Views: 27 Author: Shirley Publish Time: 2025-07-30 Origin: Site
Hastelloy C276 (UNS N10276, W.Nr 2.4819) is the most widely used nickel-chromium-molybdenum-tungsten alloy in aggressive chemical service. In plain terms, it is the stainless steel you reach for when ordinary grades fail: it shrugs off hydrochloric, sulfuric and phosphoric acids, resists pitting and crevice corrosion in chlorides, and keeps its strength at high temperature. This page is a quick-start introduction - what C276 is made of, how it performs, what standards cover it, and what forms you can buy it in. For the full treatment, start at the complete Hastelloy C276 guide and follow the links from there.
Hastelloy C276 is a nickel alloy built for two jobs: surviving non-oxidizing (reducing) acids like hydrochloric and sulfuric, and resisting chloride pitting and stress-corrosion cracking. Its secret is 15-17% molybdenum plus 3-4.5% tungsten on a nickel base with just enough chromium to handle oxidizing contaminants. It costs several times stainless steel, but it lasts where stainless steel cannot.
Hastelloy C276 is a corrosion-resistant nickel alloy. Think of it as a tougher, more acid-resistant cousin of stainless steel: where 316L would pit or dissolve, C276 keeps working - which is why chemical plants, pollution-control scrubbers and offshore equipment pay a premium for it.
The name comes from its family. "Hastelloy" is the Haynes International brand for a series of corrosion-resistant nickel alloys, and "C" marks the chromium-bearing group built for oxidizing-plus-reducing mixed acid service. C276 is the workhorse of that group. It is formally designated UNS N10276 in the American system and W.Nr 2.4819 in the German system, and it has been the default material for hydrochloric acid and flue-gas-desulfurization service since the early 1970s.
What makes it special is not one element but a balance. The nickel base resists chloride stress-corrosion cracking, the molybdenum and tungsten resist reducing acids, and the chromium handles oxidizing conditions and maintains pitting resistance. Almost no alloy else combines all three, which is why C276 shows up again and again in the hardest chemical environments. If you are entirely new to nickel alloys, the what is Hastelloy C276 page gives the slower, first-principles version.
C276 is roughly 57% nickel with about 15.5% chromium, 16% molybdenum, 3.75% tungsten and 6% iron. The nickel is the balance of the alloy - the part left over after the other elements are counted - not a fixed number.
Chemical composition of Hastelloy C276 (UNS N10276), nominal wt% and the role of each element
| Element | Typical wt% | Specification range | What it does |
|---|---|---|---|
| Nickel (Ni) | about 57% | Balance | The base metal: ductility, toughness and resistance to chloride stress-corrosion cracking |
| Chromium (Cr) | 15.5% | 14.5-16.5% | Resists oxidizing acids (nitric, chromic) and supports pitting resistance |
| Molybdenum (Mo) | 16% | 15-17% | The key element against reducing acids (HCl, H2SO4, H3PO4) and localized corrosion |
| Tungsten (W) | 3.75% | 3-4.5% | Works with molybdenum to broaden reducing-acid resistance |
| Iron (Fe) | 6% | 4-7% | Stabilizes the microstructure and controls cost |
| Cobalt (Co) | 1.5% | 2.5% max | Trace impurity, kept low because it can lower corrosion resistance |
| Manganese (Mn) | 0.5% | 1.0% max | Deoxidizer; aids hot workability |
| Vanadium (V) | 0.1% | 0.35% max | Trace element, kept low |
| Silicon (Si) | 0.05% | 0.08% max | Deoxidizer; higher levels cause embrittlement |
| Carbon (C) | 0.005% | 0.01% max | Kept ultra-low to prevent weld sensitization |
| Phosphorus (P) | - | 0.04% max | Impurity; excess promotes hot cracking |
| Sulfur (S) | - | 0.03% max | Impurity; excess causes hot shortness |
| Copper (Cu) | - | 0.5% max | Residual, not a defining element |
| Titanium (Ti) | - | 0.7% max | Residual, not a defining element |
Data note: the previous version of this page listed nickel as "52%" and copper and titanium as "Remain". That was misleading. Under ASTM B574/B575 the nickel content of N10276 is the balance - the remainder after all other specified elements - and lands at roughly 57% on typical heats. Copper and titanium are trace residuals capped at 0.5% and 0.7%, not defining additions. The table above reflects the specification. For a heat-by-heat breakdown see Hastelloy C276 chemical composition.
C276 is dense (8.89 g/cm3), stiff (about 205 GPa), and thermally stable up to high temperature. Its thermal expansion is close to stainless steel, and it holds useful strength well above room temperature.
Physical properties of Hastelloy C276 at room temperature unless noted
| Property | Value | Engineering meaning |
|---|---|---|
| Density | 8.89 g/cm3 (0.321 lb/in3) | About 13% heavier than 316L - account for it in weight and support design |
| Melting range | 1323-1371 deg C (2413-2500 deg F) | High melting point allows high-temperature use |
| Specific heat | 427 J/kg.K at 20 deg C | Standard for nickel alloys; drives heat-up and cool-down rates |
| Thermal conductivity | 10.1 W/m.K at 20 deg C | Low, like stainless - expect heat to spread slowly |
| Mean thermal expansion | 11.2 um/m.deg C (20-100 deg C) | Close to stainless; eases C276-to-steel joints |
| Electrical resistivity | 1.30 uOhm.m at 20 deg C | Relevant for resistance-heating and instrument applications |
| Modulus of elasticity | about 205 GPa | Stiffness between steel and titanium; design for deflection |
| Magnetic permeability | Low (austenitic) | Essentially non-magnetic in the annealed condition |
Two numbers matter most in practice. The density means a C276 vessel or line weighs noticeably more than the same part in stainless, which feeds into lifting, support and transport cost. The elastic modulus of about 205 GPa is lower than carbon steel's 207 GPa and much lower than tungsten's, so long thin sections deflect more and should be checked for stiffness, not just strength.
Solution-annealed C276 meets 283 MPa (41 ksi) minimum yield strength and 690 MPa (100 ksi) minimum tensile strength with at least 40% elongation. It is strong, formable, and keeps useful strength at elevated temperature.
Mechanical properties of solution-annealed Hastelloy C276 (ASTM B574/B575 minimum)
| Property | Minimum | Typical | What it means |
|---|---|---|---|
| Tensile strength | 690 MPa (100 ksi) | 760 MPa (110 ksi) | High ultimate strength gives a generous safety margin |
| Yield strength (0.2% offset) | 283 MPa (41 ksi) | 320 MPa (46 ksi) | Moderate yield - design for it rather than tensile |
| Elongation | 40% | 50% | Excellent ductility for forming complex shapes |
| Reduction of area | 60% | 65% | High, indicating sound, tough material |
| Hardness | - | under 210 HB / 90 HRB | Soft enough to machine; work-hardens moderately |
| Elevated-temperature yield | - | about 240 MPa at moderate temperature | Retains useful strength well above room temperature |
Two things to note. First, yield strength is moderate rather than outstanding - duplex stainless steels beat it - so high-pressure service needs either a heavier wall or a stronger supporting structure. Second, the 40% elongation is what lets fabricators cold-form and cold-work C276 into complex components without cracking. The full property set, including the effect of temperature, is in Hastelloy C276 mechanical properties.
C276 resists both kinds of acid attack - oxidizing and reducing - plus chloride pitting, crevice corrosion and stress-corrosion cracking. The reason is the molybdenum-tungsten-chromium balance on a nickel base.
Corrosion resistance in C276 is not a single mechanism but three stacked ones. The molybdenum and tungsten resist reducing acids such as hydrochloric, sulfuric and phosphoric. The chromium handles oxidizing media such as nitric acid, hypochlorites and wet chlorine, and it also feeds the passive film that resists pitting. The nickel base itself resists chloride stress-corrosion cracking, which is the failure mode that breaks ordinary stainless steels in seawater and chloride condensate.
This is why C276 earns its price. A 316L stainless in hot chloride or reducing acid either pits or stress-cracks; C276 in the same service keeps going. The measured evidence is in the corrosion tables - C276 shows rates under 0.13 mm/y (5 mpy) in most aggressive media, the threshold industry treats as acceptable. For the medium-by-medium breakdown, read Hastelloy C276 corrosion resistance.
Corrosion resistance of C276 across common environments
| Environment | C276 performance | Notes |
|---|---|---|
| Hydrochloric acid | Excellent up to ~60 deg C | All concentrations; the default HCl alloy - see the HCl guide |
| Sulfuric acid | Excellent across wide range | Strong in most concentrations and temperatures |
| Phosphoric acid | Excellent | Standard material for wet-process phosphoric acid |
| Nitric acid (oxidizing) | Good | Chromium provides oxidizing resistance |
| Seawater and chlorides | Excellent | Resists pitting, crevice corrosion and chloride SCC |
| Flue-gas desulfurization | Excellent | Handles chlorides, fluorides and acid condensate |
| Stress-corrosion cracking | Essentially immune | Nickel base resists chloride SCC |
One honest caveat: C276 is not universal. In strongly oxidizing, chromium-hungry environments it gives ground to its sister alloy Hastelloy C22, and in very pure reducing acids the Hastelloy B3 alloy can be stronger. Selection is always duty-specific, which is exactly what the comparison pages are for.
C276 is covered by a family of ASTM specifications - B574 for bar and rod, B575 for plate, sheet and strip, B619 and B626 for welded pipe and tube, B622 for seamless, B366 for welding fittings and B564 for forgings - with ASME SB- equivalents for code-stamped equipment.
ASTM and ASME standards for Hastelloy C276 by product form
| Product form | ASTM | ASME | What it covers |
|---|---|---|---|
| Plate, sheet and strip | B575 | SB-575 | Low-carbon Ni-Mo-Cr-W alloy plate, sheet and strip |
| Bar, rod and wire | B574 | SB-574 | Low-carbon Ni-Mo-Cr-W alloy rod and bar |
| Seamless pipe and tube | B622 | SB-622 | Seamless nickel and nickel-alloy pipe and tube |
| Welded pipe | B619 | SB-619 | Welded nickel and nickel-alloy pipe |
| Welded tube | B626 | SB-626 | Welded nickel and nickel-alloy tube |
| Welding fittings | B366 | SB-366 | Factory-made wrought nickel-alloy welding fittings |
| Forged fittings | B462 | SB-462 | Wrought UNS N10276 forged fittings |
| Forgings (incl. flanges) | B564 | SB-564 | Nickel-alloy forgings |
Data note: the previous version of this page listed ASTM B575 as "Seamless Fittings" and repeated B574 twice. That was wrong. B575 is plate, sheet and strip; seamless and welded pipe are B622 and B619 respectively; fittings are B366 (welding) and B462/B564 (forged). The table above is the correct mapping. Beyond ASTM, C276 also appears in EN and DIN (DIN 17744/17750 series) and is listed for sour service under NACE MR0175 / ISO 15156. See ASTM standards for Hastelloy C276 for the full map, and equivalent grades of Hastelloy C276 for the international cross-reference.
C276 comes in every wrought form - bar, plate, sheet, pipe, tube, fittings, flanges, forgings and wire - each made to its own ASTM specification and supplied in the solution-annealed condition.
Hastelloy C276 product forms and typical applications
| Product form | Typical use | Related page |
|---|---|---|
| Bar (round, hex, square) | Shafts, valves, pumps, fasteners, machined parts | C276 bars |
| Plate and sheet | Tanks, vessels, heat exchangers, scrubbers, liners | C276 plate guide |
| Seamless pipe and tube | High-pressure, high-temperature corrosive fluid lines | Hastelloy steel pipe |
| Welded pipe and tube | Economical large-diameter lines at moderate pressure | Hastelloy steel pipe |
| Fittings (elbows, tees, reducers) | Corrosion-resistant piping systems | C276 pipe fittings |
| Flanges | Connecting piping and equipment to B16.5/B16.47 | C276 flange guide |
| Forgings | Critical components needing grain-structure integrity | Nickel alloy forgings |
| Fasteners | Bolts, studs, nuts in corrosive bolted joints | Nickel alloy fasteners |
| Wire | Electrodes, filler wire, springs | Hastelloy welding wire |
Whatever the form, one procurement rule holds: specify the solution-annealed condition. Some suppliers offer as-rolled or as-welded C276 at a discount, and it is unsuitable for corrosive service because the weld heat-affected zone is sensitized. Always write "solution annealed" into the purchase order and require a mill test report. Browse the range from the Hastelloy C276 product page.
C22 has more chromium (20-22.5% vs 14.5-16.5%) and less molybdenum (12.5-14.5% vs 15-17%), which makes it the stronger alloy in oxidizing environments and the more weldable one, while C276 is the stronger and cheaper choice in reducing acids.
Hastelloy C276 vs C22 - the key differences at a glance
| Attribute | C276 (N10276) | C22 (N06022) | Winner |
|---|---|---|---|
| Chromium | 14.5-16.5% | 20-22.5% | C22 - better oxidizing resistance |
| Molybdenum | 15-17% | 12.5-14.5% | C276 - better reducing-acid resistance |
| Tungsten | 3-4.5% | 2.5-3.5% | C276 - more localized-corrosion support |
| PREN (nominal) | about 68-73 | about 72 | C22 - slightly higher |
| Oxidizing environments | Good | Superior | C22 |
| Reducing acids (HCl, H2SO4) | Superior | Good | C276 |
| Weldability | Good (needs care) | Easier | C22 |
| Cost | Lower | Higher (more Cr) | C276 |
The choice reduces to the environment. If the stream is oxidizing - nitric acid, ferric-bearing solutions, wet chlorine - pick C22. If it is reducing - hydrochloric or sulfuric acid - C276 is the better value. Many real chemical streams swing between the two, which is why C22 is often called the more versatile alloy. For the head-to-head treatment see Hastelloy C22 vs C276: key differences and selection guide and the shorter difference between Hastelloy C22 and C276.
C276 is used wherever corrosion failure is not an option: chemical processing, flue-gas desulfurization, pulp and paper, pollution control, marine engineering, and oil and gas sour service.
Chemical processing - reactors, heat exchangers, columns and piping in acid service; see Hastelloy C276 for chemical plants.
Flue-gas desulfurization - scrubbers, ducting and dampers handling acid condensate; see Hastelloy C276 for FGD systems.
Pulp and paper - bleach-plant and digester equipment; see Hastelloy C276 for the pulp and paper industry.
Pollution control - hazardous-waste incineration and effluent treatment.
Marine and offshore - seawater-cooled and chloride-bearing equipment.
Oil and gas - sour service, downhole and processing equipment.
Pharmaceutical and food - high-purity corrosion-resistant equipment.
The common thread is chloride plus acid. Wherever those two are present together, ordinary stainless fails and C276 becomes the economical answer. The umbrella page Hastelloy C276 applications maps the full list by industry.
Buy C276 by naming the ASTM specification and product form, requiring the solution-annealed condition, and insisting on a mill test report that shows the actual chemistry, mechanical properties and heat treatment. Five steps cover it.
Define the duty. Write down the chemicals, concentrations, temperatures, pressures and whether chlorides or oxidizing species are present. That single paragraph decides whether C276 is even the right alloy, before any money is spent.
Pick the ASTM specification per form. Bar to B574, plate and sheet to B575, seamless pipe and tube to B622, welded pipe to B619, welded tube to B626, welding fittings to B366, forged fittings to B462, forgings and flanges to B564. Use the ASME SB- equivalents for code-stamped equipment. See ASTM standards for Hastelloy C276.
Require the solution-annealed condition. State that material shall be solution-annealed and quenched, and that a certified heat-treatment record is required. As-rolled or as-welded material is unacceptable for corrosive service.
Demand a complete mill test report. The MTR must show actual chemistry, mechanical test results, the annealing temperature and the quench method - not just a conformity statement. Traceability to the heat number is non-negotiable.
Specify the inspection and documentation package. For forgings, require ultrasonic and liquid-penetrant examination to the applicable standards. For sour service, add the NACE MR0175 / ISO 15156 hardness requirement. Keep every certificate with the equipment.
What is Hastelloy C276 used for?
C276 is used wherever corrosion failure is unacceptable: chemical processing in reducing acids, flue-gas desulfurization scrubbers, pulp and paper bleach plants, pollution-control equipment, marine and offshore chloride service, and oil and gas sour service. It is the default material for hydrochloric acid handling.
What is the difference between Hastelloy C276 and C22?
C22 has more chromium (20-22.5% versus 14.5-16.5%) and less molybdenum (12.5-14.5% versus 15-17%). C22 is stronger in oxidizing environments and is easier to weld; C276 is stronger and cheaper in reducing acids such as hydrochloric and sulfuric acid.
Is Hastelloy C276 magnetic?
No. In the solution-annealed condition C276 is austenitic and essentially non-magnetic. It is widely used where non-magnetic properties are required, such as some instrument and marine applications.
What is the melting point of Hastelloy C276?
The melting range is 1323 to 1371 deg C (2413 to 2500 deg F). This high melting range is part of why the alloy retains useful strength and corrosion resistance at elevated temperature.
What is the density of Hastelloy C276?
8.89 g/cm3 (0.321 lb/in3). It is about 13% heavier than 316L stainless steel, so account for the extra weight in lifting, support and transport design.
What is the PREN of Hastelloy C276?
About 68, often rounded to 69, calculated as percent chromium plus 3.3 times percent molybdenum plus 16 times percent nitrogen. PREN measures chloride pitting resistance, not acid resistance.
Is Hastelloy C276 resistant to hydrochloric acid?
Yes, and it is the default alloy for it. C276 resists hydrochloric acid at all concentrations up to about 60 deg C, with corrosion rates under 0.13 mm/y. Boiling or near-boiling HCl needs C22, Alloy 59, zirconium or tantalum instead.
What is the tensile strength of Hastelloy C276?
690 MPa (100 ksi) minimum in the solution-annealed condition, with typical values around 760 MPa (110 ksi). Yield strength is 283 MPa (41 ksi) minimum.
What ASTM specification covers Hastelloy C276 plate?
ASTM B575 (ASME SB-575) covers plate, sheet and strip. Bar and rod are B574, seamless pipe and tube are B622, welded pipe is B619, welded tube is B626, welding fittings are B366 and forgings are B564.
Does Hastelloy C276 need to be solution annealed?
Yes, for corrosive service. Solution annealing dissolves harmful intermetallic and carbide phases and restores uniform corrosion resistance. As-rolled or as-welded material has a sensitized heat-affected zone and is unsuitable for aggressive environments.
Is Hastelloy C276 better than 316L stainless steel?
For corrosion, overwhelmingly yes in chlorides and reducing acids. 316L pits and stress-cracks in hot chloride and dissolves in hydrochloric acid, where C276 keeps working. The trade-off is cost: C276 is several times more expensive, so 316L remains the right choice where it is adequate.
Can Hastelloy C276 be welded?
Yes, readily, with matching filler metal such as ERNiCrMo-4 (GTAW/GMAW) or ENiCrMo-4 (SMAW). It needs more careful heat management than C22 because of its higher tungsten and iron, and welded components for corrosive service should be solution-annealed afterward.
What is the UNS number for Hastelloy C276?
UNS N10276. The German Werkstoff number is W.Nr 2.4819. These are the standard identifiers used on mill test reports and purchase orders.
How much does Hastelloy C276 cost compared to stainless steel?
C276 typically costs several times the price of 316L, driven by its high nickel and molybdenum content. It is cheaper than C22 and Alloy 59. The lifecycle cost, however, is usually far lower than stainless in the aggressive service where C276 is specified.
Where does Hastelloy C276 come from?
C276 was developed by Haynes International and has been in service since the early 1970s. It is now produced by several mills worldwide and supplied by distributors and manufacturers such as JN Alloy in the full range of product forms.
What is the difference between Hastelloy C276 and Inconel 625?
Both are nickel alloys, but C276 has more molybdenum and tungsten and less chromium, making it the stronger choice in reducing acids. Inconel 625 has more chromium and niobium, making it stronger at high temperature and the better choice for some oxidizing and high-temperature service. See the C276 vs Inconel 625 comparison for the full picture.
Is Hastelloy C276 suitable for sour service?
Yes. C276 is listed in NACE MR0175 / ISO 15156 for sour (H2S) service in the solution-annealed condition and within the specified hardness ceiling, which matters for oil and gas applications.
What temperatures can Hastelloy C276 withstand?
C276 retains useful strength well above room temperature and resists oxidation at elevated temperature. Its practical service limits depend on the environment - in hydrochloric acid the ceiling is about 60 deg C, while in oxidizing service it can run much hotter. See the C276 temperature-limits page for the full envelope.
