What Is Hastelloy?
Hastelloy is a high-performance nickel-based alloy family renowned for its exceptional corrosion resistance, high-temperature strength, and excellent fabricability in extreme industrial environments. Hastelloy alloys are widely used in chemical processing, oil & gas, aerospace, power generation, pollution control, and pharmaceutical industries, where conventional stainless steels or standard nickel alloys fail.
Originally developed by Haynes International, Hastelloy has become a benchmark material for corrosion-resistant alloys (CRAs), especially in applications involving strong acids, chlorides, high pressure, and elevated temperatures.
Hastelloy Definition (Technical Explanation)
Hastelloy refers to a group of nickel-based superalloys primarily alloyed with:
Chromium (Cr) – oxidation and corrosion resistance
Molybdenum (Mo) – resistance to pitting, crevice corrosion, and reducing acids
Iron (Fe) – structural stability and cost balance
Cobalt (Co), Tungsten (W), Aluminum (Al) – enhanced high-temperature strength
These alloys are engineered to provide outstanding resistance to uniform corrosion, localized corrosion, stress corrosion cracking (SCC), and high-temperature oxidation.
Exceptional Corrosion Resistance
Hastelloy alloys perform exceptionally well in:
Sulfuric acid
Hydrochloric acid
Nitric acid
Phosphoric acid
Mixed acid environments
Wet chlorine gas
Seawater and chloride-rich media
Compared with 316L stainless steel or Monel, Hastelloy offers significantly superior resistance to pitting corrosion, crevice corrosion, and SCC.
High-Temperature Strength & Stability
Hastelloy maintains:
High mechanical strength
Microstructural stability
Oxidation resistance
at temperatures up to 1000°C (1832°F), making it ideal for heat exchangers, reactors, and gas turbine components.
Excellent Fabricability & Weldability
Despite its high alloy content, Hastelloy can be:
Hot-worked and cold-worked
Machined with controlled tooling
Welded using standard GTAW / GMAW processes
This makes it suitable for complex fabricated equipment such as pressure vessels, columns, and piping systems.
Resistance to Stress Corrosion Cracking (SCC)
Hastelloy shows outstanding resistance to:
Chloride-induced SCC
High-pressure acidic environments
High-temperature aqueous systems
This property is critical in chemical reactors, offshore platforms, and refining units.
Common Hastelloy Grades – Technical Comparison Table
| Hastelloy Grade | UNS No. | Main Alloying Elements | Key Properties | Typical Applications |
|---|---|---|---|---|
| Hastelloy C-276 | N10276 | Ni–Cr–Mo–Fe | Excellent resistance to pitting, crevice corrosion & SCC; performs well in oxidizing & reducing media | Chemical reactors, heat exchangers, scrubbers, pressure vessels |
| Hastelloy C-22 | N06022 | Ni–Cr–Mo–W | Superior resistance to localized corrosion; outstanding performance in mixed acids | Heat exchangers, flanges, pharmaceutical equipment |
| Hastelloy C-2000 | N06200 | Ni–Cr–Mo–Cu | Excellent resistance to both oxidizing & reducing acids, especially sulfuric acid | Chemical processing equipment, acid recovery systems |
| Hastelloy X | N06002 | Ni–Cr–Fe–Mo | High-temperature strength and oxidation resistance up to ~1200°C | Gas turbines, aerospace components, furnace parts |
| Hastelloy B-2 | N10665 | Ni–Mo | Outstanding resistance to hydrochloric acid and reducing environments | Acid handling systems, reactors, piping |
| Hastelloy B-3 | N10675 | Ni–Mo | Improved thermal stability and intergranular corrosion resistance vs B-2 | Chemical reactors, heat exchangers |
| Hastelloy G-30 | N06030 | Ni–Cr–Fe–Mo–Cu | Excellent resistance to phosphoric & nitric acid | Fertilizer and chemical processing equipment |
| Hastelloy G-35 | N06035 | Ni–Cr–Mo–Cu | Enhanced sulfuric acid resistance | Chemical processing, acid plants |
| Hastelloy N | N10003 | Ni–Mo–Cr | Excellent high-temperature stability in molten salt environments | Nuclear & molten salt systems |
ASTM / UNS / EN Cross Reference Table – Hastelloy Alloys
| Hastelloy Grade | UNS No. | ASTM / ASME Standards (Common) | EN / DIN Equivalent | Typical Application Environment |
|---|---|---|---|---|
| Hastelloy C-276 | N10276 | ASTM B575 / B619 / B622 / B626 | EN 2.4819 | Mixed acids, chlorides, chemical reactors |
| Hastelloy C-22 | N06022 | ASTM B575 / B619 / B622 | EN 2.4602 | Pitting & crevice corrosion, heat exchangers |
| Hastelloy C-2000 | N06200 | ASTM B575 / B619 / B622 | EN 2.4675 | Sulfuric acid, oxidizing & reducing acids |
| Hastelloy C-4 | N06455 | ASTM B575 / B619 / B622 | EN 2.4610 | High-temperature corrosion resistance |
| Hastelloy B-2 | N10665 | ASTM B333 / B619 / B622 | EN 2.4617 | Hydrochloric acid, reducing environments |
| Hastelloy B-3 | N10675 | ASTM B333 / B619 / B622 | EN 2.4600 | Improved HCl resistance, better stability |
| Hastelloy G-30 | N06030 | ASTM B582 / B619 | EN 2.4603 | Phosphoric & nitric acid systems |
| Hastelloy G-35 | N06035 | ASTM B575 / B619 | EN 2.4645 | Sulfuric acid processing |
| Hastelloy X | N06002 | ASTM B435 / B619 / B622 | EN 2.4665 | High-temperature oxidation, gas turbines |
| Hastelloy XR | N06004 | ASTM B435 | EN 2.4665 (variant) | Gas turbine & furnace components |
| Hastelloy N | N10003 | ASTM B573 / B619 | EN 2.4816 | Molten salt & nuclear applications |
Hastelloy Chemical Composition Table
| Grade | UNS | Ni | Cr | Mo | Fe | Co | W | Cu | Mn | Si | C | Other |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hastelloy C-276 | N10276 | Bal. | 14.5–16.5 | 15.0–17.0 | 4.0–7.0 | ≤2.5 | 3.0–4.5 | - | ≤1.0 | ≤0.08 | ≤0.01 | V ≤0.35 |
| Hastelloy C-22 | N06022 | Bal. | 20.0–22.5 | 12.5–14.5 | 2.0–6.0 | ≤2.5 | 2.5–3.5 | - | ≤0.5 | ≤0.08 | ≤0.015 | - |
| Hastelloy C-2000 | N06200 | Bal. | 22.0–24.0 | 15.0–17.0 | ≤3.0 | ≤2.0 | - | 1.3–1.9 | ≤0.5 | ≤0.08 | ≤0.01 | - |
| Hastelloy C-4 | N06455 | Bal. | 14.0–18.0 | 14.0–17.0 | ≤3.0 | ≤2.0 | - | - | ≤1.0 | ≤0.08 | ≤0.01 | - |
| Hastelloy B-2 | N10665 | Bal. | ≤1.0 | 26.0–30.0 | ≤2.0 | ≤1.0 | - | - | ≤1.0 | ≤0.10 | ≤0.01 | - |
| Hastelloy B-3 | N10675 | Bal. | 1.0–3.0 | 26.0–30.0 | ≤3.0 | ≤3.0 | - | - | ≤1.0 | ≤0.10 | ≤0.01 | - |
| Hastelloy G-30 | N06030 | Bal. | 28.0–31.5 | 4.0–6.0 | 13.0–17.0 | ≤5.0 | - | 1.5–4.0 | ≤1.0 | ≤0.8 | ≤0.02 | - |
| Hastelloy G-35 | N06035 | Bal. | 32.0–35.0 | 7.0–9.0 | ≤1.0 | ≤1.0 | - | ≤0.5 | ≤1.0 | ≤0.6 | ≤0.01 | - |
| Hastelloy X | N06002 | Bal. | 20.5–23.0 | 8.0–10.0 | 17.0–20.0 | 0.5–2.5 | ≤1.0 | - | ≤1.0 | ≤1.0 | 0.05–0.15 | - |
| Hastelloy XR | N06004 | Bal. | 20.5–23.0 | 8.0–10.0 | 17.0–20.0 | 0.5–2.5 | ≤1.0 | - | ≤1.0 | ≤1.0 | ≤0.08 | La added |
| Hastelloy N | N10003 | Bal. | 6.0–8.0 | 15.0–18.0 | ≤5.0 | ≤0.2 | - | - | ≤1.0 | ≤0.5 | ≤0.05 | Al, Ti (trace) |
Role of Key Alloying Elements in Hastelloy
| Alloying Element | Primary Function | Impact on Corrosion Resistance |
|---|---|---|
| Nickel (Ni) | Stabilizes austenitic structure | Excellent resistance to general corrosion and high-temperature acids |
| Chromium (Cr) | Forms protective passive oxide film | Resistance to oxidation, pitting, and crevice corrosion |
| Molybdenum (Mo) | Suppresses anodic dissolution | Outstanding resistance to reducing acids and localized corrosion |
| Tungsten (W) | Enhances Mo effectiveness | Improved stability in severe acid environments |
| Copper (Cu) | Modifies electrochemical behavior | Significantly improves sulfuric acid resistance |
| Iron (Fe) | Structural stability, cost balance | Neutral effect on corrosion resistance |
| Low Carbon / Silicon | Minimizes carbide precipitation | Improved weldability and intergranular corrosion resistance |
Engineering Insight:
Mo & W → reducing acid resistance
Cr → oxidizing media & chloride pitting resistance
Cu → sulfuric acid performance
Composition vs Corrosion Media Performance
| Hastelloy Grade | Composition Focus | Chlorides | Hydrochloric Acid | Sulfuric Acid | Mixed Acids | High-Temperature Oxidation |
|---|---|---|---|---|---|---|
| C-276 | High Mo + W | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| C-22 | High Cr + Mo | ⭐⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ |
| C-2000 | Cr + Mo + Cu | ⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐ |
| B-2 | Very high Mo, low Cr | ⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐ | ⭐ | ⭐⭐ |
| B-3 | Mo with improved thermal stability | ⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐ | ⭐ | ⭐⭐ |
| G-30 | High Cr + Cu | ⭐⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐ |
| G-35 | Very high Cr | ⭐⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐⭐ | ⭐⭐⭐ | ⭐⭐⭐ |
| Hastelloy X | Cr + Fe (high-temperature alloy) | ⭐⭐ | ⭐ | ⭐⭐ | ⭐⭐ | ⭐⭐⭐⭐⭐ |
Best Hastelloy Chemistry for Different Corrosion Mechanisms
Chloride Pitting & Crevice Corrosion
Key elements: High Cr + Mo (+ W)
Recommended grades: C-22, C-276
Typical applications:
Seawater systems
Heat exchanger tubing
Wet chlorine environments
Strong Reducing Acids (Especially HCl)
Key elements: Very high Mo, low Cr
Recommended grades: B-2, B-3
Typical applications:
Hydrochloric acid reactors
Acid pickling equipment
⚠ Not recommended for oxidizing or mixed-acid environments
Sulfuric Acid Systems
Key elements: Cu + Cr
Recommended grades: C-2000, G-30, G-35
Typical applications:
Sulfuric acid concentration units
Fertilizer plants
Acid recovery systems
Mixed or Uncertain Chemical Media
Key elements: Balanced Cr–Mo design
Recommended grades: C-276, C-22
Advantages:
Broad corrosion resistance window
High tolerance to process fluctuations
Preferred "safe choice" in engineering design
High-Temperature Oxidizing Environments
Key elements: Cr + Fe with solid-solution strengthening
Recommended grade: Hastelloy X
Typical applications:
Gas turbines
Furnace components
Aerospace hot-section parts
Our factory
Have questions about Hastelloy alloys or need a custom quote? Our team of experts is ready to assist you.
Our address
Room 4107, Runfeng Building, Sanqiao New Street, Weiyang District, Xi'an City, Shaanxi Province
Phone Number
+86 15769214734
Hastelloy Composition & Corrosion Resistance – FAQ
1. What is Hastelloy made of?
Hastelloy is a nickel-based alloy primarily composed of Nickel (Ni), Chromium (Cr), and Molybdenum (Mo), with optional additions of Tungsten (W), Copper (Cu), Iron (Fe), and trace elements.
The exact composition varies by grade to target specific corrosion mechanisms.
2. Why does Hastelloy have better corrosion resistance than stainless steel?
Hastelloy contains much higher levels of Mo and Ni than stainless steels.
Mo provides superior resistance to reducing acids and crevice corrosion
Ni ensures stability in high-temperature and acidic environments
Cr enhances oxidation and pitting resistance
This combination allows Hastelloy to outperform 304/316 stainless steel in aggressive chemical conditions.
3. Which Hastelloy grade is best for hydrochloric acid (HCl)?
Hastelloy B-2 and B-3 are the best choices for hydrochloric acid due to their very high molybdenum content and low chromium levels.
⚠ These grades should not be used in oxidizing or mixed-acid environments.
4. Which Hastelloy alloy is best for sulfuric acid?
For sulfuric acid service, grades containing Copper (Cu) perform best:
Hastelloy C-2000
Hastelloy G-30
Hastelloy G-35
Copper significantly improves resistance to sulfuric acid corrosion, especially at medium to high concentrations.
5. How does chromium affect Hastelloy corrosion performance?
Chromium forms a protective passive oxide layer, improving resistance to:
Oxidizing environments
Chloride pitting
Crevice corrosion
Grades with higher chromium content, such as C-22, offer superior protection in chloride-rich media.
6. What role does molybdenum play in Hastelloy alloys?
Molybdenum is critical for:
Resistance to reducing acids
Protection against localized corrosion
Improved performance in high-chloride environments
Higher Mo content generally means better performance in harsh chemical processes.
7. Is Hastelloy resistant to stress corrosion cracking (SCC)?
Yes. Most Hastelloy grades exhibit excellent resistance to chloride-induced stress corrosion cracking, making them ideal for:
Heat exchangers
Offshore and marine systems
Chemical reactors
8. Which Hastelloy grade should be chosen for mixed or unknown chemical environments?
When the corrosion environment is complex or uncertain, Hastelloy C-276 or C-22 is typically recommended.
These grades offer the widest corrosion resistance range and are often considered "safe choice" alloys in engineering design.
9. How does Hastelloy perform at high temperatures?
Certain Hastelloy grades maintain strength and oxidation resistance at elevated temperatures:
Hastelloy X is optimized for high-temperature structural applications such as gas turbines and furnaces.
Corrosion-focused grades (C-series) also retain good properties at moderately high temperatures.
10. Is Hastelloy difficult to fabricate or weld?
Despite its high alloy content, Hastelloy offers:
Good weldability (GTAW, GMAW commonly used)
Good hot and cold workability with proper procedures
Low carbon and controlled chemistry help reduce the risk of intergranular corrosion after welding.
11. Why is Hastelloy more expensive than other alloys?
Hastelloy costs more due to:
High nickel and molybdenum content
Complex melting and processing
Superior performance in extreme environments
However, it often provides lower total lifecycle cost through longer service life and reduced maintenance.
12. Who originally developed Hastelloy?
Hastelloy alloys were originally developed and commercialized by Haynes International and are now widely specified under ASTM / ASME / UNS / EN standards.
