23 KB926 KB23 KB200020242007Dobina, NataliaGetsov, LeonidRybnikov, Alexandrštevilka:2letnik:416 stranistr. 67-72ISSN:1580-2949COBISSID:602794URN:URN:NBN:SI:doc-VC4OGP3NenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijemehanske lastnostimonokristalinikljeve zlitinesuperzlitinetermična utrujenosttrdnostThermal fatigue of a Ni-based superalloy single crystal| Termična utrujenost monokristala iz nikljeve superzlitine|This paper presents a thermal-mechanical fatigue (TMF) test procedure and some results obtained in vacuum for a Ni-based superalloy single crystal. This procedure allows the monitoring of slip lines, fatigue-crack initiation and propagation until final failure. Single-crystal specimens with different crystallographic orientations were tested under different thermal-cyclic loading conditions. Tests were conducted on smooth specimens as well as on specimens with a central hole of 0.5 mm diameter to analyze the effects of stress concentration. Both crystallographic and non-crystallographic cracks were observed. An increase of the maximum temperature in the cycle (with the same amplitude of temperature change) causes a severe shortening of the service life, as well as stress concentration. It was observed that the first initiated microcrack arrests and the sample fracture takes place on newly nascent microcracksV članku je opisana procedura za določitev termičnega utrujanja (TMF) in nekateri rezultati preizkusov monokristala iz nikljeve superzlitine v vakuumu. Procedura omogoča opazovanje drsnih črt ter začetek in propagacijo razpok do končnega preloma. Monokristali z različno prostorsko orientacijo so bili preizkušani pri različnih pogojih termično ciklične obremenitve. Preizkusi so bili izvršeni na gladkih preizkušancih in na takih s centralno izvrtino s premerom 0,5 mm zaradi analize koncentracije napetosti. Opažene so bile kristalografske in rekristalografske razpoke. Povišanje najvišje temperature v ciklu (pri enakem razponu spremembe temperature) povzroči veliko skrajšanje uporabne dobe, enak je vpliv koncentracije napetosti. Ugotovljeno je bilo, da se prva mikrorazpoka ustavi in da prelom nastane zaradi novo nastalih mikrorazpokTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije