Characteristics of inclusions in high-Al steel during electroslag remelting process

Cheng-bin Shi1,2), Xi-chun Chen3), and Han-jie Guo1,2) 1) State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China 2) School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China 3) Research Institute of High Temperature Materials, Central Iron and Steel Research Institute, Beijing 100081, China

摘 要：The characteristics of inclusions in high-Al steel refined by electroslag remelting （ESR） were investigated by image analysis, scanning electron microscopy （SEM）, and energy-dispersive spectrometry （EDS）. The results show that the size of almost all the inclusions observed in ESR ingots is less than 5 μm. Inclusions smaller than 3 μm take nearly 75% of the total inclusions observed in each ingot. Inclu-sions observed in ESR ingots are pure AlN as dominating precipitates and some fine spherical Al2O3 inclusions with a size of 1 μm or less. It is also found that protective gas operation and slag deoxidation treatment during ESR process have significant effects on the number of in-clusions smaller than 2 μm but little effects on that of inclusions larger than 2 μm. Thermodynamic calculations show that AlN inclusions are unable to precipitate in the liquid metal pool under the present experimental conditions, while the precipitation of AlN inclusions could take place at the solidifying front due to the microsegregation of Al and N in liquid steel during solidification.

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