期刊
ACTA MATERIALIA
卷 61, 期 16, 页码 6093-6106出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2013.06.051
关键词
Twinning-induced plasticity steel; In situ neutron diffraction; Twinning; Martensite
资金
- National Natural Science Foundation of China [51231002, 51001024, 50725102]
- Fundamental Research Funds for the Central Universities [N100702001, N100302003]
- National Science and Technology Support Project [2011BAE13B03]
- Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) [20110042120003]
- US National Science Foundation [CMMI-1100080, CMMI-0900271, DMR-0909037]
- US Department of Energy (DOE)
- Office of Nuclear Energy's Nuclear Energy University Program [NEUP-00119262]
- DOE's Office of Fossil Energy, National Energy Technology Laboratory [DE-FE-0008855]
- DOE [DE-AC05-76RL01830]
- DOE's Office of FreedomCAR and Vehicle Technologies under the Automotive Lightweighting Materials Program
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [0909037] Funding Source: National Science Foundation
- Div Of Civil, Mechanical, & Manufact Inn
- Directorate For Engineering [1100080, 0900271] Funding Source: National Science Foundation
The deformation mechanisms and associated microstructure changes during tensile loading of an annealed twinning-induced plasticity steel with chemical composition Fe-20Mn-3Si-3Al-0.045C (wt.%) were systematically investigated using in situ time-of-flight neutron diffraction in combination with post mortem transmission electron microscopy (TEM). The initial microstructure of the investigated alloy consists of equiaxed gamma grains with the initial alpha'-phase of similar to 7% in volume. In addition to dislocation slip, twinning and two types of martensitic transformations from the austenite to alpha'- and epsilon-martensites were observed as the main deformation modes during the tensile deformation. In situ neutron diffraction provides a powerful tool for establishing the deformation mode map for elucidating the role of different deformation modes in different strain regions. The critical stress is 520 MPa for the martensitic transformation from austenite to alpha'-martensite, whereas a higher stress (>600 MPa) is required for actuating the deformation twin and/or the martensitic transformation from austenite to epsilon-martensite. Both epsilon- and alpha'-martensites act as hard phases, whereas mechanical twinning contributes to both the strength and the ductility of the studied steel. TEM observations confirmed that the twinning process was facilitated by the parent grains oriented with < 1 1 1 > or < 1 1 0 > parallel to the loading direction. The nucleation and growth of twins are attributed to the pole and self-generation formation mechanisms, as well as the stair-rod cross-slip mechanism. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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