What Is Hastelloy C276? Composition, Properties, Applications, and Uses

What Is Hastelloy C276?

Hastelloy C276 is a nickel-based, corrosion-resistant alloy designed for demanding chemical processing and other environments where conventional stainless steels and lower-alloy materials may experience severe corrosion.

It is identified by UNS N10276 and Werkstoff Number 2.4819. The alloy belongs to the nickel-chromium-molybdenum family and contains significant amounts of molybdenum and tungsten. This combination gives Hastelloy C276 an unusually broad resistance to both reducing and oxidizing corrosive environments.

Hastelloy C276 is principally selected for its corrosion resistance, weldability, and resistance to localized corrosion. It is particularly valuable where equipment may encounter hydrochloric acid, sulfuric acid, chlorides, wet chlorine, hypochlorites, and mixed chemical streams.

For engineers and material specifiers, the simplest definition is:

Hastelloy C276 is a nickel-based corrosion-resistant alloy engineered for severe chemical environments where broad resistance to acids, chlorides, and localized corrosion is required.

For a broader technical overview covering composition, mechanical properties, corrosion resistance, welding, machining, standards, applications, and purchasing considerations, see the Ultimate Guide to Hastelloy C276.

Hastelloy C276 at a Glance

Exact chemical and mechanical requirements can vary with product form and applicable specification. Material should therefore be purchased and accepted against the relevant ASTM, ASME, or other project specification rather than relying solely on generic alloy data.

Is Hastelloy C276 a Nickel Alloy?

Yes. Hastelloy C276 is a nickel-based alloy, with nickel forming the balance of its chemical composition.

However, nickel alone does not explain the alloy's corrosion performance. The important feature is the interaction between several alloying elements.

Nickel

Nickel forms the primary matrix of C276 and contributes to its overall corrosion resistance, ductility, toughness, and stability in aggressive chemical environments.

Chromium

Chromium improves resistance to oxidizing environments and contributes to corrosion resistance in media containing oxidizing species.

Molybdenum

Molybdenum is one of the defining elements in C276. Its relatively high concentration contributes strongly to resistance against reducing acids and localized corrosion.

Tungsten

Tungsten provides additional solid-solution strengthening and contributes to corrosion resistance, particularly in aggressive localized-corrosion environments.

Low Carbon and Silicon

The low carbon and silicon levels are also important. They help reduce the tendency for undesirable precipitation during welding and support the alloy's corrosion performance in welded components.

Hastelloy C276 Chemical Composition

The nominal composition of Hastelloy C276 is dominated by nickel, chromium, molybdenum, and tungsten.

The relatively high molybdenum and tungsten contents distinguish C276 from many conventional stainless steels and nickel alloys.

The very low carbon content is particularly significant for fabricated equipment. It helps minimize carbide precipitation and associated corrosion problems in the heat-affected zone of welded components.

For a detailed element-by-element explanation, see Hastelloy C276 Chemical Composition, which should be treated as the primary supporting article for this topic.

Why Is Hastelloy C276 Highly Corrosion Resistant?

The principal reason engineers select Hastelloy C276 is its broad corrosion resistance.

Many engineering alloys perform very well in one particular environment but become vulnerable when the chemical conditions change. For example, an alloy may resist sulfuric acid but perform poorly in chloride-containing oxidizing conditions.

C276 was developed to provide a much broader corrosion envelope.

Its combination of nickel, chromium, molybdenum, and tungsten provides resistance to a range of:

• Reducing acids

• Oxidizing environments

• Chloride-containing solutions

• Pitting corrosion

• Crevice corrosion

• Stress-corrosion-related environments

• Wet chlorine-containing media

• Chemical process streams

Haynes International's technical data, for example, documents strong resistance of C276 to several inorganic acids, including hydrochloric and sulfuric acid under specified test conditions.

This does not mean that C276 is immune to every chemical under every temperature and concentration. Corrosion performance must always be evaluated against the actual process chemistry, concentration, temperature, contaminants, flow conditions, and fabrication condition.

For detailed engineering evaluation, see Hastelloy C276 Corrosion Resistance.

Hastelloy C276 Mechanical Properties

Although corrosion resistance is the primary reason for selecting C276, the alloy also offers useful mechanical properties.

For solution-annealed material at room temperature, commonly cited minimum values include approximately:

• Tensile strength: 690 MPa (100 ksi)

• Yield strength: 283 MPa (41 ksi)

• Elongation: 40%

These properties provide a combination of strength and ductility suitable for pressure-containing and fabricated chemical-processing components, subject to the applicable product specification and design code.

Mechanical properties can change with product form, thickness, heat treatment, and testing requirements. Therefore, engineers should use certified material test reports and the applicable specification when performing final design calculations.

For a deeper analysis, see Hastelloy C276 Mechanical Properties.

Hastelloy C276 Temperature Capability

Hastelloy C276 can operate across a wide temperature range, but its allowable service temperature cannot be reduced to a single universal number.

The correct temperature limit depends on:

1. Chemical environment

2. Stress level

3. Exposure duration

4. Oxidizing or reducing atmosphere

5. Product form

6. Applicable design code

7. Potential precipitation or phase instability

8. Required corrosion resistance

C276 maintains useful toughness at low temperatures and can be considered for certain cryogenic applications. At elevated temperatures, however, long-term exposure can influence microstructure and corrosion performance.

Therefore, statements such as "Hastelloy C276 can always operate at X°C" should be avoided when specifying material for an actual process system.

For detailed temperature considerations, see Hastelloy C276 Temperature Limits.

Is Hastelloy C276 Easy to Weld?

Compared with many highly alloyed corrosion-resistant materials, Hastelloy C276 has good weldability when appropriate procedures are followed.

Its low-carbon chemistry was specifically important in reducing the risk associated with carbide precipitation and corrosion in welded regions.

C276 can be welded using processes such as:

• GTAW/TIG

• GMAW/MIG

• SMAW

• Other qualified welding processes appropriate to the application

For matching welding applications, Haynes International identifies ERNiCrMo-4 filler metal for GTAW/GMAW applications and ENiCrMo-4 for shielded metal arc welding.

However, good alloy chemistry does not eliminate the need for proper fabrication control.

Welding procedures should address:

• Heat input

• Interpass temperature

• Surface cleanliness

• Shielding gas

• Back purging where required

• Filler metal selection

• Joint preparation

• Post-weld inspection

For fabrication teams, the dedicated Hastelloy C276 Welding Guide should provide the next level of technical detail.

Where Is Hastelloy C276 Used?

Hastelloy C276 is particularly common in industries where corrosion resistance is more important than minimizing initial material cost.

Chemical Processing

Chemical processing equipment is one of the most important application areas for C276.

It can be used for components such as:

• Process piping

• Heat exchangers

• Reactors

• Vessels

• Pumps

• Valves

• Fittings

• Scrubber components

The reason is straightforward: chemical plants may expose equipment to combinations of acids, chlorides, oxidizing compounds, and elevated temperatures.

Flue Gas Desulfurization

C276 is also used in selected flue gas desulfurization (FGD) environments, particularly where chloride-bearing wet scrubber conditions create a high risk of localized corrosion.

The combination of molybdenum, chromium, and tungsten provides a corrosion-resistant solution for demanding scrubber environments.

Acid Service

Hydrochloric acid and sulfuric acid service are important areas for C276.

The alloy's molybdenum-rich chemistry gives it strong resistance to many reducing acid environments, while chromium helps broaden its performance where oxidizing conditions are also present.

Pulp and Paper

Certain pulp and paper process streams contain aggressive chemicals and chlorides that can challenge conventional stainless steels.

C276 can be selected for equipment exposed to particularly severe chemical conditions.

Waste Treatment

Hazardous waste treatment and chemical waste processing can involve unpredictable mixtures of corrosive substances. A broad corrosion-resistant alloy can therefore be more appropriate than a material optimized for only one chemical.

Oil and Gas and Other Process Industries

C276 may also be considered for selected oil and gas, pollution-control, water-treatment, and other process applications where the actual service chemistry justifies the alloy's higher material cost.

The correct grade should always be selected from the complete service environment rather than from the industry name alone.

Hastelloy C276 Pipe, Tube, Plate, and Other Product Forms

Hastelloy C276 is available in multiple product forms, depending on manufacturer capabilities and applicable standards.

Common forms include:

• Seamless pipe

• Welded pipe

• Seamless tube

• Welded tube

• Plate

• Sheet

• Round bar

• Forgings

• Butt-weld fittings

• Flanges

• Welding wire and electrodes

For chemical processing systems, Hastelloy C276 pipe and tube are especially important because they can be fabricated into process piping, heat exchangers, reactor components, and other corrosion-resistant systems.

When purchasing C276 products, the buyer should specify more than simply "Hastelloy C276." The purchase specification should address:

• UNS designation

• Product form

• Dimensions

• Wall thickness

• Applicable ASTM/ASME specification

• Heat treatment condition

• Mechanical requirements

• Chemical requirements

• Testing and inspection requirements

• Certification requirements

Hastelloy C276 Standards

The appropriate material standard depends on the product form.

Examples of standards associated with nickel alloy products include ASTM/ASME specifications covering plate, sheet, strip, pipe, tube, fittings, forgings, and related products.

For example, C276 may appear under specifications such as:

• ASTM B574

• ASTM B575

• ASTM B619

• ASTM B622

• ASTM B626

• ASTM B366

• ASTM B564

The exact specification must be matched to the product being purchased. A pipe, plate, fitting, and forging should not automatically be ordered against the same ASTM standard.

For procurement teams, the supporting article ASTM Standards for Hastelloy C276 should be used to identify the appropriate specification by product form.

Hastelloy C276 vs Stainless Steel

One of the most common questions is whether Hastelloy C276 is "better" than stainless steel.

There is no universal answer.

C276 is generally selected when the corrosion environment is significantly more aggressive than the conditions that conventional stainless steel can economically tolerate.

For example, 316L stainless steel can be an excellent material for many chemical, food, marine, and industrial applications. However, severe combinations of chlorides, acids, temperature, and oxidizing/reducing conditions can exceed its practical corrosion envelope.

C276 has a much higher alloying content and is consequently more expensive.

Therefore:

Choose stainless steel when its corrosion performance is sufficient. Choose C276 when the process environment requires its broader corrosion resistance.

A material with a higher purchase price can sometimes reduce lifecycle cost if it prevents premature corrosion, leakage, shutdowns, or component replacement.

A dedicated comparison with 904L is covered in Hastelloy C276 vs Stainless Steel 904L.

Hastelloy C276 vs Other Nickel Alloys

C276 is not automatically the best nickel alloy for every application.

For example:

• Inconel 625 provides an excellent combination of corrosion resistance and mechanical strength and is widely used in marine, aerospace, chemical, and energy applications.

• Alloy 20 is often selected for sulfuric-acid-related applications where its corrosion performance and cost profile are appropriate.

• Incoloy 825 offers strong resistance in a variety of chemical and acidic environments and may be more economical for certain applications.

C276 distinguishes itself through its particularly broad resistance to complex and highly aggressive chemical environments.

The best alloy depends on the exact combination of:

chemical composition + concentration + temperature + pressure + contaminants + mechanical loading + fabrication requirements + lifecycle cost.

This is why direct alloy comparisons should always be based on service conditions rather than generic "better alloy" rankings.

What Is UNS N10276?

UNS N10276 is the Unified Numbering System designation for Hastelloy C276.

The designations can therefore be expressed as:

Hastelloy C276 = UNS N10276 = Werkstoff No. 2.4819

When purchasing or specifying material internationally, using the UNS designation can reduce ambiguity.

However, UNS N10276 identifies the alloy chemistry; it does not by itself define every requirement for a finished product.

For example, a buyer ordering C276 pipe still needs to identify the applicable product specification, dimensions, heat treatment, testing, and certification requirements.

Is Hastelloy C276 the Same as Hastelloy C?

No.

Hastelloy C276 is a later-generation alloy developed to improve the performance and fabrication characteristics of the original Hastelloy C family.

One of the important improvements was the reduction of carbon and silicon, which helped address precipitation-related corrosion problems associated with welding.

This distinction is important when reviewing older engineering documents or legacy equipment specifications. "Hastelloy C" and "Hastelloy C276" should not automatically be treated as interchangeable materials.

Advantages and Limitations of Hastelloy C276

Advantages

• Excellent resistance to many aggressive acids

• Strong resistance to chloride-induced localized corrosion

• Useful performance in both reducing and oxidizing environments

• Good weldability

• Good ductility

• High strength for a corrosion-resistant solid-solution alloy

• Available in multiple product forms

• Suitable for complex chemical-processing environments

Limitations

• Higher material cost than conventional stainless steels

• More difficult to machine than common steels

• Requires appropriate welding procedures

• Not immune to all highly oxidizing environments

• Corrosion performance depends strongly on temperature and chemical concentration

• Not necessarily the most economical choice for mild service

The engineering objective should therefore be fit-for-service material selection, not simply maximum alloy content.

Frequently Asked Questions About Hastelloy C276

What is Hastelloy C276?

Hastelloy C276 is a nickel-based chromium-molybdenum-tungsten alloy designed primarily for resistance to severe corrosion. It is identified as UNS N10276 and is widely used in chemical processing and other aggressive environments.

Is Hastelloy C276 stainless steel?

No. Hastelloy C276 is a nickel-based alloy, not a stainless steel. Its chemical composition contains substantially higher levels of nickel, molybdenum, and tungsten than conventional stainless steels.

What is the UNS number for Hastelloy C276?

The UNS designation for Hastelloy C276 is N10276.

What is Hastelloy C276 used for?

Common applications include chemical processing equipment, acid-service piping, flue gas desulfurization systems, pollution-control equipment, pulp and paper processing, waste treatment, and selected oil and gas applications.

Is Hastelloy C276 corrosion resistant?

Yes. C276 is specifically designed for severe corrosion resistance and performs well in many reducing and oxidizing environments, including numerous hydrochloric acid, sulfuric acid, chloride, and wet-chlorine conditions.

Is Hastelloy C276 weldable?

Yes. C276 can be welded using qualified GTAW, GMAW, SMAW, and other appropriate welding processes. Matching filler metals such as ERNiCrMo-4 are used for applicable welding applications.

Is Hastelloy C276 better than Inconel 625?

Neither alloy is universally better. C276 is particularly attractive for severe mixed-acid and localized-corrosion environments, while Inconel 625 provides an excellent balance of corrosion resistance, strength, and high-temperature capability. The correct choice depends on the service environment.

Is Hastelloy C276 expensive?

C276 is generally more expensive than common stainless steels because of its high nickel, molybdenum, and tungsten content. However, its higher initial cost can be justified when corrosion failure would result in significant maintenance, downtime, or replacement costs.