A model for transformation plasticity during bainite transformation of steel under external stress

A model, which can calculate the transformation strain components when steel transforms to bainite under an external stress, is suggested. In the model, the change of the nucleation rate for each variant due to the applied stress during transformation is considered. To assess the difference of the nucleation rate for variants, the interaction energy between the lattice deformation of the variant and the externally applied stress is calculated on the basis of Kurdjumov-Sachs (KS) orientation relationship. From the model, both the volumetric and deviatoric strains caused by bainite transformation can be simultaneously obtained. The calculation results are compared with the experimental dilatometric measurements under various uniaxial compressive stresses. Good agreement is found between the calculated and experimental values of transformation strain.