X-RAY ANALYSIS OF STEEP NEAR-SURFACE RESIDUAL STRESS GRADIENTS

摘要

Advanced procedures, based on the use of a seminumerical method to determine the depth profile of residual stress states is presented. This method requires fitting the experimentally determined peak positions to a set determined from a numerical model which does not rely on a priori information of the state of the sample, but which does make full use of the linear theory of elasticity. The procedure has been applied to a ground Al_2O_3 based composite ceramic, with expected steep stress gradients in the near surface region. The principal stresses σ_(11) and σ_(22) have a similar depth distribution and surface value between 2 and 3 GPa, whereas the shear component is negligibly small, confirming that the principal axes of the biaxial surface stress state are parallel and perpendicular to the grinding direction. This constraint was, however, not included in the model function.