Browsing by Author "Šittner, P"

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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.
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    In situ neutron diffraction investigation of deformation twinning and pseudoelastic-like behaviour of extruded AZ31 magnesium alloy
    (Elsevier, 2009-06) Muránsky, O; Carr, DG; Šittner, P; Oliver, EC
    In situ neutron diffraction has been used to investigate the deformation twinning and untwinning during cyclic uniaxial straining of hydrostatically extruded AZ31 magnesium alloy. The development of the internal stresses and microstructure in the polycrystalline alloy when twinning takes place is explained on the basis of the two pairs of parent {10.0}||, {11.0}|| and twin {00.2}||, {10.3}|| grain families. The experimentally observed pseudoelastic-like behaviour in stress–strain cycles is interpreted as being due to the activation of reversal twinning processes during loading–unloading cycles. It is proposed that the driving force for the observed untwinning is the existence of high tensile stresses in favourably oriented grains which result from significant twinning activity prior to unloading from the peak stress. © 2009, Elsevier Ltd.