The first wrought nickel-chromium material to ease welding concerns, Hastelloy C-276 alloy (UNS N10276) is widely used in an array of chemical processes and associated industries. Similar to other nickel alloys, C-276 is ductile, easy to form and weld, and possesses exceptional resistance to stress corrosion cracking in chloride-bearing solutions.
Hastelloy C276 is a nickel-molybdenum-chromium superalloy with an addition of tungsten. This makes the C-276 material’s properties excellent to corrosion resistance in the most severe environments. Alloy C276 can also resist corrosion in both, oxidizing and reducing environments.
Alloy C-276 is resistant to general corrosion, stress corrosion cracking, pitting and crevice corrosion in a wide range of surroundings. Due to low carbon content, C-276 minimizes carbide precipitation during the welding process, maintaining resistance against inter-granular attacks in the heat-affected zones of welded joints.
From sulfuric acid to hydrochloric acid, Alloy C-276 has exceptional resistance. It opposes a large number of media experienced in chemical processing. Some of the varied media include acid chlorides, solvents, formic and acetic acids, acetic anhydride, wet chlorine gas, hypochlorites, and chlorine solutions. There is also reducing and oxidizing acids, neutralizing etc. that is resisted.
In addition to its king-like corrosion powers, Hastelloy has excellent resistance to phosphoric acid containing solution. Hastelloy C276 exhibits outstanding resistance to seawater corrosion particularly under crevice conditions. This often induces an attack in other commonly used materials such as 316 stainless steel, MONEL alloy 400, and INCONEL alloy 625.
INCONEL alloy C-276 or hastelloy is very helpful for flue gas desulfurization (FGD) systems to control air pollution from electric power plants. This alloy is also used for various applications including scrubbers, ducting and stack liners, stack-gas reheaters, fans and fan housings.
Scrubber liquors and gas condensates generally contain chlorides and the amount of chloride level frequently decides the corrosion behavior of the materials. Therefore, Alloy C-276 has been shown to withstand higher chloride content than other alloys before the beginning of limited corrosion in created scrubber environment.
Alloy C-276 is one of the premier materials for recovery and handling of “sour” natural gas, which contains hydrogen sulfide and often carbon dioxide and chlorides. These gases can be extremely corrosive to carbon and alloy steels, and may cause brittle failure of many alloys due to sulfide stress cracking or stress-corrosion cracking.
The high levels of nickel, chromium, and molybdenum in alloy C-276 make the alloy resistant to sour environments even at high temperatures in deep wells. The alloy is also used for tubing and a variety of other downhole and surface components.
Hastelloy C 276 undergoes heat treatment processes, such as the hot working heat process or cold working heat treatment process. After that, C 276 undergoes solid solution annealing and is rapidly cooled by water quenching.
Hastelloy or UNS N10276 is known for their good weldability. It can be referred to as the ability of a material to be welded and to perform satisfactorily in the imposed service environment. The welded component should be given the utmost importance when determining a suitable weld process or procedure. If proper welding techniques and procedures are followed, high-quality welds can be produced with conventional arc welding processes.
Hastelloy C-276 with its high corrosion resistance and good welding properties makes it an ideal alloy when it comes to application. It is mainly used in an industry setting pertaining to pollution control treatments, chemical processing plants, waste treatment plants, marine engineering and pulp and paper production etc.