PRODUCTION OF CARBON STEEL HAVING GOOD COLD WORKABILITY

摘要

PURPOSE:To improve cold workability by subjecting a molten steel to a vacuum degassing treatment under specific conditions then blowing a powder REM alloy together with gaseous Ar or N2 under prescribed conditions to the molten steel thereby reforming the resultant product of deoxidation and flotation. CONSTITUTION:A molten steel is subjected to a vacuum degassing treatment prior to addition of an REM alloy to decrease the T.O in the molten steel to <=30ppm. The powder REM alloy is then blown together with inert gaseous Ar or N2 at 0.5-2.0kg/T-S to the molten steel to stir positively the molten steel. The grain size of the REM alloy is made <=500mum an the inert gas is blown at 0.5-4.0Nl/T-min. for 3-15min. The non-metallic inclusions of oxide type are decreased, are forcibly floated and separated and are removed together with slag by the above-mentioned method. The cold workability is thus improved.