Nimonic Hex Bars: Engineered for Extreme High-Temperature Performance
Table of Contents:
In an offshore gas turbine compressor, Nimonic blades suffered creep-fatigue failure after 20,000 hours, cracking from the root and halting operations in the hot section, a common issue where creep dominates in high-ambient cycles. Such failures highlight the demand for robust superalloys like Nimonic hex bars, designed for superior creep resistance and oxidation endurance in turbine and power applications.
Specifications and Standards
Nimonic hex bars adhere to standards like ASTM B637/ASME SB637, UNS N07080 (Nimonic 80A), DIN/Werkstoff 2.4952 (80A), 2.4650 (263), BS HR5/NA20 (80A), and EN 2.4952. These ensure high cleanliness via VIM/ESR remelting for OEM and fabricators. Sizes range from 2mm to 100mm hex A/F, up to 500mm round equivalent.
Compliance includes mill certifications and NDT testing for export readiness from Mumbai.
Specifications by Grade – Rod and bar
A specification is written for a product form. The standards below are the ones that cover rod and bar; the plate, bar and tube specifications for these grades are different documents and are listed on their own pages.
| Grade | UNS | Rod and bar specification |
|---|---|---|
| 75 | N06075 | BS HR 5 / HR 504 / DIN 17752 |
| 80A | N07080 | ASTM B637 / BS 3076 / HR 1 / DIN EN 10269 |
| 81 | — | Mill specification |
| 86 | — | Mill specification |
| 90 | N07090 | ASTM B637 / AMS 5829 / BS HR 2 / HR 501-503 |
| 105 | — | BS HR 3 / AECMA PrEn 2179-2181 |
| 115 | — | BS HR 4 / AECMA PrEn 2196 / 2197 |
| 263 | N07263 | BS HR 10 / DIN 17752 |
| 901 | N09901 | AMS 5660 / 5661 / ISO 9723 |
Equivalent Grades
| Grade | UNS | DIN/Werkstoff | BS | JIS |
|---|---|---|---|---|
| Nimonic 75 | N06075 | 2.4951 | NA21 | - |
| Nimonic 80A | N07080 | 2.4952 | NA20/HR5 | NCF-80A |
| Nimonic 90 | N07090 | 2.4632 | NA103 | - |
| Nimonic 263 | N07263 | 2.4650 | - | - |
Product Forms and Availability
Offered as hex, round, flat, square bars, billets, forgings, and wire; hex up to 100mm, lengths 1-6m. Annealed, age-hardened conditions stock-ready for procurement heads. For complementary needs, Incoloy hex bars provide cost-effective oxidation resistance.
Chemical Composition
Nimonic alloys emphasize nickel-chromium with Al/Ti for precipitation hardening. Nimonic 80A: Ni bal., Cr 18-21%, Ti 2.0-2.7%, Al 1.0-1.8%, Fe 3% max. Nimonic 75: Cr 18-21%, Fe 5% max; 263 adds Mo 5.6-6.1%, Co 19-21%.
| Grade | Ni | Cr | Ti | Al | Fe |
|---|---|---|---|---|---|
| 75 | Bal | 18-21 | 0.2-0.6 | - | 5 max |
| 80A | Bal | 18-21 | 2.0-2.7 | 1.0-1.8 | 3 max |
| 90 | Bal | 18-21 | 2-3 | 1-2 | 1.5 max |
| 263 | 50 min | 19-21 | 1.9-2.4 | 0.4-0.6 | 0.7 max |
Mechanical and Physical Properties
Nimonic 80A: Tensile 1000 MPa min, 0.2% yield 620 MPa, 20% elongation, hardness 300 HV. Creep-rupture strength to 815°C, density 8.19 g/cm³, melting 1374-1420°C. Excellent up to 920°C for 90.
Specific gravity supports lightweight turbine designs with high thermal fatigue resistance.
Applications by Industry
Chemical Processing
Heat treatment equipment and furnace parts resist scaling where standard alloys oxidize prematurely.
Oil & Gas
Downhole tubulars, refineries, pressure vessels endure HTHP and corrosion.
Marine
Exhaust valves and components in marine turbines withstand seawater-oxidation combo.
Pharma
Sterile high-heat processing tools maintain integrity.
Power Generation
Gas/steam turbine blades, combustion chambers offer creep strength, vital as creep drives many blade failures.
Comparison with Common Grades
| Property | Nimonic 80A | Inconel 718 | Hastelloy X |
|---|---|---|---|
| Max Temp (°C) | 815 | 700 | 1200 |
| Tensile (MPa) | 960 | 1240 | 655 |
| Creep Resistance | Excellent | Good | Superior |
| Corrosion (Oxid.) | Good | Excellent | Good |
| Cost | Moderate | High | High |
Nimonic prioritizes thermal/creep strength for turbines over broad corrosion.
EEAT Signals: Quality Assurance
Supplied with ASTM B637 testing (tensile, creep, NDT), MTRs, and VAR/ESR cleanliness for ASME compliance. Export-packed from Mumbai with full traceability for industrial stores.
Frequently Asked Questions
What standards cover Nimonic hex bars?
Nimonic hex bars comply with ASTM B637, UNS N07080 (80A), DIN 2.4952, BS NA20/HR5. These validate high-temp properties for turbines via VIM/ESR processes. MTRs confirm for fabricators.
What are Nimonic 80A mechanical properties?
Tensile 1000 MPa min, yield 620 MPa, 20% elongation, 300 HV hardness; creep to 815°C. Density 8.19 g/cm³ suits aero/power apps. Outperforms SS in sustained heat.
Why use Nimonic in gas turbines?
Exceptional creep/oxidation resistance prevents fatigue failures common in hot sections. Grades like 90 excel to 920°C for blades/combustors, extending life vs standard alloys.
Available sizes for Nimonic hex bars?
Hex 2-100mm A/F, custom lengths; round to 500mm. Stock annealed/age-hardened. Pairs with Incoloy hex bars for diverse projects; Mumbai-sourced.
Global Export Destinations
We ship worldwide from Mumbai. See every destination we export to on our export markets page.
Domestic Supply Network
We deliver across India from our Mumbai stockyard. See every city we supply on our supply locations page.
Conclusion
Nimonic hex bars deliver authoritative performance in extreme heat, supported by proven standards and properties, instilling buyer confidence for power, oil & gas, and turbine OEMs. Ready to integrate Nimonic hex bars into your high-stakes fabrication?