Sulfur aluminum calcium iron is used as a core wire for steelmaking. It can improve the quality of molten steel by deoxidation, desulfurization and arsenic removal. It can also reduce the consumption of calcium and improve the slag liquid level of reducing line.
It can stably control the content of oxides and sulfur in steel, modify inclusion morphology and significantly improve through-thickness impact toughness and plasticity. It can also eliminate nozzle clogging in continuous casting.
The calcium added with cored wire reacts with oxygen and sulphur in the molten steel. This deoxidant reaction reduces the liquidus temperature of the inclusion phases, thus opening up the castability window of the steel. This is because the inclusions lose their brittleness as they re-solidify due to the lower liquidus temperature.
The addition of the calcium alloy also changes the morphology of the inclusions. Its surface tension effect alters the spherical shape of the inclusions, reducing their number and size. This is beneficial for the slag removal and purification of molten steel.
It was found that the arsenic concentration in molten steel decreased after being treated with calcium. This was because the calcium reacted with oxygen, sulfur and arsenic to form composite inclusions. However, it did not react with phosphorus. The reason was that the oxygen and sulfur concentrations in equilibrium with calcium were very low. This is why it is important to use protective slag blankets, inert gas or refractory shrouded nozzles when using cored wire.
Generally, the sulphur aluminum calcium iron is used for the deoxidation of molten steel in order to avoid oxygen and sulfur consumption. It is also suitable for the removal of arsenic. However, it is necessary to control the concentration of oxygen and sulfur in molten steel to a narrow range. Otherwise, the added calcium will react with oxygen and sulfur and consume them. It is therefore necessary to pre-deoxidize the molten steel through aluminum powder.
The line scan image and surface scanning of the arsenic removal product reveals that the inclusions are mainly collision-type Ca3As2 surrounded by inclusions of calcium aluminate (xCaO-yAl2O3). These arsenic-containing inclusions are likely to be formed in the process of dearsenication treatment through adsorption and collision of the calcium aluminate on the oxides. This change rule implies that the amount of adsorption and collision can be controlled in the smelter through adjusting the additions of calcium alloy, electromagnetic swirl stirring, etc.
A specialized alloy powder is used to produce cored wire. It has a high melting point and low thermal conductivity compared to steel, thus providing good heat transfer properties. It also has an abrasion resistance. This makes it ideal for use as a composite deoxidizer and desulfurizer.
Moreover, it has a good chemical compatibility with other materials such as silica, magnesia, and carbonates. Using it in the production of cast iron helps to reduce the amount of sulphur and oxygen in the melt. It is also a cost-effective material for the cored wire industry.
It is possible to achieve much higher calcium yields in a liquid metal than in the case of conventional pocket treatment, especially with a lower liquid steel feed rate and a thicker slag layer. This is due to the more efficient absorption of the calcium by the slag, and the lower reaction with oxygen and sulphur. The injection depth of the cored wire also has a significant impact on the yield.
Using a core wire to introduce calcium into molten steel requires careful design to ensure that the calcium is not consumed by oxysulfides or sulfur. It is also essential that the injected calcium does not interfere with the deoxidation process or cause the formation of inclusions in the cast product.
In addition to lowering the calcium oxide content, utilizing Sulfur Aluminum Calcium Iron can help improve the quality of castings by minimizing inclusions. This is especially important when casting lamellar or ductile iron, as these types of iron require a larger number of nucleation sites to properly solidify.
The use of Sulfur Aluminum Calcium Iron can also reduce the presence of arsenic in the final cast product by adsorption and collision with oxygen, sulfur, and sulfides. This can also improve the efficiency of a desulfurizer or deoxidizer in reducing the oxygen and sulfur content in the molten steel.
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