| 摘要 |
PURPOSE: A high heat input submerged arc welding seam in which a welding metal having superior toughness is obtained even when welding a steel product by high heat input submerged arc welding having 150 kJ/cm or more of welding heat input, a method for manufacturing the seam, and steel wire and flux for welding used in the seam are provided. CONSTITUTION: In a submerged arc welding seam which is welding bonded by high heat input submerged arc welding having a welding heat input of 150 kJ/cm or more, the submerged arc welding seam is characterized in that a welding metal of the welding seam comprises 0.03 to 0.15 wt.% of C, 0.10 to 1.00 wt.% of Si, 0.70 to 2.50 wt.% of Mn, 0.003 to 0.030 wt.% of Ti and 0.0050 wt.% or less of N, and a produced amount of grain boundary ferrite in the welding metal is 15.0 area% or less. In a method for manufacturing a submerged arc welding seam which is welding bonded by high heat input submerged arc welding having a welding heat input of 150 kJ/cm or more, the method for manufacturing the submerged arc welding seam is characterized in that a welding metal of the welding seam comprises 0.03 to 0.15 wt.% of C, 0.10 to 1.00 wt.% of Si, 0.70 to 2.50 wt.% of Mn, 0.003 to 0.030 wt.% of Ti and 0.0050 wt.% or less of N, and a produced amount of grain boundary ferrite in the welding metal is 15.0 area% or less. The steel wire for high heat input submerged arc welding comprises 0.03 to 0.10 wt.% of C, 0.0035 wt.% or less of N, 0.40 wt.% or less of Si, 1.00 to 2.50 wt.% of Mn, 0.030 wt.% or more Ti and a balance of Fe and inevitable impurities, wherein Ti/N is 15 to 50. The flux for submerged arc welding comprises 20 to 45 wt.% of atomized iron powder for the total amount of flux, wherein the atomized iron powder contains 0.0030 wt.% of N.
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