Abstract
It is proved that the amount of non-metallic inclusions extracted from middle-rim-zone and from bottom-core-zone is related with the amount of gas evolved during solidification and rimming action.
The amount of non-metallic inclusions in middle-rim-zone becomes less as the amount of evolutional gas from rimming steel ingots gets larger.For example, the cleanest rim-zone of ingot is obtained at the carbon content of 0.07 to 0.09%, at which the amount of evolution gas is the largest.The amount of inclusions in bottom-core-zone is not always corelated with the gas amount, but it is found out that there is a certain range of combination of carbon content and additional amount of aluminum for the least amount of inclusions.
