I bought a cheap, old, pawnshop special for just this purpose--an old
10" B&D (IIRC) mitre saw with a steel table and fence. I think I paid
less than $40 for it. Use it exclusively for cutting mild steel and
other such metal, an infrequent operation. I scrounged a thrown-away
stainless steel cabinet on which the saw sits--it even has a ss
backstop/splash guard to keep some of the spray in check.

I wouldn't think of cutting steel with the 12" Delta I use when running
trim, though I have cut aluminum sheet (siding, soffit, etc.) on it. I
figure the cast aluminum on the saw won't be damaged by the aluminum
"sawdust" (but the bearings could be an issue--have to think about that
one).

Don't forget a face shield, gloves and ear protection--cutting steel
with abrasive blades is a loud and dirty proposition.

Dan