Ballistic steel is made to protect against an external threat from incoming projectiles. There is a range of steels that can be used in armor applications such as Hadfield steel and stainless steel, however, ballistic steels are hardened using the compounds iron and carbon. The extreme strength of ballistic steel is generally achieved by different amounts of carbon or other alloying elements and specialized heat treatment processes.
The Heat Treatment Process
The heat treatment process of ballistic steel generally consists of hardening and sometimes tempering, depending on the grade. To harden, the ballistic steel is heated to a temperature at which the cubical iron crystals change from their room temperature form as a ferritic structure to austenitic structure. The temperature at which this takes place is usually in the range of 700-900°C with respect to the alloying content and equipment used.
Once the steel has reached the austenitic state, the steel is rapidly cooled down in a process known as quenching. This rapid cooling freezes in the solid state solution of carbon atoms in the iron matrix and creates twisted ferritic cubical crystals. These crystals give the ballistic steel an extremely high strength.
Tempering can also be used as a heat treatment process for ballistic steel to make it more ductile, less likely to crack under fatigue, and more formable in a cold state.
Classes and Uses of Ballistic Steel
One type of ballistic steel is blast protection steel, which is in the range of 370-460 Brinell and is expertly designed to safeguard against high energy impacts, mines, grenades, and improvised explosive devices.
Ballistic steels are also used for the floor in armored vehicles as they can maintain the most extreme levels of integrity and protection in a vehicle. The floor or hull section is made of one section of wide plate, they can be bent in strong, long presses and generally formed into a V shape.
Testing Ballistic Steel
Ballistic steels must be extremely tough to absorb high impact blast energy. It is challenging to undertake blast tests that are realistic, so to confirm the material impact toughness, testing at minus 40°C is the most frequent means of testing and comparing blast protection steels. Steels are generally referred to as blast classes, with carbon content varying between 0.12 – 24%.
Ballistic Steel from Masteel
At Masteel, we manufacture ballistic steel in two different grades. Our material is extremely high quality and specification with high tensile strength. Our ballistic steel is formed under a direct quenching process which allows for good blast and ballistic protection as well as excellent surface flatness and dimensional accuracy.
Our protection 400 ballistic steel grade is suitable for high protection against the extreme pressures formed by blasts and explosions. This ballistic steel is well suited to military vehicles, security vehicles, walls and bank vaults.
Our protection 500 ballistic steel grade is optimum for protecting against projectile armaments such as airborne ballistics. This material is weldable, however it is recommended that the plates are cut with laser or plasma.