Excellent Corrosion Resistance of Hastelloy C22
Hastelloy C22 is a versatile Ni‑Cr‑Mo‑Fe alloy that provides outstanding resistance to both oxidizing and reducing media. It shows exceptional immunity to pitting, crevice corrosion, and stress‑corrosion cracking and frequently outperforms C276 in strongly oxidizing environments—making it ideal for the harshest service conditions.
What is Hastelloy C22?
Hastelloy C22 is a high‑alloy, nickel‑based corrosion‑resistant material engineered to withstand aggressive oxidizing and reducing environments simultaneously. Its high chromium content (≈ 20‑22 %) combined with balanced molybdenum and iron gives broad resistance to acidic solutions, chloride‑bearing media, and a wide variety of organic and inorganic chemicals.
Hastelloy C22 Equivalent Grades
| Standard / System | Designation |
| UNS | N06022 |
| W.Nr. | 2.4602 |
| ASTM | B575 / B622 / B619 / B366 / B564 |
| JIS | NW6022 |
| ISO / DIN | NiCr21Mo14W |
Hastelloy C22 Chemical Composition
| Element | Content (%) |
| Nickel (Ni) | Balance (~56 %) |
| Chromium (Cr) | 20.0 – 22.5 |
| Molybdenum (Mo) | 12.5 – 14.5 |
| Iron (Fe) | 2.0 – 6.0 |
| Tungsten (W) | 2.5 – 3.5 |
| Cobalt (Co) | ≤ 2.5 |
| Carbon (C) | ≤ 0.015 |
| Silicon (Si) | ≤ 0.08 |
| Manganese (Mn) | ≤ 0.5 |
| Sulfur (S) | ≤ 0.02 |
Hastelloy C22 Mechanical Properties (Annealed, Room Temperature)
| Property | Typical Value |
| Tensile Strength | ≥ 690 MPa |
| Yield Strength (0.2 % offset) | ≥ 283 MPa |
| Elongation | ≥ 45 % |
| Brinell Hardness | ≤ 250 HB |
Hastelloy C22 Physical Properties
| Property | Value |
| Density | 8.69 g/cm³ |
| Solidus / Liquidus | ~1350 °C |
| Thermal Conductivity (RT) | ~9.0 W m⁻¹ K⁻¹ |
| Electrical Resistivity | ~1.15 µΩ·m |
| Specific Heat | 0.40 J g⁻¹ K⁻¹ |
| Magnetism | Non‑magnetic |
Applications of Hastelloy C22
- Chemical reactors, piping, and storage vessels
- Pharmaceutical equipment and high‑purity systems
- Flue‑gas desulfurization (FGD) units
- Seawater‑desalination and chloride‑rich water systems
- Heat exchangers, valves, and pumps in chloride/high‑temperature acid service
- Bleaching equipment in the pulp‑and‑paper industry
Advantages of Hastelloy C22
- Simultaneous resistance to strong oxidizers and reducers
- Superior pitting, crevice‑corrosion, and SCC resistance
- High‑chromium design enhances performance in nitric acid, FeCl₃, etc.
- Excellent weldability and formability
- Thermally stable for elevated‑temperature corrosive service
Limitations of Hastelloy C22
- Higher cost than stainless steels and conventional Ni alloys
- Potential pitting risk in stagnant, high‑chloride crevices
- Mechanical strength drops at very high temperatures
- Rapid work‑hardening during cold forming requires process control
How is Hastelloy C22 Manufactured?
- Raw‑Material Melting – High‑purity Ni, Cr, Mo, etc. melted in VIM or ESR furnaces for chemistry control.
- Casting – Molten alloy poured into ingots or continuous‑cast billets.
- Hot Working – Hot‑rolled, forged, or extruded at 1100–1200 °C into plates, bars, tubes, etc.
- Annealing – Homogenizing at ~1100 °C to relieve stress, refine grains, and optimize corrosion resistance.
- Cold Working – Cold rolling/drawing for final dimensions, tight tolerance, and enhanced strength.
- Quality Control – Mechanical tests, chemical analysis, corrosion testing, and NDT (UT/RT/PT) to ASTM, ASME, and NACE standards.
Hastelloy C22 vs C276 – Quick Comparison
| Category | Hastelloy C22 | Hastelloy C276 |
| UNS Number | N06022 | N10276 |
| Cr Content | 20–22.5 % | 14.5–16.5 % |
| Mo Content | 12.5–14.5 % | 15–17 % |
| W Content | 2.5–3.5 % | 3–4.5 % |
| Oxidizing‑Media Resistance | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| Overall Corrosion Resistance | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ |
| Fabrication / Welding | Excellent | Very good |
| Ideal Uses | Strong oxidizers, high‑purity chemical systems | General severe corrosion, high‑temperature acid service |
FAQ About Hastelloy C276
C22 contains more chromium (~22 % vs. ~16 %), giving it better resistance in strongly oxidizing media. C276 is more universally resistant in mixed media but slightly less effective against powerful oxidizers.
Yes. Use matching filler metal (ERNiCrMo‑10) with TIG, MIG, or SMAW; control heat input to prevent sensitization.
Approximately –196 °C to 1040 °C, depending on environment and code requirements.
No. It remains non‑magnetic in all conditions.
Summary
This article introduces Hastelloy C22, explains the alloy, and discusses its composition, properties, and applications. For more information about Hastelloy C22, please get in touch with an MT.BOLTS representative.
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