| 摘要 |
PROBLEM TO BE SOLVED: To provide steel improved in fatigue characteristics in high strength steel having tensile strength of >=1,500 MPa and to provide a producing method therefor. SOLUTION: The fatigue characteristics of high strength steel of >=1,500 MPa is improved by allowing the same to have a composition containing, by mass, 0.2 to 1.3% C, 0.01 to 3.0% Si and 0.2 to 3.0% Mn and, if required, containing other elements, controlling the carbon equivalent (ceq) shown by the following formula to >=0.8, and also, reducing the amount of hydrogen released when heated from room temperature to 500 deg.C to <=0.3 ppm: Ceq=C%+ Si%/15+Mn%/10+Cr%/11+Mo%/7+V%/5+Ni%/45+Cu%/45.
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