Steels that protect against external threats from incoming projectiles – bullets, blast debris, etc – are called armour protection, or ‘ballistic protection’ steels.
The constituent chemicals in such steels are iron (Fe) and Carbon (C). The ‘hardness’ required is a result of the mix of varying amounts of carbon and another alloying element like chromium, nickel, or molybdenum, a combination of which is then put through a specialised heat treatment process.
The heat treatment process can be either ‘hardening’ or ‘tempering’. The first is achieved by heating the steel until the cubic iron crystals, which have a ferritic structure at room temperature, to their high-temperature form as austenitic structure (>900C).
This mixture is then quenched to cool it rapidly to nearly room temperature, which is how it is forced to remain in the solid-state solution of carbon atoms in an iron matrix which forms the twisted ferritic cubical crystals that end up with a very high strength.
Tempering steel, which is dying out as a process, is done when you want a more ductile product that is more formable in a cold state and less sensitive to cracking. The improvements in steel manufacturing technologies have made it possible to make steels that are lower in impurities.
Generally, armour steels are defined by their ‘hardness’ factor, which in most cases is measured against the Brinell Hardness scale, which is a number proportional to the load or test force of a hard steel ball to the calculated curved area of the indentation formed. The ball diameter used can be 1mm, 2.5mm, 5mm, or 10mm.
Owing to its high impact strength and low susceptibility to pressures and blasts, ballistic steel is most commonly used in military applications but, increasingly, this metal is not confined to martial applications, and its extreme properties offer benefits to a wider range of industries and sectors.
Financial and governmental buildings
Banks and government buildings related to the financial sector are increasingly being built or retrofitted with the tough physical protections afforded by the inclusion of ballistic steels. Bank counters are being designed to increase protection for personnel from a variety of ballistic events – knives, bullets, blasts – with armoured steel pneumatic screens that can seal counter windows in less than a second.
This level of protection is now being planned for payment counters in commercial areas with a large cash amounts volume, like petrol stations, kiosks, bureaux des changes, and more.
Principles learned in the military arena have been applied to private security for decades. Whether it is tactical and strategic training of personnel, the equipment, and machinery used to protect clients ranging from the super-rich industrialists, senior government officials, to C-Suite workers in global corporations and celebrities, the mindset is of almost paramilitary level.
The latest surveillance avoidance and detection systems, armoured vehicles in all shapes and sizes, and body protection equipment use state-of-the-art systems and materials to form a defensive perimeter around those that can afford it.
Domestic applications for armoured steel are becoming more popular, with residential properties being designed or remodelled with steel panels, doors, window frames, and other home fittings to improve their security.
The addition of this material can offer increased peace of mind to any property owner against risks of burglary, home invasion, or related crimes.
Policing and civil defence
Criminals are becoming more sophisticated and violent, so police forces around the world must stay ahead of defensive systems to protect themselves and the public they are sworn to protect. Apart from ensuring all the weapons systems and ballistic protective gear in the shapes of bulletproof helmets, shields, and body armour, while police vehicles are also being built with armoured plate steel components.
Another key element in their arsenal is strong blast-proof structures – buildings, guard posts, and jails to name a few – at having ballistic plates, enclosures, and counters.
SSAB completed a project, supplying Ramor 500 protection plates (2000mm x 1500mm) to Cherpin, a French construction company in 2021. The company used the plates in the construction of a perimeter protection fence around the new police station in Villefranche-sur-Saone, France.
The laser-cut panels were placed in U-profile grooves in the hardened concrete base/wall uprights, and then secured in place using bolts. The finish of the completed structure was thermal-lacquering paint, applied at 170°C.
Another world-famous historical structure built with SSAB protection steels is the Swedish embassy, which is within the grounds of The House of Sweden in Washington DC, USA. The entire complex is protected by varying grades and thicknesses of steel plates in its walls, doors, windows, and other areas, making it a safe and secure place for employees, residents, and visitors.