Quick Answer
C22 wins in most oxidizing environments. C276 remains the industry standard with wider availability and lower cost. Choose C22 when you need superior resistance in mixed oxidizing/reducing conditions. Choose C276 for proven reliability in reducing acid service.
Chemical Composition Comparison
| Element | C276 (N10276) | C22 (N06022) | Difference |
|---|---|---|---|
| Nickel (Ni) | Bal. | Bal. | Same |
| Chromium (Cr) | 14.5–16.5% | 20.0–22.5% | C22: +37% |
| Molybdenum (Mo) | 15.0–17.0% | 12.5–14.5% | C276: +18% |
| Tungsten (W) | 3.0–4.5% | 2.5–3.5% | Similar |
| Iron (Fe) | 4.0–7.0% | 2.0–6.0% | Similar |
| Carbon (C) | ≤0.01% | ≤0.015% | Similar |
Key insight: C22's higher chromium (22% vs 16%) gives it superior resistance in oxidizing environments. C276's higher molybdenum provides an edge in reducing acids.
Corrosion Resistance: Head-to-Head
| Environment | C276 | C22 | Winner |
|---|---|---|---|
| Concentrated HCl (reducing) | ★★★★☆ | ★★★☆☆ | C276 |
| Concentrated H2SO4 (oxidizing) | ★★★☆☆ | ★★★★★ | C22 |
| Mixed HNO3 + HCl (aqua regia) | ★★★☆☆ | ★★★★★ | C22 |
| Seawater / Cl⁻ pitting | ★★★★☆ | ★★★★★ | C22 |
| Flue gas desulfurization | ★★★★☆ | ★★★★★ | C22 |
| Wet chlorine / hypochlorite | ★★★★★ | ★★★★☆ | C276 |
| Organic acids (acetic, formic) | ★★★★☆ | ★★★★★ | C22 |
Mechanical Properties
| Property | C276 | C22 |
|---|---|---|
| Tensile Strength (MPa) | 690 | 690 |
| Yield Strength (MPa) | 283 | 310 |
| Elongation (%) | 40 | 45 |
| Max Service Temp (°C) | 1093 | 1093 |
Mechanical properties are nearly identical. C22 has a slight edge in ductility (45% vs 40% elongation), making it somewhat easier to form.
Price Comparison (May 2026)
| Product Form | C276 Price/kg | C22 Price/kg | Premium |
|---|---|---|---|
| Plate (6mm) | $42–48 | $50–60 | +20–25% |
| Sheet (2mm) | $45–52 | $55–65 | +22–25% |
| Pipe (SCH40) | $55–70 | $68–85 | +20–24% |
| Bar (Ø25mm) | $38–45 | $48–55 | +22–26% |
| Welding Wire | $60–75 | $75–90 | +20–25% |
When to Choose C276
✅ Best for:
• Reducing acid service (HCl, H2SO4 below 50%)
• Wet chlorine and hypochlorite environments
• Projects with tight budgets (15-25% savings vs C22)
• When fast delivery matters (C276 has wider stock availability)
• Existing designs with C276 track record
When to Choose C22
✅ Best for:
• Mixed oxidizing/reducing acid environments
• Flue gas desulfurization (FGD) systems
• Seawater heat exchangers
• Chemical reactors with varying acid mixtures
• When superior pitting resistance is critical
• Long-term CAPEX optimization (C22 lasts longer → fewer replacements)
Frequently Asked Questions
C22 offers superior corrosion resistance in most environments due to its higher chromium content (22% vs 16%), but C276 remains the better choice for reducing acid environments and has wider availability at lower cost. There is no universal "better" — it depends on your specific service conditions.
C22 typically costs 15-25% more than C276 due to higher chromium content and lower production volume. As of May 2026, C276 plate runs $42-48/kg while C22 plate is $50-60/kg.
In most oxidizing environments, yes. C22 outperforms C276 in oxidizing acid mixtures. However, in concentrated reducing acids (like HCl), C276 may still be preferred. Always verify with your corrosion engineer before substitution.
Both alloys have excellent weldability. C276 does not require post-weld heat treatment, and C22 shares this advantage. C22 may have slightly less sensitization in the heat-affected zone due to its lower carbon equivalent.
C276 = UNS N10276 (W.Nr. 2.4819), C22 = UNS N06022 (W.Nr. 2.4602).
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