Fatigue Crack Growth Mechanisms for Nickel-based Superalloy Haynes 282 at 550-750 °C

Autor:	John S. Sears, Jamie J. Kruzic, Kyle A. Rozman, Jeffrey A. Hawk
Rok vydání:	2015
Předmět:	Materials science Mechanical Engineering Metallurgy chemistry.chemical_element Activation energy Paris' law Superalloy Nickel Crack closure chemistry Creep Mechanics of Materials General Materials Science Dislocation Softening
Zdroj:	Journal of Materials Engineering and Performance. 24:3699-3707
ISSN:	1544-1024 1059-9495
DOI:	10.1007/s11665-015-1678-8
Popis:	The fatigue crack growth rates for nickel-based superalloy Haynes 282 were measured at 550, 650, and 750 C using compact tension specimens with a load ratio of 0.1 and cyclic loading frequencies of 25 and 0.25 Hz. The crack path was observed to be primarily transgranular for all temperatures, and the observed effect of increasing temperature was to increase the fatigue crack growth rates. The activation energy associated with the increasing crack growth rates over these three temperatures was calculated less than 60 kJ/mol, which is significantly lower than typical creep or oxidation mechanisms; therefore, creep and oxidation cannot explain the increase in fatigue crack growth rates. Transmission electron microscopy was done on selected samples removed from the cyclic plastic zone, and a trend of decreasing dislocation density was observed with increasing temperature. Accordingly, the trend of increasing crack growth rates with increasing temperature was attributed to softening associated with thermally assisted cross slip and dislocation annihilation.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::d7f88f4bea267e2f1fdf62ac5302afae https://doi.org/10.1007/s11665-015-1678-8 Zobrazit plný text záznamu Full text from SpringerLink