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According to the alloy elements contained, wrought aluminum and aluminum alloy can be divided into eight categories.
Pure aluminum (1000 series) contains no alloying elements and is considered heat-treatment unfortified. Because of its excellent corrosion resistance, it was originally used in chemical containers and pipelines. Due to its superior conductive properties, this series is also used for conductive rails on electric power and trams. It is easy to weld with 1100 and 4043 welding wire.
Aluminum copper (2000 series) added copper to obtain a better strength. This series is heat-treatable. Mainly used for aircraft parts, rivets and standard parts products. Most 2000 series alloys are considered unsuitable for arc welding due to their high susceptibility to hot cracking. These alloys are usually recommended for welding with 4000 series welding wire. For example, 4043 and 4145 both have lower melting points and thus reduce the possibility of hot cracking. These alloys are only partially used for welding applications.
Aluminum manganese (3000 series) is generally used in the manufacturing and construction industries to heat treat unfortified aluminum alloys. Due to the moderate strength, it is used for welding in subway, light rail, automobile, container and other industries, and has a very wide development prospect.
Aluminum silicon (4000 series) The addition of silicon lowers the melting point of aluminum and improves fluidity. Its main use is as a filler metal. The 4000 series has very good weldability and is considered a non-heat-treatable alloy. 4047 is suitable for brazing and gas welding because of its good fluidity, so it becomes the welding wire of choice for automobile heat exchanger.
Aluminum Magnesium (5000 series) After magnesium is added to aluminum, the alloy has excellent weldability, has a welded joint strength close to the strength of the base metal and is not easy to produce hot cracks. In fact, the 5000 series is the strongest of all non-heat-treatable strengthened alloys. Because of its good corrosion resistance, it is used in chemical storage vessels and cryogenic pressure vessels, as well as building structures, rail cars, automobiles, dump trucks and bridges.
Aluminum-magnesium-silicon (6000 series) has medium strength and is an alloy that can be strengthened by heat treatment. Commonly used in automobiles, pipelines, rail transit, construction and extrusion equipment. 6000 series are prone to thermal cracking to some extent. But it can also be avoided by choosing the right filler alloy. Considering crack resistance
4043 is the filler wire most often combined with this series of alloys. If the welding needs to be deformed, 5356 or 5183 is selected.
Other (8000 series) alloys of aluminum in combination with other elements (e. g., lithium) fall into this series. Most of these alloys are not commonly used, but they have good hardness and are mainly used in the aircraft industry. 4000 series welding wires can be selected for filler welding materials of these heat-treatable alloys.
There are many welding methods suitable for aluminum and aluminum alloy, and various methods have their own applications. The currently available welding methods are summarized as follows:
(1) Gas welding Gas welding is the use of gas flame (commonly used oxygen-acetylene flame) generated heat to gradually melt the connected metal surface to join together. Because the thermal power is lower than that of arc welding, the heat is more dispersed, so the welding deformation is large, the productivity is low, the weld grain is coarse, and the organization is loose. Although the equipment is simple and convenient, this method is only recommended for welding aluminum structures with small thickness and unimportant, as well as sheet butt and casting repair welding.
(2) electrode arc welding can be simple, cheap portable equipment for welding. However, the welding process of aluminum electrode is very poor, and the quality of the joint is not high. It has some applications only in occasions and repairs where the requirements are not strict.
(3) Tungsten inert gas shielded arc welding (TIG welding for short) This method is welding under the protection of inert gas (argon, helium or argon-helium mixed gas). The heat is concentrated, the arc combustion is stable, the weld metal is dense, the strength and plasticity of the joint are high, and satisfactory high-quality joints can be obtained. Therefore, it is widely used in the welding of aluminum and aluminum alloys. For thin plates and all-position welding, a tungsten pulse argon arc welding has been developed since the 1960 s. The welding deformation is small and the heat affected zone of the joint is narrow. It is especially suitable for the welding of high-strength aluminum alloys such as forged aluminum and hard aluminum.
(4) Melt inert gas shielded arc welding (MIG welding for short) As the welding wire is the electrode, it can use much larger current than TIG welding, the welding speed is fast, the heat affected zone is small, the production efficiency is higher than TIG welding, and it can weld large and thick parts, which is widely used in industry. MIG welding can also use pulse power supply, using pulse power supply average welding current is small, can be used for thin plate or all-position welding.
(5) Brazing Brazing is a method of filling the joint gap with brazing filler metal lower than the melting point of aluminum and aluminum alloy base metal to achieve connection. In the welding and resistance welding is difficult to apply the occasion has more applications. The adaptability of various welding methods to aluminum and aluminum alloys is shown in the table:

According to the different welding methods, the welding materials used are also different. Tungsten argon arc welding (TIG welding) and gas welding manual filler wire generally cut into a certain length of straight wire, automatic filling wire can also be used when the coil wire. The melting electrode argon arc welding (MIG welding) is the use of disk or barrel welding wire. Manual arc welding requires the use of electrodes. Gas welding also need to cooperate with the use of powdered gas welding flux (also known as welding powder).