Effect of temperature and substrate geometry on single aluminium weld bead geometry deposited by Wire Arc Additive Manufacturing: Proposition of an experimental procedure

The study of the Wire Arc Additive Manufacturing (WAAM) technology is in expansion mainly thanks to its high deposition rate, its large range of available materials and its inexpensive and wide distribution of its equipment. Being able to control and predict the deposition geometry is a first step toward the technology mastering. To achieve this, numerous studies have focused on the investigation of welding parameters (such as current, tension and energy modulation) and deposition strategies (such as wire feed speed, travel speed, trajectory and dwell time) for a given material. This work proposes to consider two additional parameters, not yet studied, which are the temperature, at which the deposition is made, and the geometry of the substrate receiving the deposition. These two new parameters allow to consider experimental conditions closer to a real fabrication. This study investigates thus their effects on aluminium deposition thanks to an experimental procedure using a heating device and cylindrical substrates of different diameters. Simple simulations are performed to evaluate the thermal conditions of the experiment. From these simulations, a unique indicator is used to represent the whole process conditions. Welded beads are scanned and a circular model is used to model their cross-sections. The implemented experiment shows that the evolution of the dimension of this circle is linked to the evolution of the process conditions. Indeed, hotter conditions, induced either by a higher initial temperature or by different substrate geometries, generate a more spread weld bead. Knowing this trend allows to extract a model and opens the possibility to predict the weld bead dimensions.