Superior strength and ductility in a low density duplex steel studied by in situ neutron diffraction

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:799

Article

Magagnosc, Daniel J.¹  Field, Daniel M.¹  Meredith, Christopher S.¹  Walter, Timothy R.¹  Limmer, Krista R.¹  Lloyd, Jeffrey T.¹ 

[1] CCDC Army Res Lab, Weap & Mat Res Directorate, Aberdeen Proving Ground, MD 21005 USA

关键词: Steel;    Neutron diffraction;    Mechanical properties;    Deformation mechanism;   

DOI  :  10.1016/j.msea.2020.140252

来源: Elsevier

【 摘 要 】

A low density, high strength medium-Mn steel was processed to produce a bimodal duplex microstructure consisting of coarse grained gamma-austenite with fine 6-ferrite grains decorating the gamma-austenite boundaries. Using combination of ex situ analysis and in situ neutron diffraction, the deformation mechanisms and lattice strains within each phase were identified for specimens undergoing uniaxial tension during room and elevated temperature loading up to 473 K. The coarse-grained high stacking fault energy gamma-austenite deformed by dislocation glide, providing work hardening and ductility. Simultaneously, the fine grained 6-ferrite produced an elevated yield strength by strengthening the steel via a composite reinforcing mechanism. Neutron diffraction reveals that the yield strength reduction at elevated temperatures is due to a reduction in the 6-ferrite strength. The resulting combination 1200 MPa ultimate strength and 0.3 ductility achieved in this microstructurally engineered bimodal duplex steel exceeds that of typical hot worked medium-Mn steels.

【 授权许可】

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