High carbon silicon 6515 (silicon carbon alloy), as a novel composite alloy deoxidizer, possesses multiple functions of "deoxidation + carbonization + heating," and can replace traditional raw materials such as ferrosilicon powder and calcium carbide. It achieves cost reduction and efficiency improvement in converter steelmaking and alloying processes, and its composition ratio and morphological design are directly adapted to the efficiency and cost requirements of large-scale steelmaking.
The designation of HC silicon 6515 (silicon-carbon alloy) originates from its core composition of "65% silicon content + 15% carbon content":
Core components: Si 60%-70%, C 12%-18% (core functional element), impurities Al≤1.5%, S≤0.05%, P≤0.04%, Fe 10%-15%;
Physical properties: Melting point 1200-1300℃, density 2.8-3.2g/cm³, in natural blocks (10-100mm), powder, or compressed form; highly chemically active at high temperatures, possessing both reducing and carburizing properties;
Core Mechanism and Quantitative Effect
(1) Composite Deoxidation: Efficient Removal of Oxygen Impurities from Molten Steel
Reaction Principle:
Silicon Deoxidation: Si + 2FeO → SiO₂ + 2Fe, the generated SiO₂ easily floats and is removed with the slag;
Carbon-Assisted Deoxidation: C + FeO → CO↑ + Fe, CO gas stirs the molten steel, promotes the floating of inclusions, and improves the uniformity of deoxidation;
Synergistic Effect: The combined silicon and carbon deoxidation efficiency is 20%-30% higher than that of single ferrosilicon, avoiding insufficient local deoxidation;
Quantitative Effect:
With an addition amount of 0.8%-1.5%, the oxygen content of molten steel can be reduced from 80-100ppm to 35-50ppm, and the deoxidation efficiency reaches 50%-65%;
Comparison with Traditional Processes: Replacing the ferrosilicon + carbon raiser combination, the total amount of oxide inclusions is reduced by 40%-50%, and the surface defect rate of the billet is reduced from 1.2% to 0.5%.
(2) Carbon Enhancement Control: Precisely Matching the Carbon Content Requirements of Steel Grades
Mechanism of Action: Carbon elements dissolve directly in molten steel, achieving precise carbon enhancement and avoiding the problem of large fluctuations in absorption rate of traditional carbon enhancers (such as graphite powder);
Quantitative Effect:
Carbon enhancement efficiency reaches 85%-90%, and the carbon content of molten steel can be precisely controlled from 0.05% to 0.15%-0.45%, meeting the carbon content requirements of medium carbon steel (45#) and low alloy structural steel (Q355);
Comparison with graphite carbon enhancers: Carbon absorption rate is increased by 30%-40%, and the uniformity deviation of molten steel composition is ≤±0.02%, reducing the scrap rate caused by fluctuations in carbon content.
(3) Heating assistance: reducing steelmaking energy consumption
Reaction characteristics: Silicon, carbon and oxygen reactions are all exothermic reactions;
Quantitative effect: Adding 1.0% high carbon silicon 6515 can raise the temperature of molten steel by 40-60℃, reduce electrode or fuel consumption, and reduce energy consumption per ton of steel by 5%-8%, which is especially suitable for the heating requirements of converter steelmaking.
