EVOLUTION OF ANISOTROPY UNDER PLANE-STRESS

Yield loci have been measured for cold rolled steel sheets prestrained by two stage loading. During the first loading, the sheets have been stretched by 3 and 6% tensile strain in the rolling direction. The sec ond loading was at angles to the rolling direction with varying amount s of tensile strain. Then a set of tensile test specimens has been pre pared from each of the prestrained sheets. From tensile tests, effects of the two-stage prestrains on the subsequent yielding has been inves tigated. Experiments show that initial orthotropic symmetry is maintai ned and that the orientations of orthotropy axes change continuously t hroughout the prestraining process. A simple phenomenological rule for the rotation of orthotropy axes is suggested. (C) 1997 Elsevier Scien ce Ltd.