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 〈0 1 1〉 fibre texture continues to evolve. In the compression test, on the other hand, the straining direction is reversed and the fibre texture is transformed into a 〈1 1 1〉 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.