J. Phys. IV France 05 (1995) C8-333-C8-338
Stabilization of Austenite Associated with Prior Formation of MartensiteZ.L. Xie1, Y. Liu2 and H. Hänninen1
1 Lab. of Engineering Materials, Helsinki University of Technology, Puumiehenkuja 3A, 02150 Espoo, Finland
2 Dept. MTM, Katholieke Universiteit Leuven, de Croylaan 2, 3001 Heverlee, Belgium
The stabilization of retained austenite was studied via a two-step cooling procedure. Alloys with Ms temperatures below 0 °C were used. It was found that the martensitic transformation starting temperature, Ms, was lowered to Ms' during the second step of cooling. With increasing the amount of previously formed martensite, the difference in the transformation starting temperatures, ΔMs=Ms-Ms'), increases. This stabilization effect can also be observed in an alloy having very low carbon content, and the magnetic properties of alloys do not have drastic effect on the nature of this stabilization phenomenon. The mechanism of the stabilization of retained austenite is proposed to be mainly due to the inhibition effect produced by the previously formed martensite. The aging processes are considered to be a necessary condition for the above mechanism to operate.
© EDP Sciences 1995