Four precautions for laser welding of aluminum alloy

The four major precautions for laser welding of aluminum alloys: Laser welding machines can indeed provide high energy density and welding speed when welding aluminum alloys, making the welding process more efficient. However, the high reflectivity and low heat absorption of aluminum alloys also pose significant challenges for welding. To avoid potential issues during the welding process, there are several key points to note:

Pre welding cleaning: The surface of aluminum alloy is prone to reflecting light, so it must be thoroughly cleaned before welding. This includes removing oil and other stains, as well as cleaning the oxide film on the metal surface. Improper cleaning may lead to oxidation reactions and even explosions during the welding process.

Chemical cleaning: For small-sized and mass-produced workpieces, chemical cleaning is an efficient and stable choice. Organic solvents such as acetone and gasoline can be used to remove oil, followed by alkaline washing with 5% to 10% NaOH solution for 3-7 minutes, followed by acid washing with 30% HNO3 solution for 1-3 minutes, and finally rinsing with flowing water.

Mechanical cleaning: For large-sized workpieces or projects with longer production cycles, mechanical cleaning is more suitable. First, wipe the surface with organic solvent to remove oil, and then use a copper wire brush or stainless steel wire brush with a diameter of 0.15-0.2mm to brush until the metallic luster is exposed. Be careful not to use grinding wheels or ordinary sandpaper to polish, in order to prevent sand particles from remaining on the metal surface and entering the molten pool during welding, resulting in defects such as slag inclusion.

Pad use: Aluminum alloy has low strength at high temperatures, and liquid aluminum has good flowability. During welding, the weld metal is prone to collapse. In order to ensure welding penetration without collapse, a backing plate is often used to support the molten pool and nearby metal during welding. The cushion plate can be made of graphite plate, stainless steel plate, carbon steel plate, copper plate or copper rod, etc. Create a circular groove on the surface of the pad to ensure the formation of the weld on the opposite side. It is also possible to form double-sided welding without adding a backing plate, but it requires skilled welding operation or advanced process measures such as strict automatic feedback control of arc welding energy.

Preheating before welding: Thin and small aluminum parts generally do not require preheating. Preheating before welding can be carried out when the thickness is 10-15mm. Depending on the type of aluminum alloy, the preheating temperature can be 100-200 ℃, and can be heated using oxygen acetylene flame, electric furnace, or spray lamp. Preheating can reduce deformation of the welded parts.

By following the above precautions, the quality and efficiency of laser welding of aluminum alloys can be effectively improved, ensuring the safety and stability of the welding process.