Cobalt-Chrome Alloy Stellite 20
Stellite 20 is a high-carbon cobalt-chromium-tungsten hardfacing alloy with its carbide fraction set for severe abrasion and erosion rather than impact.
Reference datasheet — Stellite 20 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AS-CAST condition
Stellite 20 tempers and conditions
Stellite 20 is supplied in 3 conditions, soft to hard. AS-CAST is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As-Deposited | Choose for hand-applied hardfacing of valve seats and tool edges where a thin, low-dilution layer of maximum hardness is wanted. | 420 | 450 | 0.5 | 53 HRC | 1.8 % IACS |
AS-CASTDefault cast hardfacing rod / cast part | Standard supply form: chill-cast bare rod for oxy-acetylene or GTAW hardfacing, and small cast wear parts. | 450 | 480 | 0.5 | 55 HRC | 1.8 % IACS |
PTA / Plasma Transferred Arc powder overlay | Choose for automated, thick (2–6 mm), metallurgically bonded overlays on valve seats, pump sleeves and drilling tools. | 450 | 480 | 0.5 | 54 HRC | 1.8 % IACS |
Supply forms, finishes and certifications
Ways Stellite 20 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
SPRAY-FUSE | Spray-and-Fuse coating | Surface finish |
HVOF | HVOF thermal-spray coating | Coating |
What is Stellite 20?
Stellite 20 is a high-carbon cobalt-chromium-tungsten hardfacing alloy with its carbide fraction set for severe abrasion and erosion rather than impact. It is used as castings, oxy-acetylene and PTA overlays, spray-fuse deposits and HVOF coatings on sealing and sliding faces. Hardness is about 55 HRC with 480 MPa tensile strength and 0.5 % elongation, service is limited to 750 °C, and the deposit is effectively unmachinable except by grinding. Stellite 6 gives more toughness at lower hardness. Stellite 20 has a density of 8.98 g/cm³ (0.324 lb/in³), heavier than 91% of cobalt-chrome alloy grades. It melts at 1,150°C (2,102 °F). Stellite 20 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 96% of cobalt-chrome alloy grades. Elongation at break is 0.5% and the elastic modulus is 250 GPa (36.3 Msi).
What is Stellite 20 used for?
- valve trim
- abrasive wear plates
- oilfield tool hardfacing
Limitations
- Low strength — 450 MPa (65.3 ksi), worse than 96% of cobalt-chrome alloy grades
- Limited ductility — 0.5%, worse than 89% of cobalt-chrome alloy grades
- Low fracture toughness — 12 MPa·√m (10.9 ksi·√in), worse than 89% of cobalt-chrome alloy grades
- Needs corrosion protection — 65/100, worse than 86% of cobalt-chrome alloy grades
- High embodied carbon — 16 kg CO₂/kg, worse than 84% of cobalt-chrome alloy grades
Stellite 20 properties
Typical room-temperature values for Stellite 20-AS-CAST; bars are the position among cobalt-chrome alloy grades.
Physical3
Stellite 20 has a density of 8.98 g/cm³ (0.324 lb/in³), heavier than 91% of cobalt-chrome alloy grades. It melts at 1,150°C (2,102 °F).
Mechanical15
Stellite 20 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 96% of cobalt-chrome alloy grades. Elongation at break is 0.5% and the elastic modulus is 250 GPa (36.3 Msi).
Thermal5
Stellite 20 is rated for continuous service to 750°C (1,382 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), better than 64% of cobalt-chrome alloy grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical3
Stellite 20 conducts electricity at 1.8 % IACS, worse than 75% of cobalt-chrome alloy grades.
Chemical & Environmental2
Corrosion resistance is good (65/100), worse than 86% of cobalt-chrome alloy grades.
Sustainability3
Producing a kilogram of Stellite 20 takes about 200 MJ of energy and emits 16 kg of CO₂ — more than 75% of cobalt-chrome alloy grades. Typical recycled content is 20%.
Manufacturability8
Stellite 20's machinability is not recommended (4/100, worse than 95% of cobalt-chrome alloy grades); weldability poor (25/100); formability not recommended (2/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the cobalt-chrome alloy family
Yield strength against density for every cobalt-chrome alloy grade FabDigit runs. Stellite 20 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Stellite 20
Is Stellite 20 easy to machine?
Effectively unmachinable by conventional cutting — finish by wet grinding with SiC/CBN wheels, EDM or lapping; allow grinding stock on overlays.
Can Stellite 20 be welded?
Deposit by OFW/GTAW with cast rod or by PTA/laser with powder; preheat 400–650 °C, keep interpass hot, slow furnace cool — some check-cracking is normal and usually acceptable in wear service.
Can Stellite 20 be formed, bent or molded?
No cold or hot forming possible; parts are cast to shape or produced as weld overlays/coatings.
Stellite 20 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Crforms M7C3 carbides + solid-solution corrosion resistance | 31 – 34 | 33 |
| WM6C carbide former, hot hardness | 16 – 19 | 17.5 |
| Chigh carbide volume fraction | 2.3 – 2.7 | 2.45 |
| Ni | ≤ 3 | 2.5 |
| Fe | ≤ 3 | 2.5 |
| Si | ≤ 1.5 | 1 |
| Mn | ≤ 1 | 0.5 |
| Mo | ≤ 1 | 0.3 |
| Cobalance, ~38–42 % | balance |
What surface finishes work on Stellite 20?
Grind and lap for sealing faces (Ra <0.4 µm achievable); no plating or anodizing needed — the alloy itself is the wear/corrosion surface.
How much does Stellite 20 cost?
Stellite 20 is a high-cost cobalt-chrome alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Stellite 20 — frequently asked
What is Stellite 20 used for?
Stellite 20 is typically used for valve trim, abrasive wear plates and oilfield tool hardfacing. In short: severe abrasion hardfacing; erosion-resistant overlay grade; low toughness, grind-finished.
What is the yield strength of Stellite 20?
Stellite 20 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 96% of cobalt-chrome alloy grades. Strength varies by condition: see the 3 listed tempers.
Is Stellite 20 easy to machine?
Not especially — machinability is rated not recommended (4/100, worse than 95% of cobalt-chrome alloy grades). Effectively unmachinable by conventional cutting — finish by wet grinding with SiC/CBN wheels, EDM or lapping; allow grinding stock on overlays.
Can Stellite 20 be welded?
Not readily — weldability is rated poor (25/100). Deposit by OFW/GTAW with cast rod or by PTA/laser with powder; preheat 400–650 °C, keep interpass hot, slow furnace cool — some check-cracking is normal and usually acceptable in wear service.
What surface finishes work on Stellite 20?
Grind and lap for sealing faces (Ra <0.4 µm achievable); no plating or anodizing needed — the alloy itself is the wear/corrosion surface.
Can Stellite 20 be formed, bent or molded?
No cold or hot forming possible; parts are cast to shape or produced as weld overlays/coatings.
What is the maximum service temperature of Stellite 20?
Stellite 20 is rated for continuous use to about 750°C (1,382 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Stellite 20 AS-CAST and Stellite 20 OAW-DEP?
AS-CAST is the default condition — standard supply form: chill-cast bare rod for oxy-acetylene or GTAW hardfacing, and small cast wear parts. OAW-DEP: choose for hand-applied hardfacing of valve seats and tool edges where a thin, low-dilution layer of maximum hardness is wanted. Yield strength is 450 MPa in AS-CAST versus 420 MPa in OAW-DEP.
How much does Stellite 20 cost?
Stellite 20 is a high-cost cobalt-chrome alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Stellite 20 alloy data sheet — Kennametal Stellite (2020)
- Cobalt-base hardfacing alloys — properties and application guide — Deloro Wear Solutions (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Cobalt wear alloys) — ASM International (1990)
- AWS A5.21 / A5.13 — Bare and covered hardfacing electrodes and rods (CoCr class) — AWS (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.