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Fatigue Crack Initiation in Nickel-Based Superalloy MAR-M247 at High Temperature
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SYSNO ASEP 0478819 Document Type C - Proceedings Paper (int. conf.) R&D Document Type Conference Paper Title Fatigue Crack Initiation in Nickel-Based Superalloy MAR-M247 at High Temperature Author(s) Šulák, Ivo (UFM-A) ORCID
Obrtlík, Karel (UFM-A) RID, ORCIDNumber of authors 2 Source Title Advances in Fracture and Damage Mechanics XVI. - Zurich : Trans Tech Publications Ltd, 2017 / Mariano P. M. ; Baragetti S. ; Casavola K. ; Pappalettere C. ; Aliabadi F. M. H. - ISSN 1662-9795 - ISBN 978-3-0357-1168-4 Pages s. 27-30 Number of pages 4 s. Publication form Print - P Action FDM 2017 International Conference on Fracture and Damage Mechanics /16./ Event date 18.07.2017 - 20.07.2017 VEvent location Florence Country IT - Italy Event type WRD Language eng - English Country CH - Switzerland Keywords Fatigue crack initiation ; Focus ion beam ; MAR-M247 ; Surface relief Subject RIV JL - Materials Fatigue, Friction Mechanics OECD category Audio engineering, reliability analysis R&D Projects GA15-20991S GA ČR - Czech Science Foundation (CSF) Institutional support UFM-A - RVO:68081723 EID SCOPUS 85029908016 DOI 10.4028/www.scientific.net/KEM.754.27 Annotation The present work is focused on the study of crack initiation during low cycle fatigue (LCF) loading of the second generation nickel-based superalloy MAR-M247 treated with hot isostatic pressing. LCF tests were conducted on cylindrical specimens in symmetrical push-pull cycle under strain control with constant total strain amplitude and strain rate at 800 °C in air atmosphere. Selected specimens were electrolytically polished to facilitate surface relief observations. Crack initiation sites were studied by means of scanning electron microscopy (SEM) in dual beam microscope TESCAN LYRA 3 XMU FESEM equipped with focus ion beam (FIB). The microstructure of the material is characterised by coarse dendritic grains with numerous carbides and small casting defects. The average grain size was 2.1 ± 0.3 mm. Fractographic analysis revealed the fatigue crack initiation sites and their relation to the casting defects and material microstructure. Casting defects, carbide inclusions and interdendritic areas were found to be important crack nucleation sites. Specimens’ surface observations revealed the formation of pronounced surface relief with short worm-like markings. Fatigue crack initiation in these places is documented and discussed. Workplace Institute of Physics of Materials Contact Yvonna Šrámková, sramkova@ipm.cz, Tel.: 532 290 485 Year of Publishing 2018
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