Sin²ψ-based residual stress gradient analysis by energy-dispersive synchrotron diffraction constrained by small gauge volumes. II. Experimental implementation

On the basis of the theoretical concept for the use of small gauge volumes to study near-surface residual stress fields with high spatial resolution [Meixner, Klaus & Genzel (2013). J. Appl. Cryst. 46, 610–618], the experimental implementation of the approach is demonstrated. It is shown that specifically designed slit systems are required to avoid effects such as diffuse scattering at the slit blades and total external reflection, both giving rise to a reduced resolution. Starting from the characterization of the small gauge volume, practical guidance on how to control the alignment of the sample relative to the gauge volume for different geometrical conditions of energy-dispersive diffraction is given. The narrow-slit configuration as well as the formalism for data evaluation introduced in the first part of this series is applied to the analysis of a very steep in-plane residual stress gradient in a shot-peened Al₂O₃ ceramic sample. The results are compared with those obtained by means of a conventional wide-slit setup using the classical universal plot method for residual stress analysis on the one hand, and with the simulations performed in the first part on the other hand.