Aluminum welding methods
Almost all kinds of welding methods can be used for welding aluminum and aluminum, but aluminum and aluminum alloy adaptability of the various welding methods, various welding methods have their own applications. Gas welding and SMAW method, simple equipment, easy to operate. Gas welding can be used for repair welding for welding low-quality aluminum sheet and castings. SMAW can be used for repair welding of aluminum alloy castings. Inert gas shielded arc welding (TIG or MIG) method is the most widely used aluminum and aluminum alloy welding methods. Aluminum and aluminum alloy sheet can be used tungsten to exchange argon arc or tungsten pulse argon arc welding. Aluminum and aluminum alloy thick plates can be used tungsten helium arc welding, argon-helium mixed tungsten arc welding, MIG welding, pulsed MIG welding. MIG welding, pulsed MIG welding applications more widely (argon or argon / helium gas mixture)
Preparation before welding
A clean up before welding: aluminum and aluminum welding, welding should be strictly clear the workpiece weld and wire the surface oxide film and greasy;
1) chemical cleaning chemical cleaning and high efficiency, stable quality, apply to clean-up wire and size, mass production of the workpiece. Available dip both France and scrub method. Available organic solvents acetone, gasoline, kerosene and other surface degreasing, alkaline cleaning using 40 ℃ to 70 ℃, 5% to 10% of NaOH solution 3 min ~ 7 min (pure aluminum a little longer but no more than 20 min), mobile water rinse , and then at room temperature to 60 ℃ 30% HNO3 solution pickling 1 min to for 3 min, mobile water rinse, and dry or low-temperature drying.
2) Mechanical cleaning: the larger the size of the workpiece, longer production cycle, multi-pass welding or chemical cleaning after contamination, often by mechanical cleaning. Wipe the surface of organic solvents such as acetone, gasoline and oil, followed by the direct use of a diameter of 0.15 mm ~~ 0.2 mm copper wire brush or stainless steel wire brush, brush to the exposed metallic luster so far. Generally should not use the wheel or ordinary sandpaper sanding to avoid sand stay in the surface of the metal bath to produce welding defects such as slag. Also available scraper, file clean up to be welded surface.
Clean up after such long time storage (eg, more than 24 h) should be reprocessed.
2, plate: Aluminum low strength at high temperatures, the flow properties of liquid aluminum, welding, weld metal is prone to staying phenomenon. In order to ensure penetration without collapse of the plate, welding is often used to lift up the bath and around the metal. Plate can be used graphite plates, stainless steel, carbon steel plate, copper or copper. The plate surface to open an arc-shaped groove, in order to ensure the weld negative molding. Plate can also add side welding shape, but requires welding proficiency or take strict automatic feedback control and other advanced technological measures for arc welding energy.
3, preheat: thin, small pieces of aluminum generally without preheating, thickness 10 mm to 15 mm before welding, preheating, according to the different types of aluminum preheat temperature of 100 ℃ to 200 ℃, the available oxygen an acetylene flame, an electric stove or torch heating. Preheat allows welding to reduce the deformation to reduce the porosity and other defects.
Weld treatment
(1) post-weld clean-up after welding to stay in the weld and the nearby remnants of flux and welding slag will destroy the passive film of the aluminum surface, and sometimes corrosive aluminum parts should be clean. Shape requirements can be a general workpiece with hot water washed or steam blowing brush simple way to clean up. Require complex shape aluminum parts in hot water using a stiff brush, wash, and then about 60 ℃ ~ 80 ℃ and the concentration of 2% to 3% chromic acid aqueous solution or potassium dichromate solution dip 5 min ~ 10 min, and scrub with a stiff brush, then washed in hot water washing, drying oven, or hot air drying, natural drying.
(2) the general post-weld heat treatment of aluminum containers do not require post-weld heat treatment. |
