L-605 is a cobalt-chromium-tungsten-nickel alloy and is typically double melted to remove impurities.
L-605 alloy is a nonmagnetic, cobalt-chromium-tungstennickel alloy. The high strength properties of this alloy may be obtained through work hardening. It remains nonmagnetic in the work-hardened condition.
The alloy is normally solution-treated in the range of 2150ºF-2250ºF (1175ºC-1230ºC), then rapid air cooled or water-quenched to attain optimum properties. Annealing at lower temperatures may cause some precipitation of carbide, which is undesirable for the achievement of many properties.
L-605 has good oxidation and corrosion resistance as well as excellent high strength properties at elevated temperatures. The alloy is typically used in the cold-worked condition. A modest increase in hardness and strength can be achieved through aging of the cold worked material. End uses in the medical field are stents, bone drill bits, cerclage cables, guide rods, orthopaedic cables, heart valves and various other orthopaedic applications.
Cobalt based alloys develop a highly polished appearance as they are drawn to fine diameters. Surface roughness can be reduced when processed using single crystal natural diamond dies. Diameters over 0.040" will not have as smooth a finish because of poly-crystal line dies. Diameters over 0.070" will be carbide drawn and supplied with a more textured surface. Additional finish treatments can enhance the surface of the wire. Material above 0.070" is often centerless ground and polished when supplied as straightened and cut bar. This process yields a lustrous surface finish and maintains a tight tolerance for precision machining applications.
L-605 is machinable using conventional techniques; however cobalt grades of high-speed steel or carbide tools combined with right machine setups are recommended. L-605 is more difficult to machine than the austenitic stainless steels (e.g.Types 302, 304, 321, and 347 stainless). Generally, lower feed speeds and depths of cut are suggested. A very high workhardening rate, generation of heat during cutting and a high shear strength complicate machining.