Hastelloy C276 (Uns N10276) Alloy - Chemical Compositions, Mechanical Properties & Applications

by AMC

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Posted on May 21, 2024 at 03:57 PM

Hastelloy C276 is renowned as a nickel-molybdenum-chromium superalloy with added tungsten, crafted for unparalleled corrosion resistance in diverse and harsh environments. Its high nickel and molybdenum levels offer exceptional resistance to pitting and crevice corrosion in reducing conditions, while chromium enhances its resilience in oxidizing environments. The low carbon content prevents carbide precipitation during welding, ensuring sustained corrosion resistance in welded structures. Its resistance to grain boundary precipitates in the weld heat-affected zone makes it ideal for various chemical process applications in an as-welded state.

Corrosion Resistant Hastelloy C276 (Uns N10276)

Hastelloy C276 is renowned for its exceptional corrosion resistance, making it one of the most versatile alloys for harsh chemical environments. It stands strong against ferric and cupric chlorides, hot contaminated media, chlorine compounds, acids like formic and acetic, seawater, brine, and various chlorine-based solutions. Its resistance extends to grain boundary precipitates in welded zones, ensuring reliability in diverse chemical processes, while also excelling in pitting and stress corrosion cracking resistance.

Hastelloy C276 Chemical Composition

Ni	Mo	Cr	Fe	W	Co	Mn	C	V	P	S	Si
Remainder	15.0-17.0	14.5-16.5	4.0-7.0	3.0-4.5	2.5 max	1.0 max	.01 max	.35 max	.04 max	.03 max	.08 max

Hastelloy C276 Mechanical Properties

Product Form	Tensile (ksi)	.2% Yield (ksi)	Elongation %
Bar	110.0	52.6	62
Plate	107.4	50.3	67
Sheet	115.5	54.6	60
Tube & Pipe	105.4	45.4	70

Hastelloy C276 Physical Properties

Properties	Metric	Imperial
Density	8.89 g/cm³	0.321 lb/in³
Melting point	1371°C	2500°F

Hastelloy C276 Thermal Properties (Uns N10276)

Properties	Metric	Imperial
Thermal expansion co-efficient (@24-93°C/75.2-199°F)	11.2 µm/m°C	6.22 µin/in°F
Thermal conductivity (-168 °C)	7.20 W/mK	50.0 BTU in/hr.ft².°F

Equivalent Materials of Hastelloy C276 (Uns N10276)

ASTM B366	ASTM B574	ASTM B622	ASTM F467	DIN 2.4819
ASTM B575	ASTM B626	ASTM B619	ASTM F468

Characteristics of Hastelloy C276 (Uns N10276) include:

1. Excellent corrosion resistance in reducing environments.
2. Exceptional resistance to strong solutions of oxidizing salts, such as ferric and cupric chlorides.
3. High nickel and molybdenum contents providing good corrosion resistance in reducing environments.
4. Low carbon content which minimizes grain-boundary carbide precipitation during welding to maintain resistance to corrosion in heat-affected zones of welded joints.
5. Resistance to localized corrosion such as pitting and stress-corrosion cracking.
6. Ability to withstand the corrosive effects of wet chlorine gas, hypochlorite, and chlorine dioxide, making it one of the few materials suitable for such applications.

Fabrication and Heat Treatment of Hastelloy C276

Annealing

Hastelloy C276 is commonly utilized in its solution-treated state. The alloy is heated to 1121°C (2050°F) and then rapidly quenched for optimal performance.

Cold Working

Hastelloy C276 undergoes conventional cold working procedures for its cold working processes.

Welding

Hastelloy C276 (Uns N10276) can be welded using commonly used welding methods. It's important to avoid excessive heat input during welding. For corrosive applications, this alloy can often be used in its as-welded condition without requiring additional heat treatment.

Forging

Hastelloy C276 is forged or hot-upset using conventional methods.

Forming

Hastelloy C276 can be formed through cold working using conventional techniques.

Machinability

Hastelloy C276 exhibits good machinability characteristics.

Heat Treatment

Hastelloy C276 (Uns N10276) undergoes solution heat treatment at 1121°C (2050°F) followed by rapid quenching. For forged or hot-formed parts, solution heat treatment is recommended before use.

Hardening

Hastelloy C276 is hardened through cold working processes.

Hot Working

Hastelloy C276 can be extruded or hot-formed. After hot forming, it should undergo solution heat treatment.

Aging

Aging is not required for Hastelloy C276 used in a solution-treated condition.

 

Applications of Hastelloy C276 include:

• Digesters and bleach plants in the paper industry.

• Components exposed to sour gas.

• Equipment for flue-gas desulfurization plants.

• Evaporators, heat exchangers, filters, and mixers used in sulfuric acid environments.

• Sulfuric acid reactors.

• Organic chloride process equipment.

• Equipment for processes utilizing halide or acid catalysts.

Conclusion

Hastelloy C276 (Uns N10276) is a highly versatile and dependable superalloy, renowned for its exceptional corrosion resistance and durability in challenging environments. Its wide range of applications, from paper industry digesters to equipment for sulfuric acid environments, showcases its adaptability and reliability across diverse industries. With excellent machinability, weldability, and resistance to harsh conditions like sour gas exposure, Hastelloy C276 remains a top choice for critical components and processes where corrosion resistance and longevity are paramount.

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