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Special Steel for Vehicle Armoring In Todays Army

Vehicle armoring is commonly used in the military to enable vehicles to withstand the impact from shells, bullets, or missiles to protect the army members from being attacked by their enemies (Hadjioannou, Michalis, and Matt Barsotti np). Special steel has to be used to armor army ships, aircraft, fighting vehicles, and tanks. There are various varieties of steels that can be used for vehicle armoring, but the commonly used are martensitic- hardened steel. The active compounds of these hardened steels are carbon and iron. There are specific chemical standards for military-level steel, like the maximum carbon Weight that is needed is normally 0.32%. The standards set for the steel focuses on two primary aspects that are, ballistic limit and hardness. In this report, the Rolled homogenous armor steel plate’s properties and how it has been used in today’s army vehicles will be discussed.

History

The history of the amour steel plate is traced way back to the year 1485 when Leonardo da Vinci explained his idea of an armored car, and it has offered optimal ballistic performance in a range of battlefields. Leonardo da Vinci is the forefather of the modern tank. He was the one who invented the first armored car that could move in all directions and was fully equipped with weapons. The most popular intention of da Vinci was the armored war car that he used to help him to scatter and intimidate his rival army (Evans, William, et al. pg1). Since its invention, the thickness required for this ballistic steel has increased in time significantly.

The United States army introduced the homogenous steal over 80 years back when they developed the first tank. The tanks were constructed to have low carbon and had a composition of special medium alloy steels. During the world war, the rolled homogenous armor underwent vital variations in alloy conservation properties, resulting in an armor that had low-alloy material and low carbon consistent. In world war two, a thicker steel plate had to be used to defend soldiers because of the bigger and more powerful ballistics used. Steel plates continued to be competitive ballistic materials even in the modern world today since advancements in steel performance continue to advance in the steel metallurgy industry.

The thickness of armor steel continued to increase since their invention, and they were able to resist a large number of anti-tank guns that were being used. The RHA steel was the commonly used steel amour during world war times; the anti-tank gun’s power was measured by how thick the rolled homogenous armor it could penetrate. The steel armor was used continuously despite there being other types or no-steel armors. RHA was used as basic armor until the end of the Second World War where a new type of anti-tank rounds that used shaped charges instead of using high-velocity projectiles was discovered and implemented.

Specifications of Military Rolled Homogenous Armor Steel

MIL-A-12560 is a steel plate that is heat-treated and designed for good resistance and defending against any improvised explosives (Konca, Erkan pg 2). Currently, this class is used by the United States army, and the Rolled Homogenous Armor is produced as per the military standards. This steel plate class has four classes were; class one is designed to resist penetration and has a thickness of 0.25″-6″. The second class is designed to resist shocks and has a thickness of 0.25″-1.25″. The third class is not designed for vehicles and has a thickness of 2″-6″. The fourth class is for maximum resistance to all types of penetrations. Improvements have been made to this class of steel, and the lasts one has the same classes as the initial one. The steel is available in sizes to ease operation activities when dealing with the metal and allows inventory for steel plate’s thickness of as low as 0.100″.

MIL-DTL-46177 is a heat-treated plate formed with a higher hardness than that of MIL-A-12560 grade with a thickness that ranges from 0.125″-0.250″. This class has similar specifications as the AR500 in terms of yield strength and tensile. However, this class was inactivated and all designed set to use MIL-DTL-12560.

Armor Steel Properties changes and deformations

Rolled homogenous Armor steel, which can also be termed ballistic steel, is used by the army to armor their vehicles to protect army personnel from incoming projectiles from external threats. The steel of high hardness, ductility, and tensile strength are the ones used to construct the ballistic plate. The tensile strength and yield strength for this ballistic has to be over 1250MPa and 1000MPa, respectively. High Hardness Armor steels (HHA) are the most commonly used armor steels, and the USA military standard outlines their properties. Armor steel is used for vehicle armoring, and the reason why it is commonly used is because of the mechanical properties that metals have. The steel armors are formed to protect a given area, and the practical weight is determined by areal density. To calculate the areal density, the armor steel’s total weight is divided by the size of the areal being protected. Steel is quite affordable compared to other materials, and it protects real-time areal density.

Amour steel structure consists of a low alloy of high strength treated to make a super resistance material to any penetrations (Gür, A. K., et al. pg5). Manufactures achieve this high resistance by the process of the thermo- mechanical form of treatment. The magnitude of this armor’s effectiveness increases as the material gets harder, but tough armor steel materials tend to be brittle and shatter easily when hit. The hardness of armor steel determines its performance, although there is no correlation between resistance, any perforations, and performance according to the ballistic limit. Studies have shown that heat treatment and alloying and commonly used to improve the resistance level of steel. Another vital property of steel for armoring is toughness (Xing, Boyang, et al. pg 8). Generally, it is considered that tough steels perform well in resisting any penetration impact without shattering, but heat treatments and alloying affect the toughness of the material.

Applications

The US Army has used rolled homogenous armor for over 80 years, and various changes have occurred on how the steel has used an armor. Advances in welding technology helped develop rolled steel plates that reduced production costs and increased the production rate. Cast steel has been used for a very long period in us army for a period of over 25 years for the M60 tank. The rolled homogenous steel came to replace the cast steel, which was expensive to produce. Based on the production cost, rolled homogenous armor continues to be the primary material used for heavy recovery and combat vehicles. Although there have been improvements in the steel processing industry, the material covered by rolled homogenous steel has not changed. In our world today, most vehicles have rolled homogenous armor as the structural base because of its toughness and strength.

The current United States army rolled homogenous armor produced by different companies as per the military’s standards, MIL-DTL-12560. Because of advances in technology, RHA’s resistance to new, improved weapons decreased. It was replaced by composite armor, a combination of materials like plastics, ceramics, and air spaces added to steel. Explosive reactive armor is another invention that has been preferred to RHA because of its high resistance properties. Historically, there have been attempts to improve steel armor to improve its hardness without making its fracture. In the 1970-the 1980s, some advancements were made, but all the ballistic structural requirements were not met. The lessons that were learned were; the Rockwell c hardness hard steel armor plates could not withstand the rounds a full-scale-caliber kinetic energy impact; the hardened steel had to show a v-notch Charpy impact that was greater than 20ft-lb at -40 degrees Celsius (McDonald, B., et al. np); it was not easy to achieve a higher performing material by reducing the steel plate thickness.

Conclusion

Vehicle armoring is commonly used in the military to enable vehicles to withstand the impact of shells, bullets, or missiles to protect the army members from being attacked by their enemies. Special steel has to be used to armor army ships, aircraft, fighting vehicles, and tanks. The United States army introduced the homogenous steal over 80 years back when they developed the first tank. The tanks were constructed to have low carbon and had a composition of special medium alloy steels. MIL-A-12560 is a steel plate that is heat-treated and designed for good resistance and defending against any improvised explosives. Currently, this class is used by the United States army, and the Rolled Homogenous Armor is produced as per the military standards. This steel plate class has four classes were; class one is designed to resist penetration and has a thickness of 0.25″-6″. The current United States army rolled homogenous armor produced by different companies as per the military’s standards, MIL-DTL-12560. Because of advances in technology, RHA’s resistance to new, improved weapons decreased. It was replaced by composite armor, a combination of materials like plastics, ceramics, and air spaces added to steel.

Works cited

Evans, William, et al. “Feasibility of Joining Wrought Homogenized Armor Steel with Friction Stir Welding.” Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium.

Gür, A. K., et al. “Investigation of Microstructure and Microhardness Behaviour of Heat-Treated Ramor 500 Armor Steel.” 8th International Advanced Technologies Symposium Elazığ, 19-22 Oct. 2017.

Hadjioannou, Michalis, and Matt Barsotti. “PHYSICAL TESTING AND MODELING OF BOLTED AND WELDED CONNECTIONS FOR ARMORED VEHICLE MODELS.” (2017).

Konica, Erkan. “A Comparison of the Ballistic Performances of Various Microstructures in MIL-A-12560 Armor Steel.” Metals 10.4 (2020): 446.

McDonald, B., et al. “Evaluation of constituitive models for predicting the deformation and rupture behaviour of armour steel under localised blast loading.” Proc. 25th Mil. Asp. Blast Shock. The Hague (2018).

Xing, Boyang, et al. “Analysis of the mass of behind-armor debris generated by RHA subjected to normal penetration of variable cross-section EFP.” Defence Technology 15.3 (2019): 390-397.