Creep Properties of lnconel-617 in Air and Helium at 800 to 1000°C

Abstract

Creep and structural data are presented on three casts of Inconel alloy 617 tested in air and controlled impurity helium for times up to 42 000 h in a test facility at CIIR, Oslo. Prior cold work reduced initial creep rate at 850°C, but it also reduced the room-temperature tensile ductility measured after samples had been subjected to small creep strains.

The main effect of environment was that air promoted high rupture ductilities, relative to the helium atmosphere used in this work. It was found that air testing caused nucleation and growth of many oxidefilled cracks. Carburization occurred during the helium tests, but this had little influence on rupture life (relative to air tests) under the experimental conditions used here.

Structural examination showed that creep conditions favored the precipitation of carbides on grain boundaries transverse to the imposed tensile stress.