PURPOSE: To enhance the mechanical properties and anisotropy of steel products by predeoxidizing molten steel discharged from a refining furnace; supplying a specified amt. of a Ca-contg. material into a deep part of the steel to reduce the S content; flotation-separating Ca type inclusions; and further adding a Ca-contg. material during pouring.
CONSTITUTION: Molten steel discharged into a ladle or the like from a refining furnace is predeoxidized, and a Ca-contg. material such as Ca or Ca-Si is supplied into a deep part of the steel in an amt. above 0.05 kg as Ca/ton of molten steel/ 0.001% of S content to reduce the S content to below 0.005%. The molten steel is then agitated or degassed to flotation-separate Ca type inclusions. During pouring the steel a Ca-contg. material is added in an amt. of 0.01W0.1 kg as Ca/ton of molten steel/0.001% of S content. By this method MnS inclusion can be reduced drastically, so the anisotropy, ductility, toughness, etc. of the steel can be enhanced.
KASAMATSU YUTAKA
KOYAMA SHINJI
SOEJIMA TOSHIYUKI
KAWASAKI SHIYOUZOU
TANAKA TAKAYOSHI
KAWAI KENJI
AZUMI AKITO
