Microstructural Evolutions of Superalloy 718 During Dynamic and Metadynamic Recrystallizations

摘要

An investigation of the microstructural evolutions of superalloy 718 was performed. Hot deformation tests were carried out, with and without post deformation holding times, in both uniaxial compression and torsion. The dynamic or metadynamic - most often partially -recrystallized microstructures were characterized using the EBSD technique. In particular, attention was paid to the nucleation of the first recrystallized grains, for which a mechanism similar to continuous dynamic recrystallization was identified, involving a local crystallographic rotation of specific subgrains. The role of twinning, occurring in the necklaces of recrystallized grains by boundary migration, for producing the second and further generations of recrystallized grains, was also dealt with.