Experimental characterization of crack tip deformation fields in Alloy 718 at high temperatures
- Univ. of South Carolina, Columbia, SC (United States)
A series of fracture mechanics tests were conducted at temperatures of 650 C and 704 C in air, using Inconel 719. A noncontacting measurement technique, based on computer vision and digital image correlation, was applied to directly measure surface displacements and strains prior to and during creep crack growth. For the first time, quantitative comparisons at elevated temperatures are presented between experimentally measured near-crack-tip deformation fields and theoretical linear elastic and viscoelastic fracture mechanics solutions. The results establish that linear elastic conditions dominate the near-crack-tip displacements and strains at 650 C during crack growth, and confirm that K{sub 1} is a viable continuum-based fracture parameter for creep crack growth characterization. Postmortem fractographic analyses indicate that grain boundary embrittlement leads to crack extension before a significant amount of creep occurs at this temperature. At higher temperatures, however, no crack growth was observed due to crack tip blunting and concurrent stress reduction after load application.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 634579
- Journal Information:
- Journal of Engineering Materials and Technology, Journal Name: Journal of Engineering Materials and Technology Journal Issue: 1 Vol. 120; ISSN 0094-4289; ISSN JEMTA8
- Country of Publication:
- United States
- Language:
- English
Similar Records
Finite deformation analysis of crack tip opening in elastic-plastic materials and implications for fracture initiation
Large plastic deformation and initiation of fracture at the tip of a crack in plane strain