| 摘要 |
<p>PURPOSE:To restrain the quantity of non-ductile non-metallic inclusion in a steel and to produce the high carbon steel having excellent tensile strength and fatigue resistant characteristic by controlling the basicity in slag for refining and Al2O3 concn. in the CONSTITUTION:The secondary refining is executed to the high carbon steel having >0.5% C in a ladle and the quantity of Al2O3 base non-metallic inclusion as the non-metallic inclusion having poor ductility is reduced as little as possible and the tensile strength and the fatigue resistant characteristic of a wire rod in the case of working to the wire rod, etc., are improved to prevent the accident of wire-cutting during using. For this purpose, in the composition of molten slag at the time of executing the secondary refining, the basicity shown with CaO/SiO2 is adjusted to 1.2-2.0 and also, the consumption of Al as deoxidizing agent is made to be <=5g/ton of the molten steel to restrain the Al2O3 quantity in the molten slag to 0.5-2.0%. The Al2O3 quantity as the non-ductile non-metallic inclusion spoiling the workability in the molten steel is reduced, and in the case of working to the wire rod, etc., the wire-cutting, etc., caused by Al2O3 base non-metallic inclusion is prevented.</p> |
