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UNS N10276 | W.Nr. 2.4819 | ASTM B622 / B564 / B366
Alloy C276, universally known as Hastelloy C-276, is a premier low-carbon nickel-molybdenum-chromium-tungsten wrought alloy. Due to its exceptional resistance to both oxidizing and reducing media, it stands as one of the most widely specified nickel alloys for chemical processing, pollution control, and sour gas service. Its ultra-low carbon content virtually eliminates carbide precipitation during welding, ensuring optimum intergranular corrosion resistance without the need for post-weld heat treatment.
1. Key Properties & Advantages
- Ultra-Low Carbon (≤0.01%) – Effectively prevents post-weld intergranular attack; no PWHT required in most as-welded conditions.
- Universal Corrosion Resistance – Highly resistant to pitting, crevice corrosion, and stress corrosion cracking in chloride-rich media. Exhibits outstanding performance in strong oxidizing acids (e.g., nitric, ferric chloride) and reducing acids (e.g., sulfuric, hydrochloric).
- Excellent Workability – Superior formability, weldability, and machinability compared to many other Ni-Cr-Mo alloys. Readily fabricated by conventional methods.
- Wide-Temperature Stability – Maintains reliable mechanical properties from cryogenic temperatures up to 1000 °C, remaining non-magnetic and highly ductile.
2. Typical Applications
- Chemical Processing – Reactors, heat exchangers, and piping for mixed acid systems, chloride-containing organic processes, and evaporators.
- Flue Gas Desulfurization (FGD) – Scrubbers, dampers, and absorbers handling aggressive acidic condensates.
- Oil & Gas Industry – Sour gas wellhead components, downhole tubing, and offshore platform process piping (meets NACE MR0175 requirements).
- Pharmaceutical & Pulp/Paper – High-purity product vessels, bleaching equipment, and digestors exposed to corrosive chemicals.
- Nuclear & Waste Treatment – Critical components in nuclear fuel reprocessing and hazardous waste neutralization facilities.
3. Applicable Specifications (ASTM / ASME)
Our factory supplies Alloy C276 products fully conforming to the following standards, with full PMI, mechanical, and NDT documentation:
| Product Form | ASTM Standard | ASME Standard |
|---|---|---|
| Seamless Pipe | B622 | SB622 |
| Welded Pipe | B619 | SB619 |
| Heat Exchanger Tube | B626 | SB626 |
| Pipe Fittings (Butt-weld) | B366 | SB366 |
| Forgings & Flanges | B564 | SB564 |
| Round Bar & Wire | B574 | SB574 |
| Plate, Sheet & Strip | B575 | SB575 |
4. Chemical Composition (wt%)
All heats strictly conform to UNS N10276 controls. Ultra-low carbon and silicon ensure top-tier welding and corrosion performance.
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | Balance (≥57.0) |
| Chromium (Cr) | 14.5 – 16.5 |
| Molybdenum (Mo) | 15.0 – 17.0 |
| Tungsten (W) | 3.0 – 4.5 |
| Iron (Fe) | 4.0 – 7.0 |
| Cobalt (Co) | ≤ 2.50 |
| Carbon (C) | ≤ 0.010 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 0.08 |
| Vanadium (V) | ≤ 0.35 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
5. Physical Properties (Typical Values)
| Property | Value | Unit |
|---|---|---|
| Density | 8.89 | g/cm³ |
| Melting Range | 1325 – 1370 | °C |
| Mean CTE (20 – 100 °C) | 11.5 × 10⁻⁶ | /°C |
| Thermal Conductivity (20 °C) | 10.2 | W/(m·K) |
| Modulus of Elasticity | 205 | GPa |
| Electrical Resistivity (20 °C) | 1.30 × 10⁻⁶ | Ω·m |
| Magnetic Property | Non-magnetic | – |
6. Hot Working & Heat Treatment Guidelines
- Hot Working – Forge/start at 1120–1200 °C; finish above 950 °C. Uniform heating and sufficient reduction ratio ensure fine grain structure.
- Solution Annealing – 1120–1170 °C followed by rapid water quench or forced air cooling. Restores full corrosion resistance and ductility.
- Stress Relief (If Absolutely Necessary) – 870–950 °C, hold 1–2 hours, air cool. Not recommended for corrosive service unless solution annealing follows.
- Post-Weld Heat Treatment (PWHT) – Generally unnecessary due to ultra-low carbon. For severely corrosive environments, a full solution anneal at 1120–1170 °C with quench is advised.
⚠️ Critical Warning: Avoid prolonged exposure in the 600–900 °C range. Such service or heat treatment will cause detrimental phase precipitation, severely impairing corrosion resistance.
7. Workability & Fabrication
Machining – Machinable with conventional equipment. Use rigid setups, low cutting speeds, and abundant coolant to counteract work hardening tendencies. Carbide tooling is recommended.
Cold Forming – Excellent ductility permits bending, drawing, and stamping. For heavy deformation, multiple intermediate solution-annealing steps are required to restore ductility.
Welding – Outstanding weldability via GTAW (TIG), GMAW (MIG), and SMAW (stick). Use matching filler metal (e.g., ERNiCrMo-4). No preheat is required, and PWHT is generally unnecessary, maintaining as-welded corrosion resistance.
Hastelloy C276 Elbows
Alloy C276 Stud Bolts, Hex Nuts, and Fasteners
Hastelloy C-276 Nickel Alloy Forging, Uns N10276 Alloy C276 Flange Fitting
C&N UNS N10276 SEAMLESS PIPES
8. Alloy C276 Product Range We Supply
Leveraging our integrated vacuum melting and hot extrusion capabilities, we offer full-scale Alloy C276 pressure components and semi-finished products:
- Seamless Pipes & Heat Exchanger Tubes – Per ASTM B622/B626, custom dimensions, available with EN 10204 3.1 MTC.
- Welded Pipes – ASTM B619, 100% weld X-ray options.
- Butt-Weld Pipe Fittings – Elbows, tees, reducers, caps per ASTM B366, wall thickness SCH10S–SCH80S.
- Forged Flanges & Fittings – WN, SO, BL, SW per ASTM B564, pressure Class 150–2500, RF/RTJ facing.
- Plates, Sheets & Round Bars – Ready for custom machining and vessel fabrication.
All finished products come with full PMI spectral verification, mechanical test reports, and multi-standard NDT (UT/MT/PT). Mill test certificates mutually accepted by global EPC contractors.
For Alloy C276 (UNS N10276 / 2.4819) — the universal corrosion-resistant nickel alloy for mixed acid, sour gas, and FGD service — choose C&N / HONGCHENG. Full ASTM B622/B564/B366 range: seamless pipes, forged flanges, butt-weld fittings, plates. 3.1 certified, full-batch traceable, no PWHT required. Contact Us for inventory and expert support.
