Increasing the manufacturing efficiency of WAAM by advanced cooling strategies

Abstract

Wire- and arc-based additive manufacturing (WAAM) is a promising technology for large-scale additive manufacturing of metallic components. However, due to the high heat input by the electric arc, interpass cooling time decelerates the average manufacturing speed. Since future applications aim to the production of large structural steel components, the manufacturing speed is a key parameter to make WAAM usable for civil engineering. Within the scope of this paper, different process cooling strategies are weighed up against one another with regard to efficiency, impact on the process, as well as to the influence on the microstructure of the processed steel. For the thermal evaluation, welds on vertically placed plates were performed using the gas metal arc (GMA) process. As far as different cooling methods are concerned, the standard GMA process is carried out with water bath cooling, high-pressure air cooling and also with aerosol cooling. Temperature curves were determined using thermocouples which are dipped into the molten pool. The evaluation of the microstructure and the hardness is carried out by means of cross sections and Vickers hardness tests. The results show that aerosol cooling can be a promising addition to WAAM as it can be applied during welding and is capable to modify the t8/5 time and, therefore, the mechanical properties of the steel.