Direct Observations of Deformation-Induced Retained Austenite Transformation in a Vanadium-Containing Dual-Phase Steel

Transformation-induced plasticity in ferrous alloys

“…Thin-plate martensite has straight interfaces with the adjacent austenite and has a very uniform twinned substructure, where the twins extend across the plate thickness. Plate martensite has been observed as a product phase in steels with a martensitic transformation temperature ðM s Þ below room temperature (Rao and Rashid, 1997;Sugimoto et al, 1997;Christian, 2002). In particular, Sugimoto et al (1997) characterized the microstructures before and after deformation for a TRIP steel with a nominal (average) carbon concentration of 0.2 wt% and with 13 vol% of retained austenite.…”

“…The high yield stress of the austenite has been attributed to a high local carbon concentration. Furthermore, Rao and Rashid (1997) and Sugimoto et al (1997) observed that the ferrite-based matrix sustains severe elastoplastic deformation induced by martensitic transformations. In accordance with these experimental results, we assume that the plastic deformation occurs in the ferrite-based matrix and not in the austenitic parent phase.…”

“…Austenite in carbon steels is a solid phase that usually is unstable at room temperature and zero stress. Nonetheless, with the addition of Si and Al and, under a controlled thermal processing route, it is possible to have regions in which austenite is metastable at room temperature (Rao and Rashid, 1997;Sugimoto et al, 1997;Furne´mont et al, 2002;Zaefferer et al, 2004).…”

Modelling of the effects of grain orientation on transformation-induced plasticity in multiphase carbon steels

“…The parameters for the martensitic transformation model are presented in table 4. The values in this table are representative of an austenite grain with a carbon concentration of 1.4 wt.%, for which the transformation product phase at room temperature is typically a twinned, thin-plate martensite [35,36]. Similarly to the kinetic law of the crystal plasticity model, the parameters for the kinetic law of the transformation model are chosen to reflect a 'weak' rate-dependent transformation behaviour under quasi-static loading conditions.…”

Analysis of banded microstructures in multiphase steels assisted by transformation-induced plasticity

“…A specific class of technologically-important multiphase materials are those assisted by the transformation-induced plasticity mechanism. This class of steels, commonly referred to as TRIP steels, are characterized by a microstructure containing ferrite as the most dominant phase, complemented by retained austenite, bainite, and occasionally a small amount of thermal martensite, see e.g., [1][2][3][4][5][6][7]. The key constituent for steels assisted by transformation-induced plasticity is the retained austenite, which is metastable at room temperature, but may transform into martensite under the application of mechanical and/or thermal loading.…”