Texture induced tension-compression asymmetry of drawn tungsten wires

The stress-strain curves of drawn tungsten wires exhibit a strong tension-compression asymmetry. which is demonstrated experimentally for a series of wires drawn to different diameters. The phenomenon is explained as a consequence of crystallographic texture. Texture evolution is modelled using a visco-plastic self-consistent (VPSC) model. In a tensile test, the straining direction remains the same as during wire drawing, and therefore the (011) fibre texture continues to evolve. In the compression test, oil the other hand, the straining direction is reversed and the fibre texture is transformed into a (111) texture. This is accompanied by transient softening or at least reduced hardening during compression, a prediction which qualitatively agrees with the experiments. The influence of latent hardening on the amount of softening during strain reversal is also investigated.