Can Hastelloy C-276 resist alkali corrosion?
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Alkali solution concentration: 5-10%, temperature: 200-280 degrees. An experimental apparatus in our unit has been operating under such conditions for over a year, and branch-like cracks have appeared on its inner wall. I would like to ask everyone, what could be the reason? Thank you all
Theoretically, 276 pairs of low- and medium-temperature sulfuric acids and oxidizing salts exhibit good corrosion resistance
Dendritic cracks are a prominent manifestation of alkali stress corrosion cracking. Temperatures in the range of 200–280 degrees are considered quite high; alkaline solutions above 120 degrees cause severe corrosion of carbon steel. However, a concentration of 5–10% is not considered high. Nickel-based alloys are regarded as effective materials against alkali embrittlement, which is why Inconel is recommended as a steel with good corrosion resistance in such environments.
Theoretically, the material should be resistant to alkalis; I really don’t know what caused such corrosion.
Theoretically, the material should be resistant to alkalis. If your company has any needs, feel free to contact me
Hastelloy C-276 (UNS N10276) in the form of sheets, pipes, forgings, and round bars. Chemical composition of Hastelloy C-276: Alloy % Nickel Chromium Molybdenum Iron Molybdenum Nickel Carbon Manganese Silicon Molybdenum Phosphorus Sulfur Minimum values for Hastelloy C: 14.5 15 4 3; Maximum values: 16.5 17 7 4.5 2.5 0.08 1 1 0.35 0.04 0.03. Minimum values for C276: 14.5 15 4 3; Maximum values: 16.5 17 7 4.5 2.5 0.01 1 0.08 0.35 0.04 0.03. Physical properties of Hastelloy C-276: Density – 8.9 g/cm3; Melting point – 1325–1370 °C. Minimum mechanical properties of this alloy at room temperature: Alloy and condition Tensile strength Rm, N/mm2 Yield strength RP0.2, N/mm2 Elongation A5, %: Hastelloy C/C276 – 690 283 40. This alloy possesses the following characteristics: 1. It exhibits excellent corrosion resistance against most corrosive agents, both in oxidizing and reducing environments. 2. Excellent resistance to pitting corrosion, crevice corrosion, and stress corrosion cracking. Microstructural structure of Hastelloy C-276: C276 has a face-centered cubic crystal structure. Corrosion resistance of Hastelloy C-276: The C276 alloy is suitable for various chemical processing industries involving oxidizing and reducing media. The higher contents of molybdenum and chromium enable the alloy to resist corrosion by chloride ions, while tungsten further enhances its corrosion resistance. C276 is one of the few materials capable of withstanding corrosion by humid chlorine, hypochlorite, and chlorine dioxide solutions; this alloy exhibits significant corrosion resistance to high-concentration chloride solutions (such as ferric chloride and copper chloride). Applications of Hastelloy C-276: This alloy is widely used in the chemical and petrochemical industries, for example in components that come into contact with chlorinated organic compounds as well as in catalytic systems. This material is particularly suitable for use in high-temperature environments, as well as in environments with impurities present in inorganic and organic acids such as formic acid and acetic acid, as well as in seawater corrosion conditions. Other application areas for Hastelloy C-276: 1. The pulp and paper industry, such as vessels used for cooking and bleaching; 2. Wash towers, reheaters, wet steam fans, etc., in FGD systems; 3. Equipment and components that operate in environments with acidic gases; 4. Reactors for acetic acid and other acidic products; 5. Sulfuric acid condensers; 6. Methylene diphenyl isocyanate (MDI); 7. Production and processing of impure phosphoric acid
Hastelloy is primarily resistant to acid corrosion
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Hastelloy C-276 belongs to the class of nickel-based corrosion-resistant alloys (Hastelloy alloys). This material is extremely expensive; it is equivalent to 00Cr16Ni60Mo16W4V in China
Hastelloy C276 is not recommended for use in sodium hydroxide; there are many cheaper materials available at low temperatures, and its corrosion rate is high at high temperatures due to selective corrosion (molybdenum loss)