Nimonic 81 is a nickel-based alloy that is part of Nimonic Alloy, a modification of Nimonic 80A. It contains a higher titanium-to-aluminum ratio, has higher resistance to creep deformation and stress embrittlement, and resists oxidation at elevated temperatures. It makes your stainless steel pipes and stainless steel pipe fittings more indestructible.
Nimonic 81 | UNS N07081
Nimonic 81 is a high quality high temperature material. Its composition includes titanium and aluminum, which allow it to be age-hardened. Age-hardening greatly increases its mechanical properties and also improves creep resistance. It works reliably at temperatures up to 815°C (1500°F).
Key Advantages of Nimonic 81
Deformation of Nimonic 81 is not easy, allowing it to retain its shape under prolonged high-temperature conditions and stresses.
Nimonic 81 alloy maintains mechanical strength and stability at temperatures up to 815°C (1500°F) and resists heat softening.
High chromium content provides surface protection and resistance to oxidation in extreme temperature conditions. Reduces the need for frequent replacement.
Nimonic 81 VS 310S Stainless Steel
| Feature | Nimonic 81 | 310S Stainless Steel |
|---|---|---|
| Cost | High | Medium |
| Fabrication | Requires specific heat treatment | Easier, more common |
| Creep Resistance | Excellent | Good |
| Primary Use | High-stress, high-temp components | High-temp, non-load-bearing |
Chemical Composition
| Element | Ni | Cr | Ti | Al | Fe | C | Si | Mn |
|---|---|---|---|---|---|---|---|---|
| Content (wt%) | Balance | 18.0-21.0 | 2.50-3.50 | 1.00-1.80 | 3.0 Max | 0.10 Max | 1.0 Max | 1.0 Max |
Mechanical Properties
| Property | Tensile Strength | Yield Strength (0.2% Offset) | Elongation | Hardness (HRC) | Max. Service Temp |
|---|---|---|---|---|---|
| Value (Typical) | ≥980MPa(142ksi) | ≥620MPa(90si) | ≥15 | ≥25 | Up To 815℃(1500℉) |
Nimonic 81 in High Temperature Piping Systems
- High Temperature Bolts and Fasteners: Preferred for joining high temperature flanges.
- Turbine Blades: Widely used in gas turbines, aerospace and power generation.
- Heat Exchanger Tubes: Can be used for heat exchanger tubes. They must resist thermal cycling.
- Piping Systems: Can be used for critical stainless steel fittings such as high pressure exhaust systems.
Sourcing and Fabricating Nimonic 81
A complete Material Test Report (MTR) is required. It verifies the precise composition of the alloy and ensures its performance.
Work with specialized suppliers of stainless steel pipe and fittings. They understand these alloy steels and can ensure proper fabrication and quality control,and are ISO 9001 and CE-PED certified.
It is difficult to machine and requires special tools. Specific welding techniques are essential to ensure the integrity of the weld.
It is expensive, so it is important to assess whether the product has a longer service life. This can justify its higher initial cost.
You May Also Want To Read:
Nimonic 75 Introduction | Nickel-based Alloy | Pipes | Fittings
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