Over many decades, the creep and creep fracture properties of metals and alloys have commonly been described using power law relationships. However, with this approach, controversies still surround the mechanisms proposed to account for the stress and temperature dependencies of the minimum creep rate and rupture life. Similarly, power law and related expressions do not allow extrapolation of short term data sets to predict the long term properties required for engineering design purposes. For these reasons, over the last 25 years, three UK approaches have evolved, termed the θ projection concept, the hyperbolic tangent method and the Wilshire equations. These methodologies are now applied to results for the aluminium alloy Al 2124, recommending reappraisal of current reliance on power law expressions for theoretical and practical purposes.

 

S. J. Williams¹, M. R. Bache² and B. Wilshire²

1. Rolls-Royce plc, PO box 31, Elton Road, Derby DE24 8BJ, UK
2. Materials Research Centre, School of Engineering, Swansea University, Swansea SA2 8PP, UK

Materials Science and Technology, 26:11, 1332-1337, doi: 10.1179/026708310X12712410311730