Experimental setup to characterize flow-induced anisotropy of sheet metals

For many metals, a transient variation of the yield stress can be observed when changing the orientation of a load-path. Such behavior affects the manufacturing process itself, e.g. by increasing forming forces, altered material properties or springback of the manufactured components. Hence, the aim of this work is to develop a novel experimental setup to characterize hardening effects due to flow-induced anisotropy for sheet metals. The proposed experiment consists of two subsequent forming operations. Initially, a hydraulic bulge test is conducted, followed by torsion of the hemispherical preformed sheet. Such approach captures the effects of flow-induced anisotropy like cross hardening as could be proved for the example of the conventional deep-drawing steel DC04. The benefits of the presented setup are (i) high plastic strains in the pre-loading step and (ii) determination of several combinations of pre- and subsequent loading. (paper)