Investigating Rust with SEM

[metalman8357]

Hi all,

I have a part that was shortly in service and shows red rusting on the surface. The material is 316, and my suspicion tells me that the red rust is just run-off from some other component in the system but I can't be certain just from looking. If I send these parts out for SEM, can I determine if the base material is still non-corroded, and the red rust is from some other source? Would this be difficult to do?

 

[EdStainless]

Yes, it is delicate.
You need to carefully clean a portion of the surface and check for underlying damage.
And look at the surface for signs of oxidation or surface Cr depletion.

Do you have multiple pieces of hardware?
I would try cleaning one in mild phosphoric acid.
If it cleans right up and there is no pitting visible then it is just staining from something else.
If it won't clean and/or there are significant pits then the piece is corroding itself.

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