Can steam exhaust channels be mild steel?

[ron61630]

The B17 has a steam channel that connects the exhaust  from all three cylinders
You can get eith a CI or gunmetal casting, but i was wondering what drawbacks ( rusting?)  there would be if i fabricated it from mild steel , apert rom a cost saving  ( plus i am enjoying drawing out all the bits...lol 

[millman]

How about fabricating it in brass, no rusting problems, silver solders beautifully.

[tenor]

If it is for exhaust, the cylinder oil will prevent rust well enough. Another way to look at it - which will last longer, you or the manifold?
Martin