Characterization of metal-forming processes with respect to non-monotonity

The method of severe plastic deformation (SPD) is often used to produce bulk ultra-fine grained materials. SPD is a procedure, whereby the structure of the material changes from the initial coarse grained state to ultra-fine grained structure. For these techniques shear deformation as well as the so-called non-monotonic deformation are characteristic. The aim of this paper is to compare different metal-forming techniques with respect to non-montonity of deformation. A quantity and its calculation for the characterization of non-monotonity are introduced. Study of different metal-forming processes (simple shear, ECAP, upsetting) concerning non-monotonity and the comparison of these results are presented.