Residual Stress Analysis of Fatigued Austenitic Stainless Steel

The problem of converting of the phase lattice parameters determined by the time-of-flight neutron diffraction measurements in a loaded multiphase system, to strain and subsequently to stress is discussed. An analytical formulation relating the phase applied stress–elastic strain responses in the axial (along the load direction) and transverse directions has been performed which accounts for all the sources of stress measured in the phases. The formulation was applied in the analysis of diffraction spectra from austenitic stainless steel with a martensite phase plastically induced during cyclic tensile-compressive loading. The spectra were obtained during in  situ neutron diffraction stress rig experiments on the ENGIN instrument at the ISIS pulsed neutron facility, subsequent to the cyclic loading. The subsequent applied stress–elastic strain responses of the austenitic matrix and martensitic inclusions were obtained by Rietveld refinement of the spectra, and used to determine the elastic constants and r...