Development and Types (Sytop Stellite Alloy 12)
Stellite alloy was invented by Americans at the beginning of this century. The alloy with cobalt chrome and tungsten as the main element is silver-white after cooling, and it flashes like a star.
In 1922, Stellite alloy was used for hard-faced coatings to solve the special needs of internal combustion engines, followed by jet engines. The development of Stellite Bushing has made an important contribution to the development of aviation, automotive and high temperature chemical industries. At present, the world consumes about 1,500 tons of stellite alloy per year, and one third of it is used for surfacing welding of internal combustion engine valves and other valves.
Initially, the stellite alloy was a cobalt-chromium binary alloy, which was
later developed into a ternary composition of cobalt-chromium-tungsten. Other
elements such as carbon, silicon, nickel, etc., were originally considered as
impurity elements and were present in the alloy, and today these elements are
strictly controlled. The alloys such as stellite 1, 6, 21, etc., which are
currently used, have substantially the same composition as previously
determined. After continuous research and development, there are no more than 30
grades of stellite alloy. In addition to castings, stellite alloy is limited to
small parts such as small molds, blades, nozzles, seal rings, etc., while large
parts are coated on the work surface to save expensive stellite alloys. PTFE is
also made into products such as cast welding rods, welding rods, tubular welding
wire, and spray-welded alloy powder.
The development of stellite alloys can be divided into three series:
Co-Cr-WC series, this series is a classic Stellite alloy, which is characterized by less alloying elements and higher carbon content than stellite-7, generally above 1%, even greater than 2%. Therefore, the hardness of the alloy is relatively high.
Co-Cr-W series, this series is characterized by appropriately reducing the hardness of the alloy, improving the toughness and better comprehensive mechanical properties.
Co-Cr-W-C-Si-B series, all of which are alloy powders.
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