A new theory for the method of X-ray stress measurement with its application to materials having nonlinear sin2{sup left}Ψ diagram

摘要

A new theory of x-ray stress measurement is proposed which is applicable to both isotropic and anisotropic polycrystalline materials. This theory is based only on the fact that the lattice strain or the change Δp in a peak position p of a diffraction line varies in proportion to the stress. Various stresses σ{sub}a were applied to a ψ-split specimen having a nonlinear (sinψ){sup}2 diagram, and a straight line was fitted to n peak positions in the (sinψ){sup}2 diagram for each of the applied stresses. The slope M of the straight line in the (sinψ){sup}2 diagram varies proportionally to the stress σ{sub}a, and the stress constant K can be determined as the reciprocal of the slope of the straight line in M-σ{sub}a diagram. The stress constant K determined from peak positions in the +ψ side agreed with the K from the -ψ side.