Nanoprecipitate-hardened 1.5 GPa steels with unexpected high ductility

We present mechanical and microstructure results on precipitation-hardened ductile high-strength martensitic and austenitic-martensitic steels (up to 1.5 GPa strength) with good ductility. The alloys have a low-carbon content (0.01 wt.% C), 9-12 wt.% Mn, and minor additions of Ni, Ti and Mo (1-2 wt.%). Hardening is based on transformation-induced plasticity and the formation of intermetallic nanoprecipitates in the martensite during heat treatment (aging). The approach leads to an unexpected simultaneous increase in both strength and total elongation. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.