6061 aluminum square tube is mainly composed of aluminum, magnesium, silicon three elements, but also contains a small amount of copper, manganese, chromium, zinc, titanium and other elements. The mass fraction of each element is roughly 0.4%-0.8% silicon, 0.7% iron, 0.15%-0.4% copper, 0.15% manganese, 0.8%-1.2% magnesium, 0.04%-0.35% chromium, 0.25% zinc, 0.15% titanium, and the rest is aluminum.