Effect of electropulsing treatment on solidification behavior of spring steels in a continuous casting mold simulator

Abstract

An electropulsing-assisted mold simulator technique was developed to investigate the effects of a pulsed electric voltage on the quality of spring steels during continuous casting by analyzing the mold flux film, shell surface profile, shell microstructure and inclusion distributions. The results revealed significantly increased crystallization fraction of the mold flux film from 61.2% to 75.3% and finer crystalline phase morphology in the case of electropulsing treatment. The surface of the initially solidified shell could be effectively healed, resulting in smoother shell surface profiles with higher pulsed voltage from 0 to 30 V. Furthermore, an increase in the pulsed voltage from 0 to 30 V resulted in finer dendritic structures during solidification with decreasing secondary dendrite arm spacing from the values of 17.6–32.2 to 9.7–15.0 µm in the direction of shell side toward melt side. In addition, an area scan analysis of inclusions in the as-cast spring steel samples showed that the number of MnS inclusions in the size range of 2.0–4.0 µm gradually decreased from 836 to 114 and the number of Al2O3 inclusions in the same size range decreased from 144 to 39, as the voltage increased from 0 to 30 V.