TRIP: TRansformation Induced Plasticity steel
Definition:TRIP steel is characterized by the martensitic phase transformation during deformation.
Explanation:Conventional TRIP steels are characterized by austenite to α’-martensite phase transformation during deformation. In high Mn steels with the low stacking fault energy (→SFE) (<20 mJ m-2), phase transformation to ε-martensite may occur during deformation [1]. In the perspective of crystallography, the phase transformation to ε-martensite can be explained as the stacking faults (→SFs) taking place on every second close packed plane {111} due to the dissociation of perfect dislocation into partial dislocations, which is mainly controlled by SFE. This mechanical induced phase transformation to ε-martensite strongly affects the mechanical properties of steels, especially strength, ductility, and strain hardening. The main deformation mechanisms for TRIP steel are dislocation slip and deformation induced phase transformation, which result in high strain hardening and delay of necking.
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Fig. 1. ε-martensitic transformation during deformation in a high Mn TRIP steel; the yellow color represents the ε-martensite
SFB-Link:Within SFB761, high Mn TRIP steels are designed and intensively investigated in terms of the microstructure, deformation behavior, ε-martensitic transformation features and mechanisms by means of modeling methods as well as electron backscatter diffraction (→EBSD), transmission electron microscopy, atom probe tomography (→APT) , etc.
References:[1] O. Grässel, L. Krüger, G. Frommeyer, L. W. Meyer. High strength Fe-Mn-(Al, Si) TRIP/TWIP steels development-properties-application. International Journal of Plasticity, 2000, 16: 1391-1409