When forging, what is the blackish gray stuff that comes off when it’s being hit with the hammer?

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So I know nothing, but I’ve been playing a lot of Skyrim and watching a lot of irl forging videos, and I’m wondering. What is that ashy substance that flakes off when the hot metal is struck? Impurities rising to the surface? Coal dust? The outer layer of metal? I’m just so curious as to what exactly it is!!

Thanks!!

In: Physics

Anonymous 0 Comments

As soon as the metal comes out of the fire it starts to react with the atmosphere. Being literally red hot means the reaction happens very quickly. Iron combines with air to create iron oxide. Carbon and other elements in the metal also form oxides or nitrides. These oxides and other products quickly forms scale on the surface of the metal. Hammering then breaks the brittle scale. Further hammering shapes the metal and any new oxides that form until the metal cools