Calcium treatment is mainly used for aluminum killed steels to decrease the volume fraction of oxide and sulphide inclusions through deoxidation and desulfurization and control their composition, morphology, and distribution. It also reduces nozzle blockage in continuous casting and solves other problems caused by non-metallic inclusions.
It is injected into the liquid steel using cored wire to modify the inclusion morphology. This improvement improves hot workability and enables better machinability.
In the process of aluminum killed molten steel continuous casting, calcium treatment can effectively modify the nature and quantity of inclusions in liquid steel. It can convert the oxide inclusions that cause clogging of the casting nozzles into liquid ones, which greatly improves the quality of the cast metal.
Solid calcium cored wire has the advantage that it can be fed into molten steel directly, so as to reduce the burning loss of metal calcium in molten steel and achieve a more complete absorption rate of calcium metal. It also prevents the harmful elements from powder packet cored wire from entering molten steel, which can have an adverse effect on the quality of the steel.
The feeding speed of the cored wire has a large influence on the absorption rate of the calcium. In order to ensure a high and stable absorption rate, it is important to adjust the feeding speed in a reasonable range.
The encapsulated pure metal calcium wire in steel sheath (called cored wire) is injected into the liquid steel using a high-pressure wire injection system. The resulting reaction between Ca and the O and S in the steel is far more intense than when the same amount of Ca is added as a lump. This results in a higher recovery of Ca in the steel, and also in less dust and fumes in the work place.
The core-spun wire can be fed into molten steel quickly with the help of a core wire feeder, which reduces nozzle blockage. It can be used for deoxidation, desulfurization, inclusion control, and alloying in continuous casting of aluminum killed steel and steel sheet.
It can also change the shape of the inclusions and improve the castability of molten steel. This can lead to a better quality of steel and lower refining costs. In addition, it can significantly improve the economic efficiency of smelting plants.
Calcium is used as a desiliconizer in the steelmaking process. It can modify the shape, size and structure of inclusions in molten steel, remove sulfide stringers, and eliminate directional anisotropy during hot working. It can also partially change the nature and form of easily oxidizable elements, non-metal inclusions and trace elements, thereby improving the quality of molten steel and reducing alloy consumption and energy consumption.
The method of adding calcium to molten steel with cored wires is more effective than spraying or dusting. It can improve the efficiency of calcium treatment by making the contact between Ca and molten steel as intimate as possible. It can also be injected deep into the molten steel bath using this method, which allows for more uniform reaction rates.
When using solid core calcium wires, it is important to choose the proper feeding position. The feeding point should be located away from the argon blowing circle to avoid an adverse impact on the quality of the molten steel. It is also advisable to use core wires with higher purity of metal calcium to achieve a better effect.
As a powerful deoxidizer and desulfurizer, calcium can help to modify the shape of inclusions. It can convert sulphide and oxide inclusions into globular ones that do not cause nozzle blockage. This process is called inclusion control. It can greatly improve steel quality, reduce alloy consumption and shorten smelting time.
To make this possible, the core wire is wrapped with a layer of metal calcium to prevent oxygen from getting into the steel. It is then pressed and stuffed through professional cored wire machine. The compaction and stuffing process should be in compliance with standards to ensure that there is no leakage of powder.
In the process of forming a Calcium Cored Wire, a gatherer is used to locate the steel strip and calcium line; a format roll is installed to avoid calcium line vibration and damage to the arc; and a hold-down head and welding rolls are used to keep the wire in place during insertion into the steel ladle.
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