| 摘要 |
PROBLEM TO BE SOLVED: To provide flux for high heat input submerged arc welding with which weld metal having excellent toughness can be obtained, and a method for producing a high heat input submerged arc welded joint. SOLUTION: The flux contains, by mass to the total content of the flux, 20 to 45% atomized iron powder having a N content <=0.0030%, or further contains B of 0.03 to 0.30% in terms of B, or further contains one or more kinds selected from Mo of 0.2 to 2.0% in terms of Mo and Nb of 0.02 to 0.15% in terms of Nb. Using this flux, steel having a base metal composition of, by mass, <=0.006% Ti and <=0.012% Nb is joined by high heat input submerged arc welding in which heat input is >=150 kJ/cm, so that the amount of intergranular ferrite to be produced is reduced, and weld metal having high toughness can be obtained.
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