Aluminum Sheet Alloys
October 27, 2025Comments
Steel grades—excluding stainless steels—typically are named after their mechanical performance and production route (cold- or hot-rolled). Names may be based on their deep drawability (CR3, DX54), yield strength (CR210LA, S700MC), tensile strength (SPC340BH, HDT590X) or both (CR330Y590T-DP)
Aluminum alloys are different. First, automotive OEMs only recently started standardizing their aluminum alloys. The distinction between hot- and cold-rolled usually is not critical. Instead, most alloy nomenclature relates to composition. In North America, the Aluminum Association defines a four-digit code for each alloy (Table 1). These digits often follow the letters AA. Example: alloy AA6016, which may be referred to as EN-AW6016 in Europe, where EN stands for European Norm and AW stands for wrought aluminum.
Cracking the Code: What Do the Four Digits Mean?
The first of the four digits in the alloy designation indicates the main alloying element, and also provides information about the tempers. In 1xxx-series grades, the last two digits indicate the aluminum percentage. AA1050, then, contains 99.50% Al, while AA1098 contains 99.98% Al. The last two digits do not have any significant meaning in other alloy series (2xxx to 8xxx). AA2014 is the 14th registered alloy in copper-alloyed grades, and AA6014 is the 14th alloy in Mg-Si-alloyed grades.
The second digit in the alloy designation also tells a story. A zero indicates an original alloy, while any other number indicates some modification of the original alloy. Example: AA5054 is the original 54th alloy in Mg-alloyed aluminum grades, and AA5754 is the 7th modification of the same alloy.
The four digits may be followed by a letter, which indicates the variation of the alloy. AA6110A, for example, is a variation of AA6110, which itself is a modification of AA6010. Table 2 provides the chemical compositions of these grades, as defined by the Aluminum Association.
How About Mechanical Properties?
An aluminum alloy’s name does not indicate its strength (yield or tensile), unless the name also includes the temper—indicated by a letter and often followed by one or more numbers. Temper designation provides the processing history and defines the strength-ductility level of the material (Table 3).
It also is critical to note that only 2xxx, 6xxx and 7xxx-series alloys, as well as some 4xxx grades, can be heat treated.
The answer to this question depends on the definition of “easy.” When working with soft tempers of 5xxx or 6xxx aluminum grades, yield and tensile strength are similar to or perhaps less than that of mild steels—it will take less load to bend the aluminum. However, the aluminum sheet will exhibit much more springback than a steel sheet at a similar strength level, as aluminum has one-third the elastic modulus. Looking at the curves in Fig. 1, it is clear that press-forming aluminum requires less force and energy compared to steel (with the specific grades shown in the figure). 
It is assumed—and mostly true—that an alloy with a higher total elongation also has more formability. Thus, one easily can check the graphs in Fig. 2 and say that aluminum is less formable than steel. Now imagine a steel grade with a total elongation similar to that of aluminum. The next property to consider: m-value. When local necking starts, strain rate in the necked area becomes much higher than in its surrounding non-necking area. With a negative strain-rate sensitivity, the necked area would be softer than the surrounding area. As both the strength and cross-sectional area get smaller, we should see fracture very soon after necking initiation. Table 4 illustrates how close together the values are for uniform and total elongation of aluminum alloys.
Another formability measure is plastic anisotropy (resistance to thinning), or r-value, often referred to as the Lankford coefficient. Aluminum alloys may have r values as low as 0.3, depending on the rolling direction, alloy and temper. The grades investigated here have r-values less than 1, indicating that they will thin more quickly than their width reduction. A draw-quality steel, on the other hand, has an 
