Fundamentals of Materials Science and Engineering: An Integrated Approach, 3e

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2nd Revised Pages

528 • Chapter 13 / Types and Applications of Materials

(a)

(b)

Vibrational amplitude

Ti m e

Figure 13.4 Comparison of the relative

vibrational damping capacities of (a) steel and

(b) gray cast iron. (FromMetals Engineering

Quarterly,February 1961. Copyright 1961

American Society for Metals.)

ferrite, depending on heat treatment (Figure 13.5); it is normally pearlite for an as-cast

piece. However, a heat treatment for several hours at about 700◦C (1300◦F) will yield

a ferrite matrix as in this photomicrograph. Castings are stronger and much more

ductile than gray iron, as a comparison of their mechanical properties in Table 13.5

shows. In fact, ductile iron has mechanical characteristics approaching those of steel.

For example, ferritic ductile irons have tensile strengths ranging between 380 and

Commercial cast iron range

Fast cool Moderate Slow cool

P + Fe 3 C P + Gf α + Gf

Fe 3 C

Mg/Ce

C

Temperature

Moderate Slow cool

P + Gn α + Gn

Reheat: hold at

~ 700 °C for 30 + h

Fast cool Slow cool

P + Gr α + Gr

White

cast iron

Pearlitic gray

cast iron

Pearlitic

malleable

Ferritic

malleable

Ferritic gray

cast iron

Pearlitic

ductile

cast iron

Ferritic

ductile

cast iron

Figure 13.5 From

the iron–carbon

phase diagram,

composition ranges

for commercial cast

irons. Also shown are

schematic

microstructures that

result from a variety

of heat treatments.

Gf, flake graphite;

Gr, graphite rosettes;

Gn, graphite nodules;

P, pearlite;α, ferrite.

(Adapted from W. G.

Moffatt, G. W.

Pearsall, and J. Wulff,

The Structure and

Properties of

Materials,Vol. I,

Structure, p. 195.

Copyright©c1964 by

John Wiley & Sons,

New York.

Reprinted by

permission of John

Wiley & Sons, Inc.)