Laser powder-bed fusion printability of micro-holes in SS316L(B) and post-processing through electrochemical micro-machining

Laser-based powder-bed fusion (LPBF) has become befit choice for fabricating intricate and precise metal parts using the additive manufacturing (AM) process. The micro-scale manufacturing industry continuously evolved and captured a huge market in various engineering applications for demand in miniaturized high-performance products. However, achieving precision and tolerance with a better surface finish has been challenging. In this article, the micro-scaled features (micro-holes) fabricated via LPBF process with SS316L material have been investigated for geometrical accuracy, followed by electrochemical micro-machining (ECMM) as post-processing for micro-hole finishing. The fabricated micro-holes with less than 100 µm diameter were found to be blind holes rather than complete through holes. The results show that the dimensional inaccuracy of micro-holes is in the range of 17–36%. However, the ECMM post-processing ensured the through-holes even for a hole diameter of 50 µm. Further, the post-processing operation improves dimensional accuracy and roundness by 31–79%, and 21–130%, respectively. In addition, the mechanical properties of the SS316L part printed with a hexagonal scanning strategy have been evaluated. The printed samples experienced residual stress from –91 MPa to 73 MPa, while a heat-treatment cycle relieved the induced residual stress without altering the microstructure significantly. The heat-treated samples exhibit noticeable improvement in yield and ultimate strengths. However, the elongation percentage of the heat-treated part is reduced by 2–10% at various strain rates. The heat-treatment cycle caused improvement in the specific wear rate.