Lecture 10 Cast Iron
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Transcript of Lecture 10 Cast Iron
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Dong-A University
Lecture 10. Cast iron
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Casting
Melting point
Shape forming
Property
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How to reduce M.P.
Microstructure
+ Fe3C ?
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Cementite vs. Graphite
Page 4
Super-saturated
+ Fe3C + C(graphite)
By carbon diffusion By MORE carbon diffusion
Meta-stable state Stable state
Formation condition
of cementite and graphite(pure carbon)
C content
Diffusion time
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Microstructures of cast iron
Page 5
(White cast iron) Cementite + pearlite
(gray cast iron) Ferrite + pearlite + flake carbon
(malleable cast iron) Ferrite + temper carbon
(Nodular/ductile cast iron) Ferrite/pearlite + nodular carbon
Chilled cast iron
Compacted/vermicular cast iron (C/V)
Austempered cast iron (ADI)
Alloyed cast iron
, , ,
Ausferrite acicular ferrite+carbon = stabilized austenite
Strongest cast iron
Si : , Al : Ni : Cr : ,
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Form Description of t
he form
Main spatial
characteristics Occurrence
I Lamellar (flake)
graphite
Interconnected particles
within eutectic cells;
lamellar (flake) graphite
with sharp ends
Principal form in grey cast iron
Austenitic cast iron with
lamellar/flake graphite
Can occur in the rim zone of other ca
st-iron materials
II Crab graphite Aggregate of graphite
flakes
Can occur in rapidly cooled
hypereutectic grey cast irons
Can also occur in segregation areas
of thick-walled spheroidal-graphite
cast-iron castings
III
Compacted (ve
rmicular)
Graphite
Usually interconnected par
ticles within eutectic
cells; worm-like
appearance with
rounded ends
Principal form in compacted-graphite
cast irons
Can occur in spheroidal graphite
cast irons
IV
Temper carbon
Irregular sphero
idal graphite*
Isolated particles Principal form in malleable cast irons
Can occur on spheroidal-graphite
cast iron
V
Slightly irregula
r spheroidal
Graphite
Isolated particles
Principal form in thick-walled casting
s made of spheroidal graphite cast ir
ons
Occurs to a specified extent in comp
acted-graphite cast irons
Can occur in malleable cast irons
VI Spheroidal gra
phite* Isolated particles
Principal form in castings made of
spheroidal-graphite cast irons
Occurs to a specified extent in
compacted-graphite cast irons
Table1: Graphite forms
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Si effect on Fe-C phase diagram
Page 10
+ Fe3C + L
Graphite(or Fe3C)
stabilizing
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Solidification sequence
Page 11
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Eutectic cell and nodule counts
Page 12
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Graphite in gray cast iron ASTM A247-10
Page 13
Fast cooling Low C.E.
Slow cooling
A+D Hyper-eutectic
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Graphite microstructure ASTM A247-10
Page 14
Type A
Type B
Type C
Type D
Type E
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Inoculation
Page 15
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Phases during austempering treatment