The service life of roller bearings is extremely sensitive to large and hard nonmetallic inclusions (NMIs), requesting the highest standards in their production. To determine the metallurgical possibilities, the effect of Al2O3 contents between 0 and 33 pct in the remelting slag was investigated by remelting a roller bearing steel in an experimental electroslag remelting (ESR) plant. Thereby, changes in the chemical composition of the materials (electrode vs ingots) and in the remelting slag during remelting, as well as the amount and composition of the NMIs prior to and after remelting, were investigated. Changes in the chemical composition can largely be explained by equilibrium reactions between the slag and the metal, thereby low Al contents in the remelted materials could only be achieved with the lowest Al2O3 contents in the slag. Furthermore, higher Al2O3 contents in the slag also lead to higher oxygen and sulfur contents in the steel as well as higher amounts of NMIs after remelting. The composition of the NMIs changed from alumina type for high Al2O3 contents to spinel type and other mixed MgO-SiO2 oxides for low Al2O3 contents. The results indicate solutions for the production of bearing steels with the lowest amounts of undesired large and hard NMIs.

中文翻译：

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渣中Al2O3含量对电渣重熔化学反应及非金属夹杂物的影响

滚子轴承的使用寿命对大而硬的非金属夹杂物 (NMI) 极为敏感，因此在生产中要求最高标准。为了确定冶金可能性，通过在实验性电渣重熔 (ESR) 设备中重熔滚子轴承钢，研究了重熔渣中 0 到 33% 之间的 Al2O3 含量的影响。因此，研究了材料的化学成分（电极与锭）和重熔过程中重熔渣的变化，以及重熔前后 NMI 的数量和组成。化学成分的变化在很大程度上可以通过炉渣和金属之间的平衡反应来解释，因此只有在炉渣中的 Al2O3 含量最低的情况下才能实现重熔材料中的低 Al 含量。此外，炉渣中较高的 Al2O3 含量也会导致钢中氧和硫含量较高，以及重熔后 NMI 含量较高。NMI 的组成从高 Al2O3 含量的氧化铝型变为尖晶石型和低 Al2O3 含量的其他混合 MgO-SiO2 氧化物。结果表明生产轴承钢的解决方案具有最少数量的不需要的大而硬的 NMI。