Experimental and analytical investigations of extrusion seams in magnesium hollow profiles

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The extrusion of hollow profiles is predominantly done with porthole dies. At the bridges in the prechambers of the die the billet material is divided into two or more separate material flows. Before the material leaves the die through the die recess the material is joined together in the welding chamber. The material separation and later on the welding cause extrusion seams in the extrusion direction in the profiles. If the extrusion is done billet-on-billet additional cross-seams occur. The formation of the extrusion seams is very important for the quality of the extruded products.Whereas the extrusion of hollow profiles with porthole dies is well known for aluminum alloys, there are almost no research regarding the extrusion of magnesium hollow profiles. Due to the lack of essential scientific findings about the formation of extrusion seams in magnesium hollow profiles, about the microstructural characteristics of the extrusion seam and the effect on the mechanical properties a fundamental research is necessary. Therefore the project includes a broad characterization of the microstructure and the mechanical properties oh the extrusion seams in dependence of the extrusion parameters. Furthermore, in order to optimize the extrusion of magnesium hollow profiles accompanying FE-simulations will be carried out.