I had a fun learning experience planned out, but then realized that I didn't know if it was even possible.
First, the main question: Can one forge heavily rusted (not quite falling apart, but past "100% pitted surface") "mystery steel" using a wood/charcoal forge? If so, are there any special considerations I need to worry about?
Just guessing, but I'd reckon (at least) one of 3 things would happen: 1. The hot carbon could actually Reduce the rust back into un-oxidized Iron/Steel; 2. The rust (which probably trapped some sort of dirt/minerals) would just turn to Scale and fall off (or get pounded into the base Iron as Inclusions if I didn't remove them properly); or 3. The Iron would just fall apart (from heat expanding all the rusted micro-fissures) before I could forge them back together.
Here's the "why do you ask?": I wanted to do a "Building From 'Scratch'" learning experience. Walking along the beaches in my area (along an inland sea with partial access to Pacific Ocean), I noticed just how much metal there really is "just laying there". Most of this is in the form of very large bolts (1 inch diameter by 18 inches long or 2.5 by 45 cm) going through old "barrier logs" or broken dock pieces, or bits of Rebar protruding from pieces of broken concrete. Occasionally, one might find an old gate post with several large nails and a rusted/twisted hinge still on it.
I'm fairly handy in the woods, but I'm no Les "Suvivorman" Stroud, so I plan on "cheating" on several aspects: having a tent, a cooler/backpack of food, a fishing pole, a canoe, and probably even my truck parked nearby. xxxx, I'll probably do this over several "visits"/camping trips that might be weeks or months apart. I know of some REALLY rural/desolate islands/beaches within easy reach of a few good "car camping" locations.
As for the Forging aspects, which is the point of this particular exercise, I want to keep it as basic as possible: Only start with the "tools" I'd normally have on me any time while hiking/boating: a pocket knife, a lighter, a multi-tool (includes small hacksaw and general purpose "SawzAll" blades), length of "paracord", Magnesium fire-starter/"FireSteel", a leather belt, a roll of electrical tape, and of course my clothes. Those are actually all part of my "EveryDay Carry"... Everything else, including stock metal, will have to be found/scrounged "on-site".
My "Mk 1 Forge" will be a driftwood campfire in pit in the beach sand, mostly surrounded by large rocks. If I found some natural clay to make basic cobblestone/cob, maybe make it slightly "beehive"-/"volcano"-shaped to hold in the heat and create a natural draft. Additional draft would be from hand-fanning the fire with something large and flat, maybe a piece of scrap plywood that floated ashore.
"Mk 1 Anvil" will probably be a Granite boulder with a fairly flat top, or maybe a smoother Chert stone on top of said Granite boulder.
"Mk 1 Smithing Hammer(s)" will probably be a roughly "grapefruit"-sized rock, either held in my hand or maybe tied between some sticks. Probably multiple rocks unless I manage to find a good one with a rounded end (AKA, "Ball-Peen Hammer"), a flattened end (umm... 'normal' "Sledgehammer"), and maybe even a straight "line" edged part (like a "Cross-Peen Hammer").
Basic idea is to "start with (next to) nothing and make tools to make slightly better tools to make better tools and see how far I can get with only items found on a stretch of beach and some woods." That said, considering almost all my metal would have floated through salt-water, if one can't really Forge heavily rusted steel/iron, my plan is broken from the start.
Brian H.