Investigation of Rejuvenation of Fatigue Damage in IN-718.
Abstract
This research program investigated the feasibility of rejuvenating the elevated temperature, low cycle fatigue (LCF) properties of a nickel base superalloy, IN-718. The starting material was bar extruded from vacuum-cast billets. The microstructure of the bar was quite heterogeneous, and was not representative of a typical wrought product. The study addressed the rejuvenation of both pre-crack initiation damage, and surface-connected cracks (post-crack initiation damage). The investigation included an evaluation of different surface finishing and coating procedures on simulated crack specimens to assess the most reliable approach for bridging surface-connected cracks. It was found that a combination of shot peening, physical vapor deposition of an IN-718 coating, and a final ceramic coating was able to bridge cracks and provide crack closure and bonding during HIP. Fatigue predamaged bars were given the rejuvenation processing along with undamaged control specimens, and the post-rejuvenation fatigue properties were compared with baseline properties. The results showed that the baseline properties were quite dependent on the rejuvenation process.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1978
- Accession Number
- ADA068333
Entities
People
- Allan H. Clauer
- Brian N. Leis
- David A. Seifert
- G. Hoover
Organizations
- Battelle Memorial Institute