Nickel Alloy Ni-Span-C 902-ANN (Annealed)
Heat-treated state · default condition
UNS N09902
Softest condition, supplied for deep drawing, coiling and forming of diaphragms and springs before ageing.
Values for the ANN condition
Other Ni-Span-C 902 tempers and conditions
Ni-Span-C 902 is listed in 7 conditions; see the grade overview at Ni-Span-C 902.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefaultThis page 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-ANN?
Ni-Span-C 902-ANN is Ni-Span-C 902 heat treated to ANN — softest condition, supplied for deep drawing, coiling and forming of diaphragms and springs before ageing. Ni-Span-C 902-ANN 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). Ni-Span-C 902-ANN 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).
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-ANN properties
Typical room-temperature values for Ni-Span-C 902-ANN; 12 are specific to this condition. Other listed values are Ni-Span-C 902 reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Ni-Span-C 902-ANN 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-ANN 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-ANN 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-ANN 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-ANN 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-ANN'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. Confirm any required mill or lot documentation when quoting.
Working with Ni-Span-C 902-ANN
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.
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.
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 | — |
Ni-Span-C 902-ANN — frequently asked
What is Ni-Span-C 902-ANN used for?
Ni-Span-C 902-ANN 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-ANN?
Ni-Span-C 902-ANN 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-ANN 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-ANN 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-ANN?
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-ANN 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-ANN?
Ni-Span-C 902-ANN 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.