Due to its strength properties, pure 4mm aluminum sheet is rarely chosen for structural fabrication. Although the 1xxx series are nearly pure aluminum, they can be susceptible to strain hardening, especially if they contain significant amounts of impurities such as iron and silicon. However, even in the strain hardening condition, the strength of the 1xxx aluminum alloys is low compared to other series of aluminum alloys.
When 1xxx series alloys are selected for structural applications, it is usually because of their excellent corrosion resistance and/or high electrical conductivity. The most common applications for the 1xxx series alloys are aluminum foil, electrical bus bars, metallized welding wire, chemical tanks and piping systems.
Adding alloying elements to aluminum is the main method used to produce a variety of different materials that can be used in a wide variety of structural applications.
If we consider the seven specified aluminum alloy families for wrought alloys, we can immediately identify the main alloying elements used to produce each alloy family. We can then further study the effect of each of these elements on aluminum.
The main effects of alloying elements in aluminum alloy sheets are as follows:
2XXX aluminum alloy: Aluminum-copper alloys typically contain 2% to 10% copper with minor additions of other elements. Copper greatly increases strength and promotes precipitation hardening. Adding copper to aluminum also reduces ductility and corrosion resistance.
The susceptibility to solidification cracking of aluminum-copper alloys increases. Therefore, some of these alloys may be the most challenging aluminum alloys to weld. These alloys include some of the highest heat-treatable aluminum alloys. The most common applications for 2xxx series alloys are aerospace, military vehicles and rocket wings.
3xxx aluminum alloy: Manganese is added to aluminum to increase its strength through solid solution strengthening. It also improves strain hardening without significantly reducing ductility or corrosion resistance. These are medium-strength, non-heat-treatable materials that retain strength at elevated temperatures and are rarely used in primary structural applications. The most common applications for the 3xxx series alloys are kitchen appliances, radiators, air conditioning condensers, evaporators, heat exchangers and associated piping systems.
5xxx aluminum alloy: The addition of magnesium to aluminum increases its strength through solid solution strengthening and increases its ability to strain harden. These alloys are the strongest non-heat-treatable aluminum alloys and are therefore widely used in structural applications. The 5xxx series alloys are produced primarily as aluminum sheet like 6mm aluminum sheet. Some common applications for 5xxx aluminum alloys include truck and train bodies, buildings, armored vehicles, ships, chemical tankers, pressure vessels, and cryogenic storage tanks.
6xxx aluminum alloy: The addition of magnesium and silicon to aluminum produces complex magnesium silicides (Mg2Si). The formation of this compound makes the 6xxx series heat resistant. The 6xxx series alloys are easy and cost-effective to extrude. For this reason, 6xxx alloys are most commonly found in a wide variety of extruded shapes. These alloys form important complementary systems with the 5xxx series alloys. Some common applications for 6xxx series alloys are armrests, drive shafts, automotive frame sections, bicycle racks, tubular lawn furniture,etc.