Experimental analyses and numerical modeling of texture evolution and the development of surface roughness during bending of an extruded aluminum alloy using a multiscale modeling framework

Abstract

Bending is an important strain path in various metal forming operations as well as vehicle crashworthiness. In the present study, the bending behavior of an extruded aluminum alloy AA6063-T6 is investigated using wrap bending tests. The focus of the work is on understanding the relationship between heterogeneous plastic deformation, strain localization, the accompanying texture evolution and the development of surface topography effects during wrap bending. In these regards, wrap bending experiments are conducted and the bendability of the as-received material is assessed. The development of micro-slip bands, shear localization and the formation of surface undulations through-thickness of the bend are analyzed using conventional metallography and scanning electron microscopy (SEM). The initial microstructure, grain size distribution and texture evolution during bending are analyzed using electron backscatter diffraction (EBSD) measurements. The surface topography of the bent specimen is analyzed using 3D laser scanning profilometry. Next, a 3D multi-scale modeling framework is used to simulate wrap bending using crystal plasticity based finite element methods (CPFEM). The simulated results for strain localization, texture evolution and surface topography development show good agreement to the corresponding experimental findings. The modeling results are further analyzed to understand the relationships between initial microstructure, strain localization and surface topography development. A set of bending simulations is also conducted using 3D synthetic microstructures to further investigate the relationship between through thickness clustering of similarly oriented grains, initial microstructure and the developed surface topography after bending. A possibility to achieve a lower surface roughness by altering the through thickness locations of similarly oriented grain clusters has been demonstrated. Lastly, it has been numerically verified that by eliminating or by reducing the tendency towards clustering of similarly oriented grains within the microstructure, a transition from a ridging to an orange peel type surface topographic behavior can be achieved.