Bramat 2015 Edi [609201]

Nr.
crt.Heat Ladle InoculantChemical composition, [wt.%]
Ca Al La Zr Si Ba
1.H. IL1 BaCaAlFeSi 1.202 1.078 – – 72.7 1.25
2. L2 LaCaAlFeSi 1.198 0.961 4.0 0.0048 67.0 –
3. H. II L3 Uninoculated – – – – – –
Chemical elementsBaseIron
after
holdingHeat I Heat II
Pouring Ladle
L.1 L.2 L.3Chemical composition, [wt. %]
Base
ElementsC 3.65 3.58 3.55 3.55
Si 1.44 1.81 1.77 1.42
Mn 0.428 0.418 0.425 0.42
P 0.021 0.02 0.021 0.021
S 0.028 0.026 0.027 0.026Rezidual ElementsCr 0.043 0.043 0.043 0.042
Ni 0.032 0.032 0.036 0.033
Mo 0.0044 0.0048 0.005 0.0058
Al 0.0019 0.0054 0.006 0.0022
Cu 0.04 0.04 0.041 0.041
Co 0.001 0.001 0.001 0.001
Ti 0.002 0.0022 0.0023 0.0021
Nb 0.001 0.001 0.001 0.001
V 0.001 0.001 0.001 0.001
W 0.0099 0.009 0.012 0.015
Pb 0.001 0.001 0.001 0.001
Mg 0.0004 0.0004 0.0004 0.0005
B 0.0007 0.0006 0.0007 0.0007
Sb 0.0067 0.0065 0.0072 0.0095
Sn 0.0031 0.0033 0.0034 0.0031
Zn 0.001 0.001 0.001 0.001
As 0.012 0.011 0.011 0.011
Bi 0.008 0.0076 0.0085 0.009
Ce 0.002 0.002 0.002 0.002
Zr 0.0015 0.0015 0.0015 0.0015
La 0.0005 0.0005 0.011 0.0005
Se 0.013 0.011 0.013 0.012
N 0.0034 0.0027 0.003 0.0034
Fe 94.3 94 94 94.4
Equivalent Carbon CE,% 4.09 4.13 4.09 3.99
Eutectic Carbon Cc 3.80 3.69 3.70 3.81High
purity
pig ironChemical composition, [wt.%]
C Si Mn P S Cr
3.64 1.22 0.47 0.02 0.016 0.04
TSEFCooling rate, dt/d °C/s
(-)0Temperature,T, °C
0
(+)TALTmTM
Time,sTime,sTst
Tmst
TEM
FDESTrTEUTER
Ts TES
T3T2T1SOLIDIFICATION CONTROL BY THERMAL ANALYSIS OF La/Ba INOCULATED
GREY CAST IRON
Eduard -Marius Stefan ,Mihai Chi șamera
POLITEHNICA University of Bucharest, Romania ;
I. INTRODUCTION
II. EXPERIMENTAL PROCEDURE
III. RESULTS
IV. CONCLUSIONS•Thermal analysis isused infoundry forcontrol ofstructure and properties ofcast irons .Here ispresented theexperimental study realized tocontrol theinoculation effect bythermal analysis method ofinoculated grey cast irons .
For this purpose was conducted aninladle inoculation process with 0.5wt.%inoculant from LaCaAlFesi and BaCaAlFeSi alloy systems .The main goals ofthis experimental research work are:toestablish theparticular
characteristics oftheregistered cooling curves, toemphasize thesolidification parameters that show more sensibility asagainst Laaddition intreated cast iron and eventually toimprove thermal analysis technique ofcontrol ofLa-
inoculated gray cast irons .Forverification ofthecorrectness oftheresults established bythermal analysis was conducted another setsofanalyses byother control methods that included chilling tendency, theevaluation ofgraphite
structures using optical microscopy andBrinell hardness tests .
The Paper Objective:•The main objectiv eof this experimental rese arch is to realize acooling curve parameters comparative analysis of two La/BaCaAlFeSi inoculated irons for evaluate and deeper
understanding of the mechanism of La and Ba inoculated cast irons solidification.
Table 1. Chemical composition of charge material
Table 2. Chemical composition of inoculants
Fig.1. Technical schedule of the experimental program
Fig.5 Graphite Morphology in un -inoculated, 0.5 wt. (%) Ba
alloy and 0.5 wt. (%) La alloy (etched 4 % Nital ) for chill wedge
samplesFig.2. Typical c ooling curve partameters of h ipoeutectic
irons and its first derivativesThe base iron was melted incoreless induction furnace
(acid lined, 150 kg,2400 Hzfrequency) .Ascharge material :
100wt%high purity pigiron were used (70kg).
The thermal regime ofcharge material process :overheating
temperature Ts=1530 șC;pouring temperature Tp=1330 șCfor
thegrey cast iron;inoculation -0.5wt%FeSiCaBa 0.2-0.7;
Table 3. The chemical compositions of overheated
base iron and of untreated and treated poured irons
Theinfluence ofinoculation treatment isclearly visible inthermal cooling curve analysis andtheother tools–chilling tendency, hardness tests andgraphite morphology
-used forcontrolling thecooling curve analysis results isreconfirming about thevalidity ofthismethod .
The LaCaAlFeSi alloy hasagood efficiency incast iron inoculation treatment but, because ofhishigh price inthemarket, theBaCaAlFeSi alloy isalso agood choise to
adopt infoundry work .•Graphite morfology wasvisibly changed bytype ofinoculant added .
•Baalloy hasthestrongest effect buttheneuniformity ofgraphite isaminus forhiseffect .Laalloy isnotasefficient asBaalloy butitchange thesizeof
graphite inanuniform waysothegeneral proprieties ofironisbetter .
•Themaximum degree ofundercooling (∆Tm) isstronger inLaalloys then inBaalloy inoculant
•Therecalescence (∆Tr)withhigh sensitiveness both ongraphitization potency andgraphite morphology wasstrong changed byinoculation .Thehigher
influence isforBaalloy butLaisalso near tohim.
•Therateofrecalescence (TEM) aswellas,thefirstderivative value attheendofsolidification (FDES) areinfluenced byinoculant addition andhasthe
same aspect mentioned before .•The chemical compositions forbase irons, after
melting and oholding atoverheating temperature,
andforpoured–uninoculated andinoculated –irons
arepresented inTable 3.Allirons are, chemically
speaking, near eutectic point onFeC phase diagram .
•Chilling tendency was studied and inthisrespect
themacro analysis hasrevealed thatallsamples was
well inoculated and noone, except uninoculated
sample, has chill area insurface .Forthat reason
was taken afurther approach inmicroscopical level
of research .The study showed that only
uninoculated sample hascementite instructure (Fig.
3)
•Theresults ofhardness testing–showed infigure 4-
confirmed thetendency revealed bychilling tendency
research .
•The relative performance of inoculants to control
representative thermal analysis parameters was calculated to
determine theefficiency oftheexperimental alloys .The
relative performance (RPi)ofinoculants –i-isestimated as:
where Xikismeasured value ofproperty –k-using inoculants –
i-;CLk isaverage value forproperty set–k-;Skisstandard
deviation from the set.Thermal analysis performance is
averaged andused asoneparameter –k-.Average performance
haslevel 0%.
TM -maximum temperature ofthe
poured melt,oC;
TAL -temperature of austenitic
liquidus,oC;
TSEF -temperature ofthe start of
eutectic freezing (nucleation),oC;
TEU – temperature of eutectic
undercooling,oC;
TER -temperature ofthe graphitic
recalescence,oC;
TES -temperature of the end of
solidification (end ofsolidus)oC;
TEM -maximum recalescence rate,
oC/sec ;
Tst–graphitic eutectic equilibrium
temperature,oC;
Tmst–carbide eutectic equilibrium
temperature,oC;
∆Tm–maximum degree ofundercooling
(∆Tm= Tst-TEU),oC;
∆Tr–recalecence degree(∆Tr=TER –
TEU),oC;
∆Ts–range ofequilibrium eutectic
temperature (∆Ts= Tst-Tmst),oC;
FDES -minimum value ofthe first
derivative ofcooling curve attheend of
eutectic solidification,oC;
∆T1=TEU -Tmst ;∆T2=TER-Tmst ;∆T3=
Tmst–TES
0.0 0.06.2
01234567
BaCaAlFeSi LaCaAlFeSi UIDistance from apex of the wedge, [mm]
Inoculant typeChill Tendency
0100200300400500600700800900
max.500µm max.250µm max.120µm max.60µm max.30µm max.15µmGraphite number of particles
Size class of graphite, [ mm]Dimensional distribution of graphite for Uninoculated
iron
5 mm
10 mm
15 mm
20 mm
25 mmDistance from apex
of wedge
0100200300400500600700800900
max.500µm max.250µm max.120µm max.60µm max.30µm max.15µmGraphite number of particles
Size class of graphite, [ mm]Dimensional distribution of graphite for BaCaAlFeSi
inoculated iron
5 mm
10 mm
15 mm
20 mm
25 mmDistance from apex
of wedge
0100200300400500600700800900
max.500µm max.250µm max.120µm max.60µm max.30µm max.15µmGraphite number of particles
Size class of graphite, [ mm]Dimensional distribution of graphite for LaCaAlFeSi
inoculated iron
5 mm
10 mm
15 mm
20 mm
25 mmDistance from apex
of wedgeDistance
from the
apexUninoculated BaCaAlFeSi LaCaAlFeSi
5 mm.
10 mm.
15 mm.
20 mm.
25 mm.
InoculantTM TAL TSEF TEU TER TES TEM FDES
Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC]
BaCaAl 1265.58 1178.67 1164.78 1147.54 1150.19 1109.16 0.13 -4.66
LaCaAl 1240.19 1180.53 1170.03 1147.22 1150.31 1113.06 0.15 -5.14
UI 1257.38 1194.53 1176.37 1137.23 1144.23 1103.53 0.32 -4.18
InoculantTst Tmst(T) Ts(T) ΔTm ΔTr ΔT1(T) ΔT2(T) ΔT3(T)
Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC] Val.[oC]
BaCaAl 1165.13 1125.28 39.85 17.58 2.65 22.26 24.91 -16.12
LaCaAl 1164.86 1125.76 39.10 17.64 3.09 21.46 24.55 -12.70
UI 1162.51 1129.96 32.55 25.28 6.51 7.75 14.27 -26.43
Inoculant TM TAL TSEF TEU TER TES TEM FDES
CLk 1254.38 1184.58 1170.39 1144.00 1148.24 1108.58 0.20 -4.66
Sk 9.46 6.63 3.99 4.51 2.68 3.37 0.08 0.32
RpiBaCaAl 118.35 -88.97 -140.84 78.58 72.84 17.09 -86.84 -1.71
LaCaAl -150.00 -61.03 -9.16 71.42 77.16 132.91 -63.16 -148.29
UI 31.65 150 150 -150 -150 -150 150 150
Inoculant Tst Tmst (T) Ts(T) ΔTm ΔTr ΔT1(T)ΔT2(T)ΔT3(T)ΔTEU I2
CLk 1164.17 1127.00 37.17 20.17 4.08 17.16 21.24 -18.42 – –
Sk 1.10 1.97 3.08 3.41 1.62 6.27 4.65 5.34 – –
RpiBaCaAl 87.16 -87.16 87.16 -75.80 -88.52 81.40 78.92 42.97 10.31 -7.70
LaCaAl 62.84 -62.84 62.84 -74.20 -61.48 68.60 71.08 107.03 9.99 -7.64
UI -150 150 -150 150 150 -150 -150 -150 – -The thermal regime ofcharge material process :superheating temperature Ts=1560 șC;pouring
temperature Tp=1380 -1317 șC;inladle treatment inoculation -0.5wt%,one ladle with BaCaAlFeSi and
another onewith LaCaAlFeSi .
The poured samples :OES–sample foroptical electron spectrometry chemical analysis ;Quik –
Cup,0.39cooling moduls ,350gweight ,mass density -ρ=7.04[g/cm³] forQuik -labrapid analysis and
Cooling Curve data acquisition ;andthree wedge samples poured insand mould (Figure 1ispresenting
theschedule ofthepouring program .
The chemical compositions charge material and ofinoculants arepresented inTable 1and Table 2
respectively .,while, inFigure 2isintroducing thetypical aspect ofCooling curve andit’sparameters .
Fig.3. Measured chilled area and microstructural aspect
of poured irons
Fig.4. HB test results on poured irons
Fig.6 Graphite -classified by size -in wedge samples
(from 5 mm. of apex and in steps of 5 mm until to the
top of sample) in uninoculated , 0.5 wt. (%) Ba alloy and
0.5 wt. (%) La alloyTable 4. Thermal Analysis Representative Parameters
Table 5. Relative performance of inoculants in representative temperatures on the cooling curves
composition