What type of corroding material is this?

[uzman1243]

Hi,

So I was thinking about corrosion and I came across this structure:

Do you think the inner metal/alloy that is corroding is steel?

Also, what do you think the outer layer (in white) is? perhaps the metal is just coated with paint to avoid corrosion?

Finally, what type of corrosion do you think its undergoing? General Corrosion, Galvanic corrosion, uniform corrosion and so on.

 

[Astronuc]

The mesh seems to be expanded metal, possibly made of a steel, e.g., 1008. The white covering seems to be paint. It's possible that the post is steel. The dark corrosion product could be magnetite, perhaps with a spinel component.

Is the post galvanized?

It is possibly uniform, galvanic corrosion with some pitting and some crevice corrosion at the edge of the paint. If there is aluminum in contact with the post, then that would drive galvanic corrosion.