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Harvey armor was a type of steel
naval armor Naval armour refers to the various protections schemes employed by warships, and is distinguished from other kinds of armour. Naval sailing ships have had protection from weaponry since at least ancient times, when Greek and Roman warships used s ...
developed in the early 1890s in which the front surfaces of the plates were case hardened. The method for doing this was known as the Harvey process, and was invented by the American engineer
Hayward Augustus Harvey Hayward Augustus Harvey (January 17, 1824 – August 28, 1893) was an American inventor and industrialist. Biography Hayward A. Harvey was born in Jamestown, New York on January 17, 1824. He was educated at the Poughkeepsie Academy and the ...
. This type of armor was used in the construction of capital ships until superseded by Krupp armor in the late 1890s. The Harvey United Steel Company was a steel cartel whose chairman was Albert Vickers. The year 1894 would see the ten main producers of armor plate, including Vickers, Armstrong,
Krupp The Krupp family (see pronunciation), a prominent 400-year-old German dynasty from Essen, is notable for its production of steel, artillery, ammunition and other armaments. The family business, known as Friedrich Krupp AG (Friedrich Krup ...
,
Schneider Schneider may refer to: Hospital * Schneider Children's Medical Center of Israel People * Schneider (surname) Companies and organizations * G. Schneider & Sohn, a Bavarian brewery company * Schneider Rundfunkwerke AG, the former owner of th ...
, Carnegie and Bethlehem Steel, form the Harvey Syndicate.


Predecessors

Before the appearance of
compound armor Compound armour was a type of armour used on warships in the 1880s, developed in response to the emergence of armor-piercing shells and the continual need for reliable protection with the increasing size in naval ordnance. Compound armour was a no ...
in the 1880s, armor plating was made from uniform homogeneous iron or steel plates backed by several inches of teak to absorb the shock of projectile impact. Compound armor appeared in the mid-1880s and was made from two different types of
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
, a very hard but brittle high- carbon steel front plate backed by a more elastic low-carbon wrought iron plate. The front plate was intended to break up an incoming shell, while the rear plate would catch any splinters and hold the armor together if the brittle front plate shattered. Compound armor was made by pouring molten steel between a red-hot wrought iron backing plate and a hardened steel front plate to weld them together. This process produced a sharp transition between the properties of the two plates in a very small distance. As consequence, the two plates could separate when struck by a shell, and the rear plate was often not elastic enough to stop the splinters. With the discovery of nickel-steel alloys in 1889, compound armor was rendered obsolete.


Production process

Harvey armor used a single plate of steel, but re-introduced the benefits of compound armor. The front surface was converted to high carbon steel by "cementing". In this process, the steel plate would be covered with
charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, cal ...
and heated to approximately 1200 degrees Celsius for two to three weeks. The process increased the carbon content at the face to around 1 percent; the carbon content decreasing gradually from this level with distance into the plate, reaching the original proportion (approximately 0.1–0.2 percent) at a depth of around an inch. After cementing, the plate was chilled first in an oil bath, then in a water bath, before being annealed to toughen the back of the plate. The water bath was later replaced with jets of water to prevent the formation of a layer of steam which would insulate the steel from the cooling effect of the water. The process was further improved by low temperature
forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die. Forging is often classified according to the temperature at which i ...
of the plate before the final heat treatment. While the American navy used nickel steel for Harvey armor (roughly 0.2 percent carbon, 0.6 percent manganese, 3.5 percent nickel), the British used normal steels since their tests had shown that ordinary steel subjected to the Harvey process had the same resistance to penetration as nickel steel, although it was not quite as tough. Harvey armor was taken up by all of the major navies, since of Harvey armor offered the same protection as of nickel-steel armor. It was in turn rendered obsolete by the development of Krupp armor in the late 1890s.


See also

* Carburizing


References

*
Gene Slover's US Navy Pages - Naval Ordnance and Gunnery
* {{Naval armour Naval armour