Products Features
Excellent Hardness and Wear Resistance
Stellite 6 forms M₇C₃-type carbides uniformly distributed within the cobalt-based solid solution matrix. Its typical hardness ranges from HRC 35-45 (approximately HV 380-450) in cast or overlay-welded conditions. Compared to high-carbon grades (e.g., Stellite 1, 4), it offers moderate hardness with superior toughness, effectively resisting abrasive, adhesive, and erosive wear. It is particularly suitable for sliding friction conditions subjected to moderate impact.
Good High-Temperature Red Hardness and Oxidation Resistance
Stellite 6 retains approximately 30 HRC hardness at 600°C and about 25 HRC up to 760°C (1400°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, far exceeding the oxidation resistance of ordinary tool steels and iron-based wear-resistant alloys. This makes it ideal for continuous high-temperature applications such as hot working tools and high-temperature valves.
Superior Corrosion Resistance
With approximately 30% chromium content, Stellite 6 demonstrates 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 exhibits pitting corrosion rather than uniform corrosion. Its corrosion resistance in high-temperature atmospheres containing sulfur and chlorine is particularly notable, making it an ideal choice for applications where corrosion and wear coexist, such as chemical processing, petrochemicals, and flue gas desulfurization.
Excellent Machinability and Weldability
Stellite 6 is one of the most machinable and weldable grades among cobalt-based alloys. It can be hardfaced using various overlay welding processes such as PTA (Plasma Transferred Arc), TIG, MIG, and oxy-acetylene welding. Its susceptibility to hot cracking is significantly lower than high-carbon grades. Preheating to 300-500°C and slow cooling after welding are typically sufficient. Limited machining is possible in the annealed condition, with final finishing recommended via grinding or Electrical Discharge Machining (EDM).
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 |
27.0 - 31.0% |
Form a dense Cr₂O₃ protective film, providing oxidation and corrosion resistance, and is also a main component of hard carbides |
|
W |
4.0 - 6.0% |
Provide solid solution strengthening, form hard and wear-resistant carbides with carbon, thereby enhancing high-temperature hardness and creep resistance. |
|
C |
0.9 - 1.4% |
Forming appropriate carbides with chromium and tungsten to provide wear resistance while maintaining good toughness |
|
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 |
1280 - 1400°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(20°C) |
0.85 - 0.94 μΩ·m |
Room temperature |
|
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) |
35 - 45 HRC(380 - 450 HV) |
AWS A5.21 ECoCr-A |
|
Tensile Strength |
750 - 900 MPa |
- |
|
Yield Strength (0.2% Offset) |
600 - 700 MPa |
- |
|
Elongation |
1 - 3% (brittle material) |
- |
|
Compressive strength at room temperature |
2000 - 2300 MPa |
- |
|
Impact toughness |
Charpy V-notch 10 - 20 J |
- |
High-temperature performance
High-Temperature Hardness (Core Advantage): Stellite 6 maintains good hardness at high temperatures. Below are typical reference values for how hardness changes with temperature:
|
Temperature |
Typical hardness |
|
Room Temperature |
35 - 45 HRC |
|
400°C(750°F) |
32 HRC |
|
600°C(1110°F) |
30 HRC |
|
760°C(1400°F) |
25 HRC |
|
870°C(1600°F) |
20 HRC |
Antioxidant Performance:
In high-temperature oxidation environments, Stellite 6 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, 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, saltwater (excellent pitting corrosion resistance)
2. Oxidizing acids: Nitric acid (superior 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, sulfur/chlorine-containing gases (forms a protective Cr₂O₃ film on the surface)
Note: Stellite 6 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 lubricating media.
Stellite 6 is the most widely used cobalt-based wear-resistant alloy, recommended for the following applications:
Application Fields
-
Valves and Sealing Industry: Sealing surfaces of various control valves, ball valves, and gate valves (valve seats, valve discs, valve stems), pump casings, mechanical seal rings, and rotating seal rings, utilizing its excellent wear resistance, corrosion resistance, and thermal shock resistance.
-
Aerospace and Energy: Gas turbine blades, combustion chamber components, engine valve sealing surfaces, and turbocharger seal rings, maintaining good mechanical properties at temperatures up to 760°C.
-
Oil and Gas: Wear parts of downhole tools, drill pipe joints, valve internals, and pump shaft wear sleeves, resisting high-speed erosion and wear from sand-laden media.
-
Industrial Machinery and Tools: Hot shear blades, hot forging dies, die-casting dies (gates, plungers), extruder screws, centerless grinding machine supports, screw presses, and cutting edges for plastic processing.
-
Chemical and Petrochemical: Reactor agitator blades, wear-resistant linings for heat exchanger tube plates, and pump/valve sealing surfaces, withstanding the combined effects of corrosion and wear.
-
Nuclear Power Industry: Nuclear island valve seals and nuclear-grade wear-resistant liners, leveraging its high radiation tolerance and microstructural stability.
-
Shipbuilding and Offshore Engineering: Wear-resistant surfaces of propeller shafts and pump/valve components, resisting seawater corrosion and mechanical wear.
-
Automotive and Internal Combustion Engines: High-performance engine exhaust valves, rocker arms, and turbocharger seal rings, maintaining wear and seizure resistance at high temperatures.
-
Steel and Heat Treatment: Hot shear blades, hot saw blades, furnace bottom rolls, and guide rolls, withstanding high-temperature oxidation and abrasive wear.
-
Glass and Ceramic Forming: Glass molds and hot extrusion dies, due to their excellent corrosion resistance to molten glass and ceramics.
Delivery and Customization
We offer flexible and reliable supply chain solutions to ensure you receive Stellite 6 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 6?
Q: What heat treatment is required for Stellite 6?
Q: What is the maximum service temperature?
Q: What is the difference between Stellite 6 and Stellite 4?
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