Fundamental Models for Creep Properties of Steels and Copper

Abstract

New fundamental creep models have been developed based on physical mechanisms. They involve no adjustable (fitting) parameters. This is a good basis for long term extrapolation, which is needed in advanced fossil fired power plants and third and fourth generation nuclear plants. It is demonstrated that the models give sufficiently precise predictions that the results can be applied technically. In the paper, results for austenitic stainless steels and copper are presented. The development of the microstructure is followed during creep. The work hardening and recovery of the dislocation structure are considered as well as the role of the substructure. Nucleation, growth and coarsening of precipitates are taken into account. The influence of substitutional and interstitial elements in solid solution is covered. Nucleation and growth of creep cavities are considered. Properties that have been accurately described include creep rupture strength and creep elongation. The influence of brittle rupture on the creep strength by taking cavitation into account has been analysed.