Hot working characteristics and dynamic recrystallization of delta-processed superalloy 718

Hot working characteristics and microstructural mechanisms of delta-processed superalloy 718 at various temperatures and strain rates were studied using the processing maps. The results show that there are two domains of dynamic recrystallization (DRX) exhibited in the map: one occurring around 1050 degrees C and 0.001 s(-1) with a peak efficiency of 54%, and the other at 1000 degrees C and 0.01 s(-1) with a peak efficiency of 46%. The behavior of the pre-precipitated delta phases during hot working has a great effect on the DRX of delta-processed superalloy 718. The flow instability at the strain rates higher than 0.4 s(-1) is suggested to be associated with the inconsistent deformation due to the existence of the undissolved short needle-shaped delta phases. (C) 2008 Elsevier B.V. All rights reserved.