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Dwell notch low cycle fatigue behavior of a powder metallurgy nickel disk alloy
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Yamada, Y. Ghosn, L. J. Jayaraman, N. Telesman, J. Gabb, T. P. |
| Copyright Year | 2012 |
| Description | A study was conducted to determine the processes which govern dwell notch low cycle fatigue (NLCF) behavior of a powder metallurgy (P/M) ME3 disk superalloy. The emphasis was placed on the environmentally driven mechanisms which may embrittle the highly stressed notch surface regions and reduce NLCF life. In conjunction with the environmentally driven notch surface degradation processes, the visco-plastic driven mechanisms which can significantly change the notch root stresses were also considered. Dwell notch low cycle fatigue testing was performed in air and vacuum on a ME3 P/M disk alloy specimens heat treated using either a fast or a slow cooling rate from the solutioning treatment. It was shown that dwells at the minimum stress typically produced a greater life debit than the dwells applied at the maximum stress, especially for the slow cooled heat treatment. Two different environmentally driven failure mechanisms were identified as the root cause of early crack initiation in the min dwell tests. Both of these failure mechanisms produced mostly a transgranular crack initiation failure mode and yet still resulted in low NLCF fatigue lives. The lack of stress relaxation during the min dwell tests produced higher notch root stresses which caused early crack initiation and premature failure when combined with the environmentally driven surface degradation mechanisms. The importance of environmental degradation mechanisms was further highlighted by vacuum dwell NLCF tests which resulted in considerably longer NLCF lives, especially for the min dwell tests. |
| File Size | 4451954 |
| Page Count | 18 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20130000793 |
| Archival Resource Key | ark:/13960/t06x4bs0x |
| Language | English |
| Publisher Date | 2012-12-01 |
| Access Restriction | Open |
| Subject Keyword | Metals And Metallic Materials Nickel Alloys Notches Dwell Waveforms High Temperature Powder Metallurgy Finite Element Method Degradation Fatigue Tests Vacuum Heat Resistant Alloys Oxidation Failure Crack Initiation Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
