Before aluminum alloy welding, before welding should be carefully eradicated workpiece weld mouth and wire appearance of the oxide film and oil, aluminum in the air and oxygen action, in the aluminum plate surface production of a very thin layer of dense natural oxide film, than other metal oxide film generated fast and thick much, and thus prevent the air in the harmful gas and moisture further corrosion, played a role in protecting the aluminum plate, but affect the aluminum plate selding, eradication quality directly affects the quality of welding technology and joints, such as the tendency of weld porosity and mechanical properties. Chemical cleaning and mechanical finishing are often used in two ways.
1) Chemical cleaning. Chemical cleaning is highly efficient, stable quality, suitable for finishing welding wire and scale is not large, batch production of workpieces. Available dipping method and scrubbing method two. Available gasoline and other organic solvents appear to oil, with 40 ℃ ~ 70 ℃ 5% ~ 10% NaOH solution alkali wash 3 min ~ 7 min, activity water rinse, followed by room temperature to 60 ℃ 30% HNO3 solution acid wash 1 min ~ 3 min, activity water rinse, air dry or low temperature drying.
2) In the workpiece scale is large, long production cycle, multi-layer welding or chemical cleaning and then stained, often choose mechanical finishing. First, gasoline and other organic solvents wipe test the exterior to remove oil, followed by direct brushing with a diameter of 0.15 mm ~ 0.2 mm copper wire brush or stainless steel wire brush, brush to reveal the metal luster stop. Usually we should not use abrasive wheels or general sandpaper grinding, to avoid sand particles on the metal surface, welding into the molten pool of slag and other shortcomings. Alternatively, scrapers, files, etc. can be used to organize the appearance to be welded.