| 摘要 |
PROBLEM TO BE SOLVED: To provide a carbon steel slab in which crystal grains can be stably refined in γ solidified steel, and excellent in various properties.SOLUTION: Provided is a carbon steel slab having a composition containing prescribed amounts of C, Si, Mn, P, S, T.Al, Ca, Zr and T.O, and the balance Fe with inevitable impurities, and satisfying 0.2≤[%Ca]/[%T.O]≤0.8 and [%Zr]≥4×[%Ca]×(3.4×[%T.Al]+1.0), in which inclusions made of ZrO-CaO based composite oxide are dispersed, the average composition of the inclusions satisfies 0≤(%AlO)≤18, 0.04≤(%CaO)/(%ZrO)≤0.22, where, in the inclusions, the average value of the cross-sectional area ratio in the CaO concentration is 11% or lower is 67% or higher, and the inclusions having a size in a major axis of 1 to 10 μm are dispersed within the range of 10 to 500 pieces/mmby piece density.SELECTED DRAWING: None |
