OBSERVATIONS AND CALCULATIONS ON MECHANICAL ANISOTROPY AND PLASTIC-FLOW OF AN ALZNMG EXTRUSION

An extruded plate of the alloy AA7108 has been characterized using tex ture analysis and uniaxial tensile tests. The yield surface, direction al yield stresses and plastic strain ratios are calculated from Taylor -Bishop-Hill analysis, employing the measured texture data in combinat ion with either the full constraints model or a relaxed constraints mo del. Three phenomenological yield functions, capable of describing yie ld anisotropy, are compared by means of their ability to reproduce the shape of the crystallographic yield surface and to predict directiona l properties, i.e. R-values and yield stress. On the basis of experime nts and calculations it has been found that the Taylor relaxed constra ints model describes the present material more consistently with respe ct to experimental findings than the Taylor full constraints model. Co pyright (C) 1996 Acta Metallurgica Inc.