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Title: Fatigue-crack propagation response of two nickel-base alloys in a liquid sodium environment

Conference ·
OSTI ID:6104106

The elevated temperature fatigue-crack propagation response of Inconel 600 and Inconel 718 was characterized within a linear-elastic fracture mechanics framework in air and low-oxygen liquid sodium environments. The crack growth rates of both nickel-base alloys tested in liquid sodium were found to be considerably lower than those obtained in air. This enhanced fatigue resistance in sodium was attributed to the very low oxygen content in the inert sodium environment. Electron fractographic examination of the Inconel 600 and Inconel 718 fatigue fracture surfaces revealed that operative crack growth mechanisms were dependent on the prevailing stress intensity level. Under low growth rate conditions, Inconel 600 and Inconel 718 fracture surfaces exhibited a faceted, crystallographic morphology in both air and sodium environments. In the higher growth rate regime, fatigue striations were observed; however, striations formed in sodium were rather ill-defined. These indistinct striations were attributed to the absence of oxygen in the liquid sodium environment. Striation spacing measurements were found to be in excellent agreement with macroscopic growth rates in both environments.

Research Organization:
Hanford Engineering Development Lab., Richland, WA (USA)
Sponsoring Organization:
USDOE
DOE Contract Number:
EY-76-C-14-2170
OSTI ID:
6104106
Report Number(s):
HEDL-SA-1750; CONF-790615-20; TRN: 79-018463
Resource Relation:
Conference: 3. US national congress on pressure vessels and piping, San Francisco, CA, USA, 25 Jun 1979
Country of Publication:
United States
Language:
English