Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
A286 vs Nimonic 80A — High-Temperature Alloy Selection
A286 vs Nimonic 80A compares an iron-base precipitation-hardening superalloy to a nickel-base solid-solution + gamma-prime-strengthened superalloy. Nimonic 80A is the most-used Nimonic-series alloy and is the dominant material for diesel-engine exhaust valves, gas-turbine 1st-stage turbine blades, and high-temperature spring applications above A286's 700 °C ceiling. Service-temperature ceiling is the primary differentiator: A286 is suitable to ~700 °C; Nimonic 80A retains useful properties to ~815 °C continuous. Cost difference: Nimonic 80A is ~3-4× the cost of A286. Quick answer: A286 wins for service ≤ 700 °C with cost efficiency and non-magnetic; Nimonic 80A is required for sustained 700-815 °C service in exhaust valves and gas-turbine hot sections. See parent A286 stainless steel, related A286 vs Inconel 718, A286 vs Waspaloy, A286 vs 17-4 PH.
About A286 (UNS S66286)
A286 (UNS S66286) is an iron-nickel-chromium precipitation-hardening austenitic stainless steel — composition 53 Fe-25 Ni-15 Cr-2 Ti-1.3 Mo. Heat-treated to 895 MPa tensile, 655 MPa yield. Service temperature -196 °C to ~700 °C. Non-magnetic. Cost-effective for jet-engine bolting up to 700 °C. Covered by ASTM A453 grade 660, AMS 5525-5895.
About Nimonic 80A (UNS N07080)
Nimonic 80A (UNS N07080) is a nickel-chromium gamma-prime-strengthened nickel-base superalloy — composition 76 Ni-19 Cr-2.4 Ti-1.4 Al-0.06 C-0.001 B. Heat-treated to 1240 MPa tensile, 800 MPa yield. Service temperature -100 °C to ~815 °C continuous. Non-magnetic. Covered by AMS 5589 / 5398, BS HR1. The dominant material for diesel-engine exhaust valves (large bore — locomotive, marine, stationary diesel), gas-turbine 1st-stage turbine blades, and high-temperature springs in hot-section applications. ~3-4× the cost of A286.
A286 vs Nimonic 80A — High-Temperature Alloy Selection — Side-by-Side Comparison
| Property | A286 (UNS S66286) | Nimonic 80A (UNS N07080) | Notes |
|---|---|---|---|
| Base composition | Fe-Ni-Cr (Fe-base) | Ni-Cr-Ti-Al (Ni-base) | Different bases |
| Density (g/cm³) | 7.94 | 8.19 | Nimonic 80A ~3 % heavier |
| Yield strength (MPa) RT | ≥ 655 | ≥ 800 | Nimonic ~22 % higher yield |
| Tensile strength (MPa) RT | ≥ 895 | ≥ 1240 | Nimonic ~38 % higher tensile |
| Yield at 700 °C (MPa) | ~485 | ~620 | Nimonic better elevated-temp |
| Yield at 815 °C (MPa) | ~205 (degraded) | ~485 | Only Nimonic retains useful strength |
| Stress rupture 1000 h at 815 °C (MPa) | ~140 | ~280 | Nimonic 2× better high-temp stress rupture |
| Service temperature max (°C) | ~700 (continuous) | ~815 (continuous) | Nimonic 115 °C higher ceiling |
| Oxidation resistance max (°C) | 982 | 1095 | Nimonic superior |
| Magnetic | No (< 1.005) | No | Both non-magnetic |
| Modulus of elasticity (GPa) | 199 | 222 | Nimonic stiffer |
| Thermal expansion (µm/m·°C 20-300 °C) | 17.0 | 12.7 | Nimonic lower expansion |
| Cost relative | 1.0× | 3-4× | Significant premium |
| Weldability | Good (sol-treated) | Limited (gamma-prime cracking) | Nimonic welding challenging |
| Best for | ≤ 700 °C cost-efficient | 700-815 °C exhaust valves / blades | Choose by service temperature |
When to Choose Each Alloy
- Choose A286 when: Service temperature ≤ 700 °C AND cost efficiency matters. A286 is one-third the cost of Nimonic 80A. Ideal for jet-engine compressor and turbine bolting, gas-turbine combustor hardware, and aerospace structural fasteners up to 700 °C.
- Choose Nimonic 80A when: Service temperature 700-815 °C continuous — A286 cannot maintain strength at this range. Required for diesel-engine exhaust valves (locomotive, marine, stationary diesel), gas-turbine 1st-stage turbine blades, hot-section spring applications.
- Both alloys are equivalent when: Service temperature 540-650 °C with ample design margin. A286 preferred by default — same corrosion + non-magnetic performance at one-third the cost. Use Nimonic 80A only when temperature drives.
- Above 815 °C service: Neither — choose Waspaloy, René 41, or single-crystal nickel superalloys for extreme high-temperature applications.
- Spring applications at temperature: Nimonic 80A is preferred for hot-section springs above 540 °C — retains spring-back to 815 °C. A286 acceptable only for spring service ≤ 700 °C.
Applications by Industry
- Jet-engine compressor / turbine bolting: A286 dominant for compressor and casing-split bolting (≤ 700 °C). Nimonic 80A only for hot-section critical bolts at 700-815 °C.
- Diesel-engine exhaust valves (large-bore): Nimonic 80A dominant for locomotive, marine, and stationary diesel exhaust valves — operating temp 700-820 °C exceeds A286 ceiling. Critical specification for ASME, IACS, MAN B&W, Wärtsilä, MTU diesel engine valves.
- Gas-turbine 1st-stage turbine blades: Nimonic 80A historical choice for industrial gas-turbine 1st-stage blades. Modern engines use single-crystal nickel superalloys but Nimonic 80A still used in repair and re-blading.
- Aerospace cold-section structural: A286 dominates aerospace structural fasteners and brackets ≤ 700 °C. Nimonic 80A only when heat exposure is concentrated.
- Hot-section springs (gas-turbine): Nimonic 80A for hot-section springs above 540 °C operation — retains spring-back to 815 °C. A286 springs only for service ≤ 700 °C.
- Power-generation steam-turbine hot section: Nimonic 80A for steam-turbine high-pressure stages. A286 for cold-section auxiliary applications.
A286 vs Nimonic 80A — High-Temperature Alloy Selection — Frequently Asked Questions
What's the main difference between A286 and Nimonic 80A?
Service temperature: A286 ~700 °C, Nimonic 80A ~815 °C. Cost: Nimonic 80A is 3-4× more expensive. Base: A286 is iron-base; Nimonic 80A is nickel-base. For ≤ 700 °C, A286 is cost-efficient; for 700-815 °C, Nimonic 80A is required.
Why is Nimonic 80A used for diesel exhaust valves?
Diesel-engine exhaust valves operate at 700-820 °C — exceeds A286 ceiling. Nimonic 80A retains creep strength + oxidation resistance at this temperature, with proven 30+ year service history in marine and locomotive diesel exhaust valves. A286 inadequate for this application.
Cost comparison: A286 vs Nimonic 80A?
A286 is 1/3 to 1/4 the cost of Nimonic 80A — A286 raw material ~$8-15/kg vs Nimonic 80A ~$30-50/kg depending on form. Higher chromium and titanium content drive Nimonic cost.
Is Nimonic 80A weldable?
Limited — Nimonic 80A is susceptible to strain-age cracking during welding due to gamma-prime precipitation kinetics. Welding requires special procedures and post-weld heat treatment. A286 welding is more straightforward.
Are both alloys non-magnetic?
Yes — both A286 and Nimonic 80A are non-magnetic (permeability < 1.005). Compatible with instrumentation, MRI, and aerospace electromagnetic-sensitive applications.
Can A286 replace Nimonic 80A?
NOT for service > 700 °C. A286 loses strength rapidly while Nimonic 80A retains 60 % of room-temperature yield at 815 °C. For diesel exhaust valves and gas-turbine 1st-stage components, Nimonic 80A is required.
Which alloy for hot-section springs?
Nimonic 80A for service > 540 °C — retains spring-back at 700-815 °C. A286 acceptable for spring service ≤ 700 °C with ample design margin. Choose by service temperature.
Is Nimonic 80A export-restricted?
Generally no — Nimonic 80A has zero cobalt (vs Waspaloy's 13.5 %). It is not subject to the same export restrictions as Waspaloy. For export-friendly high-temperature alloy: Nimonic 80A or A286 depending on temperature.
Which alloy for diesel exhaust valve seat?
Nimonic 80A — operating temp + corrosion + valve-seat dynamics demand its specific properties. A286 inadequate. A286 gas turbine applications for non-valve hardware.
Related Comparisons & A286 Reference
Compare A286 against other precipitation-hardening alloys: A286 vs Inconel 718 · A286 vs 17-4 PH · A286 vs Waspaloy · A286 vs Nimonic 80A · A286 equivalent grades cross-reference.
Canonical A286 reference: A286 chemical composition · A286 mechanical properties · A286 heat treatment · A286 machinability · AMS / ASTM specifications hub.
Satisfaction Survey
