Table of Contents
What is 2024 Aluminum?
2024 Aluminum is created by adding small amounts of metallic elements into a base metal to improve its characteristics. These “alloying” elements allow a base metal to be more useful in different circumstances, and the alloying process has been widely used to enhance aluminum in that same way. Aluminum alloys are a class of engineering materials on their own, where each alloy has attributes such as high strength, conductivity, and even resistance to environmental effects. There are so many types of aluminum alloys that a naming system was developed by the Aluminum Association, America’s chief authority on aluminum and its derivatives, to organize them. This naming system separates aluminum alloys using four-digit designators (1xxx, 2xxx, 3xxx, etc.), where the first digit represents the specific alloying elements and general characteristics of the group, or the “series” (feel free to read our article all about 6061 aluminum alloy for an explanation of the last three digits). The focus of this article, 2024 aluminum, hails from the 2xxx series of aluminum alloys or those which contain copper as their main alloying element. 2024 aluminum is widely used for its high strength, and this article will highlight the properties that allow it to excel in such applications.
Physical Properties of 2024 Aluminum
Each alloy contains a specific percentage of alloying elements that imbue the base aluminum with certain beneficial qualities. In 2024 aluminum alloy, these elemental percentages are 4.4% Cu, 1.5% Mg, and 0.6% Mn, nominally. This breakdown explains why 2024 aluminum is known for its high strength because copper, magnesium, and manganese greatly increase the strength of aluminum alloys. This strength comes at a disadvantage, however; the high percentage of copper in 2024 aluminum greatly reduces its resistance to corrosion. There are usually trace amounts of impurity elements (silicon, iron, zinc, titanium, etc.), but these are only purposefully given tolerances as-per the buyer’s request. Its density is 2.77g/cm3 (0.100 lb/in3), which is slightly higher than pure aluminum (2.7g/cm3, 0.098 lb/in3). 2024 aluminum is machined very easily and has decent workability, allowing it to be both cut and extruded if need be.
Corrosion Resistance & Cladding
As previously mentioned, bare 2024 aluminum alloy is more prone to corrosion than most other aluminum alloys. Manufacturers have addressed this issue by coating these susceptible alloys with a layer of corrosion-resistant metal (referred to as “galvanizing” or “cladding”). This coat is sometimes high purity aluminum or even another alloy, and is most popular in clad sheet metal where the original alloy can be sandwiched between the cladding layers. Clad aluminum is so popular that a series of AlClad products have been developed and are widely used to give corrosion-weak alloys like 2024 the best of both worlds. This development makes 2024 aluminum especially useful because its strength can be implemented where the bare alloy would normally degrade.
Heat-Treatment for Increased Strength
Some aluminum alloys such as the 2xxx, 6xxx, and 7xxx series can be strengthened using a process known as heat-treatment. This process involves heating the alloy to a specific temperature to allow the alloying elements to mix, or “homogenize” into the base metal, and then quenching it in a solution to lock these elements in place. This step is known as “solution heat treating.” These elements are unstable, and when the piece cools, they will precipitate out of the aluminum “solution” as compounds (for example, copper atoms will precipitate out as Al2Cu). These compounds increase the overall strength of the alloy via interactions with the aluminum’s microstructure, and this process is known as “aging.” The processes of solution heat-treating and aging are important to know, because there are many types of 2024 aluminum based on how these steps are carried out and are given such designators as 2024-T4, 2024-T59, 2024-T6, etc.
Type 2024 aluminum gains its optimal strength qualities not just from composition alone, but from the procedure by which is it heat-treated. There are many different procedures, or “tempers” of aluminum (given the designator -Tx, where x is a one-to-five digit long number), which all have their unique properties despite being the same alloy. The first digit following the “T” indicates the basic heat treatment method and optional second-to-fifth digits indicate specific manufacturing qualities. For example, in the 2024-T42 temper, the “4” indicates that the alloy is strengthened with solution heat-treating and natural aging, but the “2” indicates that the buyer must heat-treat the metal themselves. This system can get confusingly specific, so for the duration of this article, we will display the strength values for only one of the more basic tempers, 2024-T4 aluminum.
Mechanical Properties
There are certain mechanical properties that can be used to specify an aluminum alloy. For an alloy such as 2024 aluminum, some important measures are ultimate strength, yield strength, shear strength, fatigue strength, as well as the modulus of elasticity and shear modulus. These values will give an idea as to the workability, strength, and potential uses of a material, and are summarized below in Table 1.
The yield and ultimate strengths are the maximum amount of stress that will non-permanently and permanently deform a specimen of alloy, respectively. For a more in-depth discussion of these values, feel free to visit our article on 7075 aluminum alloy. They are important when using an alloy in static applications where permanent deformation should not occur, like in buildings or safety equipment. 2024 aluminum has impressively large ultimate and yield strengths at 469MPa (68,000 psi) and 324 MPa (47,000 psi), which makes it attractive for high-strength structural materials such as aluminum tubing.
Shear and fatigue strength are measures of a material’s resistance to specific stressors. For shear strength, this means the resistance to shearing stresses, also known as “cutting” stresses (our article on 6061 aluminum provides an intuitive explanation of these forces). The shear strength of 2024 aluminum is 283 MPa (41,000 psi), which is moderately strong while still allowing it to be cut from common bar stock. Fatigue strength, on the other hand, is a valuable measure for alloys that appear in aerospace applications such as 2024 aluminum. Aircraft experience periodic stresses (such as from takeoff, landing, etc.), which may not deform the alloy initially; however, when repeatedly exposed to these smaller stresses, the alloy may weaken microscopically and then eventually macroscopically, given enough time. The fatigue strength is the measure of how resistant a material is to breaking under such fatigue, and the fatigue strength for 2024 aluminum is 138 MPa (20,000 psi), calculated with 500,000,000 cycles of loading under the yield point.
Finally, the modulus of elasticity and shear modulus are parameters that display how “resilient” a given material is to deform. They give a good idea as to a material’s resistance to permanent deformation. For 2024 aluminum alloy, the modulus of elasticity is 73.1 GPa (10,600 ksi), and the shear modulus is 28 GPa (4,060 ksi), which is even greater than that of other high strength aircraft alloys such as 7075 aluminum.
Summary of mechanical properties for 2024 aluminum alloy.
| Mechanical Properties | Metric | English |
| Ultimate Tensile Strength | 469 MPa | 68000 psi |
| Tensile Yield Strength | 324 MPa | 47000 psi |
| Shear Strength | 283 MPa | 41000 psi |
| Fatigue Strength | 138 MPa | 20000 psi |
| Modulus of Elasticity | 73.1 GPa | 10600 ksi |
| Shear Modulus | 28 GPa | 4060 ksi |
Applications of 2024 Aluminum
Type 2024 aluminum has excellent machinability, good workability, high strength, and can be made to resist corrosion with cladding, making it an optimal choice for aircraft and vehicle applications. 2024 aluminum is used throughout many industries, but some common applications for this excellent alloy are as follows:
Truck wheels
Structural aircraft parts
Gears
Cylinders
Pistons
Summary
This article presented a brief summary of the properties, strength, and applications of 2024 aluminum.
XTJ is a leading OEM Manufacturer that is dedicated to providing one-stop manufacturing solutions from prototype to production. We are proud to be an ISO 9001 certified system quality management company and we are determined to create value in every customer relationship. We do that through collaboration, innovation, process improvements, and exceptional workmanship.
