Fatigue crack path prediction in Udimet 720 nickel based alloy single crystals


Reed, P.A.S., Wu, X.D. and Sinclair, I. (2000) Fatigue crack path prediction in Udimet 720 nickel based alloy single crystals. Metallurgical and Materials Transactions A, 31, (1), 109-123.

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Description/Abstract

The effect of orientation, applied stress state, environment, and temperature on the crack growth and crack-path behavior of single-crystal specimens of UDIMET 720 has been examined. Stage I cracking has been promoted by mixed-mode loading, plank stress, and vacuum conditions; increasing the test temperature to 600 degrees C does not suppress stage I:crack growth in vacuum. Consideration of the local resolved shear-stress intensity and local resolved normal-stress intensity for each slip system as it intersects the nominal crack-growth plane allows-the prediction of stage I crack paths, clarifying the importance of secondary single-crystal testing orientation (i.e., nominal crack-growth direction as well as effective tensile axis). A combination of both opening and shearing are found to promote stage I crack growth, and boundary conditions,have been established within which stage I cracking is promoted. Highly deflected stage I cracking-gives rise to significant shielding effects, but under suitable mixed-mode loading, highly oriented, coplanar stage I crack growth can be produced. Intrinsic stage I cracking under mixed-mode loading appears to be greatly accelerated compared with mode I-dominated stage II crack growth for comparable stress-intensity levels.

Item Type: Article
ISSNs: 1073-5623 (print)
Related URLs:
Keywords: growth, microstructure, superalloys, propagation, temperature, behavior, fracture, stress
Subjects: T Technology > TN Mining engineering. Metallurgy
Divisions: University Structure - Pre August 2011 > School of Engineering Sciences > Engineering Materials & Surface Engineering
ePrint ID: 43062
Date Deposited: 10 Jan 2007
Last Modified: 27 Mar 2014 18:27
URI: http://eprints.soton.ac.uk/id/eprint/43062

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