Ballistic steel, as the name suggests, is designed to protect against incoming projectiles. Under the umbrella of steel, there are multiple types of steel that can be used in applications like armor, including Hadfield steel and stainless steel. However, the extreme strength of ballistic steels is unmatched by such alternatives.
Ballistic steels are hardened during the production process using iron and carbon compounds. The notable strength of ballistic steel is typically achieved by different amounts of carbon - or other alloying elements - as well as specialized heat treatment processes.
Heat Treatment: The Process
The process of heat treatment in the production of ballistic steel is comprised of both hardening and tempering, depending on the grade of the steel.
Suppose the process is hardening rather than tempering. In that case, the ballistic steel is heated to a specific temperature at which the form of the cubical iron crystals changes from being a ferritic structure (at room temperature) to an austenitic structure (when heated).
Typically, this occurs at temperature ranges of 700-900 °C, depending on the alloying content and equipment that has been used.
In a process called ‘quenching’, the steel is rapidly cooled once it has reached the austenitic state. This process of rapid cooling creates twisted ferritic cubical crystals by freezing in the solid state solution of carbon atoms in the iron matrix. It is these crystals that give the ballistic steel its extremely high strength.
Another heat treatment process for ballistic steel is tempering, which can be used to make ballistic steel more formable in a cold state, less likely to crack under fatigue and more ductile.
Classes and Uses of Ballistic Steel
Blast protection steel is one particular type of ballistic steel, which is within the 370-460 Brinell range. Blast protection steel has been expertly designed to protect against high-energy impacts, grenades, mines and improvised explosive devices.
Ballistic steels are also used as the floor in armored vehicles, given that they can maintain integrity and protection even in the most extreme environments. The floor or hull section is made of one section of wide ballistic steel plate, which can then be bent in strong, long presses and typically formed into a V shape.
Ballistic Steel Testing
Of course, it goes without saying that in order to absorb high impact blast energy, ballistic steels must be extremely tough.
Realistic blast tests that mimic a likely environment can be difficult, so to determine the material impact toughness, the material is often tested at minus 40 °C - the most frequent means of testing and contrasting blast protection steels.
Steels are generally referred to within ‘blast classes’, with respective carbon contents varying between 0.12 – 24%.
Masteel’s Ballistic Steel
Masteel manufactures two different grades of ballistic steel, all of which is made to an extremely high quality and specification and with good tensile strength.
A direct quenching process is used to form Masteel’s ballistic steel, allowing for strong blast and ballistic protection as well as notable surface flatness and dimensional accuracy.
Masteel’s protection 400 ballistic steel grade is ideal for high protection use against the extreme pressures formed by blasts and explosions and is, therefore, naturally well-suited to use in security vehicles, military vehicles, bank vaults and walls.
Masteel’s protection 500 ballistic steel grade is ideal for protecting against missile armaments such as airborne ballistics. It is recommended that the plates are cut with laser or plasma, even though this material is weldable.
This information has been sourced, reviewed and adapted from materials provided by Masteel UK Ltd.
For more information on this source, please visit Masteel UK Ltd.