Austenite-to-Ferrite Phase Transformation during Continuous Casting of Steels
During the continuous casting process of carbon steels the solidified shell has to
sustain thermal stresses as well as mechanical loading conditions (unbending) when trans-forming
from austenite to ferrite between the Ar3 - and the Ar1 -temperature. Microme-chanical
models have been developed in order to investigate the influence of different g/a
arrangements on the stress/strain situation in the particular composite. When thin ferritic
films surround the inclusion-like austenitic grains a strain concentration has been observed
that gives rise to inter-crystalline fracture. In order to consider microstructural variations,
g-a transformation kinetics is investigated numerically. Carbon diffusion and interface migra-tion,
coupled by appropriate boundary conditions, determine the austenite to ferrite trans-formation.
The results can be plotted in the form of TTT-diagrams. Additionally, a Finite
Element model has been performed in order to investigate the influence of a uniaxially ap-plied
load on the transformation kinetics. This paper presents the results of two years’ work
on micromechanical modelling of the proeutectoid g- a phase transformation.
Ernst GAMSJÄGER, Franz Dieter FISCHER, Christian M. CHIMANI, Jiri SVOBODA
Reçu le 8 août 2001.
Fe-C system, ferrite, austenite, diffusional phase transformation, driving force, kinetics.