Black Oxide 18/8 Vs. 316 Stainless

[13]

Can anyone comment on the effectiveness of a black oxide coating on 18/8 stainless steel screw?
The application environment would be marine, on a ship/boat, prob. getting splashed with saltwater every now and then, but not being submerged..

Also can you comment on 18/8 Vs 316? In this environment.

I would appreciate any feedback.

Thanks!

 

[unclesyd]

Given my many trials and tribulations in and around and under salt water forget about 18/8 SS and stick with 316 SS.

An 18/8 fastener is essentially a nondescript item in my book.

 

[kenvlach]

The black oxide may help if kept waxed.

18-8 is 304ish without a pedigree.
ASTM F593 has 18-8 compositions lumped into an Alloy Group 1 (304, 304L, 305, 384, 18-9LW, 302HQ, plus some crappy free-machining versions supposedly only allowed w/o buyer approval). All are inferior in seawater resistance to 316 (which has an added 2% Mo):

Spray concentrates via evaporation in many above surface locations, often warmer, so 304-group alloys perform even worse than submerged unless frequently washed with freshwater.

 

[EdStainless]

You will still need wax or some kind of protection on the 316, especially to keep the threads from galling.
At least with 316 you stand a chance.

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