Page 244 - Materials Science and Engineering An Introduction

C h a p t e r 7 Dislocations and

Strengthening Mechanisms

The photograph in Figure (b) is of a partially formed aluminum beverage can. The
associated photomicrograph in Figure (a) represents the appearance of the aluminum’s
grain structure—that is, the grains are equiaxed (having approximately the same
dimension in all directions).
Figure (c) shows a completely formed beverage can, fabrication of which is
accomplished by a series of deep drawing operations during which the walls of the can
are plastically deformed (i.e., are stretched). The grains of aluminum in these walls
change shape—that is, they elongate in the direction of stretching. The resulting grain
(a)
structure appears similar to that shown in the attendant photomicrograph,
Figure (d). The magnification of Figures (a) and (d) is 150 .

(b)

(c)

(The photo micrographs in figures (a) and (d) are taken from W. G. Moffatt, G. W. Pearsall,
and J. Wulff, The Structure and Properties of Materials, Vol. I, Structure, p. 140. Copyright
(d)
© 1964 by John Wiley & Sons, New York. Figures (b) and (c) © William D. Callister, Jr.)

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