Nickel Alloy Inconel 725
UNS N07725
Inconel 725 (UNS N07725) is a precipitation-hardenable Ni-Cr-Mo alloy, effectively the age-hardenable counterpart of Alloy 625, supplied solution-annealed or in aged conditions (STA-120, STA-150, HF+A, CW+A).
Reference datasheet — Inconel 725 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 STA-120 condition
Inconel 725 tempers and conditions
Inconel 725 is supplied in 5 conditions, soft to hard. STA-120 is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Soft supply condition for forming, machining of complex shapes or welding before final age hardening. | 400 | 830 | 50 | 210 HB | — |
STA-120Default STA 120 ksi | Standard oilfield sour-service condition (API 6ACRA / NACE MR0175, ≤43 HRC) for downhole tools, hangers and valve parts. | 890 | 1,240 | 25 | 35 HRC | — |
Hot finished / forged then directly aged | Cost-saving route for large forgings where controlled hot-work plus direct age gives 120 ksi class properties without a separate solution treatment. | 965 | 1,275 | 22 | 37 HRC | 1.4 % IACS |
STA 150 ksi | Higher-strength aged condition for high-load fasteners, mandrels and setting components where 43 HRC max still applies. | 1,090 | 1,310 | 20 | 40 HRC | — |
Cold worked then aged | Maximum-strength small-section bar and fastener stock; hardness must still be capped for sour service qualification. | 1,200 | 1,400 | 15 | 43 HRC | — |
What is Inconel 725?
Inconel 725 (UNS N07725) is a precipitation-hardenable Ni-Cr-Mo alloy, effectively the age-hardenable counterpart of Alloy 625, supplied solution-annealed or in aged conditions (STA-120, STA-150, HF+A, CW+A). It is chosen for downhole tools and high-strength sour-service fasteners, typically as bar and forgings, delivering 890 MPa yield, 1240 MPa tensile, 25 % elongation, 330 HB (35 HRC) and a corrosion resistance score of 88 in H₂S-bearing brines up to 650 °C. Formability (25) and machinability (14) are poor in the aged state and cost is high; Alloy 718 is the cheaper option where sour-service cracking resistance is not required. Inconel 725 has a density of 8.31 g/cm³ (0.3 lb/in³), heavier than 51% of nickel alloy grades. It melts at 1,271°C (2,320 °F). Inconel 725 has a yield strength of 890 MPa (129 ksi) and a tensile strength of 1,240 MPa (180 ksi) — stronger than 93% of nickel alloy grades. Elongation at break is 25% and the elastic modulus is 204 GPa (29.6 Msi).
What is Inconel 725 used for?
- Oil and gas downhole tools
- High-strength sour-service fasteners
- Subsea wellhead and hanger components
- Valve stems and trim for sour wells
- Packers and landing nipples
- Instrument and completion tubular parts
Advantages
- High strength — 890 MPa (129 ksi), better than 93% of nickel alloy grades
- Good corrosion resistance — 88/100, better than 81% of nickel alloy grades
Limitations
- High embodied carbon — 18 kg CO₂/kg, worse than 98% of nickel alloy grades
Inconel 725 properties
Typical room-temperature values for Inconel 725-STA-120; bars are the position among nickel alloy grades.
Physical3
Inconel 725 has a density of 8.31 g/cm³ (0.3 lb/in³), heavier than 51% of nickel alloy grades. It melts at 1,271°C (2,320 °F).
Mechanical16
Inconel 725 has a yield strength of 890 MPa (129 ksi) and a tensile strength of 1,240 MPa (180 ksi) — stronger than 93% of nickel alloy grades. Elongation at break is 25% and the elastic modulus is 204 GPa (29.6 Msi).
Thermal6
Inconel 725 is rated for continuous service to 650°C (1,202 °F). It conducts heat at 10.8 W/m·K (6.24 BTU/hr·ft·°F), worse than 66% of nickel alloy grades. Thermal expansion is 12.8 µm/m·K (7.11 µin/in·°F).
Electrical3
Inconel 725 conducts electricity at 1.4 % IACS, worse than 51% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 81% of nickel alloy grades.
Sustainability4
Producing a kilogram of Inconel 725 takes about 250 MJ of energy and emits 18 kg of CO₂ — more than 97% of nickel alloy grades. Typical recycled content is 40%.
Manufacturability6
Inconel 725's machinability is not recommended (14/100, worse than 81% of nickel alloy grades); weldability good (55/100); formability poor (25/100).
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. Inconel 725 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Inconel 725
Is Inconel 725 easy to machine?
Treat like aged 718 but tougher: rigid setup, positive-rake coated carbide or ceramic at low speed/heavy feed, flood high-pressure coolant, constant engagement to avoid work-hardened glaze; rough in the solution-annealed state whenever possible.
Can Inconel 725 be welded?
GTAW/GMAW with matching 725 or ERNiCrMo-3 (625) filler, low heat input, no preheat, interpass <150 °C; re-solution anneal and double age after welding to restore strength and sour-service hardness compliance.
Can Inconel 725 be formed, bent or molded?
Cold form only in the solution-annealed condition (springback high, expect frequent intermediate anneals); hot work 1010–1180 °C with finishing above ~980 °C, then solution treat and age.
Inconel 725 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 |
|---|---|---|
| Ni | 55 – 59 | 57 |
| Cr | 19 – 22.5 | 21 |
| Mo | 7 – 9.5 | 8 |
| NbNb+Ta; γ″ former | 2.75 – 4 | 3.5 |
| Ti | 1 – 1.7 | 1.5 |
| Al | ≤ 0.35 | 0.2 |
| Mn | ≤ 0.35 | 0.1 |
| Si | ≤ 0.2 | 0.1 |
| Cu | ≤ 0.2 | 0.05 |
| C | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| P | ≤ 0.02 | 0.01 |
| Febalance, typically ~7–10 % | balance |
What surface finishes work on Inconel 725?
Not anodizable; passivates naturally so no coating is needed — pickle/blast to remove age-hardening oxide, then grind/polish or shot-peen threads and seal areas for fatigue and SCC resistance.
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 Inconel 725 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N07725
How much does Inconel 725 cost?
Inconel 725 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.
Inconel 725 — frequently asked
What is Inconel 725 used for?
Inconel 725 is typically used for oil and gas downhole tools, high-strength sour-service fasteners, subsea wellhead and hanger components, valve stems and trim for sour wells, packers and landing nipples and instrument and completion tubular parts. In short: age-hardened 625 chemistry; NACE sour-service strength; hard to machine when aged.
What is the yield strength of Inconel 725?
Inconel 725 has a typical yield strength of 890 MPa (129 ksi) and a tensile strength of 1,240 MPa (180 ksi) — stronger than 93% of nickel alloy grades. Strength varies by condition: see the 5 listed tempers.
Is Inconel 725 easy to machine?
Not especially — machinability is rated not recommended (14/100, worse than 81% of nickel alloy grades). Treat like aged 718 but tougher: rigid setup, positive-rake coated carbide or ceramic at low speed/heavy feed, flood high-pressure coolant, constant engagement to avoid work-hardened glaze; rough in the solution-annealed state whenever possible.
Can Inconel 725 be welded?
Yes — weldability is rated good (55/100). GTAW/GMAW with matching 725 or ERNiCrMo-3 (625) filler, low heat input, no preheat, interpass <150 °C; re-solution anneal and double age after welding to restore strength and sour-service hardness compliance.
What surface finishes work on Inconel 725?
Not anodizable; passivates naturally so no coating is needed — pickle/blast to remove age-hardening oxide, then grind/polish or shot-peen threads and seal areas for fatigue and SCC resistance.
Can Inconel 725 be formed, bent or molded?
Cold form only in the solution-annealed condition (springback high, expect frequent intermediate anneals); hot work 1010–1180 °C with finishing above ~980 °C, then solution treat and age.
What is the maximum service temperature of Inconel 725?
Inconel 725 is rated for continuous use to about 650°C (1,202 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Inconel 725 STA-120 and Inconel 725-SA?
STA-120 is the default condition — standard oilfield sour-service condition (API 6ACRA / NACE MR0175, ≤43 HRC) for downhole tools, hangers and valve parts. SA: soft supply condition for forming, machining of complex shapes or welding before final age hardening. Yield strength is 890 MPa in STA-120 versus 400 MPa in SA.
How much does Inconel 725 cost?
Inconel 725 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
- INCONEL alloy 725 datasheet — Special Metals Corporation (2004)
- API 6ACRA — Age-Hardened Nickel-Based Alloys for Oil and Gas Drilling and Production Equipment — API (2020)
- ANSI/NACE MR0175 / ISO 15156-3 — Cracking-resistant CRAs for H2S service — NACE/ISO (2020)
- ASTM B637 — Precipitation-Hardening Nickel Alloy Bars, Forgings and Forging Stock — ASTM (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
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.