Corrosion resistance behavior of additively manufactured 316L stainless steel in nuclear environments

Additive manufacturing (AM) offers several unique advantages, including greater efficiency, design flexibility, and microstructural refinement. However, the corrosion resistance of AM-produced alloys remains a field of debate owing to the effects of printing parameters on porosity, microstructural properties, and passive film stability. The present study reports the printing of 316 L stainless steel (SS316L) specimens using the laser powder bed fusion (LPBF) technique and the subsequent testing of their corrosion resistance in 0.6 M NaCl, H2O2 (0.01 M and 0.5 M), and Na2SO4 (25 mM) solutions. The specimens were produced under a wide range of printing parameters, including scanning speed (500–1100 mm/s), laser power (150–330 W), and hatch distance (0.09–0.125 mm), with varying hardness, electrochemical behavior, porosity, and grain morphology and size. The results showed that an appropriate combination of scanning speed and laser power is crucial for achieving a refined microstructure and reduced porosity. The outcomes of electrochemical (EIS and PDP) studies suggest that AM-printed alloys exhibit better corrosion resistance than wrought 316 L, with specimen #19 demonstrating the best polarization resistance (Rp) and the lowest current density (Icorr). The specimen was fabricated at a laser power of 230 W, a scan speed of 1100 mm/s, and a hatch distance of 0.09 mm, respectively. The results further show that, in NaCl solution, porosity is a crucial factor in pitting initiation. On the other hand, in H2O2 solution, an increase in peroxide concentration stabilizes the passive films.