In the steelmaking process, the decarburization reaction plays a vital role in determining both the quality of molten steel and the efficiency of the refining process.
Although its mechanism differs slightly among various steelmaking routes, the ultimate goal remains the same — to reduce the carbon content in steel to meet product standards.
Why Is Decarburization Necessary?
In most steel plants, the raw materials consist of a mixture of scrap steel, pig iron, and direct reduced iron (DRI). These materials generally contain a relatively high amount of carbon.
Without an effective decarburization process, it is impossible to meet the carbon content required for construction-grade steel or low-carbon wire rod steel.
For instance, the national standards specify that:
- For Hot Rolled Ribbed Steel Bars (rebar)— HRB335, HRB400, and HRB500 — the carbon content must not exceed 25%.
- For Hot Rolled Low Carbon Steel Wire Rods, the limits are even stricter:
Q195 ≤ 0.12%, Q215 = 0.09–0.15%, Q235 = 0.12–0.20%, and Q275 = 0.14–0.22%.
However, a traditional induction furnace (IF) lacks sufficient decarburization capability.
As a result, the steelmaker must select only low-carbon scrap, which limits raw material flexibility, raises production costs, and restricts the range of steel grades that can be produced.
SME Group’s Solution: Giving Induction Furnaces True Refining Power
To overcome this limitation, SME Group developed the IF + LOD + LRF steelmaking process, an innovative combination that significantly enhances the refining capability of traditional induction furnace systems.
The key equipment is the LOD furnace (Lance Oxygen Decarburization Furnace), which allows both top oxygen blowing and bottom Ar/CO₂ stirring.
During this stage, decarburization and dephosphorization take place effectively, transforming the induction furnace into a complete refining system.
With the IF + LOD + LRF process, steel plants can:
- Use a wider range of raw materials, including higher-carbon scrap and pig iron;
- Reduce production costs, while maintaining high steel quality;
- Stably produce wire rod and construction steel that meet or exceed national standards.
This innovation allows traditional IF-based plants to shift from a “raw-material-limited” mode to a modern, flexible, and high-quality steelmaking system.
The Further Role of Decarburization in Electric Arc Furnace (EAF) Steelmaking
In EAF steelmaking, the decarburization reaction goes beyond simple carbon reduction. It is one of the most important and energy-intensive reactions in the entire process, with multiple metallurgical benefits:
- Main source of chemical heat– Decarburization generates the majority of the chemical heat in EAF steelmaking, supporting the melting process.
- Enhances reaction kinetics– The CO gas generated stirs the molten bath, improving heat and mass transfer and eliminating cold zones.
- Shortens melting time– Proper carbon addition lowers the melting point of ferrite, helping the molten bath form faster.
- Improves yield– Carbon preferentially reacts with oxygen, minimizing iron oxidation losses and improving metal recovery.
- Promotes degassing– CO bubbles effectively remove hydrogen and nitrogen, reducing gas-related defects in steel.
- Helps remove inclusions– Bubble movement promotes the flotation of large inclusions, which are absorbed by slag.
- Supports foamy slag formation– The generated gas serves as the main source for foamy slag operation, enhancing energy efficiency and arc stability.
Conclusion
In both induction furnace and electric arc furnace steelmaking, the decarburization reaction is an essential metallurgical step that determines the efficiency, cleanliness, and quality of molten steel.
By adopting SME Group’s advanced IF + LOD + LRF steelmaking process, plants can achieve high-efficiency decarburization, flexible raw material use, and production of cleaner, high-quality steel — realizing a more sustainable and modern approach to steelmaking.
