1 LF Furnace Atmosphere
The LF furnace performs molten steel refining treatment under normal pressure, and the water-cooled furnace cover can serve as a sealing function for separating air. When heated, the graphite electrode reacts with oxides such as FeO and MnO in the slag to form CO gas, which increases the reducing property of the furnace gas. In addition, the graphite electrode also reacts with oxygen in the steel to form carbon-oxide, thereby enabling LF. The oxygen content in the furnace atmosphere is reduced to ensure strong reducibility of the furnace atmosphere. The molten steel can be further deoxidized, desulfurized and removed by non-metallic inclusions under reducing conditions to improve the quality of the molten steel.
According to the different requirements of steel grades, the reducing agent silicon carbide powder can be added to the furnace in batches to maintain a strong reducing atmosphere in the furnace, speed up the refining speed, and at the same time reduce electrode oxidation and reduce electrode consumption.
2 Argon Stirring
1）The main functions of argon blowing are:
a. Foaming, air washing effect: reducing the content of [H], [N] in the molten steel, and further removing oxygen in the steel;
b. Stirring effect: detachable [S], remove inclusions, slag inclusion, so that temperature and composition are uniform;
c. Protection: Argon gas escapes from the molten steel and covers the surface of the molten steel to avoid secondary oxidation of the molten steel;
Argon Stirring Mechanism
Since the effect of argon blowing agitation in the metallurgical refining process of the refining furnace directly affects the refining effect, the refining effect is related to factors such as argon blowing pressure, argon flow rate, processing time, and bubble size produced.
Therefore, choosing a reasonable argon blowing system can not only achieve the expected metallurgical effect, but also produce good economic benefits.
3 Submerged Arc Heating
The LF furnace adopts three-phase AC power supply, and uses three electrode arcs to heat the molten steel. When heating, the electrode is inserted into the slag layer by submerged arc operation, the arc has small thermal radiation to the cladding wall, and the age of the package is improved, and the thermal efficiency of heating is high, and the heat utilization rate is high. Ok, therefore, it is necessary to ensure good submerged slag.
The graphite electrode reacts with the oxide in the slag, and as a result, not only the unstable oxide in the slag is reduced, the reduction property of the slag is improved, and the alloy yield is also improved. Another result is that a large amount of CO gas is generated, which enhances the reducing atmosphere in the furnace and further improves the quality of the molten steel.
The slag amount of the submerged arc slag is generally 1 to 1.5% of the molten steel, and the CaO-CaF2 system or the CaO-Al2O3 system is commonly used.
4 White Residue Refining
The LF furnace smelting is white slag operation, and the white slag has strong reducibility. This is the result of good reductive atmosphere and argon stirring interaction in the LF furnace. Generally, the slag is 2 to 3% of the amount of molten steel, passing through white. Slag operation reduces the oxygen, sulfur and inclusions in the steel.
Post time: Mar-18-2022