Crystal Plasticity Modeling of Hot Extrusion Texture and Plasticity in a Titanium Alloy for an ICME Toolset

For a better use of titanium alloy in nuclear industry, development of integrated computational materials engineering (ICME) model is necessary to optimize alloy microstructure and thus the performance of titanium component. Within an ICME toolset, constitutive models play an important role in quantitatively capturing the interrelationship between processing, microstructure and property. In this paper, texture evolution during hot extrusion of near-alpha Ti6242S bar were studied with respect to the deformation and transformation texture component. Experimentally measured alpha and beta phase textures were instantiated in a three dimensional rate-dependent crystal plasticity model. The model is able to accurately predict the deformation textures of both the alpha and beta phases at extrusion temperature. While decomposition of the metastable beta phase occurred during the post-extrusion cooling, most of the transformation texture components formed aligned [0001] with the extrusion direction, which formed the primary component of extruded alpha texture. The transformation texture was predicted by numerically decomposing the simulated beta texture according to appropriate variant selection rule. Also demonstrated was the capability of a crystal plasticity model incorporating microstructure information, such as phase fraction and lamellar spacing. The crystal plasticity model was validated by comparing with the experimental elastoplasticity behaviors of Ti6242S bars with various microstructures.