Effect of surface recrystallization on the creep rupture properties of a nickel-base single crystal superalloy

The effect of recrystallization on the creep rupture properties of a nickel-base single crystal superalloy has been investigated. It has been found the creep rupture life decreases with increasing of recrystallized depth in the alloy deformed by shot peening. A number of secondary cracks, which link each other and separate the recrystallized region and the matrix, have been observed in the recrystallized alloy after creep rupture. Coarse γ′ precipitations have been found in the interface between the recrystallized grain boundary and the matrix. It pins the crack propagation along the recrystallized grain boundary. Twinning boundary, more stable than high angle grain boundary, is difficult to crack.