Solid-state bonding of oxide-covered aluminium surfaces in metal forming

固态键合是一种物理过程，通过对两个表面施加压力可以生产材料复合材料。根据定义，固态键合发生在低于复合材料的熔化温度且不添加填充材料的温度下。实现固态粘合所需的压力和表面膨胀的成形工艺包括辊包覆、累积辊粘合和热挤压，以及直接回收铝废料的回收工艺。到目前为止，这些工艺只研究了它们的工艺特定参数及其对所得键的影响。到目前为止，物理关系还没有足够的可转移性。这种可转移性有时在个别工艺类别中也缺乏，因为焊接区域的成形条件通常不完全清楚。目前还没有普遍适用的焊接强度预测的物理模型，能够在整个相关温度和应变速率范围内产生精确的结果。此外，没有实验方法来确定局部焊接强度。研究项目的目标是定量确定物理因素对氧化表面局部焊接的影响。为此，导出了确定局部焊接强度的实验方法，并开发了根据焊接区成形条件预测焊接强度的计算方法。为了产生焊缝，采用基于热挤压的实验方法，可以在已知成形条件下对两个氧化表面进行定向焊接，并在已知焊缝位置下进行样品提取。所获得的知识用于推广和验证现有的焊接模型。最后，提出了促进氧化表面焊接的方法。

Solid-state bonding is a physical process by means of which material composites can be produced by applying pressure to two surfaces. By definition solid-state bonding takes place at a temperature below the melting temperature of the composite partners and without the addition of a filler material.Forming processes in which the pressures and surface expansions required for solid-state bonding are achieved include roll cladding, accumulative roll bonding and hot extrusion, as well as recycling processes for the direct recycling of aluminium scrap. So far, the processes have only been researched with regard to their process-specific parameters and their influence on the resulting bond. Up to now, there is no sufficient transferability of the physical relationships. This transferability is sometimes also lacking within individual process classes, since the forming conditions in the welding zone are often not exactly known. Currently no generally applicable physical models for weld strength prediction exist, which are capable of producing precise results over the entire relevant range of temperatures and strain rates. Furthermore, there are no experimental methods for determining local welding strengths.The goal of the research project is the quantitative determination of the influence of physical factors on the local welding of oxide-covered surfaces. For this purpose, experimental methods for determining a local weld strength are derived and calculation methods for predicting the weld strength depending on the forming conditions in the weld zone are developed. To produce weld seams, an experimental method based on hot extrusion is to be used, which allows the targeted welding of two oxide-covered surfaces under known forming conditions as well as sample extraction with a known weld seam position. The knowledge gained is used to generalize and validate existing welding models. Finally, methods are derived to promote welding of oxide-covered surfaces.