Design for creep: A critical examination of some methods

Creep is a slow and continuous plastic deformation of materials over extended periods under a constant load and high temperature [1]. Traditionally creep has been associated with time-dependent plastic deformation at elevated temperatures, often higher than 40% of the material absolute melting temperature, because diffusion can assist creep at elevated temperatures. In this paper, an integrated constitutive model relevant to elastic–plastic–creep interaction is proposed based on the dissipation of the internal strain energy density. The creep failure lives were predicted for a range of applications and compared to the experimental data. The proposed model was compared with several other creep life assessment strategies; in particular the R5 and RCC-MR procedures using creep material properties offered by the European Creep Collaborative Committee (ECCC) and by the National Institute for Materials Science, Materials Database Station (NIMS). The proposed model gives better predictions than the other assessment methods over a range of problems investigated.