I. MIHALIC POKOPEC et al.: INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
59–65
INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
VPLIV CHUNKY GRAFITA NA LATENTNO TOPLOTO
Ivana Mihalic Pokopec1, Primo` Mrvar2, Branko Bauer1
1University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Ivana Lucica 5, 10002 Zagreb, Croatia
2University of Ljubljana, Faculty of Natural Science and Engineering, Lepi pot 1, 1000 Ljubljana, Slovenia
branko.bauer@fsb.hr
Prejem rokopisa – received: 2017-07-21; sprejem za objavo – accepted for publication: 2017-10-02
doi:10.17222/mit.2017.122
The study presents the results of investigations of the thermal effects that take place during the heating and cooling of samples
of the spheroidal graphite cast iron with different amounts of chunky graphite (CHG) in the microstructure. In order to obtain a
different amount of CHG, cone blocks  300 mm × 350 mm were casted. Two different test melts, EN-GJS-400-18 with 0.7 %
of the mass fraction of Ni and EN-GJS-400-15 with 3.5 % of the mass fraction of Si were used. From each block three samples,
with different cooling rates, were prepared. For studies of phase transformations, the technique of differential scanning
calorimetry (DSC) was used. The microstructure was examined before and after DSC by optical microscopy. The obtained
values of the enthalpy of melting and solidification differ and depend on the initial microstructure of the examined samples. The
remelting of samples results in magnesium oxidation and significant changes in the eutectic morphology, which, at room
temperature, consists of fine and/or coarse undercooled types of graphite with a lamellar morphology.
Keywords: chunky graphite, DSC, graphite morphology, heating and cooling
Raziskava predstavlja rezultate toplotnih efektov med segrevanjem in hlajenjem vzorcev iz sive litine s kroglastim grafitom z
razli~nimi dele`i chunky grafita (CHG). Z namenom pridobitve razli~nih dele`ev chunky grafita, so bili vliti ulitki sto`~aste
oblike z zgornjim premerom 300 mm in vi{ino 350 mm. Uporabljeni sta bili dve razli~ni talini, EN-GJS-400-18, z 0,7 masnega
% Ni in EN-GJS-400-15, s 3,5 masnimi % Si. Iz vsakega bloka so bili pripravljeni trije vzorci z razli~nimi ohlajevalnimi
hitrostmi. Za raziskave faznih transformacij je bila uporabljena diferen~na vrsti~na kalorimetrija (DSC). Vzorci so bili preiskani
z opti~no metalografijo pred in po DSC analizi. Izmerjene vrednosti entalpij taljenja in strjevanja se razlikujejo in so odvisne od
mikrostrukture preiskanih vzorcev. Posledica pretaljevanja vzorcev je oksidacija magnezija in posledi~no spremembe v
morfologiji evtektika, ki pri sobni temperaturi vsebuje fine in/ali grobe oblike podhlajenega lamelnega grafita.
Klju~ne besede: chunky grafit, DSC, morfolgija grafita, segrevanje in ohlajanje
1 INTRODUCTION
The manufacture of thick-walled castings of sphe-
roidal graphite cast iron represents an area of continuing
growth, and this trend is set to continue at least over the
next 20 years. This refers primarily to the manufacture of
castings for wind farms, manufacture of containers for
the permanent storage of nuclear waste and the industry
for heavy-duty vehicles.1–6 Future applications of thick-
walled castings of spheroidal graphite cast irons will
require increasingly thicker walls. In parallel, the re-
quirements for mechanical properties will grow too, thus
leading to a growing importance of the high-quality
spheroidal morphology of the graphite. Every dege-
neration of graphite, which is a frequent and undesirable
phenomenon in the manufacture of thick-walled castings,
leads to a decrease of the mechanical properties and very
often results in the discarding of such castings.7 The
most detrimental among these deteriorations is chunky
graphite. This defect mainly occurs in the thermal centre
of the thick-walled cast parts and causes a decrease in
the mechanical properties, especially tensile strength,
elongation and fatigue strength.3–10
The main causes for the occurrence of CHG are slow
cooling rate and chemical composition. The slower the
cooling rate, the greater, the fewer and more irregular the
nodules. These conditions favour the formation of CHG.
As for the chemical composition, numerous studies have
established that Ce, Si, Ni and Ca promote the formation
of chunky graphite.1,3,5,6,9
It is well-known that chunky graphite forms during a
eutectic reaction. However, there is a disagreement about
whether chunky graphite forms in the melt during the
early phase of eutectic solidification or on locations of
the remaining melt towards the end of the eutectic solidi-
fication. Likewise, it is not known whether the sphero-
idal or chunky graphite forms first.
According to H. Itofuji and H. Uchikava11 the for-
mation and growth of chunky graphite occurs in the later
phase of eutectic solidification, when the growth of the
nodule is almost in its final phase. The formation of
chunky graphite in the later phase of eutectic solidifica-
tion is in line with H. Nakae et al.12 According to Z.
Zhang et al.13 chunky graphite forms in the middle or
towards the end of eutectic solidification at the auste-
nite/liquid interface and continues to grow towards the
rest of the melt. On the other hand, according to J.
Zhou,14,15 chunky graphite forms in the initial phase of
eutectic solidification.
Materiali in tehnologije / Materials and technology 52 (2018) 1, 59–65 59
UDK 620.1/.2:669.131.6:621.78.08 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 52(1)59(2018)
The DSC method enables us to follow the phase
transformations during the heating and cooling of sam-
ples and the enthalpies with reference to reactions during
melting and solidification and transformation in the solid
state.16,17 In this paper, the DSC method was used to
determine the characteristic temperatures and enthalpies
during heating and cooling. By using samples with a
different share of CHG, an attempt was made to identify
a relation to solidification enthalpy and the influence of
CHG content on newly formed microstructure. In order
to analyse more easily and precisely the DSC cooling
curves of samples, a metallographic analysis was per-
formed before and after the analysis by an optical micro-
scope.
2 EXPERIMENTAL PROCEDURE
Two different test melts were used: EN-GJS-400-18
with 0.7 % of the mass fraction of Ni and EN-GJS-
400-15 with 3.5 % of the mass fraction of Si.
The test castings used in this study were cone blocks
with diameter of 300 mm and a height of 350 mm, Fig-
ure 1, to enable investigation of the influence of different
cooling rates on chunky-graphite formation.
Two moulds (M1, M2) were produced from sodium
silicate bonded sand. For both moulds, KALPUR direct
pouring process was used.
Both test melts were produced in a 5.6 t capacity
medium frequency induction furnace. The charge mate-
rial consisted of grey pig iron (Sorelmetal®), steel scrap
and returns as listed in Table 1. In order to increase
carbon and silicon contents and the nucleation ability of
the melt, SiC (~92 % of the mass fraction of SiC) was
added into the furnace with the metallic charge. Also, for
increasing Si content, in the second melt 2.3 % of the
mass fraction of FeSi was added. Once melting was
finished, the chemical composition of the metal was
adjusted according to carbon and silicon evaluation given
by thermal analysis and spectrometric analysis on the
coupon for the other elements.
For both moulds, the spheroidising treatment was
carried out in a dedicated ladle of 200 kg capacity by
adding ~ 1.8 % of the mass fraction of FeSiMg alloy
(44–48 % of the mass fraction of Si, 3.5–3.8 % of the
mass fraction of Mg, 0.9–1.1 % of the mass fraction of
Ca, 0.5–1.2 % of the mass fraction of Al, 0.6–0.8 % of
the mass fraction of RE, Fe bal.) and 0.2 % of the mass
fraction of cover alloy (46–50 % of the mass fraction of
Si, 1.8–2.2 % of the mass fraction of Ba, 0.4-0.6 % of
the mass fraction of Ca, 0.5–1.0 % of the mass fraction
of Al, Fe bal.) using the sandwich method at ~1480 °C.
The FeSiMg alloy was positioned at the bottom of the
casting ladle and then covered by cover alloy before
pouring the iron from the furnace. In first casting ladle
0.7 % of the mass fraction of Ni and in the second
casting ladle 0.7 % of the mass fraction of FeSi was
added on the bottom before pouring the iron from the
furnace.
After the treatment, slag was removed from the melt
surface and the melt was poured into the mould. Holding
time was ~3 min. Second inoculation (in-stream) during
pouring in the mould was performed by adding 0.45 %
of the mass fraction of inoculant containing Ce (70–76 %
of the mass fraction of Si, 1.5–2.0 % of the mass fraction
of Ce, 0.75–1.25 % of the mass fraction of Al, > 1 % of
the mass fraction of O and S, Fe bal.). Pouring tem-
perature for both moulds was 1380 °C and pouring time
27 s.
Just before pouring the melt in the mould, the chilled
coupon was analysed by optical emission spectrometer
(ARL 3460). C and Si contents were determined from
the results of thermal analysis using the ATAS® system.
Chemical composition is listed in Table 2.
Each cylindrical block was afterwards sectioned
along the vertical symmetry plane to evaluate the zone
affected by CHG, and then one half of each block was
sectioned along the horizontal symmetry plane 50 mm
from the base of the cone. From the bottom part of the
sectioned cone, the slice of 10 mm thickness was then
taken for sample preparation.
I. MIHALIC POKOPEC et al.: INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
60 Materiali in tehnologije / Materials and technology 52 (2018) 1, 59–65
Figure 1: Pattern used in experiment
Table 1: Charge materials used for melting, in mass fractions
Total
Sorel-
metal®
(w/%)
Returns
(w/%)
Steel
scrap
(w/%)
SiC
(w/%)
FeSi
(w/%)
5.6 t 70 21 9 0.1 0.2*
*2,3 (w/%) for 2nd melt
Table 2: Chemical composition of the melts
Cone
No.
In mass fractions, (w/%)
C Si Mn S P Mg Co Ni Cr Cu Sn Mo Ti Al ACEL*
1 3.25 1.75 0.160 0.011 0.032 0.036 0.017 0.720 0.030 0.016 0.004 0.003 0.007 0.0095 4.17
2 2.91 3.46 0.162 0.006 0.034 0.059 0.016 0.026 0.030 0.016 0.006 0.003 0.011 0.0247 4.24
For DSC, three samples with three different cooling
rates (from the edge to the centre) from each slice were
prepared, Figure 2. Cooling rates were: 0.036, 0.022 and
0.016 °C/s. The sampling locations were determined by
simulation of the casting and solidification processes.
Samples were  5 mm × 4 mm in size. Samples of cone
1 were marked as 1-D1, 2-D2 and 3-D3, and of cone 2 as
2-D1, 2-D2 and 2-D3.
Differential scanning calorimetry or DSC with ther-
mogravimetry was carried out using a simultaneous
thermal analyser NETZSCH STA 449 F3 Jupiter® at a
cooling/heating rate of 10 K/min, Figure 3. Holding
temperature was 1400 °C and holding time 1 minute.
The metallographic analysis was done by optical
microscope (Olympus BX 61) which was equipped with
a system for automatic image processing (Analysis®
Materials Research Lab). The samples were etched in a
3 % nital solution. Metallographic analysis was carried
out on the same samples for DSC, before and after the
calorimetric measurements.
3 RESULTS
DSC cooling and heating diagrams of sample 1-D1
taken from cone 1 for the maximum cooling rate are
shown in Figure 4. The microstructures before and after
the conducted DSC analysis for the said sample are
shown in Figure 5. Table 3 shows the results of melting
and solidification enthalpies and temperatures measured
on all samples of cone 1.
Table 3: Significant temperatures and enthalpies for cone 1, with
0.7 % of the mass fraction of Ni
Parameter
Sample
1-D1 1-D2 1-D3
Heating
TCurie, °C 693 693.1 690.1
TP
, °C 780.1 781.7 780.9
TF+G
, °C 801.7 806.8 804.6
TS, °C 1115.2 1117.1 1118.2
TE, °C 1153.5 1138.5 1145
Hmelt., J/g 116.1 111.9 113.2
Cooling
TL, °C 1177.5 1169.5 1167.8
TE, °C 1149.6 1146.2 1144.1
TE’, °C 1136.4 1134.8 1125.2
Teutektoid, °C 708.6 733.1 733
Hsolidif., J/g 124.6 99.4 80.3
The heating curve shown in Figure 4 indicates that
the sequence of phase transformation and melting is as
follows; at 693 °C the Curie temperature is recorded,
followed by eutectoid transformation, where at 780.1 °C
pearlite (
+Fe3C) first starts to transform into austenite,
and then at 801.7 °C the eutectoid transformation
according stable phase diagram (Fe-C(Graphite)-Si),
whereby the ferrite and eutectoid graphite, present on the
existing graphitic particles, transform into austenite. The
heating of austenite and graphite follows, whereby part
of the secondary graphite dissolves in austenite (diffu-
sion of carbon from graphite nodules into austenite). The
solidus temperature is defined at 1115.2 °C. Considering
the thermodynamic phase calculation in Thermo-Calc for
I. MIHALIC POKOPEC et al.: INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
Materiali in tehnologije / Materials and technology 52 (2018) 1, 59–65 61
Figure 4: DSC curve: a) heating and b) cooling of sample 1-D1Figure 3: Heating and cooling regime during DSC analysis
Figure 2: Schematic diagram of sampling for DSC analysis
the given composition at this temperature, the eutectic
begins to melt 
+MgX (X=Si and/or S). The melting of
this eutectic ends at 1153.5 °C, followed by the melting
of graphite eutectic (
+G) and melting of primary auste-
nite crystals at the end. Thereafter everything assumes a
liquid form and the heating of the melt starts.
Figure 4b shows the cooling curve for the same
sample. From the cooling curve, it is first noticed the
cooling of the melt. At 1177.5 °C, the liquidus tempe-
rature (TL) is recorded. At this temperature starts the
crystallisation of primary austenite crystals and ends at
1149.5 °C. At 1136.4 °C the remaining melt solidifies
into austenite and graphite. During eutectic solidifica-
tion, 124.1 J/g of latent heat is released. It is visible from
the figure showing the corresponding microstructure
(Figure 5b)) that the composition of the alloy is slightly
hypoeutectic which is proved by the dendrite-shaped
austenite regions. The eutectic morphology changes
significantly after remelting. It is observed that the resi-
dual magnesium oxidation causes the formation of an
undercooled form of graphite which has largely a
lamellar morphology. The magnesium oxidation occurs
I. MIHALIC POKOPEC et al.: INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
62 Materiali in tehnologije / Materials and technology 52 (2018) 1, 59–65
Figure 7: Microstructure: a) before and b) after DSC analysis of sample 1-D3
Figure 6: Microstructure: a) before and b) after DSC analysis of sample 1-D2
Figure 5: Microstructure: a) before and b) after DSC analysis of sample 1-D1
despite the inert atmosphere of argon in the DSC testing
device. At the end of solidification the cooling of the
microstructure follows, which consists of primary auste-
nite and eutectic (
+G). It is interesting to note that the
second eutectic (MgX+
) recorded on the heating curve
was not recorded during the cooling of the same sample,
which proves that the MgSi decomposed in Mg which
oxidized and in Si which remained in the melt. At 708.6
°C starts the eutectoid transformation of both austenites
(primary and eutectic) into ferrite and graphite and/or
pearlite.
The heating and cooling curves of samples 1-D2 and
1-D3 are characterised by the existence of the same cha-
racteristic temperatures, which means that the sequence
of phase transformations and melting/solidification of
single phases is the same. Images of microstructure
before and after testing are shown in Figures 6 and 7.
The results of the DSC analysis of samples of cone 2
are shown in Table 4. Beside the DSC analysis results,
the images of microstructure in the initial phase and after
testing are also shown, Figures 8 to 10.
By analysing the heating and cooling curves of cone
2 samples, it has been observed that samples undergo the
same phase transformations and melting/solidification
sequence as the samples of cone 1. The main difference
to the samples of cone 1 is that the eutectoid transfor-
mation temperatures are shifted towards higher values as
a result of high content of Si in cone 2. Likewise, the
transformation peaks of pearlite and ferrite in austenite
on the heating curve are less noticeable. As a matter of
fact, these two peaks often overlap.17 This is why it is
difficult to establish the exact temperature at the end of
eutectic transformation of pearlite in austenite and at the
beginning of the transformation of ferrite into graphite
and austenite. During heating, also in cone 2, the exis-
I. MIHALIC POKOPEC et al.: INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
Materiali in tehnologije / Materials and technology 52 (2018) 1, 59–65 63
Figure 9: Microstructure: a) before and b) after DSC analysis of sample 2-D2
Figure 8: Microstructure: a) before and b) after DSC analysis of sample 2-D1
Table 4: Significant temperatures and enthalpies for cone 2, with
3.5 % of the mass fractions of Si
Parameter
Sample
2-D1 2-D2 2-D3
Heating
TCurie, °C 711.3 712.7 710.4
TP
, °C 851.5 853.3 853.7
TF+G
, °C
TS, °C 1127.1 1126.9 1127.3
TE, °C 1148.7 1148.2 1144.6
Hmelt., J/g 109 107 125.4
Cooling
TL, °C 1179 1167.5 1169.6
TE, °C 1150.4 1148.2 1152.7
TE‘, °C 1131.8 1129.7 1131.7
Teutectoid, °C 801.4 802.3 797.3
Hsolidif., J/g 122 89.6 132.2
tence of the second eutectic has been noticed, which was
absent during re-cooling.
4 DISCUSSION
From the heating results with reference to samples of
cone 1, it is visible that melting enthalpy differs slightly
among samples with different cooling rates, Table 3. By
comparing the cooling results for the same cone, it
emerges that reference solidification temperatures shift
towards lower values as the cooling rate decreases from
the edge towards the centre. The latent heat released
during solidification decreases significantly.
By examining the images of microstructure before
the DSC analysis, it can be clearly observed that the con-
tent of chunky graphite in cone 1 with 0.7 % of the mass
fraction of Ni increases from the edge towards the
centre. So the sample 1-D3, Figure 7a, shows practically
a 100 % of eutectic graphite with chunky graphite mor-
phology, whereas the sample 1-D1, Figure 5a, has a
microstructure of regular spheroidal graphite cast iron. In
addition, different microstructures were obtained after
the conducted DSC analysis. Microstructure consists of a
primary dendritic austenite and a undercooled form of
graphite with a certain content of irregularly distributed
graphite accumulations. The undercooled graphite exhi-
bits a coarse morphology in sample 1-D1, a mixed mor-
phology (finer more than coarser undercooled graphite)
in sample 1-D2, and the finest morphology in sample
1-D3. The finer the undercooled graphite, the smaller the
graphite accumulations, Figures 5 to 7b.
The difference in the microstructure of samples
before and after DSC analysis occurs as a result of
magnesium oxidation during reheating, which caused the
absence of conditions for formation of the spheroidal
graphite and the growth of graphite in the form of
lamellar graphite in the undercooled form. The content
of residual magnesium decreased to approximately
0.01 %.18
Based on the results of DSC analysis and analysis of
metallographic images of samples it can be concluded
that the lower the enthalpy during solidification, the finer
the undercooled graphite. In the sample 1-D3 with the
finest morphology of undercooled graphite, the value of
solidification enthalpy amounts to 80.3 J/g, in the sample
1-D2 it amounts to 99.4 J/g, and in the sample 1-D1 to
124.6 J/g (spheroidal graphite before the analysis, that is,
the coarsest graphite after the analysis). The same con-
clusion is valid for characteristic solidification tempera-
tures. Table 3 shows also the temperature at the beginn-
ing of the eutectoid transformation Teutectoid. In the sample
1-D1 with the lowest temperature Teutectoid = 708.6 °C, the
lamellar morphology eutectic with the coarsest shape
could be observed, Figure 5 b) (diffusion paths of carbon
transport from austenite to graphitic particles are more
distant compared to samples 1-D2 and 1-D3).
By comparing the heating results for samples of cone
2, Table 4, it can be seen that there is not much diffe-
rence between the characteristic temperatures and melt-
ing enthalpy with reference to samples 2-D1 and 2-D2.
The sample 2-D3 with respect to samples 2-D1 and 2-D2
has a significantly lower value of TE and a higher value
of melting enthalpy.
I. MIHALIC POKOPEC et al.: INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
64 Materiali in tehnologije / Materials and technology 52 (2018) 1, 59–65
Figure 11: Comparison of enthalpies of melting and solidification of
samples from cones 1 and 2
Figure 10: Microstructure: a) before and b) after DSC analysis of sample 2-D3
By examining the microstructure images before the
DSC analysis, it could be clearly observed that the con-
tent of chunky graphite in cone 2 with 3.5 % of the mass
fraction of Si does not increase from the edge towards
the centre, but rather the opposite. In samples 2-D1 and
2-D2, before the conducted testing, the graphite eutectic
has an equal share of spheroidal and chunky morpho-
logy, Figures 8a and 9a. In the sample 2-D3, before
testing, graphite eutectic with spheroidal morphology
prevails, whereas chunky graphite is present with a
rather low share, Figure 10a, therefore the melting en-
thalpy differ compared to samples 2-D1 and 2-D2. TE is
lower for approximately 4 °C, whereas Hmelt. is signifi-
cantly higher, for approximately 16 J/g, as shown in
Table 4.
By analysing the microstructure images it can be
concluded that the microstructure of samples after
cooling consists of primary austenite dendrites and gra-
phite eutectic with morphology of undercooled lamellar
graphite, Figures 8 to 10b, as in cone 1. It is a slightly
hypoeutectic alloy. The greater the presence of chunky
graphite in the microstructure before the DSC analysis,
the finer the undercooled graphite. In sample 2-D3,
before testing, spheroidal graphite prevails, therefore
after testing, the undercooled graphite is the coarsest.
The comparison of heating and cooling enthalpies for
samples in both cones is shown in Figure 11. The values
of enthalpies as well as the final microstructure hugely
depend on the initial microstructure. The influence of the
quantity of graphite eutectic with spheroidal morphology
in the initial microstructure on melting and solidification
enthalpies is observed. After melting and solidification
of initial microstructure samples with greater content of
graphite eutectic with spheroidal morphology a final
microstructure with coarser undercooled graphite prima-
rily of lamellar morphology is formed. As a conse-
quence, and according to results obtained by testing
samples of both cones, it follows that the solidification
enthalpy at this microstructure is greater too. The diffe-
rences in solidification enthalpy values are more pro-
nounced compared to differences in melting enthalpy, in
respect of changes in the graphite morphology.
5 CONCLUSION
Based on the results obtained in this study, the
following main conclusions can be drawn:
• the obtained values of the melting and solidification
enthalpy differ and depend on the initial micro-
structure of the samples.
• the higher the content of graphite eutectic with a
spheroidal morphology before the DSC analysis, the
greater the solidification enthalpy. Such a micro-
structure results after remelting in the formation of a
coarser undercooled graphite of primarily lamellar
morphology.
• the higher the content of chunky graphite or small
graphite particles of irregular shape before remelting
the lower the solidification enthalpy and the finer the
undercooled graphite.
Acknowledgements
This work is partially supported by the foundry MIV
d.d. Vara`din.
6 REFERENCES
1 H. Löblich, Effect of nucleation conditions on the development of
chunky graphite in heavy ductile iron castings, Giessereiforschung
58 (2006) 3, 28–41
2 O. Knustad, L. Magnusson Åberg, Chunky Graphite, Effects and
theories on formation and prevention, 14th Inter. Foundry Confe-
rence, Opatija, Croatia, 2014
3 R. Källbom, K. Hamberg, M. Wessen, L.-E. Björkegren, On the
solidification sequence of ductile iron castings containing chunky
graphite, Materials Science and Engineering A, 413-414 (2005),
346–351, doi:10.1016/j.msea.2005.08.210
4 J. Lacaze, L. Magnusson, J. Sertucha, Review of microstructural
features of chunky graphite in ductile cast irons, 2013 Keith Millis
Symp. on Ductile Cast Iron, Nashville, USA, 2013, 360–368
5 P. Ferro, A. Fabrizi, R. Cervo, C. Carollo: Effect of inoculant con-
taining rare earth metals and bismuth on microstructure and
mechanical properties of heavy-section near-eutectic ductile iron
castings, Journal of Materials Processing Technology, 213 (2013),
1601–1608, doi:10.1016/j.jmatprotec.2013.03.012
6 K. Hartung, O. Knustad, K. Wardenaer, Chunky graphite in ductile
cast iron castings- Theories and examples, Indian Foundry Journal,
55 (2009), 25–29, doi:10.3969/j.issn.1003-8345.2009.02.010
7 R. Källbom, K. Hamberg, L. E. Björkegren: Chunky Graphite – For-
mation and Influence on Mechanical Properties in Ductile Cast Iron,
Proc. of the Gjutdesign 2005, Espoo, Finland, 2005
8 M. Koch: Chunky Graphite; Effects and theories on formation and
prevention, 2013 Keith Millis Symp. on Ductile Cast iron, Nashville,
SAD, 2013, doi:10.1007/s11661-008-9731-y
9 J. Riposan, M. Chisamera, S. Stan: Performance of heavy ductile
iron castings for windmills, China Foundry, 7(2010) 2, 163–170
10 M. Gagné, C. Labrecque: Microstrustural Defects in heavy section
ductile iron castings: formation and effect on properties, AFS Tran-
sactions, 117 (2009), 561–571
11 H. Itofuji, H. Uchikava: Formation Mechanism of Chunky Graphite
in Heavy-section Ductile Cast Irons, AFS Transactions 90 (1990) 42,
429–448
12 H. Nakae, S. Jung, H.-C. Shin: Formation mechanism of chunky
graphite and its preventive measures, Journal of Materials Science &
Technology, 24 (2008), 289–295
13 Z. Zhang, H.M. Flower, Y. Niu: Classification of degenerate graphite
and its formation processes in heavy section ductile iron, Materials
Science and Technology, 5 (1989), 657–664
14 J. Zhou: Colour Metallography of Cast Iron – Spheroidal Graphite
Cast Iron- Part III, China Foundry, 7 (2010) 1, 292–307
15 J. Zhou, W. Schmitz, S. Engler. Untersuchung der Gefügebildung
von Gußeisen mit Kugelgraphit bei langsamer Erstarrung,
Giesserei-Forschung, 39 (1987) 2, 55–70
16 R. Przeliorz, J. Pi¹tkowski: Investigation of phase transformations in
ductile cast iron of differential scanning calorimetry, Materials
Science and Engineering, 22 (2011), 1–9
17 F. Binczyk, A. Tomaszewska, A. Smoliñski: Calorimetric analysis of
heating and cooling process of nodular cast iron, Archives of
Foundry Engineering, 7 (2007) 1, 25–30
18 P. Mrvar, M. Trbi`an, J. Medved: Investigation of cast iron solidi-
fication with dilatation analysis, KZT 33 (1999) 1–2, 45–49
I. MIHALIC POKOPEC et al.: INFLUENCE OF CHUNKY GRAPHITE ON LATENT HEAT
Materiali in tehnologije / Materials and technology 52 (2018) 1, 59–65 65