Effect of deposition speed on twin tungsten electrode-wire electrode indirect arc additive manufacturing for 316L stainless steel

To achieve decoupling control of heat input and deposition efficiency, a twin tungsten electrode - wire electrode indirect arc additive manufacturing (TTWIA-AM) was proposed. Two tungsten electrodes and one wire electrode were connected to the negative and positive terminals of the power supply respectively. A single-way multi-layer stainless steel thin-walled wall was fabricated using 316L austenitic stainless steel wire. The influence of deposition speed on the forming, microstructure and mechanical properties of the thin-walled wall was studied. The results indicated that a deposition speed ranging from 5 mm/s to 8 mm/s could ensure that the additive process did not collapse, and the deposition efficiency can reach 3.73 kg/h. When the deposition speed increased from 5 mm/s to 8 mm/s, the flow phenomenon gradually disappeared, and the forming quality was significantly improved. Due to the increase in deposition speed, the heat input decreased, and the grain size gradually became smaller. The transverse tensile strength increased from 522.17 MPa to 560.68 MPa, but the longitudinal tensile strength showed a trend of increasing first and then decreasing. Analyzing the tensile fracture surface, it was found that the fracture mode was ductile fracture. Due to its high efficiency and low heat input characteristics, the TTWIA-AM shows great application potential.