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

固态结合是一种物理过程，通过该过程，可以通过向两个表面施加压力来生产材料复合材料。根据定义，固态结合是在低于复合材料熔化温度的温度下进行的，并且不添加填充材料。实现固态结合所需压力和表面膨胀的成型工艺包括辊压包覆、累积辊压结合和热挤压，以及直接回收铝废料的回收工艺。到目前为止，仅研究了这些工艺的特定工艺参数及其对所得粘合的影响。到目前为止，还没有足够的物理关系的可转移性。由于焊接区的成形条件通常不确切，因此在个别工艺类别中有时也缺乏这种可转移性。目前，不存在用于焊接强度预测的普遍适用的物理模型，其能够在整个相关的温度和应变率范围内产生精确的结果。此外，还没有确定局部焊接强度的实验方法。本研究项目的目标是定量确定物理因素对氧化物覆盖表面局部焊接的影响。为此，导出了用于确定局部焊接强度的实验方法，并开发了用于根据焊接区中的成形条件来预测焊接强度的计算方法。为了产生焊缝，将使用基于热挤压的实验方法，该方法允许在已知的成形条件下对两个氧化物覆盖的表面进行有针对性的焊接，以及在已知的焊缝位置处进行样品提取。所获得的知识用于推广和验证现有的焊接模型。最后，方法得到促进焊接的氧化物覆盖的表面。

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.