Revealing the role of dislocations on the stability of retained austenite in a tempered bainite

摘要

The present study, for the first time, provides direct experimental evidence revealing the effect of dislocations of the bainite matrix on the mechanical stability of retained austenite (RA) in a low carbon bainitic steel, while keeping all other influencing factors unchanged. A lower strength of bainitic matrix caused by its reduced dislocation density results in more stress partitioning onto RA during plastic deformation, which promotes the transformation of RA to martensite. In addition, the annihilation of dislocations in the bainite matrix relaxes the compressive stress field resulted from the bainitic transformation, facilitating the martensitic transformation during deformation. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.