The relationship between the variation of eutectic temperature and

The relationship between the variation of eutectic
temperature and melt quality in cast iron.
TOSHITAKE KANNO, HIROYOSHI KIMURA, HIDEO NAKAE
Kimura Foundry Co., Ltd.
1157 NAGASAWA, SHIMIZU-CHO, SUNTO-GUN, SHIZUOKA-KEN, 411-0905 JAPAN
Summary : Using a thermal analysis system consisting of three cups (Ⅰ: Inoculated, Ⅱ: Base melt, Ⅲ: tellurium
added), the effects of alloying elements on the graphite temperature(T EG, stable system eutectic temperature) and
the cementite eutectic temperature(T EC, meta-stable system eutectic temperature) of cast iron and the difference
between them(ΔT E) were investigated. This thermal analysis system was used to predict the chill depth and
mechanical properties.
The order of elements (graphitization elements) that expand ΔT E was found to be as follows: Si> Al>
C<2.9%> Cu> Co> P> Ni> C>2.9%. The order of elements (chilling elements) that narrow ΔT E was found to be as
follow: B> S>0.44%> V> Cr> S<0.44%> Mn> Nb> Ti> Sn> W> Mo> Sb. ΔT E has a relationship with the
distribution coefficient of the element in the interface between cementite and austenite. The chill depth of cast iron
can be determined by ΔT 1/ΔT E, in which ΔT 1 is the difference between supercooling turning point
temperature (T SC) and cementite eutectic temperature(T EC). The value of ΔT1/ΔT E shows where the eutectic
solidification curve lies between T EG(the eutectic temperature of non-chill melt) and T EC(the eutectic
temperature of complete chill melt). ΔT 1/ΔT E is a good indicator not only of the chill depth but also of graphite
types and tensile strength.
Key Words : thermal analysis, cast iron, cementite, graphite, eutectic temperature, alloying elements, graphite
types, chill depth, tensile strength
Zusamenfassung:
Der
Einfruss
der
Legierungselemennt
gegen
den
Gusseisenseutektische
Tempraturen(T EG:stabilisiertes eutektische Temperatur), Zementit Temperatur(TEC:metastailes eutektische
Temperatur) und beides Unterschied (△T E) war duruch dem drei Becher (Ⅰ: mit der Impfmittel, Ⅱ: keine
Zusatzmittel, Ⅲ : mit tellurium) nachforsht.Mit den Anwendung dieser drei Becher thermische Analyse
Methodes, wir versucht die Einstrahrungstief und die Festigkeitseigenschaften tu vorhersagen.
Die Ordununng der Elemennte die △T E zu verbreiten ist als folgennd: Si> Al> C<2.9%> Cu> Co> P> Ni>
C>2.9%. Die Ordununng der Elemennte die △T E zu verengen ist: B> S>0.44% > V> Cr> S<0.44% > Mn> Nb> Ti>
Sn> W> Mo> Sb. Wir fand dass die △T E kann bestimmt duruch dem Verteilunngs Koeffizient von jeden
Elemennte zwischen Zementit und Austenit sein. Die Gusseisen-Einstrahlungstief erzielt duruch die
Temperaturen-Rate △ T 1/ △ T E, die zeigt Temteraturen-Unterschied( △ T1) zwischen den
Unterkuelingsrueckschlag waerend der eutektische Erstarrung der geschmolzen Eisen und die
Zementit-eutektische Temperatur gegen △T E werden kann. Die △T1/△T E ist der Parameter das zeigt welches
Temperatur zwischen Graphit eutektische Temperatur(geschmolzen Eisen erstarrt mit keine Einstrahlung) und
Zementit eutektische Temperatur(geschmolzen Eisen erstarrt mit ganz Eisenstrahlung). Wir fand dass die Rate
△T 1/△T E hast nicht die Einstrahlungstief sondern die Graphitsgestalt und Zugfestigkeit.
Schluessel Woerter : thermische Analyse, Gusseisen, Zementit, Graphit, eutektische Temperatur,
Legierungselemennt, Verteilungskoeffizient, Graphitsgestalt, Einstrahlungstief, Zugfestigskeit.
Sommaire: En utilisant un système d'analyse thermique comprenant trois coupes (Ⅰ: Inoculée, Ⅱ: Base fondue,
Ⅲ: tellurium ajouté), nous avons étudié les effets des éléments d'alliage sur la température du graphite (T EG,
température eutectique à système stable) et la température eutectique de la cementite (T EC, température eutectique
à système meta-stable), ainsi que la différence entre ces deux (ΔT E) dans la fonte. Nous avons ainsi essayé de
prévoir la profondeur de trempe et les propriétés mécaniques en faisant appel à ce systme d'analyse thermique.
L'ordre des éléments (éléments de graphitisation) qui accroissent ΔT E est le suivant: Si> Al> C<2.9%> Cu> Co>
P> Ni> C>2.9%. L'ordre des éléments (éléments de trempe) qui réduisent ΔTE est le suivant: B> S>0.44%> V> Cr>
S<0.44% > Mn> Nb> Ti> Sn> W> Mo> Sb. ΔT E a une relation avec le coefficient de distribution des éléments
entre la cémentite et l'austénite. La profondeur de trempe de la fonte peut être déterrminée par ΔT1/ΔT E, où Δ
T 1 est la différence entre la température d'inversion supra-refroidissante (T SC) et la température eutectique de la
cémentite(T EC). ΔT1/ΔT E est le paramètre adimensionnel, c'est-à-dire où la solidification eutectique se produit
-1-
entre TEG(température eutectique de fusion sans trempe) et TEC(température eutectique de fusion à pleine
trempe). ΔT1/ΔT E présente une bonne relation non seulement avec la profondeur de trempe, mais aussi avec les
types de graphite et la résisitance à la rupture.
Mots-clés: analyse thermique, fonte, cémentite, graphite, température eutectique, éléments d'alliage, coeffieient de
distribution, types de graphite, température de trempe, résistance à la rupture.
1. Introduction
Many methods of predicting or judging the quality and mechanical properties of melt have been proposed.
Basically, these methods may be divided into three categories: by chill test[1-3], by cooling curve[4-10] and by
tensile strength[11-14]. However, the chill test method is unreliable because the chill depth changes according to
the pouring condition and in any case cannot be measured accurately. For the prediction by cooling curve,
although many tests and calculations have been reported, there is a lack of qualitative data. Assessment by tensile
strength is impractical because of the time required.
This paper reports an investigation into the effects of alloying elements on eutectic temperatures conducted by
means of a thermal analysis system consisting of three cups[15]: the first containing an inoculant, the second
containing nothing, the third containing tellurium. From the resultant cooling curves, the graphitization ability and
mechanical properties of various base melts were predicted.
2. Experimental method
Melting was done in a silica lined high frequency furnace of 60 kg, 3000 Hz. The basic composition was as
follows: 3.13mass% C (hereafter simply shown as %), 1.73% Si, 0.75% Mn, 0.07% P and 0.05% S. Each of which
was varied in turn. Other elements investigated were Cr, V, Cu, Ni, Co, Mo, W, Sb, Ti, Sn, Nb, Al, B. Adjustment
of composition was made using an electrode graphite and the following ferro-alloys: 75% Si, 73% Mn, 26% P,
50% S, 62% Cr, 65% Mo, 83% V, 72% Ti, 76% W, 19% B and 66% Nb. In addition, other substances having
purity of more than 99.5% were used, such as Cu, Ni, Co, Sn and Sb.
Fig. 1 shows the equipment used in this experiment and an example of temperature-time curves obtained. The
equipment consisted of three parts: three cups into which thermocouples had been inserted, a CPU that retrieved
and processed the variation of electromotive force from thermocouples, and a CRT that displayed the processed
data. Each cup consisted of a shell mold of 30 mm inner diameter and 50 mm height, and a Chromel-Alumel
thermocouple of 0.6mm diameter protected by silica tube. The weight of the melt poured into each cup was 250 ±
10 g.
3.0g of inoculant(Fe-37.59% Si-12.43% Ca-8.61% Ba) was put into the first cup before the melt was poured.
The inoculant mass corresponded to 1.2% of the melt and was enough to ensure complete graphitization of melt.
Therefore, it was possible to measure graphite eutectic temperature(ＴＥG). In order to measure the characteristics
of each specimen melt, the second cup contained no additive. 0.75g Te(99.99%) was put into the third cup before
the melt was poured. The Te mass corresponded to 0.3% of the melt and was enough to ensure complete chilling
of melt. Therefore, it was possible to measure cementite eutectic temperature(ＴＥＣ ).
Thermocouple
Quartz φ45
tube
φ30
Shell Mold
φ4
Ⅰ
30
80
50
Inoculant
Te
Ⅰ
Ⅱ
Ⅲ
Ⅱ
Ⅲ
CTR
Fig. 1 Schematic illustration of thermal analysis system.
(Ⅰ: Inoculated (3.0g), Ⅱ: Base melt, Ⅲ: Te added (0.75g))
-2-
Melt was held in the furnace at 1500℃ and the following tests were performed:
a.) Various melts were poured into the cup with the innoculant and into the cup with Te, and the effect of alloying
elements on the eutectic temperatures was investigated.
b.) Melts of varying C, Si and Cr content were inoculated and then poured into the three cups and into chill test
pieces(board chill, ASTM 3C type) at various time intervals following inoculation. By this means, the
relationship between eutectic temperature and the chill depth was investigated.
c.) Melts of varying C, Si and Cr content were inoculated and then poured into the three cups and into transverse
test bars(φ30×500mm). By this means, the mechanical properties were predicted.
3. Results and discussion
3.1 The effects of alloying elements on graphite and cementite eutectic temperature
Effects of C, Si, S and Cr on graphite and cementite eutectic temperature are shown in Fig. 2. For the melt of
1.7% Si, both TEG and TEC increase with increasing C content up to 2.9%, above which they become nearly
constant. According to equilibrium phase diagram of Fe-C binary system, both TEG and TEC do not change with
increasing C content beyond 2.1%. However, according to equilibrium phase diagram of Fe-C ternary system
reported by A.Boyles[16], both T EG and TEC increase with increasing C content even beyond 2.1%. As far as the
result of Boyles is concerned, the result is considered to be adequate. With increasing Si content, TEG increases
and TEC decreases markedly. This result is in a good agreement with the result of Oldfield[7].
In the case of S, as shown by arrow in figure, a transition point appears. That is, T EG increases with increasing S
content up to 0.2%, above which it decreases rapidly, hence ΔT E becomes narrower. This can be explained by
the formation of sulfide(MnS) and the effect of S on interfacial free energy between graphite and liquid[17]. TEG
decreases and TEC increases with increasing Cr. This result is consistent with Oldfield's experimental results[8].
35
TEG Si
Eutectic temp. ,
TEG Cr
Δ TE
TEC Cr
1120
TEC C
TEG S
ΔＴＥ(=Ｔ ＥＧ-ＴＥ Ｃ), K
TEG C
1140
TEC Si
0
2
Content , mass%
4
Fig.2 Effects of C, Si, S and Cr on Graphite
and Cementite eutectic temperature
Cu
Co
P
30
Sb
Ni
Mn
25
Nb
Mo・Sn・W
TEC S
1100
Al
Si
℃
1160
B
20
0.0
0.2
Cr
V
S
0.4
0.6
Content , mass%
0.8
1.0
Fig. 3 Effect of alloying elements on ΔT E.
Fig.3 shows the relationship between ΔT E and the contents of alloying elements (except for C) over the range
of 0 to 1.0%. As 1.7% Si is contained basically in every melt, ΔT E at 0% content become always 25℃ in any
alloying elements. As for Si, because 1.7% is base content, the range from 1.7% to 2.7% was evaluated.
According to this result, the order of elements that expend ΔT E per 1% content of element is as follow:
(1)
Si>Al>C<2.9%>Cu>Co>P>Ni>C>2.9%
The order of elements that narrow ΔT E per 1% content of element is as follow:
B>S>0.44%>V>Cr>S<0.44%>Mn>Nb>Ti>Sn>W>Mo>Sb
(2)
Table 1 shows variation of TEG, T EC and ΔT E per 1% content of alloying elements. The effect of alloying
elements on C activity reported by Neumann[18] and on distribution coefficient and ΔT E calculated by
Kagawa et al[19] are also shown. Here PXA/L, P SC/L and PXC/A mean the distribution coefficients between austenite
and molten iron, between cementite and molten iron, and between cementite and austenite, respectively.
-3-
Table1 Effect of various elements on graphite and cementite eutectic temperature and distribution coefficient.
Ele
me
nt
Present work
Ｔ EG,
Ｔ EC,
ΔＴＥ ,
K/mass% K/m ass% K/mass%
Si
Al
(C)
Cu
Co
P
Ni
C
Sb
Mo
Mn
W
Sn
Nb
S
Cr
V
(S)
B
4.7
13.9
10.2
2.7
1.8
-28.9
1.0
0.0
- 5.2
-17.7
- 4.0
- 6.1
- 9.3
- 3.7
-20.5
-10.5
-14.8
-50.0
-80.3
- 11.6
- 1.8
5.7
- 1.4
- 0.7
-31.1
- 1.1
0.0
- 5.1
-14.5
- 0.75
- 2.8
- 6.0
0.0
-10.3
5.9
3.3
-18.0
-26.0
16.3
15.7
4.5
4.1
2.5
2.2
2.1
0.0
- 0.1
- 3.2
- 3.25
- 3.3
- 3.3
- 3.7
-10.2
-16.4
-18.1
-32.0
-54.3
Calculated value 19）
Calculated
value18）
E.R.*
mass%
0.28-2.44
0-0.49
CE＜ 3.5
0.08-2.63
0-3.18
0.07-0.35
0.15-2.57
CE≧3.5
0-2.40
0.06-1.87
0.44-2.69
0.22-2.11
0-2.86
0.38-1.37
0.16-0.44
0.11-1.69
0-1.29
0.45-0.64
0-0.50
C activity
ΔC/X
+ 0.29
+ 0.215
+ 0.62
+ 0.075
+ 0.03
+ 0.345
+ 0.05
+ 0.62
+ 0.115
- 0.012
- 0.03
+ 0.0015
+ 0.10
- 0.14
+ 0.41
- 0.06
- 0.095
+ 0.41
+ 0.465
ＰＸＡ／Ｌ
ＰＸＣ ／Ｌ
ＰＸＣ ／Ａ
1.71
1.15
−
1.57
1.18
0.15
1.46
−
−
0.41
0.70
0.26
−
−
−
0.53
−
−
0.06
0.00
0.03
−
0.12
0.59
0.08
0.43
−
−
0.60
1.03
0.42
−
−
−
1.96
−
−
0.22
0.00
0.03
−
0.08
0.50
0.53
0.29
−
−
1.46
1.47
1.62
−
−
−
3.70
−
−
3.67
ΔＴＥ
K/m ass%
28.18
17.85
−
10.36
3.62
- 1.67
7.47
−
−
- 2.03
- 4.91
- 0.98
−
−
−
- 16.36
−
−
- 15.74
E.R.*: Experimental Range
Firstly, we focus our attention on the effect of alloying elements on carbon activity. Even though B, Sn, W, Sb,
S decrease carbon activity, ΔT E becomes narrower. And even though the effect of C on carbon activity is 0.62,
ΔT E does not vary with increasing C content above 2.9%, as shown in Fig.2. Therefore it is impossible to explain
the variation of ΔT E with the effect of alloying element on carbon activity.
Secondly, we focus our attention on the relationship between distribution coefficient of alloying elements and
eutectic temperature(T EG, T EC and ΔT E). In the interface between austenite and liquid, Si, Al, Cu are distributed
in austenite, because PXA/L of the elements is larger than 1. Therefore, they increase T EG. Meanwhile P, Mo and Cr
are distributed in the liquid, so TEG decreases. That is, if PXA/L is larger than 1, TEG increases and if PXA/L is
smaller than 1, TEG decreases. In the same way, if PXC/L is larger than 1, TEC increases and if PXC/L is smaller
than 1, TEC decreases. ΔT E is only the difference between T EG and T EC. Therefore, if the distribution coefficient
between austenite and cementite(P XC/A ) is larger than 1, ΔT E becomes wider. And if PXC/A is smaller than 1, Δ
T E becomes narrower.
From these results, it can be concluded that ΔT E is not related to carbon activity but to the distribution
coefficient of element in the interface between cementite and austenite, PXC/A .
3.2 Prediction of chill depth, using cooling curves
A schematic diagram of the cooling curves
obtained from the three cups is shown in Fig.4.
Here, ＴＥＧ refers to the plot of the retained
temperature obtained from the cup with
inoculant. Ｔ Ｅ Ｇ refers to the plot of the
retained temperature obtained from the cup with
Te. We call the supercooling turning point
temperature obtained from the cup without
additives as Ｔ Ｓ Ｃ , the highest eutectic
temperature as ＴEM and the difference between
them as ΔＴ, respectively.
Temperature
Inoculated
Base melt
TEG
ΔTE
TSC
ΔT1
TEC
Te added
Time
Fig.4 Schematic diagram of cooling curve
-4-
The relationship between ΔＴ１ and chill depth for C, Si and Cr content is shown in Fig.5. The relation between
the chill depth （D, mm) and ΔＴ１ is as follow:
Ｄ＝−０．６（ΔＴ１ ）＋２０
（３）
The correlation coefficient between them is low(r=0.89). Especially, for Si and Cr, there is considerable scatter.
The relationship between ΔT1/ΔTE and chill depth for C, Si and Cr content is shown in Fig.6. The relation
between the chill depth （D, mm) and ΔＴ１ is as follow:
Ｄ＝−２７（ΔT 1/ΔT E）＋２６
（４）
The correlation coefficient is high(r=0.98), so a good correlation is recognized.
30
30
20
D = -0.6×ΔＴ 1＋20
r=0.89
10
D = - 27×(ΔＴ1 /ΔＴ Ｅ )＋26
r = 0.98
Chill depth , mm
Chill depth , mm
C : 2.9∼3.5%
Si : 1.4∼2.4%
Cr : 0.1∼1.4%
20
10
C : 2.9∼3.5%
Si : 1.4∼2.4%
Cr : 0.1∼1.4%
0
10
20
ΔＴ 1 , K
0
0.0
30
Fig.5 Effect of ΔT 1 on chill depth
for C, Si and Cr contents.
0.2
0.4
0.6
Δ Ｔ1 /ΔＴ Ｅ
0.8
1.0
Fig.6 Effect of ΔT1/ΔT E on chill depth
for C, Si and Cr contents.
From the above results, there appears to be little correlation between ΔT 1 and chill depth, hence it is
impossible to predict chill depth correctly by only ΔT 1. The reason is thought to be due to the influence of
alloying element on ＴＥG, ＴＥC and ΔT E. As shown in Fig.2, ΔT E does not change when C contents increases
above 2.9%. On the other hand, as Si contents increases, ΔT E becomes wider, and as Cr contents increases, Δ
T E becomes narrower. Therefore, as ΔT E changes according to the melt composition, chill prediction by only Δ
T 1 is impossible.
The value of ΔT1/ΔT E shows where eutectic solidification occurred between TEG(the eutectic temperature)
and TEC(the eutectic temperature). In other words, from a practical viewpoint, the value of ΔT 1/ΔT E shows
whether eutectic solidification occurred nearer the best melt(non-chill melt) or the worst melt(complete chill
melt).ΔT1 can be regarded as the chilling tendency determined by melt composition and ΔT E can be regarded as
that determined by nucleation ability. For reference purposes, Fig.7 shows ΔT 1/ΔT E and graphite types obtained
from the transverse test bar.
100
Ratio of graphite types , %
E type
A type
80
60
40
D type
B
type
20
Chill
0
0.0
0.2
0.4
0.6
ΔＴ 1/ΔＴ Ｅ
0.8
1.0
Fig. 7 Relationship between ΔT1/ΔT E and ratio of graphite types.
-5-
3.3 Prediction of mechanical properties, using cooling curves
The relationship between ΔT 1/ΔT E and tensile strength is shown in Fig.8(C content is variable.) and Fig.9(Si
content is variable.). In both cases, tensile strength becomes higher with increasing ΔT 1/ΔT E , hence there
appears to be a good correlation between tensile strength and ΔT1/ΔTE. And in both cases, tensile strength
becomes lower with increasing content.
500
500
Tensile Strength, MPa
Tensile Strength, MPa
2.9% C
3.1% C
400
3.3% C
300
3.5% C
400
1.4% Si
300
1.7% Si
2.1% Si
2.4% Si
200
0.0
0.2
0.4
0.6
ΔＴ１／ΔＴＥ
0.8
200
0.0
1.0
0.2
0.4
0.6
0.8
1.0
ΔＴ１／ΔＴＥ
Fig.8 Relationship between ΔT 1/ΔT E and
tensile strength.
(Si:1.73%, Mn:0.75%, P:0.07%, S:0.05%)
Fig.9 Relationship between ΔT 1/ΔT E and
tensile strength.
(C:3.13%, Mn:0.75%, P:0.07%, S:0.05%)
The relationship between tensile strength, carbon equivalent and ΔT1/ΔT E is shown in Fig.10. The
relationship between them is as follow:
(5)
σｔ = {180×(ΔT1/ΔT E)+ 170}×(4.4 - CE)+ 160
The correlation coefficient is high(r=0.95), so a good correlation is recognized. For reference purposes, the
degree of normality which is suggested by Patterson[12] is also shown. The degree of normality is calculated as
follow: RG =σｔ ×100 /σｔｎ ＝σｔ ×100 /(102−82.5Sc) Here, σｔ is actual tensile strength and σｔｎ is
standard tensile strength. Our experimental result is in a good agreement with the data of Patterson. Therefore, it
is concluded that ΔT1 /ΔTE is a good value for the prediction of material quality.
500
Tensile Strength , MPa
ΔＴ1 /ΔＴＥ
=1.0
400
200
3.4
C :3.1%
C :3.5%
Si:1.7%
Si:2.4%
0.8
0.6
0.4
300
C :2.9%
C :3.3%
Si:1.4%
Si:2.1%
RG=120%
0.2
0.0
RG=100%
3.6
3.8
4.0
4.2
4.4
Carbon equivalent（CE=C+Si/3）, %
Fig.10 Relationship between CE and tensile strength.
The degree of normality of Patterson is determined by tensile strength. However, tensile strength is affected not
only by ΔT 1/ΔT E, but also by matrix. Provided that cooling rate is constant, the matrix of cast iron is determined
mainly by chemical composition and not by material quality. Therefore, since predictions based on tensile
-6-
strength do not take the matrix into account, errors easily occur. On the other hand, as ΔT1/ΔT E is determined
by eutectic temperatures and has no relationship with matrix, it is a good value for predicting the quality of cast
iron. Furthermore, it may be used to judge the material quality, regardless of the variation of contents and
elements.
From these above results, it is concluded that ΔT 1/ΔT E obtained from the three cups thermal analysis system
(We call it graphitization ability) is an efficient value of controlling melt quality before casting.
4. Conclusion
Using a thermal analysis system consisting of three cups (First: Inoculated, Second: Base melt, Third: tellurium
added), the relationship between thermal analysis curves and the chill depth and mechanical properties is
investigated. The results are as follows:
(1) The order of elements that expend ΔT E per 1% content of element is as follow:
Si>Al>C<2.9%>Cu>Co>P>Ni>C>2.9%
The order of elements that narrow ΔT E per 1% content of element is as follow:
B>S>0.44%>V>Cr>S<0.44%>Mn>Nb>Ti>Sn>W>Mo>Sb
(2) The difference between graphite and cementite eutectic temperature, ΔT E, is determined by the distribution
coefficient in the interface between cementite and austenite.
(3)The chill depth of cast iron melt is determined by ΔT1/ΔT E．
(4)There is a good relationship between ΔＴ１ /ΔＴＥ and tensile strength.
(5)ΔＴ１ /ΔＴＥ（graphitization ability）obtained from the three cups thermal analysis system is a good value of
predicting melt quality, even before casting.
References
１）Kohei Taniguchi: Tetsu to Hagane (Japan), 18(1932) 952
２）Edited by Cast Iron Melting Department of Japan：J. Foundry Engineering Society of Japan, 41(1969)71
３）S.Okada, Y.Maehashi, S.Wakamatsu, Y.Ishida:J. Foundry Engineering Society of Japan,44(1972)107
４）K. Abe：J. The Materials Process Technology of Japan, 16(1975)25
５）R.W.Heine, C.R.Loper,Jr. and M.O.Chaudhari:AFS Transaction, 79(1971)389
６）E.F.Ryntz, Jr., J.F.Janowak, A.W.Hochstein and C.A.Wargel:AFS Transaction, 79(1971)79
7）W.Oldfield:B.C.I.R.A.Journal, (1962)17
8）W.Oldfield:B.C.I.R.A.Journal, (1962)506
9）K. Kishitake, T. Owadano, K. Miyamoto：J. Foundry Engineering Society of Japan, 53(1981)295
10）K. Nakamura：J. The Materials Process Technology of Japan, 27(1986)26
11) P.A. Heller, H.Jungbluth: Giesserei, 42(1955)255
12) W. Patterson: Giesserei, 46(1959)289
13) N. Kayama, K. Abe, Y. Masaki: J. Foundry Engineering Society of Japan ,(1962)169
14) Edited by Foundry Engineering Society of Japan: Casting Handbook, Maruzen Publishing,(1986)514
15) T.Kanno, Y.You, H.Hiraoka, M.Morinaka and H.Nakae: Proceedings of AFC-5,(1997)137
16）A.Boyles:The structure of cast iron,Ame Soc. of Metals,(1946)2
17）H. Nakae and T. Yamauchi: J. Institute of Metals of Japan , 58(1994) 30
18）F.Neumann,H.Schenck,W.Patterson:Giesserei,47(1960)25
19）A. Kagawa, T. Okamoto: J. Foundry Engineering Society of Japan , 57(1985) 113
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