Evolution of Al₂O₃ inclusions by magnesium treatment in H13 hot work die steel

Abstract

To investigate the evolution mechanism of Al₂O₃ 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 Al₂O₃ inclusions in H13 die steel were modified to MgO·Al₂O₃ and MgO after Mg treatment. Two types of MgO·Al₂O₃ 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 Mg-containing and high Mg-containing H13 die steel were comprehensive discussed. The different reaction mechanisms result in the different of the core of the MgO·Al₂O₃ inclusion.

Keywords:

• Magnesium
• Inclusions
• Long-range gravity
• Thermodynamics
• H13 die steel

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (Grant No. 51374022 and 51504019) and China Postdoctoral Science Foundation (Grant No. 2014M560047) and China Postdoctoral Science Foundation (Grant No. 2014M560047).