Isao Gokyu1 and Keijiro Suzuki1
1Department of Metallurgy, Faculty of Engineering, The University of Tokyo, Tokyo
It has previously been shown that the plastic anisotropy of metals as measured by the ratio R of width strain to thickness strain in a tension test correlates generally with crystallographic orientation as determined by X-ray pole figures. It is possible to predict the R ratio through theoretical treatment of orientation.
Burns and Heyer calculated theoretical ratio of width strain to thickness strain for two specific orientations of the b.c.c. system, using < 111> as the operative slip direction. These calculated values were in fairly good agreement with the ratios determined by tension test of low-carbon steel in which these preferred orientation existed. But we are doubtful to test strictly the relation between the R ratio and the texture for low-carbon steel with less preferred orientation.
So we used the copper sheets having very sharp (001) recrystallization texture to verify the validity of the proposed orientation. We determined R ratio in the tensile specimens taken from the cubic texture sheet cut at 0°, 15°, 30°, 45°, 60°, 75° and 90° to the rolling direction. We obtained following results, (1) The calculated value is in very good agreement with measured R ratio. The R value is dependent on the crystallographic anisotropy of metals. (2) The tensile deformation of specimen cut 45° to the rolling direction can be explain to proceed by the slip on the slip systems act (1 1) and (1 1)[ 01] simultaneously. These systems act co-operatively as if they were the simple slip system (1 1)[ 12].
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