Hangbo Alloy Group
Shanghai · Est. 2012
UNS N07725 / W.Nr. 2.7725 — Chemical composition, mechanical properties, temperature limits, and corrosion resistance data for engineers and procurement professionals.
Inconel 725 (UNS N07725 / W.Nr. 2.7725) is a nickel-chromium-molybdenum-niobium alloy that is closely related to Inconel 625 but with higher titanium content added to enable precipitation hardening. This composition delivers the outstanding corrosion resistance of the Inconel 625 family while providing significantly higher strength through age-hardening heat treatment. The alloy retains excellent resistance to chloride pitting, crevice corrosion, and stress corrosion cracking, and it resists a wide range of reducing and oxidizing acids. Inconel 725 is particularly valued in the oil and gas industry for downhole and wellhead components, hangers, and fasteners exposed to sour gas, high chloride brines, and elevated temperatures. It is also used in marine and chemical processing applications requiring both high strength and long-term corrosion resistance.
The chemical composition of Inconel 725 is carefully balanced to achieve its unique combination of high-temperature strength, corrosion resistance, and fabricability. Tight control of trace elements ensures consistent mechanical properties and weldability.
| Element | Min % | Max % |
|---|---|---|
| Nickel (Ni) | 55.0 | 59.0 |
| Chromium (Cr) | 19.0 | 22.5 |
| Molybdenum (Mo) | 7.0 | 9.5 |
| Niobium + Tantalum (Nb+Ta) | 2.75 | 4.0 |
| Titanium (Ti) | 1.0 | 1.7 |
| Iron (Fe) | Balance | Balance |
| Aluminum (Al) | — | 0.35 |
| Carbon (C) | — | 0.03 |
| Silicon (Si) | — | 0.50 |
| Manganese (Mn) | — | 0.35 |
| Phosphorus (P) | — | 0.015 |
| Sulfur (S) | — | 0.015 |
Inconel 725 exhibits a face-centered cubic (FCC) austenitic matrix, which provides excellent ductility and toughness from cryogenic temperatures up to its maximum service limit. The physical properties below are typical values at room temperature.
| Property | Value | Unit |
|---|---|---|
| Density | 8.31 | g/cm³ |
| Melting Point | 1260 | °C |
| Specific Heat (21°C) | 440 | J/kg·K |
| Thermal Conductivity (21°C) | 9.6 | W/m·K |
| Electrical Resistivity (21°C) | 1.26 | μΩ·m |
| Modulus of Elasticity (21°C) | 204 | GPa |
| Mean CTE (21-93°C) | 12.6 | μm/m·°C |
The mechanical properties of Inconel 725 vary depending on product form, cold work, and heat treatment condition. The data below represents typical values for solution-annealed and aged material according to applicable ASTM and AMS specifications.
| Property | Value |
|---|---|
| Tensile Strength (solution annealed) | 855 MPa (124 ksi) |
| Yield Strength (solution annealed) | 517 MPa (75 ksi) |
| Tensile Strength (aged) | 1200-1300 MPa (174-189 ksi) |
| Yield Strength (aged) | 1100-1200 MPa (160-174 ksi) |
| Elongation in 2 inches (aged) | 20-25% |
| Hardness (aged) | 38-45 HRC |
| Impact Strength (Charpy V) | Good |
| Fatigue Strength | Excellent at high cycles |
Inconel 725 maintains useful strength at elevated temperatures, with performance dependent on the strengthening mechanisms active in the alloy. The following table summarizes typical tensile strength, yield strength, and elongation values across a range of elevated temperatures.
| Temperature (°C) | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 21 (Room) | 1200 | 1150 | 23 |
| 316 | 1100 | 1050 | 24 |
| 427 | 1020 | 970 | 25 |
| 538 | 900 | 850 | 26 |
| 650 | 760 | 720 | 28 |
| 760 | 520 | 480 | 32 |
Inconel 725 offers outstanding corrosion resistance that rivals Inconel 625 and Inconel 718 in many environments. In seawater, the alloy strongly resists pitting and crevice corrosion, with critical pitting temperatures well above ambient. It is highly resistant to chloride-induced stress corrosion cracking, making it an excellent choice for subsea equipment, marine fasteners, and heat exchangers. In sour service containing hydrogen sulfide, carbon dioxide, and chlorides, Inconel 725 maintains its integrity and is listed in NACE MR0175 / ISO 15156 for such environments. The alloy also resists nitric, phosphoric, and sulfuric acids, and performs well in oxidizing and mildly reducing chemical process streams. The niobium content stabilizes the alloy against sensitization, ensuring good corrosion resistance in the heat-affected zone after welding.
The unique combination of high strength, corrosion resistance, and fabricability makes Inconel 725 suitable for a wide range of demanding industrial applications:
Hangbo Alloy Group manufactures and supplies Inconel 725 in the following product forms, conforming to ASTM, AMS, and industry specifications:
| Standard | Description |
|---|---|
| ASTM B805 | Precipitation-Hardening Nickel Alloy Bar and Rod |
| AMS 5668 | Bars, Forgings, and Rings |
| AMS 5964 | Wire |
| ASTM B637 | Precipitation-Hardening and Cold-Worked Nickel Alloy Bars, Forgings, and Forging Stock |
| NACE MR0175/ISO 15156 | Sulfide Stress Cracking Resistant Materials |
| API 6A | Wellhead and Christmas Tree Equipment |
Inconel 725 has a density of approximately 8.31 g/cm³, comparable to other nickel-chromium-molybdenum alloys such as Inconel 625.
The melting point of Inconel 725 is approximately 1260 °C (2300 °F), which is lower than many cobalt-based superalloys.
Inconel 725 contains 55-59% nickel, 19-22.5% chromium, 7-9.5% molybdenum, 2.75-4% niobium plus tantalum, 1-1.7% titanium, with iron making up the balance and tight limits on carbon, silicon, and manganese.
Inconel 725 is commonly supplied to ASTM B805, AMS 5668, AMS 5964, NACE MR0175/ISO 15156, and API 6A for oilfield and high-strength applications.
Inconel 725 is typically solution annealed at 980-1040 °C, followed by aging at approximately 730 °C for 8 hours plus furnace cooling to 620 °C for 8 hours to precipitate γ'' strengthening phases.
Inconel 725 is available as round bar, wire, custom fasteners, forgings, and limited sheet and plate. Bar and wire are the most common product forms.
Inconel 725 is a premium precipitation-hardening alloy. Pricing depends on form, size, quantity, certification, and heat treatment. Request a quotation for accurate pricing.
Yes, Inconel 725 is weldable using GTAW, GMAW, and SMAW processes. Matching filler metals such as ERNiCrMo-15 are recommended, and post-weld heat treatment is typically required to restore strength and corrosion resistance.
Inconel 725 has similar corrosion resistance to Inconel 625 but offers significantly higher strength through precipitation hardening. It is preferred for applications requiring high strength plus sour-service corrosion resistance.
Standard bar and wire sizes are typically available in 2-4 weeks. Minimum order quantities generally start at 100 kg for bar and 50 kg for wire, depending on size.
Inconel 725 is suitable for continuous service up to about 650 °C (1200 °F) and short-term exposure to higher temperatures, though its strength decreases above this range.
Common applications include downhole oil and gas components, wellhead fasteners, subsea connectors, marine hardware, chemical processing equipment, and FGD system components.
Yes, Inconel 725 is NACE MR0175/ISO 15156 compliant and widely used in H₂S, CO₂, and chloride-containing sour gas environments.
Yes, Inconel 725 exhibits excellent resistance to pitting, crevice corrosion, and stress corrosion cracking in seawater.
Aged Inconel 725 typically reaches 38-45 HRC, with tensile strength exceeding 1200 MPa depending on the degree of cold work and aging parameters.
Hangbo Alloy Group maintains extensive inventory of Inconel 725 in all standard product forms. We can provide mill test certificates, third-party inspection reports (SGS, TUV), and custom processing services including cutting, machining, and surface finishing.
For quotations, material certifications, or technical consultation, contact our sales team or call +86-136-1165-6360. We typically respond within 10 minutes.
Request a quotation for Inconel 725 round bars, tubes, plates, or forgings. We stock standard sizes and accept custom orders.