Computational welding simulation of a plasma wire arc additive manufacturing process for high-strength steel

Wire arc additive manufacturing (WAAM) processes have many advantages including the ability to repair worn or damaged components. Compared to other arc processes, plasma welding constricts the arc, which leads to a highly concentrated energy input. Thus, an understanding of the heat input distribution and its consequences such as transient temperature field, transformation, build up of stresses and distortion is of great importance for applications with high-strength steels. Numerical simulation can provide an important input for this evaluation.

However, the plasma arc is challenging to simulate due to its high energy density and thus steep gradients, as standardly used heat sources in commercial software often only represent classical arc or beam processes. Therefore, this study deals with the development of an accurate heat source model based on standard implemented heat sources in Simufact Welding. Therefore, welding experiments were performed on steel and thermal cycles representing the quasi-stationary temperature field were recorded. Subsequently, metallographic examinations were performed describing the fusion and heat affected zone. On this basis, distortion simulations were carried out and validated using further welding experiments. Using the obtained results, path planning, idle time and consequently interpass temperatures and the resulting heat flow can be analysed.