Dissolvable metal supports for printed metal parts

Temporary support structures are an inconvenient necessity in Direct Energy Deposition (DED) and Powder Bed Fusion (PBF) printed metal parts. Used to reduce thermal distortion and brace large overhands, support structures often require post-print machining operations to remove, adding costs and processing delays. This preliminary work demonstrates that soluble, sacrificial metal supports can be fabricated in DED and PBF printers by taking advantage of small differences in the chemical and electrochemical stability between different metallic alloys. For DED printing, we demonstrate this process by printing stainless steel bridge structure with 90 overhang and printed carbon steel acting as a sacrificial support. For PBF printing, a PBF printed stainless steel part was first printed and then carburized to reduce the free chromium at the surface. Since the support/component interface is only ~100 μm in size, this interface becomes highly susceptible to chemical and electrochemical dissolution. In both cases, the component was separated from the supports in a solution of nitric acid and KCl under mild electrochemical bias. No machining, grinding, or finishing operations were required to remove the metallic supports. These novel approaches introduce new capabilities to additive manufacturing that will drastically reduce the post-processing needed for 3D printed metal components.