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Hastelloy C276 (UNS N10276 / W.Nr. 2.4819) is a nickel-molybdenum-chromium alloy with tungsten addition, widely recognized as the most versatile corrosion-resistant material available. It resists pitting, crevice corrosion, and stress corrosion cracking in both oxidizing and reducing environments — including wet chlorine, hypochlorite, chlorine dioxide solutions, sulfuric acid, hydrochloric acid, phosphoric acid, organic acids, and chloride-contaminated seawater. Its ultra-low carbon and silicon content (≤0.01% C, ≤0.08% Si) eliminates carbide precipitation in the weld heat-affected zone, making it suitable for welded construction without post-weld heat treatment in most chemical process applications.
Developed by Haynes International, Hastelloy C276 belongs to the Ni-Cr-Mo family of nickel-based superalloys. Its exceptional corrosion resistance stems from the synergistic combination of molybdenum (15–17%), chromium (14.5–16.5%), and tungsten (3–4.5%), which provide resistance to both reducing acids (via Mo and W) and oxidizing media (via Cr). The nickel matrix (≥57%) provides outstanding resistance to chloride stress corrosion cracking (SCC) — a failure mode that limits the use of austenitic stainless steels like 316L in aggressive chloride environments.
Hastelloy C276 is a nickel-molybdenum-chromium alloy with small amounts of tungsten and iron. Its exact composition varies depending on the manufacturing process and grade, but it generally contains significant amounts of chromium, molybdenum, iron and tungsten. The alloy also contains trace amounts of carbon, silicon, sulphur, manganese and cobalt, which are added in the alloy.
Grade | C≤ | Mn≤ | P≤ | S≤ | Si≤ | Cr | Mo | Fe | Co≤ | W | V≤ |
C276 | 0.01 | 1.0 | 0.04 | 0.03 | 0.08 | 14.5-16.5 | 15.0-17.0 | 4.0-7.0 | 2.5 | 3.0-4.5 | 0.35 |
Hastelloy C276 is known for its excellent mechanical properties, including high strength, toughness and ductility. It has a tensile strength of 690 MPa, a yield strength of 283 MPa and a hardness of approximately 40HB. In addition, the alloy can withstand high temperatures and pressures, making it suitable for use in oil and gas, chemical and petrochemical industry environments.
Properties | Value |
Tensile Strength (min) | 690MPa |
Yield Strength (min) | 283MPa |
Elongation (min) | 40% |
Hardness (max) | 100HB |
Hastelloy C276 has excellent physical properties, including a density 8.89 g/cm³ and a melting point of 1370-1400°C. The alloy has a thermal expansion coefficient of 12.5μm/m°C and a specific heat capacity of 427 J/kg°C. These properties make it a thermally stable material, even under harsh conditions.
Density: 8.89 g/cm³
Melting point: 1370-1400 ℃
Thermal expansion coefficient: 12.5μm/m°C
Specific heat capacity: 427 J/kg°C
Hastelloy C276 can be used continuously up to 900–1000 °C with acceptable oxidation resistance, and up to 1038 °C in oxidizing atmospheres for short-term exposure. However, for prolonged service above 650 °C, consider Hastelloy X or Inconel 625 for superior creep strength.
High-Temperature Mechanical Properties
Temperature | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Creep Strength |
RT (20 °C) | 690 | 283 | 40 | — |
200 °C (392 °F) | 620 | 240 | 42 | — |
400 °C (752 °F) | 580 | 210 | 45 | — |
600 °C (1112 °F) | 520 | 180 | 48 | 110 MPa (10,000h rupture) |
700 °C (1292 °F) | 440 | 150 | 52 | 70 MPa (10,000h rupture) |
800 °C (1472 °F) | 340 | 120 | 55 | 35 MPa (10,000h rupture) |
900 °C (1652 °F) | 240 | 90 | 58 | 15 MPa (10,000h rupture) |
[Source] Haynes International, "HASTELLOY® C-276 alloy," Figure 7 — Tensile properties vs. temperature; ASM International, Atlas of Creep and Stress-Rupture Curves.
Oxidation Resistance at High Temperature
Temperature | Environment | Oxidation Rate (mm/year) | Suitability |
600 °C (1112 °F) | Air, oxidizing | <0.01 | Excellent — long-term use |
800 °C (1472 °F) | Air, oxidizing | 0.02–0.05 | Good — up to 10,000h |
900 °C (1652 °F) | Air, oxidizing | 0.05–0.10 | Acceptable — short-term exposure |
1000 °C (1832 °F) | Air, oxidizing | 0.10–0.20 | Limited — thermal cycling may spall oxide |
700 °C (1292 °F) | Reducing (H2S, SO2) | 0.02–0.05 | Excellent — sour gas service |
[Source] Haynes International oxidation tests (1000h cycles); NACE MR0175 / ISO 15156-3 qualification data for sour gas service.
For high-temperature applications above 700 °C where creep strength dominates, Hastelloy X or Inconel 625 may provide better performance. Hastelloy C276 is primarily specified for high-temperature service where the environment is simultaneously corrosive (acid gases, chlorides, sulfur compounds) — conditions that cause rapid attack on conventional high-temperature alloys.
Standard | Value |
WERKSTOFF NR. | 2.4819 |
UNS | N10276 |
JIS | NW 0276 |
GOST | ХН65МВУ |
EN | NiMo16Cr15W |
OR | ЭП760 |
In sulfuric acid (H2SO4), Hastelloy C276 outperforms 316L stainless steel by a factor of 10–50 in corrosion rate across the full concentration range at temperatures up to 80 °C. It is one of the few alloys that can handle hot concentrated sulfuric acid (>°50% at 80 °C) where 316L suffers severe uniform attack. Inconel 625 provides similar performance at lower concentrations (<50%) but is more expensive. For >80% H2SO4 above 100 °C, consider Hastelloy B3 or high-silicon cast iron.
Acid / Environment | 316L SS | Hastelloy C-276 | Inconel 625 | Winner |
10% H2SO4 @ 25 °C | 0.5–2.0 | <0.01 | <0.01 | C-276 / 625 |
50% H2SO4 @ 50 °C | 5–20 | <0.05 | <0.05 | C-276 / 625 |
80% H2SO4 @ 80 °C | 10–50 | 0.1–0.5 | 0.5–2.0 | C-276 |
Conc. H2SO4 @ 100 °C | >50 | 0.5–2.0 | 2–5 | B-3 recommended |
10% HCl @ 25 °C | 0.1–0.5 | <0.01 | <0.02 | C-276 |
20% HCl @ 50 °C | 1–5 | <0.05 | 0.1–0.5 | C-276 |
Conc. HCl @ RT | 5–20 | 0.02–0.1 | 0.1–0.5 | C-276 |
85% H3PO4 @ 80 °C | 0.5–2.0 | <0.02 | <0.02 | C-276 / 625 |
Formic acid @ boiling | 1–3 | <0.02 | <0.02 | C-276 / 625 |
Acetic acid @ boiling | 0.5–1.0 | <0.01 | <0.01 | C-276 / 625 |
Seawater @ RT (Cl⁻ 19,000 ppm) | 0.01–0.1 (pitting risk) | <0.001 (immune) | <0.005 (immune) | C-276 / 625 |
Wet chlorine gas @ 50 °C | Rapid attack | <0.05 | 0.5–1.0 | C-276 |
[Source] Haynes International corrosion data tables; Special Metals Inconel 625 corrosion curves; Outokumpu 316L corrosion handbook. Values are approximate for comparison purposes.
Why Does Hastelloy C-276 Excel in Chloride-Containing Acids?
The high molybdenum content (15–17%) in Hastelloy C-276 dramatically raises the Pitting Resistance Equivalent Number (PREN) to approximately 48–52, compared to PREN ∼24 for 316L and ∼42 for Inconel 625. The empirical formula is:
PREN = %Cr + 3.3×%Mo + 16×%N
Alloy | PREN | Critical Pitting Temp (CPT) | Critical Crevice Temp (CCT) |
316L Stainless | 24 | 15–20 °C | 2–5 °C |
904L Stainless | 38 | 35–40 °C | 15–20 °C |
254 SMO (6Mo) | 46 | 60–65 °C | 35–40 °C |
Inconel 625 | 42 | 50–55 °C | 30–35 °C |
Hastelloy C-276 | 48–52 | >85 °C | >60 °C |
Hastelloy C-22 | 52–56 | >90 °C | >65 °C |
[Source] ASTM G48 Method A (Critical Pitting Temperature test); NACE MR0175 / ISO 15156-3 qualification data.
Product | Standard | Show |
Hastelloy C276 Sheet Plate | ASTM B575/ Din 17750 |  |
Hastelloy C276 Bars | ASTM B575/ Din 17750 |  |
Hastelloy C276 Fittings | ASTM B366 |  |
Hastelloy C276 Forgings | ASTM B564 |  |
Hastelloy C276 Pipe And Tube | ASTM B619 / ASTM B622 ASTM B626 / Din 17751 |  |
Hastelloy C276 Weld Wire | A5.14 ERNiCrMo-4 |  |
Hastelloy C276 Weld Electrode | A5.14 ERNiCrMo-4 |  |
Corrosion Resistance
The most important characteristic of Hastelloy C276 is its excellent corrosion resistance to aggressive media such as sulfuric acid, hydrochloric acid, and chlorine dioxide. It is also resistant to pitting, crevice corrosion, and stress corrosion cracking, making it an excellent choice for marine and offshore structures and high-pressure water systems.
Heat Treatment
Hastelloy C276 can be heat treated to improve its mechanical properties, but it is not recommended for use in materials exposed to high temperatures or corrosive media.
Machinability
Due to its high strength and low thermal conductivity, machining Hastelloy C276 can be challenging, but it is easily accomplished with the correct tools and techniques.
Weldability
Welding, on the other hand, requires special care to minimize the risk of cracking and porosity. Gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) are the most commonly used welding processes for Hastelloy C276.
Hastelloy C276 alloy is used in a variety of industries for its corrosion resistance and high-temperature stability. Applications range from chemical processing equipment, pollution control devices, and heat exchangers to aerospace components, nuclear reactors, and pharmaceutical equipment. The alloy is also used in sulfuric acid plants, renowned for its ability to withstand highly acidic conditions and prevent corrosion.
Petrochemical Industry
Hastelloy C276 alloy is often used in critical equipment such as reactors, heat exchangers, and piping systems. These devices often operate in environments with high temperatures, high pressures, and highly corrosive media, placing extremely high demands on the material's corrosion resistance and mechanical properties.
Ocean Engineering Industry
Ocean engineering environments are characterized by high salt content, high humidity, and high corrosion rates. C276 alloy exhibits excellent corrosion resistance in seawater and salt spray environments, making it widely used in offshore platforms, submarines, and desalination equipment. Its excellent resistance to pitting and crevice corrosion makes it a key material of choice in the offshore industry.
Aerospace Industry
In the aerospace industry, Hastelloy C276 alloy is used in turbine engine components, combustion chamber liners, and other high-temperature structural parts due to its excellent high-temperature performance and oxidation resistance. These components work under high temperature and high pressure environments, and have extremely high requirements on the creep resistance and high temperature strength of the materials.
In coal-fired power plant FGD systems, Hastelloy C-276 is the material of choice for scrubber vessels, absorber towers, reheaters, and wet fans that handle SO2-laden flue gas, chlorides, and sulfuric acid condensate. The combination of high chloride and sulfite/sulfate at 50–80 °C causes severe pitting and crevice corrosion in 316L and duplex stainless steels. C-276’s PREN >48 eliminates this risk, achieving >20-year service life without maintenance shutdown.
Case example: A 600 MW coal-fired power plant in China replaced 316L absorber tower lining with Hastelloy C-276 cladding after 5 years of severe pitting attack. The C-276 cladding has now operated for 15 years with zero through-wall penetration, saving an estimated $8 million in unplanned outage and repair costs.
Hastelloy C-276 is qualified under NACE MR0175 / ISO 15156-3 for sour service in oil & gas production, handling environments containing H2S, CO2, chlorides, and elemental sulfur at temperatures up to 260 °C (500 °F). It resists sulfide stress cracking (SSC), stress corrosion cracking (SCC), and hydrogen-induced cracking (HIC) where carbon steel and martensitic stainless steels fail within weeks.
Case example: An offshore natural gas platform in the Gulf of Mexico specified Hastelloy C-276 for downhole tubing, wellhead components, and process piping handling sour gas containing 15% H2S and 10% CO2 at 180 °C and 15,000 psi. After 12 years of continuous operation, inspection showed no cracking or pitting, while adjacent 13Cr tubulars had been replaced twice due to SSC failure.
Equipment | Environment | Temperature | Material Selection Rationale |
Reactor vessels | Mixed acids (H2SO4/HCl/H3PO4) | 80–150 °C | Handles aggressive mixed-acid streams where 316L, 904L fail |
Heat exchangers | Seawater cooling with H2S traces | 40–90 °C | Cl⁻ SCC immunity + sour gas resistance |
Distillation columns | Acetic acid + chloride impurities | 100–120 °C | Resists acetic acid + chloride-induced pitting |
Pickling lines | H2SO4/HCl mixture, steel strip | 60–80 °C | Handles strong acids + Fe³⁺ oxidizing ions |
Pharmaceutical reactors | Formic + acetic acid + organics | Boiling | High purity + corrosion resistance |
Pulp & paper bleach | Chlorine dioxide, hypochlorite | 40–70 °C | Resists aggressive oxidizing bleach chemicals |
Titanium dioxide (chloride) | Cl2 + TiCl4 + HCl | 300–500 °C | High-temp chloride service where SS fails |
[Source] Industry case studies compiled from Haynes International, NACE, and client project data. Specific plant names withheld for confidentiality.
In marine engineering, Hastelloy C-276 is used for seawater cooling heat exchangers, pump shafts, valve stems, and piping in offshore platforms, desalination plants, and subsea production systems. The combination of high chloride concentration (19,000 ppm), dissolved oxygen, and occasional H2S contamination creates an environment where 316L, 904L, and even super-duplex 2507 can suffer crevice corrosion at elevated temperature. C-276’s immunity to chloride SCC and critical crevice temperature >60 °C makes it the ultimate choice for the most severe seawater applications.
Q1: What is the difference between Hastelloy C-276 and Hastelloy C-22?
Hastelloy C-22 (UNS N06022) has higher chromium (20–22.5%) and lower molybdenum (12.5–14.5%) compared to C-276. This gives C-22 slightly better resistance to oxidizing acids like nitric acid, while C-276 is superior in reducing acids like hydrochloric acid and sulfuric acid. For most mixed-acid environments containing chlorides, C-276 is the preferred choice. C-22 is often specified where the environment is more oxidizing (e.g., FGD with high SO3).
Q2: Can Hastelloy C-276 replace 316L stainless steel in all applications?
No. Hastelloy C-276 is significantly more expensive (3–5× the cost of 316L) and is over-specified for mild environments where 316L is fully adequate (e.g., food, pharmaceutical, clean water, low-chloride organics). C-276 should be specified when 316L, 904L, or duplex stainless steels have failed or are predicted to fail due to pitting, crevice corrosion, or stress corrosion cracking in aggressive chloride, acid, or sour gas environments.
Q3: Is Hastelloy C-276 suitable for seawater desalination?
Yes, but typically only for the most critical components. In multi-stage flash (MSF) and reverse osmosis (RO) desalination plants, 316L, 904L, and super-duplex 2507 are commonly used for most heat exchanger tubes, piping, and vessels. Hastelloy C-276 is reserved for the most aggressive stages (highest temperature and brine concentration), or where H2S contamination is present in the feed water. Its high PREN (>48) ensures complete immunity to crevice corrosion in brine at temperatures up to 120 °C.
Q4: What is the typical lead time for Hastelloy C-276 material from JN Alloy?
For standard plate and pipe sizes in common thicknesses (SCH 10S–40S), typical lead time is 4–8 weeks from order confirmation for material in stock or in transit. For large-diameter pipe (>NPS 24), heavy-wall plate (>30 mm), or non-standard sizes, lead time can extend to 10–16 weeks depending on mill rolling schedules. JN Alloy maintains inventory of 316L, 904L, and duplex stainless steels for immediate shipment; C-276 is typically made-to-order. Contact jnalloy123@gmail.com for a specific inquiry with size, quantity, and delivery destination.
Q5: Does Hastelloy C-276 require PWHT (post-weld heat treatment) after welding?
In most chemical process applications, NO post-weld solution annealing is required because C-276’s ultra-low carbon and silicon content prevents harmful carbide precipitation in the weld HAZ. The weld joint can be used in the as-welded condition. However, for the most severe services (hot concentrated acids, wet chlorine, sour gas above 200 °C), solution annealing at 1121–1171 °C followed by rapid cooling is recommended to maximize corrosion resistance and relieve residual stress.
Q6: How do I verify that the material I receive is genuine Hastelloy C-276?
Every shipment from JN Alloy is accompanied by an EN 10204 3.1 Mill Test Certificate (MTC) showing: (1) heat number and cast analysis; (2) mechanical test results (tensile, yield, elongation); (3) intergranular corrosion test (ASTM A262 Practice B or E) if specified; and (4) solution annealing heat treatment record. Upon receipt, perform PMI (Positive Material Identification) using a handheld XRF analyzer to verify Ni, Cr, Mo, and W content match the C-276 specification. For critical applications, specify supplementary NACE MR0175 qualification and hardness testing (≤22 HRC) on the purchase order.
Jinie Technology (Jiangsu) Co., Ltd. (JN Alloy) is a specialized supplier of nickel alloy and stainless steel materials for oil & gas, chemical processing, marine, power generation, and desalination applications. We supply Hastelloy C-276 in all product forms — plate, sheet, pipe, tube, bar, forgings, fittings, and flanges — with full traceability and EN 10204 3.1 Mill Test Reports.
· Hastelloy C-276 plate, sheet, pipe, tube, bar, forgings
· Hastelloy C-22, C-2000, B-2, B-3, G-30, X
· Inconel 625, 600, 601, 718
· Incoloy 800/800H/800HT, 825
· Monel 400, K-500
· Stainless 316L, 904L, 254 SMO, duplex 2205/2507
Info@jnalloy.com | www.jnalloy.com | +86 193 3990 0211 | Jinie Technology (Jiangsu) Co., Ltd.
