Stellite alloy is a range of
cobalt- chromium alloys designed for wearresistance. It may also contain tungstenand a small but important amount of carbon. It is a trademarked nameof the Deloro Stellite Company and was invented by Elwood Haynes[ [http://www.wpi.edu/News/Conf/Roundtable/Barcelona/alumni.html "The WPI International Corporate Leaders Roundtable: The Impact of Evolving Technologies on the Future of Business: Notable Achievements of Alumni of Worcester Polytechnic Institute"] . Elwood Haynes, Class of 1881.] in the early 1900s as a substitute for flatwarethat stained (or that had to be constantly cleaned).
Stellite alloy is a completely non-magnetic and non-corrosive cobalt alloy. There are a number of Stellite alloys, with various compositions optimised for different uses. Information is available from the manufacturer, Deloro Stellite, outlining the composition of a number of Stellite alloys and their intended applications. The alloy currently most suited for cutting tools, for example, is Stellite 100, because this alloy is quite hard, maintains a good cutting edge even at high temperature, and resists hardening and annealing due to heat. Other alloys are formulated to maximize combinations of
wear resistance, corrosion resistance, or ability to withstand extreme temperatures.
Stellite alloys display astounding hardness and
toughness, and are also usually very resistant to corrosion. Stellite alloys are so hard that they are very difficult to machine, and anything made from them is, as a result, very expensive. Typically a Stellite part will be very precisely cast so that only minimal machining will be necessary. Machining of Stellite is more often done by grinding, rather than by cutting. Stellite alloys also tend to have extremely high melting points due to the cobalt and chromium content.
Typical applications include
sawteeth, hardfacing, and acid-resistant machine parts. Stellite was a major improvement in the production of poppet valves and valve seats in internal combustion engines; by reducing wear in them, the competing slide-valve design was driven from the market. The first third of M60 machine gunbarrels (starting from the chamber) are lined with Stellite. In the early 1980s, experiments were done in the United Kingdomto make artificial hip joints and other bone replacements out of precision-cast Stellite alloys.
Stellite has also been used in the manufacture of turning tools for lathes. With the introduction and improvements in
tipped tools it is not used as often any more, but it was found to have superior cutting properties compared to the early carbon steeltools and even some high speed steel tools, especially against difficult materials such as stainless steel. Care was needed in grinding the blanks and these were marked at one end to show the correct orientation, without which the cutting edge could chip prematurely.
While Stellite remains the material of choice for certain internal parts in industrial process valves (valve seat hardfacing), its use has been discouraged in nuclear power plants. In piping that can communicate with the reactor, tiny amounts of Stellite would be released into the process fluid and eventually enter the reactor. There the cobalt would be activated by the
neutron fluxin the reactor and become cobalt-60, a radioisotope with a five year half lifethat releases very energetic gamma rays. While not a hazard to the general public, about a third to a half of nuclear worker exposures could be traced to the use of Stellite and to trace amounts of cobalt in stainless steels. Replacements for Stellite have been developed by the industry, such as the Electric Power Research Institute’s “NOREM”, that provide acceptable performance without cobalt. Since the United States nuclear power industry has begun to replace the Stellite valve seat hardfacing in the late 1970s and to tighten specifications of cobalt in stainless steels, worker exposures due to cobalt-60 have dropped significantly.
Talonite is an alloy similar to Stellite which has been hot-rolled and hardened in a particular way, to provide a combination of hardness, wear resistance and machinability. Not all Stellite alloys respond to this process.
* [http://www.armstrongblue.com/Publications/msds__stellite_tips.htm Material Safety Data Sheet for stellite] , includes table of compositions of individual variants
* [http://www.stellite.com Deloro Stellite company website]
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Stellite — Stellite® ist ein markenrechtlich geschützter Name der Deloro Stellite Holdings Corporation für Hartlegierungen auf Cobalt Chrom Basis. Heute werden sie als Nichteisenlegierungen geführt, jedoch ist aus den 1950er Jahren auch Stellite mit bis zu… … Deutsch Wikipedia
stellite — [ stelit ] n. m. • 1923; n. déposé , probablt du lat. stella « étoile » ♦ Techn. Alliage à haute teneur en cobalt (plus de 40%), contenant du chrome, du tungstène, etc. Les stellites sont utilisés pour recouvrir les pièces soumises à la chaleur… … Encyclopédie Universelle
Stellite — [stel′īt΄] trademark for any of a group of cobalt chromium superalloys characterized by great hardness and resistance to corrosion at high temperatures, used in making jet engine parts, cutting blades, etc. n. [s ] any such superalloy * * * … Universalium
Stellite — [stel′īt΄] trademark for any of a group of cobalt chromium superalloys characterized by great hardness and resistance to corrosion at high temperatures, used in making jet engine parts, cutting blades, etc. n. [s ] any such superalloy … English World dictionary
Stellite — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. Stellite est l ancien nom de la pectolite. un appareil amovible permettant la fixation de prothèse dentaire, appelé aussi châssis métallique. une gamme d… … Wikipédia en Français
stellite — stelitai statusas T sritis chemija apibrėžtis Co kietlydiniai, turintys iki 35% Cr, o taip pat W, Mo, Ni, Fe, C, B. atitikmenys: angl. stellite rus. стеллиты … Chemijos terminų aiškinamasis žodynas
stellite — (stèl li t ) s. f. Minéral d Écosse, cristallisant en étoiles. ÉTYMOLOGIE Lat. stella, étoile … Dictionnaire de la Langue Française d'Émile Littré
Stellite — Stel·lite (stelґit) (stelґlīt) trademark for any of a group of nonferrous, very hard, noncorrosive alloys composed chiefly of cobalt and chromium, with or without small amounts of other metals added. Used especially in the manufacture of… … Medical dictionary
stellite — Смотри Стеллиты … Энциклопедический словарь по металлургии
Stellite — Stel·lite … English syllables