In-situ Synchrotron XRD Analysis of the Effect of Static Strain Aging on the Elasto-plastic Transition in CMnSi TRIP Steel

Abstract

In situ synchrotron X-ray diffraction was used to investigate the martensitic transformation kinetics, lattice straining and diffraction peak broadening in cold-rolled TRIP steel during tensile testing. Direct evidence of stress-strain partitioning between different phases, dislocation pinning and differences in yielding behaviour of the different phases were clearly observed. The TRIP steel was subjected to a bake-hardening treatment and a pronounced static strain aging effect was observed. In the present work, the martensitic transformation kinetics and the elastic micro-strain evolution for both ferrite and retained austenite during the elasto-plastic transition are reported with an emphasis on bake-hardening with and without pre-straining.