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Material Specification

Alloy C276

Alloy C276 Fasteners
Nickel-Molybdenum-Chromium-Tungsten Alloy – The Industry Benchmark CRA

Hastelloy C-276 Fasteners

Buy Hastelloy Alloy C-276 (UNS N10276 / Werkstoff 2.4819 / ASTM B574) bolts, stud bolts, heavy hex nuts, socket cap screws, and custom CNC fasteners from Exotic Alloy. Hastelloy C-276 is the most widely specified corrosion-resistant alloy in the world, containing approximately 16% Mo, 15.5% Cr and 3.75% W with very low carbon and silicon, making it resistant to a broader range of aggressive chemical environments than almost any other single material.

Exotic Alloy manufactures Hastelloy C-276 fasteners conforming to ASTM B574, ASTM F467, ASTM F468, ASME SB-574, AMS 5750 and NACE MR0175 / ISO 15156-3 in metric M6–M100 and imperial ¼"–4" sizes with full EN 10204 3.1 material test certificates for chemical processing, flue gas desulphurisation, sour gas and marine applications.

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Product Range

Alloy C276 Fasteners Available

Alloy C276 Hex Bolts
Alloy C276
Hex Bolts
Alloy C276 Heavy Hex Bolts
Alloy C276
Heavy Hex Bolts
Alloy C276 Stud Bolts
Alloy C276
Stud Bolts
Alloy C276 Threaded Rods
Alloy C276
Threaded Rods
Alloy C276 Anchor Bolts
Alloy C276
Anchor Bolts
Alloy C276 Hex Nuts
Alloy C276
Hex Nuts
Alloy C276 Washers
Alloy C276
Washers
Alloy C276 Cotter Pins
Alloy C276
Cotter Pins
Alloy C276 Springs
Alloy C276
Springs
Alloy C276 Circlips
Alloy C276
Circlips
Alloy C276 Coated Fasteners
Alloy C276
Coated Fasteners
Alloy C276 Custom Spacers
Alloy C276
Custom Spacers
Technical Data

Alloy C276 Specifications

Chemical Composition — Hastelloy C-276 (wt. %)
ElementNiMoCrFeWCoMnSiC
Min %Balance15.0014.504.003.00––––
Max %Balance17.0016.507.004.502.501.000.080.01
Mechanical Properties — Hastelloy C-276
ConditionUTS (MPa)YS 0.2% (MPa)Elongation (%)Hardness
Solution Annealed (ASTM B574 Minimum)≥ 690≥ 283≥ 40≤ 100 HRB
Solution Annealed (Typical Bar)7903556089 HRB
Cold Drawn / Stress Relieved900–1070620–83015–2525–32 HRC
Hot Finished Forged Bar760–860345–41545–55≤ 210 HB
Physical Properties
Density8.89 g/cm³
Melting Range1325–1370°C (2415–2500°F)
Specific Heat Capacity427 J/kg·K at 20°C
Thermal Conductivity10.2 W/m·K at 100°C
Thermal Expansion11.2 µm/m·°C (20–100°C)
Electrical Resistivity1.30 µΩ·m
Equivalent Grades & Standards
UNSWerkstoff / DINEN DesignationCommon Name
N10276 2.4819 NiMo16Cr15W Alloy C276

Key Specifications: ASTM B574 (Rod/Bar) / ASTM B575 (Plate & Sheet) / ASTM B619, B622, B626 (Tube) / ASTM B564 (Forgings) / ASTM B462 (Flanges) / ASTM F467 & F468 (Nuts & Bolts) / AMS 5750 / NACE MR0175

Machinability: Hastelloy C-276 work-hardens rapidly and its tungsten and molybdenum content is highly abrasive. Machine with rigid, backlash-free setups, sharp positive-rake carbide tooling at 20–35 SFM, heavy positive feeds and a generous depth of cut so the tool always engages virgin metal beneath the work-hardened skin. Continuous flood coolant is mandatory; any dwell or rubbing hardens the surface and destroys tool life.

Welding: C-276 is readily welded by GTAW, GMAW, SMAW and plasma arc processes using matching ERNiCrMo-4 filler wire or ENiCrMo-4 electrodes. Pre-heat is not required and post-weld heat treatment is not normally necessary because the very low carbon and silicon content suppresses grain-boundary precipitation. Keep interpass temperature below 150°C and heat input low to minimise mu-phase formation.

Forging: Hot forge between 1065–1230°C (1950–2250°F) and finish above 980°C (1800°F), reheating as necessary. Working below the finishing temperature promotes edge cracking and intermetallic precipitation. Cold heading and cold forging are practicable for smaller fastener diameters with intermediate solution anneals.

Heat Treatment: Solution anneal at 1121–1149°C (2050–2100°F) followed by rapid water quench. Rapid cooling through 550–1040°C is essential to avoid carbide and mu-phase precipitation at grain boundaries, which would reduce both ductility and corrosion resistance. C-276 is not age-hardenable; strength above annealed is developed only by cold work, limited to 40 HRC maximum for NACE MR0175 sour service.

Hastelloy C-276 resists an exceptionally broad spectrum of media: strongly oxidising ferric and cupric chlorides, hot contaminated mineral acids, chlorine, formic and acetic acids, acetic anhydride, seawater and brine, and hypochlorite and chlorine dioxide solutions. It is one of very few materials that withstands wet chlorine gas and hypochlorite. High molybdenum and tungsten confer outstanding localised corrosion resistance, with a pitting resistance equivalent number of approximately 68, and the high nickel base gives excellent immunity to chloride-induced stress-corrosion cracking. Its very low carbon and silicon content means welded assemblies resist intergranular attack in the as-welded condition.

Key Characteristics

  • The most versatile corrosion-resistant alloy available — oxidising and reducing media.
  • Resists wet chlorine gas, hypochlorite and chlorine dioxide solutions.
  • Outstanding resistance to pitting, crevice corrosion and chloride SCC.
  • Very low carbon and silicon — welds resist intergranular attack as-welded.
  • NACE MR0175 / ISO 15156-3 qualified for sour hydrocarbon service.

Typical Applications

  • Chemical processing: reactor, evaporator and heat exchanger bolting.
  • Flue gas desulphurisation: scrubber, absorber and stack liner fasteners.
  • Sour gas and offshore: wellhead, manifold and flange bolting to NACE MR0175.
  • Pulp and paper: chlorine dioxide bleach plant and digester hardware.
  • Pharmaceutical and waste treatment: reactor closure and incinerator fasteners.