During a refinery turnaround, aging steel valves continually succumbed to thermal cycling and aggressive acids until engineers specified Nimonic 81 Round Bars. After switching, the newly fabricated bars performed flawlessly through surges, shutdowns, and corrosive attacks propelling a domino effect as procurement teams in chemical, oil & gas, marine, pharma, and power industries adopted this high-chromium superalloy for its uninterrupted performance in extreme operational cycles.
Table of Contents:
Nimonic 81 is a precipitation-hardened nickel-chromium alloy, reinforced with titanium and aluminum. Its advanced formula provides not only high strength but unrivaled resistance to thermal fatigue and hot corrosion, especially where repeated heat-up/cool-down and chemical aggressors threaten equipment longevity. With an ultimate tensile strength around 874 MPa and strength retention at temperatures above 700°C, Nimonic 81 excels far beyond conventional stainless steels or most nickel alloys in process plants, turbines, and engine environments.
Round bars are available in sizes from 3mm up to 350mm diameter, in as-forged, cold-drawn, polished, or ground finish to meet every OEM and plant overhaul requirement. Supplied to Special Metals’ proprietary specification, they are supplied with mill tests, ISO 15156 NACE certification for sour service, and dimensional traceability worldwide. Reliable distributors of Nimonic 81 Round Bars back tight project deadlines with ready inventory for fast dispatch in all finishes.
Users in the chemical, marine, and power sectors choose these bars for their stress-rupture reliability, sustained high yield in service, and cost-effective lifecycle performance reducing downtime and emergency shutdowns for critical plant assets.
High-quality Nimonic 81 Round Bars ready for industrial use.
Specification Overview
| Grade | Nimonic 81 |
|---|---|
| Standards | Special Metals proprietary specification for rods and bars; ISO 15156 (NACE MR0175) |
| Diameter Range | 3mm – 350mm |
| Length | 100mm – 6000mm (custom available) |
| Finish | Black, bright, polished, ground, rough-turned |
| Delivery | Stocked, cut-to-order, certified export shipments |
| Price | INR 3,000 – 5,500 per kg. Indicative USD 35 – 65 per kg; quoted against grade, form, size and quantity. |
Equivalent Grades & Standards
| Property | Value |
|---|---|
| UNS number | — |
| Density | 8.06 g/cm3 |
| Melting range | 1305-1375 °C |
| Specific heat (20 °C) | 461 J/kg·°C |
| Thermal conductivity (20 °C) | 10.9 W/m·°C |
| Electrical resistivity (20 °C) | 1.27 µΩ·m |
| Coefficient of expansion (20-100 °C - extruded and stretched bar) | 11.1 µm/m·°C |
| Coefficient of expansion (20-100 °C - cold rolled sheet) | 11.7 µm/m·°C |
| Dynamic modulus of elasticity (20 °C - extruded bar) | 196 GPa |
| Dynamic modulus of elasticity (20 °C - sheet) | 212 GPa |
| Modulus of rigidity (20 °C - dynamic torsional) | 80 GPa |
| Rod and bar specification | Mill specification |
Identifiers and physical constants for Nimonic 81. A dash means no such designation is published for this grade.
Stock & Product Availability
Nimonic 81 round bars are regularly available globally in diverse diameters, surface finishes, and packaging for quick dispatch supporting project and maintenance needs across chemical, oil & gas, marine, pharma, and power sectors.
Chemical Composition
| Element | Min (%) | Max (%) |
|---|---|---|
| Carbon (C) | 0.05 nominal | |
| Silicon (Si) | 0.50 nominal | |
| Copper (Cu) | 0.20 nominal | |
| Iron (Fe) | 1.0 nominal | |
| Manganese (Mn) | 0.50 nominal | |
| Chromium (Cr) | 30.0 nominal | |
| Titanium (Ti) | 1.8 nominal | |
| Aluminium (Al) | 0.9 nominal | |
| Cobalt (Co) | 2.0 nominal | |
| Molybdenum (Mo) | 0.30 nominal | |
| Boron (B) | 0.003 nominal | |
| Zirconium (Zr) | 0.06 nominal | |
| Sulfur (S) | 0.015 nominal | |
| Nickel (Ni) | — | Balance |
Nominal composition for Nimonic 81. These are nominal figures rather than acceptance limits, and they are not measured values for a lot; the mill test certificate supplied with your order states the actual analysis.
Mechanical & Physical Properties
| Property | Typical Value |
|---|---|
| Ultimate Tensile Strength (MPa) | 874 |
| Yield Strength (0.2% MPa) | 565 |
| Elongation (%) | 14 |
| Condition | Cold drawn, ground, annealed |
| Operating Temp (°C) | Up to ~825 (hot corrosion/creep-resistant) |
Applications & Benefits
- Chemical: Reactor lining, pump and valve bars for acid, alkali, and oxidizer handling.
- Marine: Exhaust manifolds, propeller shafts, and engine internals exposed to saltwater and high heat.
- Oil & Gas: Pipeline valves, compressor parts, flanges, and seals for sour/high-pressure wells.
- Pharma: Valves, high-temperature process agitators, and non-corrosive hardware for sterile plants.
- Power: Turbine blades, boiler hardware, and superheater bars for power generation.
- Hardware/Industrial: Wear-resistant fasteners, gears, and pump shafts for multi-sector OEMs.
FAQ & Search Trends
Global Export Destinations
We ship worldwide from Mumbai. See every destination we export to on our export markets page.
Domestic Supply Network Across India
We deliver across India from our Mumbai stockyard. See every city we supply on our supply locations page.
Conclusion
Nimonic 81 Round Bars bring reliability, corrosion resistance, and high-cycle fatigue strength to process, marine, pharma, power, and oil & gas industries backed by UNS, ASTM, and DIN/AMS certification. Will your next upgrade leverage the proven endurance of Nimonic 81?