Strain localization and fatigue crack initiation in ultrafine-grained copper in high- and giga-cycle region

0434886 - ÚFM 2015 RIV GB eng J - Článek v odborném periodiku
Kunz, Ludvík - Lukáš, Petr - Navrátilová, L.
Strain localization and fatigue crack initiation in ultrafine-grained copper in high- and giga-cycle region.
International Journal of Fatigue. Roč. 58, JAN (2014), s. 202-208. ISSN 0142-1123. E-ISSN 1879-3452
Grant CEP: GA ČR GAP108/10/2001; GA MŠMT(CZ) ED1.1.00/02.0068
Institucionální podpora: RVO:68081723
Klíčová slova: Fatigue crack initiation * Strain localization * Stability of ultrafine-grained structure * UFG Cu
Kód oboru RIV: JL - Únava materiálu a lomová mechanika
Impakt faktor: 2.275, rok: 2014

Initiation of fatigue cracks and early crack propagation in high-cycle and giga-cycle region in ultrafine-grained copper prepared by equal channel angular pressing was experimentally investigated. The cyclic slip localization takes place in cyclic slip bands whose length substantially exceeds the grain size. The mechanism of the crack initiation under load controlled cycling does not require the dynamic grain coarsening often indicated in literature. Fatigue cracks initiate in slip bands, which develop predominantly in zones of near-by oriented grains. The damage mechanism consists in localized slip resulting in development of cavities and voids arranged along the planes of highest cyclic shear stress and in formation of surface relief. A process of growth and linking of cavities and voids produced by the irreversible cyclic slip by dislocation movement generating point defects governs the early stage of the development of fatigue cracks. Sufficiently large cracks created by this mechanism and lying in suitably oriented long slip bands finally transform into fatigue cracks propagating by common opening mode with a plastic zone generated at their tip. 2013 Elsevier Ltd. All rights reserved.
Trvalý link: http://hdl.handle.net/11104/0238861