Aluminum is almost never just aluminum. While it is possible to buy pure and high-purity aluminum, they are almost never used as-is. This nearly pure aluminum is used as a feedstock for deposition chambers to coat other structural materials with a thin layer of aluminum, or as a chemical, thermal, or electrical control material in testing. Aluminum is almost never used in its pure state, and it is certainly never used as a structural material.

The aluminum that most people encounter in daily life are in fact aluminum alloys—carefully blended with other metals and materials like silicon, and heat treated to create desirable properties. The following are the properties of these aluminum alloys:

• greater strength
• enhanced corrosion resistance
• increased electrical and thermal conductivity

While these alloys share commonalities, such as in terms of thermal conductivity, each heat treatable alloy has its own unique physical properties.

Common Aluminum Alloy Properties

Aluminum is famously a lightweight material. This property has made certain aluminum alloys a go-to choice for aircraft, spacecraft, and ground vehicles where weight savings result in significant improvements in performance. This isn’t wrong, but it would be more accurate to say that one of the most valuable aluminum alloy properties is its high strength-to-weight ratio. This is a near-universal advantage of aluminum alloys, some other advantages are:

• Conductivity: Aluminum conducts both heat and electricity very well. It is second only to copper in this ability, and this has made it desirable for heat sinks, radiators, and electrical wiring.
• Cold Stable: Many metals become brittle as temperatures drop. Aluminum is not one of these metals. Aluminum in fact grows stronger while remaining flexible. This makes it useful for a range of cryogenic applications.
• Corrosion Resistance: Aluminum, when exposed to air, develops a thin layer of oxide that protects the surface and increases its corrosion resistance. This makes structural aluminum very long-lasting with low maintenance needs compared to metals like steel.
• Non-magnetic: In spite of its electrical conductivity, aluminum is non-magnetic. This makes it useful for busbars and other high electrical load components where magnetic interactions would be an issue. It also makes excellent housing and casings for magnetic materials like compasses and hard drives.
• Non-sparking: Aluminum is non-sparking against itself and ferrous metals. This property is useful in environments where flammable fumes or combustibles are a potential hazard.

These aluminum alloy properties will hold true no matter what the formulation of any particular aluminum alloy is. The main difference in aluminum alloy properties between alloys is their mechanical properties, or how they act under tension and strain. Another potential concern is their workability—whether or not an aluminum alloy can undergo the machining or welding process easily without compromising its mechanical or structural properties.

Mechanical and Structural Aluminum Alloy Properties

An aluminum alloy can take on a range of different properties depending on the other elements added to the alloy alongside the aluminum. Common elements include metals like magnesium, copper, and zinc. They can also include nonmetallic elements like silicon. These additional elements can add strength, or they can also add characteristics to the aluminum when it is worked. The addition of silicon and zinc can make aluminum flow better when it is molten—allowing for better casting at the cost of interfering with the anodizing response and making anodizing cast aluminum a challenge.

In addition to these alloying elements, there are also different treatments that substantially affect the strength of the alloy. Artificially aged T6 aluminum is effectively heat treated for extra strength, while T4 aluminum is naturally aged or allowed to sit until it becomes stabilized and stronger. Then there are hardening treatments where the aluminum is deliberately strained beyond its yield point making it more difficult to deform in the future. Afterward, they may then be annealed, or heated and allowed to naturally cool to further enhance their strength.

The Most Important Aluminum Alloy Property: Strength

When it comes to aluminum alloy properties, strength is probably of the most immediate concern. It’s the property that will most often make the difference between success and critical failure of anything built with aluminum.

Strength can have a variety of definitions but the most common is material tensile strength—strength when being pulled or bent. Other definitions include:

• Yield Strength: the force where it finally gives way
• Elastic Modulus: the force it can resist before deforming 
• Shear Modulus: the parallel force it can resist before deforming

A chart of aluminum alloy properties for these different definitions of the most common aluminum alloys can be seen below.

Aluminum Alloy Properties
Alloy	Temper	Elastic Modulus	Shear Modulus	Yield Strength	Tensile Strength
1100	–	10, 000,000 psi	3,750,000 psi	3,500 psi	11,000 psi
1100	H12	10, 000,000 psi	3,750,000 psi	11,000 psi	14,000 psi
2014	–	10, 800,000 psi	4,000,000 psi	8,000 psi	22,000 psi
2014	T6	10, 600,000 psi	4,000,000 psi	58,000 psi	66,000 psi
2014	T62	10, 800,000 psi	4,000,000 psi	59,000 psi	67,000 psi
2017	T4	10, 500,000 psi	3,950,000 psi	32,000 psi	55,000 psi
2024	T3	10, 600,000 psi	4,000,000 psi	42,000 psi	64,000 psi
2024	T4	10, 600,000 psi	4,000,000 psi	40,000 psi	62,000 psi
2025	T6	10, 400,000 psi	3,900,000 psi	33,000 psi	52,000 psi
2124	T851	10, 400,000 psi	4,000,000 psi	57,000 psi	66,000 psi
2219	T62	10, 500,000 psi	4,000,000 psi	33,000 psi	54,000 psi
2618	T61	10, 700,000 psi	4,100,000 psi	42,000 psi	55,000 psi
3003	–	10, 000,000 psi	3,750,000 psi	5,000 psi	14,000 psi
3003	H18	10, 000,000 psi	3,750,000 psi	25,000 psi	27,000 psi
3003	H112	10, 000,000 psi	3,750,000 psi	10,000 psi	17,000 psi
354	T61	10, 600,000 psi	4,000,000 psi	36,000 psi	47,000 psi
355	T51	10, 200,000 psi	3,800,000 psi	22,000 psi	27,000 psi
355	T6	10, 300,000 psi	3,800,000 psi	23,000 psi	37,000 psi
356	T7	10, 300,000 psi	3,850,000 psi	21,000 psi	29,000 psi
356	T6	10, 300,000 psi	3,850,000 psi	20,000 psi	30,000 psi
5052	–	10, 200,000 psi	3,800,000 psi	9,500 psi	25,000 psi
5052	H32	10, 200,000 psi	3,800,000 psi	23,000 psi	31,000 psi
5056	H38	10, 300,000 psi	3,750,000 psi	50,000 psi	60,000 psi
5056	ANL	10, 300,000 psi	4,000,000 psi	22,000 psi	42,000 psi
6061	T4	10, 000,000 psi	3,800,000 psi	16,000 psi	30,000 psi
6061	T6	10, 000,000 psi	3,800,000 psi	35,000 psi	42,000 psi
6062	–	10, 000,000 psi	3,750,000 psi	5,000 psi	14,000 psi
6062	T4	10, 000,000 psi	3,750,000 psi	16,000 psi	26,000 psi
6062	T6	10, 000,000 psi	3,750,000 psi	35,000 psi	38,000 psi
6063	T42	10, 000,000 psi	3,750,000 psi	10,000 psi	17,000 psi
6063	T5	10, 000,000 psi	3,750,000 psi	16,000 psi	22,000 psi
6063	T6	10, 000,000 psi	3,750,000 psi	25,000 psi	30,000 psi
6151	T6	10,100,000 psi	3,850,000 psi	37,000 psi	44,000 psi
7050	T7452	10,100,000 psi-11,600,000	–	60,000 psi	68,000 psi
7050	T74	–	–	58,000 psi	70,000 psi
7075	T6	10, 400,000 psi	3,900,000 psi	70,000 psi	78,000 psi
7075	T6	–	–	63,000 psi	73,000 psi
A356	T651	10, 400,000 psi	3,900,000 psi	28,000 psi	38,000 psi
D712	T5	10, 300,000 psi	3,800,000 psi	20,000 psi	32,000 psi

These are only the most common aluminum alloys, there are others in widespread use, including proprietary aluminum alloys like Mic 6 and alternatives like Alimex and Alca 5. The most important aluminum alloy properties in those cases aren’t necessarily their overall strength. Instead, it is their dimensional stability while being machined, closely followed by their ability to remain dimensionally stable under changing temperatures.

Other proprietary blends like Duramold and Aluminum Max 5 by PCP are made specifically for use in vacuum and injection-forming molds. If there is an industrial use for aluminum alloys then there is a formulation and treated alloy with aluminum alloy properties that are specially made with that use in mind.

It can be difficult to know what the most important aluminum alloy properties actually are, even if you are an expert metalworker or machinist.

A Supplier Who Can Find the Aluminum Alloy With Properties You Need

If your head is spinning trying to figure out what aluminum alloy and properties you need, then turn to an expert. Industrial Metal Service has been a leading aluminum provider for silicon valley businesses for decades. We are now bringing our expertise in aluminum and metals nationwide.