Effect of Grain Refinement on the Mechanical Behaviour of Ferritic Steels: Evolution of Isotropic Hardening and Kinematic Hardening

New experimental data related to the grain size and the Bauschinger effects have been obtained for ferritic steels with grain size in the range of 3.5-22m. As the data show an increasing contribution of the kinematic hardening with grain size refinement, a new physical based model describing the isotropic hardening and the kinematic hardening is presented and validated with regard to the grain size. The consequences are discussed for fine grain metallic alloys.