Cast Steel Research · 2020. 7. 24. · Steel Casting Capability -Unique capability: melting high...
Transcript of Cast Steel Research · 2020. 7. 24. · Steel Casting Capability -Unique capability: melting high...
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Cast Steel Research
V. Richards and S. Lekakh
Missouri S & T
October 29, 2012
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Steel Casting Capability
- Unique capability: melting high quality
complex alloys, high purity steels (alone
among US Universities)
- Diverse molding capability (green sand, no-
bake, ceramic investment, ingot molds)
- Advanced instrumentation: temperature,
active oxygen, chemistry, LECO (C, S, N, O),
thermal analysis
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Projects overview
Liquid and solidified steel
Solidification kinetics
- thermal analysis
- thermodynamic modeling (FACTSAGE)
Fluidity phenomena and mold filling
- electric sensing of fill
- CFD (Fluent, Magma) modeling
Metal-mold interactions
- Ceramic molds
- Burn-in defects in sand molds
High temperature thermal properties of mold materials
- physical measurements
- inverse modeling
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Solidification of high strength cast steel
Thermal probe with low Biot number Bi=hL/k
Important steel solidification parameters:
Tliq and Tsol
Fraction solid versus T
Dendrite coherency point
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Solid fraction versus temperature is
significantly different as peritectic is
shifted
0.0
0.2
0.4
0.6
0.8
1.0
1450 1470 1490 1510 1530
So
lid
fra
cti
on
Temperature, ⁰C
Heat 1 (base)
Heat 2 (3% Ni)
Heat 3 (5% Ni)
Heat 4 (9% Ni)
Heat 5 (9% Ni, 3.5% Cu)
Fe(L)+FCC
Thermodynamic approach
using Factsage
Austenite Stabilizers Shift Peritectic
Use of low Biot number mold to analyze casting properties near a peritectic
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Modeling confirmed with experimental approaches
Electric sensor
0
5
10
15
20
25
30
35
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45
0 2 4 6 8 10
Fil
l len
gth
, cm
Ni content, wt%
20C(exp)20C(model)60C(exp)60C(model)80C(exp)80C(model)
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Modeling combined with experimental verification using
electrical sensing and DAQ Calculated (Magma) and measured mold filling
2.40-2.50
2.30-2.40
2.20-2.30
2.10-2.20
2.00-2.10
1.90-2.00
1.80-1.90
1.70-1.80
1.60-1.70
1.50-1.60
1.40-1.50
1.30-1.40
1.20-1.30
1.10-1.20
1.00-1.10
0.90-1.00
0.80-0.90
0.70-0.80
3.20-3.30
3.10-3.20
3.00-3.10
2.90-3.00
2.80-2.90
2.70-2.80
2.60-2.70
2.50-2.60
2.40-2.50
2.30-2.40
2.20-2.30
2.10-2.20
2.00-2.10
1.90-2.00
1.80-1.90
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Solidification properties data MST generated enabled
modeling to solve casting problems with new steel alloys
Gas pressure Velocity Temperature
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Ceramic mold/steel melt interactions
Thermal condition:
- mold T exceeds Tliquidus
Thermo-chemical conditions:
- melt oxidation followed by
reaction with ceramic mold
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0.2
0.4
0.6
0.8
1
800 1000 1200 1400 1600
Fra
cti
on
Temperature, 0C
Liquid slag
MeSiO3
Cristobalite +Mullite
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Burn-in defects in sand molds
B
Quality of sand supporting wash is critical. Residual binder in mechanical
reclaim carries fluxing oxides. Loss of wash support
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High temperature thermal properties of mold materials
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800
1000
1200
1400
1600
0 200 400 600 800
Te
mp
era
ture
, 0C
Time, sec
Tcasting calTshell calTcasting exp
Tshell exp
High T thermal conductivity - novel laser flash method
Inverse experimental/modeling method
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Potential Applications
• Solidification properties of new steels
– Effect of Austenite stabilizers (Ni, Mn,?)
– Critical temperatures-Tliq, Tsol,
– Fraction solid versus temperature
– Dendrite coherency point
• Casting sound plates/ingots for subsequent
processing (rolling, heat treatment)
• Full suite of processes after casting
• Thermal analysis of mold
powders/fluxes/coatings effects on heat transfer