Efeito da Pre Inoculação com SiC

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AFS Transactions 01-064 (Page 1 of 15)
Pre-Inoculation Effect of SiC in Thin-Wall Ductile Iron Production
K.W. Copi,
EXOLON ESK, Pembroke, Georgia
Y.S. Lerner and N. Laukhin
University of Northern Iowa, Cedar Falls, Iowa
Copyright 2001 American Foundry Society
ABSTRACT
Pre-inoculation effect of SiC furnace additions on microstructure, magnesium recovery, and castability in thin wall
ductile iron plates were studied and compared with alternative FeSi75.
Obtained results showed that pre-inoculation with SiC provides higher residual magnesium and better magnesium
recovery (61.7% for SiC vs. 55.3% for FeSi75) when the same amount of FeSiMg-masteralloy was used. When the amount
of FeSiMg-masteralloy for experimental heats using SiC was reduced by 11% the residual magnesium remained higher
(0.033% vs. 0.032%) than in experimental heats using FeSi75 and standard amount of FeSiMg. Chill tendency in thin wall
ductile iron plates was lower even in those experimental heats using SiC with residual magnesium higher 4.1% than in
experimental heats using FeSi75 with the same carbon equivalent. Castability was found to be equal for both materials.
INTRODUCTION
Previous research [1] aimed to investigate the influence of pre-inoculation effect of different grades of SiC in
comparison with FeSi75 on microstructure and solidification behavior of gray iron, showed that 85 - 90% metallurgical SiC
gave the best results.
Studies [2,3] have been done to assess pre-inoculation with SiC by evaluating the cooling curves, structure and
shrinkage tendency of ductile iron as a function of holding time in comparison with FeSi75. It was found that 97-98%
crystalline SiC produced the best pre-inoculation effects in ductile iron.
A literature review has revealed the fact that the published information on SiC pre-inoculation does not involve
studies on thin wall ductile iron castings. At the same time, the advancement in production of thin wall iron castings, for an
overall weight reduction of industrial parts, particularly in powertrain components, plays significant role in automotive and
other industries [4].
The objective of this study was to investigate pre-inoculation effect of SiC as furnace additions in comparison with
FeSi75 additions by assessing fluidity/castability, microstructure of thin wall ductile iron plates, and overall magnesium
recovery in the process of ductile iron production.
EXPERIMENTAL PROCEDURES
Charging and Melting of Base Iron. Base iron for experimental heats was produced in a medium frequency coreless
induction furnace from a charge mix consisted of nodular grade pig iron, ductile iron returns, AISI 1010 steel punchings, and
carbon riser. SiC (30x50mesh) containing 67.9% silicon and 30% carbon or FeSi75 (3/8x12 mesh) containing 76% silicon
were used as furnace additions. The molten base iron was tapped from the furnace into the flow-through Mg-reaction
chamber, containing treatment additions.
Treatment and Inoculation of Base Iron. The flow-through technique (Figure 1) was used to treat base iron with FeSiMg-
masteralloy (3/8x18 mesh), containing 3.65% Mg and 45.49% Si. Along with the magnesium- masteralloy, FeSi75 in the
standard amount of 0.75% (1.87 lb) was placed in the flow-through reaction chamber. The tapping and treatment
temperatures, percentage of pre-inoculation additions (FeSi75 or SiC), masteralloy additions (FeSiMg), and inoculant
additions (FeSi75) are shown in Table 1. No late additions (stream or mold) of any inoculant were used.
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AFS Transactions 01-064 (Page 3 of 15)
Figure 1. The schematic showing tapping of base iron from the induction furnace and the flow-through
Mg-treatment process: 1--coreless induction furnace; 2--base iron; 3--charging window; 4--reaction chamber;
5--FeSiMg-treatment alloy; 6--inoculant; 7--treated iron; 8--ladle.
The aim of the first series of experiments was to set the baseline of iron quality, when using FeSi75 in amount of
0.75% (1.875 lb.) as furnace additions. In these series, FeSiMg-masteralloy and FeSi75 inoculant were placed in the flow-
through reaction chamber.
The second series of experiments investigated pre-inoculation effect of SiC furnace additions in amount of 0.86%
(2.15 lb.), which ensured the same silicon content in the base iron as when FeSi75 was used. The standard additions of 1.8%
(4.5 lb.) FeSiMg-masteralloy and FeSi75 inoculant in the amount of 0.75% (1.87 lb.) were placed in the flow-through
reaction chamber. Magnesium recoveries were found to be considerably higher, than in the baseline heats, leading to much
higher than anticipated residual magnesium levels (Table 2).
Table 2. Experimental parameters of pre-inoculation experiments after Mg-treatment
Iron temperature,
°F/°C
Chemical composition after treatment, %
Index Series of experiment After
treatment
Before
pouring CE,% C Si Mn P S Mg
1
Pre-inoculation with
FeSi75 (standard additions
of FeSiMg)
2598/
1425
2505/
1373
4.60 3.66 2.71 0.22 0.016 0.007 0.032
2
Pre-inoculation with SiC
added into the furnace
(standard additions of
FeSiMg)
2532/
1388
2432/
1333
4.65 3.85 2.50 0.28 0.023 0.010 0.039
3
Pre-inoculation with SiC
added into the furnace
(reduced by 11% additions
of FeSiMg)
2581/
1416
2566/
1407
4.67 3.85 2.74 0.38 0.022 0.010 0.033
4
Pre-inoculation with SiC
added into the furnace
(reduced by 22% additions
of FeSiMg)
2592/
1421
2546/
1401
4.70 3.91 2.68 0.42 0.022 0.010 0.029
AFS Transactions 01-064 (Page 4 of 15)
Therefore, the third and the fourth series of experiments also investigated SiC pre-inoculation capabilities as furnace
additions in the same amount of 0.86% (2.15 lb.) as in series two, but the quantity of FeSiMg was reduced by 11% from
1.8% (4.5 lb.) to 1.6% (4.0 lb.) in the third series of experiments, and by 22% from 1.8% (4.5 lb.) to 1.4% (3.5 lb.) in fourth
series of experiments, attempting to produce a final iron with residual Mg content closer to that made in series one with
FeSi75. For consistency, each series of experiments was repeated at least three times.
Experimental Molds and Test Castings. Test castings for this study were poured in no-bake, un-coated sand molds,
assembled of seven 7 ¼" diameter and ¾" thickness cores, made of silica sand mesh 57x62. Figure-2 illustrates the core
boxes and the experimental cores. The cores were stacked together with pouring cup glued on the top of the assembly
(Figure 3). The typical test casting consisted of three levels of plates, creating an "experimental tree" (Figure 4). Each level
comprised of four 2" (50 mm) long and1" (25mm) wide plates with the following thickness: 0.039" (1 mm), 0.059" (1.5
mm), 0.079" (2 mm), and 0.118" (3 mm).
Tapping and Pouring. The liquid iron was tapped into the flow-through chamber containing FeSiMg-masteralloy and
FeSi75 inoculant and then teemed into the ladle. Average time of treatment was 31 seconds. Then treated iron was poured
into three experimental molds. Average pouring time of the first mold was approximately 4 sec.; average time of pouring all
three experimental molds was 21.5 sec.
Chemical Composition of Base and Treated (Ductile) Irons. The carbon, silicon, and carbon equivalent values, obtained
from a thermal analysis system, allowed adjusting chemical composition of base iron before tapping, if necessary.
Simultaneously with pouring, thermal analysis system sample and right after treatment, chill buttons were poured to evaluate
the chemical composition of base and treated (ductile) irons via spectrometer. The magnesium recovery (Mgr) was calculated
using the following equation [5]:
(0.76 x ∆S + Mg2) x 100 Mgr =
Mg1
, %
where:
∆S –difference between the sulfur content in the base iron and the treated metal, wt. %; Mg1 – total magnesium additions,
wt. %; Mg2 -residual magnesium content, wt. %.
The carbon equivalent (CE) was calculated using the equation [6]:
 CE = C+ 0.31Si , %
where:
C– residual carbon content, wt. %; Si– residual silicon content, wt. %.
Cooling curves of base iron obtained from the thermal analysis system used to study solidification behavior of base
irons pre-inoculated with FeSi75 or SiC.
Castability of Ductile Iron Thin Wall Plates. As soon as experimental molds were shaken out, the castability of thin wall
ductile iron plates was studied using a ruler with metric and inch scales. The distance from the ingate up to furthest end of
each solidified plate was considered as the castability/fluidity criterion.
Chill Tendency in Ductile Iron Thin Wall Plates. The thin wall plates at each level were separated from the riser and
marked according to level and experimental tree identification. The plates, taken from the middle level of each experimental
tree, were broken in the middle of the plates to study chill depth on the fractures. The chill area of each plate, usually located
at the edges of the fracture, was measured with a rule as a length of chill from the edge toward the center, and calculated in
percentage as a ratio of the chill to the whole fracture length.
Microstructure Analysis. The same plates that were taken for chill tendency evaluation were used for microstructural analysis.
Plates taken from the middle level of each experimental tree were stacked together, in sequence, according to their thickness
(from thinnest to thickest). This set of plates, representing each experimental tree, was then mounted in bakelite pre-molds,
polished and marked for identification number.
AFS Transactions 01-064 (Page 5 of 15)
The microstructure analysis was conducted utilizing both optical microscope and an imaging system. The first stage
of this evaluation was to determinate graphite morphology at magnification X200 on an unetched surface using the image
analysis system. The periphery and center of each plate were studied, evaluating the following parameters: area of graphite,
nodule count, and nodularity.
The second stage comprised of evaluation of metallic matrix at magnification X200 using optical microscope.
Before this evaluation, all mounted sets were etched for 3 seconds, using 4% Nital as an etching reagent. On this stage, the
ferrite/pearlite ratio and iron carbides percentage were evaluated at the periphery and the center of each sample.
RESULTS AND DISCUSSIONS
Residual Magnesium and Magnesium Recovery. Average values of residual magnesium and calculated magnesium
recoveries are given in Figure 5. As can be seen, the highest residual magnesium (0.039%) was obtained in heats using SiC
and standard additions of FeSiMg-master alloy, while in experimental heats using FeSi75 pre-inoculant and standard
additions of FeSiMg-masteralloy residual magnesium averaged 0.032%. Even using 11% less FeSiMg-masteralloy added
(1.6%), the iron pre-inoculated with SiC still contained 4.1% higher ( 0.033%) residual magnesium than in heats with FeSi75
and standard additions of FeSiMg-masteralloy. In heats pre-inoculated with SiC and treated with 1.4% FeSiMg-masteralloy
(reduced by 22%), residual magnesium content was 0.029%.
Magnesium recovery in experimental heats using SiC pre-inoculant and standard FeSiMg-masteralloy additions was
the highest (61.7%) over all experimental heats. When the SiC pre-inoculant and reduced additions of 1.6% and 1.4% of
FeSiMg-masteralloy were applied, the magnesium recovery observed still higher (58% for both cases) than in those heats
using FeSi75 and standard FeSiMg-masteralloy additions, where magnesium recovery was less (55.3%). Obtained data
obviously demonstrated that pre-inoculation with SiC improves magnesium recovery.
A
B
Figure 2. Core boxes (A) and cores (B) used for production of experimental molds.
AFS Transactions 01-064 (Page 6 of 15)
Figure 3. Experimental mold for pouring thin wall ductile iron plates.
Figure 4. Experimental thin wall ductile iron casting with the gating system.
AFS Transactions 01-064 (Page 7 of 15)
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M
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%
B
1 2 3 4
Figure 5. Average residual magnesium (A) and magnesium recovery (B) in thin wall ductile iron plates pre-inoculated
with SiC and FeSi75: 1- pre-inoculated with FeSi75 and treated with standard FeSiMg (1.8% / 4.5 lb.) additions;
2- pre-inoculated with SiC and treated with standard FeSiMg (1.8% / 4.5 lb.) additions;
3- pre-inoculated with SiC and treated with reduced FeSiMg (1.6% / 4.0 lb.) additions;
4- pre-inoculated with SiC and treated with reduced FeSiMg (1.4% / 3.5 lb.) additions.
In fact, when iron was pre-inoculated with SiC, magnesium recovery was 61.7%, and 55.3% when iron was pre-inoculated
with FeSi75 with the same amount of FeSiMg-masteralloy.
Castability Evaluation. The average results of castability in thin wall ductile iron using FeSi75 and SiC, and treated with
standard and reduced additions of FeSiMg-master alloy, are shown in Figure 6. As can be seen, experimental ductile iron
plates with 0.059" (1.5mm), 0.079" (2mm), and 0.118" (3mm) thickness were completely filled in all tests. Thereby the main
emphasis of this evaluation was to evaluate castability of 0.039" (1mm) plates. Better castability was found in those heats
using SiC with both reduced FeSiMg-masteralloy additions 1.6% (4.0 lb.) and 1.4% (3.5 lb.), and also in heats using FeSi75
with standard FeSiMg-masteralloy additions 1.8% (4.5lb.). Lower castability was found in the heats using SiC pre-inoculant
with the standard additions of FeSiMg-masteralloy 1.8% (residual magnesium content was 0.039%).
Chill Tendency Evaluation. The average results of the chill depth in fracture of thin wall ductile iron plates, pre-inoculated
with FeSi75 and SiC, and treated with standard and reduced additions of FeSiMg-masteralloy are shown in Figure 7. It was
found that all 1mm plates had white fracture, which was evidence of complete chill, regardless of materials used in the
furnace, final chemistries, pouring temperatures, or amount of FeSiMg-masteralloy additions used. Similar to the castability
results, the chill depth in 1.5-mm plates (varied from 52% to 76%), 2-mm plates (varied from 40% to 48%), and 3-mm plates
(varied from 20% to 32%), was the lowest when SiC was added in the furnace with lower 1.6%, or 1.4% FeSiMg additions,
or when FeSi75 was used with the standard FeSiMg additions. Those heats, where SiC used in the furnace with the standard
1.8 % (4.5 lb.) additions of FeSiMg-masteralloy, resulted in higher residual magnesium, tended to also have higher
concentration of iron carbides: chill depth was subsequently in 1.5-mm plates-76%, in 2-mm plates-52%,and in 3-mm
plates-32%, as expected. This may be explained as a result of excessive residual magnesium served as an iron carbides
stabilizer in ductile iron pre-inoculated with SiC.
AFS Transactions 01-064 (Page 8 of 15)
Microstructure Evaluation. Area of graphite, nodules count, and nodularity were evaluated during the first stage of
microstructural analysis. The second stage of microstructural analysis comprised of evaluating metallic matrix: iron carbides
and ferrite/pearlite ratio.
Graphite morphology. Results of this study are presented in Figures 8 and 9 that illustrate average nodule count and
area of graphite in plates with thickness 1.5; 2 and 3 mm. Data obtained on 1 mm plates has been disregarded due to
significant amounts of iron carbides in their structure.
As can be seen (Figure 8), all 1.5 mm plates had the highest and 3 mm plates had the lowest nodule count regardless
of the type of inoculant and amount of FeSiMg masteralloy used. The nodule count at the edges of the plates was always
found higher than in the center of the plates. However, ductile iron plates, pre-inoculated with SiC and treated with reduced
additions of FeSiMg (1.4% / 3.5 lb) with residual magnesium 0.029%, produced the highest nodule count. The lowest nodule
count was found in ductile iron plates pre-inoculated with FeSi75 and SiC and treated with standard additions of FeSiMg
(1.8% / 4.5 lb) having residual magnesium 0.032% and 0.039% respectively. In ductile iron plates pre-inoculated with SiC
and treated with reduced additions of FeSiMg (1.6% / 4.0 lb) nodule count was intermediate.
Area of graphite in thin wall ductile plates (Figure 9) was always higher in 3 mm plates. The highest area of
graphite was observed in plates pre-inoculated with SiC and treated with reduced additions of FeSiMg (1.6% / 4.0 lb). Thin
wall ductile plates pre-inoculated with FeSi75 or SiC and treated with standard additions of FeSiMg (1.8% / 4.5 lb) had the
lowest area of graphite.
Nodularity in all experimental samples, regardless of the thickness of plates, type of pre-inoculant used, and amount
of FeSiMg-masteralloy added, was more than 95%.
Metallic matrix. Percentage of iron carbides (Figure 10) in 1-mm plates in all series of experiments was much
higher (varied from 57 to 42%) than in 1.5, 2, 3-mm plates. In all 2-mm and 3-mm ductile iron plates, regardless type of pre-
inoculant and amount of FeSiMg-master alloy, inverse chill along the center of fracture was found. In plates pre-inoculated
with SiC and treated with standard FeSiMg additions the percentage of iron carbides was the highest, having the highest
residual Mg. The lowest iron carbides content has been found in those heats pre-inoculated with SiC and treated with 1.6%
and 1.4% FeSiMg-masteralloy additions.
The percentage of ferrite (Figure 11) in metallic matrix was the highest in 3-mm plates and the lowest in 1-mm
plates, regardless which pre-inoculant was used. In plates pre-inoculated with FeSi75 the percentage of ferrite was higher in
comparison with thin wall plates pre-inoculated with SiC and treated with the same amount of FeSiMg-master alloy. All
experimental heats, where iron was pre-inoculated with SiC and treated with reduced FeSiMg-masteralloy additions (1,6% or
1.4%) had almost the same ferrite content as observed in ductile iron plates pre-inoculated with FeSi75 and treated with the
standard FeSiMg additions.
AFS Transactions 01-064 (Page 9 of 15)
0
10
20
30
40
50
60
 Top Middle Bottom
L
e
n
g
th
 o
f 
p
la
te
, 
m
m
Pre-inoculated with FeSi75, standard (1.8%/4.5 lb.) additions of FeSiMg (0.032% residual Mg)
Pre-inoculated with SiC, standard (1.8%/4.5 lb.) additions of FeSiMg (0.039% residual Mg)
Pre-inoculated with SiC, reduced (1.6%/4.0 lb.) additions of FeSiMg (0.033% residual Mg)
Pre-inoculated with SiC, reduced (1.4%/ 3.5 lb.) additions of FeSiMg (0.029% residual Mg)
Figure 6. Average castability of 1-mm ductile iron plates pre-inoculated with FeSi75 and SiC.
AFS Transactions 01-064 (Page 10 of 15)
0
10
20
30
40
50
60
70
80
1.5 2 3
Thickness of plates, mm
C
h
ill
e
d
 a
re
a
, 
%
Pre-inoculated with FeSi75, standard (1.8%/4.5 lb.) additions of FeSiMg (0.032% residual Mg)
Pre-inoculated with SiC, standard (1.8%/4.5 lb.) additions of FeSiMg (0.039% residual Mg)
Pre-inoculated with SiC, reduced (1.6%/4.0 lb.) additions of FeSiMg (0.033% residual Mg)
Pre-inoculated with SiC, reduced (1.4%/ 3.5 lb.) additions of FeSiMg (0.029% residual Mg)
Figure 7. Chill tendency in thin wall ductile iron plates pre-inoculated with FeSi75 and SiC
as a ratio of the chill to the whole fracture area.
AFS Transactions 01-064 (Page 11 of 15)
0
100
200
300
400
500
600
700
800
900
1.5 m m 2 m m 3 m m
Plate thickness, m m
N
o
d
u
l
e
 
c
o
u
n
t
 
p
e
r
 
m
Pre-inoculated with FeSi75, standard (1.8% / 4.5 lb.) additions of FeSiM g (0.032% residual M g)
Pre-inoculated with SiC, standard (1.8% / 4.5 lb.) additions of FeSiM g (0.039% residual M g)
Pre-inoculated with SiC, reduced (1.6% / 4.0 lb.) additions of FeSiM g (0.033% residual M g)
Pre-inoculated with SiC, reduced (1.4% / 3.5 lb.) additions of FeSiM g (0.029% residual M g)
Figure 8. Average nodule count in thin wall ductile iron plates: C – in the center of a plate, E – in the edge of a plate.
 C
 E
 E
 C
 E
 C
 E
 C
AFS Transactions 01-064 (Page 12 of 15)
0
2
4
6
8
10
12
1.5 m m 2 m m 3 m m
Plate thickness, m m
A
r
e
a
 
o
f
 
g
r
a
p
h
i
t
Pre-inoculated with FeSi75, standard (1.8% / 4.5 lb.) additions of FeSiM g (0.032% residual M g)
Pre-inoculated with SiC, standard (1.8% / 4.5 lb.) additions of FeSiM g (0.039% residual M g)
Pre-inoculated with SiC, reduced (1.6% / 4.0 lb.) additions of FeSiM g (0.033% residual M g)
Pre-inoculated with SiC, reduced (1.4% / 3.5 lb.) additions of FeSiM g (0.029% residual M g)
Figure 9. Area of graphite in the center of thin wall ductile iron plates.
AFS Transactions 01-064 (Page 13 of 15)
0
10
20
30
40
50
60
70
Ir
o
n
 c
a
rb
id
e
s,
 %
Edge of plate pre-inoculated with FeSi75, standard (1.8%/4.5 lb.) additions of
FeSiMg (0.032% residual Mg)
Edge of plate pre-inoculated with SiC, standard (1.8%/4.5 lb.) additions of FeSiMg
(0.039% residual Mg)
Edge of plate pre-inoculated with SiC, reduced (1.6%/4.0 lb.) additions of FeSiMg
(0.033% residual Mg)
Edge of plate pre-inoculated with SiC, reduced (1.4%/ 3.5 lb.) additions of FeSiMg
(0.029% residual Mg)
Center of plate pre-inoculated with FeSi75, standard (1.8%/4.5 lb.) additions of
FeSiMg (0.032% residual Mg)
Center of plate pre-inoculated with SiC, standard (1.8%/4.5 lb.) additions of FeSiMg
(0.039% residual Mg)
Center of plate pre-inoculated with SiC, reduced (1.6%/ 4.0 lb.) additions of FeSiMg
(0.033% residual Mg)
Center of plate pre-inoculated with SiC, reduced (1.4%/ 3.5 lb.) additions of FeSiMg
(0.029% residual Mg)
Figure 10. Percentage of iron carbides in microstructure of 1-mm ductile iron plates
pre-inoculated with FeSi75 and SiC.
AFS Transactions 01-064 (Page 14 of 15)
0
5
10
15
20
25
30
1 1.5 2 3
Thickness of plates, mm
F
e
rr
ite
, 
%
Pre-inoculated with FeSi75, standard (1.8%/4.5 lb.) additions of FeSiMg (0.032% residual Mg)
Pre-inoculated with SiC, standard (1.8%/4.5 lb.) additions of FeSiMg (0.039% residual Mg)
Pre-inoculated with SiC, reduced (1.6%/4.0 lb.) additions of FeSiMg (0.033% residual Mg)
Pre-inoculated with SiC, reduced (1.4%/ 3.5 lb.) additions of FeSiMg (0.029% residual Mg)
Figure 11. Percentage of ferrite in microstructure of thin wall ductile iron plates pre-inoculated with FeSi75 and SiC.
AFS Transactions 01-064 (Page 15 of 15)
Based on the results of the study, pre-inoculation with SiC in production of thin wall ductile iron plates provides better
magnesium recovery, less chill tendency, and high castability, when residual magnesium content is at the same level as in
iron pre-inoculated with FeSi75.
SUMMARY AND CONCLUSIONS
The obtained resultsmay be summarized as follows:
1. Residual magnesium level and calculated magnesium recovery are much higher in those heats utilizing SiC as
furnace additions. With the same 4.5-lb (1.8%) FeSiMg-masteralloy additions, the SiC heats averaged 21% higher residual
magnesium (0.032% vs 0.039%). Those heats produced with SiC, but using reduced FeSiMg-masteralloy additions (1.6%
masteralloy) still resulted in higher residual magnesium then in heats using FeSi75 pre-inoculant and standard FeSiMg
masteralloy additions. The latest opens the possibility to reduce consumption of FeSiMg masteralloy.
2. Heats, pre-inoculated with SiC and treated with lower FeSiMg-masteralloy additions, showed high castability and
lowest percentage of iron carbides. Trial heats using SiC and standard FeSiMg-masteralloy additions exhibited the greatest
amount of iron carbides due to the considerably higher residual Mg levels. Thin wall ductile iron plates pre-inoculated with
SiC and treated with reduced addition of FeSiMg-masteralloy always showed the highest nodule count
3. These experiments confirmed previous works indicating the important role of residual magnesium on as-cast
structure and castability of ductile iron.
REFERENCES
1 T. Benecke, A. T. Ta, G. Kahr, W. D. Schubert, and B. Lux “Dissolution behavior and pre-inoculation effect of SiC in
gray cast iron melts” Elektroschemelzwerk Kempeten GmbH., Munchen, Germany (1987)
2. T. Benecke, S. Venkateswaran, W. D. Schubert, and B. Lux “The investigation of the influence of silicon carbide in
production of ductile iron” Elektroschemelzwerk Kempeten GmbH., Grefrath plan, Austria, (1993)
3. S. Venkateswaran, J. Wilfing, W. D. Schubert, B. Lux, and T. Benecke “Influence of SiC and FeSi75 additions on the
microstructure, cooling curve and shrinkage porosity of ductile iron” Paper presented at the Fourth International
Symposium on the Physical Metallurgy of Cast Iron, Tokyo (1989)
4. Y.S. Lerner, T. Frush, “Counter-Gravity Casting of Thin Wall Ductile Iron”, Proceedings of The Ductile Iron Society’s
1998 Keith D. Millis Symposium on Ductile Iron,SC, Hilton Head, pp.313-446. (1998)
5. Ductile iron. Molten metal. Processing American Foundrymen’s Society, Inc Des Plaines, Illinois USA (1986)
6. Ductile iron. Production. QIT – Fer et Titane Inc., Canada, pp 10-11. (1992)
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