Effect of Temperature on the Lattice Strain Evolution in a Textured Alpha Titanium: Neutron Diffraction and Modelling

Plastic deformation of titanium alloys depends on the temperature and the mechanical loading mode. It is accommodated by a complex mixture of slip and twinning systems. It remains nevertheless unclear which deformation modes are activated in the polycrystal during loading, especially with the temperature. To better understand the mechanical behaviour of textured α-Ti, neutron diffraction measurements have been performed to analyse the intergranular strain evolution under tensile tests at different temperatures ranging from ambient up to 300 °C. The material has then been characterized from meso- (grain) to macroscopic scales to obtain relevant information about the deformation mechanisms governing its global behaviour. An elastoplastic self-consistent approach has been used to explain and interpret the experimental observations achieved under thermomechanical loadings. The model has enabled us to successfully predict the measured macroscopic behaviour and lattice strain development. The study has also provided a comprehensive data set and a complete description of temperature influence onto the mechanical state and the plastic anisotropy, especially at the mesoscopic level. The evolutions of the deformation mode hierarchy and the internal stress fields with the temperature have been determined.