A product made of aluminum and other alloy elements. It is usually processed into casting products, forging products, foils, plates, belts, pipes, bars, profiles, etc., and then made by cold bending, sawing, drilling, assembling, coloring and other processes. The main metal element is aluminum. Some alloy elements are added to improve the performance of aluminum.

Almost all kinds of welding methods can be used to weld aluminum and aluminum alloy, but the adaptability of aluminum and aluminum alloy to various welding methods is different, and each welding method has its own application occasions. Gas welding and electrode arc welding are simple in equipment and convenient in operation. Gas welding can be used for repair welding of aluminum sheet and castings with low welding quality requirements. Welding rod arc welding can be used for repair welding of aluminum alloy castings. Inert gas welding (TIG or MIG) is the most widely used welding method for aluminum and aluminum alloy. The aluminum and aluminum alloy sheet can be TIG welding or pulsed TIG welding. The aluminum and aluminum alloy thick plate can be welded by tungsten helium arc welding, argon helium mixed tungsten gas shielded welding, fusion gas shielded welding and pulse fusion gas shielded welding. GMAW and pulsed GMAW are more and more widely used (argon or argon / helium mixture)

1. Cleaning before welding: during the welding of aluminum and aluminum alloy, the oxide film and oil stain on the welding junction of workpiece and the surface of welding wire shall be strictly removed before welding;

1) chemical cleaning chemical cleaning has high efficiency and stable quality, which is suitable for cleaning welding wire and small size workpieces in batch production. There are two methods available: immersion and scrubbing. The oil can be removed from the surface of acetone, gasoline, kerosene and other organic solvents, washed with 5% - 10% NaOH solution at 40 ℃ ~ 70 ℃ for 3 min ~ 7 min (the time of pure aluminum is a little longer but not more than 20 min), rinsed with flowing water, then rinsed with 30% HNO3 solution at room temperature to 60 ℃ for 1 min ~ 3 min, rinsed with flowing water, air dried or dried at low temperature.

2) mechanical cleaning: mechanical cleaning is often used when the workpiece size is large, the production cycle is long, multi-layer welding or chemical cleaning is followed by contamination. First, wipe the test surface with acetone, gasoline and other organic solvents to remove oil, and then directly brush with 0.15mm-0.2mm diameter copper wire brush or stainless steel wire brush until the metal luster is exposed. Generally, it is not suitable to use grinding wheel or ordinary sandpaper to polish, so as to avoid sand particles left on the metal surface and slag inclusion and other defects when entering the molten pool during welding. In addition, scraper and file can be used to clean the surface to be welded.

After cleaning, if the storage time is too long (if more than 24 hours), it shall be reprocessed.

2. Base plate: the strength of aluminum alloy is very low at high temperature, the flow performance of liquid aluminum is good, and the weld metal is prone to collapse during welding. In order to ensure penetration without collapse, backing plate is often used to support the weld pool and nearby metal. The base plate can be graphite plate, stainless steel plate, carbon steel plate, copper plate or copper bar, etc. An arc-shaped groove is opened on the surface of the base plate to ensure that the reverse side of the weld is formed. One side welding and two sides forming without base plate is also allowed, but advanced technological measures such as skilled welding operation or strict automatic feedback control of arc welding energy are required.

3. Preheating before welding: thin and small aluminum parts generally do not need preheating. Preheating before welding can be carried out when the thickness is 10 mm ~ 15 mm. According to different types of aluminum alloy, the preheating temperature can be 100 ℃ ~ 200 ℃, which can be heated by oxygen acetylene flame, electric furnace or blowtorch. Preheating can reduce the deformation and porosity of weldment.

(1) the residual flux and welding slag left in the weld and nearby after welding will damage the passivation film on the aluminum surface and sometimes corrode the aluminum parts, which should be cleaned up. Simple shape and general workpiece can be cleaned by hot water washing or steam blowing. For aluminum parts with high requirements and complex shapes, they shall be brushed with a hard brush in hot water, then immersed in an aqueous solution of chromic anhydride or potassium dichromate solution of about 60 ℃ ~ 80 ℃ with a concentration of 2% ~ 3% for 5min ~ 10min, washed with a hard brush, washed in hot water, dried in an oven, or dried with hot air, or dried naturally.

(2) post weld heat treatment is generally not required for aluminum containers.

Recycle purchase recycle

Aluminum is one of the most important nonferrous metals. Due to its good properties (small density, good plasticity and formability) and easy recovery, pure aluminum and aluminum alloy have become important basic materials in household appliances. It is widely used in the Remaking of hot parts, conductive parts and other parts of household appliances. The recycling of waste aluminum has become the most important part of the recycling of non-ferrous metals. Its energy consumption and recycling cost are much lower than the production of raw aluminum (about 10%).