A process that normally lowers the corrosion resistance had the opposite effect when applied over an alternate known-good option. Chromium passivation is the known-good, manganese passivation is known to make it worse. Manganese-passivating chromium-passivated stainless looks like it’s way more corrosion resistant than either passivation on its own and non-passivated stainless
Also, daily reminder, stainless steel corrodes. It forms a corrosion layer that is hard and doesn’t change size compared to the base metal (unlike rust on normal steel, which expands), but it can still be prone to erosion particularly in oxygen-depleted water. Even 316.
I’m kinda glad stainless steel corrodes in the end. Else it would become a micro-fragment polluter like plastic.
I’d say a major difference is that steel is an alloy of natural inorganic elements. The components aren’t especially toxic, at least not any more than how they already exist in the environment. Microplastics are entirely man made and don’t have any natural, decent way to be broken down organically. Would you count sand as a pollutant? It’ll last way longer than plastic and we certainly ship it around everywhere. Eating sand is just part of marine life
