Ballistic Steel Vs Aluminum: Comparing Properties of Bullet Resistant Alloys

Ballistic steel and aluminum are two principal alloys widely adopted in modern protective systems, valued for their ability to resist high-velocity impacts and maintain structural integrity under ballistic stress. Whether integrated into architectural fortifications, transport vehicles, or security infrastructure, these materials are engineered to perform when subjected to intense pressure. Although both are designed to withstand the force of projectiles without structural failure, their properties differ significantly.

Hardness and Strength

The exceptional hardness of ballistic steel, typically around 500 Brinell, equips it to resist direct projectile penetration with ease. Moreover, its tensile strength often surpasses 1,100 megapascals, adding to its overall ballistic performance. Ballistic aluminum, including armor-grade alloys like 5083, 7039, and 2519, usually deliver tensile strengths between 250-500 megapascals. Whereas steel’s superior hardness makes it better at withstanding sharp, high-energy impacts, aluminum achieves a notable level of strength through its efficient balance of force and weight.

Density and Weight

With a density close to 7.8 grams per cubic centimeter, ballistic steel adds significant mass to any protective structure. Unfortunately, its weight can become a drawback in scenarios where speed, mobility, or ease of installation is important. In contrast, ballistic aluminum, weighing in at just 2.7 grams per cubic centimeter, dramatically reduces the load on supporting structures. This weight difference means aluminum is often favored in applications requiring agility and transportability, such as military vehicles, aircraft, or mobile security units. Alternatively, steel is preferred for stationary installations like ballistic doors, safe room walls, or fixed perimeter barriers requiring maximum impact resistance.

Ballistic Resistance Mechanisms

Ballistic steel offers protection through its mass and hardness, using such characteristics to stop or deflect incoming projectiles through sheer physical strength. By increasing the thickness of ballistic steel its defensive capability can be enhanced, ensuring its suitability for fixed installations where weight is less of a constraint. Conversely ballistic aluminum absorbs impact energy with mechanisms like internal deformation and shear banding.

Failure Modes and Energy Absorption

When subjected to high-impact stress, ballistic steel may fracture or spall, producing dangerous shards that pose risks to occupants. This brittleness is a challenge in enclosed or inhabited environments. However, despite its potential for spalling, ballistic steel remains highly effective for structural applications that require maximum hardness, rigidity, and multi-hit durability like fortified entryways and fixed ballistic barriers. Ballistic aluminum tends to fail in a more controlled manner, deforming plastically to absorb and distribute impact energy. Its ability to limit fragmentation and reduce the likelihood of ricochet or internal debris means ballistic aluminum provides clear advantages for confined or personnel-heavy settings.

Corrosion Resistance and Durability

The long-term durability of ballistic steel often depends on the use of protective coatings, as it is more prone to corrosion in its untreated form. With the right surface treatments though, ballistic steel performs reliably even in demanding environments. Ballistic aluminum, in contrast, benefits from natural corrosion resistance due to its oxide layer, which reduces the need for additional coatings. Possessing such a property enhances aluminum's long-term durability in harsh or low-maintenance settings, like coastal, humid, or remote locations, where routine upkeep may be difficult. Steel, on the other hand, performs best in controlled environments where corrosion protection can be constantly maintained.

Manufacturability and Design Flexibility

Although the hardness of ballistic steel offers robust protection, it can make fabrication more demanding. Processes like cutting, welding, and forming often require specialized tools and longer production timelines. Ballistic aluminum is much easier to machine and shape, allowing for greater flexibility in a wider range of design applications, like modular wall systems and custom architectural facades. Overall, ballistic aluminum is useful for structures that benefit from lightweight, modular, or curved components. Ballistic steel remains the best option for high-strength builds that need maximum rigidity.

Which Material Should Be Used?

The final choice between ballistic steel or aluminum depends on the specific demands of their intended application. Ballistic steel provides formidable hardness and structural integrity, which is ideal for fixed installations in high-risk environments, and ballistic aluminum offers a more agile, corrosion-resistant, and fabrication-friendly solution that maintains protective integrity while enabling lighter builds. These bullet-resistant alloys each have their own distinct properties that enable their effectiveness in meeting performance, weight, and fabrication requirements.

If you are unsure about whether to select ballistic steel or aluminum, Action Bullet Resistant can help. We incorporate both materials into our engineered systems, ensuring every product is tailored to meet certain performance specifications, environmental conditions, and design goals. Contact us today and let us help you pick the right material.

FAQ:

1) What is ballistic steel?

Ballistic steel is a high-hardness alloy engineered to resist projectile penetration and deformation. With a typical hardness of around 500 Brinell and tensile strength exceeding 1,100 MPa, it’s ideal for fixed installations requiring maximum impact resistance.

2) What is ballistic aluminum?

Ballistic aluminum is an armor-grade lightweight alloy (often 5083, 7039, 2519) designed to absorb and dissipate impact energy. It provides strong ballistic performance with only one-third the weight of steel, making it popular in mobile or modular applications.

3) Which material is stronger against penetration?

Steel generally provides greater resistance to penetration because of its density and hardness, making it suitable for doors, walls, and vaults. Aluminum performs well against small-arms threats but typically requires thicker panels to achieve similar ratings.

4) Which is lighter?

Aluminum is much lighter, with a density of about 2.7 g/cm³ compared to steel’s 7.8 g/cm³. This makes aluminum better suited for vehicles, aircraft, or retrofit systems where weight reduction is crucial.

5) Which absorbs impact energy better?

Steel resists and deflects rounds through hardness, while aluminum absorbs and disperses energy plastically, reducing ricochet and spall. Aluminum is often preferred in inhabited or personnel-dense areas.

6) How do they differ in corrosion resistance?

Steel requires coatings or finishes to prevent corrosion; aluminum naturally forms an oxide layer that protects it, making it ideal for coastal or humid environments.

7) Which material is easier to fabricate?

Aluminum is easier to machine, cut, and shape, allowing more complex designs such as curved or modular panels. Steel, while harder to fabricate, offers superior rigidity and minimal flex once installed.

8) Which should I choose for my project?

Choose ballistic steel for permanent, high-risk, or maximum-strength structures. Choose ballistic aluminium for lightweight, modular, or corrosion-prone environments. Action Bullet Resistant engineers both materials into fully certified systems tailored to each project’s needs.