Stellite 21
R30021Low-carbon cobalt-chromium-molybdenum alloy optimized for cavitation, galling, and corrosion resistance rather than abrasive wear. CoCrMo matrix without tungsten — Mo replaces W for superior corrosion resistance in reducing environments. Lower hardness (25-35 HRC) than Stellite 6 but better ductility and thermal/mechanical shock resistance. Used for valve seats in corrosive service, pump components in chemical processing, hot gas path components, and nuclear valve hardfacing. Also used as dental/orthopedic implant hardfacing.
Chemical composition comparison (wt%)
Side-by-side: Stellite 21 (AMS 5895) vs ASTM (AMS 5895)
| Element | Stellite 21 (AMS 5895) | ASTM | Overlap |
|---|---|---|---|
| C | — | ≤ 0.35% | — |
| Si | — | ≤ 1.5% | — |
Mechanical properties
Related materials
Stellite 6
R30006The world's most widely used cobalt-based wear-resistant alloy. CoCrW matrix with hard chromium carbides (M7C3) provides exceptional resistance to abrasion, erosion, cavitation, galling, and corrosion across a wide temperature range. Retains hardness up to 500°C. Non-magnetic. Industry standard for general-purpose wear resistance — suitable for hardfacing (PTA, laser, TIG), casting, and powder metallurgy. Used for valve seats, pump sleeves, bearing surfaces, cutting tools, hot-forming dies, and turbine blade erosion shields.
CoCrMo F75
R30075Cobalt-28Chromium-6Molybdenum investment casting alloy for surgical implants. The standard material for orthopedic hip and knee joint replacements since the 1970s. Excellent biocompatibility, wear resistance (metal-on-metal bearings), and corrosion resistance from passive Cr oxide layer. Also used in dental prosthetics (crowns, bridges, denture frameworks). Typically produced by lost-wax (investment) casting, often followed by HIP to eliminate porosity. ISO designation: ISO 5832-4.
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