From Wire to Seamless Flow-Formed Tube: Leveraging the Combination of Wire Arc Additive Manufacturing and Metal Forming

Flow forming is a metal-forming process for producing axisymmetric hollowed tubes starting from cylindrical workpieces. In cases where the preformed tube includes defects, impurities or inconsistencies, the final product may not withstand the required standard. In this work, the preformed tubes were produced by metal wires melted into the desired geometry using a gas-metal arc-welding robot. Two geometries were built to allow either forward or backward tube spinning of parts from ER-70S-6 and AWS ER316L welding wires. Following the building process, the parts were machined to fit a flow-forming operation. The mechanical and metallurgical properties of the wires, preformed cylinders and final tubes were compared with conventionally manufactured material. Results indicate that the mechanical properties of the products of the proposed process were superior to those of conventional processing. Applying flow forming to wire-arc additive manufacturing yields a deeper understanding of the material qualities over a large building envelope and can be used as valid quality criteria for the additive manufacturing process qualification.