abstract
TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS. (C) 2015 Elsevier B.V. All rights reserved.
keywords
AUSTENITIC STEEL; DEFORMATION; MECHANISMS; ALLOYS; MODEL; GRAIN
subject category
Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering
authors
Bintu, A; Vincze, G; Picu, CR; Lopes, AB; Gracio, JJ; Barlat, F
our authors
Alexandra Bintu
Research Fellowship
Augusto Luís Barros Lopes
Assistant Professoracknowledgements
This research has been funded by Portuguese Foundation of Science and Technology (FCT) through Project PTDC/EME-PME/116683/2010, the support of which the authors are gratefully acknowledged. Special thanks are given to POSCO (South Korea) for providing the studied material.