Control of Ca addition for improved cleanness of low C, Al killed steel

摘要

In this work, heat trials (14 heats made on two sequences) were conducted to identify the minimum Ca addition possible for preventing submerged entry nozzle clogging and for improving the steel Cleanness. These trials were conducted on two sequences, the first one aimed at reaching the minimum Ca addition practically possible and the second aimed at stabilising this addition level. Evaluation of the results was carried out using metallographic microscope observation and SEM/EDX analysis. It was found that submerged entry nozzle clogging was successfully prevented by decreasing the amount of Ca addition from 0.095 to 0.06 kg Ca/ton steel. Moreover, it was possible to identify the effect of such addition level on converting alumina inclusions to globular Ca-aluminate and reducing the CaS inclusion formation range from 4-41 to 0.05-7.61 percent .