Naval armour
Case-hardened Harvey armor was the first major development, followed by chromium alloyed and specially hardened Krupp armour.
[1] Kuki Yoshitaka, a Japanese admiral of the same period, ordered the construction of ships armored with iron pavises called tekkōsen [ja].
Medieval Japanese vessels also used bundled bamboo taketaba to defend against bullets and small cannon shot.
[8] Ironclads were designed for several roles, including as high seas battleships, coastal defence ships, and long-range cruisers.
The rapid pace of change in the ironclad period meant that many ships were obsolete as soon as they were complete, and that naval tactics were in a state of flux.
[11] The development of the torpedo and effective naval mines required further considerations for underwater armor, which had not been given much thought in prior eras.
The World War era also saw the emergence of the armoured cruiser, which traded some armor in exchange for speed as compared to a battleship.
However, most modern warships retain 25 to 50 mm (0.98 to 1.97 in) of partial armor to protect missiles and aircraft from splinters and light weapons fire.
It is designed to keep the ship afloat even if the hull was struck underneath the belt armour by a shell or by a torpedo.
After the lessons learned during World War I, many capital ships were refitted with double, triple, or even quadruple torpedo bulkheads, as well as anti-torpedo bulges to the exterior of the hull.
It consisted of a series of lightly armoured compartments, extending laterally along a narrow belt that intersected the ship's waterline.
In theory this belt would absorb the explosions from torpedoes, or any naval artillery shells that struck below the waterline, and thus minimize internal damage to the ship itself.
The U.S. Navy adopted what was formally called "all or nothing" armour in the Standard-type battleships, starting with the Nevada class laid down in 1912.
While cast iron has never been used for naval armour, it did find a use in land fortifications, presumable due to the lower cost of the material.
Among its members was Sir William Fairbairn, a noted civil and structural engineer who had also built over 80 iron vessels before retiring from shipbuilding.
This committee worked four years, between 1861 and 1865, during which time it formulated the best performing armour with the metallurgy as then known, suggested ways for improving its production and quality and helped develop more effective shot against ironclad vessels.
However, when the Special Committee tested both types of plate in 1863, it found that rolled iron was superior to hammered due to greater uniformity in quality.
The committee and iron manufacturers worked together on how to more easily produce rolled plate, which became standard use in warships beginning in 1865.
Many ships made during the American Civil War used laminated armour but this was necessitated by lack of facilities for manufacturing single plates of proper thickness.
The year 1894 would see the ten main producers of armor plate, including Vickers, Armstrong, Krupp, Schneider, Carnegie and Bethlehem Steel, form the Harvey Syndicate.
[23] The manufacturing process remained largely the same, with slight changes in the alloy composition: in % of total – carbon 0.35, nickel 3.90, chromium 2.00, manganese 0.35, silicon 0.07, phosphorus 0.025, sulfur 0.020.
This increased elasticity greatly reduced the incidence of spalling and cracking under incoming fire, a valuable quality during long engagements.
Ducol or "D"-steel is the name of a number of high-strength low-alloy steels of varying composition, first developed from the early 1920s by the Scottish firm of David Colville & Sons, Motherwell.
Ducol has been used for bulkheads in both general construction and against torpedoes, and for light armour in warships of several countries, including the British, Japanese and perhaps Italian navies.
[28] A solution was found by using rivets to attach the welded Ducol substructures to the hull rather than the original all-welded construction, allowing for some 'give'.
According to Nathan Okun, the King George V-class battleships had the simplest armour arrangement of all post-WWI capital ships.
[citation needed] Other types of armour used on Navy ships: The Imperial Japanese Navy (IJN) made considerable use of Ducol made under licence by Japan Steel Works in Muroran, Hokkaidō, Japan: the company was set up with investment from Vickers, Armstrong Whitworth and Mitsui.
"[37] In addition, the IJN's '25-ton' type river motor gun boat had an all-welded hull, protected by 4-5mm Ducol steel.
Plastic armour replaced the use of concrete slabs which, although expected to provide protection, were prone to cracking and breaking up when struck by armour-piercing bullets.
[43] Electrically charged armour is a recent development in the United Kingdom by the Defence Science and Technology Laboratory.
