Aluminum may not be the first metal a person thinks of when someone mentions armor plating, but with the recent advances in high performance aluminum alloys, more and more manufacturers are turning to aluminum for their armor plating needs. Aluminum has several characteristics that make it a perfect choice for armor plating, and the latest alloys are able to outperform alternative materials.
Anyone who works in an industry that relies on armor plating should already be familiar with aluminum and its many alloys, as well as the processes used in its manufacturing. Armor plating must be made with only the most reliable materials, and customers depend upon its durability and protection. One of the best ways to ensure that your aluminum products are of the highest quality is by partnering with a material supplier who is experienced in providing its customers with unparalleled service throughout their entire procurement process.
What is armor plating?
Armor plating is commonly used to protect military vehicles from impacts caused by bullets, missiles, explosives and shrapnel. Such vehicles can be designed for use on the land, air or sea and include tanks, troop carriers, and the like. Civilian vehicles can also be reinforced with armor plating, such as government vehicles, armored cars used for the transport of money and other valuables, and security vehicles for high-risk individuals. Even some spacecraft are reinforced with armor plating.
The type of plating depends largely on the mobility needs of the vehicle. A slow moving tank will likely be fitted with heavier and thicker materials than a small, fast vehicle designed to transport personnel in a conflict zone, for example.
By the same token, armor can be made from a wide variety of materials, including aluminum, stainless steel, wrought iron, titanium, Kevlar, high performance ceramics, buckypaper and aluminum foam. Today, there is an increasing use of nano materials and composites that would have been undreamed of a few decades ago.
What makes aluminum a good choice for aluminum plating?
There are several benefits that make aluminum an excellent material in many kinds of armor plating. First, the most obvious attribute that is appealing about aluminum is its light weight. Aluminum has a density that is about one third that of steel, making it one of the lightest metals. Yet it still offers a high strength-to-weight ratio. Ballistic performance must be balanced with light weight for vehicles that need to be transported by air, such as troop carriers.
Pure aluminum is soft and lacks the strength necessary for most high performance applications, so it was only with the development of aluminum alloys, with added magnesium, copper, silicon, zinc and other elements, that the high strength aluminum products commonly used today became available.
In addition to its high strength-to-weight ratio, another benefit of aluminum that makes it ideal for armor plating is its corrosion resistance. Aluminum naturally forms a passivation layer, as its surface reacts to the oxygen in the air around it. Certain alloys are so resistant to corrosion they can be used in marine applications or other environments that are highly volatile.
It should be noted that aluminum, while widely used in armor plating for vehicles, is not frequently found in body armor or helmets. This is because certain high-grade ceramics are more popular, although one material in wide use for these ceramics is alumina, which is a commonly found ore containing aluminum.
Which alloys are best suited for aluminum plating?
The primary considerations used in selecting alloys for aluminum plate are ballistic protection, weldability and corrosion resistance. Ballistic protection is measured with a couple of different metrics: the ability to resist penetration by an armor piercing (AP) projectile with a pointed leading end such as a .30 caliber; and the ability to resist spallation by a fragment stimulating (FS) projectile with a blunt leading end such as a 20 mm. Spallation is the fragmentation of the back side of an armored plate opposite the point of projectile impact caused by a compressive wave.
The most widely accepted aluminum alloys for armored plate applications are 5083, 6061 and 7039. 5083 meets the requirements of U.S. Military Specification MIL-A46027F while 7039 meets U.S. Military Specification MIL-A46063E. While 7039 is more effective in AP performance, 5083 fares better in FS applications. The improved ballistic characteristics of 7039 are offset by its lower corrosion resistance and difficulty in welding.
A balance must be struck between the 5xxx, 6xxx and 7xxx series of alloys according to the armor application and the characteristics of the grades’ performance. New alloys are always under consideration that improve the weldability, corrosion resistance and ballistic performance of approved grades. 5059 shows improved blast protection to 5083 and has been outfitted in the military’s new RG-33 Mine Resistant Ambush Protected (MRAP) vehicles while 7017 has shown a reduction in spallation as compared to the 7039 standard.
Any new aluminum alloys for prospective armor plate applications are tested at the Army Research Laboratory at the Aberdeen Proving Grounds in Maryland. After being granted approval, every production lot requires a coupon sample to be submitted to a ballistics laboratory such as that at Aberdeen, who then puts the sample through an actual projectile firing test to prove out the material.
Many of the most used alloys in armor plating come from the 5xxx series. These non-heat treatable alloys use magnesium as the primary alloying agent and are recognized for having the highest strength of the alloys that can’t be heat-treated. These alloys are also well suited for welding, which is why in addition to armor, these alloys will also be frequently found in shipbuilding, transportation, architecture and similar applications. Specific 5xxx alloys used for armor plating include 5456, 5083 and 5059.
The 6xxx series of alloys are frequently used directly as plate in applique armor systems, such as the “up-armoring” programs that were employed to improve the protection of the military’s High-Mobility Multipurpose Wheeled Vehicle (HMMWV or Humvee) against improvised explosive devices. 6061 is the most frequently used grade from this family in applique systems.
The 7xxx family of alloys is commonly found in aerospace applications, where weight, strength, and durability are all critical considerations, so it’s no surprise that these alloys can also be found in armor plating. These heat treatable alloys use zinc as the primary alloying element. Not all the alloys in this category are easily weldable. The specific alloys found in armor plating include 7017, 7029, 7039, 7056, 7075 and 7085.
What industries are likely to use aluminum plating?
Any industry that relies on armor plating will likely employ aluminum alloys in many of their vehicles. Obviously, the military is the most prominent example, and the earliest known uses of aluminum being used in military vehicles date back to the 1890s, when French torpedo boats were made of aluminum.
Other industries that rely on armor plating include security transports, such as limousines and luxury sedans, armored transports, especially for banks and jewel companies, and sport vehicles. With continued advances in high-performance aluminum alloys, the future will almost certainly hold even more examples.
Your Technical Services Professional
With its high strength, low weight, and excellent corrosion resistance, aluminum is a highly valued material for military applications, including armor plating. To ensure the success of any armor plate products and solutions, it’s important to partner with a seasoned material supplier. At Clinton Aluminum a team of sales professionals is committed to working with customers through every step of their procurement process. Contact a friendly and knowledgeable service representative today.