Fabricating 316 L stainless steel unsupported rods by controlling the flow of molten pool via wire arc additive manufacturing

Fabricating unsupported inclined rods using additive manufacturing poses significant challenges, limiting the design and manufacturing of lattice structures. This study introduces a method for controlling molten pool flow to successfully fabricate unsupported rods with varying diameters (4.6-9.3 mm) and inclination angles (-30 degrees to 90 degrees) using wire arc additive manufacturing. The key contributions of this research lie in enabling the fabrication of negatively inclined unsupported rods and investigating the influence of arc heat input on the deposition process, molten pool behavior, microstructure, and mechanical properties. By effectively controlling the molten pool flow, this method significantly reduces constraints on structural design, facilitating the fabrication of multi-angle lattice structures. It is observed that rod diameter negatively correlates with arc heat input per volume. Tensile strength initially increases and then decreases with diameter increment. Additionally, fabricating negatively inclined rods requires additional heat input, resulting in slightly inferior mechanical properties compared to positively inclined rods. The demonstrated applicability of the proposed method through the stable fabrication of screw rods and arc-curved rods showcases its potential for various lattice structure designs. Furthermore, the limitations of minimum rod diameter and inclination angle are discussed, determined by arc energy equipment, machine tool accuracy, and torch interference. This study advances additive manufacturing techniques by enabling the fabrication of unsupported inclined rods and expanding the design space for lattice structures.