| 摘要 |
PROBLEM TO BE SOLVED: To provide a fatigue crack resistant steel plate for welding having excellent fatigue strength of a welded joint. SOLUTION: The fatigue crack resistant steel plate for welding is characterized in that: it has a composition which consists of, by mass, 0.01 to 0.10% C, 0.04 to 0.6% Si, 0.50 to 2.0% Mn,≤0.006% P,≤0.003% S, 0.003 to 0.06% Al, 0.001 to 0.10% Ti and the balance Fe with impurities and in which B and O (oxygen) as the impurities are≤0.0007% and≤0.0030%, respectively, and the value of carbon equivalent (Ceq) ranges from 0.28 to 0.65%; and a cleanliness defined by expression [(cleanliness of type A inclusions)×1+(cleanliness of type B inclusions)×3+(cleanliness of type C inclusions)×1.5], in the region between the surface of the steel plate and a position at a depth of 2 mm from the surface in a plate-thickness direction, is 0.005 to 0.1%. The steel plate can further contain one or more among≤1.5% Cu,≤1.5% Ni,≤1.2% Cr,≤1.0% Mo,≤0.1% V,≤0.10% Nb,≤0.0010% REM and≤0.0010% Mg. COPYRIGHT: (C)2007,JPO&INPIT
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