Quenching an anvil in a river, with an excavator - GIF

[will52100]

Depends on where and when they were made. Probably the most common is the London pattern, wrought iron or mild steel body with a 1/2" or so thick high carbon steel surface welded on. This is mostly from around the 1800's to mid 1900's, with some cast steel ones mixed in. Now days, with advances in manufacturing, it's easier and better to just cast the whole anvil from hardenable steel. From what I've seen and researched, the most common and best way to harden anvils was a waterfall type set up. Even with that, your lucky to get martensite conversion much deeper than an inch or so. If it's an early welded anvil, only the top plate gets hardened, leaving the iron body soft. With cast steel anvils you can't cool the large mass quick enough, so you end up with a soft core. Of course alloy makes a difference, but until recent years, most early anvils had basically a simple high carbon steel face, most likely a 10xx series steel like 1075 or so. Now days you've got induction hardening, flame hardening, ect, depends on the alloy for the hardening process.