Filler Metals


STELLITE 21 STELLITE 21




Nominal Composition (mass %) and Physical Properties

Co Cr Mo C Others Hardness** Density Melting Range
Base 26-29 4.5-6.0

0.20-0.35

Ni,Fe,Si,

Mn,Mo

27-40 HRC**

290-430 HV**

8.33 g/cm3

0.301 lb/in3

2360-2615 ํ F

1295-1435 ํ C

**Higher values indicate a typical work hardened surface. Stellite® 21 can work harden up to 550hv (48HRC).

 

Stellite® 21 (previously known as Stellite® 8) was developed in the mid 1930s as a corrosion resistant CoCr alloy,

and rapidly found application as a biocompatible hip implant and denture alloy. Many of the alloys currently used

in medical applications are variants of the original Stellte® 21 composition. It was also one of the first heat-resistant

alloys trialled for ues in jet engines.

Stellite® 21 consists of a CoCrMo alloy matrix containing dispersed hard carbides which stengthen 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 heatments.

Dueto the low volume fraction of carbides, the Co-based alloy martrix dominates the wear and corrosion properties.

Stellite® 21 has excellent cavitation, qalling and metal-tometal sliding wear resistance, but is not recommended for severe

hard particle abrasion. The surface can work harden considerbly during wear or even during, and the use of correct 

machining  tools and techniques is important to achieve optimal results.

Stellite® 21 has excellent resistance to thermal and mechanical shock. Optimum high temperature strength is obtained

by solution heat treatment at 1200-1240 ํC (2190-2265 ํ F) followed by quenching, and aging in the temperature

range 700-1150 ํ F).

Stellite® 21 can be cast, powder metallurgically processed, or applied as a weld hardfacing. It is recommended for applications

involving cavitation,erosion, corrosion and/or high temperatures, such as valve trim for petrochemical and power

genneration. Due to its good impact resistance, it has been widly used in the building up of forging or hot stamping dies.

The oxyacetylene weld deposition method is not recommended for this alloy.

Corrosion Resistance

Stellite® 21 is resistant to oxidizing and reducing gaseous atmospheres up to 1150 ํC (2100 ํ F). Because its ternary alloying 

element is Mo and not W, it has higher resistance to reducing or complex environments (e.g. sulphuric acid,hydrochloric acid,

and sour gas) than CoCrW alloys such as Stellite® 6. The typical electrode potential in sea water at room temperature is approx.-0.3 V

(SCE). Like stainless steels, Stellite® 21 corrodes primarily by a pitting mechanism and not by general mass loss in seawater 

and chloride solutions. More information regarding corrosion resistance can be provided on request.

 

Nominal Thermal Expansion Coefficient (from 20 ํC/68 ํ F to stated temperature)

 

100 ํ C

(212 ํ F)

200 ํ C

(392 ํ F)

300 ํC

(572 ํF)

400 ํ C

(752 ํ F)

500 ํ C

(932 ํ F)

600 ํ C

(1112 ํ F)

700 ํ C

(1292 ํ F)

800 ํ C

(1472 ํ F)

900 ํ C

(1652 ํF)

um/m.k 11.0 11.2 12.0 12.65 13.1 13.6 14.3 14.7 15.21
u-inch/inch- ํF 6.1 6.2 6.7 6.7 7.3 7.6 7.9 8.2 8.45

 

Nominal Tensile Properties at Room Temperature

Note.Th Mechanical properties of Stellite ® 21 are very dependent opon the manufacturing route and heat treatment.

  Utimate Tensile Strength Rm Yield Stress Rp(0.2%) Elongation Elastic Modulus
  ksi MPa ksi MPa A(%) psi GPa

Invesment Castings or

undiluted weld metal

103 710 82 565 9 36.2x10 6 250
Stellite®  HS-21(*) 145 1000 87 650 20 35.5x10 6 245

(*) "HS" = HIP -consolidated from the powder form

Nominal Hot Hardness (DPH) as-cast

20 ํC

(68 ํ F)

100 ํ C

(212 ํ F)

200 ํ C

(392 ํ F)

300 ํC

(572 ํF)

400 ํ C

(752 ํ F)

500 ํ C

(932 ํ F)

600 ํ C

(1112 ํ F)

700 ํ C

(1292 ํ F)

800 ํ C

(1472 ํ F)

900 ํ C

(1652 ํF)

347 279 248 228 208 197 181 153 123 92

 

Thermal and Electrical Properties

  Approximate value at Room Temperature
Thermal conductivity 14.5 W/m.k 100.5 Btu-in/hr/ft2/ ํF
Electrical resistivity 87.38u-ohm.cm 34.4 u-ohm.inch

 

Product Forms and Cross Reference Specifications

Stellite® 21 is avalable as welding wire, rod , power, and electrodes; and finished castings and power-metallurgically produced P/M parts.

Deloro Stellite also offers hardfacing services.

Stellite® 21 can be supplied to the follwing specifications:

SPECIFICATION PRODUCT FORM
UNS R30021 Rod, Castings
UNS W73041 Wire
UNS W73021 Electrode
ams 5385 Castings
AMS 5819 Rod, Wire

 

SPECIFICATION PRODUCT FORM

AWS A5.21 / ASME BPVC IIC SFA 5.21 ERCoCr-C

Rod

AWS A5.21 / ASME BPVC IIC SFA 5.21 ERCCoCr-c

 Wire

AWS A5.13 / ASME BPVC IIC SFA 5.13 ECoCr-C

 Electrode

SAE J467

HIP- Consolidated

Stellite is a registered Trade Name of Deloro Stellite.

 

Deloro Stellite manufactures sophisticated alloys in the form of casting, powders, coatings, consumables, and machined parts

that resist wear, corrosion, and abrasion. Information provided in this document is intended only for general guidance about 

Deloro Stellite products and is the best information in our possession at the time. Product users may request information about

their individual use of our of our products, but Deloro Stellite does not warrant or guarantee this information in any way. Selection

and purchase of Deloro Stellite products is the sole responsibility of the product user based on the suitability of each use. Individual

applications must be fully evaluated by the user, including compliance with applicable laws, requlations, and non-infringement.

Deloro Stellite cannot knowor anticipate the many varibles thet affect individual product use and individual performance results

may vary. For these reasons, Deloro Stellite does not warrant or quarantee advice or information in this document, assumes no liability

regarding the same, and expressly disclaims any warranty of any kind,including any warranty of fitness for a particular pupose,

regarding the same.







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