Before welding the aluminum alloy box, the first thing we need to do is to prepare. Let's explain in detail the preparation work for aluminum box welding.
1. Choose the welding wire for aluminum box welding, usually using 301 pure aluminum welding wire and 311 aluminum silicon welding wire.
2. Select the welding method and parameters, usually using the left welding method, with the welding torch and workpiece at a 60 ° angle. When the welding thickness is above 15mm, the right welding method is used, and the welding torch and workpiece are at a 90 ° angle.
3. Before welding aluminum alloy boxes, chemical or mechanical methods are used to strictly clean the surface oxide film on both sides of the weld groove.
Mechanical cleaning can use pneumatic or electric milling cutters, as well as tools such as scrapers and files. For thinner oxide films, a 0.25mm copper wire brush can also be used to polish and remove the oxide film. After cleaning, welding should be carried out immediately. If the storage time exceeds 4 hours, it should be cleaned again.
4. Analyze the material characteristics of aluminum and aluminum alloys in aluminum box welding
Aluminum is a silver white light metal with good plasticity, high conductivity, and thermal conductivity, as well as the ability to resist oxidation and corrosion. Aluminum is prone to oxidation and produces a thin film of aluminum oxide, which can easily generate inclusions in the weld seam, thereby disrupting the continuity and uniformity of the metal and reducing its mechanical and corrosion resistance.
5. Analysis of Welding Difficulties of Aluminum and Aluminum Alloy Materials in Aluminum Box Welding
Easy to oxidize. In the air, aluminum is easy to oxidize and combine, forming a dense aluminum oxide film with a thickness of approximately 0.1-0.2 μ m) The melting point is high (about 2050 ℃), far exceeding the melting point of aluminum and its alloys (about 600 ℃). The density of aluminum oxide is 3.95-4.10g/cm3, which is about 1.4 times that of aluminum. The surface of the aluminum oxide film is prone to adsorbing water, which hinders the fusion of the base metal during welding and can easily form defects such as pores, slag inclusions, and lack of fusion, leading to a decrease in weld performance.
