Thermodynamic analysis of the coupling reaction of manganese, silicon, magnesium, calcium, aluminum with oxygen in the boron-containing melt based on iron

The thermodynamic analysis of the interaction of boron dissolved in liquid steel with components of metal melt, such as oxygen, aluminium, calcium, magnesium and carbon is carried out. The authors managed to develop a technique of drawing component solubility surfaces in liquid boron-bearing steel based on calculations of liquidus lines and surfaces for binary and ternary oxide phase diagrams with B 2O 3. It was established that manganese and silicon can not block oxidation of boron introduced into steel. In this case boron interacting with oxygen, manganese and silicon forms liquid oxide (slag) non-metallic inclusions. Calcium is not an effective protector of boron. Addition of alloys containing aluminium and magnesium can prevent oxidation of the introduced boron and thus enables to stabilize the production technology of boron-modified steels. With one thousandth of percent of aluminium and magnesium the possibility of boron dissolved in steel with retained oxygen is excluded. In order to retain a sufficient amount of “effective boron” in steel it is necessary to develop an effective system of denitration of steel by introducing nitride forming elements and vacuum degassing.