A seminumerical method to determine the depth profile of the three dimensional residual stress state with X-ray diffraction

A new method to determine, non-destructively, the full three-dimensional stress stale with depth resolution has been developed. Conventional X-ray residual stress techniques, using different characteristic radiations and several Bragg peaks, are combined with a seminumerical procedure. The analysis incorporates a model function based on the linear theory of elasticity, under consideration of its conditions of equilibrium as well as the surface boundary condition. A least squares fit of a calculated set of peak positions to the experimental data yields the depth dependence of all six components of the stress tenser. This method has been applied to a shot peened work piece, formed from the titanium based alloy Ti-6Al-4V. (C) 1998 Acta Metallurgica Inc.