Rust between two metal parts

[rmastro]

I have two rotating parts, one is 440 stainless the other is 1117 steel with oxide coat. Rust is forming between the two parts, but only where they come in contact. This happens in a normal 40-50% humidity environment.

The sst part does not rust on its own. The steel part has an oxide coat, but doesn't show brown rust, until it comes in contact with the stainless.

help would be much appreciated.

Option, coat steel part, coat sst part, other???

 

[mcguire]

Yeah, you have a tough combination there. The rust will form continuously on the 1117 and then be abraded off so more can form. The 440's passivity will be ruined by the iron oxide, so it corrodes.
You need to protect the 1117 from the fretting type oxide. Is this an application for a self-lubricated bushing?

 

[rmastro]

Thanks for the help. Do you have a source you can recommend for this bushing, or a treatment to the steel part that could help.