Nickel Alloy Ni-Span-C 902
UNS N09902
Ni-Span-C 902 (N09902) is an age-hardenable Fe-Ni-Cr controlled-expansion alloy containing titanium and aluminium, formulated to hold a nearly constant modulus of elasticity across a wide temperature range for precision springs and resonant elements.
Reference datasheet — Ni-Span-C 902 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
Ni-Span-C 902 tempers and conditions
Ni-Span-C 902 is supplied in 7 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Softest condition, supplied for deep drawing, coiling and forming of diaphragms and springs before ageing. | 310 | 690 | 45 | 165 HB | — |
Hot Finished / Hot Rolled bar and forgings, unaged | As-supplied condition for larger bar and forgings that will be machined and then solution treated plus aged. | 480 | 830 | 30 | 14 HRC | 1.7 % IACS |
Hot Finished + Solution Treated + Aged bar/forging | Hardened bar/forging condition for machined transducer bodies, load cells and mechanical resonators. | 655 | 1,000 | 22 | 31 HRC | 1.8 % IACS |
Annealed + Aged | Standard hardened condition for formed diaphragms and bellows; gives the near-zero thermoelastic coefficient with moderate strength. | 690 | 1,035 | 25 | 32 HRC | — |
Cold drawn | Mill-hardened wire, strip and bar supplied for coiling or stamping followed by a customer ageing cycle. | 930 | 1,100 | 8 | 33 HRC | 1.7 % IACS |
Cold Drawn (≈20–40 %) + Aged | Usual finished condition for hairsprings, precision coil springs and Bourdon tubes — high strength plus flat modulus. | 1,200 | 1,400 | 8 | 41 HRC | — |
Heavily Cold Drawn (≈50 %) + Aged | Maximum-strength temper for fine spring wire and high-stress resonant elements; ductility is minimal. | 1,400 | 1,590 | 5 | 45 HRC | 1.8 % IACS |
What is Ni-Span-C 902?
Ni-Span-C 902 (N09902) is an age-hardenable Fe-Ni-Cr controlled-expansion alloy containing titanium and aluminium, formulated to hold a nearly constant modulus of elasticity across a wide temperature range for precision springs and resonant elements. In the annealed condition it gives about 310 MPa yield, 690 MPa tensile, 45% elongation and 165 HB (85 HRB) with an elastic modulus of 179 GPa; strength is raised by ageing, and stock is available annealed, cold-drawn, hot-finished and cold-worked with or without ageing. Maximum service temperature is 200 °C, machinability is poor (rated 30) and weldability is only moderate (rated 55) because of the Ti/Al content. Alloy 42 or Alloy 52 is the alternative when the requirement is a glass expansion match rather than constant modulus. Ni-Span-C 902 has a density of 8.05 g/cm³ (0.291 lb/in³), lighter than 83% of nickel alloy grades. It melts at 1,425°C (2,597 °F). Ni-Span-C 902 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 74% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 179 GPa (26 Msi).
What is Ni-Span-C 902 used for?
- precision springs
- tuning forks
- gyroscope flexures
- seismic and pressure sensor elements
Advantages
- Low embodied carbon — 8 kg CO₂/kg, better than 93% of nickel alloy grades
- Easy to machine — 30/100, better than 90% of nickel alloy grades
- Conducts heat well — 13.8 W/m·K (7.97 BTU/hr·ft·°F), better than 76% of nickel alloy grades
- High electrical conductivity — 1.7 % IACS, better than 76% of nickel alloy grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 100% of nickel alloy grades
- Needs corrosion protection — 40/100, worse than 95% of nickel alloy grades
- Low stiffness — 179 GPa (26 Msi), worse than 88% of nickel alloy grades
Ni-Span-C 902 properties
Typical room-temperature values for Ni-Span-C 902-ANN; bars are the position among nickel alloy grades.
Physical3
Ni-Span-C 902 has a density of 8.05 g/cm³ (0.291 lb/in³), lighter than 83% of nickel alloy grades. It melts at 1,425°C (2,597 °F).
Mechanical13
Ni-Span-C 902 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 74% of nickel alloy grades. Elongation at break is 45% and the elastic modulus is 179 GPa (26 Msi).
Thermal6
Ni-Span-C 902 is rated for continuous service to 200°C (392 °F). It conducts heat at 13.8 W/m·K (7.97 BTU/hr·ft·°F), better than 76% of nickel alloy grades. Thermal expansion is 8 µm/m·K (4.44 µin/in·°F).
Electrical3
Ni-Span-C 902 conducts electricity at 1.7 % IACS, better than 76% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 95% of nickel alloy grades.
Sustainability4
Producing a kilogram of Ni-Span-C 902 takes about 115 MJ of energy and emits 8 kg of CO₂ — less than 91% of nickel alloy grades. Typical recycled content is 25%.
Manufacturability8
Ni-Span-C 902's machinability is poor (30/100, better than 90% of nickel alloy grades); weldability good (55/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the nickel alloy family
Yield strength against density for every nickel alloy grade FabDigit runs. Ni-Span-C 902 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Ni-Span-C 902
Is Ni-Span-C 902 easy to machine?
Machine in the annealed or solution-treated state with sharp, rigid, positive-rake carbide tooling, slow speeds (~15–25 m/min) and heavy sulphurised coolant; the aged alloy is gummy and work-hardens rapidly, so grind rather than turn tight tolerances after ageing.
Can Ni-Span-C 902 be welded?
GTAW, EBW, laser and resistance welding are used with matching or Ni-Cr filler under good gas shielding; the Ti/Al content makes the alloy hot-crack and oxide sensitive, so weld in the annealed state, keep heat input low and re-solution/re-age afterwards to restore the constant modulus.
Can Ni-Span-C 902 be formed, bent or molded?
Form, coil, draw and deep-draw in the annealed temper (it work-hardens quickly, so interstage anneals at ~955–1010 °C are common); age formed parts in a fixture 4–8 h at 650–730 °C to set shape, strength and near-zero thermoelastic coefficient.
Ni-Span-C 902 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| NiNi+Co | 41 – 43.5 | 42.25 |
| Cr | 4.9 – 5.75 | 5.3 |
| Tiprincipal hardener (γ′) | 2.2 – 2.75 | 2.45 |
| Al | 0.3 – 0.8 | 0.55 |
| C | ≤ 0.06 | 0.03 |
| Mn | ≤ 0.8 | 0.4 |
| Si | ≤ 1 | 0.5 |
| Cu | ≤ 0.5 | 0.05 |
| S | ≤ 0.04 | 0.01 |
| P | ≤ 0.04 | 0.01 |
| Febalance, ~48–50 % | balance |
What surface finishes work on Ni-Span-C 902?
Descale in molten salt or pickle after annealing to remove tenacious Ti/Al oxide; not anodizable — protect exposed springs with passivation plus electroless nickel, thin gold or chromate/oil, and abrasive-polish or lap resonant surfaces before ageing.
Surface treatments FabDigit runs on nickel alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Nickel Alloy Ni-Span-C 902 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N09902
How much does Ni-Span-C 902 cost?
Ni-Span-C 902 is a high-cost nickel alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Ni-Span-C 902 — frequently asked
What is Ni-Span-C 902 used for?
Ni-Span-C 902 is typically used for precision springs, tuning forks, gyroscope flexures and seismic and pressure sensor elements. In short: constant modulus over temperature; age-hardenable spring alloy; sensor and flexure grade.
What is the yield strength of Ni-Span-C 902?
Ni-Span-C 902 has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 74% of nickel alloy grades. Strength varies by condition: see the 7 listed tempers.
Is Ni-Span-C 902 easy to machine?
Not especially — machinability is rated poor (30/100, better than 90% of nickel alloy grades). Machine in the annealed or solution-treated state with sharp, rigid, positive-rake carbide tooling, slow speeds (~15–25 m/min) and heavy sulphurised coolant; the aged alloy is gummy and work-hardens rapidly, so grind rather than turn tight tolerances after ageing.
Can Ni-Span-C 902 be welded?
Yes — weldability is rated good (55/100). GTAW, EBW, laser and resistance welding are used with matching or Ni-Cr filler under good gas shielding; the Ti/Al content makes the alloy hot-crack and oxide sensitive, so weld in the annealed state, keep heat input low and re-solution/re-age afterwards to restore the constant modulus.
What surface finishes work on Ni-Span-C 902?
Descale in molten salt or pickle after annealing to remove tenacious Ti/Al oxide; not anodizable — protect exposed springs with passivation plus electroless nickel, thin gold or chromate/oil, and abrasive-polish or lap resonant surfaces before ageing.
Can Ni-Span-C 902 be formed, bent or molded?
Form, coil, draw and deep-draw in the annealed temper (it work-hardens quickly, so interstage anneals at ~955–1010 °C are common); age formed parts in a fixture 4–8 h at 650–730 °C to set shape, strength and near-zero thermoelastic coefficient.
What is the maximum service temperature of Ni-Span-C 902?
Ni-Span-C 902 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Ni-Span-C 902-ANN and Ni-Span-C 902-CD?
ANN is the default condition — softest condition, supplied for deep drawing, coiling and forming of diaphragms and springs before ageing. CD: mill-hardened wire, strip and bar supplied for coiling or stamping followed by a customer ageing cycle. Yield strength is 310 MPa in ANN versus 930 MPa in CD.
How much does Ni-Span-C 902 cost?
Ni-Span-C 902 is a high-cost nickel alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Ni-Span-C alloy 902 technical bulletin — Special Metals Corporation (2004)
- AMS 5221 / AMS 5223 / AMS 5225 — Alloy 42Ni-5Cr-2.4Ti sheet, strip, bar and wire — SAE International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (constant-modulus alloys) — ASM International (1990)
- ASM Specialty Handbook: Nickel, Cobalt and Their Alloys — ASM International (2000)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.