Abstract：In order to study the effect of magnesium treatment on inclusions in steel， the aluminum deoxidized 30CrNi2MoVA steel was treated with NiMg alloy. Total three groups of experiments were carried out. The content of magnesium in the steel at the end was less than 0.001%， 0.010% and 0.014%， respectively. The experimental results indicated that magnesium treatment had good effect on deoxidization， desulfurization and dephosphorization. It could effectively make the inclusions in steel disperse and fine， and meanwhile change the type and composition of inclusions. With the increase of magnesium content， the average equivalent diameter of inclusions in steel decreased from [?2.0×10－6 m]to[?1.0×10－6 m，] and the proportion of inclusions with equivalent diameter less than[?1.5×10－6 m]increased from 84.04% to 93.65%. However， when the magnesium content increased to 0.014%， a small amount of large inclusions began to appear in the steel. Combining the experimental results with the thermodynamic calculation and analysis， it could be found that with increasing magnesium content in the steel， the types of inclusions in steel changed from Al2O3 to Al-Mg-O system， MgO and Mg-O-S system. As the magnesium content in steel was further increased， some fine pure MgS and Mg-O-S-P inclusions in the steel were observed.
2020, Vol. 38 
