| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel having high strength, and also excellent in fatigue strength by achieving reduction of the number and reduction of size of inclusions in the steel, and a production method enabling the steel to be produced while suppressing an increase in a production cost.SOLUTION: There is provided the steel sheet containing, by mass%, C:0.30% to 0.70%, Si:2.50% or less, Mn:1.00% or less, Cr:1.00% to 4.00%, Mo:0.50% to 3.00%, V:1.00% or less, Al:over 0.010% to 0.050% or less, O:0.0015% or less and the balance Fe with inevitable impurities, having a tensile strength of 1700 MPa or more, an elongation of 8.0% or more, an equivalent circle diameter maximum value of inclusions in the steel of 15 μm or less and the number of inclusions having equivalent circle diameter of 1 μm or more of 110/mmor less. |
