Studies on the reproducibility of the magnetic pulse welding in the case of an asymmetric impact

本课题的研究目的是保证磁脉冲焊接接头的坚固性和设计性能。在这里，研究部分是基于已经确定的冲击焊接物理过程变量（例如碰撞角和碰撞点速度）和焊缝下边界的描述。根据最新的技术和自己的研究，表面形貌的具体变化可以扩大焊接窗口，并允许设置接头的性能。此外，研究表明，结合某些工艺参数（如加速度距离对碰撞角的影响以及电流的调节），可以影响射流的形成，进而影响焊接接头的形貌（波状或扁平界面、相形成）。该研究项目还旨在确定和确保磁脉冲焊缝（周期性和动态载荷）在焊缝形貌方面的力学性能，并希望检查高工艺速度对塑性变形后焊接区域硬化的影响。为了评价焊缝质量，将焊缝表面建立为磁脉冲焊缝的质量特征，然后将其与物理过程变量相关联。另一个重要的焦点是确定能量平衡，以便将结果转移到其他材料组合中。根据主题，将与项目A5 （PTU，碰撞焊接）和项目A8 （IWW，微观结构机制）合作进行测试。此外，还将与A3项目（MPIE，表面化学）合作，最后将检查氧化层的影响。所获得的结果将使产品设计适合焊接，具有灵活的焊接接头特性布局，以适应特定的应用。此外，通过与A5项目的合作，这些结果将支持通过数值模拟对接头性能的预测。

The aim of this research subject is to ensure the robustness and design of the properties of the welded joint for magnetic pulse welding. Here, research is based partly on physical process variables which had already been determined for impact welding (e.g. collision angle and collision point velocity) and the description of the lower weld seam boundary. According to the latest state of the art and own research, specific changes in the surface topography enable an enlargement of the welding window and allow to set the properties of the joint. Furthermore, the research has shown that, in conjunction with certain process parameters (e.g. influence of the acceleration distance on the collision angle as well as the regulation of the current), the jet formation can be influenced, which, in turn, effects the morphology of the welded joint (wavy or flat interface, phase formation). This research project also aims to determine and secure the mechanical properties of magnetic pulse welds (cyclical and dynamic load) with regard to the morphology of the weld and wants to examine the influence of high process velocities on hardening in the welding zone after plastic deformation. In order to evaluate the quality of the weld seam, the surface of the weld seam will be established as a quality feature for magnetic pulse welds and will then be correlated to the physical process variables. Another important focus will be the determination of the energy balance so that the results can be transferred to other material combinations. Depending on the topic, tests will be performed in cooperation with the project A5 (PTU, collision welding) as well as A8 (IWW, microstructural mechanisms). In addition, there will also be a cooperation with the project A3 (MPIE, surface chemistry) and, finally, the influence of the oxide layer will be examined.The acquired results will enable a product design suitable for welding with a layout of the properties of the welded joint which is flexible, in order to suit specific applications. Additionally, in cooperation with the project A5, these results shall support the prediction of the properties of the joint via numeric simulations.