An Armour piercing shell is a type of ammunition designed to penetrate armour. In naval warfare and older anti-tank shells, the shell had to withstand the shock of punching through armour plate. Shells designed for this purpose had a greatly strengthened case with a specially hardened and shaped nose, and a much smaller bursting charge. Some smaller calibre AP shells had no bursting charge at all. Plain AP shell is now very rarely seen except in naval usage, and is not commonly used there. 5. ... Naval warfare is combat in and on seas and oceans. ... Anti-tank, or simply AT, refers to any method of combating military armored fighting vehicles, notably tanks. ... A shell is a projectile, which, as opposed to a bullet, is not only shot by explosives, but also contains explosives itself. ... Alternative meanings: vehicle armour, Armor (novel) A hoplite wearing a helmet, a breastplate and greaves (and nothing else). ... The word caliber (American English) or calibre (British English) designates the interior diameter of a tube or the exterior diameter of a wire or rod. ...

History

On the introduction of ironclad warships in the late 19th century it was found that the ordinary cast-iron projectile readily pierced the thin plating, and in order to protect the vital parts of the vessel wrought iron armour of considerable thickness was placed on the sides. It then became necessary to produce a projectile which would pierce this armour. This was effected by Sir W. Palliser, who invented a method of hardening the head of the pointed cast-iron shot. By casting the projectile point downwards and forming the head in an iron mould, the hot metal was suddenly chilled and became intensely hard, while the remainder of the mould being formed of sand allowed the metal to cool slowly and the body of the shot to be made tough. Ironclad warships, frequently shortened to just ironclads, were ships sheathed with thick iron plates for protection. ... Cast iron usually refers to grey cast iron, but can mean any of a group of iron_based alloys containing more than 2% carbon (alloys with less carbon are carbon steel by definition). ... Wrought iron is a very pure form of commercial iron, having a very small carbon content. ...

These shot proved very effective against wrought-iron armour, but were not serviceable against compound and steel armour. A new departure had, therefore, to be made, and forged steel shot with points hardened by water, took the place of the Palliser shot. At first these forged steel shot were made of ordinary carbon steel, but as armour improved in quality the projectiles followed suit, and, for the attack of the latest type of cemented steel armour, the projectile is formed of steel -- either forged or cast -- containing both nickel and chromium. Tungsten and steel shot were also used with success. Steel framework Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ... Carbon steel is a metal, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties. ... This article is about the element nickel. ... General Name, Symbol, Number chromium, Cr, 24 Chemical series transition metals Group, Period, Block 6 (VIB), 4, d Appearance silvery metallic Atomic properties Atomic weight 51. ... General Name, Symbol, Number Tungsten, W, 74 Chemical series Transition metals Group, Period, Block 6 (VIB), 6, d Density, Hardness 19250 kg/m3, 7. ...

These pre-WWI Armour-piercing shot or shell were generally cast from a special mixture of chrome and steel that was melted in pots. They were afterwards forged into shape and then thoroughly annealed, the core bored and the exterior turned up in the lathe. The shells were finished in a similar manner to others described below. The final, or tempering, treatment was very important, and was a closely guarded secret. It consisted of hardening the head of the projectile and tempering it in a special manner, the rear portion being reduced in hardness so as to render it tough. The cavity of these projectiles was capable of receiving a small bursting charge of about 2% of the weight of the complete projectile, and when this is used the projectile is called an armour-piercing shell. The shell, whether fuzed or unfuzed, will burst on striking a medium thickness of armour. Armour-piercing shells of this period had a bursting charge of about 3% of the weight of the complete projectile, and were often fitted with a soft steel cap for the perforation of hard steel armour. Ypres, 1917, in the vicinity of the Battle of Passchendaele. ... Chrome may refer to: (most commonly) chrome plating where the element chromium is fixed to a surface (in computer science) the chrome of an application, i. ... The word anneal has several meanings: In metallurgy and materials science annealing is a heat treatment wherein the microstructure of a material is altered, causing changes in its properties such as strength and hardness. ...

Even with these improvements the projectile was not, with a reasonable velocity, able to pierce one calibre in thickness of cemented steel armour.

References

• This article incorporates text from the public domain 1911 Encyclopædia Britannica.