Steel smelting additives with Calcium Cored Wire are powdery additive packages encapsulated in sheaths of metallic wires. They are injected into molten baths by means of specially designed wire feeders.
The injection speed has an effect on the travelling distance of the cored wire in the molten bath, but it only decreases after reaching a certain critical value.
Calcium Silicon is a potent deoxidizer and desulfurizer utilized in the steel production industry. It reduces oxygen content in molten steel by changing the shape, size and distribution of oxide and sulfide inclusions, improving fluidity, machinability and ductility of the final product.
Many techniques have been developed to add Ca to the molten steel bath. One common method is to plunge masses of metallic calcium mechanically mixed or alloyed with large amounts of non-volatile materials such as nickel, manganese and steel. These non-volatile materials act as heat sinks to slow the rate of calcium boiling. However, this method has a high temperature loss and may produce deleterious effects in the steel.
Another way to add Ca is through the cored wire process. Using this technology, a powdery additive package consisting of a deoxidizer, a desulfurizer and an alloy is pulverized into certain particle sizes and fed to the molten steel through the ladle feeding wire. This technology greatly improves the alloy yield, steel casting quality and ladle feed efficiency.
The use of calcium silicon alloy as a deoxidizer and desulfurizer in the process of molten steel smelting can greatly increase the alloy yield, reduce smelting cost, shorten the smelting time and precisely control the composition of the inclusions. It can also change the nature and form of the inclusions, improving their machanical properties (especially their fluidity and impact toughness), making it possible to cast them in the usual casting state.
A common technique for injecting calcium into the molten steel is to plunge masses of metallic calcium mechanically mixed or alloyed with large amounts of non-volatile materials. However, this leads to high temperature losses and the deleterious effects of re-oxidation cannot be avoided, even if the plunging "alloy" is melted into the liquid iron.
The present invention provides a method for carrying out the addition of calcium to the molten steel by using a cored wire consisting of different additives (de-oxidant, desulfurizer, inoculant, etc.) and low carbon steel belt with arbitrary length. This method can be used in any foundry already equipped with a machine for injection of the pocket treatment into the molten iron.
It is widely used in apricot gold, desulfurization and spheroidization of cast iron. The sheath of the core wire is made from mild steel and its diameter varies according to process requirements. It is important that the core wire is injected close to the bottom of the ladle. Otherwise, the additives lose their effectiveness due to reactions with the liquid metal.
The addition of Ca to the liquid metal can improve fluidity and cleanliness, and it can change the shape of inclusions in casting products. Ca also reduces the gas content of molten steel, which is beneficial for the continuous caster process and reduces the tendency to form porous cast structures.
The feeding speed of the core wire has a major impact on the absorption rate of calcium. If the feed speed is too fast, calcium vapor is not dissolved in the molten steel and is wasted. The injection speed must be adapted to the desired feeding depth, which depends on the process conditions and the sheath thickness.
Alloy is a metal mixture of two or more elements that has properties different from those of the pure element or elements that make it up. The elements in an alloy may be metals or non-metallic substances such as carbon, silicon and nitrogen. Alloys are used to modify the physical and chemical characteristics of steel by changing their composition or altering the shape of oxide and sulfide inclusions in the steel.
During calcium addition to the molten steel, metallic calcium quickly and violently boils in the presence of the liquid steel. This causes poor efficiency, extensive re-oxidation and inconsistent calcium effects in the molten steel.
To control the boiling, various techniques have been tried to suppress the melting of metallic calcium during injection. One of these is to plunge masses of mechanically mixed or alloyed plunging “alloys” that contain large amounts of non-volatile materials, which serve to slow the rate at which the calcium boils. These techniques reduce the boiling, but they do not completely suppress it at ladle depths that are reasonable.
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