STRAIN
DOE-HDBK-1017/1-93
Properties of Metals
The important information in this chapter is summarized below.
Strain is the proportional dimensional change, or the intensity or degree of
distortion, in a material under stress.
Plastic deformation is the dimensional change that does not disappear when the
initiating stress is removed.
Proportional limit is the amount of stress just before the point (threshold) at which
plastic strain begins to appear or the stress level and the corresponding value of
elastic strain.
Two types of strain:
Elastic strain is a transitory dimensional change that exists only while the
initiating stress is applied and disappears immediately upon removal of the
stress.
Plastic strain (plastic deformation) is a dimensional change that does not
disappear when the initiating stress is removed.
g-iron face-centered cubic crystal structures deform more readily under load before
breaking than a-iron body-centered cubic structures.
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