PURPOSE: To reduce swelling and dry carcking of covered flux and to improve product yield of the flux by including metallic powder which is coated with chemically stabilized inorganic oxides, into the flux.

CONSTITUTION: The welding flux contains, for instance, powder of metals such as Mg and Al and intermetallic compounds such as Fe-Si and Al-Mg, and the powder is coated with inorganic oxides of 0.01wt% or above by the total weight of the powder. As inorganic oxides to be coated on the surface of the metallic powder, generally alumina is the most frequently used.