Parameter study of extrusion simulation and grain structure prediction for 6xxx alloys with varied Fe content

Increasing the recycled content is key to improve the sustainability of aluminum wrought alloys. However, Al scrap is often contaminated with Fe. Thus, coping with elevated Fe contents of wrought alloys is essential, but more Fe leads to more intermetallic phases, which impact extrudability and Peripheral Coarse Grain (PCG) formation. Coarse grains at the surfaces of aluminum extrudates can have a major detrimental influence on ductility, corrosion, and fatigue behavior. Therefore, it is desired to minimize the formation of PCG while keeping up the productivity of the process. PCG formation is dependent on local state variables such as temperature, strain, and strain rate, and second phase particles. In this work, we study extrusion of the aluminum alloys EN AW-6060, EN AW-6005A and EN AW-6082 with standard and increased Fe contents (0.2 and 0.7 wt. %). A parameter study of extrusion simulations was performed using the commercial extrusion software Altair (R) InspireTM Extrude Metal. Ram speed, billet temperature, and tooling temperature were varied, for a total of 245 simulations for each alloy. In order to tackle the large number of simulations and to increase computational efficiency, the evolution of microstructure was calculated after the extrusion simulation. For this purpose, the local state variables temperature, strain, and strain rate, were taken from a plane cut of the profile. These parameters along with experimentally determined initial microstructural properties (before extrusion) were used as input for a stand-alone microstructure simulation code. The final grain size distribution output of the microstructure simulations was compared to the microstructure obtained after extrusion experiments. In this way, our work furthers the understanding of the relationships between alloy composition, process parameters, and PCG formation.