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Fatigue crack initiation and growth in 43Fe-25Ni-22.5Cr austenitic steel at a temperature of 700 °C

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    0492025 - ÚFM 2019 RIV GB eng J - Journal Article
    Mazánová, Veronika - Heczko, Milan - Polák, Jaroslav
    Fatigue crack initiation and growth in 43Fe-25Ni-22.5Cr austenitic steel at a temperature of 700 °C.
    International Journal of Fatigue. Roč. 114, SEP (2018), s. 11-21. ISSN 0142-1123
    R&D Projects: GA MŠk LM2015069; GA MŠk(CZ) LQ1601; GA ČR(CZ) GA13-23652S; GA ČR GA15-08826S; GA MŠk(CZ) EF16_027/0008056
    Institutional support: RVO:68081723
    Keywords : High temperature fatigue * oxidation * crack initiation * crack growth * Sanicro 25
    Subject RIV: JL - Materials Fatigue, Friction Mechanics
    OBOR OECD: Audio engineering, reliability analysis
    Impact factor: 3.673, year: 2018

    Crack initiation and short crack growth in highly-alloyed austenitic steel Sanicro 25 cyclically strained at atemperature of 700 °C has been studied. Specimens cycled to 10% of the fatigue life and to the fracture wereinspected using scanning electron microscopy and electron backscatter diffraction. On the surface, thin lamellaewere extracted site-specifically by focused ion beam and then they were further characterized by high spatialresolution scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. The preferentialoxidation of grain boundaries was found to play a principal role in the initiation of multiple cracks. The oxidescale was analysed to show the distribution of individual elements during crack initiation and growth. Two typesof crack paths were observed: intergranular due to the oxidation and transgranular accompanied by a cyclicplastic zone. Cracks preferentially initiated at the grain boundaries perpendicular to the stress axis and propa-gated in the bulk of the material. The role of the oxidation in high temperature fatigue crack initiation isdiscussed as well as the mechanisms of the crack initiation and growth.
    Permanent Link: http://hdl.handle.net/11104/0288116
     
Number of the records: 1