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Material Specification

Alloy C22

Alloy C22 Fasteners
Nickel-Chromium-Molybdenum-Tungsten Alloy – Oxidising & Reducing Service

Hastelloy C-22 Fasteners

Buy Hastelloy Alloy C-22 (UNS N06022 / Werkstoff 2.4602 / ASTM B574) bolts, stud bolts, heavy hex nuts, socket cap screws, and custom CNC fasteners from Exotic Alloy. Hastelloy C-22 is a nickel-chromium-molybdenum-tungsten alloy containing approximately 22% Cr, 13% Mo and 3% W, giving it better overall versatility than C-276 in mixed acid service and outstanding resistance to localised corrosion, with a pitting resistance equivalent number above 65.

Exotic Alloy manufactures Hastelloy C-22 fasteners conforming to ASTM B574, ASTM F467, ASTM F468, ASME SB-574 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 flue gas desulphurisation, chemical processing, pharmaceutical and sour gas applications.

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Product Range

Alloy C22 Fasteners Available

Alloy C22 Hex Bolts
Alloy C22
Hex Bolts
Alloy C22 Heavy Hex Bolts
Alloy C22
Heavy Hex Bolts
Alloy C22 Stud Bolts
Alloy C22
Stud Bolts
Alloy C22 Threaded Rods
Alloy C22
Threaded Rods
Alloy C22 Anchor Bolts
Alloy C22
Anchor Bolts
Alloy C22 Hex Nuts
Alloy C22
Hex Nuts
Alloy C22 Washers
Alloy C22
Washers
Alloy C22 Cotter Pins
Alloy C22
Cotter Pins
Alloy C22 Springs
Alloy C22
Springs
Alloy C22 Circlips
Alloy C22
Circlips
Alloy C22 Coated Fasteners
Alloy C22
Coated Fasteners
Alloy C22 Custom Spacers
Alloy C22
Custom Spacers
Technical Data

Alloy C22 Specifications

Chemical Composition — Hastelloy C-22 (wt. %)
ElementNiCrMoWFeCoMnSiC
Min %Balance20.0012.502.502.00––––
Max %Balance22.5014.503.506.002.500.500.080.015
Mechanical Properties — Hastelloy C-22
ConditionUTS (MPa)YS 0.2% (MPa)Elongation (%)Hardness
Solution Annealed (ASTM B574 Minimum)≥ 690≥ 310≥ 45≤ 100 HRB
Solution Annealed (Typical Bar)8004056290 HRB
Cold Drawn / Stress Relieved900–1070620–83015–2525–32 HRC
Hot Finished Forged Bar760–860350–42050–60≤ 225 HB
Physical Properties
Density8.69 g/cm³
Melting Range1357–1399°C (2475–2550°F)
Specific Heat Capacity414 J/kg·K at 20°C
Thermal Conductivity10.1 W/m·K at 100°C
Thermal Expansion12.4 µm/m·°C (20–100°C)
Electrical Resistivity1.14 µΩ·m
Equivalent Grades & Standards
UNSWerkstoff / DINEN DesignationCommon Name
N06022 2.4602 NiCr21Mo14W Alloy 22 / C-22

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) / NACE MR0175

Machinability: Hastelloy C-22 work-hardens rapidly and its tungsten content makes it abrasive on tooling. Use rigid setups, sharp positive-rake carbide at 20–35 SFM, heavy uninterrupted feeds and continuous flood coolant. Allow generous depth of cut so the edge works below the hardened layer produced by the previous pass. Thread rolling is preferred to cutting wherever section size permits.

Welding: C-22 is readily welded by GTAW, GMAW, SMAW and plasma arc using matching ERNiCrMo-10 filler wire or ENiCrMo-10 electrodes. No pre-heat is required and post-weld heat treatment is not normally necessary. Keep heat input low and interpass temperature below 150°C. The alloy is markedly resistant to weld-zone precipitation and to hot cracking.

Forging: Hot forge between 1080–1230°C (1975–2250°F), finishing above 980°C (1800°F). Reheat as required rather than continuing below the finishing temperature. Cold forging and cold heading are practicable in smaller diameters with intermediate anneals.

Heat Treatment: Solution anneal at 1121–1149°C (2050–2100°F) followed by rapid water quench to redissolve carbides and intermetallic phases. Slow cooling permits grain-boundary precipitation that reduces corrosion resistance. Hastelloy C-22 is not age-hardenable; higher strength is achieved only by cold work, which for NACE MR0175 sour service must leave hardness at or below 40 HRC.

Hastelloy C-22 offers better overall resistance to oxidising media than C-276 thanks to its higher chromium, while retaining the molybdenum and tungsten needed for reducing acids. It resists wet chlorine, hypochlorite and chlorine dioxide solutions, ferric and cupric chlorides, hot contaminated mineral acids, nitric acid, formic and acetic acids, and seawater. Its pitting resistance equivalent number of roughly 66–70 gives outstanding immunity to chloride pitting and crevice corrosion, and the high nickel base provides excellent resistance to chloride stress-corrosion cracking. C-22 also resists weld-zone attack in the as-welded condition.

Key Characteristics

  • Outstanding resistance in both oxidising and reducing environments.
  • Pitting resistance equivalent number above 65 — exceptional chloride pitting immunity.
  • Superior resistance to crevice corrosion and chloride stress-corrosion cracking.
  • Resists wet chlorine, hypochlorite and chlorine dioxide bleaching solutions.
  • Excellent weldability with no post-weld heat treatment normally required.

Typical Applications

  • Flue gas desulphurisation: absorber, duct and stack liner bolting.
  • Chemical processing: mixed acid, chlorination and oxidiser service fasteners.
  • Pharmaceutical industry: reactor, autoclave and filter closure bolting.
  • Pulp and paper: chlorine dioxide bleach plant fastener assemblies.
  • Sour gas and offshore: NACE MR0175 qualified wellhead and flange bolting.