What preparation work should be done before aluminum welding

Release time:

2022-08-12

Cleaning before welding: when welding aluminum and aluminum alloy, the oxide film and oil on the surface of the workpiece welding joint and wire should be strictly removed before welding;

1, cleaning before welding: aluminum and aluminum alloy welding, welding should be strictly removed before the surface of the workpiece welding and welding wire oxide film and oil;

1) Chemical cleaning Chemical cleaning efficiency is high, stable quality, suitable for cleaning welding wire and small size, batch production of the workpiece. The method of immersion and scrubbing can be used. Use acetone, gasoline, kerosene and other organic solvents to remove oil from the surface, use 5%-10% NaOH solution at 40℃ ~ 70℃ for alkaline washing for 3 min ~ 7 min(pure aluminum for a little longer but no more than 20 min), rinse with flowing water, then use 30%HNO3 solution at room temperature to 60℃ for pickling for 1 min ~ 3 min, and rinse with flowing water. Air dry or dry at low temperature.

2) Mechanical cleaning: when the workpiece size is larger, the production cycle is longer, and the multi-layer welding or chemical cleaning is stained again, mechanical cleaning is often used. First wipe the surface with acetone, gasoline and other organic solvents to remove oil, then directly brush with a diameter of 0.15mm ~ 0.2mm copper wire brush or stainless steel wire brush, brush until the metallic luster is exposed. Generally, it is not advisable to use grinding wheel or ordinary sandpaper for grinding, so as to avoid the sand remaining on the metal surface and entering the molten pool during welding, resulting in slag inclusion and other defects. In addition, scraper, file can also be used to clean the surface to be welded.

After cleaning, if the storage time is too long (such as more than 24 hours), it should be disposed of again.

2. Pad: Aluminum alloy has very low strength at high temperature, and the flow performance of liquid aluminum is good. When welding, the weld metal is prone to collapse. In order to ensure the penetration of welding without collapse, the welding plate is often used to support the molten pool and nearby metals. The gasket can be made of graphite plate, stainless steel plate, carbon steel plate, copper plate or copper bar. A circular arc groove is opened on the surface of the backing plate to ensure that the opposite side of the weld is formed. It can also be formed by single-side welding without backing plate, but it requires skilled welding operation or strict automatic feedback control of arc welding energy and other advanced technological measures.

3, pre-welding preheating: thin, small aluminum parts generally do not need to preheat, the thickness of 10 mm ~ 15 mm can be pre-welding preheating, according to different types of aluminum alloy preheating temperature can be 100℃ ~ 200℃, available oxygen acetylene flame, electric furnace or blowtorch heating. Preheating can reduce weldment deformation and porosity.