Abstract Scope |
Additive manufacturing (AM) has a great potential because it can produce a part by depositing metal layer by layer. Wire and arc additive manufacturing (WAAM) is one of popular AM technologies. It commonly applies wires as a feedstock which is melted by a focused heat source and solidify to a part following subsequent cooling. WAAM has higher productivity and lower production costs compared with the other AM technologies. Considering that WAAM has highly complex characteristics, there are still unclear phenomena of this technology need to be studied, such as process development, material performance and deposition part performance. Most of current researches focus on the microstructures, tensile performance and anisotropic mechanical properties, there are lack of a complete analysis of residual stress, which is one of the most important aspect of mechanical performance. The experiment measurement can present the distribution of residual stress, but the formation mechanism during the process could not be clearly explained. From the simulation perspective, the numerical simulation could reproduce the entire process and give an explanation but lack of validation. In this study, therefore, the basic material in WAAM stainless steel 308LSi and stainless steel 304 were applied as feedstock and substrate to build the wall and pipe WAAM parts. To meet the actual experimental conditions, an equivalent heat source was adopted to establish a thermal-mechanical model. The simulated residual stress distribution agrees well with that measured by contour method, proving the high accuracy of this model. The effect of layer number on the residual stress distribution was investigated to clarify the formation mechanism of residual stress and explore future accelerated calculation methods for WAAM. |