Tensile deformation behavior of superalloy 718 at elevated temperatures

Uniaxial tensile deformation behavior of superalloy 718 at various temperatures and strain rates was studied. The flow stress decreases with increasing temperature and decreasing strain rate. The flow oscillations in stress at lower strain rates are attributed to the occurrence of cyclic dynamic recrystallization (DRX). The activation energy for superalloy 718 under hot tensile deformation is determined to be 450.2 kJ/mol. The undissolved delta phases play an important role in the elongation behavior. The existence of a certain amount of undissolved particle-like delta phases can promote the DRX process as well as suppress the initiation and propagation of grain boundary cracks, leading to the increase of the elongations.