Composition
Armoured steel must be hard yet impervious to shock in order to resist high velocity metal projectiles. Steel with these characteristics is produced by processing cast steel billets of appropriate size and then rolling them into plates of required thickness. Hot rolling homogenizes the grain structure of the steel, removing imperfections which would reduce the strength of the steel. Rolling also elongates the grain structure in the steel to form long lines, which enable the stress under which the steel is placed when loaded to flow throughout the metal, and not be concentrated into one area.
RHA is called homogeneous armour because its structure and composition is uniform throughout its section. The opposite of homogeneous steel plate is face-hardened steel plate, where the face of the steel is composed differently to the substrate. The face of the steel, which starts as an RHA plate, is hardened by a heat-treatment process.
Read more about this topic: Rolled Homogeneous Armour
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