A novel approach for nondestructive depth-resolved analysis of residual stress and grain interaction in the near-surface zone applied to an austenitic stainless steel sample subjected to mechanical polishing
Marianna Marciszko‐Wiąckowska, Adrian Oponowicz, A. Baczmański, Ch. Braham, M. Wątroba, Mirosław Wróbel, M. Klaus, Ch. Genzel
Abstract
The choice of the grain interaction model is a critical element of residual stress analysis using diffraction methods. For the near-surface region of a mechanically polished austenitic steel, it is shown that the application of the widely used Eshelby-Kröner model does not lead to a satisfactory agreement with experimental observations. Therefore, a new grain interaction model called 'tunable free-surface' is proposed, allowing for the determination of the in-depth evolution of the elastic interaction between grains. It has a strong physical justification and is adjusted to experimental data using three complementary verification methods. It is shown that a significant relaxation of the intergranular stresses perpendicular to the sample surface occurs in the subsurface layer having a thickness comparable with the average size of the grain. Using the new type of X-ray Stress Factors, the in-depth evolution (up to the depth of 45 μm) of residual stresses and of the strain-free lattice parameter is determined.