LAUSR

Abstract Cyclic softening behavior at elevated temperature of nanolath strengthened steel was rationalized under different strain amplitudes. Results indicated that the evolution of internal stress components and the coarsening of subgrains are significantly depending on the plastic strain level. This paper proposes a dislocation-based viscoplastic constitutive model to represent the cyclic deformation response especially at low plastic strain level. The heterogeneous coarsening of subgrains is explicitly formulated via employing different evolution laws for multiple dislocation populations. An additional back-stress hardening component is introduced to account for the retarded cyclic softening. The cyclic deformation response and microstructural evolution of a nanolath strengthened steel at high/low plastic strain levels are perfectly reproduced.