To investigate the evolution mechanism of Al 2 O 3 inclusions after Mg treatment in H13 die steel, the determination of inclusions characteristics and thermodynamic calculation were carried out in the present study. The results showed that irregular and cluster Al 2 O 3 inclusions in H13 die steel were modified to MgO•Al 2 O 3 and MgO after Mg treatment. Two types of MgO•Al 2 O 3 were detected after Mg treatment. The long-range gravity between the MgO-containing inclusions is weaker than that of the MgO-free inclusions. The long-range gravity between the inclusions decreases with the increasing of Mg content of the steel. The evolution mechanisms of inclusion in low Mgcontaining and high Mg-containing H13 die steel were comprehensive discussed. The different reaction mechanisms result in the different of the core of the MgO•Al 2 O 3 inclusion.

No abstract