Calcium silicon treatment agent is used as a deoxidizer and desulfurizer in the steel making process. It improves cleanliness and ductility by modifying the composition, size, and shape of oxide and sulphide inclusions.
It is injected into the liquid steel bath by core wire injection metallurgy. This allows it to be absorbed deep inside the steel melt, without the influence of trim additions and argon blowing.
The refractory material of core wire is a silicon calcium alloy powder, which is wrapped by a steel strip and processed by a cored wire machine. The cored wire technology is an out-of-furnace refining method, enabling the steel to be added in the form of a liquid rather than as a solid lump. The advantage of this is higher recovery and a more stable liquid metal.
Deoxidation is one of the main functions of the calcium silicon treatment agent. It improves the quality of the molten steel, reduces oxygen content, makes nonmetal inclusion sex change and eliminates metallurgical effects such as dangerous trace elements.
There are two types of deoxidation: simple and complex. The simple type is when a single element is used; for example, Si deoxidation. The complex type is when a mixture of elements such as Si-Mn-Al deoxidation is used. In the latter case, oxides of various shapes are formed and their activities differ.
Desulfurization is the process of removing sulfur from liquid steel. The removal of sulfur can improve steel cleanliness and help manufacturers meet strict quality standards for their final products.
The use of calcium cored wire makes it easy to add the necessary amount of calcium to liquid steel and ensure a consistent level of desulfurization. This can help minimize the production of harmful sulfur dioxide gases during processing and end-use applications, which in turn promotes air quality and a safer working environment for workers.
The solid-core pure calcium wire is wrapped by a steel strip, making it hard to break and leak the core powder. The solid calcium core wire helps make the feeding operation smooth and saves time. The high-density core wire also reduces the number of threading times, reducing labor intensity and improving the productivity of workers. The meterial calcium content of the cored wire can be adjusted according to different processes. It is especially suitable for the apricot gold, desulfurization, spheroidization and creeping treatment of cast iron.
Inclusion modification is a key process for reducing directional anisotropy of molten steel. The process modifies the size, composition, and structure of oxides, sulfides, and silicates in the steel. It also makes the inclusions more globular, which helps reduce directional anisotropy. This can help improve ductility, strength, and toughness of the steel.
In the conventional method, the calcium metal is added to molten steel by spraying or through cored wire feeding. The use of cored wire allows for more controlled, precise additions and can prevent contamination.
The cored wire is made of a low-carbon steel strip wrapped around the metal calcium and fed into the molten steel through a wire feeder. This allows the calcium to be passed from the core into the molten steel, and can significantly decrease the burning loss of metal calcium. The cored wire also minimizes the transfer of other elements present in the calcium powder to the molten steel, such as iron.
A calcium silicon alloy can serve as a deoxidizer in the converter or ladle because of its high specific gravity and low melting point. However, throwing pure solid calcium into the molten steel may cause combustion and fail to reach the upper and deeper positions of the molten steel to react.
During the leaching process, heterogeneous exothermic reactions took place in both the UFG and the CG samples. As a result, foaming bubbles were observed in both samples and intensive sparks were visible above the solution surface.
EBSD analysis showed that both samples had weak textures with the equiaxed austenite grains with some annealing twins. However, the CG sample displayed a stronger texture than the UFG one. Post-mortem nanoindentation results were analyzed based on the grain interior and grain boundary locations of the plastic zone. A higher KAM value indicated a higher strain in the indented area. The average KAM value on the UFG grain boundary was higher than that on the CG one.
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