INCONEL® Alloy 725: Comprehensive Product Introduction
INCONEL® alloy 725 is a nickel-chromium-molybdenum-niobium alloy renowned for its exceptional corrosion resistance and high strength, particularly in sour gas environments containing hydrogen sulfide and chlorides. Developed for applications requiring excellent resistance to stress corrosion cracking (SCC) and pitting, INCONEL® 725 finds extensive use in oil and gas production, chemical processing, and marine environments. This article provides a detailed introduction to INCONEL® alloy 725, covering its chemical composition, mechanical properties, performance at different temperatures, corresponding grades, industry applications, available forms, sizes, production standards, and essential information on welding, machining, polishing, heat treatment, and cold processing across major global markets.
Chemical Composition of INCONEL® Alloy 725
INCONEL® alloy 725 is composed of specific elements to achieve its superior properties:
| Element | Composition (%) |
|---|---|
| Nickel (Ni) | 58.0 min |
| Chromium (Cr) | 19.0-22.5 |
| Molybdenum (Mo) | 7.0-9.5 |
| Niobium (Nb) | 2.75-4.0 |
| Titanium (Ti) | 1.0-1.7 |
| Aluminum (Al) | 0.35 max |
| Iron (Fe) | 5.0 max |
| Tantalum (Ta) | 0.35 max |
| Manganese (Mn) | 0.50 max |
| Silicon (Si) | 0.35 max |
| Carbon (C) | 0.03 max |
| Sulfur (S) | 0.010 max |
| Phosphorus (P) | 0.015 max |
Mechanical Properties of INCONEL® Alloy 725
INCONEL® alloy 725 exhibits robust mechanical properties suitable for demanding applications:
| Property | Value |
|---|---|
| Tensile Strength | 1034 MPa (150 ksi) min |
| Yield Strength (0.2% offset) | 758 MPa (110 ksi) min |
| Elongation | 15% min |
| Hardness (Rockwell C) | 34-42 |
| Density | 8.31 g/cm³ |
Performance at Different Temperatures
INCONEL® alloy 725 maintains its mechanical properties across a range of temperatures:
| Temperature Range | Performance |
|---|---|
| Room Temperature | High strength and corrosion resistance |
| Elevated Temperatures (up to 650°C / 1200°F) | Retains strength and oxidation resistance |
| Cryogenic Temperatures | Maintains toughness and ductility |
Corresponding Grades in Different Countries
INCONEL® alloy 725 is identified by various grades in different countries and regions:
| Country/Region | Grade |
|---|---|
| USA | UNS N07725 |
| Germany | 2.4668 |
| France | NC22DNB |
| UK | – |
| Japan | – |
| China | GH4169 |
Standard Forms, Sizes, and Production Standards
Forms and Sizes
INCONEL® alloy 725 is available in various forms and sizes to meet industrial requirements:
| Form | Size Range |
|---|---|
| Sheets | Thickness: 0.5 mm – 50 mm |
| Plates | Thickness: 1 mm – 100 mm |
| Bars | Diameter: 6 mm – 300 mm |
| Wire | Diameter: 0.1 mm – 10 mm |
| Tubes | Outer Diameter: 3 mm – 200 mm |
| Pipes | Outer Diameter: 6 mm – 300 mm |
| Forgings | Various shapes and sizes as per standards |
Production Standards
INCONEL® alloy 725 conforms to international production standards:
| Standard | Description |
|---|---|
| ASTM B805 | Bars and wire |
| AMS 5832 | Bars and forgings |
| NACE MR0175/ISO 15156 | Sour gas service |
| API 6A718 | Oil and gas applications |
Welding, Machining, Polishing, Heat Treatment, and Cold Processing
INCONEL® alloy 725 exhibits good weldability, machinability, and formability, making it suitable for various fabrication processes in the following ways:
- Welding: GTAW (Gas Tungsten Arc Welding) and GMAW (Gas Metal Arc Welding) are commonly used methods, with precautions for preheating and post-weld heat treatment.
- Machining: Carbide tools and coolant are recommended for achieving precise dimensions and surface finishes.
- Polishing: Mechanical and chemical methods are employed to enhance surface smoothness and corrosion resistance.
- Heat Treatment: Solution annealing followed by age hardening enhances mechanical properties and resistance to environmental factors.
- Cold Processing: Forming and bending processes maintain material integrity and strength, suitable for various component geometries.
Industry Applications of INCONEL® Alloy 725
INCONEL® alloy 725 is indispensable in critical applications across various industries:
- Oil and Gas: Downhole components, wellhead equipment, and tubing systems for sour gas environments.
- Chemical Processing: Valve components, reactor vessels, and piping systems exposed to corrosive fluids.
- Marine: Propeller shafts, seawater cooling systems, and underwater equipment requiring high corrosion resistance.
- Aerospace: Turbine blades, combustion chambers, and structural components in jet engines.
Conclusion
INCONEL® alloy 725 stands out as a versatile and durable material offering superior corrosion resistance, high strength, and reliability in demanding industrial environments. Its well-defined chemical composition, robust mechanical properties, adherence to international standards, and suitability for various fabrication processes make it a preferred choice for critical applications worldwide. Engineers and designers seeking longevity and performance in challenging environments can confidently select INCONEL® alloy 725 for their projects.
For detailed technical specifications and customized solutions, consulting with material suppliers and referencing specific product data sheets is recommended.
This comprehensive introduction and detailed data sheet provide a thorough overview of INCONEL® alloy 725, emphasizing its chemical composition, mechanical properties, performance characteristics at different temperatures, applications, and advantages in demanding industrial environments across various countries.