METHOD OF PRODUCTION OF PIPE STEEL Russian patent published in 1998 - IPC

FIELD: ferrous metallurgy, particular, production of pipe steels resistant to corrosion in hydrogen sulfide medium. SUBSTANCE: the offered method includes steel making in electrical furnace, tapping of metal into ladle with cutoff of slag, refining in course of tapping and steel finishing on furnace-ladle system by introduction into melt of aluminium in form of two portions, silicomanganese, lime, fluorspar with melt stirring by blowing-through with argon, subsequent modifying with additive introduced into melt. Modifying mixture consists of aluminium, ferrovanadium and silicocalcium taken in ratio of (1.5-3.0):(27.0-34.5):(15-30.0) in the amount of 2.9-4.5 kg per ton of steel. In so doing, introduction into melt of one portion of aluminium, silicomanganese, lime and fluorspar is effected in form of refining mixture in ratio of (1.0-1.5):(15.0-22.5):(1.0-3.0), respectively, in the amount of 18.28 kg per ton of steel. Blowing with argon is carried out with intensity of 0.05-0.35 cu.m per ton in minute for each kilogram per ton of mixture. The other portion of aluminium is introduced continuously into melt at the ratio ensuring maintenance of aluminium in melt within 0.010-0.030% up to attaining the content of sulfur in metal not in excess of 0.005%, then, modification is accomplished. EFFECT: higher efficiency. 3 tbl