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

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 ìm. Inclusions smaller than 3 urn take nearly 75% of the total inclusions observed in each ingot. Inclusions observed in ESR ingots are pure A1N as dominating precipitates and some fine spherical Al_2O_3 inclusions with a size of 1 (ìm or less. It is also found that protective gas operation and slag deoxidation treatment during ESR process have significant effects on the number of inclusions smaller than 2 ìm but little effects on that of inclusions larger than 2 urn. Thermodynamic calculations show that A1N inclusions are unable to precipitate in the liquid metal pool under the present experimental conditions, while the precipitation of A1N inclusions could take place at the solidifying front due to the microsegregation of Al and N in liquid steel during solidification.