Design of a high strength, high ductility 12 wt% Mn medium manganese steel with hierarchical deformation behaviour

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

卷:782

Article

Kwok, T. W. J.¹  Rahman, K. M.¹  Xu, X.¹  Bantounas, I¹  Kelleher, J. F.²  Daswari, S.³  Alam, T.³  Banerjee, R.³  Dye, D.¹ 

[1] Imperial Coll London, Royal Sch Mines, Dept Mat, Prince Consort Rd, London SW7 2BP, England

[2] Rutherford Appleton Lab, ISIS Neutron & Muon Source, Didcot OX11 0QX, Oxon, England

[3] Univ North Texas, Dept Mat Sci & Engn, 1155 Union Circle 305310, Denton, TX 75203 USA

关键词: Electron microscopy;    Iron alloys;    Plasticity;    Grains and interfaces;    Phase transformation;   

DOI  :  10.1016/j.msea.2020.139258

来源: Elsevier

【 摘 要 】

A novel medium Mn steel of composition Fe-12Mn-4.8Al-2Si-0.32C-0.3V was manufactured with 1.09 GPa yield strength, 1.26 GPa tensile strength and 54% elongation. The thermomechanical process route was designed to be industrially translatable and consists of hot and then warm rolling followed by a 30 min intercritical anneal. The resulting microstructure comprised of coarse elongated austenite grains in the rolling direction surrounded by necklace layers of fine austenite and ferrite grains. The tensile behaviour was investigated by in-situ neutron diffraction and the evolution of microstructure studied with Electron Backscattered Diffraction (EBSD). It was found that the coarse austenite grains contributed to the first stage of strain hardening by transforming into martensite and the fine austenite necklace grains contributed to the second stage of strain hardening by a mixture of twinning and transformation induced plasticity (TWIP and TRIP) mechanisms. This hierarchical deformation behaviour contributed to the exceptional ductility of this steel.

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