Active vs. Passive Stainless

[jtowne]

I'm looking at the MIL-STD-889 galvanic table and there are passive and active stainless steels. What is the difference? Since I have an application involving stainless screws in an aluminum body I would prefer to use the active stainless as it is closer to the aluminum on the table.

Are stainless hardware suppliers going to know what I'm asking for when I request an active 430 alloy screw?

Thank you.

 

[EdStainless]

You don't get to choose, the environment does. If SS is active, it means that it is corroding.
It is good that you are looking at the table. It gives you an idea of what can happen.
If a system is dry there will be no corrosion. If it is wet, and conditions favor corrosion of one of the metals then you Al will be in trouble.
You will either need to go to a less corrosion resistant fastener alloy, or live with some local galvanic attack of your Al. For years various bronzes and brasses have used with Al, there is rarely enough galvanic difference to drive much serious corrosion. On the other hand sometimes you get corrosion of the fasteners.

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