Special treatment steel
Encyclopedia
Special Treatment Steel, also known as Protective Deck Plate. Originally developed by Carnegie Steel around 1910, it became the U.S. Navy Bureau of Construction and Repair (later Bureau of Ships
Bureau of Ships
The United States Navy's Bureau of Ships was established by Congress on June 20, 1940, by a law which consolidated the functions of the Bureau of Construction and Repair and the Bureau of Engineering. The new Bureau was to be headed by a Chief and Deputy-Chief, one selected from the engineering...

) standard form of high-percentage nickel steel used on all portions of a warship needing homogeneous direct impact protection armor, except gun mounts and conning towers, where Bureau of Ordnance
Bureau of Ordnance
The Bureau of Ordnance was the U.S. Navy's organization responsible for the procurement, storage, and deployment of all naval ordnance, between the years 1862 and 1959.-History:...

 Class "B" armor was used. Somewhat more ductile than the average for any similar armor, even Krupp
Krupp
The Krupp family , a prominent 400-year-old German dynasty from Essen, have become famous for their steel production and for their manufacture of ammunition and armaments. The family business, known as Friedrich Krupp AG Hoesch-Krupp, was the largest company in Europe at the beginning of the 20th...

's post-World War I "Wotan weich" armor, STS could be used as structural steel, whereas traditional armor plate was entirely deadweight. STS was expensive, but the United States could afford to use it lavishly, and did so on virtually every class of warship constructed from 1930 through the World War II era, in thicknesses ranging from bulkheads to splinter protection to armored decks to lower armor belts.

STS contained approximately 1.75-2% by weight chromium, 3-3.5% nickel, and 0.35-0.4% carbon. Unlike some similar steels, such as Krupp Ww, STS did not use molybdenum.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK