Comparative Corrosion Performance of additively and conventionally manufactured AISI 316L Stainless Steel in Molten FLiNaK Salt at 700°C

As molten salt reactors gain traction, the demand for structural materials that combine good corrosion resistance with cost-effective manufacturability grows. This study investigates the corrosion behaviour of Laser Powder Bed Fusion processed AISI 316L stainless steel in molten FLiNaK salt at 700°C and compares it with that of wrought counterparts. Samples were exposed to the salt for up to 500 hours in a nitrogen environment and were characterized with light optical microscopy post exposure. The wrought samples exhibited intergranular corrosion and progressive grain detachment with increasing exposure time. In contrast, Laser Powder Bed Fusion samples experienced more localized surface degradation, potentially linked to their more complex microstructure. These findings suggest that additive manufacturing introduces corrosion mechanisms different from those in wrought steel when exposed to molten fluoride salts.