On the average internal stresses in each constituent phase in plastically deformed two-ductile-phase alloys

Abstract

The average internal stresses in each constituent phase of plastically deformed α-γ two-ductile-phase FeCrNi steels are studied. Firstly, the average internal stresses produced by the misfit strain between two phases are calculated from a self-consistent continuum model (an unrelaxed model). The effects of the 0.2% proof stress ratio C ∗ (where C ∗ is the 0.2% proof stress of the α phase divided by the 0.2% proof stress of the γ phase) and the volume fraction of the α phase on these stresses are calculated. Secondly, in order to evaluate the influence of plastic relaxation caused by the high local internal stress, these average internal stresses are calculated by an elastic-plastic analysis using the finite element method. The average internal stress is shown to be reduced by the inhomogeneous distribution of plastic strain in each constituent phase After the applied load has been removed, most of the average internal stresses are considered to remain in the specimen. These remaining stresses are called phase stresses or residual stresses. Finally, in order to check the effects of C ∗ and of the α phase volume fraction on the average internal stresses predicted from our calculations, the residual stresses in the α phase were measured using an X-ray technique on the surface of plastically deformed specimens.