Below is a list of Structural Aluminum manufacturers from Chicago, Illinois. Structural aluminum is an extruded aluminum alloy that goes through post-forming treatments in order to become light weight, durable and corrosion resistant metal used in many different high-strength applications. Because pure aluminum is too soft to be used in structural applications, it is alloyed with magnesium, silicon, zinc, copper, zirconium, chromium and manganese. The most common aluminum alloy used as structural aluminum is 6061-T6, which is an alloy in which aluminum, manganese and silicone are the major elements.