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Temperature dependent cyclic deformation mechanisms in haynes 188 superalloy
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Castelli, Michael G. Allen, Gorden P. Ellis, John R. Rao, K. Bhanu Sankara |
| Copyright Year | 1995 |
| Description | The cyclic deformation behavior of a wrought cobalt-base superalloy, Haynes 188, has been investigated over a range of temperatures between 25 and 1000 C under isothermal and in-phase thermomechanical fatigue (TMF) conditions. Constant mechanical strain rates (epsilon-dot) of 10(exp -3)/s and 10(exp -4)/s were examined with a fully reversed strain range of 0.8%. Particular attention was given to the effects of dynamic strain aging (DSA) on the stress-strain response and low cycle fatigue life. A correlation between cyclic deformation behavior and microstructural substructure was made through detailed transmission electron microscopy. Although DSA was found to occur over a wide temperature range between approximately 300 and 750 C the microstructural characteristics and the deformation mechanisms responsible for DSA varied considerably and were dependent upon temperature. In general, the operation of DSA processes led to a maximum of the cyclic stress amplitude at 650 C and was accompanied by pronounced planar slip, relatively high dislocation density, and the generation of stacking faults. DSA was evidenced through a combination of phenomena, including serrated yielding, an inverse dependence of the maximum cyclic hardening with epsilon-dot, and an instantaneous inverse epsilon-dot sensitivity verified by specialized epsilon-dot -change tests. The TMF cyclic hardening behavior of the alloy appeared to be dictated by the substructural changes occuring at the maximum temperature in the TMF cycle. |
| File Size | 6190638 |
| Page Count | 13 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19960007619 |
| Archival Resource Key | ark:/13960/t9673cs11 |
| Language | English |
| Publisher Date | 1995-08-03 |
| Access Restriction | Open |
| Subject Keyword | Structural Mechanics Metal Fatigue Temperature Dependence Fatigue Life Crystal Defects Tensile Deformation Cyclic Loads Thermal Cycling Tests Precipitation Hardening Wrought Alloys Thermodynamics Transmission Electron Microscopy Stress-strain Relationships Heat Resistant Alloys Microstructure Cobalt Alloys Strain Rate Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
