| Abstract |
| In order to characterize the dynamic change of microstructures in commercially-available superalloy 718, a series of compression tests were conducted by varying test temperature and strain rate. Orientation relationship and the misorientations between recrystallized grains as well as unrecrystallized grains were thoroughly investigated with EBSD technique. The dynamically-recrystallized grain size was similar regardless of the compression test condition except for the sample tested at 1066℃-0.005/sec condition, where the dynamically-recrystallized grain size was as large as 20 μm in average diameter. In case of the sample tested at 1066℃, flow stress drops caused by the strain softening were almost same at the strain rates of 0.5/sec and 0.005/sec in spite of the different fraction of dynamic recrystallization. It was concluded from the observation of the misorientation angle distribution that it was due to the active dynamic recovery in the unrecrystallized large grains at high temperature. It was also suggested from the variations of CSL boundary distribution that the characteristic redistribution of the dynamically-recrystallized grain boundary might be taken place during the compression at high temperature and low strain rate. |
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| Key Words |
| Alloy 718, Dynamic recrystallization, Lattice rotation, EBSD, Grain rotation |
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