Structural aluminum is an extruded aluminum alloy that goes through post-forming treatments to become lightweight, 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, in which aluminum, manganese, and silicone are the major elements.
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Applications of Structural Aluminum
Structural aluminum is commonly used in the marine, automotive, engineering, and construction industries to produce machine bases, building structural framing, cryogenic vessels, piping, bridges, and industrial machinery. In addition, structural aluminum can be formed into many different shapes, including castings, forgings, wire, rod, bar and flat rolled sheets (thinner than .25 inches) or plates (thicker than .25 inches).
Manufacturing Process of Structural Aluminum
Extruded aluminum is stronger and more durable than other kinds of aluminum because of the way in which it has been machined. The extrusion process entails forcing round aluminum stock called "billets" by means of a ram through a die. A die is a hollow profile that shapes the aluminum into a specific extruded shape as the billet is squeezed through.
In addition to the extrusion process, structural aluminum is also put through cold working and heat treatments after forming to increase these properties. Aluminum may be cold rolled, drawn, straightened, or flattened, all of which are done at or around room temperature. When cold-worked, a negative is that aluminum will often lose some of its ductility in the process.
All of these processes change the internal grain characteristics and increase tensile strength, yield strength, and hardness. To obtain the desired strength, structural aluminum is heated at a high temperature for a certain amount of time, then quickly cooled by quenching (i.e., immersing the metal in cool water). Age hardening also increases aluminum's properties. In this process, the metal is slowly heated and kept at that temperature for a long period of time, strengthening the aluminum's grain.
Benefits of Using Structural Aluminum
Although structural aluminum is more costly than other metals, it has a much quicker manufacturing process and low cost of labor. Benefits of structural aluminum include its cleanliness, as well as the fact that it is an aesthetically-pleasing material without the addition of painting or other methods of further finishing.