J. Phys. IV France 07 (1997) C5-459-C5-463
Experimental Characterisation of the Bainitic Transformation Kinetics of Residual Austenite in Mn-Si TRIP-Assisted Multiphase SteelsP. Jacques1, E. Girault2, J. van Humbeeck2, E. Aernoudt2 and F. Delannay1
1 Université Catholique de Louvain, Département des Sciences des Matériaux et des Procédés, PCIM Place Sainte Barbe 2, 1348 Louvain-la-Neuve, Belgium
2 Department of Metallurgy and Materials Engineering, K. U. Leuven, de Croylaan 2, 3001 Leuven, Belgium
Recent studies on TRIP-assisted multiphase steels have emphasised the drastic importance of the bainitic transformation in the optimisation of properties. Bainitic ageing is necessary for the stabilisation of austenite with respect to the martensitic transformation. This metastable retained austenite can still transform to martensite when plastically deformed (TRIP effect). The present work deals with the bainitic reaction kinetics of the austenite obtained by intercritical annealing in two low carbon Mn-Si steels. Bainitic transformation was followed by dilatometry and SEM observations. X-ray diffraction and Mössbauer spectrometry allowed the measurement of the amount of residual austenite and of the carbon enrichment in austenite. The tempering temperature was found to influence the kinetics of austenite transformation and decomposition.
© EDP Sciences 1997