Nickel Alloy Incoloy 925 STA-120
Precip hard · default condition
UNS N09925
STA-120 = sTA 120 ksi
The standard stocked condition for downhole tools, packers, hangers and fasteners in H₂S service (≤38 HRC per ISO 15156).
Values for the STA-120 condition
Other Incoloy 925 tempers and conditions
Incoloy 925 is listed in 4 conditions; see the grade overview at Incoloy 925.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed (≈1010 °C, rapid cool), non-aged | Softest condition — pick for cold forming, deep drawing, welding of tube/sheet, or as stock to be aged after machining. | 380 | 760 | 45 | 185 HB | — |
STA 110 ksi | Lower-strength aged grade for sour-service parts where maximum toughness and lowest hardness (≤32 HRC) are wanted. | 820 | 1,070 | 30 | 30 HRC | — |
STA-120DefaultThis page STA 120 ksi | The standard stocked condition for downhole tools, packers, hangers and fasteners in H₂S service (≤38 HRC per ISO 15156). | 890 | 1,170 | 26 | 33 HRC | — |
CW+A 140 ksi | Highest strength level, used for high-load fasteners, springs and thin-wall pressure parts; hardness approaches sour-service limits so verify against ISO 15156 envelope. | 1,030 | 1,275 | 20 | 38 HRC | — |
What is Incoloy 925 STA-120?
Incoloy 925 STA-120 is Incoloy 925 in the STA-120 condition — the standard stocked condition for downhole tools, packers, hangers and fasteners in H₂S service (≤38 HRC per ISO 15156). Incoloy 925 STA-120 has a yield strength of 890 MPa (129 ksi) and a tensile strength of 1,170 MPa (170 ksi) — stronger than 93% of nickel alloy grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi). Incoloy 925 STA-120 has a density of 8.08 g/cm³ (0.292 lb/in³), lighter than 81% of nickel alloy grades. It melts at 1,311°C (2,392 °F).
Advantages
- High strength — 890 MPa (129 ksi), better than 93% of nickel alloy grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 75% of nickel alloy grades
Limitations
- Limited service temperature — 540°C (1,004 °F), worse than 75% of nickel alloy grades
Incoloy 925 STA-120 properties
Typical room-temperature values for Incoloy 925 STA-120; 15 are specific to this condition. Other listed values are Incoloy 925 reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Incoloy 925 STA-120 has a density of 8.08 g/cm³ (0.292 lb/in³), lighter than 81% of nickel alloy grades. It melts at 1,311°C (2,392 °F).
Mechanical15
Incoloy 925 STA-120 has a yield strength of 890 MPa (129 ksi) and a tensile strength of 1,170 MPa (170 ksi) — stronger than 93% of nickel alloy grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
Incoloy 925 STA-120 is rated for continuous service to 540°C (1,004 °F). It conducts heat at 11.4 W/m·K (6.59 BTU/hr·ft·°F), better than 53% of nickel alloy grades. Thermal expansion is 12.9 µm/m·K (7.17 µin/in·°F).
Electrical3
Incoloy 925 STA-120 conducts electricity at 1.5 % IACS, better than 59% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 67% of nickel alloy grades.
Sustainability4
Producing a kilogram of Incoloy 925 STA-120 takes about 160 MJ of energy and emits 12 kg of CO₂ — less than 53% of nickel alloy grades. Typical recycled content is 30%.
Manufacturability8
Incoloy 925 STA-120's machinability is poor (20/100, better than 53% of nickel alloy grades); weldability good (55/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Incoloy 925 STA-120
Is Incoloy 925 easy to machine?
Machine in the solution-annealed state where possible; aged material needs rigid setups, positive-rake carbide or ceramic tooling, low speed (15–25 m/min carbide), heavy feed to cut under the work-hardened layer and flood coolant.
Can Incoloy 925 be welded?
GTAW/GMAW with alloy 625, 725 or matching 925 filler, low heat input and no preheat; re-solution + age after welding to restore full strength, and avoid welding in the aged condition for critical parts.
Can Incoloy 925 be formed, bent or molded?
Cold form only in the annealed condition (high work-hardening rate, ~2× the force of 304); hot work 1040–1180 °C with finishing above ~950 °C, then solution anneal and age.
What surface finishes work on Incoloy 925?
Not anodizable — use pickling/passivation, electropolish or mechanical polish; the Cr-rich passive film gives good as-machined corrosion behaviour, and shot peening is common on threaded downhole parts.
Incoloy 925 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 basis in some specs | 42 – 46 | 44 |
| Cr | 19.5 – 22.5 | 21 |
| Mo | 2.5 – 3.5 | 3 |
| Cu | 1.5 – 3 | 2 |
| Tiγ′ former | 1.9 – 2.4 | 2.1 |
| Al | 0.1 – 0.5 | 0.3 |
| Nboptional/residual in some specs | ≤ 0.5 | — |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 0.5 | 0.2 |
| C | ≤ 0.03 | 0.01 |
| S | ≤ 0.03 | 0 |
| P | ≤ 0.03 | 0.01 |
| Feremainder, 22 % min | ≥ 22 (balance) | — |
Incoloy 925 STA-120 — frequently asked
What is Incoloy 925 STA-120 used for?
Incoloy 925 STA-120 is typically used for oilfield fasteners, downhole tools, subsea components and pump/valve shafts. In short: age-hardenable Alloy 825; sour-service high-strength grade; stronger than 825, harder to machine.
What is the yield strength of Incoloy 925 STA-120?
Incoloy 925 STA-120 has a typical yield strength of 890 MPa (129 ksi) and a tensile strength of 1,170 MPa (170 ksi) — stronger than 93% of nickel alloy grades. Strength varies by condition: see the 4 listed tempers.
Is Incoloy 925 STA-120 easy to machine?
Not especially — machinability is rated poor (20/100, better than 53% of nickel alloy grades). Machine in the solution-annealed state where possible; aged material needs rigid setups, positive-rake carbide or ceramic tooling, low speed (15–25 m/min carbide), heavy feed to cut under the work-hardened layer and flood coolant.
Can Incoloy 925 STA-120 be welded?
Yes — weldability is rated good (55/100). GTAW/GMAW with alloy 625, 725 or matching 925 filler, low heat input and no preheat; re-solution + age after welding to restore full strength, and avoid welding in the aged condition for critical parts.
What surface finishes work on Incoloy 925 STA-120?
Not anodizable — use pickling/passivation, electropolish or mechanical polish; the Cr-rich passive film gives good as-machined corrosion behaviour, and shot peening is common on threaded downhole parts.
Can Incoloy 925 STA-120 be formed, bent or molded?
Cold form only in the annealed condition (high work-hardening rate, ~2× the force of 304); hot work 1040–1180 °C with finishing above ~950 °C, then solution anneal and age.
What is the maximum service temperature of Incoloy 925 STA-120?
Incoloy 925 STA-120 is rated for continuous use to about 540°C (1,004 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Incoloy 925 STA-120 and Incoloy 925-SA?
STA-120 is the default condition — the standard stocked condition for downhole tools, packers, hangers and fasteners in H₂S service (≤38 HRC per ISO 15156). SA: softest condition — pick for cold forming, deep drawing, welding of tube/sheet, or as stock to be aged after machining. Yield strength is 890 MPa in STA-120 versus 380 MPa in SA.
Sources
- INCOLOY alloy 925 technical bulletin — Special Metals Corporation (2004)
- ASTM B805 — Precipitation-hardening nickel alloy (UNS N09925) bar, forgings and forging stock for sour service — ASTM International (2018)
- ANSI/NACE MR0175/ISO 15156-3 — Cracking-resistant CRAs for H₂S-containing environments — NACE/ISO (2020)
- API 6ACRA — Age-hardened nickel-based alloys for oil and gas drilling and production equipment — API (2015)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
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.