Experimental and analytical investigations of extrusion seams in magnesium hollow profiles

中空型材的挤出主要用分流模进行。在模具的预燃室中的桥处，坯料材料被分成两个或更多个单独的材料流。在材料通过模具凹口离开模具之前，材料在焊接室中结合在一起。材料分离和随后的焊接在型材中的挤压方向上产生挤压缝。如果挤压是坯料对坯料进行的，则会出现额外的交叉接缝。挤压缝的形成对挤压制品的质量至关重要，而铝合金空心型材的分流模挤压成形是一种常见的挤压成形方法，而镁合金空心型材的分流模挤压成形则几乎没有研究。由于对镁合金空心型材挤压缝的形成、挤压缝的微观组织特征及其对力学性能的影响缺乏必要的科学研究，因此有必要开展基础性研究。因此，该项目包括微观结构的广泛表征和挤压参数的挤压缝的机械性能。此外，为了优化镁空心型材的挤压，将进行有限元模拟。

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.