hastelloy c22 vs c276
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When selecting nickel-chromium-molybdenum alloys for chemical or marine applications, two grades are commonly chosen: Hastelloy C22 (UNS N06022) and Hastelloy C276 (UNS N10276). However, their compositions, properties, and optimal application environments differ slightly, making these differences crucial when selecting materials for demanding industrial conditions.
This guide compares C22 and C276 based on composition, corrosion behavior, mechanical properties, and manufacturing feasibility to help buyers make the right choice.
What is Hastelloy C22 material?
Hastelloy C-22 is a nickel-chromium-molybdenum-tungsten alloy that offers excellent protection against pitting, crevice corrosion, and stress corrosion cracking in harsh chemical environments, such as those containing chlorides, sulfuric acid, and phosphoric acid. This makes it a popular choice for applications in chemical processing, pollution control, and pulp and paper.
What is Hastelloy C276 material?
Hastelloy C276 is a nickel-molybdenum-chromium alloy (designated as UNS N10276 / JIS NW 0276) renowned for its exceptional corrosion resistance in both strongly oxidizing and reducing media. It excels in chloride-rich environments, acidic solutions, and high-temperature oxidizing atmospheres, making it ideal for demanding industrial applications such as chemical processing, pollution control, and flue gas desulfurization systems where resistance to pitting, crevice corrosion, and stress corrosion cracking is critical.
Chemical Composition
| Element | Hastelloy C22 (UNS N06022) | Hastelloy C276 (UNS N10276) |
|---|---|---|
| Nickel (Ni) | Balance | Balance |
| Chromium (Cr) | 20.0 – 22.5% | 14.5 – 16.5% |
| Molybdenum (Mo) | 12.5 – 14.5% | 15.0 – 17.0% |
| Tungsten (W) | 2.5 – 3.5% | 3.0 – 4.5% |
| Iron (Fe) | 2.0 – 6.0% | 4.0 – 7.0% |
| Cobalt (Co) | ≤ 2.5% | ≤ 2.5% |
| Carbon (C) | ≤ 0.015% | ≤ 0.01% |
Mechanical Properties
| Property | Hastelloy C22 | Hastelloy C276 |
|---|---|---|
| Density | 8.69 g/cm³ | 8.89 g/cm³ |
| Tensile Strength (MPa) | 760 | 785 |
| Yield Strength (0.2% MPa) | 350 | 355 |
| Elongation (%) | 55 | 60 |
| Hardness (HRB) | ≤ 95 | ≤ 95 |
Both alloys show excellent ductility and mechanical stability even under high temperatures (up to 1100°C).
Corrosion Resistance Comparison
Hastelloy C276 performs well in oxidizing environments (such as those containing nitric acid and chlorine), offering superior resistance to pitting, crevice corrosion, and stress corrosion cracking. Hastelloy C22, on the other hand, performs well in reducing environments (such as hydrochloric and sulfuric acids).
High-Temperature Performance
Hastelloy C276 slightly outperforms Hastelloy C22 in terms of high-temperature performance. Hastelloy C276 can withstand temperatures up to 1900°F (1037°C), while Hastelloy C22 can withstand temperatures up to 1250°F (676°C). Higher thermal stability and resistance to grain boundary precipitation make Hastelloy C276 a better choice for high-temperature applications.
Common Forms and Standards
| Product Form | Standard |
|---|---|
| Plate / Sheet | ASTM B575 |
| Pipe / Tube | ASTM B622 / B619 |
| Bar / Rod | ASTM B574 |
| Fitting / Flange | ASTM B366 |
| Wire | ASTM B622 |
Both grades are available in seamless and welded forms, suitable for chemical process equipment, flue gas scrubbers, pollution control systems, and heat exchangers.
Manufacturing Process & Availability
Manufacturing Methods:
Hot Extrusion: for thick-wall seamless pipes (wall thickness ≥ 20mm)
Cold Drawing: for precision thin-wall tubing
Forging & Rolling: for plates and bars
Typical Dimensions:
Pipe OD: 6 mm – 219 mm
Wall Thickness: 1 mm – 22 mm
Plate Thickness: 2 mm – 50 mm
Minimum Order Quantity (MOQ): generally 300–500 kg depending on size and form
FAQ
Q: Is Hastelloy C22 better than C276?
A: Not always. C22 performs better in oxidizing environments, while C276 is more effective in reducing environments. The choice depends on the process media.
Q: Can C22 and C276 be welded together?
A: Yes, both alloys are weldable using GTAW or GMAW processes with proper filler metals such as ERNiCrMo-10.
Q: What is the price difference between C22 and C276?
A: C22 is typically 5–10% more expensive due to its higher chromium content and corrosion resistance range.
