Nimonic 901 (N09901)

What is Nimonic 901 and its applications?

Nimonic 901 (UNS N09901) is an age-hardenable nickel-iron-chromium superalloy containing molybdenum and titanium. It is used for gas-turbine discs, shafts, rings, casings and seals.

Turbine rotating parts: Discs and shafts with application-specific acceptance.
Engine structures: Rings, casings and related mechanical components.
Turbine sealing systems: Seal components requiring a defined thermal condition.

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Engineering Application & Selection Guide

Solution treatment followed by staged aging develops its precipitation-strengthened condition. The producer specifies a multi-stage treatment for forged bar; this is not a universal instruction for every product geometry or manufacturing route.

Nimonic 901 stud bolts — For turbine-casing enquiries, include the required final condition and material form.
Nimonic 901 hex bolts — For heated supports, assess relaxation, differential expansion and thread-root stresses.
Nimonic 901 socket head cap screws — For restricted-access components, define head geometry, inspection and the assembly lubricant.

Compare 901 and A-286 using matched condition, temperature and design-life data. A generic superiority claim is not a substitution basis. Agree the machining, threading and thermal sequence against the actual product specification.

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Nimonic 901 Composition

Selected nominal composition · wt.%

ElementWeight %

Ni: 42.5%
Cr: 12.5%
Mo: 5.75%
Ti: 2.9%
Al: ≤0.35%
Fe: Balance

ASTM / ASME specifications by product form

Finished-product requirements

Specify the finished-fastener mechanical requirements, condition and inspection separately from the starting-stock specification.

Nimonic 901 hex bolt requirements ↗

Fasteners · dimensional references

Product	Reference
Hex bolts	ISO 4014 / ISO 4017 · ASME B18.2.1
Threaded studs	DIN 976-1 · ASME B18.31.2
Hex nuts	ISO 4032 · ASME B18.2.2
Socket head screws	ISO 4762 · ASME B18.3
Flat washers	ISO 7089 / ISO 7090 · ASME B18.21.1
Custom fasteners	Customer drawing

Raw-material specifications

Product form / scope	Reference
Bar & forgings	AMS 5660 / 5661 · ISO 9723 / 9725

Dimensions do not define material or finished-part compliance. Specify the grade, condition and applicable requirements.

How to specify round bar, plate, wire and strip ↗

Nimonic 901 Physical Properties

Dynamic Young’s modulus and specific heat: producer reference values at 20°C.

Property	Value	Unit
Density	8.14	g/cm³
Dynamic Young’s modulus	201	GPa
Specific heat	431	J/(kg·K)

Temperature curves and values

Nimonic 901 Tensile strength, 0.2% proof stress versus temperature; Vacuum-refined, extruded and forged bar; MPa and degrees Celsius — Tensile and yield strength
Vacuum-refined, extruded and forged bar

Nimonic 901 Elongation, Reduction of area versus temperature; Vacuum-refined, extruded and forged bar; percent and degrees Celsius — Elongation and reduction of area
Vacuum-refined, extruded and forged bar

Procurement and application guide

Specify the material and final condition

State product form, heat treatment and the required strength.

Material forms in the technical reference: Round bar · Flat bar · Forging billet · Extruded sections.

Define the finished-part acceptance

Include the material or bolting specification, required final condition, dimensions and quantity. State the service medium, temperature and loading where known. Agree the required tests, inspection coverage and acceptance criteria for the finished part.

Start with the information you have

Send a drawing or share the product form and dimensions. Identify any undecided requirements for review rather than copying a typical property value into the purchase order.

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