Steelmaking
lastmod 2025-02-04created 2023-02-167 edits
Steelmaking refers to the manufacture of steel. Pig iron from the blast furnace contains about 4% carbon and impurities such as silicon, phosphorus, and manganese. This pig iron is hard but brittle, so it is used only for casting. To make it into steel, the carbon in the pig iron must be reduced and the impurities removed. Because reduction by coke in the blast furnace goes too far and too much carbon gets mixed into the iron, this time the iron must instead be oxidized to reduce the carbon, while impurities such as silicon and phosphorus are also oxidized and removed. This is called steelmaking, and there are two representative steelmaking methods: using an open hearth furnace and using a converter.
Steelmaking process
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- Iron production methods and processes (blast furnace / electric furnace / FINEX)
The steelmaking process is the core process of ironmaking, in which the various impurities contained in the molten iron are burned off in the electric furnace to turn it into molten steel with the properties of steel.
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- Electric arc furnace
- The electric furnace uses electric heat: current is passed through the electrodes, which are good electrical conductors, and the scrap is melted by the heat of the arc generated between the scrap and the electrodes. The main raw material, scrap iron, is charged into the electric furnace, an arc forms between the electrodes and the scrap, and once the scrap is melted by that heat, oxygen is blown in for oxidizing refining; the resulting slag is removed, and various slag-forming agents are added to produce steel with good reducibility.
- Refining
- The molten steel from the electric furnace is received in a ladle, and arc heat is used to adjust the chemical composition to suit continuous casting and to remove various impurities.
- Continuous casting
- A process that pours refined molten steel directly into molds to continuously produce billets, the intermediate material for steel products. The molten steel is moved by ladle to the casting floor of the continuous caster and poured into the tundish, where inclusions in the molten steel are separated by flotation, and the molten steel is poured into the mold to produce billets.
Steel Industry
| Basic | ||
| Iron production (Ironworks) | Smelting | Bloomery (produces sponge iron), Blast furnace (produces pig iron) (Cold blast, Hot blast, Anthracite iron), Direct reduced iron, Korean: 제선 (Iron making), Molten Iron |
| Secondary | Wrought iron (via Finery forge or Reverberatory Puddling Furnace), Cast iron (via Cupola furnace or Induction furnace) | |
| Steelmaking (Steel mill) | Primary (Pre-1850) | Pattern welding, Crucible steel (Damascus steel), Tatara furnace, Cementation process |
| Primary (Post-1850) | Bessemer process, Open hearth furnace, Electric arc furnace, Basic oxygen process | |
| Secondary | Electro-slag remelting, Vacuum arc remelting, Argon oxygen decarburization | |
| Heat treatment methods | Annealing | Low hydrogen, Short circuit |
| Hardening/Case-hardening | Ausforming, Boriding, Carbonitriding, Carburizing, Cryogenic, Ferritic nitrocarburizing, Induction, Nitriding, Precipitation, Quench polish quench | |
| Tempering | Austempering, Martempering | |
| Cryogenic treatment (Deburring, Deflashing, Hardening), Differential heat treatment, Decarburization, Forming gas, Post weld heat treatment, Quenching, Superplastic forming | ||
| E.T.C | ||