Stellite 21 Alloy

Stellite 21 consists of a CoCrMo alloy matrix containing dispersed hard carbides which strengthen the alloy and increase its hardness but also decrease the ductility. The type, shape, size and distribution of the carbides is strongly influenced by the processing history of the alloy, and for this reason the mechanical properties of Stellite 21 are very dependent upon the manufacturing route and any subsequent heat treatments.

Stellite 21 has excellent resistance to thermal and mechanical shock. Optimum high-temperature strength is obtained by solution heat treatments at 1200–1240C (2190–2265F) followed by quenching and aging in the temperature range 700–1150C (1290–2100F).

Nominal Composition
Base: Co
Cr: 26-29
Mo: 4.5-6.0
C: <0.35
Ni: <3.0
Others: Fe, Si, Mn

Hardness HRC: 27-40 (Can work harden up to 48)

Typical UTS: 710 MPa

UNS: R30021, W73041, W73021

AMS: 5385, 5819