⚡ Quick Specs: Nimonic 75
What Is Nimonic 75?
Nimonic 75 (UNS N06075 / W.Nr. 2.4951) is an 80/20 nickel-chromium solid-solution alloy with small additions of titanium and carbon. As the original alloy in the Nimonic series — first developed in the 1940s — it established the Ni-Cr platform that later precipitation-hardened superalloys would build upon.
Unlike later Nimonic grades that rely on gamma-prime precipitation for strength, Nimonic 75 derives its properties from a simple solid-solution matrix with chromium carbide dispersion. This gives it excellent oxidation resistance up to 1050°C, good ductility and fabricability, and reliable long-term service in furnace and heat treatment applications. As a Nimonic 75 manufacturer and supplier, Hangbo Alloy Group stocks the grade in sheet, plate, bar, wire, and fabricated component forms.
Chemical Composition
Nominal composition of Nimonic 75 per UNS N06075. All values in weight percent (wt%).
| Element | Min (wt%) | Max (wt%) |
|---|---|---|
| Nickel (Ni) | Balance | ~75.0 |
| Chromium (Cr) | 18.0 | 21.0 |
| Iron (Fe) | — | 5.0 |
| Titanium (Ti) | 0.20 | 0.60 |
| Carbon (C) | 0.08 | 0.15 |
| Manganese (Mn) | — | 1.0 |
| Silicon (Si) | — | 1.0 |
| Copper (Cu) | — | 0.50 |
| Sulfur (S) | — | 0.015 |
Physical Properties
| Property | Value | Unit |
|---|---|---|
| Density | 8.37 | g/cm³ |
| Melting Range | 1340 – 1380 | °C |
| Specific Heat (20 °C) | 460 | J/kg·K |
| Thermal Conductivity (20 °C) | 13.5 | W/m·K |
| Electrical Resistivity (20 °C) | 1.10 | μΩ·m |
| Young's Modulus (20 °C) | 215 | GPa |
| Mean CTE (20–100 °C) | 12.9 | μm/m·°C |
Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength (Rm, annealed) | 600 – 850 MPa |
| Yield Strength (Rp0.2, annealed) | 240 – 400 MPa |
| Elongation (A%, annealed) | 30 – 45% |
| Hardness (annealed) | 85 – 95 HRB |
| Shear Modulus | ~82 GPa |
High-Temperature Performance
- Oxidation resistance: Forms a protective chromium oxide (Cr₂O₃) scale in air and combustion gases up to 1050°C, with useful life in cyclic heating conditions.
- Carburization resistance: The high nickel content provides good resistance to carbon absorption in reducing atmospheres at elevated temperatures.
- Creep strength: While not as strong as precipitation-hardened grades, Nimonic 75 offers useful creep-rupture properties to about 800°C, suitable for static furnace components.
- Thermal cycling endurance: The alloy tolerates repeated heating/cooling cycles without embrittlement, making it ideal for heat treatment baskets and fixtures.
- Sulfur-bearing atmospheres: Good resistance to sulfur attack up to moderate concentrations, suitable for oil-fired furnace environments.
Corrosion Resistance
- High-temperature oxidation: Excellent resistance in air and flue gas environments up to 1050°C. The chromium content forms a stable, adherent oxide scale that resists spalling under thermal cycling.
- Green rot resistance: The balanced Ni-Cr composition avoids the "green rot" phenomenon that affects some nickel-chromium alloys in alternately oxidizing and reducing conditions at 800–1000°C.
- Nitriding resistance: Good resistance to nitrogen absorption in ammonia-based heat treatment atmospheres (nitriding, nitrocarburizing).
- Aqueous corrosion: While designed for high-temperature service, Nimonic 75 provides moderate resistance to general aqueous corrosion similar to other high-nickel alloys.
Applications
| Application Area | Typical Components & Notes |
|---|---|
| Furnace Components | Muffles, retorts, radiant tubes, and heat treatment baskets operating up to 1050°C in air and controlled atmospheres |
| Heat Treatment Fixtures | Jigs, trays, grids, and support frames for carburizing, nitriding, annealing, and brazing furnaces |
| Gas Turbine Combustion | Flame tubes, combustion chambers, transition ducts, and afterburner components in aero and industrial gas turbines |
| Nuclear Engineering | Core support structures, control rod guide tubes, and spacer grids in advanced gas-cooled reactors (AGR) where good oxidation resistance is essential |
| Petrochemical Processing | Catalyst support grids, reactor internals, and reformer tube hangers in high-temperature hydrocarbon service |
| Electrical Heating Elements | Sheath material for mineral-insulated heating cables and cartridge heaters |
Available Product Forms
| Product Form | Typical Dimensions & Specifications |
|---|---|
| Sheet & Plate (AMS 5566) | Thickness 0.5 – 12 mm, hot-rolled or cold-rolled, annealed and descaled |
| Bar & Rod (BS HR 5) | φ 6 – φ 200 mm, hot-finished or cold-drawn, solution annealed |
| Wire (DTD 703B) | φ 0.1 – φ 8.0 mm, spring-temper or annealed, for heating elements and fasteners |
| Forgings | Custom rings, discs, and flanges per customer drawing, solution treated |
| Welded Tube | OD 10 – 114 mm, wall 0.8 – 6 mm, as-welded or bright annealed |
| Fabricated Components | Heat treatment baskets, furnace fixtures, and radiant tubes fabricated to specification |
Heat Treatment
| Step | Temperature | Cooling | Purpose |
|---|---|---|---|
| Softening/Annealing | 1050 – 1100 °C | Air cool or water quench | Fully soften for forming and welding |
| Stress Relieving | 700 – 800 °C | Air cool | Remove residual stresses after cold working or machining |
Related Standards & Specifications
| Standard | Product Scope / Notes |
|---|---|
| UNS | N06075 |
| DIN / W.Nr. | 2.4951 |
| BS HR 5 | Bar and section (UK aerospace) |
| BS HR 504 | Welded tube |
| DTD 703B | Wire |
| AMS 5566 | Sheet, strip, and plate |
| AMS 5765 | Bars, forgings, and rings |
Frequently Asked Questions (FAQ)
1. What is Nimonic 75?
Nimonic 75 (UNS N06075 / W.Nr. 2.4951) is an 80/20 nickel-chromium solid-solution alloy with titanium and carbon additions. It is the original alloy in the Nimonic series, developed in the 1940s for gas turbine combustion chambers. Today it is widely used for furnace components, heat treatment fixtures, and structural parts operating up to 1050°C in oxidizing atmospheres.
2. What is the chemical composition of Nimonic 75?
Nominal Nimonic 75 composition (wt%): Ni balance (~75%), Cr 18.0–21.0, Fe ≤5.0, Ti 0.20–0.60, C 0.08–0.15, Mn ≤1.0, Si ≤1.0, Cu ≤0.50, S ≤0.015. The simple Ni-Cr-Ti-C chemistry provides oxidation resistance through chromium oxide formation and useful high-temperature strength through carbide dispersion.
3. What is the density and melting range of Nimonic 75?
Nimonic 75 has a density of approximately 8.37 g/cm³ (0.302 lb/in³) and a melting range of approximately 1340–1380 °C (2445–2515 °F). Its density is slightly higher than typical stainless steels due to the high nickel content.
4. What are the mechanical properties of Nimonic 75?
In the annealed condition, Nimonic 75 typically delivers tensile strength of 600–850 MPa (87–123 ksi), 0.2% yield strength of 240–400 MPa (35–58 ksi), elongation of 30–45%, and hardness of 85–95 HRB. Cold working can substantially increase strength for spring and fastener applications.
5. What is the maximum service temperature of Nimonic 75?
Nimonic 75 provides useful oxidation resistance up to about 1050°C (1920°F) in air and flue gas environments. For load-bearing applications, the practical maximum is around 800°C (1470°F) where creep strength remains adequate for static furnace components and fixtures.
6. Is Nimonic 75 age-hardenable?
No. Unlike Nimonic 80A, Nimonic 90, or Nimonic 105, Nimonic 75 is a solid-solution strengthened alloy and does not precipitation-harden. Its strength comes from the nickel-chromium matrix and chromium carbide dispersion. Cold working is the only practical method to increase its strength.
7. Can Nimonic 75 be welded?
Yes, Nimonic 75 has excellent weldability for a nickel alloy. It can be joined using GTAW (TIG), GMAW (MIG), and resistance welding processes. Matching or near-matching Ni-Cr filler metals are recommended. Post-weld heat treatment is normally not required for furnace applications, though stress relieving at 700–800°C may be beneficial for heavy sections.
8. What is the difference between Nimonic 75 and Inconel 600?
Both are Ni-Cr solid-solution alloys, but Nimonic 75 has a higher Ni:Cr ratio (~80:20) versus Inconel 600 (~75:15.5). Nimonic 75 also contains intentional titanium (0.2–0.6%) and slightly higher carbon (0.08–0.15%) for carbide dispersion strengthening. This gives Nimonic 75 better high-temperature strength and oxidation resistance, while Inconel 600 offers broader aqueous corrosion resistance.
9. What product forms are available for Nimonic 75?
Hangbo Alloy supplies Nimonic 75 in sheet, plate, bar, rod, wire, welded tube, forgings, and custom fabricated furnace components. Common specifications include BS HR 5 (bar), DTD 703B (wire), and AMS 5566 (sheet/plate).
10. What are typical applications of Nimonic 75?
Primary applications include furnace muffles, retorts, and radiant tubes; heat treatment baskets, trays, and jigs; gas turbine flame tubes and combustion chambers; nuclear reactor core supports (AGR); petrochemical catalyst grids and reformer hangers; and mineral-insulated heating cable sheaths.
11. How does Nimonic 75 resist green rot?
Green rot is intergranular oxidation of chromium that occurs in some Ni-Cr alloys when cycled between oxidizing and reducing conditions at 800–1000°C. Nimonic 75 resists this through its balanced 80/20 Ni-Cr ratio and controlled titanium addition, which promotes a more stable chromium oxide scale that is less susceptible to alternating atmosphere attack.
12. How much does Nimonic 75 cost and what is the lead time?
Nimonic 75 is among the more economical nickel alloys, typically priced lower than precipitation-hardened Nimonic grades and well below cobalt-based superalloys. Standard mill products (sheet, plate, bar) are normally available from stock or with 2–4 week lead times. Custom fabricated furnace components require engineering review; contact Hangbo Alloy at hangbo@nickel-alloy.com for a current quote.
Need Nimonic 75 for Furnace Components or High-Temperature Service?
Hangbo Alloy Group is a trusted global manufacturer and supplier of Nimonic 75 (UNS N06075 / 2.4951) in sheet, plate, bar, wire, and fabrications. Mill test certificates to EN 10204 3.1, full traceability, and competitive pricing on every order.