Alloy 725，Inconel 725 ，UNS N07725，EFORU

British Specs:，American Specs:ASTM B805，German Specs:

### **Product Introduction: Alloy 725 / Inconel 725 (UNS N07725)** #### **Overview** **Alloy 725** (commercially known as **Inconel® 725**) is a precipitation-hardenable nickel-chromium-molybdenum-niobium alloy specifically designed to provide exceptional corrosion resistance combined with high strength. This advanced superalloy offers outstanding performance in severe corrosive environments, including sour gas (H₂S-containing) wells, and maintains excellent mechanical properties at temperatures up to 650°C (1200°F). The alloy's superior resistance to pitting, crevice corrosion, and stress corrosion cracking makes it particularly suitable for critical components in oil and gas, chemical processing, and marine applications. The alloy derives its enhanced properties through a unique precipitation-hardening mechanism involving the formation of gamma prime [γ'] and gamma double prime [γ''] phases, providing an optimal combination of strength and corrosion resistance. --- #### **Chemical Composition** The chemical composition of Alloy 725 (UNS N07725) is carefully balanced for optimal performance: | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | 55.0 - 59.0 | | **Chromium (Cr)** | 19.0 - 22.5 | | **Molybdenum (Mo)** | 7.0 - 9.5 | | **Iron (Fe)** | 5.0 - 9.0 | | **Niobium (Nb)** | 2.75 - 4.00 | | **Titanium (Ti)** | 1.0 - 1.7 | | **Aluminum (Al)** | 0.35 - 0.75 | | **Manganese (Mn)** | ≤ 0.35 | | **Silicon (Si)** | ≤ 0.20 | | **Carbon (C)** | ≤ 0.03 | | **Sulfur (S)** | ≤ 0.010 | | **Copper (Cu)** | ≤ 0.20 | | **Phosphorus (P)** | ≤ 0.015 | *The optimized composition provides excellent corrosion resistance while enabling effective precipitation hardening through gamma double prime [γ'' Ni₃Nb] phase formation.* --- #### **Physical Properties** Critical properties for design and engineering applications: | Property | Metric Value | Imperial Value | | :--- | :--- | :--- | | **Density** | 8.31 g/cm³ | 0.300 lb/in³ | | **Melting Range** | 1320 - 1360 °C | 2410 - 2480 °F | | **Specific Heat (20°C)** | 442 J/kg·K | 0.106 Btu/lb·°F | | **Thermal Conductivity (20°C)** | 10.8 W/m·K | 75.0 Btu·in/hr·ft²·°F | | **Thermal Expansion Coefficient (20-100°C)** | 12.9 μm/m·°C | 7.2 μin/in·°F | | **Modulus of Elasticity** | 206 GPa | 29.9 x 10⁶ psi | | **Electrical Resistivity** | 1.28 μΩ·m | - | --- #### **Mechanical Properties** Enhanced mechanical properties achieved through optimized heat treatment: **Solution Annealed + Aged Condition:** * **Ultimate Tensile Strength:** 1100-1240 MPa (160-180 ksi) * **Yield Strength (0.2% Offset):** 760-895 MPa (110-130 ksi) * **Elongation:** 15-25% * **Reduction of Area:** 35-50% * **Hardness:** 30-40 HRC **Elevated Temperature Performance:** * **0.2% Yield Strength at 205°C (400°F):** ≥ 690 MPa (100 ksi) * **Stress Rupture Life at 650°C (1200°F):** ≥ 100 hours at 310 MPa (45 ksi) * **Creep Resistance:** Excellent up to 650°C (1200°F) --- #### **International Standards** Alloy 725 conforms to several international specifications: **ASTM Standards:** * **ASTM B805:** Precipitation Hardening Nickel Alloy Bars, Forgings, and Forging Stock * **ASTM B649:** Nickel-Iron-Chromium-Molybdenum-Columbium Stabilized Alloy Rod and Bar * **ASTM B670:** Precipitation Hardening Nickel Alloy Plate, Sheet, and Strip **NACE Standards:** * **NACE MR0175/ISO 15156:** Suitable for use in H₂S-containing environments * **NACE MR0103:** Resistance to sulfide stress cracking **Other International Standards:** * **ISO 9724:** Nickel and Nickel Alloy Forgings * **DIN 17752:** Wrought Nickel and Nickel Alloys * **GB/T 15007:** Chinese Standard for Corrosion Resistant Alloys --- #### **Product Applications** Alloy 725 serves in the most demanding corrosive applications across multiple industries: **Oil & Gas Industry:** * **Downhole Tools:** Drill collars, subs, hangers, and mandrels for sour service * **Wellhead Equipment:** Valve components, Christmas tree parts, wellhead seals * **Subsea Systems:** Connectors, pressure-containing components, flowline parts * **Surface Equipment:** Pump shafts, valve stems, fasteners for corrosive service **Chemical Processing:** * **Reactor Vessels:** High-pressure reactors for corrosive chemical processes * **Heat Exchangers:** Tube sheets, tubes, and header components * **Pump Components:** Shafts, impellers, and casing parts * **Valve Components:** Trim parts, stems, and bodies for corrosive service **Marine & Offshore:** * **Marine Components:** Propeller shafts, seawater piping systems * **Offshore Structures:** Tensioner systems, mooring components * **Desalination Plants:** Heat exchanger tubes, brine heater components **Power Generation:** * **Nuclear Components:** Core internals, fastening systems * **FGD Systems:** Scrubber components, ducting systems * **Heat Exchangers:** Condenser tubes, feedwater heater components --- #### **Key Advantages** * **Exceptional Corrosion Resistance:** Superior performance in sour gas and chloride-containing environments * **High Strength:** Excellent mechanical properties maintained in corrosive conditions * **Outstanding Stress Corrosion Cracking Resistance:** Superior resistance to SCC in chloride environments * **Excellent Pitting Resistance:** High resistance to pitting and crevice corrosion * **Good Fabricability:** Can be welded, forged, and machined using standard methods * **Superior Fatigue Performance:** Excellent resistance to corrosion fatigue * **Weldability:** Good weldability with proper procedures and post-weld heat treatment * **Long Service Life:** Maintains performance in aggressive environments over extended periods **Heat Treatment Specifications:** * **Solution Treatment:** 980-1010°C (1800-1850°F) followed by rapid cooling * **Aging Treatment:** 620-650°C (1150-1200°F) for 8-12 hours, air cool * **Double Aging:** Optional second aging at 590-620°C (1100-1150°F) for enhanced properties **Corrosion Performance:** * **Critical Pitting Temperature (ASTM G48):** > 85°C (185°F) * **Critical Crevice Temperature (ASTM G48):** > 65°C (150°F) * **Sulfide Stress Cracking:** Resistant per NACE MR0175 **Note:** *Inconel® is a registered trademark of Special Metals Corporation. Alloy 725 requires specific heat treatment cycles to achieve optimal combination of strength and corrosion resistance. The alloy demonstrates good weldability but requires proper post-weld heat treatment to restore corrosion resistance in the heat-affected zone. Comprehensive material certification including chemical analysis, mechanical properties, and corrosion testing reports are typically provided for critical applications.*

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1806 gallon liquid totes Special package is available on request.