Inconel 625 vs Hastelloy C-276
Both are premium nickel alloys for extreme environments — but they are optimized for different types of corrosion. C-276 dominates in reducing acids; 625 excels at high-temperature oxidation and strength.
| Property | Inconel 625 | Hastelloy C-276 |
|---|---|---|
| UNS | N06625 | N10276 |
| Nickel | ≥ 58.0% | ≥ 57.0% |
| Chromium | 20.0 – 23.0% | 14.5 – 16.5% |
| Molybdenum | 8.0 – 10.0% | 15.0 – 17.0% |
| Tungsten | — | 3.0 – 4.5% |
| Niobium | 3.15 – 4.15% | — |
| Tensile Strength | ≥ 827 MPa (120 ksi) | ≥ 690 MPa (100 ksi) |
| Yield Strength | ≥ 414 MPa (60 ksi) | ≥ 283 MPa (41 ksi) |
| Max Service Temp | 980°C | 1093°C |
| PREN | > 45 | > 65 |
| Oxidizing Resistance | Very good | Good (C-22 better for oxidizing) |
| Reducing Resistance | Good | Excellent (best in class) |
| Weldability | Excellent | Very good |
| Relative Cost | 1.0× (base) | 1.15 – 1.25× |
Choose Inconel 625 When:
- High-temperature strength required (> 650°C)
- Aerospace and gas turbine components
- Subsea umbilicals and control lines
- Oxidizing environments (nitric acid, wet chlorine)
- NACE sour service with mechanical loads
Choose Hastelloy C-276 When:
- Hot HCl, H₂SO₄, or mixed acids
- Wet chlorine gas and hypochlorite
- Flue gas desulfurization (FGD) scrubbers
- Chemical reactors with unpredictable process streams
- Reducing environments (the universal solvent)
The Bottom Line
625 is an engineer's alloy — optimized for strength, fatigue resistance, and high-temperature oxidation with good general corrosion resistance. C-276 is a chemist's alloy — optimized for universal corrosion resistance including the most aggressive reducing acids. For chemical processing with unknown or variable process streams, C-276 is the safer choice. For mechanical components that happen to need corrosion resistance, 625 is stronger and more fatigue-resistant.