Titanium has acquired a somewhat legendary reputation in the past decade and a half. Relatively unknown by the general public until the early ‘aughts, it became a marketing tool to add a “cool factor” to everything from credit cards to golf clubs. Due to the hype, many folks assume that Titanium equates to invulnerability.
However, the truth is, Ti has very specific properties that give it an advantage in certain narrow uses. Roughly half the weight of steel, it has a better strength to weight ratio. It has 60% more density than aluminum. What this means is that titanium on a per-volume basis is inferior to steel, but will be lighter.
The most common alloy is designated 6-4, (also known as Ti6Al4V), which contains 6 points of Aluminum and 4 points of Vanadium. The alloying elements improve both the ultimate tensile strength and the hardness. Even alloyed, however, Ti is unable to achieve significant hardness compared with steel.
Titanium is also highly resistant to corrosion, and is used extensively in salt water environments. This is actually due to a very durable corrosion layer (Titanium Oxide) that forms very quickly when Titanium is scratched. Non-magnetic, Titanium finds use in mine probes.
As armor, Titanium works well in certain applications. As lightweight trauma plates in concealable soft armor, it is nearly unrivaled. In thicknesses of 2.1mm, it exhibits standalone level IIIA performance, and has no issue with rust. As rifle armor, it leaves much to be desired.
Against pistol bullets, Titanium performs well because of its combination of tensile strength and toughness. Rifle bullets, because of their high velocity and small frontal area, punch through Titanium more easily than an equivalent thickness of still. A titanium rifle plate would need to have a thickness of 11mm to be equivalent to a level III steel plate. This would be extremely expensive, compared to steel, since titanium is currently about 14 times more expensive than steel. Though there are some manufacturers that currently make titanium containing rifle plates, they are hybrids, with a steel strike face. The titanium then functions as a backing material, where its properties are more appropriate.
In vehicle armor, Titanium has gained greater acceptance, simply because it can be utilized in thicker cross section. In this application, it is superior to steel in many ways- it is much lighter, and corrosion resistance. In thicker section, its resistance to typical threats faced by vehicles is impressive.
To sum it up: titanium is a good choice as trauma plates for soft armor vests, but there are better options for use in rifle plates.
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