For welders, aluminum's reputation as a "moody" metal did not arise out of thin air. The physical properties of aluminum create a number of difficulties that simply do not exist when working with steel, and without understanding these features, it is much more difficult to obtain a reliable seam.
The oxide film is the main source of difficulties
The main problem is that aluminum is instantly coated in air with a thin oxide film, the melting point of which is significantly higher than the melting point of the metal itself underneath. As long as this film is not destroyed, the welding arc simply cannot melt the base metal normally — it is necessary either to mechanically remove the oxide layer before welding, or to use equipment and a mode capable of destroying the film right during operation. Orgplex should specify which equipment and technology are used for a specific task. The approach may vary depending on the thickness of the part and the requirements for the quality of the seam.
If the oxide film is not completely removed, minute inclusions remain in the seam, which reduce the strength of the joint and can cause a hidden defect that is invisible during visual inspection, but manifests itself with subsequent mechanical stress on the structure.
Thermal conductivity and risk of deformation
Aluminum dissipates heat much faster than steel, which means that the welder has to supply more energy to maintain a stable weld pool - heat is rapidly dissipated throughout the workpiece instead of concentrating precisely in the seam area. When welding aluminum, this creates a risk of local overheating and subsequent deformation of the part, especially noticeable on thin sheets, where temperature differences at different points of the workpiece quickly lead to metal warping.
An additional complication is that aluminum does not change color as clearly as steel when heated. It is visually difficult to determine the moment when the metal is about to start melting, which requires the welder to have much more experience with this particular material in order not to burn the workpiece.
Porosity of the seam and other typical defects
Another common problem is the porosity of the weld caused by the absorption of hydrogen by molten aluminum during welding. When the metal cools, the hydrogen does not have time to completely exit and forms small pores inside the seam, reducing its strength and tightness. To minimize this risk, it is important to thoroughly clean the workpiece before welding and use dry, moisture—free consumables - even a small amount of moisture on the metal surface can cause porosity of the finished seam.