Effect Of Recrystallization On Axial High Cycle Fatigue Properties Of Dd6 Single Crystal Superalloy

In order to study the effect of recrystallization on the high cycle fatigue (HCF) properties of DD6 single crystal superalloy, the specimens of DD6 alloy after standard heat treatment were grit blasted and heat treated at 1120 degrees C and 1315 degrees C for 4h at vacuum atmosphere, respectively. Axial HCF tests on both raw and recrystallized samples were carried out, and then the recrystallization microstructures and fatigue fracture morphology of DD6 alloy were observed by SEM. The results show that cellular recrystallization and equiaxed recrystallization reduce the axial HCF properties of the alloy, and the effect of cellular recrystallization on the axial HCF properties is less than that of the equiaxed recrystallization. The axial HCF fracture mechanism of DD6 alloy with recrystallization is the maxed fracture of dimple fracture distributed in interdendritic region and cleavage-like fracture. Also, it is emphasized that DD6 alloy with recrystallization is a multiple fatigue crack initiation mechanism. Under high temperature conditions, the presence of recrystallization significantly promotes oxidative damage of alloy specimens, thereby accelerating the earlier crack initiation and propagation, which is responsible for fatigue degradation.