Influence of trace elements on creep and stress-rupture properties of Nimonic 105

Abstract

The effects of trace amounts of Pb, Sn, Se, Te, and Tl on the creep and stressrupture properties of Nimonic 105 at 815°C have been investigated. The work confirmed that with the exception of Sn, all the elements have a deleterious effect when present in a sufficient amount. The most harmful impurities were Te and Pb. A generally more sensitive indication of the presence of harmful amounts of impurity was obtained with notched specimens. Optical metallography established that the deleterious effects were associated with greatly increased intergranular cavitation which became evident at an early stage of creep life when impurities were present. Auger electron spectroscopy showed that about one monolayer of lead was present on a cavitated grain boundary in a creep-tested specimen containing 34 ppm of Pb.