Recovery of creep properties of the nickel-base superalloy nimonic 105

Abstract

Uniaxial constant stress creep tests were performed on the wrought nickel-base superalloy Nimonic 105. Entire creep curves were recorded and curve shapes analysed using the Theta Projection Concept. Rejuventive procedures were applied to pre-crept samples and creep recovery quantitatively assessed. Microstructural damage occurring during the creep of Nimonic 105 was studied. Creep strength is lost by the coarsening of the precipitate and grain boundary carbides. The Theta Projection Concept relates damage to strain using a Kachanov model. Damage accumulation can be measured and any rejuvenation procedure can be assessed for effectiveness by curve shape analysis. It is found that complete re-solution heat treatment is able to recover the microstructure and, on re-testing, significant creep curve recovery is observed. An additional heat treatment was performed under hydrostatic pressure of 100MPa in argon to remove cavities. Complete recovery of the creep curve was achieved even when this procedure was applied late in the tertiary stage of creep.