Nickel Alloy Nimonic 80A STA-HT
Precip hard
UNS N07080 · EN 2.4631, 2.4952 · GB GH4080A
STA-HT = 1080 °C/8 h AC + 850 °C/24 h AC stabilise + 700 °C/16 h AC
Triple heat treatment for turbine blades/rings that see prolonged 750–850 °C service — trades a little room-temperature strength for microstructural stability and creep life.
Values for the STA-HT condition
Other Nimonic 80A tempers and conditions
Nimonic 80A is listed in 5 conditions; see the grade overview at Nimonic 80A.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest supply condition — pick it for machining, deep forming or bending before the customer performs the ageing treatment. | 320 | 800 | 45 | 185 HB | — |
STA-HTThis page 1080 °C/8 h AC + 850 °C/24 h AC stabilise + 700 °C/16 h AC | Triple heat treatment for turbine blades/rings that see prolonged 750–850 °C service — trades a little room-temperature strength for microstructural stability and creep life. | 640 | 1,010 | 30 | 30 HRC | 1.4 % IACS |
STADefault Solution treated and aged | Standard commercial bar/forging condition — the best all-round strength/ductility balance for fasteners, valves and hot tooling to ~815 °C. | 700 | 1,100 | 27 | 33 HRC | — |
Hot forged / hot rolled and precipitation hardened | Valve-head and hot-forged part condition specified by hardness — used for exhaust valves and hot-work punches where a 300–380 HB forged body is required. | 730 | 1,120 | 22 | 36 HRC | 1.4 % IACS |
Cold drawn bar/wire, then aged 700 °C/16 h | Highest-strength small-section product (bolts, springs, wire) — cold work plus ageing raises strength but ductility and weldability drop sharply. | 900 | 1,230 | 15 | 38 HRC | — |
What is Nimonic 80A STA-HT?
Nimonic 80A STA-HT is Nimonic 80A in the STA-HT condition — triple heat treatment for turbine blades/rings that see prolonged 750–850 °C service — trades a little room-temperature strength for microstructural stability and creep life. Nimonic 80A STA-HT has a yield strength of 640 MPa (92.8 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 81% of nickel alloy grades. Elongation at break is 30% and the elastic modulus is 222 GPa (32.2 Msi). Nimonic 80A STA-HT has a density of 8.19 g/cm³ (0.296 lb/in³), lighter than 68% of nickel alloy grades. It melts at 1,360°C (2,480 °F). STA is the default condition FabDigit quotes; STA-HT is available on request or by drawing note.
Advantages
- High strength — 640 MPa (92.8 ksi), better than 81% of nickel alloy grades
Limitations
- Difficult to weld — 32/100, worse than 77% of nickel alloy grades
Nimonic 80A STA-HT properties
Typical room-temperature values for Nimonic 80A STA-HT; 22 are specific to this condition. Other listed values are Nimonic 80A reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Nimonic 80A STA-HT has a density of 8.19 g/cm³ (0.296 lb/in³), lighter than 68% of nickel alloy grades. It melts at 1,360°C (2,480 °F).
Mechanical15
Nimonic 80A STA-HT has a yield strength of 640 MPa (92.8 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 81% of nickel alloy grades. Elongation at break is 30% and the elastic modulus is 222 GPa (32.2 Msi).
Thermal6
Nimonic 80A STA-HT is rated for continuous service to 870°C (1,598 °F). It conducts heat at 11.2 W/m·K (6.47 BTU/hr·ft·°F), worse than 52% of nickel alloy grades. Thermal expansion is 12.7 µm/m·K (7.06 µin/in·°F).
Electrical3
Nimonic 80A STA-HT conducts electricity at 1.4 % IACS, worse than 65% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (76/100), worse than 59% of nickel alloy grades.
Sustainability4
Producing a kilogram of Nimonic 80A STA-HT takes about 200 MJ of energy and emits 13.5 kg of CO₂ — more than 78% of nickel alloy grades. Typical recycled content is 35%.
Manufacturability6
Nimonic 80A STA-HT's machinability is poor (16/100, worse than 71% of nickel alloy grades); weldability poor (32/100); formability poor (33/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Nimonic 80A STA-HT
Is Nimonic 80A easy to machine?
Machine preferably in the solution-treated state with rigid setups, positive-rake carbide or ceramic tooling, low speed/heavy feed and flood coolant; never dwell — the alloy work-hardens instantly and glazes the cut.
Can Nimonic 80A be welded?
GTAW/EB weld in the solution-treated condition using matching or Ni-Cr-Ti filler, low heat input and no interpass overheating, then re-solution and age; direct welding of aged material risks strain-age (γ′ reheat) cracking.
Can Nimonic 80A be formed, bent or molded?
Hot work at 1050–1150 °C with frequent reheats; cold forming only from the annealed condition with heavy tooling and interstage anneals at 1080 °C due to the very high work-hardening rate.
What surface finishes work on Nimonic 80A?
Grit-blast or pickle in HNO₃-HF to remove the tenacious Cr/Ti/Al oxide before brazing, plating or NDT; it takes a good mechanical polish, and no anodizing applies (n/a for Ni alloys).
Nimonic 80A 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 |
|---|---|---|
| Cr | 18 – 21 | 19.5 |
| Tiγ′ former | 1.8 – 2.7 | 2.4 |
| Alγ′ former | 1 – 1.8 | 1.4 |
| Fe | ≤ 3 | 1 |
| Co | ≤ 2 | 0.5 |
| Mn | ≤ 1 | 0.3 |
| Si | ≤ 1 | 0.3 |
| C | ≤ 0.1 | 0.06 |
| Cu | ≤ 0.2 | 0.05 |
| Zr | ≤ 0.15 | 0.05 |
| B | ≤ 0.01 | 0 |
| S | ≤ 0.02 | 0.01 |
| Nibalance, plus Co counted with Ni in some specs | ≥ 65 (balance) | — |
Nimonic 80A STA-HT — frequently asked
What is Nimonic 80A STA-HT used for?
Nimonic 80A STA-HT is typically used for turbine blades (early designs), exhaust valves and high-temperature springs and fasteners. In short: classic γ′-hardened Ni-Cr alloy; 815 °C service capability; very low machinability rating.
What is the yield strength of Nimonic 80A STA-HT?
Nimonic 80A STA-HT has a typical yield strength of 640 MPa (92.8 ksi) and a tensile strength of 1,010 MPa (146 ksi) — stronger than 81% of nickel alloy grades. Strength varies by condition: see the 5 listed tempers.
Is Nimonic 80A STA-HT easy to machine?
Not especially — machinability is rated poor (16/100, worse than 71% of nickel alloy grades). Machine preferably in the solution-treated state with rigid setups, positive-rake carbide or ceramic tooling, low speed/heavy feed and flood coolant; never dwell — the alloy work-hardens instantly and glazes the cut.
Can Nimonic 80A STA-HT be welded?
Not readily — weldability is rated poor (32/100). GTAW/EB weld in the solution-treated condition using matching or Ni-Cr-Ti filler, low heat input and no interpass overheating, then re-solution and age; direct welding of aged material risks strain-age (γ′ reheat) cracking.
What surface finishes work on Nimonic 80A STA-HT?
Grit-blast or pickle in HNO₃-HF to remove the tenacious Cr/Ti/Al oxide before brazing, plating or NDT; it takes a good mechanical polish, and no anodizing applies (n/a for Ni alloys).
Can Nimonic 80A STA-HT be formed, bent or molded?
Hot work at 1050–1150 °C with frequent reheats; cold forming only from the annealed condition with heavy tooling and interstage anneals at 1080 °C due to the very high work-hardening rate.
What is the maximum service temperature of Nimonic 80A STA-HT?
Nimonic 80A STA-HT is rated for continuous use to about 870°C (1,598 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Nimonic 80A-STA and Nimonic 80A-ST?
STA is the default condition — standard commercial bar/forging condition — the best all-round strength/ductility balance for fasteners, valves and hot tooling to ~815 °C. ST: softest supply condition — pick it for machining, deep forming or bending before the customer performs the ageing treatment. Yield strength is 700 MPa in STA versus 320 MPa in ST.
Sources
- NIMONIC alloy 80A technical bulletin — Special Metals Corporation (2004)
- BS 3076 / HR 1 – Nickel and nickel alloy bar (NA20) — BSI (1989)
- EN 10090 Valve steels and alloys for internal combustion engines (NiCr20TiAl, 2.4952) — CEN (1998)
- GB/T 14992 / GH4080A high-temperature alloy designations — SAC (2005)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Superalloys: A Technical Guide, 2nd ed. — ASM International (2002)
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.