Provided is a flux for use in
submerged arc welding, capable of reducing the
moisture content in the flux and the amount of diffusible
hydrogen in the
welding metal, and exhibiting favorable
welding activity, regardless of whether the
welding power source is of the
alternating current or the
direct current type. The composition of this flux for use in
submerged arc welding contains MgO in the amount of 25-35
mass%, F in the amount of 15-35
mass% when calculated as CaF2, Al2O3 in the amount of 10-25
mass%, SiO2 in the amount of 10-20 mass%, one or more of Na when calculated as Na2O, K when calculated as K2O, and Li when calculated as Li2O in the total combined amount of 0.5-6.5 mass%, Fe in the amount of 0.5-5 mass% when calculated as FeO, TiO2 in the amount of 1-5 mass%, CaO in the amount of 6 mass% or less (including 0 mass%), Mn in the amount of less than 2.0 mass% when calculated as MnO (including 0 mass%), water-soluble SiO2 in the amount of 1.0 mass% or less (including 0 mass%), water-soluble Na2O in the amount of 1.0 mass% or less (including 0 mass%), and water-soluble K2O in the amount of 0.8 mass% or less (including 0 mass%). In addition, the C content thereof is 0.2 mass% or less (including 0 mass%). Furthermore, the flux composition satisfies
mathematical formula (I), given that the MgO content is [MgO], the Al2O3 content is [Al2O3], the F content when calculated as CaF2 is [CaF2], and the TiO2 content is [TiO2].