Hastelloy C276 vs C22: Which Corrosion-Resistant Alloy Should You Choose?
Complete comparison of chemical composition, corrosion resistance in aggressive acids, mechanical properties, and industry applications. Choose the right grade for your project.
🔑 Quick Comparison
| Property | Hastelloy C276 (N10276) | Hastelloy C22 (N06022) | 🏆 Winner |
|---|---|---|---|
| Cr Content | 14.5-16.5% | 20-22.5% | ✅ C22 |
| Mo Content | 15-17% | 12.5-14.5% | — |
| W Content | 3-4.5% | 2.5-3.5% | — |
| PREN | ≥ 60 | ≥ 65 | ✅ C22 |
| Oxidizing Acid Resistance | Good | Excellent | ✅ C22 |
| Reducing Acid Resistance | Excellent | Very Good | ✅ C276 |
| Pitting Resistance | Excellent | Superior | ✅ C22 |
| Crevice Corrosion Temp | >50°C | >60°C | ✅ C22 |
| Cost | $$ (Standard) | $$$ (Premium) | ✅ C276 |
✔ Environment involves reducing acids (HCl, H₂SO₄) at elevated temperatures
✔ You need best-in-class resistance to hydrochloric acid
✔ Application is in chemical processing, flue gas desulfurization (FGD)
✔ Cost-effective — the industry standard for severe corrosion
✔ Environment involves oxidizing acids (HNO₃, mixed acids, ferric chloride)
✔ You need superior pitting and crevice corrosion resistance
✔ Application is in pharmaceutical, fine chemical, or waste treatment
✔ You require PREN > 65 for extreme chloride environments
🧪 Key Characteristics
Chemical Resistance
C276: Excels in reducing acids (HCl, H₂SO₄, H₃PO₄)
C22: Excels in oxidizing environments (HNO₃, wet Cl₂, FeCl₃)
Mechanical Strength
C276: Yield 283 MPa, Tensile 690 MPa
C22: Yield 310 MPa, Tensile 690 MPa
Both: >45% elongation
Industry Focus
C276: Chemical, FGD, pulp/paper
C22: Pharma, fine chemicals, offshore, pickle operations
📊 Detailed Specifications
| Specification | Hastelloy C276 | Hastelloy C22 |
|---|---|---|
| ASTM Plate/Sheet | B575 | B575 |
| ASTM Pipe/Tube | B622 / B619 / B626 | B622 / B619 / B626 |
| ASTM Bar | B574 | B574 |
| ASTM Forgings | B564 | B564 |
| Density | 8.89 g/cm³ | 8.69 g/cm³ |
| Melting Range | 1325-1370°C | 1357-1399°C |
| Max Service Temp | ≈1093°C (oxidizing) | ≈1093°C (oxidizing) |
| Critical Pitting Temp | >85°C | >100°C |
| Weldability | Excellent (ERNiCrMo-4) | Excellent (ERNiCrMo-10) |
🧪 Corrosion Performance in Common Acids
| Environment | C276 | C22 | Recommendation |
|---|---|---|---|
| Hydrochloric Acid (HCl) | ★★★★★ | ★★★★☆ | ✅ C276 |
| Sulfuric Acid (H₂SO₄) | ★★★★★ | ★★★★☆ | ✅ C276 |
| Nitric Acid (HNO₃) | ★★★☆☆ | ★★★★★ | ✅ C22 |
| Phosphoric Acid (H₃PO₄) | ★★★★★ | ★★★★☆ | ✅ C276 |
| Mixed Acids (HNO₃+HF) | ★★★☆☆ | ★★★★★ | ✅ C22 |
| Ferric Chloride (FeCl₃) | ★★★☆☆ | ★★★★★ | ✅ C22 |
| Wet Chlorine Gas | ★★★★☆ | ★★★★★ | ✅ C22 |
| Seawater / Brine | ★★★★★ | ★★★★★ | Equal |
📦 Available Product Forms
Sheets & Plates
Thickness: 0.3-100mm
Width: up to 2500mm
ASTM B575
Pipes & Tubes
OD: 6-630mm
WT: 0.5-50mm
ASTM B622/B619/B626
Bars & Fittings
Bars: 6-500mm Ø
Flanges / Elbows / Tees
ASTM B574/B564/B366
❓ Frequently Asked Questions
Q1: Can C276 and C22 be used interchangeably?
In reducing acid environments (HCl, H₂SO₄), C276 performs better. In oxidizing environments (HNO₃, mixed acids), C22 is superior. For general-purpose severe corrosion, either works — but specific environments demand one or the other.
Q2: Which is more expensive?
C22 is typically 10-15% more expensive than C276 due to higher chromium content and lower production volume. However, in oxidizing environments, C22’s superior performance may justify the premium.
Q3: What is PREN and why does it matter?
PREN = %Cr + 3.3×%Mo + 16×%N. Higher PREN = better pitting resistance. C276 ≥ 60; C22 ≥ 65. For high-chloride environments, choose the alloy with higher PREN.
Q4: What welding filler metals should I use?
C276: ERNiCrMo-4 (AWS A5.14). C22: ERNiCrMo-10 (AWS A5.14). Both offer excellent weldability with minimal pre/post-weld treatment.
Q5: What certifications come with your Hastelloy products?
Every shipment includes MTC (EN 10204 3.1) with full chemical & mechanical results. NACE MR0175 compliance. SGS/BV/TÜV inspection available.
Q6: Minimum order quantity?
Plate: from 1 sheet. Pipe: from 1 meter. Bar: from 1 piece. Extensive stock of C276 and C22 in common sizes. For custom dimensions, contact us.
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