Post on 16-Jan-2022
SFB 761 „Stahl ab initio“
25.08.2009„MSE“ Berlin
Uni. Prof. Dr.-Ing. D. SenkDipl.-Ing. A. Lob
Smelting and Soldification of Fe-Mn-C Steel
Senk, Lob
SFB 761 „Stahl ab initio“ Subarea B1
Smelting and Solidification of Fe-Mn-C SteelSubtask: Manganese Vaporisation
Picture: A. Lob
25.08.09, No. 1
Senk, Lob
Smelting and Solidification of Fe-Mn-C SteelSubtask: Manganese Vaporisation
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 2
1. Presentation of the System Fe-Mn-C
2. a. Calculation of the Vapour Pressure for the Sytem Fe-Mn;b. Temperature Dependence
3. Experimentsa. Melting Furnaceb. Parameters for Manganese Vaporisationc. Pressure Dependenced. Atmosphere Dependencee. Temperature Dependece
4. Outlook for further Experimentsa. Thermal Convection
5. Abstract
Senk, Lob
Choice of chemical composition:SFE depending on forming mechanism- TRIP-Steel
TRansformationInduced Plasticity (I IV V)
- TWIP-Steel Twinning Induced Plasticity (II III VI VII)
→ high contents of manganese (high [Mn]-activity) means high vaporisation losses
SFB 761 „Stahl ab initio“ Subarea B1
Mechanism Map for SFB 76125.08.09, No. 3
Senk, Lob
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 4
MnMn app ⋅=*MnMnMn xa ⋅= γ
056.0027.0)1(352.0ln 2 ±+−⋅= MnMn Xγ
[3]16001.3
[2]16001.3
[1]15901.38
LiteratureTemperature (°C)Activity coefficient of
Mn
[1] Hultgren, R.; Orr, R. L.; Anderson, P. D.; Kelly, K. K.: Selected Values of Thermodynamik Properties of Metals and Alloys, John Willey, New York, London (1963) pp. 726-732
[2] Bužek, Z.; Schlinderova, V.: Freiberger Forschungsheft B, 117 (1969) pp. 75-90[3] Sigworth, G. K.; Elliott, J. F.: Metal Science, 8 (1974) pp. 298-310
Distribution of iron and manganese activities in the system Mn-Fe (Thermo®-Calc)
vapour pressure pure Mn = 48,7 mbar vapour pressure pure Fe = 0,046 mbar
vapour pressure of the system Fe-Mn
→ pressure below 14,85 mbar would increase manganese vaporisation
pMn* (Fe-Mn) = 14,85 mbar ( chemical composition I)
Calculations; Pressure Dependence
Senk, LobCalculations; Temperature Dependence
SFB 761 „Stahl ab initio“ Subarea B1
Manganese vs. Mn pressure for different Temperatures in the system Mn-Fe (Thermo®-Calc)
→ high temperatures let increase Mn pressure and the vaporisation losses
25.08.09, No. 5
Senk, Lob
Vacuum-Induction-Furnace 4 at IEHK
frequency: 3 kHzmaximum power input: 150 kWvacuum: ≥ 3·10-3 mbar capacity: 100 kgspecial features: adjustable atmosphere
programmable temp.charging during vacuum
features: - online and clean measurem. = Hydris®-System
- steam condenser
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 6
Experiments; Melting Furnace
→ production of clean high manganese steel→ adjustment of parameters avoiding
high manganese losses
Senk, Lob 25.08.09, No. 7
( ) 543213.210
nnliq
nnn aCTTCpCAmdt
dm+−++⋅=
Experiments; Parameters
Parameters:- melting weight (m)- reaction area (A)- pressure (p)- temperature (T)- activity (a)- convection- atmosphere
Adjustment of the following parameters to decrease manganese losses:
Reasons to decrease manganese losses:
- the manganese dust can damage the vacuumtechniques, see figure
- high manganese losses cause high costs of alloying materials(electrolyt manganese = 4700 Euro / t; stand July 09)
SFB 761 „Stahl ab initio“ Subarea B1
Contamination as a result of manganesevaporisation in the VI 4
→ reduce manganese losses to protect vacuum techniquesand to reduce raw material costs
→ reduce manganese losses by adjustment of melting parameters
Senk, Lob
Manganese losses for different pressures vs. time
→ other parametershave to be constantfor all experiments!
* master thesis D. Rzehak
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 8
Experiments; Pressure Dependence
Parameters:- melting weight (m)- reaction area (A)- pressure (p)- temperature (T)- activity (a)- convection- atmosphere
→ experiments show a contrary pressure dependence→ possible: the low pressure decreases the convection above the melt
and decreases the vaporisation of manganese atoms
Senk, Lob
pressure 800 mbar pressure 10 mbar
boiler of VI 4 boiler of VI 4
brown deposit
- highly flammable incontact with air
- no melting view“ blind-melting”
black deposit
- lowly flammable incontact with air
- melting view≥ 400 mbar sufficient≥ 150 mbar low vaporisation
EDX at GFE
EDX at GFE
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 9
Experiments; Pressure Dependence
Parameters:- melting weight (m)- reaction area (A)- pressure (p)- temperature (T)- activity (a)- convection- atmosphere
→ pressure is essential for melting
Senk, Lob
Temperatur
[Mn]-Ist20
21
22
23
24
25
0 20 40 60 80 100
Zeit (min)
[Mn-
Geh
alt (
Gew
.-%)
10001100120013001400150016001700
Tem
pera
tur (
°C)
Temperatur
[Mn]-Ist
20
21
22
23
24
25
80 100 120 140
Zeit (min)
[Mn]
-Geh
alt (
Gew
.-%
)1000
1100
1200
1300
1400
1500
1600
Tem
pera
tur (
°C)
dm/dt (Ar.) = 1,08 Gew.-%/hcomplete = 1,79 Gew.-%
dm/dt (air) = 1,04 Gew.-%/hcomplete = 0,85 Gew.-%
[Mn]-content vs. timefor argon atmosphere
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 10
Experiments; dependence of atmosphere
Parameters:- melting weight (m)- reaction area (A)- pressure (p)- temperature (T)- activity (a)- convection- atmosphere
[Mn]-content vs. time at air
→ no effect of the atmosphereon manganese vaporisationcan be observed
Senk, Lob
Temperature
[Mn]-current
p=800mbar
[Mn]-setpoint
21
21,5
22
22,5
23
23,5
24
24,5
25
0 5 10 15 20 25
Time (min)
Man
gane
se c
onte
nt (w
t.%)
1300
1350
1400
1450
1500
1550
1600
1650
1700
Tem
pera
ture
(°C
)
[Mn]-setpointTemperature
p=10mbar
[Mn]-current
21
21,5
22
22,5
23
23,5
24
24,5
25
0 5 10 15 20 25
Time (min)
Man
gane
se c
onte
nt (w
t.%)
1300
1350
1400
1450
1500
1550
1600
1650
1700
Tem
pera
ture
(°C
)
[Mn]-content vs. time for 1600 °C
dm/dt (T = 1500 °C ± 30 K) = 2,16 Gew.-%/h= 0,9 Gew.-% (complete)
dm/dt (T = 1600 °C ± 30 K) = 4,32 Gew.-%/h= 1,8 Gew.-% (complete)
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 11
Experiments; temperature dependence
Parameters:- melting weight (m)- reaction area (A)- pressure (p)- temperature (T)- activity (a)- convection- atmosphere
[Mn]-content vs. time for 1500 °C
→ high melting temperatureslet increase the manganeselosses in the melt
Senk, Lob
200 mm
400 mm
200 mm
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 12
Experiments; Convection (thermal)
Parameters:- melting weight (m)- reaction area (A)- pressure (p)- temperature (T)- activity (a)- convection- atmosphere
Further experiments for the determination of manganesevaporisation in the system
Fe-Mn-C:- Application of a cover to avoid
cold sources
Condenser in the VI 4 at IEHK
→ elimination of thermal convectionabove the melt to decrease manganese losses
Senk, Lob 25.08.09, No. 13
SFB 761 „Stahl ab initio“ Subarea B1
Abstract
- Melting in the System Fe-Mn-C with [Mn]- Contents of 12-30 wt.% is leading to Manganese Losses
- Manganese Losses depends on the high Vapour Pressure
- the Vapour Pressure depends on Parameters like Temperature, Pressure, Activity, Convection
- Experiments show a contrary Pressure Dependence
- Atmosphere has no effect on Manganese Losses
- high Temperatures let increase the Manganese Losses
- further Experiments should shoe the Effect of thermal Convection onManganese Vaporisation in the System Fe-Mn-C
Senk, Lob
SFB 761 „Stahl ab initio“ Subarea B1
25.08.09, No. 14
Thank you for your attention
Institute for Ferrous Metallurgy RWTH Aachen University
Univ.- Prof. Dr.- Ing. D. Senk (senk@iehk.rwth-aachen.de)
Dipl.- Ing. A. Lob (lob@iehk.rwth-aachen.de)
www.iehk.rwth-aachen.de
http://abinitio.iehk.rwth-aachen.de
Senk, Lob
Mn-Verdampfung
(atm) LuftT=1600 °Cp = 1 bar
I, Magma 1
(atm) ArgonT = 1600 °Cp = 0,8 barI, Versuch 8
(T) T = 1600 °Cp = 0,8 barI, Versuch 8
(T) T = 1500 °Cp = 0,8 bar
I, Versuch 14
(p) T = 1500 °Cp = 0,8 bar
I, Versuch 14
(p) T = 1500 °Cp = 0,01 barI, Versuch 16
(a) T = 1500 °Cp = 0,01 bar
III, Versuch 19
(a) T = 1500 °Cp = 0,01 bar
VIII, Versuch 25
(a) T = 1500 °Cp = 0,01 barI, Versuch 16
(k) T = 1500 °Cp = 0,01 bar
I, Versuch x (Spülstein)
(k) T = 1500 °Cp = 0,01 bar
I, Versuch x (Spülst., Deckel)
(p) T = 1500 °Cp = 0,4 bar
I, Versuch 20