Hastelloy C22 (UNS N06022) and Hastelloy C276 (UNS N10276) are two of the most widely used nickel-chromium-molybdenum alloys for highly corrosive environments. Both alloys offer exceptional resistance to pitting, crevice corrosion, stress corrosion cracking, and a wide range of aggressive chemicals.
Although they appear similar, their chemical composition, corrosion behavior, mechanical properties, and application focus differ significantly. Selecting the correct alloy can improve equipment reliability, extend service life, and reduce lifecycle costs.
This guide compares Hastelloy C22 and Hastelloy C276 in terms of chemical composition, physical properties, mechanical performance, corrosion resistance, service temperature, applications, and cost.
Quick Comparison
| Propriété | Hastelloy C22 | Hastelloy C276 |
| Numéro UNS | N06022 | N10276 |
| ASTM Standards | ASTM B574, B575, B619, B622, B366 | ASTM B564, B575, B619, B622, B366 |
| Chrome | 20–22.5% | 14.5–16.5% |
| Molybdène | 12.5–14.5% | 15–17% |
| Tungstène | 2.5–3.5% | 3–4.5% |
| Oxidizing Media | ★★★★★ | ★★★★☆ |
| Reducing Media | ★★★★☆ | ★★★★★ |
| Pétrole et gaz | ★★★★☆ | ★★★★★ |
| Traitement chimique | ★★★★★ | ★★★★★ |
Chemical Composition Comparison
| Élément | Hastelloy C22 | Hastelloy C276 |
| Nickel (Ni) | Équilibre | Équilibre |
| Chrome (Cr) | 20.0–22.5% | 14.5–16.5% |
| Molybdène (Mo) | 12.5–14.5% | 15.0–17.0% |
| Tungstène (W) | 2.5–3.5% | 3.0–4.5% |
| Fer (Fe) | 2–6% | 4–7% |
| Cobalt (Co) | ≤2,5% | ≤2,5% |
| Manganèse (Mn) | ≤0,5% | ≤1,0% |
| Silicium (Si) | ≤0,08% | ≤0,08% |
| Carbone (C) | ≤0,015% | ≤0.01% |
| Vanadium (V) | ≤0,35% | ≤0,35% |
| Phosphore (P) | ≤0.02% | ≤0.04% |
| Soufre (S) | ≤0.02% | ≤0,03% |
Composition Analysis
Hastelloy C22
- Higher chromium content
- Better oxidation resistance
- Excellent resistance to wet chlorine and ferric chloride
Hastelloy C276
- Higher molybdenum and tungsten
- Superior reducing acid resistance
- Outstanding localized corrosion resistance
Comparaison des propriétés physiques
| Propriété | C22 | C276 |
| Densité | 8,69 g/cm³ | 8,89 g/cm³ |
| Plage de fusion | 1357–1400°C | 1325–1370°C |
| Chaleur spécifique | 410 J/kg·K | 427 J/kg·K |
| Conductivité thermique | 11.1 W/m·K | 10.2 W/m·K |
| Résistivité électrique | 1.14 μΩ·m | 1.30 μΩ·m |
| Module d'élasticité | 206 GPa | 205 GPa |
| Thermal Expansion (20–100°C) | 12.4 μm/m·°C | 11.2 μm/m·°C |
Physical Property Highlights
- C276 is slightly denser because of its higher Mo and W content.
- C22 has marginally better thermal conductivity.
- Both alloys maintain dimensional stability at elevated temperatures.
Comparaison des propriétés mécaniques
| Propriété | Hastelloy C22 | Hastelloy C276 |
| Résistance à la traction | ≥690 MPa | ≥690 MPa |
| Limite d'élasticité (0,2%) | ≥310 MPa | ≥283 MPa |
| Élongation | ≥45% | ≥40% |
| Dureté | ≤100 HRB | ≤100 HRB |
Mechanical Performance
Both alloys provide:
- Excellent toughness
- High ductility
- Outstanding weldability
- Excellent fatigue resistance
C22 generally exhibits a slightly higher yield strength than C276.
Maximum Service Temperature Comparison
| Propriété | Hastelloy C22 | Hastelloy C276 |
| Maximum Continuous Service Temperature | ≈1040°C (1900°F) | ≈1090°C (2000°F) |
| Short-Term Oxidation Resistance | Excellent | Excellent |
| Thermal Stability | Excellent | Excellent |
Temperature Analysis
Both alloys retain good mechanical properties at elevated temperatures. However:
- Hastelloy C276 is generally preferred for higher-temperature reducing environments because of its higher molybdenum and tungsten content.
- Hastelloy C22 performs exceptionally well in oxidizing atmospheres and mixed chemical environments.
Note: The actual maximum service temperature depends on the operating medium, mechanical load, oxidation conditions, and design code requirements. Continuous service limits should always be verified for the specific application.
Corrosion Resistance Comparison
| Environnement | C22 | C276 |
| Hydrochloric Acid | ★★★★☆ | ★★★★★ |
| Acide sulfurique | ★★★★☆ | ★★★★★ |
| Nitric Acid | ★★★★★ | ★★★★☆ |
| Ferric Chloride | ★★★★★ | ★★★★☆ |
| Wet Chlorine | ★★★★★ | ★★★★☆ |
| Mixed Acids | ★★★★★ | ★★★★★ |
| Seawater | ★★★★★ | ★★★★★ |
| Corrosion par piqûres | Excellent | Excellent |
| Corrosion caverneuse | Excellent | Excellent |
| Fissuration par corrosion sous contrainte | Excellent | Excellent |
Soudabilité
Both Hastelloy C22 and C276 have excellent weldability using GTAW, GMAW, SMAW, and PAW welding processes.
Post-weld heat treatment is generally not required when proper filler metals and welding procedures are used.
Applications typiques
Hastelloy C22
- Chemical reactors
- Pharmaceutical equipment
- Bleaching systems
- Flue Gas Desulfurization (FGD)
- Waste treatment
- Chlorination equipment
Hastelloy C276
- Pétrole et gaz
- Offshore platforms
- Petrochemical plants
- Pressure vessels
- Heat exchangers
- Sour service piping
- Acid processing equipment
Cost Comparison
| Article | Hastelloy C22 | Hastelloy C276 |
| Raw Material Cost | Plus haut | Inférieur |
| Manufacturing Cost | Slightly Higher | Inférieur |
| Market Availability | Modéré | Excellent |
| Global Demand | Moyen | Très élevé |
| Typical Lead Time | Longer | Shorter |
Cost Analysis
Although both alloys belong to the premium nickel alloy family, Hastelloy C22 generally costs 5–15% more than Hastelloy C276, depending on market prices for nickel, chromium, molybdenum, and tungsten.
Reasons include:
- Higher chromium content
- Lower global production volume
- More specialized applications
- Smaller market demand
Hastelloy C276 benefits from larger production volumes and broader industrial use, making it easier to source and often more cost-effective.
Which Alloy Should You Choose?
| Application | Recommended Alloy |
| Hydrochloric Acid | ⭐ C276 |
| Acide sulfurique | ⭐ C276 |
| Nitric Acid | ⭐ C22 |
| Wet Chlorine | ⭐ C22 |
| Ferric Chloride | ⭐ C22 |
| Mixed Acids | ⭐ C22 |
| Pétrole et gaz | ⭐ C276 |
| Offshore | ⭐ C276 |
| Traitement chimique | Both |
Procurement Recommendation
Choose Hastelloy C22 when:
- Excellent resistance to oxidizing chemicals is required.
- The service involves wet chlorine, ferric chloride, or mixed acid environments.
- Maximum corrosion resistance is the primary concern.
Choose Hastelloy C276 when:
- The process involves strong reducing acids such as hydrochloric or sulfuric acid.
- The application is in oil & gas, offshore, or petrochemical industries.
- Lower procurement cost and wider availability are important.
Available Product Forms
SSMALLOYS manufactures and supplies:
- Plaques et feuilles
- Pipes & Tubes
- Raccords de tuyauterie
- Brides
- Raccords forgés
- Bars & Rods
- Pièces forgées
- Fixations
Manufactured according to:
- ASTM B564
- ASTM B575
- ASTM B619
- ASTM B622
- ASTM B366
- ASME SB564
- ASME SB366
- ASME SB622
FAQs About Hastelloy C-22 vs Hastelloy C-276
Not necessarily. C22 performs better in oxidizing environments, while C276 offers superior resistance in reducing acids and remains the preferred choice for many oil & gas applications.
In some cases, yes. However, alloy selection should be based on the service medium, temperature, pressure, corrosion mechanism, and applicable design standards.
Hastelloy C22 is typically 5–15% more expensive than Hastelloy C276 because of its higher chromium content and lower production volume.
Both alloys provide excellent weldability and generally do not require post-weld heat treatment.
Hastelloy C276 is the most widely used nickel alloy in chemical processing, oil & gas, offshore, and power generation due to its versatility and availability.
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