Carbon steel cast strip, method for producing carbon steel cast strip, and steel material

摘要

PROBLEM TO BE SOLVED: To provide a carbon steel cast slab having largely improved toughness while being capable of suppressing generation of a coarse AlOcluster, a manufacturing method of the carbon steel cast slab and a steel material containing the carbon steel cast slab.SOLUTION: A carbon steel cast slab has a composition containing, by mass%, C: 0.01% to 0.30%, Si: 0.001% to 1.5%, Mn: 0.01% to 3.0%, P: 0.0010% to 0.050%, S: 0.0001% to 0.003%, Al: 0.01% to 1.5%, t.O: 0.0001% to 0.004%, t.N: 0.0001% to 0.01%, t.Zr: 0.0003% to 0.004% and the balance Fe with inevitable impurities, 50 or more Zn oxides having an equivalent circle diameter of 50 nm to 100 nm per 1 mm, and 5 or less AlOclusters having an equivalent circle diameter of more than 10 μm per 1 mm.