When it comes to selecting the right material for harsh environments involving aggressive chemicals, high temperatures, and marine exposure, nickel-based alloys are among the top choices. Two commonly used grades in this category are Alloy C276 and Alloy 400. While both offer excellent corrosion resistance and mechanical strength, they are engineered for different environments and applications.
In this article, we explore the key differences between Alloy C276 and Alloy 400, comparing their composition, mechanical properties, corrosion resistance, applications, and more. By the end, you’ll understand which alloy is better suited for your specific industry needs.
What Is Alloy C276?
Alloy C276 is a nickel-molybdenum-chromium superalloy developed for extreme corrosion resistance. It belongs to the Hastelloy family, trademarked by Haynes International, and is also known as Hastelloy C-276.
Key Characteristics of Alloy C276:
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Excellent resistance to strong oxidizers and reducers
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Superior performance in chloride-containing environments
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Great resistance to pitting, crevice corrosion, and stress corrosion cracking
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Weldable without post-weld heat treatment
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Suitable for harsh chemical processing applications
What Is Alloy 400?
Alloy 400, also known as Monel 400, is a nickel-copper alloy known for its excellent resistance to seawater and hydrofluoric acid. It was one of the earliest nickel alloys developed and is still widely used in marine and chemical processing industries.
Key Characteristics of Alloy 400:
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High resistance to seawater, salt brine, and HF acid
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Outstanding mechanical properties at sub-zero temperatures
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Good thermal conductivity
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Excellent resistance to alkalis
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Weldable and easy to fabricate
Chemical Composition Comparison
| Element | Alloy C276 (%) | Alloy 400 (%) |
|---|---|---|
| Nickel (Ni) | 57 min (Balance) | ≥63 (Balance) |
| Molybdenum (Mo) | 15-17 | – |
| Chromium (Cr) | 14.5-16.5 | – |
| Iron (Fe) | 4-7 | 2.5 max |
| Copper (Cu) | ≤0.5 | 28-34 |
| Tungsten (W) | 3-4.5 | – |
| Carbon (C) | ≤0.01 | ≤0.3 |
Summary:
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C276 is a nickel-molybdenum-chromium-tungsten alloy, ideal for highly corrosive chemical environments.
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400 is a nickel-copper alloy, best for marine and mildly corrosive applications.
Corrosion Resistance Comparison
Alloy C276:
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Excellent in oxidizing and reducing agents
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Superior performance in chlorides, acids, and oxidizers
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Great for wet chlorine gas, ferric/ cupric chlorides, hypochlorites, and strong organic acids
Alloy 400:
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Excellent in marine environments, saltwater, and alkaline conditions
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Good resistance to hydrofluoric acid, sulfuric acid, and non-oxidizing environments
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Not suitable for oxidizing agents such as nitric acid
Conclusion:
Use Alloy C276 in chemical processing involving aggressive media; use Alloy 400 in marine, oil & gas, and alkaline settings.
Mechanical Properties
| Property | Alloy C276 | Alloy 400 |
|---|---|---|
| Tensile Strength (MPa) | 690 min | 550-620 |
| Yield Strength (MPa) | 283 min | 170-345 |
| Elongation (%) | ≥40 | 35-40 |
| Hardness (HB) | ≤241 | ~130-180 |
| Melting Point (°C) | 1325-1370 | 1300-1350 |
Alloy C276 has higher strength and hardness, making it better suited for demanding structural applications under stress.
Applications of Alloy C276 vs. Alloy 400
Alloy C276 Applications:
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Chemical processing plants
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Pollution control equipment
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Pulp and paper bleach systems
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Waste treatment
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Flue gas scrubbers
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High-chloride environments
Alloy 400 Applications:
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Marine hardware and equipment
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Heat exchangers
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Chemical storage tanks
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Oil and gas extraction
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Pump shafts and valves
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Power plants
Weldability and Fabrication
Both alloys offer good weldability, but:
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C276 requires careful control due to its complex alloying elements. Welds retain corrosion resistance without post-weld heat treatment.
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400 is easier to machine and weld, particularly for basic fabrication tasks in non-acidic environments.
Cost and Availability
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Alloy C276 is significantly more expensive due to its complex composition and high-performance properties.
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Alloy 400 is more cost-effective and easier to source in larger volumes for general-purpose use.
For applications with budget constraints and mild corrosive conditions, Alloy 400 is a smart choice. For critical corrosion resistance, Alloy C276 is worth the investment.
Which Alloy Should You Choose?
| Application Need | Recommended Alloy |
|---|---|
| Chloride resistance | Alloy C276 |
| Marine environments | Alloy 400 |
| High strength and hardness | Alloy C276 |
| Resistance to hydrofluoric acid | Alloy 400 |
| Oxidizing chemicals | Alloy C276 |
| Cost-effective corrosion resistance | Alloy 400 |
| Extreme chemical processing | Alloy C276 |
Trusted Supplier for Alloy C276 and Alloy 400 – sasaalloy
Whether you’re working in offshore drilling, power generation, or chemical production, selecting the right alloy is vital. At sasaalloy, we supply:
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Certified Alloy C276 and Alloy 400 plates, tubes, bars, and fittings
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Cut-to-size services and custom orders
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Full traceability and MTC (EN 10204 3.1/3.2)
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Technical support and rapid global delivery
With extensive experience in nickel alloys and specialty metals, sasaalloy is your partner for high-performance, corrosion-resistant materials.
Conclusion
What is the difference between Alloy C276 and Alloy 400?
In summary:
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Alloy C276 is a high-performance nickel-molybdenum-chromium alloy designed for the most corrosive and acidic environments.
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Alloy 400 is a nickel-copper alloy best suited for marine and mildly corrosive applications.
Both alloys are exceptional in their own ways, and the right choice depends on your operational environment, corrosion challenges, and budget.
For quality material, expert guidance, and fast delivery, trust sasaalloy to meet your alloy needs worldwide.
Post time: Aug-05-2025