Cobalt-Based Alloys
Engineered for Extremes
High-performance cobalt-chromium-tungsten alloy systems designed to deliver superior resistance to wear, corrosion, erosion, and elevated temperatures in the most demanding industrial environments.
Key Performance Characteristics
Multi-dimensional material advantages for critical industrial applications
Exceptional Wear Resistance
Hard carbide phases within a tough matrix provide outstanding resistance to abrasive and adhesive wear. Hardness range: 25-65 HRC.
Superior Corrosion Resistance
Excellent resistance to oxidizing and reducing acids, alkaline solutions, and saltwater environments due to high chromium content and stable passive film.
High-Temperature Stability
Maintains mechanical properties and hardness at elevated temperatures up to 800°C (1472°F). Minimal thermal expansion and excellent thermal shock resistance.
Erosion & Impact Resistance
Resists particle erosion and fluid impingement damage. Suitable for high-velocity slurries, abrasive fluids, and cavitation conditions.
Non-Magnetic Properties
Selected grades maintain non-magnetic characteristics, critical for instrumentation and specialized applications.
Galling Resistance
Low friction coefficient and anti-seizing properties prevent metal-to-metal galling under high contact pressure.
Weldability & Machining
Can be applied via welding overlay, PTA, or HVOF. Machinable using appropriate tooling and techniques.
SYTOP Cobalt Alloy Grade Specifications
Comprehensive material composition and mechanical property data for engineering selection
| Grade | Co % | Cr % | W % | C % | Ni % | Fe % | Hardness (HRC) | Typical Applications |
|---|---|---|---|---|---|---|---|---|
| ST1 | Bal. | 29-32 | 4.0-6.0 | 2.3-2.7 | ≤3.0 | ≤3.0 | 45-55 | Valve seats, sealing surfaces, moderate wear |
| ST3 | Bal. | 27-32 | 7.5-9.5 | 1.8-2.4 | ≤3.0 | ≤3.0 | 42-52 | High-temp applications, chemical equipment |
| ST4 | Bal. | 29-32 | 7.5-9.5 | 1.0-1.4 | ≤3.0 | ≤3.0 | 35-45 | Corrosion resistance priority, pump parts |
| ST6 | Bal. | 27-32 | 3.5-5.5 | 0.9-1.4 | ≤3.0 | ≤3.0 | 35-45 | Low-stress wear, sealing rings, biocompatible |
| ST12 | Bal. | 29-32 | 7.5-9.5 | 1.4-1.8 | ≤3.0 | ≤3.0 | 38-48 | Balanced wear-corrosion, general industrial |
| ST19 | Bal. | 29-33 | 13.5-15.5 | 2.3-2.7 | ≤3.0 | ≤3.0 | 50-58 | Heavy-duty wear, oilfield tools, extrusion dies |
| ST20 | Bal. | 31-35 | 16.5-18.5 | 2.3-2.9 | ≤3.0 | ≤3.0 | 53-60 | Extreme abrasion, slurry erosion, harsh wear |
| ST21 | Bal. | 24-28 | 13.5-15.5 | 0.05-0.15 | ≤3.0 | ≤3.0 | 25-35 | Corrosion-critical, non-magnetic, low hardness |
| ST25 | Bal. | 19-21 | 14.5-16.5 | 0.05-0.15 | 9.0-11.0 | ≤3.0 | 25-35 | Aerospace, turbine, high corrosion environments |
Notes: Bal. = Balance; All values are typical ranges. Final properties depend on manufacturing process and heat treatment. Contact engineering for detailed material data sheets and application-specific recommendations.
ST1
45-55 HRCValve seats, sealing surfaces, moderate wear
ST3
42-52 HRCHigh-temp applications, chemical equipment
ST4
35-45 HRCCorrosion resistance priority, pump parts
ST6
35-45 HRCLow-stress wear, sealing rings, biocompatible
ST12
38-48 HRCBalanced wear-corrosion, general industrial
ST19
50-58 HRCHeavy-duty wear, oilfield tools, extrusion dies
ST20
53-60 HRCExtreme abrasion, slurry erosion, harsh wear
ST21
25-35 HRCCorrosion-critical, non-magnetic, low hardness
ST25
25-35 HRCAerospace, turbine, high corrosion environments
Material Performance Comparison
Understanding relative strengths: Cobalt-Based Alloys vs Tungsten Carbide
| Property / Characteristic | Cobalt-Based Alloys (SYTOP ST Series) | Tungsten Carbide (WC-Co) |
|---|---|---|
| Hardness Range | 25-65 HRC (depending on grade) | 85-92 HRA (extremely high) |
| Toughness & Impact Resistance | Excellent - Absorbs shocks, resists fracture | Limited - Brittle, prone to chipping under impact |
| Corrosion Resistance | Superior - High Cr content, passive film protection | Moderate - Cobalt binder can corrode in harsh acids |
| High-Temperature Performance | Excellent - Retains properties up to 800°C | Limited - Oxidation and binder softening above 500°C |
| Thermal Shock Resistance | Good - Tolerates rapid temperature cycling | Poor - Prone to cracking from thermal cycling |
| Weldability & Repairability | Excellent - Overlay welding, PTA, HVOF possible | Difficult - Requires brazing or replacement |
| Machinability | Moderate - Requires proper tooling and techniques | Very Difficult - Grinding or EDM primarily |
| Abrasive Wear Resistance | Excellent (grades ST19, ST20 approach carbide) | Outstanding - Hardest material option |
| Cost-Effectiveness | Moderate initial cost, excellent lifecycle value | High initial cost, limited repairability |
| Ideal Applications | Valves, seals, pump parts, high-temp/corrosion environments, impact-prone parts, weld overlays | Cutting tools, extreme abrasion (dry conditions), wear inserts, non-corrosive dry abrasion |
Selection Recommendation:
Choose cobalt-based alloys when toughness, corrosion resistance, thermal stability, or weldability are critical. Select tungsten carbide when maximum abrasive wear resistance is required in dry, non-impact, non-corrosive environments. For combined challenges (wear + corrosion + impact + high temp), cobalt alloys typically provide superior overall performance and service life.
Need Material Selection Guidance?
Our engineering team can help you select the optimal cobalt alloy grade based on your specific application requirements, operating conditions, and performance targets.