Phenomenological modeling of anisotropy induced by evolution of the dislocation structure on the macroscopic and microscopic scale

Abstract

This work focuses on the modeling of the evolution of anisotropy induced by the development of the dislocation microstructure. A model formulated at the engineering scale in the context of classical metal plasticity and a model formulated in the context of crystal plasticity are presented. Images obtained by transmission-electron microscopy (TEM) show the influence of the strain path on the evolution of anisotropy for the case of two common materials used in sheet metal forming, DC06 and AA6016-T4. Both models are capable of accounting for the transient behavior observed after changes in loading path for fcc and bcc metals. The evolution of the internal variables of the models is correlated with the evolution of the dislocation structure observed by TEM investigations.

Voids and Microstructure Evolution in Aluminium Sheets during High Deformation

“…For high cold work a similar behaviour has been evidenced for DC04 steel sheets [14]. In aluminium the precipitates (usually known to exist for this alloy) retard the tendency to form dense dislocation walls [16], behaviour that can also lead to void reduction as the cold work value increases.…”

Comparison of two models for anisotropic hardening and yield surface evolution in bcc sheet steels

“…In this Levkovitch-Svendsen model (LSM), cross hardening is assumed to affect the flow anisotropy. As attested to by numerous applications of the THM (e.g., Boers et al, 2010;Bouvier et al, 2005Bouvier et al, , 2003Hiwatashi et al, 1997;Li et al, 2003;Thuillier et al, 2010;Wang et al, 2008) and the LSM (e.g., Barthel et al, 2013;Clausmeyer et al, 2014Clausmeyer et al, , 2011bNoman et al, 2010), both models are able to account for the observed effect of cross hardening on experimental stress-deformation data. As investigated and documented in the current work, there are otherwise a number of differences between the two.…”

“…Details of the mechanical testing procedure are given elsewhere (e.g., Clausmeyer et al, 2011b;Noman et al, 2010;van Riel and van den Boogaard, 2007). The region of the specimen subject to deformation is initially 45.0 mm wide and 3.0 mm high.…”

“…3 in the shear stage of discontinuous tension-shear loading. Indeed, Table 1 Material parameter values for DC06 determined for the THM (above) and the LSM (below) from room-temperature uniaxial tension, monotonic shear, cyclic shear, and orthogonal tension-shear, test data (Clausmeyer et al, 2011b) in the LSM (Fig. 3, right), s x is constant (e.g., 56 MPa for DC06 in Table 1).…”

Properties of FA-CVD silica coated steel sheet after deformation: coating integrity and corrosion related forming limit curve

“…18 Plastic deformation of DC06 steel sheet leads to fragmentation and evolution of slip systems already at low strains (5%) 19,20 and may induce cracking of the coating. 11 However, the strain may be inhomogeneously distributed within the steel sheet, resulting in the presence of grains with comparably low deformation, or it may be dispersed in a surface layer.…”