Effects of Sandblasting and Annealing on Surface Recrystallization of DD483 Superalloy

Abstract:

The microstructure evolution and surface recrystallization behavior of sandblasted DD483 Ni-based superalloys after heat treatment around the service temperature were investigated. The specimens of DD483 alloy were sandblasted under the pressure of 0.4~0.7 MPa and annealed at 1100 °C for 4 and 16 h. The results show that the surface of the alloy is effectively cleaned and the compressive stress is introduced into the surface by sandblasting within the range of predetermined sandblasting pressure. After annealing for 4 and 16 h, the Ti and Al elements volatilize to the surface in the form of oxides, and the cellular recrystallization structure appears on the specimen subsurface. The topologically close-packed (TCP) phase and TiN are precipitated in the recrystallized region and the original matrix near recrystallized region, respectively. In addition, the thickness of the recrystallized region is increased with increasing the annealing time and the actual stress.

Key words:Ni-based superalloys;sandblasting;annealing;recrystallization;surface;microstructure