A Phi-Psi-Diffract (Meter for Residual Stress Measurements

Abstract

AbstractA ϕ-ψ diffractometer has been designed and constructed to evaluate residual stresses in polycrystalline samples by x-ray diffraction. It permits rotations of the x-ray diffraction apparatus, consisting of an x-ray tube and a position-sensitive proportional counter, about two axes ϕ and ψ. The ϕ-rotation from 0° to 360° is carried out about the normal to the surface of the stationary sample, whereas the ψ-motion consists of a rotation from -45° to +45° about an axis lying in the sample surface and the diffraction plane, but perpendicular to the diffraction vector. This ϕ-ψ diffractometer permits the application of the ϕ- and ψ-differential and integral methods for the evaluation of the strain tensor and its gradient averaged over the depth of x-ray penetration into the sample. Assuming that isotropic elasticity theory is applicable, the stress tensor can then be evaluated from the measured strain tensor.