METHOD OF OBTAINING LOW-PHOSPHOROUS CONTENTS IN MEDIU-AND HIGH-CARBON STEELS IN A BOTTOM-BLOWN OXYGEN STEEL-MAKING FURNACE

摘要

1415535 Low-phosphorus steel by bottom blowing USS ENGS & CONSULTANTS Inc 5 Dec 1972 [6 Dec 1971 13 Nov 1972] 56110/72 Heading C7D Medium and high carbon steels are produced directly by bottom blowing with oxygen-containing gas having entrained lime, using an overall lime rate (L 0 ) averaged over the whole blow of 0.09 - 0.16 Ib./ftSP3/SP of oxygen, with the average rate (L 1 ) over the first half of the blow being less than L 0 and the rate (L 2 ) over the second half being greater than L 0 . Preferably L 1 is at least 10% less greater than L 0 and L 2 is at least 10% greater than L 0 , while the end-point temperature of the heat does not exceed [3030 - 100 (%C)]‹F, where (%C) is the desired final carbon content. Other preferred features include a blowing rate such that (%C) is achieved within 10 minutes, and, when producing steel with (%C) greater than 0.35%, a lime rate over the final 40% of the blowing time which is at least 1.5 x L 0 , or, when starting from iron containing more than 0.05% S, a blowing rate at least equal to L 0 over the first 25% of blowing time.