[Back]

B. Viernstein, E. Kozeschnik:
"Computational analysis of deformation maps";
Talk: MEFORM 2020, Freiberg; 2021-03-18 - 2021-03-19; in: "The Metal Forming Conference MEFORM 2020", TU Bergakademie Freiberg, (2021), ISBN: 978-3-86012-632-5; 34 - 36.

A fundamental understanding of the underlying deformation mechanisms is essential to simulate macroscopic stress-strain relations. Plastic strain is caused either by dislocation glide and climb or a stress-directed flow of vacancies. Since diffusion is a thermally activated process, the creep behavior of polycrystalline materials strongly depends on the applied stresses and temperatures. For simulating secondary creep rates, microstructural characterization is mandatory. The steady-state microstructure during secondary creep provides barriers for ongoing dislocation movement on the one hand, and the acceleration of diffusion along grain boundaries and dislocations on the other hand. In the present manuscript, various creep mechanisms are discussed. Implementation of the mechanical threshold concept, as well as the power law and diffusional flow regimes, which are dominant at lower applied stresses, are introduced. Deformation maps of pure aluminum are plotted for different grain sizes, including dislocation glide, low temperature creep (L.T. creep), high temperature creep (H.T. creep), Coble creep (C. creep), Nabarro Herring creep (N.H. creep) and Harper Dorn creep (H.D. creep). Furthermore, power law breakdown at high stresses is phenomenologically described and is included within in the simulations.

Dislocation glide; Dislocation climb; Diffusional creep; Deformation maps