The nature of the TRIP-effect in metastable austenitic steels

Abstract

Abstract The TRIP-effect in metastable austenitic steels is caused by a moderate local martensitic transformation, influencing both the strain hardening and the damage behaviour. The main conditions of a marked TRIP-effect are a low flow stress in the undeformed state, a high strain hardening exponent, a continuous martensitic transformation up to about 20% and a high resistance to damage (e.g. crack formation and propagation). The martensite transformation starts in glide or shear bands and their intersections even at temperatures clearly above the conventional M d-temperatures, reducing the local stress concentrations and so preventing the onset of damage. Furthermore, high martensite content can be detected along the fracture path impeding the crack propagation by the transformation. To demonstrate the influence of damage on the TRIP-effect the deviations from the so-called Considere-criterion for maximum uniform elongation can be used.