Usual rule of thumb for cutting steel is at least 3 teeth per metal
thickness and speed of 150 to 300 SFPM -- but I've discovered a
notable exception with very thin steel. .

Had some .020" steel siding to cut. Usual practice is to use snips
for the fitted parts like angles that meet roof gables. Neighbor
wanted to try the bandsaw. He discovered that the 18 TPI blade (way
less than 1 tooth per metal thickness) running at wood speed (3000
SFPM) cut that .020 steel cleanly as fast as he could push it thru the
saw. No heat problems, no broken teeth, smooth cuts. Ear protection
strongly recommended!

Yes, I'm sure it's steel. A magnet proved it.

Now that he's discovered that, I'd better bolt my saw to the floor!
(He's a contractor, does siding every now and then.)