Because boron carbide is highly rigid, lightweight, and difficult to destroy, it is ideal for body armor, and these inherent advantages make body armor very comfortable for soldiers, police, security personnel, and others.
Although boron carbide ceramic can effectively resist the impact of pistol bullets, smoothbore bullets and slower rifle bullets, it still has a very prominent problem – when the boron carbide material is driven at speeds above 900 m/s (2,950 ft/s) A phase transition occurs when an object hits, causing its strength to drop significantly
The M855 5.56mm bullet has a burr velocity of up to 3,113 ft/s, and while this velocity drops rapidly at higher ranges, at shorter ranges, like the M855 bullet, it activates the phase transition of boron carbide body armor.The wearer man has the risk of body armor failure.