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Ductile Iron Society T&O Meeting

Milwaukee, June 18-20 2008

UNDERSTANDING THEUNDERSTANDING THEUNDERSTANDING THEUNDERSTANDING THEUNDERSTANDING THE UNDERSTANDING THE FORMATION OF DROSS IN FORMATION OF DROSS IN DUCTILE IRON CASTINGSDUCTILE IRON CASTINGS

UNDERSTANDING THE UNDERSTANDING THE FORMATION OF DROSS IN FORMATION OF DROSS IN DUCTILE IRON CASTINGSDUCTILE IRON CASTINGSDUCTILE IRON CASTINGSDUCTILE IRON CASTINGSDUCTILE IRON CASTINGSDUCTILE IRON CASTINGS

Martin Gagné, Marie-Pierre Paquin, Pierre-Marie Cabanne

RIO TINTO Iron & Titanium – SorelmetalSorel-Tracy, CanadaFrankfurt, Germany

Dross slag & sand inclusions are the three major non metallic

DEFINITIONS:DEFINITIONS:DEFINITIONS:DEFINITIONS:Dross, slag & sand inclusions are the three major non-metallic

inclusions found in DI;

Drosses are endogenous while slag and sand inclusions areDrosses are endogenous while slag and sand inclusions are exogenous;

Drosses have a filamentary aspect while slag inclusions exhibit a osses a e a a e ta y aspect e s ag c us o s e b t ablocky appearance;

Magnesium silicate filaments (drosses) are forming within the iron during pouring (in the stream, in the pouring basin, in the gating system or during the first filling of the mold cavity),whereas slag is mainly originating from the magnesium treatment and theslag is mainly originating from the magnesium treatment and the residues from the furnace and the ladle.

EXAMPLES:EXAMPLES:EXAMPLES:EXAMPLES:

Slag and Sand Defects:

« C » area at high magnification

1= 44%SiO2, 52%MgO;1 44%SiO2, 52%MgO;

2= 53%SiO2 , 18%CaO, 16%MgO;

3 = 54%SiO2, 18%Al2O3, 10% CaO, 15%FeO

Slag & Sand Inclusions:

A= 54%SiO 17%MgO 18%CaO;

1

A= 54%SiO2, 17%MgO,18%CaO;

B= SiO2 100% sand;

C=

2

C 3


Slag and Sand Defects:


Dross Defects:

Analysis no. 1 2 3 4 5 6

MgO 25% 14 16 48 40 24

SiO2 56% 55 62 44 36 33

Al O 7% 5 8 5 6 1Al2O3 7% 5 8 5 6 1

CaO 0.5 - - - - -

MnO 5 23 11 - 3 8

FeO 4 3 2 2 16 31


Dross Defects:

EFFECT on MECHANICAL PROPERTIES:EFFECT on MECHANICAL PROPERTIES:EFFECT on MECHANICAL PROPERTIES:EFFECT on MECHANICAL PROPERTIES:

Ductility

20

22

16

18

gatio

n (%

)

10

12

14

Elon

8

10

7 9 11 13 15 17 19 21 23

Perlite Content (%)Perlite Content (%)


Low Ductility: Dross on Fracture Surface

Dross


Impact Energy: Dross on Fracture Surface

No Dross: 114 lb-ft With Dross: 52 lb-ftADI: un-notched Charpy specimens


Defect Rel. Fatigue Endurance

Fatigue Strength:

None 1.00Dross 0,54

Micro shrinkage. 0,73

Macro shrinkage 0,50

Chunk graph. 0,75

Anomalies 0,83

(Frauenhofer Institute / Refstie & Skaland – Vesta Group)

FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:

Ellingham diagram:


Binary Phase Slag (liq) + MgO

Sl (li 1) +

Slag (liq)Binary Phase

Diagram

MgO – SiO

Slag (liq) + SiO2

Slag (liq1) + Slag (liq2)

MgO – SiO2

SiO2 + MgSiO2

MgSiO2+

Mg2SiO4

MgO + Mg2SiO4


Thermodynamic simulations were carried out to determine the conditions for dross formationdetermine the conditions for dross formation

General Parameters:%S 0 010 & 0 020• %S : 0,010 & 0,020;

•%Si: 2,0 & 2,5; •%Mg: 0 04 0 06%;•%Mg: 0,04 – 0,06%; •Temp.: 1300 to 1500C; •Oxygen: 10 to 1000 ppm.yg pp

Simulation by FactSage software (developed at École Polytechnique de Montréal); this software assumesPolytechnique de Montréal); this software assumes equilibrium is reached.


Thermodynamic simulations were carried out to determine under which conditions dross would form

Parameters:• %S : 0,010 & 0,020; •%Si: 2,0 & 2,5; •%Mg: 0,04 – 0,06%; •Temp.: 1300 to 1500C;

•Oxygen: 10 to 1000 ppm to simulate turbulence!

Magnesium compounds formationFORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Magnesium compounds formation

%S: 0,010

%Si: 2 0%Si: 2,0

%Mg: 0.04 & 0.05

%O: 10, 100 & 200 ppm

Temperature: 1300-1500 C

FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Magnesium compounds formation

Magnesium Oxide with % Mg = 0 04 – 0 05

Magnesium compounds formation

0 04 % 0 05 %

Magnesium Oxide with % Mg = 0.04 – 0.05

0.05

0.06

on

0.05

0.06

on

0.04 % 0.05 %

0.03

0.04

crea

ted

in 1

00g

of ir

o0 02

0.03

0.04

cre

ated

in 1

00g

of ir

0.00

0.01

0.02

1250 1300 1350 1400 1450 1500 1550

g of

MgO

0.00

0.01

0.02

1250 1300 1350 1400 1450 1500 1550

g of

MgO

1250 1300 1350 1400 1450 1500 1550

temperature (C)

0.05% Mg et 10ppm O 0.05%Mg et 100ppm O 0.05%Mg et 200ppm O

50 300 350 00 50 500 550

température (C)

0.04%Mg et 10ppm O 0.04%Mg et 100ppm O 0.04%Mg et 200ppm O

FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Magnesium compounds formationMagnesium compounds formation

Magnesium Silicite (MgxSiy) with % Mg = 0.04 – 0.05, 2,0% Si

0 04 % 0 05 %

Magnesium Silicite (MgxSiy) with % Mg 0.04 0.05, 2,0% Si

0.07

0.08

n

0.07

0.08

n

0.04 % 0.05 %

0 03

0.04

0.05

0.06

crea

ted

in 1

00g

of ir

on

0 03

0.04

0.05

0.06

crea

ted

in 1

00g

of ir

on

0.00

0.01

0.02

0.03

1250 1300 1350 1400 1450 1500 1550

g of

dro

ss c

0.00

0.01

0.02

0.03

1250 1300 1350 1400 1450 1500 1550

g of

dro

ss c

1250 1300 1350 1400 1450 1500 1550

temperature (C)


1250 1300 1350 1400 1450 1500 1550

temperature (C)



M i d 1° t f d i l tiMagnesium compounds: 1° step of dross simulation

Magnesium Sulphide with % Mg = 0.04 – 0.05, 0,010% S

0 04 % 0 05 %

Magnesium Sulphide with % Mg 0.04 0.05, 0,010% S

0.02

0.02

0.02

f iro

n (g

)

0 01

0.02

0.02

0.02

de 1

00g

de

0.04 % 0.05 %

0.02

0.02

0.02

0.02

S cr

eate

d in

100

g of

0 01

0.01

0.01

0.01

0.01

MgS

form

é à

part

ir d

mét

al (g

)

0.02

0.02

0.02

1250 1300 1350 1400 1450 1500 1550

g of

MgS

0.00

0.00

0.00

0.01

1250 1300 1350 1400 1450 1500 1550

mas

se d

e M

temperature (°C)


température (C)



M i d 1° t f d i l ti

“R id l F ” M i ith % M 0 04 0 05

Magnesium compounds: 1° step of dross simulation

0 04 % of Mg 0 05 % of Mg

“Residual = Free” Magnesium with % Mg = 0.04 – 0.05

0.035

0.040

0.030

0.035

0.04 % of Mg 0.05 % of Mg

0.015

0.020

0.025

0.030

% re

sidu

al M

g

0.015

0.020

0.025

% re

sidu

al M

g

0.000

0.005

0.010

1250 1300 1350 1400 1450 1500 15500.000

0.005

0.010

1250 1300 1350 1400 1450 1500 1550temperature (C)


1250 1300 1350 1400 1450 1500 1550

temperature (C)


FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Effect of TemperatureEffect of Temperature

% S: 0,001

% Si: 2 0% Si: 2,0

% Mg: 0,04

O 100 300 500 700 &1000Oxygen: 100, 300, 500, 700 &1000 ppm

Temperature: 1300-1500 C

Effect of TemperatureFORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:

Dross formation vs Temperature for 0.04% Mg, 2% Si & 100ppm O2

Effect of Temperature

2.50E-01

pp 2

1.50E-01

2.00E-01

s

1.00E-01

g de

dro

ss

MgOSiO2

0.00E+00

5.00E-02

g

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500T (C)

g-MgO(s) g-SiO2(s4) g-MgSiO3(s3) g-Mg2SiO4(s) g-MgS(s)

FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Effect of Temperature



2.50E-01

pp 2

1.50E-01

2.00E-01

ss

Mg2SiO4

1.00E-01

g de

dro

s

g2 4

0 00E+00

5.00E-02

MgO0.00E+00

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500T (C)


FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Effect of Temperature:


Effect of Temperature:

2.50E-01

pp 2

1.50E-01

2.00E-01

ss

1.00E-01

g de

dro

s

Mg2SiO4MgO

0.00E+00

5.00E-02

g2 4MgO

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500T(C)





2.50E-01

pp 2

1.50E-01

2.00E-01

1.00E-01

gram

me

Mg2SiO4M SiO

0 00E+00

5.00E-02

Mg2SiO4MgSiO3

0.00E+001300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500

T (C)





2 00E 01

2.50E-01

pp 2

1.50E-01

2.00E-01

me MgSiO3

1.00E-01

gram

m

Mg2SiO4

g 3

0.00E+00

5.00E-02

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500

g2 4

SiO21300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500

T (C)


FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Effect of Temperature: SummaryEffect of Temperature: Summary

2.50E-01


2.50E-01


SummarySummary5.00E-02

1.00E-01

1.50E-01

2.00E-01

g de

dro

ss

Mg2SiO4

5.00E-02

1.00E-01

1.50E-01

2.00E-01

g de

dro

ss

MgOSiO2




0.00E+001300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 150

T (C)


MgO0.00E+00

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500T (C)


1.00E-01

1.50E-01

2.00E-01

2.50E-01

gram

me MgSiO3

1.00E-01

1.50E-01

2.00E-01

2.50E-01

gram

me

1.00E-01

1.50E-01

2.00E-01

2.50E-01

g de

dro

ss

pp 2

0.00E+00

5.00E-02

1.00E 01

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 150T (C)


Mg2SiO4

SiO20.00E+00

5.00E-02

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500T (C)


Mg2SiO4MgSiO3

0.00E+00

5.00E-02

1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500T(C)


Mg2SiO4MgO

At high Temperature, dross level is similar

FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Effect of Oxygen Content (turbulence)Effect of Oxygen Content (turbulence)

% Sulphur: 0.010 0.020

%Magnesium: 0.040 0.060

% Silicon: 2.00 2.50

°C Temperature: 1300 and 1500

ppm Oxygen: from 10 to 1000


2.50E-01

2.00E-01

0.01%S, 0.04% Mg, 2% Si & 1300°C

1.50E-01

ross

1.00E-01g of

D

Mg2SiO3

5.00E-02Mg2SiO4

MgOSiO2

0.00E+000.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O

MGO SiO2 MgSiO3 Mg2SiO4 MgS

MgO


2.50E-01

2.00E-01

0.01%S, 0.04% Mg, 2% Si & 1500°C

1.50E-01

dros

s

1.00E-01g of

d

5.00E-02

MgO

Mg2SiO4

0.00E+000.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O



2 50E 01

2.00E-01

2.50E-01

0.02%S, 0.06% Mg, 2.5% Si & 1300°C

1.50E-01

ross

1.00E-01g of

d

Mg2SiO4

0 00E 00

5.00E-02 MgOMg2SiO3

0.00E+000.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O



2.50E-01

2.00E-01

0.02%S, 0.06% Mg, 2.5% Si & 1500°C

1.50E-01

Dro

ss

1.00E-01g of

D

Mg2SiO4

5.00E-02 MgO

0.00E+000.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O


FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:FORMATION, EXPLANATION & SIMULATION:Effect of Oxygen Content: Summary

2.00E-01

2.50E-01

0.02%S, 0.06% Mg, 2 5% Si & 1300°C

2.00E-01

2.50E-01

0.01%S, 0.04% Mg,

Effect of Oxygen Content: Summary

1.00E-01

1.50E-01

g of

dro

ss

Mg2SiO4

2.5% Si & 1300°C

1.00E-01

1.50E-01

g of

Dro

ss

2% Si & 1300°C

Mg2SiO3

More Dross at low O2

0.00E+00

5.00E-02

0.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O

MgOMg2SiO3

0.00E+00

5.00E-02

0.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O

Mg2SiO4Mg2SiO3

MgOSiO2

Less Dross at

2.00E-01

2.50E-01

0.02%S, 0.06% Mg, 2 5% Si & 1500°C

2.00E-01

2.50E-01

0.01%S, 0.04% Mg, 2% Si & 1500°C

MGO SiO2 MgSiO3 Mg2SiO4 MgSMGO SiO2 MgSiO3 Mg2SiO4 MgSLess Dross at

high Temp

More Dross with

1.00E-01

1.50E-01g

of D

ross

Mg2SiO4

2.5% Si & 1500 C

1.00E-01

1.50E-01

g of

dro

ss

high S, Mg, Si

0.00E+00

5.00E-02

0.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O


MgO

0.00E+00

5.00E-02

0.001 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

%O


MgO

Mg2SiO4

CONCLUSIONS:CONCLUSIONS:CONCLUSIONS:CONCLUSIONS:

Formation of dross is mainly controlled by oxygen content; the l l f i d t th t t l flevel of oxygen required suggests that an external source of oxygen is needed: turbulence!

Dross is mainly a “mixture” of magnesium silicates;Dross is mainly a “mixture” of magnesium silicates;

Dross formation is favored by low pouring temperature, turbulence, high %Mg and high %Si;high %Mg and high %Si;

If all other parameters are kept under control, the effect of pouring temperature is minimized;temperature is minimized;

Sulphur, at low level, does not interact with dross formation.

Composition of dross changes with temperatureComposition of dross changes with temperature.

Thanks!Thanks!Thanks!Thanks!Thanks!Thanks!

Gracias!Gracias!

Thanks!Thanks!

Gracias!Gracias!Gracias!Gracias!

Merci!Merci!

Gracias!Gracias!

Merci!Merci!Merci!Merci!Merci!Merci!

Martin Gagné, Marie-Pierre Paquin, Pierre-Marie Cabanne

RIO TINTO Iron & Titanium – SorelmetalSorel-Tracy, CanadaFrankfurt, Germany

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