Reducing macro segregation of high carbon steel in continuous casting bloom by final electromagnetic stirring and mechanical soft reduction integrated process

Abstract

The influence of final electromagnetic stirring (F-EMS) combined with mechanical soft reduction (MSR) on reducing macro segregation has been investigated in order to improve inner quality of high carbon steel bloom with 1 wt.% carbon. A 2D heat transfer model was developed to predict the solidification process of bloom by taking into account thermo-physical properties which were obtained by experiments. The predicted surface temperature and shell thickness were verified by infrared temperature and nail shooting measurement results, respectively. In addition, roll-gap calculation model was established by a segmented slope method to calculate the proper soft reduction zone and determine the distribution of total reduction amount. The optimum F-EMS implement position and soft reduction zone with the goal of minimum macro segregation of high carbon steel bloom were theoretically determined by the heat transfer model associating with high temperature tensile test. The industrial research results showed that macro segregation has been significantly improved by the optimum combination with F-EMS and MSR processes, and the risk of center negative segregation and internal cracks could be avoided by modifying F-EMS implemented position and the distribution of total reduction amount. Besides, compared with the combination of mold electromagnetic stirring (M-EMS) and F-EMS processes, the reasonable center solid fraction of bloom at the F-EMS implemented position in F-EMS and MSR integrated process was much lower.