Plastic flow during equal-channel angular pressing with arbitrary tool angles

Wagner, M. F.-X.; Nostitz, N.; Frint, S.; Frint, P.; Ihlemann, J.

doi:10.1016/j.ijplas.2020.102755

Plastic flow during equal-channel angular pressing with arbitrary tool angles (bibtex)

by M. F.-X. Wagner, N. Nostitz, S. Frint, P. Frint, J. Ihlemann

Abstract:

Equal-channel angular pressing (ECAP) allows to rapidly accumulate massive amounts of plastic strain and thus to promote grain refinement in metals, which is one of the main goals of severe plastic deformation methods. While early models have simplified the deformation during ECAP as simple shear, experimental observations and numerical simulations of fan-shaped deformation regions have motivated more elaborate analytical models that explicitly consider material flow through the region of most intense plastic straining. The two most prominent models (Beyerlein and Tomé, 2004), and (Tóth, 2003), allow to successfully predict texture evolution during ECAP, but their most basic versions have originally been limited to 90° ECAP tools. In this contribution, both models are extended to provide a detailed analysis of ECAP tools with arbitrary tool angles (in the practically relevant range from 90° up to 180°) that allows to fully describe novel developments in tool design. Most importantly, it is shown that a single free parameter is sufficient to modify the shape of the plastic deformation region, maintaining the simplicity of the corresponding original models. Explicit solutions are given in terms of strain rates and, by integration along a flow line, for strain tensor components, for equivalent strains per ECAP pass and for deformation gradients. The corresponding strain states predicted by both models are directly compared for arbitrary tool angles. It is further demonstrated that both models lead to similar strains in the two relevant limiting cases. Finally, exemplary fitting of experimental flow line data from Cu billets deformed in 90° and 120° tools allows for direct validation of the extended version of Tóth's model, demonstrating that it provides a sound basis for an in-depth experimental and theoretical analysis of plastic straining during ECAP in different tools and with varying processing parameters.

Reference:

Wagner, M. F.-X., Nostitz, N., Frint, S., Frint, P., Ihlemann, J.: Plastic flow during equal-channel angular pressing with arbitrary tool angles, International Journal of Plasticity 134, 102755, 2020.

Bibtex Entry:

@Article{Wagner2020,
  author    = {Wagner, M. F.-X. and Nostitz, N. and Frint, S. and Frint, P. and Ihlemann, J.},
  journal   = {International Journal of Plasticity},
  title     = {Plastic flow during equal-channel angular pressing with arbitrary tool angles},
  year      = {2020},
  month     = {nov},
  pages     = {102755},
  volume    = {134},
  abstract  = {Equal-channel angular pressing (ECAP) allows to rapidly accumulate massive amounts of plastic strain and thus to promote grain refinement in metals, which is one of the main goals of severe plastic deformation methods. While early models have simplified the deformation during ECAP as simple shear, experimental observations and numerical simulations of fan-shaped deformation regions have motivated more elaborate analytical models that explicitly consider material flow through the region of most intense plastic straining. The two most prominent models (Beyerlein and Tomé, 2004), and (Tóth, 2003), allow to successfully predict texture evolution during ECAP, but their most basic versions have originally been limited to 90° ECAP tools. In this contribution, both models are extended to provide a detailed analysis of ECAP tools with arbitrary tool angles (in the practically relevant range from 90° up to 180°) that allows to fully describe novel developments in tool design. Most importantly, it is shown that a single free parameter is sufficient to modify the shape of the plastic deformation region, maintaining the simplicity of the corresponding original models. Explicit solutions are given in terms of strain rates and, by integration along a flow line, for strain tensor components, for equivalent strains per ECAP pass and for deformation gradients. The corresponding strain states predicted by both models are directly compared for arbitrary tool angles. It is further demonstrated that both models lead to similar strains in the two relevant limiting cases. Finally, exemplary fitting of experimental flow line data from Cu billets deformed in 90° and 120° tools allows for direct validation of the extended version of Tóth's model, demonstrating that it provides a sound basis for an in-depth experimental and theoretical analysis of plastic straining during ECAP in different tools and with varying processing parameters.},
  doi       = {10.1016/j.ijplas.2020.102755},
  publisher = {Elsevier {BV}},
}