|About this Abstract
||10th International Symposium on Superalloy 718 and Derivatives (2023)
||Superalloy 718 and Derivatives
||Abnormal Grain Growth Maps of Wrought Ni-base Superalloys
||Michael G. Fahrmann, David Metzler
|On-Site Speaker (Planned)
||Michael G. Fahrmann
Abnormal grain growth (AGG) upon sub-solvus annealing of hot worked material has been reported for a number of cast & wrought and powder metallurgy superalloys, irrespective of the nature of the grain boundary pinning phase (e.g., delta phase in alloy 718 or gamma-prime phase in Rene 88DT). A common feature are large overgrown grains that exhibit the original precipitate distribution as well as a high density of annealing twins (Fig. 1). It has also been established that these phenomena occur only for certain hot working conditions. Identifying these special hot working conditions a priori has proven difficult.
Taking a more industry-oriented approach, we studied the (sub-solvus) annealing response of a sizeable number of hot-worked product forms of two very different wrought Ni-base superalloys: HAYNES 244 alloy and HAYNES 233 alloy. The main grain boundary pinning phase in 244 alloy is an intermetallic Mo-rich phase with a solvus temperature of approximately 2050oF (1120oC). In contrast, the key pinning phase in 233 alloy are secondary Cr- and Mo-rich carbides that precipitate in sufficient quantities below 2100oF (1149oC).
||Definite: At-meeting proceedings