steel pipe for porch column
 

I need to replace my porch columns and was thinking about using steel pipe. I was thinking of using something up to 4" OD. It's a small porch with a small gabled overhang, so I only have 2 posts to replace. It's a wooden overhang and a concrete porch. Any thoughts as to the pipe's wall thickness or how to attach it to them to the porch? Pros and cons? Thanks for the help.

Lowes and Home Depot carry Vinyl with aluminum tubing cored coloums.
Steel is just going to rust out.
If you Googel Porch Coloums hundreds of sites come up.