Enhanced work-hardening behavior and mechanical properties in ultrafine-grained steels with large-fractioned metastable austenite

Ultrafine-grained duplex manganese-bearing steels fabricated by quenching and annealing demonstrated excellent combinations of tensile elongation of 31-44% and tensile strength of 1-1.5 GPa and a three-stage work-hardening behavior. Their enhanced mechanical properties and work-hardening behavior were explained by their dynamic composition due to the strain induced phase transformation from large-fractioned austenite (>30%). It was suggested that the austenite volume fraction and its mechanical stability is the key to understand the phase transformation induced deformation behavior. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.