Microstructural evolution and mechanical behavior of cast alloy 718 during creep-rupture

摘要

Microstructural evolution and mechanical behaviorof cast alloy 718 during creep-rupture were investigated at andabove 650℃. It has been found that deformation twin proceededby the propagation of planar bands at 650℃ , 704℃ and 760℃ . Cracking was initiated along the interfaces between these twinbands and matrix therefore transgranular fracture observed at thetemperature. Creep deformation at and above 704℃ causedprecipitation of plate-like 6 phase along the band. Precipitation ofplate-like 6 phase on the band prevented from transgranularcrystallographic failure, therefore, intergranular creep failure wasobserved at and above 816℃. Due to plastic deformation duringcreep failure at and above 816℃ the δ platelets displayed curvedmorphology at the failed specimens.