Texture Evolution Maps for Upset Deformation of Body-centered Cubic Metals

Abstract

Texture evolution maps are used as a tool to visualize texture development during upset deformation in body-centered cubic metals. These maps reveal initial grain orientations that tend toward normal direction (ND)parallel to < 1 1 1 > versus ND parallel to < 1 0 0 >. To produce these maps, a finite element analysis (FEA) with a rate-dependent crystal plasticity constitutive relation for tantalum is used. A reference case having zero workpiece/die friction shows that similar to 64% of randomly oriented grains rotate toward ND parallel to < 1 1 1 > and similar to 36% rotate toward ND parallel to(10 0). The maps show well-established trends that increasing strain rate sensitivity and decreasing latent-to-self hardening ratio reduce both < 1 1 1 > and < 1 0 0 > percentages, leading to more diffuse textures. Reducing operative slip systems from both {1 1 0}/< 1 1 1 > and {1 1 2}/< 1 1 1 > to just {1 1 0}/< 1 1 1 > has a mixed effect: it increases the < 1 1 1 > percentage but decreases the < 1 0 0 > percentage. Reducing the number of slip systems and increasing the number of FEA integration points per grain strengthen < 1 1 1 >-< 1 0 0 > texture bands that are observed experimentally. (c) 2007 Elsevier B.V. All rights reserved.