Chemical composition

Phosphorus and sulphur limits as given in the standards.

The table includes Hastelloy C22 for comparison. In C276, molybdenum and tungsten give resistance to reducing acids and localised corrosion; chromium gives resistance to oxidising media.

Mechanical properties

Values for solution-annealed material as given in ASTM B575.

C276 is supplied solution annealed and rapidly cooled. It keeps good strength and ductility over a wide temperature range, and is used for pressure parts up to about 675 °C under ASME design rules, although it is chosen mainly for corrosion resistance rather than heat resistance.

Equivalent grades and physical properties

Equivalent designations are similar but not identical; order to the standard you need.

Typical values from recognised industry references, for guidance only; they are not specification limits.

See the full grade equivalent chart for other grades.

Corrosion resistance

Hastelloy C276 resists a remarkably wide range of chemical environments: hydrochloric and sulphuric acids, hot contaminated mineral acids, organic acids, wet chlorine gas, hypochlorite and chlorine dioxide solutions, ferric and cupric chlorides, seawater and brines, and sour gas. With a pitting resistance equivalent number of about 65–70, it resists pitting and crevice corrosion in hot chloride solutions where stainless steels and lower nickel alloys fail, and its high nickel and molybdenum make it resistant to chloride stress corrosion cracking.

Its limits are hot, strongly oxidising acids such as concentrated nitric acid, where higher-chromium alloys perform better, and long exposure between about 650 °C and 1040 °C, which can form precipitates that reduce corrosion resistance and toughness.

Hastelloy C276 products we supply

• Pipes and tubes – seamless to ASTM B622, welded to B619 and B626.
• Plates and sheets – ASTM B575; see Hastelloy C276 sheets and plates.
• Round bars – ASTM B574.
• Flanges and forged fittings – ASTM B564.
• Butt-weld fittings – ASTM B366 WPHC276.
• Fasteners – from B574 bar; welding wire ERNiCrMo-4.

All Hastelloy alloys are on the Hastelloy page.

Comparable alloys

Hastelloy C22 has more chromium and less molybdenum, giving better resistance to oxidising media and to processes that alternate between oxidising and reducing conditions. Inconel 625 is stronger and suits oxidising and seawater service, but is less resistant to strongly reducing acids. Hastelloy B-2 and B-3 resist hydrochloric acid even better than C276 but fail in the presence of oxidising contaminants. Incoloy 825 and SS 904L are lower-cost options for milder conditions.

Typical applications of Hastelloy C276

Hastelloy C276 is used for flue-gas desulphurisation scrubbers, ducts, dampers and stack liners, pulp and paper bleach plants, chemical and pharmaceutical reactors, heat exchangers, evaporators and transfer piping, chlorination systems, sulphuric acid plants, pickling equipment, waste incineration and treatment, sour gas production equipment and downhole components, and seawater and brine service where other alloys would pit.

Fabrication

Hastelloy C276 is welded by TIG, MIG and manual arc processes using matching ERNiCrMo-4 filler or matching electrodes, with low heat input and interpass temperatures kept low to limit the time in the precipitation range. Joints must be clean and free of contaminants. Because of its low carbon and silicon, C276 can be used as welded for most corrosive service, without post-weld heat treatment. It work-hardens quickly in forming and machining; rigid tooling and sharp carbide tools are needed.