King Tut's dagger--a blade of meteroritic iron

[Timo Nieminen]

Originally Posted by Roland_M

It is absolutely impossible to forge cold iron. One can hammering the steel until it is hot, but one cannot forge steel at room temperature! Otherwise one would destroy the crystalline structure of the steel or iron.

Put the iron on an anvil, and hit it with a hammer. If it is distorted past the plastic limit, you've changed its shape, and you can forge it. You have to hit it harder than if hot-forging, but it can be done.

I've done it; other people have done it. It is absolutely possible. A simple example: https://www.youtube.com/watch?v=N66-n3FJ5Vw

Originally Posted by Roland_M

Otherwise one would destroy the crystalline structure of the steel or iron.

It isn't a single crystal; it's made up of many, hopefully very small, crystals. This kind of polycrystalline structure can be distorted, so it isn't an impossible problem. (This distortion of the crystal structure is how we can distinguish cold-forged objects from hot-forged objects.)

It does lead to work-hardening, which (if you don't stop and anneal the piece) will limit how much you can work it, especially how thin you can make it.

These two points (needs more force to deform, work-hardening) plus not being able to weld as part of the process are why, for general purpose forging, you hot-forge. But hot-forging generally being better doesn't mean that cold-forging is impossible. If you lack fuel, it might be the only option. If you can start with stock that doesn't need to be worked much to reach its final shape, then it can be a good option even today (forming steel cold in a metal press, panel beating, cold-peening rivets and sword tangs are examples of this).

I haven't tried cold-forging with annealing, so can't comment on effect from experience. In principle, it should work.

Cold-forging, with intermediate annealing, is the natural way that a redsmith/coppersmith who knows nothing of iron will try to forge iron, since it's the way that copper and copper alloys are forged.