PURPOSE: To improve the shape of weld beads and to improve the removability of slag by contg. specific amts. of TiO2, ZrO2 and MnO2 in the compsn. of a fused flux for high speed submerged arc welding.

CONSTITUTION: The fused flux to be used in the stage of subjecting welded structures such as steel frames for buildings, bridges or the like to high speed submerged arc welding by a single or multiple electrode method is composed of 8W20% TiO2, 1.5W12% ZrO2 in 8.5W25% total contents thereof, 0.1W1.5% MnO2, 1W15% MnO, 25W45% SiO2, 2W16% Al2O3, 12W25% CaO, 2W20% CaF2 and 1W15% MgO. The weld beads which are free from undercuts, have a wide and flat bead width and have excellent appearance are obtained under high speed welding conditions.