Browsing by Author "Zrník, J"

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    Deformation behavior of bulk TRIP steel
    (Association for Computational Materials Science and Surface Engineering, 2015-02-02) Zrník, J; Muránsky, O; Novy, Z; Slama, P
    Purpose: Experimental verification of various thermo-mechanical (TM) processing schedules, with aim to modify the structure characteristics using press forging of Si-Mn TRIP (Transformation Induced Plasticity) steel, was described. Design/methodology/approach: High strength and ductility of TRIP steels is attributed to the TRIP effect resulting from the strain induced martensitic transformation of the retained austenite in the multiphase (ferrite, bainite, martensite) microstructure. In order to rationalize the retained austenite (RA) volume fraction in steel microstructure, several TM schedules were employed at experiment where different austenite conditioning was considered. Findings: The various multiphase structure characteristics were then resulting after TM processing of steel, where different volume fractions of ferrite, bainite and RA were received in the steel. The modification of structural characteristics of steel then influenced the deformation behavior and mechanical properties TRIP steel. Research limitations/implications: The present work also focused on monitoring of RA transformation during incremental mechanical straining using in-situ neutron diffraction technique. Originality/value: This non-convenient experimental method was used to characterize the kinetics of RA transformation and its stability during consecutive straining. © 2015 International OCSCO World Press.
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    Impact of microstructure modification on deformation behaviour of bulk TRIP steel
    (Trans Tech Publications Ltd, 2013-04-24) Zrník, J; Muránsky, O; Šittner, P
    The paper presents results of in-situ neutron diffraction experiments aimed on monitoring the phase evolution and load distribution in TRIP steel when subjected to tensile loading. Tensile deformation behaviour of TRIP steel with different initial microstructures showed that the applied tensile load is redistributed at the yield point and the harder retained austenite (Feγ) bears larger load then ferrite (Feα) matrix. After load partioning is finished, macroscopic yielding comes through simultaneous activity of the martensite transformation (in the austenite) and plastic deformation process in ferrite. The steel with higher volume fraction of retained austenite and less stronger ferrite appears to be a better TRIP steel having efficient structure for better plasticity purpose.© 2014 Trans Tech Publications Ltd.