Analysis of roping in an AA6111 T4P automotive sheet in 3D deformation states

Abstract

A three-dimensional (3D) crystal plasticity based finite element model has been developed to simulate the development of a rope-like surface roughness profile, i.e., roping, in a commercial AA6111 T4P sheet upon stretching. The electron backscatter diffraction (EBSD) mapping was done in a selected volume from the sheet surface down to about 1/3 thickness. The resultant 3D texture data was directly incorporated into the finite element model, and the constitutive response at an integration point was described by the single crystal plasticity theory. It has been demonstrated that (i) the 3D spatial distribution of specific grain orientations, i.e., the {001}〈100〉 (Cube) and {011}〈100〉 (Goss), is the determinant factor for roping, (ii) the roping is initiated at very low strains and it intensifies with increasing strain without significant change in spatial distribution, and (iii) a surface cladding layer free of textural alignment may reduce the roping but only if the cladding is very thick.