Identification of fatigue crack growth mechanisms in IN100 superalloy as a function of temperature and frequency

• Published in: Fatigue & fracture of engineering materials & structures Vol. 36; no. 3; pp. 217 - 227
• Main Authors: ADAIR, B. S., JOHNSON, W. S., ANTOLOVICH, S. D., STAROSELSKY, A.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2013; Blackwell; Wiley Subscription Services, Inc
• Subjects: Applied sciences; Austenitic stainless steels; Crack propagation; Cracks; Ductile brittle transition; Exact sciences and technology; failure mechanisms; Fatigue; fatigue crack growth (FCG); Fatigue failure; Fatigue life; Fracture mechanics; Fracturing; Frequencies; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; polycrystalline superalloy; Scanning electron microscopy; scanning electron microscopy (SEM); stress free activation energy; Superalloys; temperature and frequency effects; Temperature effects; stress free activation energy; Scanning electron microscopy; Temperature; fatigue crack growth (FCG); Temperature effect; Mechanical properties; temperature and frequency effects; Fatigue; Activation; Frequency effect; Free energy; Fatigue crack; Crack propagation; Superalloy; Growth mechanism; failure mechanisms; polycrystalline superalloy; scanning electron microscopy (SEM); Activation energy
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1111/j.1460-2695.2012.01715.x

ABSTRACT A study is undertaken to investigate the fatigue crack growth rate properties of polycrystalline IN100 through the identification of crack growth mechanisms as a function of temperature, frequency and ΔK. An additional goal is to determine the stress free activation energy of IN100. Constant amplitude, load controlled tests are performed at room temperature (22 °C), 316 °C, 482 °C and 649 °C under two different loading frequencies of 20 and 0.33 Hz. These specimens are then analysed via scanning electron microscopy (SEM) to determine failure mechanisms. SEM shows that, as temperature increased from room temperature to 649 °C, the fracture mechanism transitions from transgranular to intergranular. The fracture mechanism is shown to transition from intergranular to transgranular at elevated temperatures as da/dN increases as a result of growing ΔK. Scanning electron microscopy shows that, as frequency decreases from 20 to 0.33 Hz at 649 °C, the fracture mechanism transitions from transgranular to intergranular.