One client has a lovely, perfectly healthy looking sugar maple in his yard maybe 35-40years old. No obvious defects, solid looking trunk. Apparently struck by a snowplow years ago, killing about 1/3 of the trunk which rotted away. At least he was kind enough to tell me that there's about 4 bags of concrete in the tree now! I'd never have guessed.Metal, ha. Try concrete, that blunts chain really fast.
I actually met a guy that "saved" a tree I took down once by filling it with concrete. It didn't work.
They do make such a saw but it spins much slower than an abrasive, about half the rpm and half again as much HP.The right kind of carbide should work, especially in a full house (cutter per DL) design, and patience letting the saw do the work at whatever pace it wants. They make non abrasive metal chop saws that have a carbide tipped blade, looks just like a circular saw blade used for wood, but has a lot more teeth, and it can easily cut through steel hundreds of times.