Mechanical stabilisation of retained austenite in δ-TRIP steel

Recent research suggests that extraordinary combinations of strength and ductility can be achieved in the so-called δ-TRIP steels, which contain ferrite, bainite and austenite. A part of the reason for the ductility of almost 40% elongation at a strength of some 900 MPa, is believed to be the optimal stability of the austenite to plastic deformation. We demonstrate here that mechanical stabilisation plays an important role in preserving the austenite to large plastic strains.

► A new factor controlling the stability of austenite in an important class of steels. ► First observation of the mechanical stabilisation of retained austenite in TRIP steel. ► First observation of severely deformed austenite in TRIP steel. ► First application of an adapted theory for mechanical stabilisation, which at the same time, correlates with mechanical behaviour.