New view on transformation induced plasticity (TRIP)

The phenomenon of transformation induced plasticity (TRIP) in steel is reinvestigated both experimentally and theoretically. The irreversible length change (TRIP strain) consists not only of a plastic contribution ('Greenwood-Johnson 'effect) but also of a contribution due to the length change caused by the transformation shear component of the martensitic variants (orientation effect or 'Magee' effect). This orientation effect, which is fully accepted for shape memory alloys, is explained for steels. Micromechanical investigations help to quantify the orientation effect. Finally a proposal for a modified constitutive law for elastic plastic phase changing materials is presented.