Stellite

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.

Number of Stellite alloys and their intended applications. The alloy currently most suited for cutting tools, for example, is Stellite 100, due to the fact that 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.

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 saw teeth, hardfacing (wear-resistant welding), poppet valves and seats in internal combustion engines and also in acid resistant.

Applications machine gun barrels (starting from the chamber) are lined with stellite. Modern jet engine turbine blades are usually made of stellite alloys, due to their very high melting points and tremendous strength at very high temperatures.

In the early 1980s, experiments were done in the United Kingdom to 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 steel tools and even some HSS tools, especially against difficult materials 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.