Dissolvable metal supports for 3D direct metal printing

Additive manufacturing (AM) offers the ability to fabricate complex metallic structures and shapes in a layer-by-layer process. However, overhanging surfaces often require support structures to be fabricated and minimize thermally induced distortion. Unlike polymer AM processes, soluble sacrificial support materials have not been identified and characterized for metallic materials, and, as a result, support structures in 3D printed metals must be removed using additional machining operations. In this work, we demonstrate that sacrificial metal supports can be fabricated by taking advantage of differences in the chemical and electrochemical stability between different metals. As a demonstration, a stainless steel bridged structure with a 90° overhang was fabricated using a carbon steel sacrificial support that was later removed through electrochemical etching in 41 wt.% nitric acid with bubbling O₂. Open circuit potentials and potentiodynamic polarization curves were gathered to verify etch selectivity. No machining, grinding, or finishing operations were required to remove the metallic supports using this approach. This novel approach introduces new capabilities to AM that could drastically reduce the postprocessing needed for 3D printed metal components.