A computational micromechanics study of stress-assisted martensitic transformation using finite elements is carried out within a thermomechanical framework including the aspect of plastic deformation. The phase transformation is treated by a stress-free transformation tensor corresponding to a certain habit plane variant involving a shape change resulting from shear and dilatational deformations which are eigenstrains within the emerging martensitic phase. General plane strain and axisymmetric analyses are carried out introducing different micromechanical models with appropriate boundary conditions required for the microfield approach. The introduced models are compared with a micromechanical model developed by Tvergaard in the viewpoint of thermodynamic aspects concerning the formation of martensite. The representative volume elements are specified with respect to the Schmid factor for the transformation shear corresponding to an average crystallographic orientation of a grain. We examine elastic-plastic deformations and distribution of transformation-induced microstress fields in both the parent and the emerging product phase due to accommodation of the transformation shape change. Analytical results for the linear elastic case based upon the Eshelby approach will be compared with numerical results. The plastic behavior of austenitic and martensitic microconstituents is described in the context of J2-flow theory with isotropic hardening. The thermomechanical framework is based on an explicit form of a potential suggesting the form of Gibbs free energy, from which transformation conditions on the mesodomain-, interface- and nucleation-site level are derived. The arrangement of martensitic microregions transforming in a stress field is studied considering the thermomechanical coupling of orientation and accommodation effects.
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