Callister - An introduction - 8th edition

400 • Chapter 11 / Applications and Processing of Metal Alloys
Figure 11.2 The
true equilibrium
iron–carbon phase
diagram with
graphite instead of
cementite as a stable
phase. [Adapted
from Binary Alloy
Phase Diagrams,
T. B. Massalski
(Editor-in-Chief),
1990. Reprinted by
permission of ASM
International,
Materials Park, OH.]
Temperature (°C)
Composition (at% C)
0 5 10 15 98
1600
1400
1200
1000
800
(Austenite)
+ L
Liquid
1153°C
2.1 wt% C
740°C
4.2 wt% C
+ Graphite
Liquid
+
Graphite
2500
2000
1500
Temperature (°F)
600
0.65 wt% C
(Ferrite)
+ Graphite
1000
400 0 1 2 3 4
Composition (wt% C)
90 100
Graphite
gray cast iron
Gray Iron
The carbon and silicon contents of gray cast irons vary between 2.5 and 4.0 wt%
and 1.0 and 3.0 wt%, respectively. For most of these cast irons, the graphite exists
in the form of flakes (similar to corn flakes), which are normally surrounded by an
-ferrite or pearlite matrix; the microstructure of a typical gray iron is shown in Figure
11.3a. Because of these graphite flakes, a fractured surface takes on a gray appearance,
hence its name.
(a)
20 m
(b)
50 m