LOW-OXYGEN CLEAN STEEL AND LOW-OXYGEN CLEAN STEEL PRODUCT

摘要

Low-oxygen clean steel is provided containing C, Si, Mn, P, and S as chemical components, and further containing, by mass %, 0.005% to 0.20% of Al, greater than 0% to 0.0005% of Ca, 0.00005% to 0.0004% of REM, and greater than 0% to 0.003% of T.O, wherein the REM content, the Ca content, and the T.O content satisfy 0.15≦REM/Ca≦4.00 and Ca/T.O≦0.50, nonmetallic inclusions which have a maximum predicted diameter of 1 μm to 30 μm measured using an extreme value statistical method under the condition in which a prediction area is 30,000 mm2, and contain Al2O3 and REM oxide are dispersed in the steel, an average proportion of the Al2O3 in the nonmetallic inclusions is greater than 50%, the REM is one or two or more of rare-earth elements La, Ce, Pr, and Nd, and the steel is Al-deoxidized steel or Al—Si-deoxidized steel.

主权项

1. A low-oxygen clean steel containing C, Si, Mn, P, and S as chemical components, and further containing, by mass %, 0.005% to 0.20% of Al, greater than 0% to 0.0005% of Ca, 0.00005% to 0.0004% of REM, and greater than 0% to 0.003% of T.O,
wherein the REM content, the Ca content, and the T.O content satisfy the following Expressions 1 and 2, nonmetallic inclusions which have a maximum predicted diameter of 1 μm to 30 μm measured using an extreme value statistical method under the condition in which a prediction area is 30,000 mm2, and contain Al2O3 and REM oxide are dispersed in the steel, an average proportion of the Al2O3 in the nonmetallic inclusions is greater than 50%, the REM is one or two or more of rare-earth elements La, Ce, Pr, and Nd, and the steel is Al-deoxidized steel or Al—Si-deoxidized steel,
0.15≦REM/Ca≦4.00  Expression 1,Ca/T.O≦0.50  Expression 2.