.54 -1.51 -1.32 -1.35 -1.71Wide face expansion (mm) 1.07 1.06 0.96 1.01 1.45Ideal NF (mm) 5.37 5.19 2.09 2.11 3.36Ideal NF (%) 1.0737 1.037 0.418 0.421 0.672

Page 30: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 30

Effect of mold flux composition

Study of the effect of Powder composition in shell shrinkage– Mold powder viscosity

Slight changes in shell shrinkage

– Mold powder Solidification temperatureHigher solidification temperature causes a lower heat flux and consequently lower shell shrinkage

Study of the effect of Powder composition in shell shrinkage– Mold powder viscosity

Slight changes in shell shrinkage

– Mold powder Solidification temperatureHigher solidification temperature causes a lower heat flux and consequently lower shell shrinkage

Page 31: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 31

Effect of mold flux composition

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DISTANCE BELOW MENISCUS (mm)

IDE

AL

TA

PE

R(%

)

0 100 200 300 400 500 600 700 800-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

Flux solidification temperature: 1040oCFlux solidification temperature: 1120oCFlux solidification temperature: 1160oCFlux solidification temperature: 1215oC|

0.07%C, 1.5 m/min

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DISTANCE-BELOW-MENISCUS(mm)

TO

TA

LS

HE

LLS

HR

INK

AG

ES

TR

AIN

(%)

0 100 200 300 400 500 600 700 8000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

Flux solidification temperature: 1040oCFlux solidification temperature: 1120oCFlux solidification temperature: 1160oCFlux solidification temperature: 1215oC|

0.07%C, 1.5 m/min

Page 32: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 32

Effect of mold flux composition

Grade low carbonTliquidus 1527Carbon content 0.07%%Mn, %Si .3%, .03%%P, %S .01%, .007%Powder type A (RB1 - B) C (666) D (155) E (220)viscosity (Pa-s) 0.225 0.192 0.115 0.083sol. Temp (C) 1160 1215 1040 1120Flux comsumption rate (kg/t) 0.25 0.25 0.25 0.25Solid flux velocity ratio (V/Vc) 0.008 0.015 0.011 0.020Oscillation mark depth (mm) 0.24 0.24 0.24 0.24Casting Speed (m/min) 1.5 1.5 1.5 1.5Tundish temp (C) 1567 1567 1567 1567

Heat Flux average (MW/m2) 1.41 1.36 1.71 1.61Surf Temp (exit (C) 1202.1 1220 1090 1126.7Shrinkage (mm) CON1D 7.72 7.24 10.36 9.40Shrinkage 50 mm CON2D 2.12 1.88 3.08 2.73Shrinkage (mm) CON2D 4.98 4.64 6.82 6.21Taper (%/mold) CON2D 1.00 0.93 1.36 1.24Flux layer (mm) 1.59 1.73 1.12 1.30Narrow face distortion (mm) -1.36 -1.29 -1.65 -1.54Wide face expansion (mm) 0.94 0.88 1.17 1.07Ideal NF (mm) 3.81 3.32 6.15 5.37Ideal NF (%) 0.76 0.66 1.23 1.07

Page 33: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 33

Conclusions

More taper is needed near the top of the mold to compensate the more shrinkage of the steel shell.As casting speed increases, shrinkage decreases.Shell shrinkage depends mainly of the heat flux profile which depends of the casting speed and interface conditions.Peritectic steels generally requires smaller taper (due to the lower heat flux caused by bigger oscillation marks).Mold powders with higher solidification temperatures require less taper (due to lower heat flux).

More taper is needed near the top of the mold to compensate the more shrinkage of the steel shell.As casting speed increases, shrinkage decreases.Shell shrinkage depends mainly of the heat flux profile which depends of the casting speed and interface conditions.Peritectic steels generally requires smaller taper (due to the lower heat flux caused by bigger oscillation marks).Mold powders with higher solidification temperatures require less taper (due to lower heat flux).

Page 34: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 34

Extra length in Funnel

In thin slab casting there is a taper induced by the change in perimeter of the wide face, because of the funnel shape.

In thin slab casting there is a taper induced by the change in perimeter of the wide face, because of the funnel shape.

++= − a

ba

ab

b

baEL

221

22 2sin

22

Page 35: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 35

Extra length in funnel

Page 36: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 36

Thin slab casting ideal taper

Higher casting speeds than conventional slab casting.Funnel shape effect.

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus)– (flux thickness(z) – flux thickness meniscus) – (funnel extra length meniscus – funnel extra length(z))

Higher casting speeds than conventional slab casting.Funnel shape effect.

IT= Shell shrinkage(z) – (Mold distortion(z) – Mold distortion meniscus)– (flux thickness(z) – flux thickness meniscus) – (funnel extra length meniscus – funnel extra length(z))

Page 37: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 37

Thin slab casting conditions

Operating Conditions.Operating Conditions.

Mold geometrySlab thickness 49.78 mmMold Heigth 1100 mmCu plate thickness 121 mmFunnelFunnel width: a 1020 mmFunnel depth at top: b 60 mmFunnel heigth 750 mm

Description Carbon Content Casting Speed Mold Width Meniscus levelDifficult to cast low carbon 0.04% 4.5 m/min 1280 mm 83 mmLow Carbon 0.06% 4.7 m/min 1100 mm 83 mmApproximately Peritectic 0.074% 3.9 m/min 1020 mm 83 mmHigh Carbon 0.83% 4 m/min 1020 mm 58 mm

Page 38: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 38

Thin slab casting ideal taper

Heat flux and surface temperatures Heat flux and surface temperatures

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5

0.04% C, 4.5 m/min Casting speed, 1280 mm Mold Width0.055% C, 4.7 m/min Casting speed, 1105 mm Mold Width0.074% C, 3.9 m/min Casting speed, 1020 mm Mold Width0.83% C, 3.7 m/min Casting Speed, 1021 mm Mold Width|

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E(C

)

0 100 200 300 400 500 600 700 800 900 10001000

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1250

1300

1350

1400

1450

1500

1550

0.04% C, 4.5 m/min Casting Speed, 1020 mm Mold Width0.055% C, 4.7 m/min Casting Speed, 1105 mm Mold Width0.074% C, 3.9 m/min Casting Speed, 1020 mm Mold Width0.83% C, 3.7 m/min Casting Speed, 1021 mm Mold Width|

Page 39: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 39

Thin slab casting ideal taper

Solidified steel shell thicknessSolidified steel shell thickness

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DISTANCE BELOW MENISCUS (mm)

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0.04% C, 4.5 m/min, 1280 mm Mold Length0.055% C, 4.7 m/min, 1105 mm Mold Length0.074% C, 3.9 m/min, 1020 mm Mold Length0.83% C, 4.0 m/min, 1021 mm Mold Length|

Page 40: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 40

Thin slab casting ideal taper

Difficult to cast low carbonDifficult to cast low carbon

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DISTANCE BELOW MENISCUS (mm)

DIS

TA

NC

E(m

m)

0 100 200 300 400 500 600 700 800 900 1000-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

Steel shell shrinkageMold narrow face distortionMold flux layer thicknessFunnel extra lengthIdeal Taper|

0.04% Carbon Content, 4.5 m/min Casting Speed1280 mm Mold Width

Page 41: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 41

Thin slab casting ideal taper

Common low carbon steelCommon low carbon steel

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DISTANCE BELOW MENISCUS (mm)

DIS

TA

NC

E(m

m)

0 100 200 300 400 500 600 700 800 900 1000-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

Steel shell shrinkagemold narrow face distortionMold flux layer thicknessFunnel extra lengthIdeal Taper|

0.055 % Carbon Content, 4.7 m/min Casting Speed1100 mm Mold Width

Page 42: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 42

Thin slab casting ideal taper

Approximately peritectic steelApproximately peritectic steel

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DISTANCE BELOW MENISCUS (mm)

DIS

TA

NC

E(m

m)

0 100 200 300 400 500 600 700 800 900 1000-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

Steel shell shrinkageMold narrow face distortionMold flux layer thicknessFunnel extra lengthIdeal Taper|

0.074% Carbon Content, 3.9 m/min Casting Speed1020 mm Mold Width

Page 43: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 43

Thin slab casting ideal taper

High carbon steelHigh carbon steel

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DISTANCE BELOW MENISCUS (mm)

DIS

TA

NC

E(m

m)

0 100 200 300 400 500 600 700 800 900 1000-3.5

-3-2.5

-2-1.5

-1-0.5

00.5

11.5

22.5

33.5

44.5

55.5

6

Steel shell shrinkageMold distortionMold flux layer thicknessEnter-XY DataIdeal Taper|

0.83% Carbon Content, 3.7 m/min Casting Speed1020 mm Mold Width

Page 44: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 44

Thin slab casting ideal taper

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DISTANCE BELOW MENISCUS (mm)

IDE

AL

TA

PE

R(%

)

0 100 200 300 400 500 600 700 800 900 1000-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.04%C, 4.5 m/min0.055%C, 4.7 m/min0.074%C, 3.9 m/min0.83%C, 3.7 m/min|

Page 45: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 45

Thin slab casting ideal taper

ResultsResults

1.2

0.95

0.95

0.85

Taper used currently (%/mould)

-0.42

-0.01

0.0

0.23

Suggested Taper from Calculations (%/mold)

21497.9823107.880.83

21528.6721777.220.074

23559.7923108.330.055

23469.442732.4811.660.04

Computed Heat Flux (kW/m2)

Computed T (°C)

Recorded Heat Flux (kW/m2)

Recorded T (°C)

Case (carbon content %)

Page 46: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 46

Thin slab casting ideal taper

Results– The shell shrinks more on the top of the mold than in

the bottom of the mold, so it is difficult to match the shrinkage of the shell shell with a linear Taper.

– Mold distortion, flux layer thickness and extra length of funnel significantly affect the Ideal taper.

– The Ideal Taper predicted is for all cases smaller than the taper used currently.

Results– The shell shrinks more on the top of the mold than in

the bottom of the mold, so it is difficult to match the shrinkage of the shell shell with a linear Taper.

– Mold distortion, flux layer thickness and extra length of funnel significantly affect the Ideal taper.

– The Ideal Taper predicted is for all cases smaller than the taper used currently.

Page 47: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 47

Effect of ferrostatic pressure

DISTANCE-BELOW-MENISCUS(mm)

TO

TA

LS

HE

LL

SH

RIN

KA

GE

ST

RA

IN(%

)

0 100 200 300 400 500 600 700 800 900 10000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

Without ferrostatic pressureWidth: 120 mm with Ferrostatic pressureWidth: 200 mm with ferrostatic pressure

Page 48: TAPER PREDICTION IN SLAB AND THIN SLAB CASTING MOLDSccc.illinois.edu/s/2002_Presentations/CCC_Claudio_2002.pdfc is the casting speed (m/min), and %C is the carbon content – *C. Cicutti,

University of Illinois at Urbana-Champaign • Metals Processing Simulation Lab • Claudio Ojeda 48

Conclusions

More taper is needed near the top of the mold, such as achieved using parabolic taper.As casting speed increases, shrinkage decreases (for same conditions and heat flux profile).Mold length affects the taper only by extending the nonlinear curve (for the same conditions and heat flux profile).Mold taper depends mainly on the heat flux profile, which in turn depends on the casting speed and interface conditions (powder, steel grade, etc.). Peritectic steels generally require slightly less taper than either low or high carbon steels, owing to their lower heat flux.Mold powders with higher solidification temperature have lower heat flux (compared with both oil lubrication or low solidification temperature powders) and consequently have less shrinkage and less ideal taper (other conditions staying the same).Flux layer thickness, mold distortion and extra length of funnel (thin slabs) make important contributions to Ideal Taper.

More taper is needed near the top of the mold, such as achieved using parabolic taper.As casting speed increases, shrinkage decreases (for same conditions and heat flux profile).Mold length affects the taper only by extending the nonlinear curve (for the same conditions and heat flux profile).Mold taper depends mainly on the heat flux profile, which in turn depends on the casting speed and interface conditions (powder, steel grade, etc.). Peritectic steels generally require slightly less taper than either low or high carbon steels, owing to their lower heat flux.Mold powders with higher solidification temperature have lower heat flux (compared with both oil lubrication or low solidification temperature powders) and consequently have less shrinkage and less ideal taper (other conditions staying the same).Flux layer thickness, mold distortion and extra length of funnel (thin slabs) make important contributions to Ideal Taper.