There has long been a need for an additive capable of solubilizing fluxing materials, desulfurizing the steelmaking charge and/or removing inclusions. This invention provides the steelmaker with this capability.
The granular alloy additive is comprised of 60% calcium and 40% aluminum by weight and has granules sized within the range -14 U.S. Standard mesh to +140 U.S. Standard mesh. It can be pneumatically or mechanically injected into molten steel.
Steelmakers use calcium to help deoxidize the molten iron and remove oxygen-containing impurities, which reduce the strength, ductility and toughness of finished products. This is accomplished through the addition of calcium silicon alloy (CASI), which encapsulates and releases its constituents in a controlled manner.
This additive can also help lower the sulfur content of molten iron to low levels and prevent clogging in ladle and tundish. It does so by transforming oxide inclusions into soft calcium aluminates and complexing sulfides into (Ca, Mn)S inclusions that do not deform to elongated stringers.
This improvement in the quality of molten steel is important to the efficiency and control of steelmaking. It also enables the production of steels with low oxygen, sulfides and nitrogen contents, improving their properties.
Calcium is an essential building block for many important industrial processes and products. Among other things, calcium oxide is used to make cement and in water treatment to control acidity. It is also used to manufacture acetylene for cutting and welding and in the production of fertilizers.
Calcium carbonate has long been used to foam steelmaking slag in electric arc furnace applications. It provides a more economical, efficient, and reproducible method of foaming slag than silicon carbide. It also does not require a balancing lime addition as do silicon-based additives, and under typical conditions it produces gas evolution that is consistent with normal slag evolution.
Silicon calcium barium is an ideal composite deoxidizer and desulfurizer, and it can improve the plasticity, impact toughness and liquidity of steel. It is suitable for use in converter steelmaking workshops as a heating agent and as an additive in the production of ductile cast iron.
The machinability of steel is a crucial aspect in its use as a raw material. A high machinability makes the steel easier to process, and lowers power consumption in machining operations. The calcium additive improves machinability by modifying the oxide inclusions in the steel. It also acts as a deoxidizer and desulfurizer for the steel.
Moreover, it can be used as a recarburizer to increase the hardness of carburized metals. It is also used by chemical manufacturers as a neutralizer, and by sewage treatment plants.
In a study on AISI P20 plastic injection mold steel, the machinability of calcium-treated and nontreated material was compared in slot milling tests with triple coated (TiN, TiCN and Al2O3) cemented carbide inserts. The results showed that the machinability of the steel treated with calcium was significantly higher than that of untreated material, without compromising its main properties.
During steelmaking, calcium carbide reacts with water to produce acetylene. This useful chemical is used in numerous applications including acid neutralization and pH modification of soil. It also has ready reactivity with sulfur making it an effective hot metal desulfurizer.
In AHSS grades, rolled inclusions may provide planes of weakness that can cause weld shrinkage strains and hydrogen accumulation at interfaces (hydrogen pressure induced cracking). Ca additions strengthen elongated sulphide inclusions and make them more isotropic thereby improving toughness.
Tire weighting of payloaders, bulldozers, graders and tractors with calcium chloride (29% solution) improves traction resulting in better pushing and pulling capacities as well as decreasing vibrations when stopping, accelerating, or hauling loads. It also helps minimize mud and dust buildup when driving over unpaved roads.
Calcium aluminate can be used in the steelmaking process as a desulfurizer and inclusion remover in electric arc furnaces. It improves the overall cleanliness of the molten steel and increases productivity. This is achieved by facilitating the solubilization of flux materials and ladle slag. It also helps prevent the formation of blowholes, which are pockets of gas that can weaken the structure of the resulting product.
Unlike fluorspar, calcium aluminate does not erode furnace and ladle linings. It is also a more cost-effective alternative to aluminum. As a result, metallurgical plants demand it as a specialty binder in secondary metallurgy.
English
Write a Message