2. Aluminum alloy is the most widely used non-ferrous metal structural material in industry, which has been widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding, chemical industry and other industries. With the rapid development of industrial economy, the demand for aluminum alloy welded structural parts is increasing, which makes the research on aluminum alloy weldability deepen.
3. Aluminum alloys usually use alloying elements, such as copper, zinc, manganese, silicon and magnesium. It was invented by Alfred Wilm, a German at the beginning of the 20th century, which is of great help to the development of aircraft. After World War I, the composition of aluminum alloy was listed as a state secret in Germany. Compared with ordinary carbon steel, it is lighter and corrosion resistant, but its corrosion resistance is not as good as that of pure aluminum. In a clean and dry environment, a protective oxide layer will be formed on the surface of aluminum alloy.