A method for increasing the supersolvus critical strain for recrystallization in single-crystal superalloys

Recrystallization, possibly triggered during heat treatments by plastic strains of only 1-2%, is highly deleterious to Ni-based single-crystal superalloys. Herein, we successfully recover plastic defor-mation and enhance the supersolvus critical strain for recrystallization by ramping the annealing temperature slowly from 1100 degrees C to ?'-solvus point. This preempts recrystallization during the sub-sequent supersolvus solutionizing treatment. The proposed method is validated in single-crystals compressed to 5.9% plastic strain at room temperature. After supersolvus solutionizing, an almost dislocation-free single-crystal with uniformly distributed ?'-precipitates is obtained. The proposed method offers a practical means to bring down the overall expenses of single-crystal turbine blades.

Automated summary

By slowly ramping the annealing temperature to the β-solvus point, plastic deformation can be recovered and the critical strain for recrystallization can be enhanced, thus preventing recrystallization during the subsequent supersolvus solutionizing treatment. The method has been successfully validated in single crystals compressed to 5.9% plastic strain at room temperature. After supersolvus solutionizing, an almost dislocation-free single crystal with uniformly distributed β'-precipitates is obtained. The proposed method offers a practical means to bring down the overall expenses of single crystal turbine blades.