Abstract: A welding process for joining aluminum materials in a horizontal welding position, without preheating, this process being highly economical and characterized by minimal environmental pollution, good strength and toughness of the welded joint, in which process the arc, as in submerged arc welding of steel plates, is covered by a flux layer and burns in a closed cavity, this process being realized by the use of a flux having a flux composition of 20-70% potassium chloride (KCl), 20-70% of an alkaline earth metal chloride, preferably calcium chloride and/or magnesium chloride (CaCl.sub.2 and/or MgCl.sub.2), 1-20% of calcium fluoride (CaF.sub.2) and preferably 1-15% of a substance capable of lowering the melting point and/or releasing gas.