When it comes to extreme corrosion resistance in aggressive chemical environments, Hastelloy C22 and C276 are the top contenders. Both are nickel-chromium-molybdenum alloys, but they have distinct differences in pitting resistance, weldability, and application-specific performance. Choosing the wrong grade can lead to premature failure in chemical processing, oil & gas, or pharmaceutical equipment. Let's settle the debate – data-driven, no marketing fluff.
As a leading nickel alloy manufacturer in Mumbai, Delta Super Alloys supplies Hastelloy C22, C276, Inconel, Monel, and other superalloys in round bars, forged components, and custom shapes. This guide helps you pick the right one.
Quick Overview: C22 vs C276
Hastelloy C276 (UNS N10276) – The industry veteran. Excellent resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC) in harsh reducing environments like wet chlorine, sulfuric acid, and seawater.
Hastelloy C22 (UNS N06022) – The upgraded successor. Offers superior overall corrosion resistance, especially in oxidizing conditions (e.g., ferric chloride, mixed acids). Better weldability and thermal stability than C276.
Detailed Comparison: Chemical Composition
| Element (% max unless specified) | Hastelloy C276 (UNS N10276) | Hastelloy C22 (UNS N06022) |
|---|---|---|
| Nickel (Ni) | Remainder (balance) | Remainder (balance) |
| Chromium (Cr) | 14.5 - 16.5 | 20.0 - 22.5 (higher → better oxidizing acid resistance) |
| Molybdenum (Mo) | 15.0 - 17.0 | 12.5 - 14.5 |
| Iron (Fe) | 4.0 - 7.0 | 2.0 - 6.0 |
| Tungsten (W) | 3.0 - 4.5 | 2.5 - 3.5 |
| Cobalt (Co) | ≤ 2.5 | ≤ 2.5 |
Key difference: C22 has higher chromium (20-22%) vs C276 (14.5-16.5%), giving C22 superior resistance to oxidizing media (like ferric chloride, chlorine dioxide). C276 has slightly higher molybdenum, benefiting reducing acid resistance.
Corrosion Resistance Face-off
| Environment / Media | C276 Performance | C22 Performance | Winner |
|---|---|---|---|
| Wet Chlorine Gas | Excellent | Superior (more Cr) | ✅ C22 |
| Sulfuric Acid (all conc.) | Excellent | Excellent (slightly better in dilute) | Tie |
| Hydrochloric Acid | Very Good | Very Good | Tie |
| Pitting Resistance Equivalent (PRE) | ~65 | ~67 | ✅ C22 (marginal) |
| Stress Corrosion Cracking (SCC) | Excellent | Superior | ✅ C22 |
| Oxidizing acids (HNO3 + HF, FeCl3) | Good | Excellent | ✅ C22 |
| Seawater / Brine | Excellent | Excellent | Tie |
Mechanical Properties & Fabrication
| Property | C276 | C22 |
|---|---|---|
| Tensile Strength (MPa) | 690 min | 690 min |
| Yield Strength (MPa) | 283 min | 310 min |
| Elongation (%) | 40 | 45 |
| Hardness (HRB) | ~87 | ~85 |
| Weldability (without post-weld cracking) | Good (requires low heat input) | Excellent (more stable microstructure) |
Winner for fabrication: C22 – better thermal stability, less susceptible to weld heat-affected zone (HAZ) attack. C276 needs careful welding procedures to avoid carbide precipitation.
Typical Applications: Where to Use Each?
Use C276 For:
- Chemical reactors & vessels
- Flue gas desulfurization (FGD) scrubbers
- Pulp & paper bleaching systems (chlorine dioxide)
- Seawater cooling pipes
- Offshore oil & gas platforms
- Waste treatment plants
Use C22 For:
- Extremely aggressive mixed acids (HCl + HNO3)
- Pharmaceutical & biopharma reactors
- Ferric chloride injection systems
- Nuclear waste processing
- High-temperature oxidizing environments
- Welded fabrications requiring maximum corrosion margin
"If your environment contains both oxidizing and reducing acids (e.g., mixed acid pickling baths), choose Hastelloy C22. For high temperature reducing conditions with chlorides (like FGD systems), C276 is the proven workhorse. C22 costs ~15-20% more, but the extra chromium pays off in severe oxidizing service."
Cost & Availability Comparison
C276: Widely available, slightly lower cost (~₹7,500-9,500/kg for round bar as of 2026). Long history, many suppliers.
C22: Premium grade, ~15-25% costlier than C276. Longer lead times for custom sizes, but worth it for critical oxidizing service.
As a Hastelloy round bar supplier, Delta Super Alloys maintains stock of both grades in diameters from 6mm to 300mm, with mill test certificates and NACE compliance.
No universal winner – it depends on your corrosive cocktail.
→ Pick C276 if: Your media is reducing acids (sulfuric, hydrochloric), seawater, or FGD service. It's the industry standard with proven track record.
→ Pick C22 if: You face mixed acids, oxidizing chlorides (FeCl3, CuCl2), or need maximum weld integrity. Also for pharmaceutical / biotech where corrosion cannot be tolerated.
Pro tip: For new plants designing for longevity, many engineers now upgrade to C22 for the extra corrosion margin – the initial cost premium is often recovered by avoiding unplanned shutdowns.
Why Choose Delta Super Alloys for Hastelloy Round Bars?
- Certified nickel alloy manufacturer in Mumbai – ISO, NACE, ASTM compliant
- Wide stock: C276, C22, Inconel 600/625/718, Monel 400/K500, Alloy 20
- Custom forged components as per drawings (shafts, rings, flanges)
- Third-party testing – PMI, mechanical, corrosion, UT
- Global export experience – Oil & Gas, Chemical, Pharma, Marine clients
As trusted by industry leaders, Delta Super Alloys delivers quality, certification, and on-time delivery for critical applications.