稀土渣系电渣重熔H13钢铸锭的成分、组织及夹杂物特征

摘要：稀土(RE)微合金化是开发高品质模具钢的重要手段之一。采用稀土渣系结合电渣重熔实现H13钢铸锭的稀土添加，重点对比研究了稀土氧化铝渣系和氧化铝渣系所制备H13钢铸锭的成分、组织及夹杂物特征，揭示了稀土氧化铝渣系对于H13钢铸态组织的稀土改性作用及机制。结果表明，采用稀土氧化铝渣系或稀土氧化钙渣系均可制备稀土质量分数约0.01%的H13钢铸锭，并分别将S质量分数从电极(原料)的0.01%降低至铸锭的0.005%和0.002%。稀土氧化铝渣系的H13钢铸锭中晶界处有稀土La富集，晶内分布尺寸1~2μm的近球形稀土硫氧化物La2O2S(与基体具有4.7%的较低界面错配度)。相比氧化铝渣系，稀土氧化铝渣系将H13钢铸态组织的二次枝晶平均尺寸从109.6μm减少到84.9μm，液析碳化物和夹杂物平均尺寸从5.1μm减少到3.1μm, 从而改善稀土H13钢铸态组织的均匀性。

Composition,microstructure and inclusion characteristics of H13 steel ingot by electroslag remelting with rare earth slag

Rare earth (RE) microalloying has been developed into an important method for high quality die steels. The RE H13 steel ingtos were prepared by electroslag remelting (ESR) process with RE slag. Besides, the composition, structure and inclusion of RE H13 ingots prepared by RE added alumina slag and alumina slag were investigated. Furthermore, the RE modification effect and mechanisms of RE added alumina slag for H13 ingots were revealed. The results indicate that H13 steel ingot with RE content of calculated 0.01 wt.% can be prepared by RE added alumina slag or RE added calcium oxide slag. And the S content of calculated 0.01 wt.% in electrode (raw material) can be notably reduced to 0.005 wt.% and 0.002 wt.%, respectively. The RE H13 ingots consist La enrichment in grain boundary, as well as La2O2S with size of 1.2μm. Compared with the alumina slag, the RE added alumina slag decreases the average size of secondary dendrite from 109.6μm to 84.9μm, as well as the average size of inclusions and liquation carbides from 5.1μm to 3.1μm, which notably improves the homogeneity of H13 ingots.