Aluminum alloy body welding technology and welding matters

Aluminum alloy body welding technology and welding matters

(1) Aluminum alloy has a strong affinity with oxygen

It is very easy to combine with oxygen in the air to generate dense and strong alumina film, the thickness of which is about 0.1μm. The melting point is as high as 2050℃, far more than that of aluminium and aluminium alloy, and the density is great, about 1.4 times that of aluminium. During the welding process, the aluminium oxide film prevents good bonding between metals and can easily cause slagging. The oxide film also attracts moisture, which can lead to the formation of pores in the weld. All these defects will reduce the performance of the welded joint. In order to ensure the quality of the weld, the surface of the weld must be strictly cleaned of oxides before welding, and to prevent re-oxidation during the welding process, the molten metal and the metal at high temperatures are effectively protected, which is an important feature of aluminium and aluminum alloy body welding. Specific protection measures are: the use of mechanical grinding or chemical methods D40 to remove oxides from the workpiece bevel and surrounding parts before welding; the welding process should be protected by qualified protective gas (e.g. 99.99% Ar).

(2) The thermal conductivity and specific heat of aluminium alloys are large

The thermal conductivity and specific heat capacity of aluminium and aluminium alloys are very large. In the welding process, a large amount of heat energy is rapidly conducted to the collective metal interior, in order to obtain high quality welded joints, a heat source with concentrated energy and high power must be used. 8mm and above thick plates need to adopt preheating and other process measures in order to achieve the melt welding process.