Cobalt based metals are alloyed with chrome, nickel, and tungsten. Due to the high cost of these alloys, they are used where severe conditions prevail and require high temperature strength and hardness, excellent wear, galling, corrosion, and/or erosion resistance.
Due to the high chromium content (25% - 30% for the grades listed below) cobalt-based alloys provide superior corrosion resistance at high temperature. The materials are more weldable than nickel-based alternatives. While not as strong as nickel alloys at lower temperatures, above about 1700°F / 930°C cobalt alloys show higher strength. Nickel melts at 2651°F / 1455°C while cobalt melts at 2723°F / 1495°C.
There is also data to demonstrate that casting processes which solidify directionally (centrifugal, for example) lead to improvements in rupture strength and thermal fatigue resistance.
Common cobalt-based grades include: MTEK 6 / R30006, MTEK 21 / R30021, and MTEK 31 / R 30031.
For guidance in selecting the appropriate cobalt-based alloy in your application, contact us.