ferrous applications ii - polytechnique montréal · refractory dissolution in molten slag (rh...
TRANSCRIPT
Ferrous Applications II 1
Ferrous Applications II
Ferrous Applications II 2
Contents
Application examples Slide #
Slag liquidus temperature changing with an additional slag component 3
Dissolution mechanism of inclusions into molten slag 11
Non-metallic inclusion formation: oxide metallurgy 14
Inclusion control in Mn/Si killed steel 18
Reoxidation of steel - inclusion modification 27
Deoxidation diagram / Inclusion stability diagram 39
Inclusion in Al-killed Ti-bearing steel 45
Refractory dissolution in molten slag (RH degasser) 57
Ladle glaze formation 62
Thermal stability of refractory 65
Refractory / Liquid inclusion interaction 69
Refractory / Steel interaction 73
Desulfurization of hot metal and sulfide capacity calculation 79
Heat evolution during slag cooling and heating: Enthalpy diagram 132
New private compound database 140
Addition of ideal solution (private solution) 144
Addition of new component into slag (Henrian solution) 147
V2O3 addition to liquid slag (Henrian solution: optimization of parameter) 152
Zn galvanization: control of oxidation in annealing furnace 164
Zn galvanization: - remelting and oxidation of Zn galvanized steel
- interface reaction between liquid Zn and solid steel
- oxidation reaction of Zn coating
179
Carburization and de-carburization of steel 185
Viscosity of slags: Einstein-Roscoe equation for semi-liquid state 190
Ferrous Applications II 3
The effect of SiO2/MgO and FeO and Al2O3 in
slag on the liquidus temperature of the slag Phase Diagram / Equilib
Ferrous Applications II 4
Phase diagram of SiO2-MgO-Al2O3-FeO-Fe
Actually, the SiO2/MgO ratio of laterite is almost same as that of the slag
produced
The main system of the FToxid-SLAG phase is SiO2-MgO-Al2O3-FeO
Fe-saturation condition
Ferrous Applications II 5
Phase diagram of SiO2-MgO-Al2O3-FeO-Fe
Select pure solid and liquid Fe
for Fe-saturation condition
Ferrous Applications II 6
Phase diagram of SiO2-MgO-Al2O3-FeO-Fe
Ferrous Applications II 7
Ternary phase diagram
of FeO-MgO-SiO2
at constant Al2O3
with Fe-saturation
Add small
amount of Fe
Phase diagram of SiO2-MgO-Al2O3-FeO-Fe
Ferrous Applications II 8
Using
‘superimpose’
function,
liquidus lines of
the ternary
system can be
drawn.
Phase diagram of SiO2-MgO-Al2O3-FeO-Fe
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.10.20.30.40.50.60.70.80.9
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
SiO2
MgO FeOmass fractions /(SiO2+FeO+MgO)
SiO2
MgO FeOmass fractions /(SiO2+FeO+MgO)
ASlag-liq + Fe(s)
ASlag-liq + AOlivine + Fe(s)
ASlag-liq + Fe(s) + SiO2(s6)
ASlag-liq + AMonoxide + Fe(s)
ASlag-liq + AMonoxide + AOlivine + Fe(s)
SiO2
MgO FeOmass fractions /(SiO2+FeO+MgO)
SiO2
MgO FeOmass fractions /(SiO2+FeO+MgO)
SiO2
MgO FeOmass fractions /(SiO2+FeO+MgO)
1500 o
C1600 o
C1700 o
C1800 o
C
SiO2/MgO = 1
SiO2/MgO = 2
SiO2/MgO = 3
SiO2/MgO = 4
SiO2 - FeO - MgO - Al2O3 - FeAl
2O
3/Z (g/g) = 0, Fe/Z (g/g) = 0.00001,
Z=(SiO2+FeO+MgO),
Impossible to use ‘O’
option because the system
always has Fe(s) or Fe(I)
with slag, that is always
more than 2 phases
Ferrous Applications II 9
Phase diagram of SiO2-MgO-Al2O3-FeO-Fe
With varying 0 to 8 wt% of
Al2O3 at constant
SiO2/MgO=1
at Fe-saturation
Ferrous Applications II 10
Phase diagram of SiO2-MgO-Al2O3-FeO-Fe
Al2O3 = 0 wt%
Al2O3 = 3 wt%
Al2O3 = 8 wt%
SiO2 - MgO - Al2O3 - FeO - FeSiO
2-1MgO/Z (g/g) = 0, 100Al
2O
3/Z (g/g) = 0, 100Fe/Z (g/g) = 1,
Z=(SiO2+MgO+Al
2O
3+FeO+Fe), 1 atm
100FeO/(SiO2+MgO+Al2O3+FeO+Fe) (g/g)
T(C
)
0 10 20 30 40 50 60 70 80
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
Ferrous Applications II 11
Dissolution of Inclusions into Molten Slags
A l
M 1 M 3M 2 4M 2 3M 2 2M 2 1
C P
C a
M g
S i
Park, Jung and Lee: ISIJ Inter. No. 11, 2006
Phase diagram between slag and inclusions to understand the
inclusion dissolution mechanism
Ferrous Applications II 12
Dissolution of Inclusions into Molten Slags
10
20
30
40
50
60
70
80
90
102030405060708090
10
20
30
40
50
60
70
80
90
(CaO)0.525(SiO2)0.475
Al2O3 MgOweight percent
M24L+MgO
L+MgAl2O4+MgO
L+MgAl2O4
MgAl2O4
M23
M22
M21
M 2 2M 2 1M 1
M 3M 2 4M 2 3
F ig .8
M23
Park, Jung and Lee: ISIJ Inter. No. 11, 2006
Ferrous Applications II 13
Dissolution of Inclusions into Molten Slags
M 2 2M 2 1M 1
M 3M 2 4M 2 3
F ig .8
M3
10
20
30
40
50
60
70
80
90
102030405060708090
10
20
30
40
50
60
70
80
90
(CaO)0.58(SiO2)0.42
Al2O3 MgOweight percent
L + MgO + MgAl2O4
L + MgAl2O4
L + Ca2SiO4
L + MgO
MgAl2O4
M3
Park, Jung and Lee: ISIJ Inter. No. 11, 2006
Ferrous Applications II 14
- Evolution of non-metallic inclusions: Formation of acicular ferrite -
• Non-metallic inclusions: nucleation sites for acicular ferrite
• Acicular ferrite: enhances the strength of steel
Applications to oxide metallurgy (Inclusion control)
Ferrous Applications II 15
Evolution of Non-metallic Inclusions
Morphologies of typical inclusions found in Fe-C-Mn-Si-O-S-Ti-Mg-Al-N
M n /S i
M n /S i
+ T i
M n /S i
/T i
+ M g
M n /S i
/T i/M g
+ A l
M n S
M g -T i-A l-O
M g O
1㎛
M g -T i- (A l) -OM n S
M g O
1㎛
M n S
M g -A l- (T i) -O
M g O
2㎛
M g O
M g A l2O
4
M n
S
1㎛
M g A l2O
4M n S
1㎛
T i-M g -M n -O
M n S 2㎛
M n SM g -T i-M n -O
1㎛ 1㎛
M g -T i-M n -O
M n S
M g O
M g O
M n S
M g O
1㎛
2㎛
M n -S i-O
M n S
2㎛
M n -T i-O
M n -S i-O
M n S2㎛
M n -T i-O
M n -S i-O
M n S 1㎛
T i-M n -O
M n S1㎛
T i-O
M n S
(a )
( f ) (h ) ( i)
( j) (k ) ( l) (m ) (n )
C o n c e n tr a t io n o f a d d it io n a l a llo y in g e le m e n t
(d )(b ) (c ) (e )
(g )
M n /S i
M n /S i
+ T i
M n /S i
/T i
+ M g
M n /S i
/T i/M g
+ A l
M n S
M g -T i-A l-O
M g O
1㎛
M g -T i- (A l) -OM n S
M g O
1㎛
M n S
M g -A l- (T i) -O
M g O
2㎛
M n S
M g -A l- (T i) -O
M g O
2㎛
M g O
M g A l2O
4
M n
S
1㎛
M g A l2O
4M n S
1㎛
T i-M g -M n -O
M n S 2㎛
T i-M g -M n -O
M n S 2㎛
M n SM g -T i-M n -O
1㎛
M n SM g -T i-M n -O
1㎛ 1㎛
M g -T i-M n -O
M n S
M g O
1㎛
M g -T i-M n -O
M n S
M g O
M g O
M n S
M g O
1㎛
M g O
M n S
M g O
1㎛
2㎛
M n -S i-O
M n S
2㎛
M n -S i-O
M n S
2㎛
M n -T i-O
M n -S i-O
M n S2㎛
M n -T i-O
M n -S i-O
M n S 1㎛
T i-M n -O
M n S1㎛
T i-O
M n S
(a )
( f ) (h ) ( i)
( j) (k ) ( l) (m ) (n )
C o n c e n tr a t io n o f a d d it io n a l a llo y in g e le m e n t
(d )(b ) (c ) (e )
(g )
Fe-0.1C-0.0035S-1.45Mn-0.1Si
-0.015Ti-0.0025O-0.03N+Mg
Ferrous Applications II 16
Evolution of Non-metallic Inclusions
(PB) (IL)
(MgO/Sp) (Sp)
(MgO)
Mg=2ppm 4
16
52
35
Thermodynamic calculations
• Accurate prediction of inclusion phases
• Application to high strength steel design
Ferrous Applications II 17
Inclusion evolution with temperature: Mn/Si/Ti steel
MS-c
SLAGA#1
SLAGA#1
SLAGA#1
ILMEA#1
ILMEA#1
Rhod
OlivA
PSEU
98.2769 Fe + 0.1 C + 1.5 Mn + 0.1 Si +
c:\Workshop\Equi0.res 3May11
T(C)
wt
pp
m
1000 1100 1200 1300 1400 1500 1600
0
100
200
300
400
500
600
Select all phases (pure solids and
solutions) with amount > 0
FToxid : oxide inclusions
FTmisc: FeLq, MnS solid (MS_c)
FSStel: solid steel phases (fcc, bcc)
Ferrous Applications II 18
Wire
Inclusion (ex., alumina)
Crack Initiation
• Undeformable inclusion should be removed
• Liquid phase is desirable at process
temperature (~1200oC)
Application to Tire-Cord Steel (Mn/Si deoxidation)
Tire-Cord Steel
Thin Sheet
Inclusion (ex., alumina)
Crack Initiation
Surface Quality Fe-36%Ni Invar Steel
0.15~0.38mm diameter
150µm thickness
Mn/Si Deoxidation
Ferrous Applications II 19
MnO-Al2O3-SiO2 Phase Diagram
Target inclusion
composition
M n O A l2O
3
W e ig h t %
1 8 9 0
1 1 9 4
1 2 4 9
1 2 3 9
1 5 2 7
1 5 9 5
1 1 8 0
1 1 5 6
1 1 3 5
1 1 1 9
1 4 6 5
1 1 4 3
1 1 6 6
1 3 2 8
1 2 5 1
1 2 9 3
1 4 6 5
M n 2S iO 4
M n S iO 3
M n A l2O 4
A l6S i2O 1 3
M n 2A l4S i5O 1 8
M n 3A l2S i3O 1 2
C o ru n d u m
18
00
1 7 0 0
1 6 0 0
1 5 0 0
1 4 0 0
1 3 0 0
2 0 0 0
19
00
18
001
70
016
00
15
00
1 4 0 0
1 3 0 0
12
00
14
00
13
00
G a la x ite
M a n g a n o s ite
2 L iq u id s
M u llite
R h o d o n ite
T e p h ro ite
1 7 6 9
1 7 0 2
1 7 0 2
(1 7 2 3 )
(2 0 5 4 )(1 8 4 2 )
1600
T r id ym ite
S p e ssa r t it e
(1 8 9 0 )(1 3 4 7 )
M n O /S iO2 = 0 .5
M n O /S iO2 = 1 .0
M n O /S iO2 = 2 .0
1 1 5 0
S iO2
L o w l iq u id u s
te m p e r a tu r e r e g io n
(1 1 0 0o
C ~ 1 2 0 0o
C )
Cr is
tob a l i t
e
C ris to b a lite : S iO 2
T rid ym ite : S iO 2
R h o d o n ite : M n S iO 3
S p e ssa rt ite : M n 3 A l2 S i3 O 1 2
T e p h ro ite : M n 2 S iO 4
M a n g a n o s ite : M n O
G a la x ite : M n A l2 O 4
C o ru n d u m : A l2 O 3
M u llite : A l6 S i2 O 1 3
M n O A l2O
3
W e ig h t %
1 8 9 0
1 1 9 4
1 2 4 9
1 2 3 9
1 5 2 7
1 5 9 5
1 1 8 0
1 1 5 6
1 1 3 5
1 1 1 9
1 4 6 5
1 1 4 3
1 1 6 6
1 3 2 8
1 2 5 1
1 2 9 3
1 4 6 5
M n 2S iO 4
M n S iO 3
M n A l2O 4
A l6S i2O 1 3
M n 2A l4S i5O 1 8
M n 3A l2S i3O 1 2
C o ru n d u m
18
00
1 7 0 0
1 6 0 0
1 5 0 0
1 4 0 0
1 3 0 0
2 0 0 0
19
00
18
001
70
016
00
15
00
1 4 0 0
1 3 0 0
12
00
14
00
13
00
G a la x ite
M a n g a n o s ite
2 L iq u id s
M u llite
R h o d o n ite
T e p h ro ite
1 7 6 9
1 7 0 2
1 7 0 2
(1 7 2 3 )
(2 0 5 4 )(1 8 4 2 )
1600
T r id ym ite
S p e ssa r t it e
(1 8 9 0 )(1 3 4 7 )
M n O /S iO2 = 0 .5
M n O /S iO2 = 1 .0
M n O /S iO2 = 2 .0
1 1 5 0
S iO2
L o w l iq u id u s
te m p e r a tu r e r e g io n
(1 1 0 0o
C ~ 1 2 0 0o
C )
Cr is
tob a l i t
e
C ris to b a lite : S iO 2
T rid ym ite : S iO 2
R h o d o n ite : M n S iO 3
S p e ssa rt ite : M n 3 A l2 S i3 O 1 2
T e p h ro ite : M n 2 S iO 4
M a n g a n o s ite : M n O
G a la x ite : M n A l2 O 4
C o ru n d u m : A l2 O 3
M u llite : A l6 S i2 O 1 3
Jung et al., Metall. Mater. Trans. B, 2004, vol. 35B, pp. 259-268
Ferrous Applications II 20
Inclusion composition with steel composition
Jung et al., Metall. Mater. Trans. B, 2004, vol. 35B, pp. 259-268
Kang and Lee, ISIJ Inter., 2004.
10
20
30
40
50
60
70
80
90
102030405060708090
10
20
30
40
50
60
70
80
90
SiO2
MnO Al2O3Weight %
wt%Mn / wt%Si = 9
10
52
1
0.5
0.2
0.1
wt%Mn / wt%Si = 1
wt%Mn / wt%Si = 0.1
T =1550oC
Liquid Oxide
L + MnO L + MnAl2O4
L + Al2O3
L + Mullite
L + SiO2
MnO/SiO2 = 1.0
Mn + Si = 1wt%
Ferrous Applications II 21
Inclusion calculation in Mn/Si deoxidation
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.10.20.30.40.50.60.70.80.9
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
SiO2
MnO Al2O3mass fraction
ASlag-liq + AMonoxide ASlag-liq + MnAl2O4(s)
ASlag-liq + M2O3(corundum)
ASlag-liq + Mullite
ASlag-liq + SiO2(s6)
MnO - Al2O3 - SiO2
1600oC
Ferrous Applications II 22
Inclusion calculation in Mn/Si deoxidation
Calculation of the inclusion trajectory using Equilib
The compositions of Mn and Si are set based on the target Mn/Si ratio and Mn+Si content
Oxygen content should be controlled reasonably. If O is too high, Mn and Si will be largely
changed from original target composition after reaction with oxygen.
Ferrous Applications II 23
Inclusion calculation in Mn/Si deoxidation
Mn + Si + Al + O (Mn,Si,Al) oxide inclusion
After deoxidation, Mn ~ 0.5 and Si ~ 0.5
(Target steel composition: Mn/Si = 1 and Mn+Si = 1)
Extraction of slag composition
Ferrous Applications II 24
Inclusion calculation in Mn/Si deoxidation
Slag #1
(stable slag) Slag #2
(metastable or same as #1
except in case of stable miscibility gap)
Composition from Slag #1
A corner = wt%SiO2/100
B corner = (wt%MnO+Mn2O3+FeO+Fe2O3)/100
C corner = wt%Al2O3/100
Ferrous Applications II 25
Inclusion calculation in Mn/Si deoxidation
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.10.20.30.40.50.60.70.80.9
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
SiO2
MnO Al2O3mass fraction
ASlag-liq + AMonoxide ASlag-liq + MnAl2O4(s)
ASlag-liq + M2O3(corundum)
ASlag-liq + Mullite
ASlag-liq + SiO2(s6)
MnO - Al2O3 - SiO2
1600oC
10
20
30
40
50
60
70
80
90
102030405060708090
10
20
30
40
50
60
70
80
90
SiO2
Al2O3
Mn/Si = 10
5.0
2.01.0
0.5
Fe Liquid
[%Mn] + [%Si] = ~1.0
T = 1600oC
1.0
Kang and Lee [35]
SiO2
Al2O3
1200oC
liquidus
SiO2
MnO(+FeO) Al2O3
0.2
0.1
0.35
0.52
1.1
0.50
11.1
9.9
Ohta and Suito[34]
weight percent
Slag composition is slightly
different from phase diagram
because the actual slag contain
FetO and Mn2O3 as well.
According to calculations,
mullite and Al2O3 form
subsequently after slag
Ferrous Applications II 26
Inclusion calculation in Mn/Si deoxidation
Al2O3(SLAGA#1)
SiO2(SLAGA#1)
FeO(SLAGA#1)
Fe2O3(SLAGA#1)
MnO(SLAGA#1)
98.995 Fe + 0.5 Mn + 0.5 Si + <A> Al +
c:\Workshop\Equi0.res 3May11
weight % Al_FeLQ
we
igh
t %
0 0.0002 0.0004 0.0006 0.0008 0.001
0
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
Soluble Al vs. inclusion composition
Ferrous Applications II 27
Re-oxidation and inclusion modification in the tundish – Ca-treated steel
Ferrous Applications II 28
Reoxidation and inclusion modification in the tundish
The target for Ca treatment
Ferrous Applications II 29
Al-killed steel
Fe+100ppm O
MgO based refractory
+?Mg
+ 600ppm Al
At 1550oC
Reoxidation and inclusion modification in the tundish
+ <50ppm Ca + <100ppm SiO2
+? inclusion
+ ? Inclusion + ? Slag
Reoxidation: assuming mainly due to SiO2-based slag
+ ? Inclusion + ? Slag
Ca treatment: liquid slag
`
Ferrous Applications II 30
Reoxidation and inclusion modification in the tundish
Al-killed steel
Fe+100ppm O
MgO-based refractory
+?Mg
Ferrous Applications II 31
Only save liquid Fe as stream file for next step
MgO-based refractory
Reoxidation and inclusion modification in the tundish
Ferrous Applications II 32
+ 600ppm Al
+? inclusion
Al-killed steel
Reoxidation and inclusion modification in the tundish
Ferrous Applications II 33
Save all phases as a stream file for next step Alumina inclusions cause nozzle clogging
Formation of spinel phase
Reoxidation and inclusion modification in the tundish
Ferrous Applications II 34
+ <100ppm Ca
+ ? Inclusion + ? Slag
Ca treatment: liquid slag
Reoxidation and inclusion modification in the tundish
Ferrous Applications II 35
Reoxidation and inclusion modification in the tundish
Ferrous Applications II 36
+ <100ppm SiO2
Reoxidation: assuming mainly due to SiO2-based slag
+ ? Inclusion + ? Slag
`
Reoxidation and inclusion modification in the tundish
Ferrous Applications II 37
Reoxidation and inclusion modification in the tundish
CaAl4O7
In this condition,
SiO2 is reduced by Al during the reoxidation (instead of Ca).
Ferrous Applications II 38
Slag composition after Ca treatment (30 ppm Ca)
Reoxidation direction
Reoxidation and inclusion modification in the tundish
Ferrous Applications II 39
Inclusion diagram: Fe-Al-O, Al deoxidation
(1): draw rectangular diagram
Ferrous Applications II 40
Inclusion diagram: Fe-Al-O, Al deoxidation
(2): change X- and Y-axis lower limit.
(3): change linear scale to log scale.
(3): change linear scale to log scale.
(2): change X- and Y-axis lower limit.
“After changing the axes to log
scale, move all curves to +2 in
linear scale“
Ferrous Applications II 41
Inclusion diagram: Fe-Al-O, Al deoxidation
Fe-liq + M2O3(Corundum)
Fe-liq
Fe - Al - O
1600oC
log [wt% Al]
log
[w
t% O
]
-4 -3.5 -3 -2.5 -2 -1.5 -1 -.5 0
-4
-3.5
-3
-2.5
-2
-1.5
-1(4) Editing of title of x- and y-axis
Ferrous Applications II 42
M2O3(corundum) + Fe-liq
Fe-liq
Fe - Al - O - Ti
1600oC, mass O/(Fe+Al+O+Ti) = 5E-6
wt% Al
wt%
Ti
-5 -4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0
-3
-2.7
-2.4
-2.1
-1.8
-1.5
-1.2
-0.9
-0.6
-0.3
0
log wt% Al
log w
t% T
i
Inclusion diagram: Fe-Al-Ti-O, Al/Ti deoxidation
Fe-liq + M2O3(Corundum)
Fe-liq
Fe - Al - O
1600oC
log [wt% Al]
log
[w
t% O
]
-4 -3.5 -3 -2.5 -2 -1.5 -1 -.5 0
-4
-3.5
-3
-2.5
-2
-1.5
-1
Ferrous Applications II 43
M2O3(corundum) + Fe-liq
Fe-liq
Fe-liq
Pseudobrookite + Fe-liq
Pseudobrookite + Fe-liq
BIlmenite + Fe-liq
Fe - Al - O - Ti
1600oC, mass O/(Fe+Al+O+Ti) = 10E-6
log wt% Al
log w
t% T
i
-5 -4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0
-3
-2.7
-2.4
-2.1
-1.8
-1.5
-1.2
-0.9
-0.6
-0.3
0
Al2O3
Ilmenite (Ti2O3-rich phase)
Ti3O5
56[wt ppm O]
201512
10
50
30
20
1512
80
30
810 =4.5 ppm
50T = 1600
oC
Liquid
log [wt% Al]
log
[w
t% T
i]
-4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
M2O3(corundum) + Fe-liq
Fe-liq
Fe - Al - O - Ti
1600oC, mass O/(Fe+Al+O+Ti) = 5E-6
wt% Al
wt%
Ti
-5 -4.5 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0
-3
-2.7
-2.4
-2.1
-1.8
-1.5
-1.2
-0.9
-0.6
-0.3
0
log wt% Al
log w
t% T
i Inclusion diagram: Fe-Al-Ti-O, Al/Ti deoxidation
1) Change oxygen content and calculate similar diagram
2) Superimpose all the diagrams together
3) Calculate the phase boundaries from Equilib (or simply
connect boundaries in the calculated diagram)
Iso oxygen 5ppm line
Ferrous Applications II 44
Inclusions after Mn/Si deoxidation
Ferrous Applications II 45
Al-killed Ti-bearing steel
Ferrous Applications II 46
Al-killed Ti-bearing steel
Ferrous Applications II 47
Reoxidation of Al-killed Ti-bearing steel
“Recycle all streams”
• You don’t have to save the streams one by one. But the
results will be used only one time because it is not saved
under a special stream name.
• Convenient option when you want to do just one calculation
Ferrous Applications II 48
Reoxidation of Al-killed Ti-bearing steel
Addition of oxygen to simulate
reoxidation phenomena.
Actual source of oxygen could be
high-SiO2 slag or refractories
Ferrous Applications II 49
Reoxidation of Al-killed Ti-bearing steel
SLAGA#1
SLAGA#1
SLAGA#1
CORU#1
CORU#1
CORU#1
CORU#1
100% [Rc_Fe-liq] + 100% [Rc_M2O3(Corundum)] + <A> O2
C:\Slag-Steel-Inclusions\Equi0.res 25Sep12
Alpha
gra
m
0.00 0.01 0.02 0.03 0.04 0.05
0.00
0.05
0.10
0.15
0.20
+ 0.12253 gram ASlag-liq#1
(0.12253 gram, 1.1558E-03 mol)
(1600 C, 1 atm, a=1.0000)
( 33.379 wt.% Al2O3 FToxid
+ 0.17724 wt.% SiO2 FToxid
+ 0.83830 wt.% FeO FToxid
+ 1.1051E-03 wt.% Fe2O3 FToxid
+ 1.9943 wt.% MnO FToxid
+ 40.135 wt.% Ti2O3 FToxid
+ 23.475 wt.% TiO2 FToxid
+ 1.0928E-03 wt.% Mn2O3 FToxid)
This calculation shows that a mixed inclusion of Al2O3(s) and liquid (Al2O3-TiO2-Ti2O3)
can be formed by the reoxidation of Al-killed Ti-bearing steel.
Nozzle clogging.
Ferrous Applications II 50
TiN formation in Al-killed and Ti-bearing steel
Original steel composition at 1600C: high N and high Ti may form TiN
Ferrous Applications II 51
TiN formation in Al-killed and Ti-bearing steel
TiN(s)
CORU#1CORU#1CORU#1CORU#1
100% [Rc_Fe-liq] + 100% [Rc_M2O3(Corundum)]
C:\Slag-Steel-Inclusions\Equi0.res 25Sep12
T(C)
gra
m
1500 1510 1520 1530 1540 1550 1560 1570 1580 1590 1600
0.00
0.05
0.10
TiN(s) CORU#1CORU#1CORU#1CORU#1
BC
C
FeL
Q
100% [Rc_Fe-liq] + 100% [Rc_M2O3(Corundum)]
C:\Slag-Steel-Inclusions\Equi0.res 25Sep12
T(C)
gra
m
1500 1510 1520 1530 1540 1550 1560 1570 1580 1590 1600
0
10
20
30
40
50
60
70
80
90
100
Liquid steel
+ BCC Liquid steel
During the solidification,
a large amount of TiN can be formed.
Ferrous Applications II 52
Nozzle Clogging in Ti-bearing Al-killed steel
• Kawashima et al., CAMP-ISIJ (1991)
– Liquid Al-Ti-O (reoxidization) attached to Al2O3 inclusions
• Basu et al. ISIJ Int. (2004)
Significant difference in nozzle clogging of Ti-bearing steel from that of Ti-free
steel is the existence of Al-Ti-O inclusions covering Al2O3 core oxides.
Reoxidation in tundish (high-SiO2 slags) causes the nozzle clogging.
Ferrous Applications II 53
Inclusions generated by reoxidation process
RH process after Ti addition (POSCO)
Doo et al. (2007)
Al2O3
Ti-Al-O hole
Reoxidation in Tundish
(high SiO2 slags)
Park et al. (2004)
Reoxidation in Tundish
Basu et al. (2004)
Ti/Al of outer layer = 1.0~1.5
Ferrous Applications II 54
Inclusion causing nozzle clogging in Al-killed Ti-bearing steel
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.10.20.30.40.50.60.70.80.9
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
mole fraction
corundum
TiO2 + L
ilmenite + Ti3O5
Ti3O5 + L
co
run
du
m +
L
+ ilmenite + L
ilmenite + Llo
g P
O2 =
-11
-12
-13
-14
Al2O3
Ti2O3 TiO2
+ A
l2 T
iO5 +
LAl2TiO5 + L
Al2O3
Ti2O3 TiO2
Al2O3
Ti2O3 TiO2
Al2O3
Ti2O3 TiO2
Al2O3
Ti2O3 TiO2
Al2O3
Ti2O3 TiO2
Al2O3
Ti2O3 TiO2
T = 1600oC
-10
Liquid
Magneli + L
coru
ndum
-9.0
1) Drawing the phase diagram of the Al2O3-
Ti2O3-TiO2 system.
2) Drawing the same diagram with fixed PO2 and
superimposing them.
Ferrous Applications II 55
Calculated inclusion composition in Fe-Al-Ti-O liquid at 1600oC
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.10.20.30.40.50.60.70.80.9
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Al2O3
Ti2O3TiO2 + FeOmole fraction
Al2O3
Ti2O3
Al2O3
Ti2O3
Al2O3
Ti2O3
Al2O3
Ti2O3
Al2O3
Ti2O3
Al2O3
Ti2O3
Al2O3
Ti2O3
Al2O3
Ti2O3
Al2O3
Ti2O3
corundum
L
ilmenite + Ti3O5 + LTi3O5 + L
corundum + L+ ilmenite + L
ilmenite + LT
i = 1
0p
pm
50
100
500
1000
Similar to Mn/Si
deoxidation calculations
1) Drawing the phase diagram of the Al2O3-Ti2O3-TiO2
system.
2) Calculating equilibrium inclusion (Al2O3-T2O3-TiO2)
composition in liquid Fe containing small amounts of O
with certain fixed amounts of Ti. Then, plotting the
inclusion compositions on the phase diagram.
Ferrous Applications II 56
Newly calculated inclusion diagram of Fe-Al-Ti-O system
Al2O3
Ti2O3
Ti3O5
56[wt ppm O]
20
15
12
10
50
30
20
15
12
80
30
810 =4.5 ppm
50T = 1600
oC
Liquid
log [wt% Al]
log
[w
t% T
i]
-4.0 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0Existence of Liquid Al2O3-Ti2O3-TiO2
phase at 1600oC
Al deoxidation + Ti addition
Reoxidation
(Nozzle Clogging)
Ferrous Applications II 57
RH Vessel Refractory
Snorkel
RH Vessel
Ladle
O2 Lance
RH OB
• High amount of oxygen blowing
• Increase of ferro-alloy (Al, Si, Mn, etc) addition
→ More severe local corrosion of RH vessel refractory
Normal corrosion
Abnormally severe corrosion
Flow pattern in RH
CFD model
Ferrous Applications II 58
Quite enough thermodynamic database
(gas, molten steel, slag, refractory, etc…)
Write kinetic process using Macro :
input/output to Excel spread sheet
Reaction zone 1
Reaction zone 2
Reaction zone 3
Heat & Mass balance !!
…… Van Ende et al: ‘A Kinetic Model for the Ruhrstahl Heraeus (RH)
Degassing Process’, Metall. Mater. Trans. B, 2011, p. 477
Concept for RH process simulation modeling
Ferrous Applications II 59
RH Vessel Refractory
Predicted slag composition in RH
vessel from RH process simulation
M.-K. Cho, M.-A. Van Ende, T.-H. Eun and I.-H. Jung, “Investigation of slag-refractory interactions for the
Ruhrstahl Heraeus (RH) vacuum degassing process in steelmaking”, J. Eur. Ceram. Soc., 2012, 32,1503-1517.
Experimental and calculation conditions
F1,F2 C1,C2
Ferrous Applications II 60
Refractory finger tests at 1600oC
Ferrous Applications II 61
Thermodynamic Calculations: Refractories – Slag Interactions
Ferrous Applications II 62
Ladle glaze formation
Dipping time: 120 sec CaO SiO2 Al2O3 MgO
54.06 10.47 26.24 9.23
Slag composition (wt.%)
CaO SiO2 Al2O3 MgO
2.35 0.76 88.06 8.35
Refractory composition (wt.%)
As-received Dipped for 120 sec
Ferrous Applications II 63
Glazed Refractory
Glaze
Ferrous Applications II 64
Glaze (Reaction product of slag and refractory)
Slag
Spinel
CaAl12O19
CaAl4O7
Al2
O3
x slag + (1-x) refractory
ph
ase
dis
trib
uti
on
(w
t%)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0
10
20
30
40
50
60
70
80
90
100
Al2O3
CaO
SiO2
MgO
x slag + (1-x) refractory
sla
g c
om
po
siti
on
(w
t %
)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0
10
20
30
40
50
60
70
spinel islands
Glaze composition (glass)
CaO SiO2 Al2O3 MgO
35.8 6.6 51.1 6.5
Glaze area: glass + spinel
Original refractory Ladle slag
Ferrous Applications II 65
Equilibrium stability of 20MgO-78Al2O3-2CaO refractories
Equilibrium stability calculations with temperature: refractories
Ferrous Applications II 66
CaAl4O7(s)
CaAl4O7(s)
CaMg2Al16O27(s) CaMg2Al16O27(s) CaMg2Al16O27(s)
CaMg2Al16O27(s)
SPINA SPINA SPINA
SPINA
SLAGA#1SLAGA#1
2 CaO + <A> MgO + <98-A> Al2O3
c:\FactSage\casestudy\Equi0.res 22May09
T(C)
gra
m
1200 1300 1400 1500 1600 1700 1800
0
10
20
30
40
50
60
70
80
90
Equilibrium stability calculations with temperature: refractories
The refractory is mechanically unstable above 1600oC:
- considerable volume change due to the significant change in phase distribution
The refractory cannot be used above 1690oC:
- significant amount of liquid phase formation
Ferrous Applications II 67
Thermal Stability Test of Refractories
wt% REF-1 2 3 4 5 6
Al2O3 88 60 11 4 0.5 0.5
MgO 9 38 58 61 89 75
CaO 2 2 0.9 0.7
Cr2O3 20 29
Fe2O3 8.8 4.8
SiO2 1.6 0.4 0.5 1.2
C 7 17
Al 2 4
MgO
Spinel
SlagCa3MgAl4O10
(gram) 60 Al2O3 + 38 MgO + 2 CaO
Temperature (C)
ph
ase
dis
trib
uti
on
(w
t%)
1200 1300 1400 1500 1600 1700 1800 1900
0
10
20
30
40
50
60
70
80
90
Spinel
CaMg2Al16O27
Al2O3
Ca2Mg2Al28O46
CaAl12O19
(gram) 88 Al2O3 + 9 MgO + 2 CaO
Temperature (C)
ph
ase
dis
trib
uti
on
(w
t%)
1200 1300 1400 1500 1600 1700 1800 1900
0
10
20
30
40
50
60
70
80
90
REF-1 REF-2
Ferrous Applications II 68
Thermal Stability Test of Refractories
CaMgSiO4
Mg2SiO4
Slag
Spinel
MgO
(gram) 11 Al2O3 + 58 MgO + 0.9 CaO + 20 Cr2O3 + 8.8 Fe2O3 + 1.6 SiO2
Temperature (C)
ph
ase
dis
trib
uti
on
(w
t%)
1200 1300 1400 1500 1600 1700 1800 1900
0
10
20
30
40
50
60
70
80
90
Slag
Spinel
MgO
a-Ca2SiO4a'Ca2SiO4
(gram) 4 Al2O3 + 61 MgO + 0.7 CaO + 29 Cr2O3 + 4.8 Fe2O3 + 0.4 SiO2
Temperature (C)
ph
ase
dis
trib
uti
on
(w
t%)
1200 1300 1400 1500 1600 1700 1800 1900
0
10
20
30
40
50
60
70
80
90
C
MgO
Al4C3Spinel
(gram) 0.5 Al2O3 + 89 MgO + 0.5 SiO2 + 7 C + 2 Al
Temperature (C)
ph
ase
dis
trib
uti
on
(w
t%)
1200 1300 1400 1500 1600 1700 1800 1900
0
10
20
30
40
50
60
70
80
90
REF-5
REF-3 REF-4
Depending on the refractory compositions,
the refractory components can vary drastically.
Formation of liquid
Stability of refractory
Change in MgO/Spinel fraction
Mechanical wear resistance
Volume change
Ferrous Applications II 69
Refractory – Liquid Inclusion Interactions
Stopper Head
SEN Collar
Inner side/mouth
of SEN
Stopper (Al2O3-C)
Corroded area
Inner side of SEN
SEN (submerged entry nozzle)
melt
M.-K. Cho and I.-H. Jung, “Corrosion of nozzle refractories by liquid inclusion in high oxygen steels”,
ISIJ Inter. 2012, vol. 52, pp. 1289-1296.
Ferrous Applications II 70
Refractory – Liquid Inclusion Interactions P
lease s
ee t
he d
eta
ils in t
he I
SIJ
paper
Ferrous Applications II 71
Refractory – Liquid Inclusion Interactions
Please see the details in the ISIJ paper
Ferrous Applications II 72
Refractory – Liquid Inclusion Interactions P
lease s
ee t
he d
eta
ils in t
he I
SIJ
paper
Relative stability of the refractories against liquid MnO-SiO2 type inclusions
Ferrous Applications II 73
Refractory-Steel Interaction
Ferrous Applications II 74
Refractory-Steel Interaction
FeLQ FeLQ FeLQ FeLQ
SPINA#1
SPINA#1
SPINA#1
SPINA#1
MeO_A
MeO_A
MeO_A
CO
RU
#1
95 Fe + 4 Mn + Si + <100-100A> MgO +
C:\Slag-Steel-Inclusions\Equi0.res 24Sep12
Alpha
gra
m
0.0 0.2 0.4 0.6 0.8 1.0
0
20
40
60
80
100
Mn_FeLQ Mn_FeLQ Mn_FeLQ Mn_FeLQ
Si_FeLQ Si_FeLQ Si_FeLQ Si_FeLQ
Al_FeLQAl_FeLQ Al_FeLQ Al_FeLQMg_FeLQ Mg_FeLQ Mg_FeLQ Mg_FeLQO_FeLQ O_FeLQ O_FeLQ O_FeLQ
95 Fe + 4 Mn + Si + <100-100A> MgO +
C:\Slag-Steel-Inclusions\Equi0.res 24Sep12
Alpha
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Change in steel composition
Change in the amount of phases
<A> Al2O3 + <1-A> Al2O3
<A> Al2O3 + <1-A> Al2O3
Ferrous Applications II 75
85%Mn-15%Fe melt
Refractories
1g Mn-Fe melt + 1g refractory (MgO-Cr2O3)
Melt / refractory reactions simulation
Liquid
Spinel (MgCr2O4-MnCr2O4)
(MgO-MnO)
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Cr2O3
<A> MgO + <1-A> Cr2O3
gra
m
0.0 0.2 0.4 0.6 0.8 1.0
0
0.2
0.4
0.6
0.8
1
1.2
MgO
MnO
Cr2O3
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Cr2O3
<A>MgO + <1-A>Cr2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
Cr2O3 MgCr2O4 MgO
(Spinel)
(MgO-MnO)
MgCr2O4
MnCr2O4
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Cr2O3
<A> MgO + <1-A> Cr2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
Fe
MnCr
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Cr2O3
<A> MgO + <1-A> Cr2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
Steel
High Mn-Fe melt storage for TWIP steel production
Ferrous Applications II 76
LIQU
(MgO-MnO)
Corun
dum
(Al2
O3)
Spinel (MgAl2O
4-MnAl2O
4)
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Al2O3
<A> MgO + <1-A> Al2O3
gra
m
0.0 0.2 0.4 0.6 0.8 1.0
0
0.2
0.4
0.6
0.8
1
MgO
MnO
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Al2O3
<A> MgO + <1-A> Al2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
Fe
Mn
Al
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Al2O3
<A> MgO + <1-A> Al2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
MgAl2O4
MnAl2O4
Al8O12
0.15 Fe + 0.85 Mn + <A> MgO + <1-A> Al2O3
<A> MgO + <1-A> Al2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
Al2O3 MgAl2O4 MgO
MgO
Spinel Steel
1g Mn-Fe melt + 1g refractory (MgO-Al2O3)
High Mn-Fe melt storage for TWIP steel production
Ferrous Applications II 77
Fe
Mn
Al
<77.9B> Fe + <20B> Mn + <1.5B> Al + <0.6B> C +
<A> MgO + <1-A> Al2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
Liquid
MgO
Al2 O
3
MgAl2 O
4 -MnAl2 O
4
<77.9B> Fe + <20B> Mn + <1.5B> Al + <0.6B> C +
<A> MgO + <1-A> Al2O3g
ram
0.0 0.2 0.4 0.6 0.8 1.0
0
0.2
0.4
0.6
0.8
1
Twip steel
Refractories
Refractory for TWIP steel: Fe-20%Mn-1.5%Al-0.6%C
T = 1500oC
Steel
MgO-Al2O3 type: Very stable refractory
Ferrous Applications II 78
Twip steel
Refractories
Refractory for TWIP steel: Fe-20%Mn-1.5%Al-0.6%C
T = 1500oC
Steel
MgO-Cr2O3 type: less stable
Cr pickup
Al loss
Fe
Mn
Cr
<77.9B> Fe + <20B> Mn + <1.5B> Al + <0.6B> C +
<A> MgO + <1-A> Cr2O3
we
igh
t %
0.0 0.2 0.4 0.6 0.8 1.0
0
10
20
30
40
50
60
70
80
90
100
Steel
MgC
r2 O
4 -MnC
r2 O
4M
gO-M
nO-s
mall C
r 2O 3
MgAl2O4-MnAl2O4
Cr
2 O3 -A
l2 O3
<77.9B> Fe + <20B> Mn + <1.5B> Al + <0.6B> C +
<A> MgO + <1-A> Cr2O3
gra
m
0.0 0.2 0.4 0.6 0.8 1.0
0
0.2
0.4
0.6
0.8
1
Ferrous Applications II 79
Desulphurization
Desulphurization of hot metal in the De-S station,
Desulphurization of steel during ladle treatment
and calculating sulphide capacity
More examples can be found in:
http://in-ho-group.mcgill.ca/publicfiles.php#
Ferrous Applications II 80
Desulphurization of Hot Metal
• The hot metal tapped out of the blast furnace typically contains 0.04-0.07% S.
• To reduce the amount of sulphur in the hot metal between the blast furnace
and the oxygen converter, desulphurization is usually performed at a De-S
station such as KR using flux (CaO, CaC2, Mg, …)
• In secondary steelmaking (recently in LF unit), de-S can occur between slag
(CaO-rich) and steel due to strong agitation.
Blast Furnace (BF) Basic Oxygen Furnace
(BOF)
0.04-0.07% S
~ 0.01% S
Torpedo Car
KR ~ 0.001% S
Ladle Furnace
(LF)
Ferrous Applications II 81
Desulphurization of Hot Metal
The following reactions have been proposed to reduce the sulphur content in hot
metal:
In the following pages, it will be shown how FactSage could be used to calculate
the efficiency of each desulphurizing agent.
It will then be shown how the exact amount of desulphurizing agent can be
selected to achieve the desired sulphur content.
Ferrous Applications II 82
Desulphurization of Hot Metal using Mg
1. Double-click on units…
2. … to select the
desired units
3. Enter the hot metal composition
and put <A> for the
desulphurizing agent amount
4. Click on “Data Search”…
6. Click “Next”
5. … and select the FTmisc database
This example can be found
in EquiCase2-1.dat
Ferrous Applications II 83
Desulphurization of Hot Metal using Mg
3. We need to select each phase only once, so we will have
to “suppress duplicates”
1. Right-click on “pure solids”
2. The selection
contains data from both
FTmisc and FactPS.
Some of the data are
overlapping (highlighted
in red as “Duplicates”)
Ferrous Applications II 84
Desulphurization of Hot Metal using Mg
1. Left-click on “suppress duplicates”
4. Press “apply” – Now the number of solids selected should be inferior to
that selected in the beginning.
3. Press “OK”
2. Then enter the
database names in the
order they should be
prioritized.
Here, FTmisc was given
priority over FactPS
Ferrous Applications II 85
Desulphurization of Hot Metal using Mg
1. Left-click to select the liquid steel solution phase
3. Enter the desired
equilibrium
temperature.
2. If you don’t see the available
solution phase, click “show all”
4. We will vary the
amount of
desulphurizing
agent from 0 to 1 g
in steps of 0.01g
5. Press “Calculate”
Ferrous Applications II 86
Desulphurization of Hot Metal using Mg
Now we want to see how the amount of sulphur in the hot metal decreases with the
addition of magnesium.
1. Press “Output”
→ “Plot” → “Plot
Results…”
2. Press “Axes”
3. This window will
pop-up
Ferrous Applications II 87
Desulphurization of Hot Metal using Mg
1. Press “Y-variable”
2. Select “weight %” in
“log10(Y)” scale
4. In the same way,
select alpha as the X-
variable
3. Select the maximum, minimum
and incremental value for the graph
Ferrous Applications II 88
Desulphurization of Hot Metal using Mg
Now we can see that the axes have
been selected. We just need to
choose sulphur as the species.
3. Press “OK” 2. Select S(FeLQ) – sulphur in
the liquid steel solution.
1. Press “Select” species
Ferrous Applications II 89
Desulphurization of Hot Metal using Mg
1. Now we can see
that both the axes
and the species have
been selected.
2. The “Plot” button is
now activated. Click it!
Ferrous Applications II 90
Desulphurization of Hot Metal using Mg
1. It can be seen
that after the
addition of 0.1g
Mg, the
desulphurization is
not so effective.
2. If our target was
0.001% S, we can
read off the graph
that this sulphur
level will be
achieved after
adding
approximately
0.05g Mg.
3. However, there
is a better way.
Ferrous Applications II 91
Desulphurization of Hot Metal using Mg: Composition target
1. Right-click on the
Ftmisc-FeLQ selection 3. This
window will
pop-up
2. Click on
“composition
target”
Ferrous Applications II 92
Desulphurization of Hot Metal using Mg: Composition target
1. Select “element
composition”
3. Enter the desired
value (here –
0.001%)
2. Choose
element S
4. Press “OK”
Ferrous Applications II 93
Desulphurization of Hot Metal using Mg: Composition target
1. Now “C” indicates that we have selected a
composition target for this calculation
3. Press “Calculate”.
Note that only one
calculation will be
performed. 2. We must leave
the <A> field blank,
because <A> is
what we want to
calculate.
Ferrous Applications II 94
Desulphurization of Hot Metal using Mg: Composition target
1. The <A> value for reducing sulphur content to 0.001% is 0.0494g.
2. The mass fraction of S is
exactly what we want it to be.
Ferrous Applications II 95
Desulphurization of Hot Metal using CaC2
In the same manner, we can calculate the desulphurization ability of CaC2
We will keep the same hot metal
composition, the only thing we will
change is the desulphurizing agent This example can be found
in EquiCase2-2.dat
Ferrous Applications II 96
Desulphurization of Hot Metal using CaC2
The same conditions are selected
Ferrous Applications II 97
Desulphurization of Hot Metal using CaC2
After addition of
0.14g of CaC2, the
amount of S in the
hot metal becomes
so small that the
reaction does not
proceed and CaC2 is
precipitated as a
solid phase.
Ferrous Applications II 98
Desulphurization of Hot Metal using CaC2
This can also be
seen on the graph –
after <A>=0.14, the
sulphur level
remains constant.
1. In order to
compare this graph
with the graph for
Mg
desulphurization,
we should save this
figure.
2. But first, to differentiate this curve
from the others, we will change the
labels.
Ferrous Applications II 99
Desulphurization of Hot Metal
It can now readily
be seen that Mg
and CaO+Mg are
the most effective
hot metal
desulphurizing
agents.
Ferrous Applications II 100
Desulphurization of Hot Metal
It is also convenient to compare the amounts obtained using “Composition Target”
Ferrous Applications II 101
Desulphurization of Steel using Slag
We will now apply the same calculations for the desulphurization of steel in the
ladle.
The starting steel contains 0.01% S and it needs to be reduced down to 0.001% S
We will also assume that a slag is present in the ladle. It consists of 40% CaO,
40% Al2O3, 10% MgO and 10% SiO2. The ratio of slag to metal is 1/10
Ferrous Applications II 102
Desulphurization of Steel using Slag
1. Enter the metal and slag composition
2. In “Data Search” select
FTmisc and FToxid
This example can be found
in EquiCase2-7.dat
Ferrous Applications II 103
Desulphurization of Steel using Slag
1. Enter the <A>
and temperature
2. Select liquid steel and
SlagA as the solutions
3. Note that the slag phase
is selected with possible
immiscibility
4. Press “Calculate”
Ferrous Applications II 104
Desulphurization of Steel using Slag
Results show a
slag phase and a
metal phase
Solid periclase
(MgO) appears as
<A> is increased
We can plot the
results in the same
way as was done
for the hot metal
desulphurization in
the previous slides
Ferrous Applications II 105
Desulphurization of Steel using Slag
A constant
decrease in metal
sulphur content is
observed
Ferrous Applications II 106
Desulphurization of Steel using Slag
Another useful way to visualize these results, is the sulphur partition coefficient:
Ls=(Sin slag)/[Sin metal]
1. Press “Output” →
“Save or Print” → “Save
or Print As …”
2. Select “Open Text
Spreadsheet”
3. Press “Spreadsheet
Setup”
Ferrous Applications II 107
Desulphurization of Steel using Slag
1. Select “Alpha” as the
property column
2. Select “wt%” as the
Species properties
3. Select the desired species
Ferrous Applications II 108
Desulphurization of Steel using Slag
1. Select sulphur from
liquid steel and all
elements from the slag
2. Press “OK”
Ferrous Applications II 109
Desulphurization of Steel using Slag
1. Press “OK” on
this window and
the next one
Ferrous Applications II 110
Desulphurization of Steel using Slag
2. It is convenient to copy the
whole table and paste it into Excel.
1. A spreadsheet with the
composition of slag and metal at
each <Alpha> value will appear.
Ferrous Applications II 111
Desulphurization of Steel using Slag
2. The last column was
used to calculate the
sulphur partition
coefficient Ls.
1. All unnecessary columns
were deleted keeping only
the sulphur content in the
steel and the slag.
3. Plotting Alpha against log(Ls)
Ferrous Applications II 112
Calculating Slag Sulphide Capacity
A good way of comparing the ability of a slag to absorb sulphur is the sulphide
capacity calculated in the following manner:
CS=(Sin slag)*(PO2/PS2)1/2
In the following
slides, the
sulphide
capacity of four
different slags
will be calculated
Ferrous Applications II 113
Calculating Slag Sulphide Capacity
1. Enter the amount and species for
the first slag
2. Select FactPS and FToxid
databases
Ferrous Applications II 114
Calculating Slag Sulphide Capacity
1. Select gas and SlagA as possible products
2. We will calculate
the sulphide
capacity at three
temperatures: 1580,
1600 and 1620°C 3. Press “Calculate”
Ferrous Applications II 115
Calculating Slag Sulphide Capacity
It is now possible to calculate the sulphide capacity
using these results.
In the next slides,
two ways of
calculating sulphide
capacity will be
demonstrated.
Ferrous Applications II 116
Calculating Slag Sulphide Capacity
The first way is to use Excel 1. Save the results
in a spreadsheet
2. Press
“Spreadsheet setup”
Ferrous Applications II 117
Calculating Slag Sulphide Capacity
1. Set T(C) as the
system property
3. Select the species
2. We need wt%S and the activity of
O2 and S2 in the gas, so select “wt%”
and “a” as the species properties.
Ferrous Applications II 118
Calculating Slag Sulphide Capacity
1. Select O2(g),
S2(g) and all
Elements in SlagA
2. Press “OK” on all
three screens
Ferrous Applications II 119
Calculating Slag Sulphide Capacity
1. All the needed results (and even more) appear in the spreadsheet.
3. Calculate the sulphide capacity in a separate column.
2. Copy the results in Excel and delete the unnecessary columns
4. Plot log(Cs) versus temperature
Ferrous Applications II 120
Calculating Slag Sulphide Capacity
Another way to plot the sulphide capacity is to use
the function builder tool coupled with Fact-XML
1. Press “Edit/Create
functions” under the Fact-
Function-Builder Menu
Ferrous Applications II 121
Calculating Slag Sulphide Capacity
1. We need to select wt%S as one
variable
2. Select “Amount/Composition”
under “Variable selection”
3. Select “wt%”
4. Right-click on S(total) in slag
and add it to variables list
Ferrous Applications II 122
Calculating Slag Sulphide Capacity
1. The amount of S now appears
in the variables list.
2. Right-click on the variable and
rename it “wtS”
3. Partial pressure and activity of a
gas is the same thing, so we need
to select activity of O2 and S2 in
the gas as the two other variables.
Ferrous Applications II 123
Calculating Slag Sulphide Capacity
1. Select “Activity” under “Variable
Selection”
2. Right-click on O2 and S2 and
add them to the variable list
3. Rename the
variables to
aO2 and aS2
accordingly
Ferrous Applications II 124
Calculating Slag Sulphide Capacity
1. Enter the function for log(Cs)
2. Press “preview results”
3. Note that the
results are the
same as for the
Excel
calculation
Ferrous Applications II 125
Calculating Slag Sulphide Capacity
1. Save the function as
“Sulphide_Capacity”
2. Close the window
Ferrous Applications II 126
Calculating Slag Sulphide Capacity
1. Go back to the “Results”
window, and select the
“Sulphide_Capacity” function
group
3. Click “Refresh Results …”
2. Check “Always
calculate function
groups”
Ferrous Applications II 127
Calculating Slag Sulphide Capacity
1. A separate
“Functions” tab will
appear with the
results of the
calculations
2. Each tab will
have information
on the function
along with the
calculated
equilibrium.
Ferrous Applications II 128
Calculating Slag Sulphide Capacity
1. In order to plot the sulphide capacity as a function of
temperature, press the XML button
2. Then select
“Graph” → “Setup”
3. Import the
“Sulphide_Capacity” function
Ferrous Applications II 129
Calculating Slag Sulphide Capacity
1. Select “Functions” as the Y-Axis 2. Select “Temperature” as the X-axis
3. Adjust the min and max
values, the step, etc.
4. Press “Draw”
Ferrous Applications II 130
Calculating Slag Sulphide Capacity
The figure is then
obtained
Ferrous Applications II 131
Calculating Slag Sulphide Capacity
Repeating the same procedure for the other slag compositions, it is
possible to compare the sulphide capacities of the different slags.
Ferrous Applications II 132
Slag cooling and heating
(Enthalpy diagram)
• When slag forms from pure oxides, a certain amount of heat
(enthalpy) is needed.
• When slag is cooled down, a certain amount of heat should be
extracted.
• FactSage Phase diagram: Enthalpy diagram
Ferrous Applications II 133
Heat required to form and increase temperature of slag
Pure FeO(s) is not in the FToxid compound database
(Strictly speaking, FeO is a non-stoichiometric
compound so it is in the FToxid MeO solution)
Initial condition
FactSage can use two variables, <A> and <B>
<A> can actually be varied but <B> should be constant
H = Hfinal – Hinitial
So initial conditions(phase,T,P) should be defined
Ferrous Applications II 134
Final condition
H = Hfinal – Hinitial
This is the heat we add to increase the
temperature up to 1600oC.
That is, H = Hslag at 1600C – Hinitial oxides at 25C
This is the enthalpy of the final
products at 1600oC
Heat required to form slag and increase the temperature of slag
Ferrous Applications II 135
Heat required to form slag and increase the temperature of slag
<A> MgO + <1-A-B> FeO + <B> SiO2
Alpha
De
lta
H(J
)
0.0 0.1 0.2 0.3 0.4 0.5
1475
1525
1575
1625
1675
1725
1775
1825
1875
1925
Fe(s) Fe(s) Fe(s) Fe(s)
SLAGA#1 SLAGA#1
SLAGA#1
SLAGA#1
MeO_A
OlivA
OlivA
<A> MgO + <1-A-B> FeO + <B> SiO2
C:\Slag-Steel-Inclusions\Equi0.res 23Sep12
Alpha
gra
m
0.0 0.1 0.2 0.3 0.4 0.5
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
slag
Sla
g+
Oliv
ine
Sla
g+
Oliv
ine+
MeO
Oliv
ine+
MeO
Ferrous Applications II 136
Enthalpy diagram: phase change with H
Ferrous Applications II 137
• Only X-Y type diagram allowed.
• Y axis should be Enthalpy (H-HTmin).
• Hinitial (HTmin) is the enthalpy of products stable at Tmin. For example, Fe2SiO4
(fayalite_olivine) and SiO2 are stable at 0% MgO and 30% SiO2 rather than FeO
and SiO2.
30%SiO2
Tinitial
Iso-Temperature
Enthalpy diagram option
Enthalpy diagram: phase change with H
Ferrous Applications II 138
Enthalpy diagram: phase change with H
If we increase the temperature of the mixture of (monoxide + olivine) at 20 wt % MgO and 30 wt % SiO2
from 25 oC to 1625 oC, liquid slag is formed and the amount of heat required for this is about 2250 J/g.
125 oC
225 oC
325 oC
425 oC
525 oC
625 oC
725 oC
825 oC
925 oC
1025 oC
1125 oC
1225 oC
1325 oC
1425 oC
1525 oC
1625 oC
1725 oC
1825 oC
2025 oC2125
oC2225
oC2325
oC2425
oC
AMonoxide + AMonoxide#2 + AOlivine
AMonoxide + AOlivine
ASlag-liq + AMonoxide + AOlivine
ASlag-liq + AOlivine
ASlag-liq
ASlag-liq + AMonoxide
AOlivine + SiO2(s)
AOlivine + SiO2(s2)
AOlivine + SiO2(s4)
MgO - FeO - SiO2
SiO2/(MgO+FeO+SiO
2) (g/g) = 0.3, 1 atm
MgO/(MgO+FeO+SiO2) (g/g)
H -
H25 C
(J/g
)
0 0.1 0.2 0.3 0.4 0.5 0.6
0
500
1000
1500
2000
2500
3000
If w
e h
ea
t t
he
mix
ture
of (m
on
oxid
e +
oliv
ine
) a
t 3
0 w
t %
Mg
O a
nd
30
wt
% S
iO2
fro
m 2
5 o
C b
y a
dd
ing
15
00
J/g
,
the
mix
ture
be
co
me
s a
mix
ture
of (liq
uid
sla
g +
oliv
ine
) a
t
ab
ou
t 1
42
5 o
C.
Ferrous Applications II 139
Enthalpy diagram: phase change with H
125 oC
225 oC
325 oC
425 oC
525 oC
625 oC
725 oC
825 oC
925 oC
1025 oC
1125 oC
1225 oC
1325 oC
1425 oC
1525 oC
1625 oC
1725 oC
1825 oC
1925 oC2025
oC2125
oC2225
oC2325
oC
Orthopyroxene + AOlivine
AMonoxide + AOlivine
ASlag-liq + AOlivine
ASlag-liq
ASlag-liq + AOlivine + SiO2(s4)
ASlag-liq + AClinopyroxene + AOlivine
AOlivine + SiO2(s4)
ASlag-liq + AMonoxide + AOlivine
MgO - FeO - SiO2
SiO2/(MgO+FeO+SiO
2) (g/g) = 0.4, 1 atm
MgO/(MgO+FeO+SiO2) (g/g)
H -
H25 C
(J
/g)
0 0.1 0.2 0.3 0.4 0.5
0
500
1000
1500
2000
2500
3000
Ferrous Applications II 140
Application: Addition of new compounds and
solutions (user defined) in calculations
MnCr2O4-MnAl2O4 ideal solid solution
• New stainless steel production: high
Mn stainless steel 400 grade. High
MnO formation in AOD / VOD refining
process
• MnCr2O4-MnAl2O4 inclusion
formation in Mn- and Cr-containing
steels
Ferrous Applications II 141
User Compound Database
(2) Select “mixer”
(1) Type the compounds
(3): add the MnO and Cr2O3 from known database
(4): select your own database (INHOBASE) and copy the result
Creating user compound database: MnCr2O4 from MnO and Cr2O3
Ferrous Applications II 142
User Compound Database
Go(cubic-MnCr2O4) = Go(MnO) + Go(Cr2O3) + Hf − TSf
Hf = -51 kJ/mol, S = 0 J/mol-K
Before Hf and Sf
after Hf and Sf
Ferrous Applications II 143
User Compound Database
Add H298, S298 and Cp
Creating user compound database:
MgCr2O4 from H298, S298 and Cp
Ferrous Applications II 144
Ideal solution between compounds
Database selection
Priority of database
Ferrous Applications II 145
Ideal solution between compounds
MnCr2O4-MgCr2O4 ideal sol’n: (Mg,Mn)Cr2O4
Both MnCr2O4 and MgCr2O4 are selected as ideal
solution #1 with no activity coefficients entered (ideal)
Ferrous Applications II 146
Ideal solution between compounds
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.10.20.30.40.50.60.70.80.9
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
SiO2
CaO Cr2O3mass fractions /(CaO+SiO2+Cr2O3)
Liqiud
Liquid + Ideal #1
O2 - CaO - SiO2 - Cr2O3 - MnO - MgO1700
oC, p(O
2) = 10
-11 atm, MnO/Z (g/g) = 0.1,
MgO/Z (g/g) = 0.05, Z=(CaO+SiO2+Cr
2O
3)
Ideal solution of
MgCr2O4-MnCr2O4
Liquid
Ferrous Applications II 147
Application: Addition of a new component in slag
V2O3 into molten slag for V distribution calculations
(Henrian solution)
Ferrous Applications II 148
New component in slag: Henrian activity coefficient
V2O3 containing slag // Liquid Fe-Al steel
All V goes to liquid Fe ??
(because no V oxide in slag yet)
Ferrous Applications II 149
New component in slag: Henrian activity coefficient
Setting activity coefficient
of V2O3 in slag
Ferrous Applications II 150
New component in slag: Henrian activity coefficient
Ferrous Applications II 151
New component in slag: Henrian activity coefficient
V in FeLq = 0.577 wt%
V2O3 in slag = 0.134 wt%
The distribution of V between slag and metal can
be varied depending on the activity coefficient.
(evaluated from experimental data)
Ferrous Applications II 152
Vanadium partition coefficient in
Steel/Slag melts based on literature data
(BOF condition)
FINAL REPORT for MIME572
• By Jonathan Spring
• Undergraduate student
McGill University
V distribution between steel and slag
More details can be found in:
http://in-ho-group.mcgill.ca/publicfiles.php#
Ferrous Applications II 153
Background • Partition coefficients used to quantify solute concentrations in
steel/slag
• Partition coefficient, Lv, = (wt% V) / [wt% V]
• No known expression to predict vanadium distribution coefficient
Henry’s Law • We are dealing with dilute solutions
• (V2O3) ~ 3 wt%
• 2 V + 3 O = V2O3
• Keq = AV2O3 / (AV2*AO
3)
• Activity = ϒV2O3xV2O3
• log10(ϒV2O3) = A/T + B
V distribution coefficient between steel and slag
Ferrous Applications II 154
Literature Search
• Found ~ 20 articles with data on vanadium partition coefficients in
slag/steel melts
• 3 of those contained tables of raw data with slag compositions (Zhang,
Shin and Inoue) and 2 were performed at similar temperatures (Shin and
Inoue). These 2 were used initially.
• Shin’s article dealt with slag containing Al2O3. His experiments were
performed without proper control of the oxygen partial pressure and the
partition coefficients for V he found were drastically different than in Inoue’s
article. His results are therefore unreliable. Furthermore, the initial V
partition coefficient model had trouble fitting Shin’s data. It was decided
after my presentation to redo the model using only Inoue’s data.
• Total data points: 63
V distribution coefficient between steel and slag
Ferrous Applications II 155
• 1550 °C: 15 data points
• 1600 °C: 28 data points
• 1650 °C: 18 data points
• Slag
– x SiO2
– x CaO
– x FeO
– x Fe2O3
– x MgO
• Lv for each data point
V distribution coefficient between steel and slag
Ferrous Applications II 156
Data from Inoue’s Article Slag (wt%)
T (C) (CaO) (SiO2) (FeO) (Fe2O3) (MgO) (V) Lv
1650 27 28 21 2 19 1 410.1
1650 19 22 36 4 16 1 751.4
1650 29 15 36 6 10 1 1087.6
1650 8 13 52 4 22 1 850.6
1650 25 7 47 11 8 2 1510.0
1650 17 3 58 12 7 2 1439.3
1650 1 4 71 6 16 1 1142.9
1650 1 15 50 3 29 1 705.9
1650 19 28 29 2 20 1 522.1
1650 28 22 30 4 13 1 761.7
1650 37 14 31 8 8 2 1174.2
1650 21 13 46 6 11 2 937.9
1650 31 7 40 13 7 2 1495.1
1650 0 1 82 6 8 2 1006.2
1650 1 7 71 5 14 1 900.7
The amount of V in the slag was not considered. The same fixed amount of V was
used for all equilibrium calculations and the subsequent calculation of Lv.
Ref: R. Inoue and H. Suito, Trans. ISIJ, vol. 22, p 705 (1982).
V distribution coefficient between steel and slag
Ferrous Applications II 157
• Databases: FToxid, Ftmisc (FeLQ), FactPS
• Equilibrium
– x SiO2
– x CaO
– x FeO
– x Fe2O3
– x MgO
– 300 g Fe
– 2 g V
100 g
3:1 metal to slag ratio
V distribution coefficient between steel and slag
Ferrous Applications II 158
• Assume V in slag exists as V2O3
Solid V2O3 was considered because solid V2O3 is stable at these temperatures.
V distribution coefficient between steel and slag
Ferrous Applications II 159
• Change “A” value, “B” assumed to be 0
V distribution coefficient between steel and slag
Ferrous Applications II 160
[Wt% V]
Lv = (Wt% V) = 68.6
•Calculate equilibrium
•Calculate Lv
•Compare to measured Lv
•Go back and try new <A>
value
•Trial and error
•More negative <A> value
creates a smaller Lv
Slag (wt%)
T (C) (CaO) (SiO2) (Fe2O3) (MgO) (FeO) Lv
1650 37 15 18 22 4 12.6
Ferrous Applications II 161
<A> Value to Activity Coefficient
log10(ϒV2O3) = A/T + B
log10(ϒV2O3) = -1025/1923
ϒV2O3 = 10^(-1025/1923)
ϒV2O3 = 0.293
Slag (wt%)
T (C) (CaO) (SiO2) (FeO) (Fe2O3) (MgO) (V) Lv A ϒ
1650 27 28 21 2 19 1 410.1 -1025 0.29
1650 19 22 36 4 16 1 751.4 -1200 0.24
1650 29 15 36 6 10 1 1087.6 -2175 0.07
1650 8 13 52 4 22 1 850.6 -1100 0.27
1650 25 7 47 11 8 2 1510.0 -2750 0.04
1650 17 3 58 12 7 2 1439.3 -2300 0.06
1650 1 4 71 6 16 1 1142.9 -1300 0.21
1650 1 15 50 3 29 1 705.9 -750 0.41
1650 19 28 29 2 20 1 522.1 -1000 0.30
1650 28 22 30 4 13 1 761.7 -1475 0.17
A more negative <A> value indicates a smaller activity coefficient.
V distribution coefficient between steel and slag
Ferrous Applications II 162
• The regression using slag basicity, A = aCaO/SiO2 + bMgO/SiO2 + c(FeO + Fe2O3), was discarded because the fit was not as good as for the regression using each slag component.
• The regression using each slag component was poor nonetheless. Another regression, using all slag components and the slag temperature, was introduced.
• Option #1 A = aCaO + bSiO2 + c(FeO + Fe2O3) + dMgO
• Option #2 (Option #1 including temperature) A = aT(K) + bCaO + cSiO2 + d(FeO + Fe2O3) + eMgO
• Option #3 (Option #2 including Constant) A = aT(K) + bCaO + cSiO2 + d(FeO + Fe2O3) + eMgO +
Constant
V distribution coefficient between steel and slag
Ferrous Applications II 163
• Regression #3 is best
– Slope of measured vs predicted <A> and
measured vs predicted Lv is closest to 1
– Smaller residuals
– Residuals are randomly distributed
• A = - 7 * Temperature (K) - 51 * wt% CaO +
133 * wt% SiO2 + 31 * (wt% FeO + wt% Fe2O3)
- 37 * wt% MgO + 10,100
• Need to test against more data!
V distribution coefficient between steel and slag
Ferrous Applications II 164
Zn Galvanizing process
Reduction furnace: selective oxidation
Galva-annealing: Zn melting and oxidation
Ferrous Applications II 165
Oxygen partial pressure control using dew-point control
N2-5%H2
Ice(H2O(s)), T= -30°C
PO2=?
Oxidation ?
H2 + 1/2O2 = H2O
Annealing T= 800°C
Hot Dip galvanizing
Cold worked at 300 °C
Dew point
Ferrous Applications II 166
We should select real gas to obtain
accurate Gibbs energy and volume
fraction of gas at low temperature
and high pressure.
N2-H2 gas with -30oC dew point
Ferrous Applications II 167
We will heat this gas at 800°C using
a stream file.
N2-H2 gas with -30oC dew point
Ferrous Applications II 168
Creating stream file
N2-H2 gas with -30oC dew point
Ferrous Applications II 169
Final partial pressure of oxygen
N2-H2 gas with -30oC dew point 800oC
Ferrous Applications II 170
Dew Point = 0
o C
-10o C -20
o C-30
0 C-40
o C-50
0 C
TemperatureoC
log
PO
2, b
ar
500 600 700 800 900 1000 1100 1200
-35-34
-33
-32
-31
-30
-29
-28
-27
-26
-25
-24
-23
-22
-21
-20
-19
-18
-17
-16
-15
Dew points – PO2/T Relationship
95%N2,5%H2
Dew Point 0o C
-100 C
-20o C
-30o C
-40o C
-500 C
Temperature0C
log p
O2,b
ar
500 600 700 800 900 1000 1100 1200
-35-34
-33
-32
-31
-30
-29
-28
-27
-26
-25
-24
-23
-22
-21
-20
-19
-18
-17
-16
-1590%N2,10%H2
Ferrous Applications II 171
Phase diagram PO2 – T: Oxidation of Fe-1%Mn-1%Si
Ferrous Applications II 172
BCC_A2
BCC_A2 + FCC(c,n)
FCC(c,n)
Rhodonite + BCC_A2 + SiO2(s2)
Rhodonite + BCC_A2 + SiO2(s)
Rhodonite + BCC_A2 + SiO2(s4)
Rhodonite + FCC(c,n) + SiO2(s4)
AOlivine + BCC_A2
AOlivine + BSpinel
Rhodonite + BCC_A2
Rhodonite + BCC_A2
O2 - Fe - Mn - Si
mass Mn/(Fe+Mn+Si) = 0.01, mass Si/(Fe+Mn+Si) = 0.01
T(C)
log
10(p
(O2))
(atm
)
500 600 700 800 900 1000
-40
-36
-32
-28
-24
-20
Ferrous Applications II 173
FCC + BCC
FC
C +
BC
C +
SiO
2
FCC + BCC + SiO2 + MnSiO3
FCC + BCC + MnSiO 3
FCC + BCC + Mn2SiO4
FCC + BCC + MnSiO3 + Mn2SiO4
Fe - C - Mn - Si - O2
800oC, p(O
2) = 10
-27.5 bar, C = 0.1%
wt% Mn
wt%
Si
0.0 0.5 1.0 1.5 2.0
0.0
0.5
1.0
1.5
2.0
Drawing of the diagram:
1) Collect all blue/red/green lines at different PO2 and superimpose them in one diagram.
2) The boundary of each colored line (different phase) is the phase boundary of the primary
oxide phases in the diagram.
EX17-3. Primary oxide formation diagram
Ferrous Applications II 174
Fe-Mn-Si at PO2=10-28atm, T=800°C
Ferrous Applications II 175
Boundaries for oxide phases
Ferrous Applications II 177
<BCC + SiO2>
<BCC
+ MnSiO3>
wt %Mn
wt
%S
i
0.0 0.5 1.0 1.5 2.0 2.5 3.00.0
0.5
1.0
1.5
2.0
2.5
3.0
<BCC +FCC
+ MnSiO3>
<BCC +FCC
+ Mn2SiO4>
(A)(B)
(C)
Mn = 0.5
Si = 1.5
Primary oxidation Secondary oxidation
Mn = 0.5
Si = 1.0
SiO2 formation
Si depletion
in metal
SiO2+MnSiO3 formationSiO2
MnSiO3
<BCC + SiO2>
<BCC
+ MnSiO3>
wt %Mn
wt
%S
i
0.0 0.5 1.0 1.5 2.0 2.5 3.00.0
0.5
1.0
1.5
2.0
2.5
3.0
<BCC +FCC
+ MnSiO3>
<BCC +FCC
+ Mn2SiO4>
(A)(B)
(C)
Mn = 0.5
Si = 1.5
Primary oxidation Secondary oxidation
Mn = 0.5
Si = 1.5
SiO2 formation
Si depletion
in metal
SiO2+MnSiO3 formationSiO2
MnSiO3
Primary and Secondary Oxidation
Ferrous Applications II 178
Oxidation phase diagram of Fe-0.002%C-Mn-Si steel at 800oC
Oxidation phase diagram
Ferrous Applications II 179
Remelting and oxidation of Zn galvanized steel
Zn
Fe-1%Mn-0.5%Cr
Air
2. Oxidation reaction
Zn (liquid)
Fe-1%Mn-0.5%Cr
Air
1. L/S Interfacial reaction
Reheating
(900 oC)
air
Original metal
Oxid
e layer
Oxidation Calculation
Log P(O2)
By controlling the partial pressure,
different layer oxides can be
calculated. But the partial pressure
does not decrease linearly with depth
of oxide layer. So this type of
calculation shows quantitative
oxidation behavior
Ferrous Applications II 180
FTlite database contains
reasonable Zn bath data for Zn-
galvanizing. So, this is chosen
instead of FSStel.
Interface reaction between liquid Zn and steel
Ferrous Applications II 181
Original steel:
Fe-1%Mn-0.5%Cr
Reaction products:
Zn-rich Liquid
Reaction products:
BCC + FCC
We need this liquid Zn for the
oxidation reaction
Save it as a stream
Interface reaction between liquid Zn and steel
Ferrous Applications II 182
Oxidation of liquid Zn
(1)
(2)
(2)-a
(1)-a
(1)-b
(1) Setting oxygen partial pressure:
activity or log activity can be fixed
(2) Remove duplicate compounds
Give a priority in database
Typically “FToxid > any metallic database > FactPS”
Ferrous Applications II 183
Oxidation of liquid Zn
Setting X-asix
Ferrous Applications II 184
Oxidation of liquid Zn
Liqu#1
BCC#1
SPINASPINA
SPINA
MeO_A MeO_A
ZNITAZNITA
ZNITA
TSpi
100% [Zn-liquid] + 0 O2
C:\FactSage\Equi0.res 1Oct12
log10(activity) O2(g)
gra
m
-30.0 -20.0 -10.0 0.0
0
10
20
30
40
50
BCC#1
SPINA
SPINA
MeO_A MeO_ATSpi
100% [Zn-liquid] + 0 O2
C:\FactSage\Equi0.res 1Oct12
log10(activity) O2(g)
gra
m
-30.0 -20.0 -10.0 0.0
0
01
02
03
04
05
air
Spinel + liquid Spinel +Monoxide + liquid
Zincite + BCC
Original metal
Oxid
e layer
Zincite + Spinel
It is hard to predict the thickness of each layer
ZnCr2O4
MnO-rich monoxide
ZnO-rich Zincite
Ferrous Applications II 185
Carburization and Decarburization of Steel
CO / CO2 is variable
Ferrous Applications II 186
Carburization and Decarburization of Steel
Ferrous Applications II 187
An amount of carbon in FCC phase (Fe)
wei
gh
t %
<Alpha>
Carburization and Decarburization of Steel
Ferrous Applications II 188
Composition Target:
“ How to calculate optimum amount of
CO2 to reduce C in steel to a targeted
composition”
Carburization and Decarburization: Composition target
Ferrous Applications II 189
wei
gh
t %
<Alpha>
Carburization and Decarburization: Composition target
Ferrous Applications II 190
Viscosity Calculation: S+L mixtures (Einstein-Roscoe Eq.)
Einstein-Roscoe Equation (one of the most well-accepted
equation of viscosity for solid+liquid mixtures)
Viscosity (solid+liquid mixture) Viscosity(liquid) (1 solid fraction)-2.5
Original Einstein-Roscoe equation used ‘volume fraction of
solid’ instead of ‘solid fraction’ and a correction term for
morphology, but all these values are not very well-known for
general solids. We can simply use the solid fraction (wt fraction)
for this equation as an approximation.
This value can be calculated using the “Equilib” module at
a given system composition and temperature (Step-1).
Viscosity of liquid slag can be
calculated from “Viscosity”
module from slag composition
calculated from “Equilib” (Step-2)
Ferrous Applications II 191
Viscosity calculations “Step-1”: Composition of liquid slag
Ferrous Applications II 192
Viscosity calculations “Step-2”: Viscosity of liquid slag
Composition of liquid
slag from Equilib
Take these results
for next step
“Melts” database is for liquid slag
Ferrous Applications II 193
Viscosity calculations “Step-3”: Liquid + Solid mixture
Amount
of slag
Amount of solids
(100-amount of liquid)
Step-2
Einstein-Roscoe
Eq.
Ferrous Applications II 194
Thanks to FactSage Steelmaking Consortium Members
Developments of
• Thermodynamic database
• Process simulation model
Training for FactSage and Process simulation