Thermodynamics on formation of low melting point inclusions at different temperatures in 60Si2MnA spring steel

Equilibria between 60Si2MnA molten spring steel and such low melting point inclusions as MnO-SiO₂-Al₂O₃ inclusions, CaO-Al₂O₃-SiO₂ inclusions and CaO-Al₂O₃-SiO₂-15% MgO inclusions were thermodynamically studied by the thermodynamic software FactSage at three different temperatures of 1 873, 1 823 and 1 773 K. On the basis of these calculations, the compositions of the liquid steel were determined when these low melting point inclusions formed at the different temperatures. Simultaneously, it was also discovered by comparison that low temperature is more beneficial to fulfill the control of the low melting point inclusions under the condition of low soluble oxygen content. The soluble aluminum content for the formation of CaO-Al₂O₃-SiO₂-15% MgO inclusions is much higher than that for the formation of CaO-Al₂O₃-SiO₂ inclusions, and it is easily controlled in actual production.