RAYCHIN LIMITED

Nimonic Nuts – Comprehensive Product Range

Critical Applications of Nimonic Nuts

International Standards & Global Designations – Nimonic Nuts

RAYCHIN LIMITED manufactures Nimonic nuts from vacuum induction melted (VIM) and vacuum arc remelted (VAR) or electroslag remelted (ESR) material conforming to the most widely used national and international specifications. All material is traceable to the mill.

Chemical Composition (Weight %) – Nimonic Alloys

Our Nimonic nuts are produced from vacuum induction melted (VIM) and vacuum arc remelted (VAR) material conforming to the limits of applicable AMS, BS, and ASTM standards.

Nimonic 90 (UNS N07090 / W.Nr 2.4632)

Nimonic 80A (UNS N07080 / W.Nr 2.4952)

Nimonic 75 (UNS N06075 / W.Nr 2.4630)

Metallurgical note: Nimonic alloys are precipitation-hardening nickel-based superalloys strengthened through the formation of gamma prime (γ') phase Ni₃(Al, Ti) in a disordered FCC matrix. Nimonic 90 contains cobalt additions (15-21%) for enhanced solid solution strengthening and creep resistance at elevated temperatures up to 920°C. Nimonic 80A is strengthened with aluminum and titanium additions and offers good creep and oxidation resistance up to 815°C, with wide application in gas turbine nuts and fasteners. Nimonic 75 is a solid-solution strengthened alloy with good oxidation resistance up to 1050°C and excellent fabricability, used for applications requiring medium strength at high operating temperatures. The alloys are produced by vacuum induction melting (VIM) and vacuum arc remelting (VAR) or electroslag remelting (ESR) to ensure high purity and consistent properties. These alloys work-harden during machining and require specialized techniques and tooling.

Complete Mechanical & Physical Properties – Nimonic Alloys (MPa / ksi)

Nimonic nuts are supplied in fully heat-treated condition per applicable AMS, BS, and ASTM specifications. Data represent typical values based on industry standards. For aerospace nuts, proof load testing is performed to ensure compliance with specified strength requirements.

Nimonic 90 – Mechanical Properties

Nimonic 80A – Mechanical Properties

Nimonic 75 – Mechanical Properties

High-Temperature Mechanical Properties – Nimonic 75

Physical Properties – Nimonic Alloys

High‑Temperature Performance of Nimonic Nuts

Nimonic alloys are renowned for exceptional high-temperature strength and stability, maintaining useful mechanical properties up to 950°C (1740°F) in oxidizing atmospheres. Nimonic 90 exhibits high stress-rupture strength and excellent creep resistance up to 920°C, making it ideal for critical nut applications in gas turbines and aerospace assemblies where sustained mechanical integrity is required at elevated temperatures. The alloy maintains significant strength at elevated temperatures with good oxidation resistance, allowing nuts to maintain clamping force under extreme thermal cycling. Nimonic 80A offers good creep and oxidation resistance up to 815°C and is widely used in gas turbine nuts, nuclear applications, and automotive exhaust components. For aerospace nuts, Nimonic 80A is typically used where operating temperatures reach 800°C. Nimonic 75 provides good oxidation resistance up to 1050°C for less demanding applications requiring medium strength, such as industrial furnace components and heat treatment fixtures. The γ' phase strengthening mechanism ensures stable microstructure during long-term high-temperature service. Dynamic recrystallization occurs at specific temperature ranges (1130°C for Nimonic 90, 1150°C for Nimonic 80A, 1200°C for Nimonic 75), which is critical for hot working processes during nut manufacturing.

Elevated Temperature Capabilities

Exceptional Corrosion Resistance of Nimonic Nuts

Nimonic alloys offer outstanding corrosion resistance in high-temperature oxidizing environments, making them suitable for the most demanding applications in gas turbines, aerospace, and industrial processing. The chromium content (18-21%) provides excellent oxidation resistance by forming a protective Cr₂O₃ layer at elevated temperatures. Cobalt additions in Nimonic 90 enhance hot corrosion resistance and stability during long-term operation at high temperatures. All three alloys exhibit good resistance to scaling and oxidation under continuous exposure. Nimonic 90 meets NACE MR0175 / ISO 15156-3 requirements for sour service applications in oil and gas. Nimonic 75 is specifically designed for applications requiring oxidation and scaling resistance at high operating temperatures up to 1050°C.

• Oxidation Resistance: Outstanding resistance to scaling and oxidation up to 1050°C under continuous exposure. Forms protective oxides (Cr₂O₃, Al₂O₃, TiO₂) that provide excellent high-temperature corrosion resistance. Nimonic 75 is specifically designed for applications requiring oxidation and scaling resistance up to 1050°C.
• Hot Corrosion: Good resistance to hot corrosion in combustion environments. Nimonic 90 is designed to operate in hot gas zones where long-term thermal stability is required, with high resistance to hot oxidation allowing use in engine applications. Nimonic 80A has good corrosion and oxidation resistance and high tensile properties at temperatures to 815°C.
• Sulfidation Resistance: Nimonic alloys perform well in sulfur-containing environments, with Nimonic 90 meeting NACE MR0175 / ISO 15156-3 requirements for sour service in oil and gas applications.
• Salt Spray Environments: Performs well in salt spray environments found in marine gas turbine service and naval applications.
• Solution Treated Condition: Solution treated material offers good corrosion resistance and fabricability for custom nut manufacturing.
• Bimetallic Corrosion: Can be safely connected to other nickel-based superalloys, stainless steels, and titanium alloys with appropriate precautions. Silver-plated nuts (AMS 2410) reduce galvanic corrosion risk and provide anti-seize properties at elevated temperatures.

Manufacturing Standards – Nimonic Nuts

All Nimonic nuts are manufactured and tested to meet the following standards:

We offer surface finishes: plain (as-machined), chemical cleaned, passivated. Silver plating per AMS 2410 available for anti‑seize and enhanced conductivity – recommended for aerospace self-locking nuts in high-temperature applications. Controlled solution and precipitation heat treatment processes per BS HR2 and AMS specifications ensure optimal mechanical properties. Standard heat treatment for Nimonic 90 includes solution treatment at 1080°C (1975°F) followed by rapid cooling, and precipitation hardening at 700-750°C (1290-1380°F) for 16 hours with air cooling. For Nimonic 80A, solution treatment at 1080°C followed by age hardening at 700°C for 16 hours. NADCAP accredited heat treatment processes. Specialized machining, tapping, and thread rolling for accurate nut geometry with Class 2B/3B/6H thread fit. 100% inspection available including proof load testing, dimensional inspection, and non-destructive examination. Full traceability and destructive/non‑destructive testing available (UT, FPI, MPI). AS9100 and ISO 9001:2015 certified quality management. ISO 13485 certified for medical applications with cleanroom packaging available. Build-to-print specials to customer specifications are available.