Table of Contents
Nimonic 90 is a precipitation-hardenable nickel-chromium-cobalt alloy that offers excellent high-temperature strength, oxidation resistance, and thermal stability, making it an ideal choice for manufacturing springs used in extreme environments such as aerospace, nuclear, and chemical processing. This article explores the composition, mechanical properties, processing, applications, and technical standards relevant to Nimonic 90 springs.
Chemical Composition of Nimonic 90
The superior performance of Nimonic 90 springs is due to the alloy's well-balanced chemical composition. The presence of titanium and aluminum enables age hardening, while chromium enhances oxidation resistance.
| Element | Percentage (%) |
|---|---|
| Nickel (Ni) | Balance |
| Chromium (Cr) | 18.0–21.0 |
| Cobalt (Co) | 15.0–21.0 |
| Iron (Fe) | 1.5 max |
| Titanium (Ti) | 2.0–3.0 |
| Aluminum (Al) | 1.0–2.0 |
| Carbon (C) | 0.13 max |
| Silicon (Si) | 1.0 max |
| Manganese (Mn) | 1.0 max |
| Zirconium (Zr) | 0.02–0.10 |
Mechanical Properties of Nimonic 90 Springs
Nimonic 90 springs are engineered to perform under high temperatures and loads. The alloy retains excellent mechanical properties up to around 950°C.
| Property | Value |
|---|---|
| Density | 8.18 g/cm³ |
| Tensile Strength (at room temp) | 965 MPa (min) |
| Yield Strength (0.2% offset) | 690 MPa (min) |
| Elongation | 20% (min) |
| Hardness (Vickers) | 250–350 HV |
| Operating Temperature Range | Up to 950°C |
Spring Characteristics and Benefits
Nimonic 90 springs are known for their resistance to high-temperature relaxation, creep resistance, and thermal fatigue strength. These characteristics are essential for springs used in turbine engines, valves, and high-pressure systems.
| Feature | Description |
|---|---|
| Relaxation Resistance | Excellent at elevated temperatures, ensuring long service life |
| High Load Capacity | Supports significant mechanical loads without deformation |
| Oxidation Resistance | Performs in oxidizing atmospheres up to 950°C |
| Fatigue Strength | Superior under cyclic thermal and mechanical loading |
Heat Treatment and Fabrication
The performance of Nimonic 90 springs can be enhanced through proper heat treatment and careful forming techniques. Springs are typically manufactured using wire or strip forms, then heat-treated for optimal properties.
Solution Annealing: Performed at 1080°C followed by air cooling. This step dissolves precipitates and prepares the material for aging.
Aging Treatment: Conducted at 700–850°C for 16–24 hours to develop full mechanical strength through gamma prime precipitation.
Forming: Springs can be formed through cold coiling followed by stress relief annealing. Special tooling and lubricants are used due to the alloy's strength.
Common Applications of Nimonic 90 Springs
Springs made from Nimonic 90 are utilized in critical high-temperature systems where standard stainless steel springs would fail. These include:
| Application | Details |
|---|---|
| Gas Turbines | Retains strength and form in hot sections like seals and valves |
| Jet Engines | Used in spring-loaded components exposed to extreme thrust and heat |
| Nuclear Reactors | Withstands radiation and thermal cycling in control systems |
| Chemical Processing | Provides reliable tension and compression in corrosive environments |
Standards and Forms Available
Nimonic 90 spring materials are supplied in compliance with international standards, ensuring consistent performance and compatibility across industries.
| Standard | Specification |
|---|---|
| BS HR1 | Bar, rod and wire for springs |
| AMS 5829 | Wire and strip for aerospace applications |
| UNS N07090 | Unified Numbering System designation |
| EN 10095 | Heat-resisting steel and nickel alloy grades |
Dimensional Range for Spring Stock
Spring wire and strip are manufactured to tight tolerances, allowing precise coil and leaf spring production.
| Form | Size Range |
|---|---|
| Round Wire | 0.20 mm to 10 mm diameter |
| Flat Strip | 0.05 mm to 3 mm thickness |
Related Questions
What are the temperature limits for Nimonic 90 springs?
Nimonic 90 springs can operate effectively up to 950°C, making them suitable for turbine and high-heat environments.
Why is Nimonic 90 preferred for aerospace springs?
Its exceptional strength, oxidation resistance, and stability at elevated temperatures make it ideal for aerospace applications like jet engines and turbines.
What are the key standards for Nimonic 90 spring materials?
Common standards include AMS 5829 for aerospace wire, BS HR1 for spring rods, and UNS N07090 as its international designation.