Alloy 6B / UNS R30016 / AMS 5894
Description
Alloy 6B is a cobalt-based alloy with great wear, erosion and abrasion resistance. The wear resistance of alloy 6B is due to the chemical composition and is not a product of heat treatment or other hardening mechanisms. The low coefficient of friction of alloy 6B allows it to resist seizing and galling; proving useful in areas and applications where lubrication is difficult or impractical. Even under constant erosive conditions, alloy 6B has shown exceptional cavitation erosion resistance. Elevated temperature exposure has little effect on this alloy’s hardness, impact strength, and dimensional stability. Alloy 6B also maintains high hardness at elevated temperatures (approaching 2000°F) and will recover its original hardness upon cooling to room temperature. This unique property, coupled with good corrosion resistance to a multitude of media and superior mechanical properties in relation to its outstanding wear resistant characteristics, makes alloy 6B a versatile alloy that can be used in numerous applications where wear, corrosion and elevated temperature are concerns.
Industries & Applications
Alloy 6B is suitable for use in a variety of high wear and erosion applications. The abrasion resistance of this alloy allows it to be used as industrial scraper blades and knives in the food processing, waste water treatment and textile industries. Alloy 6B is used in applications where erosion is an issue such as nozzles, pumps, valves and mixing blades that are moving slurries where cavitation damage is a concern. This alloy has also found use in industrial sliding wear applications such as valves in chemical processing and turbine blade components for steam control in the power industry. Alloy 6B can also be found in bearing assemblies in heat treat furnaces.
Resistance to Corrosion
Alloy 6B also has corrosion resistance in a variety of media in addition to being wear resistant. Chromium, molybdenum, tungsten and nickel all provide additional resistance against corrosion. Alloy 6B is very resistant to oxidation at ambient temperatures and has good resistance to oxidation at elevated temperatures. Alloy 6B is resistant to different aqueous corrosive media at various concentration and temperature combinations. See the table on the next page for specifics.
Fabrication and Heat Treatment
The carbon content in alloy 6B may make it more difficult to machine compared to other cobalt based alloys, but tungsten carbide tools can still be used to machine this alloy. High speed inserts are not recommended but EDM techniques can be used to make threads in this alloy. Alloy 6B can be welded using a range of methods, including TIG, MIG, shielded metal arc and coated electrode welding. A preheat treatment to 1000°F should be used and maintained to prevent cracking during welding. Ventilation is needed to minimize exposure to airborne dust, fumes, and particulate matter when machining, grinding or welding this alloy. The standard heat treatment for alloy 6B is 2250°F (1232°C) followed by an air cool.
Common Trade Names
Stellite® 6B
Stellite® is a registered trademark of Deloro Stellite Company.
