Rolled Homogeneous Armour - History

History

From the invention of tanks through to the Second World War, tank armour increased in thickness to resist the increasing size and power of anti-tank guns. A tank with sufficient armor could resist the largest anti-tank guns then in use.

RHA was common use during this period (combined with other plate alloys and cast steel armor), and the measure of the power of an anti-tank gun was the thickness of RHA it would penetrate. This measure of tank gun effectiveness has remained in use because it is a useful universal measure for the comparison of increased anti-tank gun effectiveness. Different types of armour, some of which do not use steel or even metals, have come into use but depth of penetration of RHA is still used to compare anti-tank weapon effectiveness.

RHA was in common use as the primary armor system until after World War II. A new generation of anti-tank rounds had come into use during World War II which did not use a heavy, tough, high-velocity projectile to defeat steel armour but instead used an explosive charge called a shaped charge to overcome the strength of the steel. The strength, toughness and hardness of RHA was no longer protection against this threat.