MICROSCOPIC RESIDUAL STRESS IN METALS DEFORMED PLASTICALLY UNDER MULTI-AXIAL STRESS.

The microscopic and macroscopic residual stresses in metals deformed plastically under multi-axial stress are studied with the models of polycrystal. In the analysis, the Taylor model is adopted for the plastic deformation and the uniform stress and uniform strain models are used for the unloading process after the plastic deformation. The state of microscopic residual stress in a grain changes with the orientation of the crystal and it is much affected by the condition of yield stress in the plastic deformation. The microscopic residual stress is different from the macroscopic one. In the case where a compressive residual stress is observed macroscopically, there exists a tensile residual stress in a particular grain. The residual lattice strain is not linearly related to sin**2 psi in x-ray stress measurement. The residual lattice strains measured by x-rays agree with the results analyzed by the Taylor model and the uniform stress model.