Fine Porous Stainless Steel TPMS Cellular Structures: Printability and Post-Processing Evaluation: Fid-Bau Portal

Fine Porous Stainless Steel TPMS Cellular Structures: Printability and Post-Processing Evaluation

Tyagi, Shivank A. / Manjaiah, M.

Triply periodic minimal surfaces (TPMS) are emerging as an excellent solution for manufacturing porous structures due to their smooth surface and mathematically controllable design features. The laser powder bed fusion (LPBF) additive manufacturing technique is the most preferable method for developing such complex lattice structures. However, this technology cannot be employed directly for applications demanding good surface finish. Post-processing methods, such as sandblasting, electro-discharge machining, laser polishing, chemical polishing, and traditional machining, are often used to overcome these limitations in the surface integrity of additively manufactured parts. However, these methods are not suitable for intricate complex structures or lattice structures. In contrast, methods like blasting and electrochemical polishing are most suitable for intricate geometries and lattice structures. Therefore, in the present study, blast finishing and electrochemical anodizing were employed to achieve the desired surface finish and integrity of very fine pore-sized (100 ~ 200 μm) SS 17–4 PH-based TPMS structures. Three different lattice structures, such as gyroid, diamond, and Schwarz, were considered for printing using the LPBF technique. A significant reduction in surface roughness was attained, with a maximum of 85% in electrochemical anodizing and 50% in blast finishing post-processing, even inside the intricate surfaces. In addition, the cell size and morphology were studied to correlate the designed and post-processed lattice structures. An increase in surface hardness properties was observed for blast finishing process. Based on the results, electrochemical polishing showed excellent capability in improving surface roughness properties.