There are 2 spellings for armor. One without the u, “armor”, which is American, and one with the u, “armour”, which is British.
Not-with-standing the spelling, armor plates have been used for over 3000 years. It began with leather and evolved through various reinforced woods to steel and modern composites such as Kevlar and ceramics. The goal of all developments in Armoring is to provide greater protection using the “lightest” materials available.
How Armor Plates Are Used Today
There are many objectives in the manufacturing of modern weapons. In the case of projectiles (bullets), the objective is to increase the penetration of the latest armor materials. On the other hand, armor manufacturers seek to stop penetration of the latest projectiles while reducing weight and increasing mobility. As an example, increasing the thickness of steel plate used in vehicles and tanks will eventually stop penetration of today’s projectiles, but the vehicle/tank will become so heavy that mobility is reduced to almost zero.
Apart from recent developments of composites, which tend to be very expensive, the manufacturers of armor plates have concentrated on changing the chemistry of the steel and the parameters of production. An example of note is that by adding more carbon, the steel will increase in hardness, but also become more brittle. The methods used to cool the plates (i.e. Quench and Temper) with water, oil or air, affects the hardness and yield strength. As such, the gentle balance of strength and durability in creating armor plates is an ever changing “Tug of War”.