Why is Aluminium Difficult to Weld?

In real life, we use a lot of aluminum products, very wide, but it is generally damaged can only be repaired to buy a new replacement, I think it is not easy to be welded aluminum reasons, summarized the following aspects:

(1) aluminum in the air and welding is very easy to oxidation, the generation of aluminum oxide (Al2O3) high melting point, very stable, not easy to remove, impede the melting and fusion of the parent material, the oxide film is significant, not easy to float out of the surface, easy to generate slag, not fused, not welded through and other deficiencies. Aluminum surface oxide film and adsorption of a large amount of water, easy to make the weld pores, chemical or mechanical methods should be used before welding for strict surface cleaning to remove its surface oxide film, strengthen the protection in the welding process to prevent its oxidation. Tungsten arc welding, the use of AC power source, through the “cathode cleaning” role, to remove the oxide film, gas welding, the use of flux to remove the oxide film, in the thick plate welding, welding heat can be increased, for example, helium arc heat, the use of helium or argon-helium gas protection, or the use of large specifications of the melting electrode gas shielded welding, in the DC positive connection In the case of positive DC connection, it is not necessary to “cathode cleaning”.

(2) The thermal conductivity and specific heat capacity of aluminum and aluminum alloys are about twice as much as carbon steel and low-alloy steel. The thermal conductivity of aluminum is more than ten times that of austenitic stainless steel. In the welding process, a large amount of heat can be quickly conducted to the inside of the base metal, thus welding aluminum and aluminum alloy, in addition to the energy consumed in the melting metal pool, but also more heat needlessly consumed in other parts of the metal, this useless energy consumption is more significant than the steel welding, in order to obtain high-quality welded joints, should try to use energy concentration, power energy, and sometimes can also be used to preheat and other process measures.

(3) alloying elements are prone to evaporation, burnout, so that the performance of the weld decreases.

(4) the base metal of the base material such as deformation strengthening or solid solution aging strengthening, welding heat will make the heat-affected zone strength decline.

(5) aluminum to light, heat reflection ability is strong, solid, liquid transfer state, there is no obvious color change, welding operation is difficult to judge. High-temperature aluminum strength is very low, supporting the molten pool is difficult, easy to weld through.

Sheet Metal Chassis

Why is Aluminium Difficult to Weld?

Leave a Reply Cancel reply