x&xi cast iron
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METALLURGY II(RM-1421)
Dosen:
Wahyu Wijanaro
Me!hani!a" En#ineerin#
IT$- $ura%aya
Introduction
Classifications of Cast Iron
Chemical Composition of Cast Iron
Cooling Rate of Cast Iron
Phase Diagram of Cast Iron
Schematic of Types of Cast Iron
Alloying Elements
Jadwal kuliah :
Tiap hari Selasa pukul 19.40 21.20 Ruang c-119
MINGGU X&XIMINGGU X&XI
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Inrou!ionInrou!ion
Family of ferrous alloys
Cast into desired shape 2!" C # $%" Si
Properties affected &y'( chemical composition
( solidification process
( solidification rate
( heat treatments
)ide range of strengths and hardness
In most cases are easy to machine *ood hardness+ ,ear resistance and corrosion
resistance effect of alloying elements
-o, cost and .ersatile engineering properties
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+"assi,i!aions o, +as Iron+"assi,i!aions o, +as Iron
()hite cast iron
(/allea&le cast iron
(*ray cast iron
(0odular1Ductile cast iron
(igh alloys cast iron
$3 4lasifi5asi tergantung
dari &entu5 grafit 6Cyang &er5umpul7+ atau5ar&ida yang ter&entu5+dan stru5tur mi5rodominan3
23 Tergantung 8uga oleh '4omposisi 5imia+ -a8upendinginan+ danPerla5uan panas3
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+hei!a" +o.osiion o, +as Iron+hei!a" +o.osiion o, +as Iron
Faktor yang
berpengaruh terhadappembentukan jenis besituang :
% C
% Si
Temperatur (Cooling
rate)
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0hase Dia#ra o, +as Iron0hase Dia#ra o, +as Iron
G
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0hase Dia#ra o, +as Iron0hase Dia#ra o, +as Iron
9ila ter8adi pendinginan &esi tuang melalui garis
:Eutectic; dari
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$!heai! o, Ty.es o, +as Iron$!heai! o, Ty.es o, +as Iron
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$!heai! o, Ty.es o, +as Iron$!heai! o, Ty.es o, +as Iron
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$!heai! o, Ty.es o, +as Iron$!heai! o, Ty.es o, +as Iron
Irre#u"arsha.enou"e
5rosee
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Whie +as IronWhie +as Iron
Chemical composition'
( Car&on $3%3B "( Silicon 3$3 "
( /anganese 323 "
( Sulfur 3B32 "
( Phosphorus 3B3$ "
Solidification rate fast enough
Car&on com&ined ,ith iron cementite 6hard+
&rittle7 /icrostructure pearlite in a ,hite interdendritic
net,or5 of cementite
Sho,s a
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Whie +as IronWhie +as Iron
igh compressi.e strength and ecellent ,ear resistance
&ut etremely &rittle and difficult to machine Gsed ,here'
( resistance to ,ear is most important
( The ser.ice does not re@uire ductility
)hite cast iron /allea&le cast iron 6mallea&iliHation7
/echanical properties'( ardness &rinell % ( B 90
( Tensile strength 23 ( 3 psi
( Compressi.e strength 23 ( 23 psi
( /odulus of elasticity 2! ( 2 milionpsi
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Whie +as IronWhie +as Iron
Pada % '
rea5si eutectic
li@uid ? Fe%C 6lede&urite7
Pada !'
rea5si eutectoid
? Fe%C 6pearlite7
Fasa li@uid primer
4omposisi !3%" C 6titi5 E7 2" C 6titi5 C7
Jumlahrelatif 22" "
Pada $ ' fasa li@uid
5omposisi 5imia 23"C
8umlah relatif $"
Pada 2 ' mulai ter&entu5 primer
Fasa Fe%C ? primer
4omposisi B3B" C 6titi5 D7 2" C 6titi5 C7
Jumlahrelatif $$" "
Fasa Fe%C ? primer
4omposisi B3B" C 6titi5 47 3" C 6titi5 J7
Jumlahrelatif 2" $"
Fasa Fe%C
4omposisi B3B" C 32" C
Jumlahrelatif %" B%"
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Whie +as IronWhie +as Iron
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Ma""ea%"e +as IronMa""ea%"e +as Iron
Chemical composition'
( Car&on 2323B "( Silicon $3$$3B "
( /anganese 32$3 "
( Sulfur 3!3$ "
( Phosphorus 3$ " ma )hite cast iron /allea&le cast iron 6mallea&iliHation7
Car&on in the form of irregularly shaped nodules ofgraphite
Cementite irregularly shaped nodules graphite
/allea&iliHation'( First stages of the anneal
( Second stages of the anneal
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Ma""ea%"e +as IronMa""ea%"e +as Iron
First stages
(Reheated to $B and $oF(Austenite of the metasta&le
system can dissol.e more
car&on than can austenite of the
sta&le system
(Dri.ing force for the car&on toprecipitate out of the austenite
as free graphite 6temper car&on7
(Structure at completion of first
stages graphitiHation consist of
temper car&on nodulesdistri&uted throughout the
matri of saturated austenite
(Cooled as rapidly as practical
to a&out $!oF
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Ma""ea%"e +as IronMa""ea%"e +as Iron
Second stages
(Slo,ly cooled at a rate of to
$oF1h
(The car&on dissol.ed in the
austenite is con.erted to graphite on
the eisting temper car&on particles+
and the remaining austenitetransforms into ferrite
(The structure consist of temper
car&on nodules in a ferrite matri
6ferritic mallea&le iron7
(Temper car&on nodules does not
&rea5 up the continuity of the tough
ferritic matri3 This result in a
higher strength and ductility than
ehi&ited &y gray cast iron
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Ma""ea%"e +as IronMa""ea%"e +as Iron
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Ma""ea%"e +as IronMa""ea%"e +as Iron
Second stages
( Fast enough cooled to retainedcom&ined car&on throughoutthe matri
( If the air @uenched produces afast enough cooling ratethrough the eutectoid range+
the matri ,ill &e completelypearlitic
( The strength and hardness ofthe castings ,ill &e increasedo.er those of ferritic mallea&leiron
Type Tensile
Strength
$ Psi
Kield
Strength
$ Psi
Elongation
" in 2 in
90
Ferritic B %2% 2$ $$$!
Pearlitic B$2 !$ $B2 $B%2B
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Ma""ea%"e +as IronMa""ea%"e +as Iron
Second stages(If the cooling rate through the
critical range is not @uite fastenough to retain all thecom&ined car&on+ the areassurrounding the temper car&onnodules ,ill &e completelygraphitiHed+ ,hile those atgreater distance from thenodules ,ill &e pearlitic3
(9ecause of its generalappearance+ this is referred to
as a bulls-eyestructure
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Ma""ea%"e +as IronMa""ea%"e +as Iron
Pearlitic mallea&le irons
tempered at relati.ely hightemperatures spheroidiHethe pearlite
Impro.e machina&ility and
toughness+ and lo,er thehardness
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Gray +as IronGray +as Iron
Chemical composition'
( Car&on 23!3 "
( Silicon $3%3 "
( /anganese 32$3 "
( Sulfur 3232 "
( Phosphorus 3$3 "
Car&on in the iron separates or graphitiHes during
solidification to form separate graphite fla5es
The most fluid of the ferrous alloys a.e ecellent machina&ility
Fracture surface appearance has a gray color
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Gray +as IronGray +as Iron
The graphitiHation process is
aided &y high car&on content+high temperature+ and theproper amount of graphitiHingelements+ nota&ly silicon
)ith proper control of the
a&o.e factors+ the alloy ,illfollo, the sta&le irongraphitee@uili&rium diagram
These alloys solidify &y firstforming primary austenite
Forming austenite and graphiteat the eutectic temperature of2oF
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Gray +as IronGray +as Iron
The graphite appears as
many irregular+ generally
elongated and cur.ed
plates3 The fla5e are three
dimensional particles
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Gray +as IronGray +as Iron
The strength the matri
This matri the condition of the
eutectoid cementite
The eutectoid cementite alsographitiHes+ then the matri ,ill &eentirely ferritic
*raphitiHation of the eutectoid
cementite is pre.ented+ the matri,ill &e entirely pearlitic
The matri'
6pearlite7(6pearlite#ferrite7(6ferrite7
*raphiteferrite softest and
,ea5est
Com&ined car&on increased
strength and hardness increased
*raphitepearlite strongest and
hardest
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Gray +as IronGray +as Iron
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METALLURGY II a yu ja a o
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Gray +as IronGray +as Iron
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A""oyin# E"eens in Gray +as IronA""oyin# E"eens in Gray +as Iron
Silicon
(Increased fluidity(*raphitiHer car&on is precipitated as primary graphite in the
form of fla5es during solidification
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A""oyin# E"eens in Gray +as IronA""oyin# E"eens in Gray +as Iron
Sulfur
(Restrict graphitiHation(Sulfur L com&ined car&on L hard+ &rittle ,hite iron
(Reduce fluidity
(Responsi&le for the presence of &lo,holes in casting
(Com&ined ,ith iron FeS
Manganese()ea5ly retard primary graphitiHation
(Strong car&ide sta&iliHer on eutectoid graphitiHation
(Promote pearlite formation
(Com&ined ,ith sulfur /nS
(/anganese content t,o or three times the sulfur content
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A""oyin# E"eens in Gray +as IronA""oyin# E"eens in Gray +as Iron
Phosphorus
(Com&ined ,ith iron Fe%P 6iron phosphide
called steadite7
(Steadite is hard and
&rittle(Increased steadite increased its hardness+
&rittleness+ ,earresistance and decreased
machina&ility(Increased fluidity
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7ea Treaen o, Gray +as Iron7ea Treaen o, Gray +as Iron
Stress relieving
(The most fre@uently heattreatment
(*ray iron in the ascast residual stresses differentof cooling rates
(Residual stresses reduce
strength+ distortion+ andcrac5ing
(The temperature &elo,eutectoid temperature
(olding time $ h #
temperature of $$oF stress relief o.er percent
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METALLURGY II
|Jurusan Teknik Mesin ITS|&'&I - *1
7ea Treaen o, Gray +as Iron7ea Treaen o, Gray +as Iron
Annealing
(eating
high enough to soften and impro.e machina&ility(Annealing temperature $% ( $!oF 6recommended7
(eld at temperature long enough to allo, the graphitiHing process to go tocompletion
Normalizing(Treated to a temperature a&o.e the transformation range
(eld at this temperature for a period of a&out $ h1in3 of maimum sectionthic5ness
(Cooled in still air to room temperature
(0ormaliHing temperature $B2 $oF(Gsed to enhance mechanical properties+ such as hardness and tensile
strength
(To restore ascast properties that ha.e &een modified &y another heattreatment process
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METALLURGY II
|Jurusan Teknik Mesin ITS|&'&I - *2
7ea Treaen o, Gray +as Iron7ea Treaen o, Gray +as Iron
Hardening(Furnacehardened from a temperature of $$BoF
(Muenched from a suita&le ele.ated temperature
(Muenching medium' air+ salt &ath+ oil or ,ater
(Nil throughhardening
()ater too drastic and may cause crac5ing and distortion unless thecastings are massi.e and uniform in cross section
()ater often used for @uenching ,ith flame and induction hardening
(As@uenched &rittle
(Tempered from %$2oF to increase toughness and relie.e stresses
(Tempered impro.es strength and toughness &ut decreases hardness
(Muenched and tempered not ordinarily used to increased strength strength can &e increased at less cost &y reducing silicon and total car&oncontent or &y adding alloying elements
(Muenched and tempered increase the resistance to ,ear and a&rasion &yincreasing the hardness
(A structure consisting of graphite em&edded in a hard martensitic matri
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METALLURGY II
|Jurusan Teknik Mesin ITS|&'&I - **
Gra.hie 8"ae o, Gray +as IronGra.hie 8"ae o, Gray +as Iron
*raphite fla5es L interrupt the continuity of the pearlitic matri
O the strength and ductility *raphite fla5es O less damaging generally preferred
ypoeutectic iron slo, cooling graphitiHation # crystals ofprimary austenite L restricts the eutectic miture or graphite tothe grain &oundary graphite fla5es fe, in num&er and coarse
Car&on content L the amount of eutectic # graphite formed L ,ea5en more than a smaller fla5e siHe can strengthen it
Silicon content 6strong graphitiHing7 L the amount of eutecticformed L reducing fla5e siHe the matri ,ill ferritic ,ea5
casting Reducing the siHe and impro.ing the distri&ution of the graphite
fla5e addition of a small amount of material 6inoculant7
Inoculating agents metallic calcium+ aluminum+ titanium+Hirconium+ silicon car&ide+ calcium silicide+ or com&inations of these
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METALLURGY II
|Jurusan Teknik Mesin ITS|&'&I - *4
Gra.hie 8"ae o, Gray +as IronGra.hie 8"ae o, Gray +as Iron
The procedure for preparation and measurement of fla5e siHe is
gi.en in AST/ Designation A2!B+ $$ 9oo5 of AST/Standards+ Part %$
The measurement is made of the lengths of the largest graphitefla5es in a unetched section at $
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METALLURGY II
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Gra.hie 8"ae o, Gray +as IronGra.hie 8"ae o, Gray +as Iron
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METALLURGY II
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Gra.hie 8"ae o, Gray +as IronGra.hie 8"ae o, Gray +as Iron
*raphite fla5es are arranged in the microstructure prepared &y
the AFS and the AST/
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METALLURGY II
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Gra.hie 8"ae o, Gray +as IronGra.hie 8"ae o, Gray +as Iron
Type D and E
(From the graphitiHation of a normal eutectic structure(Appear in irons of .ery high purity or in commercial irons that ha.e &eencooled rather rapidly during solidification
(Although the graphitic fla5e siHe is small+ the interdendritic pattern andhigh graphite content ,ea5en the material
(Type D and E undesira&le in gray irons
()hen cooling rate is slo,er sho, complete di.orcement of the eutectictype D and E fla5e patterns do not occur
Type A
(The most desira&le fla5e pattern(This results from a completely di.orced eutectic structure
(The siHe of the indi.idual graphite fla5es is determined &y the siHe of theaustenite crystals around ,hich they form
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METALLURGY II
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Gra.hie 8"ae o, Gray +as IronGra.hie 8"ae o, Gray +as Iron
Type 9
(Common only in the intermediate region of a chilled cast iron 6mottled7(Consist of a miture of gray and ,hite cast iron
(The cooling rate is maimum that ,ould permit graphitiHation
Type C
(The fe, large+ straight graphite fla5es present in type C al,ays indicate thatthe iron is hypereutectic in car&on content
(Silicon and se.eral other alloying elements reduce the car&on content of theeutectic+ and if they are present in sufficient amounts the eutecticcomposition may &e reduced to &elo, %3 percent car&on
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METALLURGY II
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Me!hani!a" 0ro.eries ' A.."i!aion o, Gray +as IronMe!hani!a" 0ro.eries ' A.."i!aion o, Gray +as Iron
The gray cast iron are classed in se.en classes 60os3 2+ 2+ %+
%+ !+ + B7 ,hich gi.e the minimum tensile strength of test&ars in thousand of pounds per s@uare inch3(Class 2 minimum tensile strength of 2 psi
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Me!hani!a" 0ro.eries ' A.."i!aion o, Gray +as IronMe!hani!a" 0ro.eries ' A.."i!aion o, Gray +as Iron
Tensile strength(
Tensile strength is important for part thatare su&8ected to static load in indirecttension or &ending3 Such parts include
pressure .essels+ housing+ .al.es+ fittingsand le.ers
(Iron a&o.e ! psi in tensile strength are
usually considered high-strength ironsandare more epensi.e to produce and moredifficult to machine
(*ray irons do not ehi&it a ,elldefined yield point as do most mild steels
(The stressstrain cur.e does not sho, a straight line portionQ thus a definitemodulus of elasticity cannot &e determined
(Gsual method are to determined the
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Me!hani!a" 0ro.eries ' A.."i!aion o, Gray +as IronMe!hani!a" 0ro.eries ' A.."i!aion o, Gray +as Iron
Compressi.e strength(
Compressi.e strength is important ,hen the gray iron is used for machineryfoundations or supports
(-i5e all &rittle material+ the compressi.e strength of gray iron is muchgreater than its tensile strength and is largely a function of the shearingstrength
(Failure in compression usually occurs along an o&li@ue plane unless the
specimen is long enough to allo, failure &y &uc5ling
Torsional shear strength(/any grades of gray iron ha.e higher torsional shear strength than some
grades of steel(This characteristic+ along ,ith lo, notch sensiti.ity+ ma5es gray iron asuita&le material for types of shafting
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Me!hani!a" 0ro.eries ' A.."i!aion o, Gray +as IronMe!hani!a" 0ro.eries ' A.."i!aion o, Gray +as Iron
Compressi.e strength(
Compressi.e strength is important ,hen the gray iron is used for machineryfoundations or supports
(-i5e all &rittle material+ the compressi.e strength of gray iron is muchgreater than its tensile strength and is largely a function of the shearingstrength
(Failure in compression usually occurs along an o&li@ue plane unless the
specimen is long enough to allo, failure &y &uc5ling
Torsional shear strength(/any grades of gray iron ha.e higher torsional shear strength than some
grades of steel(This characteristic+ along ,ith lo, notch sensiti.ity+ ma5es gray iron asuita&le material for types of shafting
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METALLURGY II
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Me!hani!a" 0ro.eries ' A.."i!aion o, Gray +as IronMe!hani!a" 0ro.eries ' A.."i!aion o, Gray +as Iron
ardness(
The hardness is an a.erage result of the soft graphite in the iron andmetallic matri
(ariation in graphite siHe and distri&ution ,ill cause ,ide .ariations inhardness 6particularly Roc5,ell hardness7
(The &rinel tester+ co.ering a larger area+ tend to gi.e a more accuratehardness .alue than Roc5,ell test
(Compressi.e strength steadily increases ,ith increasing hardness
(The microstructure is the primary factor in determining the hardness of grayiron
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Me!hani!a" 0ro.eries ' A.."i!aion o, Gray +as IronMe!hani!a" 0ro.eries ' A.."i!aion o, Gray +as Iron
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U G
|Jurusan Teknik Mesin ITS|&'&I - 4/
+hi""e +as Iron+hi""e +as Iron
Chillediron casting are made &y casting the moltenmetal against a metal chiller+ resulting in a surface of
,hite cast iron Case hard+ a&rasionresistant ,hite iron
Core softer gray iron
This casecore structure is o&tained &y careful controlof the o.erall alloy composition and ad8ustment of the
cooling rate 0ormal cooling rate at the surface is 8ust fast enough to
produce ,hite iron ,hile the slo,er cooling rate &elo,the surface ,ill produce mottled or gray iron
If only selected area to &e ,hite iron+ it is common
practice to use a composition ,hich ,ould normallysolidify as gray iron and employ metal liners 6chills7 toaccelerate the cooling rate of the selected areas
The depth of the ,hiteiron layer is controlled &y usingthin plates ,hene.er a thin ,hiteiron layer is desiredand hea.ier metal plates ,here the deeper chill is
necessary
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Car&on(decreases the depth of chill and increases the hardness of the chilled Hone
Silicon 6graphitiHer7(decreases the depth of chill
/anganese(decreased the depth of chill until the sulfur has &een neutraliHed &y formation
of manganese sulfide(A&o.e this amount+ manganese increases chill depth and hardness
Phosphorus(decreases the depth of chill
0ic5el(reduces the chill depth+ and its influence is a&out onefourth that of silicon(*radual increase in hardness until the nic5el content reaches a&out percent
(Refines the car&ide structure of the chill and the grayiron structure &elo, thechill
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Chromium(9ecause of the formation of chromium car&ides+ chromium is used in amount
of $ to ! percent in chilled irons to increase hardness and impro.e a&rasionresistance
(Sta&iliHes car&ide and suppresses the formation of graphite in hea.y section
()hen added in amount of $2 to % percent+ chromium ,ill impart resistanceto corrosion and oidation at ele.ated temperature
Cooper(In additions of less than ! percent+ decreases the depth of chill
(In ecess of this amount the chill depth and hardness increase
(Reduces ration oh the mottled portion to the ,hiteiron portion
/oly&denum(A&out onethird as effecti.e as chromium in increasing the chill depth
(Impro.es the resistance of the chilled face to spalling+ pitting+ chipping andheat chec5ing
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A constant chill depth may &e o&tained &y using a com&ination ofalloying elements that ha.e opposite effect
Since nic5el reduces chill depth+ it common practice to addchromium+ ,hich increases chill depth+ to neutraliHe the nic5el andresult in a constant chill depth
Chillediron casting is used for rail,aycar ,heels+ crushing rolls+
stamp shoes and dies+ sproc5ets+ plo,shares and many other hea.yduty machinery parts
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Chemical composition'
( Car&on %3!3 "( Silicon $323 "
( /anganese 3$$3 "
( Sulfur 3%" ma
( Phosphorus 3$" ma
4no,n as ductile iron, spheroidal graphite ironand
spherulitic iron
*raphite is present as tiny &alls or spheroids The compact spheroids interrupt the continuity of the
matri much less than graphite fla5es higher strength
and toughness compared ,ith gray iron
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0odular cast iron differs from mallea&le iron in that is
usually o&tained as a result of solidification and doesnot re@uire heat treatment
0odular spheroids car&on
/allea&le irregular temper car&on
Spheroidal graphite particles form during solidification
&ecause of the presence of a small amount of certain
alloying elements+ usually magnesium or cerium
Since these elements ha.e a strong affinity for sulfur+the &ase iron alloy sulfur content must &e &elo, 3$
percent desulfuriHed
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The amount of ferritein the ascast matri
depends oncomposition and rateof cooling
0odular irons ,ith amatri ha.ing a
maimum of $percent pearlite are5no,n asferritic irons
This structure gi.esmaimum ductility+toughness and
machina&ility
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Pearlite can &e produced as cast or &y normaliHing
0ormaliHing is carried out &y air cooling from temperature of$B to $BoF
Peralitic ductile irons are stronger &ut less ductile than ferrite
irons
A martensitic matri may &e o&tained &y @uenching in oil or,ater from $B to $oF3 The @uenched structures are usually
tempered+ after hardening+ to the desired strength and hardness
le.els
Austenitic ductile irons are highly alloyed types ,hich retainaustenitic structure do,n to at least oF3 These irons are of
interest &ecause of their relati.ely high corrosion resistance and
good creep properties at ele.ated temperatures
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Application
Agricultural' tractor and implement parts
Automoti.e and diesel' cran5shafts+ pistons and cylinder headsQ
electrical fittings+ s,itch &oes+ motor frames+ and circuit &rea5er
parts
/ining' hoist drums+ dri.e pulley+ fly,heels and ele.ator &uc5ets
Steel mill' ,or5 rolls+ furnace doors+ ta&le rolls and &earings
Tool and die' ,renches+ le.ers+ handles+ clamp frames+ chuc5 &odies
and miscellaneous dies for shaping steel+ aluminum+ &rass+
&ronHe+ and titanium
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A""oy +as IronA""oy +as Iron
Added elements in sufficient amount to produce
modification in the physical or mechanical properties( Resistance to corrosion+ heat and ,ear
( To impro.e mechanical properties
Nne of the important reasons for alloying is accelerate
or retard graphitiHation
Elements o&tained from ra, material+ such as silicon+
manganese+ sulfur+ and phosphorus+ are not considered
alloy additions The most common alloying elements are chromium+
copper+ moly&denum+ nic5el and .anadium
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METALLURGY II(RM-1421)
Dosen:
Wahyu WijanaroMe!hani!a" En#ineerin#
IT$- $ura%aya
!""!SI!N!""!SI!N
MINGGU XIIMINGGU XII
Jadwal kuliah :
Ti h i S l k l R