Residual stress fields in surface treated silicon carbide for space industry comparison of biaxial and triaxial analysis using different X ray methods

Any mechanical surface treatment and machining leaves footprints in form of residual stress fields in the surface region of technical parts or components, which are detectable by X ray diffraction. In the present paper we applied different X ray methods to investigated the residual stress state in the near sur face zone of sintered silicon carbide after mechanical surface processing. Using the sin2y based Univer sal plot method, we found steep gradients for the in plane components s11 and s22 in form of high com pressive stresses at the surface which change into tensile stresses within a few microns. To gain informa tion on the triaxial residual stress state, we applied the scattering vector method, which is based on strain depth profiling by sample rotation around the diffraction vector. For the in plane stresses we observed gradients similar to those obtained by the Universal plot method, but they were shifted on the absolute scale towards tensile stress. We explain this difference by Pseudo macroscopic tensile residual stress fields s33, which act normal to the surface and therefore, pretend higher in plane compressive stresses sii i 1, 2 , if they are not regarded in the evaluation procedur