MIG WELDING METHOD FOR ALUMINUM AND ITS ALLOY

PURPOSE:To control welding distortion and to prevent puckering by inserting an electrode wire for MIG welding and a cold wire having the same component as the electrode wire substantially into a molten pool under specific conditions in MIG welding of Al (alloy). CONSTITUTION:The electrode wire 1 made of Al (alloy) is made to a succeeding wire in the welding proceeding direction and the cold wire 2 having the same material as the electrode wire 1 substantially is made to preceding wire. The electrode wire 1 and the cold wire 2 are placed on the front end of the molten pool 3 at an insertion angle (drag angle) theta1:5-40 degree and an insertion angle (push angle) theta2:20-70 degree, respectively. The supply quantity ratio of the cold wire to the electrode wire is maintained in the range of 0.2-1.3. Namely, (the cold wire supply quantity g/min)/(the electrode wire supply quantity g/min) is made equal to 0.2-1.3. By this method, the temperature of the molten pool 3 is reduced by inserting the cold wire into the molten pool under the prescribed conditions and welding distortion is controlled by increasing the quantity of molten metal 5 and efficiency of MIG welding of Al can be improved.