METHOD FOR RAISING TEMPERATURE OF MOLTEN STEEL IN RH DEGASSING

摘要

PROBLEM TO BE SOLVED: To provide a method for raising the temp. of molten steel in an RH degassing equipment restraining the development of MnO and FeO in slag with out deteriorating the cleanliness of the molten steel. ;SOLUTION: At the time of using [wt.% Mn] for Mn concn. in the molten steel 2 before raising the temp., α(kg/min) for quantity of Al flowing into a vacuum vessel 1 calculated from a product of Al concn. in the molten steel 9 and circulating flow rate, β(kg/min) for blowing oxygen quantity from a nozzle 5 and η or oxygen efficiency, the ratio of α and η×β during time raising the temp. is in the range of satisfying formula I. However, in the case the positional height of the nozzle is ≤3m from the static molten steel 9 surface in a vacuum vessel 1 and in the case of dipping the nozzle 5 into the molten steel 9, the oxygen efficiency is η=1, and in the case the positional height of the nozzle 5 exceeds 3m, the oxygen efficiency η is shown in formula II. Formula I: α/η×β)0.625×[wt% Mn]+0.625 Formula II: η= 0.12×[the positional height of the nozzle (m)] +1.36.;COPYRIGHT: (C)1997,JPO