Abstract Scope |
The occurrence of abnormally large overgrown grains upon sub-solvus annealing of certain hot-worked structures has been reported for several cast & wrought and powder metallurgy superalloys. These overgrown grains typically feature a high density of annealing twins and a precipitate distribution similar to the one in the adjacent fine-grained areas. While these special hot working conditions can be established experimentally for a given alloy, it is desirable to provide some general guidance for the avoidance of these features. Following a recently published framework by Bozzolo’s group in France, i.e., Zener pinning pressure versus stored energy driving force, abnormal grain growth (AGG) maps were generated for two commercial HAYNES alloys. Thermo-mechanical processing paths resulting in AGG in these alloys are studied in detail. The generality and limitations of aforementioned framework are discussed. |