Submerged arc welding method with multiple electrodes for steel material

A multiple-electrode submerged arc welding method for steel, comprising:

• spacing one of the interelectrode distances to 23 mm or more on a surface of the steel;
• spacing the remaining interelectrode distances to 20 mm or less on the surface of the steel;
• supplying current to a first electrode using a direct current power source;
• supplying current in which the current density of the first electrode is 250 A/mm2 or more and the current density of a second electrode is 150 A/mm2 or more;
• subjecting steel to multiple-electrode submerged arc welding with three or more electrodes;
• and
• forming a semi-one molten pool that is a molten pool partially constricted and shallow at a bottom surface of the molten pool and has a shape like a bottle gourd such that two front and rear molten pools are fused together.