系统研究了Ce微合金化H13热作模具钢中一次碳化物的析出机理及热稳定性。首先通过SEM以及夹杂物自动分析系统观察Ce微合金化H13钢中夹杂物的二维形貌、类型、数量及尺寸；进一步利用非水溶液电解法观察Ce微合金化H13钢中一次碳化物的三维形貌；随后在不同的加热温度下保温1 h研究一次碳化物的热稳定性；最后利用Factsage 7.2热力学软件计算一次碳化物的析出机理以及热稳定性。结果表明：Ce能够有效地与钢液中的O、S、P、As元素反应生成对应的夹杂物；一次碳化物的二维形貌为长条状而三维形貌为片状，两者之间差别较大；富Ti、V碳化物首先析出，随后作为富V碳化物的形核核心促进其析出，一次碳化物的三维尺寸达到50 μm；富Ti、V碳化物的热稳定性明显高于富V碳化物，当加热温度达到1250 ℃时，富Ti、V碳化物刚开始溶解但依然存在，而富V碳化物已经完全溶解；经过加热处理后，一次碳化物的三维平均尺寸降低到10 μm左右；Factsage 7.2的理论计算结果与实际观察结果基本一致。较高的加热温度可以一定程度上降低Ce微合金化H13钢中一次碳化物的危害，但不能完全去除。

Ce microalloyed H13 hot die steel is widely used in manufacturing hot extrusion and die casting mold of magnesium-aluminium alloy because of its excellent combination of hot strength and impact toughness. The C content in Ce microalloyed H13 steel is approximately 4% (mass fraction), and the alloy elements content such as Cr, Mo, V et al are about 8%. Therefore, it is easy for primary carbide to precipitate during the solidification of the molten steel due to the segregation of alloy elements. Most researchers study the precipitation mechanism of primary carbide in the two-dimensional perspective. A few people are involved in the three-dimensional morphology of the primary carbide, especially the thermal stability of the primary carbide in the three-dimensional perspective in the Ce microalloyed H13 steel. Therefore, the precipitation mechanism and thermal stability of the primary carbide were systematically studied in this work. First, the SEM and inclusion automatic analysis system were used to analyze the morphology, number density and size of the inclusions in Ce microalloyed H13 steel. The three-dimensional morphology of the primary carbide in sample was observed after electrolyzed in a non-aqueous solution. The voltage was 20 V, the electrolysis time was about 3 min and the electrolyte was composed of 1% tetramethylammonium chloride, 10% acetylacetone, and 89% methanol (volume fraction). Three samples were heated to 1150, 1200 and 1250 ℃ for 1 h to investigate the thermal stability of the primary carbide. Finally, Factsage 7.2 software was used to calculate the precipitation mechanism and thermal stability of the primary carbide. Elemental Ce can effectively react with O, S, P and As elements to form the corresponding Ce-O, Ce-S and Ce-P-As inclusions. There is a huge difference between the two-dimensional and three-dimensional morphologies of the primary carbide, the two-dimensional morphology is strip and the three-dimensional morphology is irregular flake. Ti-V-rich carbide precipitates first, and then acts as the nucleation core of V-rich carbide. When the heating temperature reaches 1250 ℃, the V-rich carbide has completely dissolved, and the Ti-V-rich carbide begins to dissolve. The three-dimensional morphology of the wrapped Ti-V-rich carbide is completely exposed after the V-rich carbide disappears completely. The Ce-O inclusion is formed before solidification, and the primary carbide precipitates at the end of the solidification of molten steel. As the Ce content in molten steel increases, the stability diagram of Ce₂O₂S and Ce-S increases gradually. The precipitation temperature of Ti-V-rich carbide is approximately 1360 ℃, and the V-rich carbide starts to precipitate at about 1200 ℃. The calculated results are keeping well with the experimental observations. The damage of primary carbide in Ce microalloyed H13 steel can be partly reduced by higher heating temperature, but cannot be completely removed.