Theoretical and practical approaches to creep of Waspaloy

Abstract

After normalising the applied stress through the ultimate tensile strength at each creep temperature, the creep and creep fracture properties of Waspaloy at 873 to 1023 K are superimposed onto ‘master curves’ using an Arrhenius term containing the activation energy for lattice diffusion in the nickel alloy matrix (∼276 kJ mol⁻¹). In this way, straightforward approaches are introduced for extrapolation of short term property sets, aiming to minimise the scale of the protracted test programmes currently needed to provide long term engineering design data. The observed behaviour patterns are then interpreted by clarifying the deformation and damage processes governing the changing shapes of the creep strain–time curves exhibited as the test conditions are varied.