A survey is made of changes in crystalline structure of polycrystalline metals and large single crystals subjected to deformation by cold-work and by static and cyclic stressing, observations being made by a combination of mechanical, metallographic and x-ray tests. It is shown that the grains may be dispersed into crystallites characterized by a lower limiting size depending on the metal and that it is possible to observe internal lattice strains which it is considered are related to the process of strain hardening. It is also shown that the response of the crystalline structure depends on the manner and particularly the speed of application of stress, and that it is possible in this way to inhibit the dispersed crystallite formation and suppress the primitive yield-point of a metal, thus varying the hardness independently of the external deformation.
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William A. Wood (1940) studied this question.