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Rimmed steel, killed steel and semi-killed steel
- Dec 14, 2017 -

The steel ingot can be divided into rimmed steel, killed steel and semi-killed steel according to the different deoxidation degree of the steel.

Rimmed steel is a steel without deoxidation or full deoxidation. After the molten steel is injected into the ingot mold, the carbon and oxygen will react in the molten steel when the temperature fall and a large amount of CO gas is produced, which is called "boiling" steel. The Rimmed steel ingot does not occur concentrated shrinkage, so the cutting head rate of the rimmed steel ingot is lower than that of the killed steel.The segregation of the rimmed steel is large and the composition is uneven.

Before pouring the molten steel is fully deoxidated, molten steel is calm, no "boiling", it is called killed steel. It has compact structure, high strength, less segregation and uniform composition. The cost of killed steel is higher than that of rimmed steel because it increases the cutting head rate due to the formation of a central cavity. For the mechanical properties and other of higher requirements and special requirements of the steel, all cast killed steel ingot.

The degree of deoxidation between killed steel and rimmed steel is called semi-killed steel. because the deoxidation is not complete, in the pouring process there is still a slight "boiling" steel, known as semi-killed steel. It is smaller than the central shrinkage of the killed steel, the cutting head rate is low, the segregation of the rimmed steel is less, and the mechanical property is good.