Effect of aluminium content on the formation of inclusions in Fe–5Mn– x Al steels

Abstract

The effect of Al content on the characteristics and formation of inclusions in the light-weight Fe–5Mn–xAl steels was investigated in this study. Four synthetic steels with different Al content were produced in the laboratory. The types of observed inclusions were Al₂O_{3 (pure)}, Al₂O₃–MnS, AlN_(pure), AlN–MnS, AlON–MnS, AlON and MnS. Increasing Al content from 0.5% to 6% increased the total amount of inclusions by 2.5 times. As the Al content increased from 0.5% to 3%, the number of AlN–MnS inclusions increased significantly. Moreover, the AlN(pure) inclusions appeared in 6% Al containing steel. Thermodynamic calculations confirmed that AlN inclusions formed during cooling of the steel. It is also observed that AlN can precipitate on Al₂O₃ to form AlN + Al₂O₃ inclusions, classified as multi-phase AlON inclusions in this study. Furthermore, MnS inclusions could co-precipitate with AlN and Al₂O₃ inclusions, but it preferred to co-precipitate with AlN inclusions.