Correlation of biaxial yield behavior in copper with crystallographic texture for strains in the range 10−4–10−2

Tension-torsion yield surfaces in 101 alloy copper tubing measured at effective strains ranging from 10⁻⁴ to 10⁻² are compared with the predictions from two polycrystalline models: the Bishop-Hill model and a uniform stress lower-bound model. Both models use the crystallite orientation distribution function (CODF) to predict anisotropy in the yield surface. Neither model predicted the yield surface well at an effective strain of 10⁻⁴. At strains above 5×10⁻⁴ both models predict the observed anisotropy between the axial and shear yield stress well. Overall, the lower-bound model prediction was found to exhibit better agreement with the measured yield surface for strains up to 10⁻². Prediction of bulk elastic constants using single crystal compliance values is also discussed. Using the CODF as a weighting factor bulk compliances were predicted to within 4% of the experimental measurements.