EFFECT OF GRAIN REFINING ON FATIGUE-CREEP INTERACTION BEHAVIOURIN A Ni-BASE SUPERALLOY

The fatigue-creep interaction behaviour of superalloy GH698 with different grain sizes hasbeen studied at 700℃.The results show that three zones,F,C and FC,can be distinguished atthe fatigue-creep interaction curves.In zones FC and C,the presence of alternative stressesinhibits the creep deformation process therefore delays the fracture of the alloy.This effectwill be enhanced by grain refining.However,in zone F,grain refining exhibits an inverse effect under large alternative stresses.