Products Features
Extremely High Hardness and Wear Resistance
Stellite 20 achieves a large quantity of hard M₇C₃ and M₆C carbides (with hardness up to 1500-1800 HV) through its \"high carbon, high chromium, high tungsten\" composition design, which are uniformly distributed in the cobalt-based solid solution matrix. Typical hardness in cast or weld-deposited condition is HRC 50-58 (approximately HV 550-700). Its ability to resist abrasive and erosive wear ranks among the best in cobalt-based alloys, making it suitable for high-stress sliding friction and low-angle erosion conditions involving hard particles.
Excellent High-Temperature Hot Hardness and Oxidation Resistance
Stellite 20 retains approximately 40 HRC hardness at 600°C, about 32 HRC at 760°C (1400°F), and around 25 HRC at 870°C (1600°F). The high chromium content promotes the formation of a dense Cr₂O₃ oxide film on the surface. After exposure to air at 800°C for 1000 hours, the oxidation weight gain is less than 1 mg/cm². Its oxidation resistance far exceeds that of tool steels and iron-based wear-resistant materials, making it suitable for high-temperature applications such as hot shearing, hot extrusion, and gas turbines.
Good Corrosion Resistance
With approximately 30% chromium content, Stellite 20 exhibits good corrosion resistance in oxidizing acids (e.g., nitric acid), moderately concentrated non-oxidizing acids (e.g., ≤50% sulfuric acid), and alkaline solutions. In seawater and chloride environments, it primarily undergoes pitting corrosion rather than uniform corrosion, and maintains stable corrosion resistance in high-temperature atmospheres containing sulfur and chlorine.
Machining and Processing Characteristics
As a brittle wear-resistant material, Stellite 20 has a room-temperature tensile strength of approximately 650-850 MPa, a fracture elongation of only 1-2%, and low impact toughness (Charpy V-notch <10 J). Therefore, it is not suitable for applications subjected to severe impact loads but performs excellently in sliding wear and fretting wear conditions. The alloy is typically manufactured by precision casting or powder metallurgy. Common application methods include welding (PTA, TIG, oxy-acetylene). Due to its high susceptibility to hot cracking, preheating to 400-600°C and control of interpass temperature are required during welding, followed by slow cooling after welding. Due to its extremely high hardness, grinding or electrical discharge machining (EDM) is recommended for finishing.
Technical Specifications
Chemical Composition
|
Element |
Standard Requirements |
Notes |
|
Co |
Remaining quantity |
Matrix elements that provide high-temperature strength, thermal stability, toughness, and inherent corrosion resistance |
|
Cr |
30.0 - 34.0% |
Form a dense Cr₂O₃ protective film, providing oxidation and corrosion resistance, and is also a main component of hard carbides |
|
W |
14.0 - 18.0% |
Provide solid solution strengthening, form hard and wear-resistant carbides with carbon, significantly enhancing high-temperature hardness and creep resistance |
|
C |
2.0 - 2.8% |
Forming a large amount of high-hardness carbides (M₇C₃, M₆C) with chromium and tungsten, which is the core source of ultra-high wear resistance |
|
Fe |
≤ 3.0% |
Strict control to ensure purity and microstructural stability |
|
Ni |
≤ 3.0% |
Strictly control to prevent excessive nickel from causing embrittlement |
|
Si |
≤ 2.0% |
Deoxidizer |
|
Mn |
≤ 1.0% |
Deoxidizer, improve processing performance |
|
Mo |
≤ 1.0% |
Optional small additions to provide enhanced solid solution strengthening and pitting corrosion resistance |
Physical Properties
|
Property |
Value/Range |
Test Conditions |
|
Density |
8.69 - 8.87 g/cm³ |
Room temperature (20°C) |
|
Melting Point |
1240 - 1350°C |
- |
|
Coefficient of Thermal Expansion (20-100°C) |
11.5 - 12.5 × 10⁻⁶ /K |
- |
|
Elastic modulus (Young's modulus) |
205 - 230 GPa |
Room temperature |
|
Thermal conductivity (20°C) |
14.5 - 14.8 W/(m·K) |
- |
|
Resistivity |
0.85 - 0.94 μΩ·m |
- |
|
Magnetism |
Non-magnetic (weakly magnetic) |
Cobalt-based alloys are typically non-magnetic or weakly magnetic at room temperature |
Mechanical Properties (Cast/Welded Condition, Typical Values)
|
Property |
Typical Value |
Specification |
|
Hardness (Cast/Weld Overlay Condition) |
50 - 58 HRC(550 - 700 HV) |
AWS A5.21 ECoCr-C |
|
Tensile Strength |
650 - 850 MPa |
- |
|
Strength (0.2% Offset) |
550 - 700 MPa |
- |
|
Elongation |
1 - 2% (brittle material) |
- |
|
Compressive strength at room temperature |
2000 - 2500 MPa |
- |
|
Impact toughness |
Charpy V-notch impact energy < 10 J |
- |
Note: Stellite 20 is a brittle wear-resistant material. Its main performance indicators are hardness and wear resistance. It has low tensile strength and extremely poor plasticity, and is generally not recommended for structural components subjected to high tensile loads.
High-temperature performance
Stellite 20 exhibits exceptional ability to maintain hardness at high temperatures. Below are typical reference values for hardness variation with temperature:
|
Temperature |
Typical hardness |
|
Room Temperature |
50 - 58 HRC |
|
400°C(750°F) |
46 HRC |
|
600°C(1110°F) |
40 HRC |
|
760°C(1400°F) |
32 HRC |
|
870°C(1600°F) |
25 HRC |
Antioxidant Performance:
In high-temperature oxidation environments, Stellite 20 forms a dense Cr₂O₃ oxide film on its surface. After exposure to air at 800°C for 1000 hours, the oxidation weight gain is less than 1 mg/cm², demonstrating better antioxidant properties than most iron-based heat-resistant steels.
Long-Term Thermal Stability:
When in service at temperatures above 600°C for extended periods, the alloy exhibits excellent microstructural stability with no significant phase transformation or softening. The allotropic transformation of the cobalt matrix and solid-solution strengthening from tungsten collectively ensure its long service life under high-temperature conditions.
Applicable Media:
1. Seawater and saltwater (excellent pitting corrosion resistance; primarily susceptible to pitting rather than uniform corrosion)
2. Oxidizing acids: Nitric acid (excellent corrosion resistance at room temperature)
3. Non-oxidizing acids: Sulfuric acid (concentration ≤50%), hydrochloric acid (concentration ≤30%) (corrosion rate typically <0.1 mm/a)
4. Alkaline solutions: Sodium hydroxide, potassium hydroxide (resistant to all concentrations)
5. Organic acids: Acetic acid, formic acid, etc.
6. High-temperature oxidizing atmospheres and sulfur/chlorine-containing gases (a protective Cr₂O₃ film forms on the surface)
Note: Stellite 20 has limited corrosion resistance in strongly reducing acids (e.g., concentrated hot hydrochloric acid) and fluorine-containing media. For high-stress friction conditions, it is recommended to use in conjunction with lubricants.
Stellite 20 is designed for demanding applications requiring extremely high wear resistance and high-temperature hardness, recommended for the following fields:
Application Fields
-
Valves and Sealing Industry: High-pressure/super-high-pressure valve sealing surfaces (seats, discs, stems), pump casings, rotating seals, mechanical seals, where its exceptional hardness and wear resistance are suitable for high-pressure differential media containing hard particles.
-
Aerospace and Energy: Gas turbine seals, blade wear strips, combustion chamber components, engine valve sealing surfaces, turbocharger seals, leveraging its ability to maintain high hardness and excellent wear resistance at temperatures above 760°C.
-
Oil and Gas: Downhole tool wear parts, drill pipe joints, valve internals, mud pump components, resisting high-speed erosion and abrasive wear from sand and particulate-laden media.
-
Industrial Machinery and Tools: Hot extrusion dies, hot shear blades, die-casting molds (gates, plungers), extruder screws, cutting edges for plastic processing, centerless grinding machine supports.
-
Chemical and Petrochemical: Reactor agitator blades, wear-resistant linings for heat exchanger tube plates, pump and valve sealing surfaces, withstanding the combined effects of corrosion and wear.
-
Nuclear Power Industry: Nuclear island valve seals, nuclear-grade wear-resistant liners, utilizing its high radiation tolerance and microstructural stability.
-
Shipbuilding and Offshore Engineering: Wear surfaces of propeller shafts, pump and valve components, resisting seawater corrosion and mechanical wear.
-
Automotive and Internal Combustion Engines: High-performance exhaust valves, rocker arms, turbocharger seals, maintaining wear and seizure resistance at high temperatures.
-
Steel and Heat Treatment: Hot shear blades, hot saw blades, furnace bottom rolls, guide rolls, withstanding high-temperature oxidation and abrasive wear.
-
Glass and Ceramic Forming: Glass molds, hot extrusion dies, due to their good corrosion resistance to molten glass and ceramics.
Delivery and Customization
We offer flexible and reliable supply chain solutions to ensure you receive Stellite 20 materials that perfectly match your project requirements.
|
Form |
 Sheet/Plate
|
 Bar/Rod
|
 Seamless Pipe
|
 Strip/Sheet Coil
|
 Wire/Wire Rod
|
|---|---|---|---|---|---|
|
Conventional Range |
Thickness: 0.5 - 100 mm |
Diameter Φ6-500mm |
Outer diameter Φ10-300mm |
Thickness: 0.1 – 3.0 mm |
Diameter Φ0.5-10mm |
|
Customization Capability |
Special thick/thin rolling, ultra-wide plates; special surface treatment, fixed-length cutting |
Large-sized forged bars (up to Φ800 mm), special-shaped bars, and various heat treatment conditions |
Large-diameter thick-walled pipes, special alloy composition; Pipe end processing (beveling, fixed length) |
Different hardness conditions, special heat treatments (stabilization treatment, grain size control), acid-washed surfaces, electrolytic polishing, coatings, or special protective films |
Special surface treatment, precision drawing |
Why Choose Us? - Reliable Engineering Technology. Dependable Delivery.
We are not just a supplier, but a trusted materials partner for you in China.
Vertically Integrated Production
Own 20,000㎡ facility with 10+ automated lines (8,000+ tons/year). In-house tooling & die center enables rapid customization and effective cost control - no middleman markup.
Strict Quality Control at Every Stage
Full traceability across key QC checkpoints throughout production. 100% compliant with ASTM/ASME, EN, and GB standards. Material test reports available with every shipment.
Reliable Delivery & Export Packaging
10+ years exporting to Europe, North America, Southeast Asia & Middle East with waterproof and anti-rust protection, combined with flexible shipping options ensures safe and on-time arrival.
Sample Validation Before Mass Production
We provide free samples for quality verification, allowing you to place bulk orders only after approval. We ensure consistency from sample to mass production by accurate dimensional measurement and transparent manufacturing.
FAQ
Q: What are the main advantages of Stellite 20?
Q: What heat treatment is required for Stellite 20?
Q: What is the maximum service temperature?
Q: What is the difference between Stellite 20 and Stellite 6?
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