Relationship between Grain Size and Fatigue-Creep Interaction Behaviour of Superalloy GH698

The deformation and fracture behaviourof nickel-base superalloy GH698 with differentgrain size have been studied at 700℃ underfatigue-creep interaction conditions. Comparedwith coarse-grained specimens, the grain refiningprocess shows obvious effect on the mechanicalbehaviour of the alloy, i. e. in F and C zones,the fraction of pure fatigue and creep fractureon fracture surfaces is greatly reduced, whichdecreases and increases the fracture life inzones F and C respectively, in FC and C zones,creep deformation is greatly restrained by thealternating stress component, which increasesthe fracture life remarkably. It is also provedthat in spite of the difference in microstru-tures such as grain size, for a constant tem-perature, a unique life equation t_r=A~n canbe used to predict rupture life within the stressregion controlled by the same fracture mode.

Relationship between Grain Size and Fatigue-Creep Interaction Behaviour of Superalloy GH698

The deformation and fracture behaviour of nickel-base superalloy GH698 with different grain size have been studied at 700℃ under fatigue-creep interaction conditions. Compared with coarse-grained specimens, the grain refining process shows obvious effect on the mechanical behaviour of the alloy, i. e. in F and C zones, the fraction of pure fatigue and creep fracture on fracture surfaces is greatly reduced, which decreases and increases the fracture life in zones F and C respectively, in FC and C zones, creep deformation is greatly restrained by the alternating stress component, which increases the fracture life remarkably. It is also proved that in spite of the difference in microstru- tures such as grain size, for a constant tem- perature, a unique life equation t_r=A~n can be used to predict rupture life within the stress region controlled by the same fracture mode.