Relation Of Crystal Orientation To Bending Qualities Of A Rolled Zinc Alloy

THE development of "fiber" or preferred orientations, during the plastic deformation of metals, and the relation of such structures to the anisotropic characteristics of worked metals has become a subject of common knowledge among metallurgists. Very little has been published, however, relative to variations existent throughout the cross-sections of rolled strips,1 and the influence that such variations may have. This paper presents such a study on a rolled zinc alloy.2 The significance of small differences in surface structure is shown in relation to bending properties. Experience with zinc and its alloys has shown that the outer radius of the bend, which is subject to tensile deformation, is the common region of failure. In considering relations of structural characteristics to bending properties it will suffice, therefore, to consider the ease and possible extent of tensile deformation resulting from various orientations. It is necessary in this connection to assume that on the average the individual crystals of a polycrystalline material act substantially as if their movements were unobstructed by the surrounding grains. This assumption is not strictly valid, but the error involved is unlikely to affect seriously the qualitative conclusions derived from its use. The mechanism of the plastic deformation of zinc crystals has been described by Mark, Polanyi and Schmid3 and by Mathewson and Phillips,4 and is regarded as ' being accomplished by block movements or