Electrochemical polishing process of additively manufactured IN738LC fine channels

The surface of the flow channel produced by laser powder bed melting has defects such as protrusions, sticky powder, and semi melted powder. Due to poor accessibility and fluidity inside the small channel, polishing becomes more difficult. This work solves the accessibility problem by promoting electrolyte circulation through peristaltic pumps. In response to the uneven size of defects on the inner surface made by LPBF, we have developed and optimized overpotential polishing process. After polishing for 30min, the surface roughness (Sa) of the inner surface decreased from 10 μm to 2.5 μm–3.5 μm, achieving high selective polishing of the inner surface of IN738LC fine channels.