Additive Manufacturing of 17-4PH Stainless Steel Based Complex Angles Tool and Workpiece for Electrochemical Machining

Additive Manufacturing (AM) facilitates the creation of complex geometries that are often impossible to achieve using traditional manufacturing methods. A key area of current research in AM is the design of extreme angles without requiring external support structures. Electrochemical machining (ECM), a non-traditional subtractive process, removes material atom by atom through anodic dissolution, making it particularly effective for difficult-to-machine materials such as 17-4 PH stainless steel (SS), a high-strength alloy commonly used in aerospace and biomedical applications. The integration of AM with ECM holds significant promise to produce high-performance, functionally graded components with tailored properties for critical applications.

In this study, 17-4 PH SS components with complex geometries and extreme angles geometries of 70°, 50°, and 30° were fabricated using Laser Powder Bed Fusion (L-PBF)-based AM. Mass loss rates with respect to the relative densities are considered for complex geometries to understand material dissolution patterns. The study continues by simultaneously printing the inner anode and outer cathode with a minimal inter-electrode gap (IEG) of 500 microns to facilitate precise ECM. The inner anode was printed with variable density to ensure easy tool removal after ECM. However, the heterogeneous microstructures inherent in AM introduce challenges during ECM due to variations in electrochemical behavior across material interfaces, resulting in differential dissolution rates, galvanic effects, and localized over-machining.

To evaluate the extent of these heterogeneities, electron microscopy combined with X-ray computed tomography (CT) was conducted on the 3D-printed designs before and after ECM. This investigation provides insights into the impact of microstructural variability on ECM performance and highlights strategies to mitigate machining inconsistencies. The successful integration of ECM and AM demonstrated in this research paves the way for enhanced post-processing of multi-metal AM components, offering greater precision and efficiency in the fabrication of advanced components for aerospace, biomedical, and precision engineering applications.