Alloy C-276
Alloy C-276 / UNS N10276 / W.Nr. 2.4819
Description
Alloy C-276 is a solid solution strengthened nickel-molybdenum-chromium alloy with a small amount of tungsten. Alloy C-276 exhibits excellent corrosion resistance in a variety of harsh environments and media. Like many other nickel alloys, it is ductile, easily formed and welded. This alloy is used in most industrial settings where aggressive chemical environments are present and other alloys have failed.
Industries and Applications
Alloy C-276 is frequently used in many industries, including chemical and petrochemical processing, oil and gas, power generation, pharmaceutical, pulp and paper production and waste water treatment. End use applications include stack liners, ducts, dampers, scrubbers, stack gas reheaters, heat exchangers, reaction vessels, evaporators, transfer piping and many other highly corrosive applications.
Resistance to Corrosion
Alloy C-276 is one of the most universally corrosion resistant alloys available today. It is used in a variety of environments ranging from moderately oxidizing to strong reducing conditions. Alloy C-276 has exceptional resistance to sulfuric acid, hydrochloric acid, formic acid, acetic acid, chlorides, solvents, wet chloride gas, hypochlorite and chlorine solutions. Alloy C-276 has excellent resistance to phosphoric acid at all temperatures below boiling and concentrations lower than 65%. The limiting factor when dealing with strong oxidizing environments is the low chromium content, which means hot concentrated nitric acid environments are not desirable.
Alloy C-276 has superior resistance to pitting, stress corrosion cracking and oxidizing atmospheres. Alloy C-276 also exhibits resistance to corrosion by seawater in crevice conditions, which can induce aggressive attack in other commonly used materials.
Fabrication and Heat Treatment
Alloy C-276 can be formed using various cold and hot working processes. Like other nickel alloys, alloy C-276 work hardens quickly, though it can be cold formed using aggressive methods like deep drawing, press forming and punching. Hot forming should be performed within a temperature range between 1600°F and 2250°F (870°C and 1230°C) with heavier sections being heated to a minimum temperature of 2000°F before forming. Annealing of the material after working is advised and should be performed at a temperature between 2050°F and 2150°F, followed by a rapid quench in a protective atmosphere or agitated reducing quench bath. To obtain a reducing quench bath, add 2% (by volume) of either ethyl or propyl alcohol to water.
Common Trade Names
INCONEL® alloy C-276, Hastelloy® C-276 alloy
INCONEL® is a registered trademark of the Special Metals Corporation group of companies.
HASTELLOY® is a registered trademark of Haynes International Inc.
Alloy C-276 Chemical Composition (%)
(Ni) Nickel
Remainder
(Mo) Molybdenum
15.0 to 17.0
(Cr) Chromium
14.5 to 16.5
(Fe) Iron
4.0 to 7.0
(W) Tungsten
3.0 to 4.5
(Co) Cobalt
2.5 max
(Mn) Manganese
1.0 max
(V) Vanadium
0.35 max
(Si) Silicon
0.08 max
(P) Phosphorus
0.04 max
(S) Sulfur
0.03 max
(C) Carbon
0.010 max
Alloy C-276 Applicable Specifications*
Form
ASTM
ASME
VdTÜV
Bar
B574, B5641
SB574, SB5641
400
Plate & Sheet
B575
SB575
400
Welded Pipe
B619
SB619
-
Welded Tube
B626
SB626
-
Seamless Pipe & Tube
B622
SB622
-
Alloy C-276 Frequently Asked Questions
What is Alloy C-276 and why is it considered the industry standard for corrosion resistance?
Alloy C-276 is a nickel-molybdenum-chromium alloy with a small addition of tungsten, engineered to perform in highly aggressive chemical environments. It is widely regarded as an industry standard due to its outstanding resistance to pitting, crevice corrosion, and stress corrosion cracking across both oxidizing and reducing conditions where many other alloys fail.
What environments and chemicals is Alloy C-276 resistant to?
Alloy C-276 delivers exceptional performance in aggressive environments, including strong acids such as sulfuric, hydrochloric, formic, and acetic acids, as well as chloride-rich solutions. It also provides excellent resistance to wet chlorine gas, hypochlorite, and seawater, including crevice conditions, making it highly suitable for some of the most demanding industrial applications.
How does Alloy C-276 compare to stainless steels like 316L or 904L?
Alloy C-276 provides significantly higher corrosion resistance than stainless steels such as 316L or 904L, especially in high-chloride and acidic environments. While stainless steels are prone to pitting, crevice corrosion, and stress corrosion cracking, Alloy C-276 maintains durability and performance in conditions that typically degrade conventional materials.
What industries commonly use Alloy C-276?
Alloy C-276 is widely used in industries where corrosion resistance is essential, including chemical and petrochemical processing, oil and gas, power generation, pollution control, pharmaceuticals, pulp and paper, and wastewater treatment. Its reliability in critical systems makes it a preferred choice for continuous operations and demanding applications.
Is Alloy C-276 easy to fabricate and weld?
Yes, Alloy C-276 offers excellent ductility and weldability compared to many high-performance nickel alloys. It can be easily formed and welded using standard fabrication methods, making it suitable for complex components like vessels, piping systems, ducts, and fabricated assemblies without compromising corrosion resistance.
Are there any limitations or environments where Alloy C-276 is not recommended?
While Alloy C-276 performs exceptionally in most corrosive environments, it is not ideal for use in hot, concentrated nitric acid. In such conditions, alternative alloys may offer better long-term stability and corrosion resistance.