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 Inconel 718 — Selection Guide for High-Temperature Bolting
A286 vs Inconel 718 is the most-asked engineering comparison in superalloy selection — both are precipitation-hardening superalloys used for jet-engine, gas-turbine, and high-temperature aerospace applications, but they differ in base composition (A286 = iron-base; Inconel 718 = nickel-base), mechanical properties, cost, and service-temperature ceiling. This page provides a side-by-side technical comparison covering chemistry, mechanical properties at room and elevated temperature, weldability, cost, and selection criteria. Quick answer: A286 wins for service ≤ 700 °C with cost-efficient non-magnetic bolting; Inconel 718 wins for service ≤ 700 °C requiring tensile strength > 1240 MPa or extended fatigue life. See parent A286 stainless steel, related A286 vs 17-4 PH, A286 vs Waspaloy, A286 vs Nimonic 80A, and the canonical A286 chemical composition + mechanical properties.
About A286 (UNS S66286)
A286 (UNS S66286) is an iron-nickel-chromium precipitation-hardening austenitic stainless steel — nominal composition 53 Fe-25 Ni-15 Cr-2 Ti-1.3 Mo with small additions of vanadium, aluminium and boron. Heat-treated to 130 ksi (895 MPa) tensile / 95 ksi (655 MPa) yield, retains useful mechanical properties from -196 °C to ~700 °C. Non-magnetic (permeability < 1.005). Covered by ASTM A453 grade 660, ASTM A638 grade 660, ASTM B637, AMS 5525-5895. Standard for jet-engine compressor and turbine bolting, gas-turbine combustor hardware, automotive turbocharger waste-gates, and oil & gas downhole tools. Cost-effective vs nickel-base alternatives.
About Inconel 718 (UNS N07718)
Inconel 718 (UNS N07718) is a nickel-iron-chromium precipitation-hardening superalloy — nominal composition 52 Ni-19 Fe-19 Cr-3 Mo-5 Nb-1 Ti-0.5 Al with small carbon and boron additions. Heat-treated to 180 ksi (1240 MPa) tensile / 150 ksi (1035 MPa) yield, retains mechanical properties to ~700 °C with superior fatigue and stress-rupture strength vs A286. Non-magnetic. Covered by AMS 5662 / 5663 / 5664 / 5665, ASTM B637. The dominant material for jet-engine high-pressure turbine discs, blades, and turbo-pump impellers. Higher tensile and creep strength than A286 but 3-4× the cost.
A286 vs Inconel 718 — Selection Guide for High-Temperature Bolting — Side-by-Side Comparison
| Property | A286 (UNS S66286) | Inconel 718 (UNS N07718) | Notes |
|---|---|---|---|
| Base composition | Fe-Ni-Cr (Fe-base) | Ni-Fe-Cr (Ni-base) | Different base classifications |
| Density (g/cm³) | 7.94 | 8.19 | Inconel 718 ~3 % heavier |
| Yield strength (MPa) RT | ≥ 655 | ≥ 1035 | Inconel 718 ~58 % higher yield |
| Tensile strength (MPa) RT | ≥ 895 | ≥ 1240 | Inconel 718 ~39 % higher tensile |
| Yield at 540 °C (MPa) | ~620 | ~970 | Both retain strength well |
| Yield at 700 °C (MPa) | ~485 | ~825 | Inconel 718 retains more strength |
| Stress rupture 1000 h at 650 °C (MPa) | ~415 | ~620 | Inconel 718 ~50 % better stress rupture |
| Service temperature max (°C) | ~700 (continuous) | ~700 (continuous) | Both limited above 700 °C |
| Oxidation resistance max (°C) | 982 | 982 | Similar oxidation ceiling |
| Modulus of elasticity (GPa) | 199 | 200 | Essentially identical |
| Thermal expansion (µm/m·°C 20-300 °C) | 17.0 | 13.0 | Inconel 718 lower expansion — better thermal-cycling fatigue |
| Magnetic permeability | < 1.005 | < 1.005 | Both non-magnetic |
| Cost relative | 1.0× | 3-4× | Inconel 718 significantly more expensive |
| Weldability | Good (sol-treated) | Excellent (vs strain-age cracking) | Inconel 718 has dedicated low-strain-age-cracking property |
| NACE MR0175 sour-service | Yes (≤ HRC 35) | Yes (≤ HRC 40) | Both compliant when hardness verified |
| Cryogenic toughness retention | 85 % at -196 °C | 90 % at -196 °C | Both excellent for cryogenic service |
| Best for | Cost-efficient ≤ 700 °C bolting | High-strength ≤ 700 °C critical components | Choose by cost vs strength priority |
When to Choose Each Alloy
- Choose A286 when: Service temperature ≤ 700 °C AND cost is a primary driver. A286 is one-third the cost of Inconel 718 and meets the same temperature ceiling. Ideal for high-volume aerospace fastener (compressor disc bolting, casing-split bolts), gas-turbine combustor hardware, and automotive turbocharger waste-gate bolting.
- Choose Inconel 718 when: Service temperature ≤ 700 °C AND application requires room-temperature tensile > 1240 MPa, OR requires superior stress-rupture and fatigue strength (jet-engine high-pressure turbine discs, gas-turbine compressor stage 1-2 blades). Pay 3-4× cost premium for the strength.
- Both alloys are equivalent when: Service temperature ≤ 540 °C AND no specific high-strength or fatigue requirement. A286 is preferred by default — same corrosion + temperature performance at one-third the cost.
- Cryogenic service comparison: Both retain 85-90 % of room-temperature toughness at -196 °C — equivalent for LNG and hydrogen-storage applications. A286 cost-effective; Inconel 718 only when cryogenic strength + LNG temperature combine.
- Above 700 °C service: Neither — choose Waspaloy for sustained 650-870 °C service.
Applications by Industry
- Jet-engine compressor disc bolting: A286 NAS 6603 12-point standard for compressor disc-to-disc retention. Inconel 718 used for higher-strength applications in stage 1-2 high-pressure turbine bolting.
- Gas-turbine combustor liner: A286 for combustor liner attachment bolting (lower preload requirement). Inconel 718 for liner shells themselves (high-strength aerospace machining).
- Aerospace turbo-pump impellers: Inconel 718 dominant for liquid-rocket turbo-pump impellers — fatigue strength + cryogenic LNG/LH2 compatibility critical.
- Automotive turbocharger components: A286 for waste-gate bolting, exhaust manifold flange bolts (cost-driven). Inconel 718 only for high-end racing turbo wheels and shafts.
- Oil & gas downhole bolting: A286 for sour-service downhole tool bolting (NACE MR0175 ≤ HRC 35). Inconel 718 also acceptable but at 3-4× cost.
- Cryogenic LNG / hydrogen: A286 for LNG valve-bonnet bolting + hydrogen storage internals. Inconel 718 for safety-critical cryogenic engine pumps.
A286 vs Inconel 718 — Selection Guide for High-Temperature Bolting — Frequently Asked Questions
What's the main difference between A286 and Inconel 718?
A286 is iron-base (53 % Fe), Inconel 718 is nickel-base (52 % Ni). A286 is one-third the cost; Inconel 718 has 39 % higher tensile strength and 50 % better stress rupture. Both retain mechanical properties to ~700 °C and are non-magnetic.
Can A286 replace Inconel 718?
For service ≤ 700 °C and applications not requiring tensile > 1240 MPa — yes. A286 is one-third the cost. NOT for stage 1-2 high-pressure turbine discs or applications requiring superior stress rupture / fatigue performance.
Which is more weldable, A286 or Inconel 718?
Inconel 718 has dedicated alloying (5 % Nb instead of Ti) specifically to resist strain-age cracking during welding — superior weldability vs A286. A286 is good but requires post-weld solution-treatment + aging for full-strength weld zone.
Which has higher temperature ceiling, A286 or Inconel 718?
Both ~700 °C continuous service. Inconel 718 retains more strength at high temperature (yield 825 MPa vs A286 485 MPa at 700 °C). For sustained service > 700 °C, choose Waspaloy instead of either.
Cost ratio A286 vs Inconel 718?
A286 is approximately 1/3 the cost of Inconel 718 — A286 raw material cost ~$8-15/kg vs Inconel 718 ~$25-50/kg depending on form and quantity. For high-volume fastener applications, A286 cost advantage compounds significantly.
Is A286 stronger than Inconel 718 in any condition?
No. Inconel 718 has higher tensile, yield, and stress-rupture strength at all temperatures. A286 advantages are: lower cost (~1/3), lower density (3 % lighter), and easier machining. For high-strength applications Inconel 718 wins; for cost-optimized A286 wins.
Are both alloys NACE MR0175 sour-service compliant?
Yes — both with hardness verification: A286 ≤ HRC 35, Inconel 718 ≤ HRC 40. Specify on PO; each heat receives Vickers traverse before release for sour-service oilfield applications.
Do they have the same thermal expansion?
No — A286 thermal expansion 17.0 µm/m·°C is higher than Inconel 718 at 13.0 µm/m·°C. Inconel 718 lower expansion provides better thermal-cycling fatigue resistance — important for cycling jet-engine hot-section components.
Which alloy for jet-engine compressor disc bolting?
A286 NAS 6603 12-point bolts are the dominant choice — cost-efficient and meets the 540-700 °C service requirement. Inconel 718 used only when higher-strength variant is specified by OEM. See A286 jet engine fasteners.
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.
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