| 摘要 |
A steel product contains, by mass%, C : 0.45 to 0.60%, Si : 0.01 to 0.15%, Mn : 0.20 to 0.60%, S : 0.012% or lower, Al : 0.015 to 0.040%, Ti : 0.005 to 0.050%, B : 0.0005 to 0.0050%, N : 0.010% or lower, O : 0.0010% or lower, and balance being Fe and unavoidable impurities. Limitations are provided to allowable maximum sizes per each sort of contained non-metallic inclusions and the number per unit area thereof. This steel may contains one kind or two kinds or more of Cr: 1.00% or lower, Mo: 0.50% or lower and Ni: 1.50 or lower. |
