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

GTBL042-09 GTBL042-Callister-v3 October 4, 2007 11:53

2nd Revised Pages

9.8 Impact Fracture Testing • 311

10 mm

(0.39 in.)

Izod

Scale

Charpy

Pointer Starting position

End of swing

Specimen

Anvil

8 mm

(0.32 in.)

10 mm

(0.39 in.)

(a)

(b)

Notch

h'

Hammer

h

Figure 9.18 (a)

Specimen used for

Charpy and Izod

impact tests. (b)A

schematic drawing of

an impact testing

apparatus. The

hammer is released

from fixed heighth

and strikes the

specimen; the energy

expended in fracture

is reflected in the

difference betweenh

and the swing height

h′. Specimen

placements for both

Charpy and Izod

tests are also shown.

[Figure (b) adapted

from H. W. Hayden,

W. G. Moffatt, and

J. Wulff,The

Structure and

Properties of

Materials,Vol. III,

Mechanical Behavior,

p. 13. Copyright©c

1965 by John Wiley

& Sons, New York.

Reprinted by

permission of John

Wiley & Sons, Inc.]

fracture toughness tests are not as simple to perform as impact tests; furthermore,

equipment and specimens are more expensive.

Ductile-to-Brittle Transition

One of the primary functions of Charpy and Izod tests is to determine whether or

not a material experiences aductile-to-brittle transitionwith decreasing temperature

ductile-to-brittle

transition