Protection is a system property, not a material property. A plate does not have a protection level on its own — a plate of a given grade, at a given thickness, tested against a defined threat at a defined velocity and angle, does.
What defines a protection level
- The threat. Projectile type, mass and construction. Hardened cores behave entirely differently from soft cores.
- The velocity. Stated at a defined range, because velocity falls with distance.
- The angle. Obliquity dramatically changes the outcome; a plate that stops a threat at an angle may not stop it square on.
- The criterion. What counts as a pass — no perforation, or no spall behind the plate as well.
Standards such as the STANAG and EN 1522/1063 families define these combinations. Quoting "high hardness plate" without the class, thickness and standard tells a fabricator nothing useful.
Why hardness alone is not the answer
Armour grades are hard to break up the projectile, and tough so the plate does not shatter or spall behind the point of impact. That balance is engineered in the mill's heat treatment — which is exactly what careless fabrication undoes.
Fabrication rules that protect the protection
- Cut cold where you can. Waterjet and abrasive cutting keep the heat affected zone minimal; thermal cutting creates a softened band at every edge.
- Mind the edges and joints. Joints and fixings are the weak points of any armoured structure. Overlap and back them.
- Control welding heat. Follow the mill's preheat and heat input guidance; over-tempered metal next to a weld is a hole waiting to happen.
- Do not bend tightly. Respect the minimum bend radius; cracks start at tight radii.
- Keep traceability. Transfer plate marking before cutting, and keep heat numbers on the parts.
We supply protection plate with full mill documentation, arrange cold cutting to profile, and will review the build sequence with your fabricator before anything is cut.
