The effects of different Ca and S contents of steel on the modification of endogenous Al₂O₃ inclusions were studied in the laboratory. Three Ca levels (35, 20, 10 ppm) and two S levels (30, 20 ppm) were studied. An automated SEM-EDS system was used for the characterization of inclusions. It was found that the quantity of inclusions in steel increases with the amount of Ca and S contents in the melt. The mechanism of inclusion modification had been discussed based upon the obtained results and thermodynamics. Furthermore, a parameter named ‘dimensionless Ca’ was introduced, which can be used to estimate the extent of modification of inclusions based upon the Ca content of the steel. This parameter was validated against industrial heats.

室内研究了不同Ca、S含量钢对内源性Al ₂ O ₃夹杂物变质的影响。研究了三种 Ca 水平（35、20、10 ppm）和两种 S 水平（30、20 ppm）。使用自动 SEM-EDS 系统来表征夹杂物。发现钢中夹杂物的数量随着熔体中Ca和S含量的增加而增加。基于所得结果和热力学讨论了夹杂物改性的机理。此外，还引入了一个名为“无量纲Ca”的参数，该参数可用于根据钢的Ca 含量估计夹杂物的变质程度。该参数已针对工业加热进行了验证。