# Inconel 718 vs A-286 Bolts: Which Superalloy Fastener for Your Application?

> Engineering comparison of Inconel 718 and A-286 bolts: temperature limits, tensile strength, cost, corrosion, and application-specific recommendations.

## Alloy Identification and Standards

| Alloy | UNS No. | DIN / EN | Common ASTM/AMS fastener standards |
|---|---|---|---|
| Inconel 718 | N07718 | 2.4668 / NiCr19NbMo | ASTM B637, AMS 5662 / 5663 / 5664 |
| A-286 | S66286 | 1.4980 / X5NiCrTiMoVB25-15-2 | ASTM A453 Grade 660, AMS 5731 / 5732 / 5737 |

## Chemical Composition, wt% (balance Fe)

| Element | Inconel 718 UNS N07718 | A-286 UNS S66286 |
|---|---|---|
| Ni | 50.0–55.0 | 24.0–27.0 |
| Cr | 17.0–21.0 | 13.5–16.0 |
| Nb + Ta | 4.75–5.50 | — |
| Mo | 2.80–3.30 | 1.00–1.50 |
| Ti | 0.65–1.15 | 1.90–2.35 |
| Al | 0.20–0.80 | ≤0.35 |
| V | — | 0.10–0.50 |
| Co | ≤1.0 | — |
| C | ≤0.08 | ≤0.08 |
| Mn | ≤0.35 | ≤2.00 |
| Si | ≤0.35 | ≤1.00 |
| P | ≤0.015 | ≤0.025 |
| S | ≤0.015 | ≤0.025 |
| B | ≤0.006 | 0.001–0.010 |

## Minimum Room-Temperature Mechanical Properties

| Property | Inconel 718 | A-286 |
|---|---|---|
| Condition | Solution annealed + aged | Solution treated + aged |
| Tensile strength, ksi / MPa | 185 / 1275 | 130 / 895 |
| Yield strength, 0.2% offset, ksi / MPa | 150 / 1034 | 85 / 586 |
| Elongation, % | 12 | 15 |
| Hardness, HB | 331–444 | 248–341 |
| Typical continuous service limit | 1300°F / 704°C | 1200°F / 649°C |

## Application Notes

**Inconel 718 (UNS N07718)**  
Use for high-strength bolting in gas turbines, oil and gas, nuclear, and cryogenic service. Offers high creep-rupture strength and oxidation resistance to 1300°F (704°C) under load. NACE MR0175 / ISO 15156 sour-service qualified in aged condition. Select when tensile/yield above 160 ksi / 120 ksi is required, or when chloride SCC and sour corrosion resistance are critical.

**A-286 (UNS S66286)**  
Precipitation-hardened austenitic stainless alloy for moderate-temperature fasteners, turbine frames, afterburners, and automotive turbocharger bolting. Good oxidation resistance to 1500°F (816°C) intermittent. Lower raw-material cost than Inconel 718 due to lower nickel content. Select when 85–100 ksi yield strength is sufficient, service temperature is below 1200°F (649°C), or cost is a primary driver.