“…Since the first observations of the TRIP effect in metastable austenitic steels [14,15], a large volume of modelling [5-6, 10, 11, 16-18] and experimental work [5,15,16,18,19] has been aimed at understanding the mechanism. During the austenite to martensite transformation, the macroscopic plastic strain, arises from the shape change as determined by the preferential selection of favourable crystallographic variants (Magee effect [9]) and from the plastic accommodation processes which occur around the forming martensite grains (the Greenwood-Johnson effect) [6,12,16,19]. During deformation-induced transformation, two main factors control the plastic flow behaviour of the material: (i) the dynamic softening arising from plastic straining due to the dilation effect upon formation of martensitic grains [11,17] and, (ii) the static hardening caused by the increasing volume fraction of the harder martensitic phase.…”