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Material Specification

Alloy 80A

Alloy 80A Fasteners
Age-Hardenable Nickel-Chromium Alloy – Turbine Bolting & Exhaust Valve Service to 815°C

Nimonic 80A Fasteners

Buy Nimonic Alloy 80A (UNS N07080 / Werkstoff 2.4952 & 2.4631 / BS HR 1, 201, 401 & 601) bolts, stud bolts, heavy hex nuts, socket cap screws, and custom CNC fasteners from Exotic Alloy. Nimonic 80A is a wrought, age-hardenable nickel-chromium alloy strengthened by additions of titanium, aluminium and carbon, developed for service at temperatures up to 815°C (1500°F).

Exotic Alloy manufactures Nimonic 80A fasteners to BS HR 1, 201, 401 and 601 and customer specification in metric M6–M100 and imperial ¼"–4" sizes, supplied solution treated and aged with full EN 10204 3.1 material test certificates. Alloy 80A is one of the most widely specified high-temperature bolting materials in the world, and is also used for gas turbine blades, rings and discs, nuclear boiler tube supports and automobile exhaust valves.

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Product Range

Alloy 80A Fasteners Available

Alloy 80A Hex Bolts
Alloy 80A
Hex Bolts
Alloy 80A Heavy Hex Bolts
Alloy 80A
Heavy Hex Bolts
Alloy 80A Stud Bolts
Alloy 80A
Stud Bolts
Alloy 80A Threaded Rods
Alloy 80A
Threaded Rods
Alloy 80A Anchor Bolts
Alloy 80A
Anchor Bolts
Alloy 80A Hex Nuts
Alloy 80A
Hex Nuts
Alloy 80A Washers
Alloy 80A
Washers
Alloy 80A Cotter Pins
Alloy 80A
Cotter Pins
Alloy 80A Springs
Alloy 80A
Springs
Alloy 80A Circlips
Alloy 80A
Circlips
Alloy 80A Coated Fasteners
Alloy 80A
Coated Fasteners
Alloy 80A Custom Spacers
Alloy 80A
Custom Spacers
Technical Data

Alloy 80A Specifications

Chemical Composition — Nimonic 80A (wt. %)
ElementNiCrTiAlCoFeMnSiC
Min %Balance18.001.801.00–––––
Max %Balance21.002.701.802.003.001.001.000.10
Mechanical Properties — Nimonic 80A
ConditionUTS (MPa)YS 0.2% (MPa)Elongation (%)Hardness
Solution Treated (Typical Bar)83043045≤ 240 HB
Solution Treated & Aged (Typical Bar)120078025300–350 HB
Solution Treated & Aged (Typical Sheet)110070030280–330 HB
Cold Worked & Aged (High Strength Bolting)1240–1380900–103012–20350–390 HB
Physical Properties
Density8.19 g/cm³
Melting Range1320–1365°C (2410–2490°F)
Specific Heat Capacity448 J/kg·K at 20°C
Magnetic Permeability1.000601 for 200–2000 oersted
Maximum Service Temperature815°C (1500°F)
Young’s Modulus222 GPa at 20°C (typical)
Equivalent Grades & Standards
UNSWerkstoff / DINEN DesignationCommon Name
N07080 2.4952 / 2.4631 NiCr20TiAl Nimonic 80A

Key Specifications: BS HR 1, HR 201, HR 401 & HR 601 / BS 3076 NA20 / DIN 17742 / customer specification; all fasteners supplied with EN 10204 3.1 material test certification

Machinability: Nimonic 80A machines best in the solution-treated condition before ageing, where it behaves like a tough austenitic material. Use rigid setups, sharp positive-rake carbide tooling at 25–40 SFM, heavy positive feeds and generous depth of cut with continuous flood coolant. Rough machine and roll threads before the age cycle wherever possible; the aged alloy reaches 300–350 HB and requires light sharp finishing cuts.

Welding: As a gamma prime hardened alloy, Nimonic 80A is susceptible to strain-age cracking if welded in the aged condition. Weld on solution-treated material using matching or NIMONIC 80A filler, then apply a full solution treatment and re-age. Alloy 263 and PK33 were both developed specifically to offer improved ductility in welded assemblies as replacements for 80A in fabricated sheet structures.

Forging: Hot forge between 1050–1180°C (1920–2155°F), finishing above 950°C (1740°F). Material for extrusion is produced by high-frequency melting and casting in air; electroslag refined stock is used for forgings, and vacuum refined versions are available for critical applications.

Heat Treatment: The standard cycle for bar is 8 hours at 1080°C (1976°F) air cool, followed by 16 hours at 700°C (1292°F) air cool. This solution treats the matrix and then precipitates the gamma prime that develops the alloy’s strength. For bolting applications the ageing temperature is sometimes raised to improve relaxation resistance at service temperature; confirm the required cycle at order stage.

Nimonic 80A combines the oxidation resistance conferred by its 20% chromium content with the creep and relaxation resistance developed by gamma prime precipitation, making it the reference material for high-temperature bolting up to 815°C (1500°F). Its resistance to stress relaxation is the property that matters most in fastener service, since it determines how long a joint retains preload at temperature. The alloy also resists oxidation and scaling in cyclic service and performs well in combustion atmospheres. Where hot corrosion from alkali metal sulfates and chlorides is the governing mechanism, Nimonic 81 with its 30% chromium is the better choice.

Key Characteristics

  • The reference age-hardenable alloy for high-temperature bolting to 815°C.
  • Excellent resistance to stress relaxation — joints retain preload at temperature.
  • Gamma prime strengthened by titanium and aluminium additions.
  • Good oxidation and scaling resistance from 20% chromium.
  • Available electroslag and vacuum refined for critical applications.

Typical Applications

  • Gas turbines: high-temperature casing, flange and rotor bolting.
  • Turbine hardware: blade, ring and disc fastener assemblies.
  • Nuclear power: boiler tube support bolting.
  • Automotive: exhaust valve and turbocharger fastener applications.
  • Die casting: insert and core fixing hardware.