Effect of slag on oxide inclusions in carburized bearing steel during industrial electroslag remelting

• Published in: International journal of minerals, metallurgy and materials Vol. 26; no. 3; pp. 291 - 300
• Main Authors: Li, Shi-jian, Cheng, Guo-guang, Miao, Zhi-qi, Chen, Lie, Jiang, Xin-yan
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.03.2019; Springer Nature B.V; State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China%Xining Special Steel Group, Co., Ltd., Xining 810005, China
• Subjects: Aluminum oxide; Bearing steels; Calcium oxide; Carburizing; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Corrosion and Coatings; Electrodes; Electroslag remelting; Furnaces; Glass; Ingots; Materials Science; Mathematical analysis; Melting; Melting points; Metallic Materials; Natural Materials; Nonmetallic inclusions; Slag; Surfaces and Interfaces; Thermodynamic equilibrium; Thermodynamics; Thin Films; Tribology; thermodynamics; slag; bearing steel; inclusions; electroslag remelting
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-019-1737-5

Industrial experiments with three types of slags were performed to investigate the effect of slag on oxide inclusions during electroslag remelting (ESR) process. G20CrNi2Mo bearing steel was used as the consumable electrode and remelted using a 2400-kg industrial furnace. The results showed that most inclusions in the electrode were low-melting-point CaO−MgO−Al 2 O 3 . After ESR, all the inclusions in ingots were located outside the liquid region. When the slag consisted of 65.70wt% CaF 2 , 28.58wt% Al 2 O 3 , and 4.42wt% CaO was used, pure Al 2 O 3 were the dominant inclusions in ingot, some of which presented a clear trend of agglomeration. When the ingot was remelted by a multi-component slag with 16.83wt% CaO, a certain amount of sphere CaAl 4 O 7 inclusions larger than 5 μm were generated in ingot. The slag with 8.18wt% CaO exhibited greater capacity to control the inclusion characteristics. Thermodynamic calculations indicated that the total Ca and Mg in ingots were attributed from the relics in electrode and strongly influenced by the slag composition. The formation of ingot inclusions was calculated by FactSage TM 7.0, and the results were basically in accordance with the observed inclusions, indicating that a quasi-thermodynamic equilibrium could be obtained in the metal pool.