Decarburization

From cast iron to steel
''Cast Iron isn't really usefull by itself: it's very strong but also very brittle and you cannot work with it. We can produce it easily but its saturated with carbon... Meanwhile, steel is also iron, but with less carbon in it. Currenlty we are making steel by taking pure iron and adding carbon to it with charcoal but its slower to produce and requires a lot of manual forging to produce while Cast Iron can be mass produced with blast furnaces. Therefore it would make steel production much easier if we could master a way to make steel out of Cast Iron by removing the extra carbon instead of making it by adding carbon to pure iron.''

Potential Requirements
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