Oxygen transport behavior and characteristics of nonmetallic inclusions during vacuum electroslag remelting

Abstract

The oxygen transport behavior and characteristics of nonmetallic inclusions during electroslag remelting (ESR) under vacuum condition were investigated by comparison with ESR under argon atmosphere. The improvement of VSR on oxygen control and refinement of inclusions was further understood. The results show that oxygen content increases from 13 ppm to 24 ppm and 18 ppm after ESR process under argon atmosphere (101325 Pa) and vacuum condition (10000 Pa), respectively. The carbon deoxidization contributes to the smaller oxygen increase when vacuum condition was applied. The complex inclusions with two-layer structure are found after ESR process, and less oxide inclusions are observed in the ingot under vacuum condition. The inclusion amount per mm2 increases after ESR process, but the maximum equivalent diameter of inclusions decreases. Due to the lower oxygen content and faster solidification rate in ESR under vacuum condition, the total area of inclusions per mm2 in the ingot are smallest and the inclusions is much finer and more uniform. The results confirm that ESR under vacuum condition is more beneficial to improve steel cleanliness.