Alloy 725,Inconel 725,UNS N07725,EFORU

### **Technical Datasheet: Alloy 725 (Inconel 725, UNS N07725)** 

 **Introduction** Alloy 725 is a precipitation-hardenable nickel-chromium-molybdenum-niobium alloy designed to provide exceptional strength and outstanding corrosion resistance in severe environments. It was developed to offer a combination of very high strength, comparable to Alloy 718, with a corrosion resistance that is significantly superior, approaching that of alloys like C-276 in many environments. Its excellent resistance to sulfide stress cracking, pitting, and crevice corrosion makes it a premium material for demanding applications in the oil & gas, marine, and chemical processing industries. 

### **Technical Datasheet: Alloy 725 (Inconel 725, UNS N07725)** 

 **Introduction** Alloy 725 is a precipitation-hardenable nickel-chromium-molybdenum-niobium alloy designed to provide exceptional strength and outstanding corrosion resistance in severe environments. It was developed to offer a combination of very high strength, comparable to Alloy 718, with a corrosion resistance that is significantly superior, approaching that of alloys like C-276 in many environments. Its excellent resistance to sulfide stress cracking, pitting, and crevice corrosion makes it a premium material for demanding applications in the oil & gas, marine, and chemical processing industries. 

 **Key Features** *   

**Exceptional Corrosion Resistance:

** Excellent resistance to pitting, crevice corrosion, and sulfide stress cracking (SSC), especially in sour (H₂S-containing) oil and gas environments. *   

**High Strength:** Can be heat treated to very high strength levels, surpassing many other corrosion-resistant alloys. *   

**Versatile Fabricability:** Can be welded and fabricated using common techniques, with the weldment responding to age-hardening. *   *

*Good Resistance to Chloride-Induced Stress Corrosion Cracking (Cl-SCC).** 

1. Chemical Composition (Weight %)

** The typical composition of Alloy 725 is specified in various international standards. The following is a representative range: 

| Element | Minimum (%) | Maximum (%) | 

| :--- | :--- | :--- | 

| **Nickel (Ni)** | 55.0 | 59.0 | 

| **Chromium (Cr)** | 19.0 | 22.5 | 

| **Molybdenum (Mo)** | 7.0 | 9.5 | 

| **Iron (Fe)** | 2.0 | 8.0 | 

| **Niobium (Nb) + Tantalum (Ta)** | 2.75 | 4.00 | 

| **Titanium (Ti)** | 1.00 | 1.70 | 

| **Aluminum (Al)** | 0.35 | 0.75 | 

| **Carbon (C)** | - | 0.03 | 

| **Manganese (Mn)** | - | 0.35 | 

| **Silicon (Si)** | - | 0.20 | 

| **Phosphorus (P)** | - | 0.015 | 

| **Sulfur (S)** | - | 0.010 | 

 *The alloy is strengthened by the precipitation of gamma prime [Ni₃(Al,Ti)] and gamma double prime [Ni₃Nb] phases during the aging heat treatment, similar to Alloy 718, but with a chemistry optimized for corrosion resistance.* 

2. Physical Properties** 

 | Property | Value | 

| :--- | :--- | 

| **Density** | 8.31 g/cm³ (0.300 lb/in³) | 

| **Melting Range** | ~ 1320 - 1360 °C (~ 2410 - 2480 °F) | 

| **Specific Heat (20°C)** | ~ 440 J/kg·K | 

| **Thermal Conductivity (20°C)** | ~ 10.8 W/m·K | 

| **Mean Coefficient of Thermal Expansion (20-100°C)** | ~ 12.9 µm/m·°C | 

| **Modulus of Elasticity (Young's Modulus)** | ~ 204 GPa (29.5 x 10⁶ psi) | 

3. Mechanical Properties

 (Typical for Annealed & Aged Condition - ASTM B805)** Properties are achieved through a solution anneal followed by a two-step aging process. 

 **Room Temperature (Bar & Forging Stock):** *   

**Tensile Strength:** ≥ 1100 MPa (160 ksi) *   

**Yield Strength (0.2% Offset):** ≥ 760 MPa (110 ksi) *   

**Elongation:** ≥ 15% **Room Temperature (High-Strength Condition - e.g., Fasteners):** *   

**Tensile Strength:** ≥ 1275 MPa (185 ksi) *   

**Yield Strength (0.2% Offset):** ≥ 1035 MPa (150 ksi) *   

**Elongation:** ≥ 12% 

4. International Standards** 

 Alloy 725 is covered by several key ASTM and NACE standards, reflecting its primary use in corrosive oil and gas applications. 

 | Product Form | Standard Examples | 

| :--- | :--- | 

| **Bar, Wire, Forgings** | **ASTM B805** (Age-Hardened Bar & Wire), **UNS N07725** | 

| **Plate, Sheet, Strip** | **ASTM B829** (General Requirements for Ni Alloy Pipe/Tube/Plate) | 

| **Tubing & Casing** | **ASTM B517**, **ASTM B705** (Welded Pipe) | 

| **Fittings & Flanges** | **ASTM B366** | 

| **Corrosion Performance** | **NACE MR0175/ISO 15156** (Suitable for use in sour service) | 

5. Product Applications** 

 Alloy 725 is predominantly used in the most aggressive downhole and subsea environments where high strength and superior corrosion resistance are mandatory. *   

**Oil & Gas Industry:**    *   

**Downhole Tubulars & Casing**    *   

**Wellhead Components** (hangers, packers, mandrels)    *   

**Subsea Christmas Tree Components** (valves, stems, hubs)    *   

**Downhole Tooling** and **Fasteners** for sour service    *   

**Flowlines** and **Risers** in deep-sea applications *   

**Marine & Chemical Processing:**    *   

**Fasteners** and **bolts** in marine environments    *   

**Pump Shafts** and **Valve Components** handling corrosive chemicals    *   

**Process Vessels** and **Heat Exchangers** in chloride-containing media --- 

 **Conclusion** 

Alloy 725 (Inconel 725, UNS N07725) is a premium, high-strength, corrosion-resistant nickel alloy that bridges the gap between the high strength of Alloy 718 and the exceptional corrosion resistance of the Ni-Cr-Mo "C-family" alloys. Its ability to be thermally processed to very high strength levels while maintaining outstanding resistance to sulfide stress cracking and pitting makes it an indispensable engineering material for critical components in the oil & gas and other industries operating in the world's most challenging environments.

Packing of Alloy 725 (Inconel 725, UNS N07725) 

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 1638 gallon liquid totes Special package is available on request.