Steel treatment with Calcium Cored Wire is used to reduce the content of harmful elements in molten steel. It can help to modify inclusions, avoid caster nozzle blockage of aluminum killed steel and prevent the formation of calcium oxide.
Cored wire can be inserted smoothly into the molten steel, which helps to ensure that calcium is released at an optimal depth. This can also help to avoid the mixing of iron powder and calcium powder.
The calcium treatment through cored wire injection can modify the nature of oxide and sulphide inclusions, prevent the clogging of casting nozzles, improve castability and purify the molten steel. This technology can also reduce the consumption of calcium in tons of steel, and avoid the introduction of harmful elements into the molten steel.
Incorporation of calcium alloy in the molten steel by spraying directly into the ladle or using calcium powder has unstable treatment effect, and is therefore not favored. However, the solid-core calcium wire, which is composed of cold rolled low carbon steel strip plus a layer of metal silicon-calcium powder, can achieve an excellent calcium addition and achieve a stable treatment effect.
Compared with the old-fashioned filler wires, solid-core calcium wire has the advantages of lower fume generation and more positive effects on technicians. It can significantly increase the welding speed, avoid slag formation, and greatly reduce the work-related pollution of welders and the environment.
With this method, the calcium that would otherwise be lost in a dusting process is efficiently injected into the molten steel. The result is a significantly better metallurgical performance than that achieved with the conventional spraying or feeding methods.
Moreover, the metal calcium used in the core of the wire is not easily oxidized and burned when entering the molten steel. This is because the solid pure calcium wire has a higher density and lower melting point than the iron powder of the cored wire.
The high-temperature cored wire can effectively modify and control the nature of the oxide inclusions in the liquid steel, thereby preventing clogging in the casting nozzles. For instance, it can transform spinels into aluminates and further convert them into low-melting-point inclusions that do not clog the nozzles. In addition, the tumbling motion of the molten steel caused by the calcium injected through the cored wire is also effective in reducing the concentration gradient of the dissolved inclusions, which can further improve the quality of the castable molten steel.
The use of cored wire injection in steel treatment allows for the deep reduction of oxygen (O) and sulfur (S) content in liquid steel, the modification of inclusions, prevention of nozzle clogging in cast aluminum killed steel, and improvement of mechanical properties. Moreover, it allows for the accurate control of calcium feeding.
Cored wire injection is a technology that has matured as one of the leading methods for performing calcium additions. It provides a higher calcium recovery and is easy to operate. It is also used in apricot gold, desulfurization, spheroidization and creeping treatment of cast iron.
Cored wire injection is a type of metal calcium alloy wire consisting of an inner core of pure solid calcium and an outer sheath of steel strip. It is extruded into different diameters and has the advantage of high tensile strength and toughness. In addition, it does not burn or oxidize when being injected into the molten steel. The sheath prevents the core material from dissolving in the molten steel, which reduces power consumption and enables the core to be positioned closer to the surface of the melt.
The calcium treatment with pure core wire avoids the mixing of iron powder and calcium powder, which is very dangerous for the metallurgical quality of molten steel. The metallurgical results are superior to standard calcium treatments (CaFe or CaSi wires).
The cored wire has an outer sheath made of cold-rolled low-carbon steel strip. The sheath is tightly wound around the core of metal calcium line, and then it is fed into the molten steel by the wire feeder.
The cored wire is injected into the molten steel at a velocity that enables it to penetrate deep into the liquid steel. This allows the calcium to be dissolved in the slag phase and to change the composition of inclusions, such as oxide micro-inclusions, oxysulfides and sulfides. This helps to reduce nozzle clogging of cast aluminum killed steel, to improve the mechanical properties of the steel, and to save energy by avoiding excessive cooling. In addition, the cored wire also prevents the formation of long strips of sulfide inclusions in the molten steel.
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