Study on Forming Characteristics and Process Stability in Wire Arc Additive Manufacturing of 5356 Aluminum Alloy

To solve the problems of unstable deposition and poor accuracy in wire arc additive manufacturing (WAAM) of 5356 aluminum alloy, the arc current of MIG heat source was optimized by changing the corresponding wire filling rate (V_f) from 4 to 10 m/min. The results showed the optimal V_f at 8 m/min decreased the combustion stiffness angle of the arc from 62.9° to 53.3° and reduced the fluctuation area of arc plasma by 15.9%. The combined effects benefited to optimize the droplet transfer from short-circuit to fine spray mode. The strengthened deposition stability decreased the porosity of the WAAM deposited thin-walls from 0.18 to 0.048% and improved the forming accuracy by 39%. The microhardness distribution uniformity was increased with the increasing V_f to 8 m/min, and the ultimate tensile strength and elongation reached the maximum of 297.01 MPa and 27.03%, respectively. The optimized arc current not only improved the combustion characteristics of MIG arc, but also promoted the melt flow to enhance metallurgical reaction, thereby increasing the deposition stability and quality.