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<p>The effects of Ce treatment (0–0.057&#xa0;wt pct), Mg treatment (0–0.003&#xa0;wt pct), and Mg–Ce treatment on the cleanliness and microstructure of as-cast H13 steel were systematically investigated through integrated microstructural characterization and thermodynamic analysis. The results indicated that Mg–Ce treatment exhibits enhanced deoxidation and desulfurization capabilities, enabling the reduction of O and S contents to 0.0003&#xa0;wt pct and 0.0011&#xa0;wt pct, respectively. After Mg–Ce treatment, original Al<sub>2</sub>O<sub>3</sub> and MnS inclusions are transformed into Ce<sub>2</sub>O<sub>3</sub>, Ce<sub>2</sub>O<sub>2</sub>S, CeS, Ce–P–As, Ce–O–S–P–As, Mg–Ce–O–S, and Mg–Ce–O–S–P–As inclusions. Compared with Ce treatment alone, Mg–Ce treatment reduces the inclusion number density in steel from 342 to 95 per mm<sup>2</sup>. With increasing Ce content, the inclusion size initially decreases and then increases. The Mg–Ce treatment (0.0027&#xa0;wt pct Mg, 0.03&#xa0;wt pct Ce) reduces inclusion size from 1.84 to 1.31&#xa0;<i>μ</i>m. Moreover, the area fraction of primary carbides first increases and then decreases with increasing Ce content, attributed to Ce's dual effects on primary carbide precipitation. The addition of trace Ce (0.022&#xa0;wt pct) promotes primary carbide precipitation, increasing the carbide area fraction by 20.0 pct, as Ce<sub>2</sub>O<sub>3</sub> and Ce<sub>2</sub>O<sub>2</sub>S inclusions provide additional nucleation sites for VC and Mo<sub>2</sub>C carbides. However, when Ce content exceeds 0.03&#xa0;wt pct, pronounced refinement of dendritic structures occurs, which suppresses primary carbide precipitation and leads to a 33.2 pct reduction in carbide area fraction. Ultimately, the Mg–Ce treatment demonstrated simultaneous enhancement of cleanliness and refinement of primary carbides, with optimal addition levels identified as 0.0027&#xa0;wt pct Mg and 0.03&#xa0;wt pct Ce.</p>

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Effect of Mg–Ce Treatment on Cleanliness and Primary Carbides of H13 Hot Work Die Steel

  • 期刊论文

  • 发表日期：

    2025年7月14日

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  • Ji Ren,
  • Jialong Tian,
  • Zhouhua Jiang,
  • Lichao Wang,
  • Chenggang Jiang

摘要

The effects of Ce treatment (0–0.057 wt pct), Mg treatment (0–0.003 wt pct), and Mg–Ce treatment on the cleanliness and microstructure of as-cast H13 steel were systematically investigated through integrated microstructural characterization and thermodynamic analysis. The results indicated that Mg–Ce treatment exhibits enhanced deoxidation and desulfurization capabilities, enabling the reduction of O and S contents to 0.0003 wt pct and 0.0011 wt pct, respectively. After Mg–Ce treatment, original Al2O3 and MnS inclusions are transformed into Ce2O3, Ce2O2S, CeS, Ce–P–As, Ce–O–S–P–As, Mg–Ce–O–S, and Mg–Ce–O–S–P–As inclusions. Compared with Ce treatment alone, Mg–Ce treatment reduces the inclusion number density in steel from 342 to 95 per mm2. With increasing Ce content, the inclusion size initially decreases and then increases. The Mg–Ce treatment (0.0027 wt pct Mg, 0.03 wt pct Ce) reduces inclusion size from 1.84 to 1.31 μm. Moreover, the area fraction of primary carbides first increases and then decreases with increasing Ce content, attributed to Ce's dual effects on primary carbide precipitation. The addition of trace Ce (0.022 wt pct) promotes primary carbide precipitation, increasing the carbide area fraction by 20.0 pct, as Ce2O3 and Ce2O2S inclusions provide additional nucleation sites for VC and Mo2C carbides. However, when Ce content exceeds 0.03 wt pct, pronounced refinement of dendritic structures occurs, which suppresses primary carbide precipitation and leads to a 33.2 pct reduction in carbide area fraction. Ultimately, the Mg–Ce treatment demonstrated simultaneous enhancement of cleanliness and refinement of primary carbides, with optimal addition levels identified as 0.0027 wt pct Mg and 0.03 wt pct Ce.