P 1537 - Wood-steel hybrid construction methods using the example of bending-stressed load-bearing elements

P 1530 - Extension of the process limits in GMAW hot-wire welding by adapting the material and energy input by means of upstream hot-wire preheating Despite the widespread use of GMAW (gas metal arc) welding processes, these processes have the inherent disadvantage of coupling material and energy input. In mechanised applications, an arc filler wire (hot wire) can be used to compensate for this disadvantage. However, the hot wire current causes the magnetic blowing effect, which in turn limits the process window and variability of the process. The aim of this research project is therefore to develop a MSG hot wire process with upstream ohmic filler wire preheating (between two current nozzles) for joint welding, build-up welding and additive manufacturing. In addition to increasing the deposition rate, the aim is to achieve decoupling and targeted control of the material and energy input depending on the application. As part of the research project, the MSG hot wire process with preheated hot wire was analysed in detail both in terms of its process characteristics and its potential for various welding tasks. It was shown that the hot wire feed has a significant influence on the process, with an approach angle of 50° leading to a more stable and homogeneous seam formation. The MSG process itself is primarily determined by the electrical heating and is not influenced by the preheated hot wire, whereby optimisation of the wire feed and gas purging can further increase the process stability. The process shows excellent suitability for single-layer welding of 8 mm thick mild steel sheets and also has great potential for welding thicker sheets (up to 20 mm). In terms of additive manufacturing and build-up welding, the process enables high productivity and good mixing, although the path planning must be adapted accordingly. A steep wire feed angle (65°) leads to a strong interaction between the filler material and MSG wire, which requires short arcs. In addition, the preheating length should not exceed 30 mm to ensure a stable process. Overall, the GMAW hot wire process shows great potential for various welding tasks and application scenarios, especially in the field of joint welding and additive manufacturing, whereby the adjustment of the process parameters makes a decisive contribution to optimisation. The objective of the research project was achieved. Publication: March 2025 Authors: T. Ungethüm, T. Dilger, P. Schilling, E. Spaniol, M. Schäfer, U. Füssel, H. Schmale