Alloy 716 (625+) — Premium Precipitation Hardenable Nickel-Chromium-Molybdenum Superalloy
Product Description
FUSHUN METAL offers premium quality Alloy 716 (625+), a precipitation hardenable Nickel-Chromium-Molybdenum based superalloy that delivers an exceptional combination of high strength and superior corrosion resistance. This innovative material offers the high strength characteristics similar to Alloy 718 while providing the outstanding corrosion resistance comparable to Alloy 625. This unique combination makes Alloy 716 the ideal choice for demanding applications in oil and gas, chemical processing, and marine environments where both mechanical integrity and resistance to aggressive corrosive media are critical requirements.
The alloy’s exceptional properties are achieved through a carefully controlled chemical composition and optimized heat treatment process, resulting in a material that maintains its mechanical properties even in the harshest operating conditions. FUSHUN METAL supplies Alloy 716 in various product forms including round bars, flat bars, plates, and forgings, all manufactured to meet the most stringent industry specifications including ASTM B805, API 6A CRA, and NACE MR-0175/ISO 15156.
Standards and Specifications
Alloy 716 (625+) from FUSHUN METAL meets or exceeds the following industry standards and specifications:
| Standard | Designation |
|---|---|
| UNS | N07716 |
| ASTM | B805 |
| API | 6A CRA |
| NACE | MR-0175/ISO 15156 |
| Tradename | ALLOY 625+ |
Chemical Composition
FUSHUN METAL manufactures Alloy 716 (625+) with precise control of chemical composition according to the following requirements:
| Element | Content (%) |
|---|---|
| Nickel (Ni) | 59.0 – 63.0 |
| Chromium (Cr) | 19.0 – 22.0 |
| Molybdenum (Mo) | 7.00 – 9.50 |
| Niobium (Nb) + Tantalum (Ta) | 2.75 – 4.00 |
| Titanium (Ti) | 1.00 – 1.60 |
| Iron (Fe) | Balance |
| Aluminum (Al) | 0.35 Max |
| Carbon (C) | 0.03 Max |
| Silicon (Si) | 0.2 Max |
| Manganese (Mn) | 0.2 Max |
| Phosphorus (P) | 0.015 Max |
| Sulfur (S) | 0.01 Max |
| Boron (B) | 0.006 Max |
| Copper (Cu) | 0.23 Max |
| Lead (Pb) | 0.001 Max |
Role of Key Alloying Elements
- Nickel (59.0-63.0%): Forms the austenitic matrix and provides excellent resistance to corrosion, particularly in reducing environments. Also contributes to high-temperature stability and resistance to thermal cycling.
- Chromium (19.0-22.0%): Provides resistance to oxidation and corrosion, particularly in oxidizing environments, through the formation of a protective oxide layer.
- Molybdenum (7.00-9.50%): Significantly enhances resistance to pitting and crevice corrosion, especially in chloride-containing environments. Also contributes to solid solution strengthening.
- Niobium (2.75-4.00%): Together with titanium, forms primary strengthening precipitates during age hardening heat treatment, contributing to the alloy’s high strength.
- Titanium (1.00-1.60%): Forms strengthening precipitates and helps in age-hardening response. Also contributes to improved high-temperature properties.
Mechanical Properties
Alloy 716 (625+) from FUSHUN METAL exhibits exceptional mechanical properties in the solution annealed and aged condition:
| Property | Minimum Value | Typical Value |
|---|---|---|
| 0.2% Yield Strength | 120,000 PSI (827 MPa) | 125,000 PSI (862 MPa) |
| Tensile Strength | 150,000 PSI (1034 MPa) | 160,000 PSI (1103 MPa) |
| Elongation | 20% | 25% |
| Reduction of Area | 35% | 40% |
| Hardness (NACE Compliant) | 32 HRC | 32 – 43 HRC |
| Charpy V-Notch Impact @ -60°C | 37 Joules | 43 Joules |
Physical Properties
FUSHUN METAL’s Alloy 716 (625+) demonstrates the following typical physical properties:
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ (0.305 lb/in³) |
| Melting Range | 1290-1350°C (2354-2462°F) |
| Thermal Conductivity at 20°C | 10.8 W/m·K (6.2 BTU/hr/ft/°F) |
| Electrical Resistivity | 1.30 μΩ·m at 20°C |
| Coefficient of Thermal Expansion (20-100°C) | 13.1 × 10⁻⁶ /°C (7.3 × 10⁻⁶ /°F) |
| Specific Heat | 410 J/kg·K (0.098 BTU/lb/°F) |
| Young’s Modulus | 205 GPa (29.7 × 10⁶ psi) |
Key Advantages of Alloy 716 (625+)
Alloy 716 (625+) from FUSHUN METAL offers several significant advantages that make it a superior choice for demanding applications:
- Optimal Combination of Strength and Corrosion Resistance: Delivers the high strength similar to Alloy 718 with the exceptional corrosion resistance of Alloy 625, offering the best of both worlds in a single material.
- Superior Corrosion Resistance: Exceptional resistance to pitting, crevice corrosion, stress corrosion cracking, and general corrosion in both oxidizing and reducing environments.
- NACE MR-0175/ISO 15156 Compliance: Fully certified for use in sour gas environments, making it ideal for oil and gas applications where H₂S is present.
- High Mechanical Strength: The precipitation hardening capability provides excellent yield and tensile strength while maintaining good ductility.
- Excellent High-Temperature Properties: Maintains its mechanical properties at elevated temperatures, making it suitable for high-temperature service.
- Outstanding Fatigue Resistance: Superior resistance to cyclic loading, ensuring long service life in dynamic applications.
- Good Fabricability: Can be machined, formed, and welded using conventional techniques with proper procedures.
- Dimensional Stability: Minimal distortion during heat treatment and excellent dimensional stability during service.
Heat Treatment
FUSHUN METAL supplies Alloy 716 (625+) bar stock in the Solution Annealed and Aged condition as standard. Material may also be supplied in the Solution Annealed only condition upon request.
Standard Heat Treatment Process
- Solution Annealing: 1010-1065°C (1850-1950°F), hold for sufficient time based on section thickness, followed by rapid cooling (water quenching).
- Aging Treatment: Two-step aging process:
- First Step: 720-760°C (1330-1400°F) for 8 hours
- Furnace cool at 55°C (100°F) per hour to 620-660°C (1150-1220°F)
- Second Step: Hold at 620-660°C (1150-1220°F) for 8 hours
- Air cool to room temperature
This precise heat treatment schedule optimizes the precipitation hardening response to achieve the ideal combination of strength, ductility, and corrosion resistance in the final product.
Applications
Due to its exceptional combination of high strength and superior corrosion resistance, Alloy 716 (625+) from FUSHUN METAL is ideally suited for numerous demanding applications:
Oil and Gas Industry
- Downhole components for sour service environments
- Wellhead equipment and Christmas trees
- Subsurface safety valves
- Completion equipment
- Flow control devices
- Subsea equipment
- Pressure-containing components
Chemical Processing
- Process equipment for handling aggressive chemicals
- Heat exchangers
- Reaction vessels
- Valves and pumps
- Piping systems in corrosive environments
Marine Applications
- Propeller shafts
- Fasteners and hardware for seawater exposure
- Offshore platform components
- Marine exhaust systems
Aerospace and Defense
- High-strength components requiring corrosion resistance
- Structural elements in marine environments
- Exhaust system components
Power Generation
- Gas turbine components
- Fasteners for high-temperature service
- Heat recovery steam generator components
Available Product Forms
FUSHUN METAL provides Alloy 716 (625+) in various product forms to meet diverse manufacturing requirements:
Round Bars
| Diameter Range | Length | Surface Condition |
|---|---|---|
| 12mm – 300mm (0.5″ – 12″) | Random or cut-to-length | Black/As-forged, Rough-turned, Precision-ground, Polished |
Flat Bars
| Thickness | Width | Length |
|---|---|---|
| 10mm – 100mm (0.4″ – 4″) | 20mm – 200mm (0.8″ – 8″) | Random or cut-to-length |
Plates
| Thickness | Width | Length |
|---|---|---|
| 5mm – 50mm (0.2″ – 2″) | Up to 1500mm (60″) | Up to 6000mm (240″) |
Forgings
| Type | Weight Range | Condition |
|---|---|---|
| Open die forgings, rings, discs, blocks | Up to 2000kg | Solution annealed or solution annealed and aged |
Corrosion Resistance
Alloy 716 (625+) from FUSHUN METAL offers outstanding corrosion resistance in a wide range of aggressive environments, making it an excellent choice for applications where material integrity is critical:
General Corrosion Resistance
Similar to Alloy 625, Alloy 716 demonstrates exceptional resistance to general corrosion in both oxidizing and reducing environments, including:
- Mineral acids (sulfuric, phosphoric, nitric)
- Organic acids
- Alkaline solutions
- Seawater and marine environments
- Industrial atmospheres
Localized Corrosion Resistance
The high molybdenum content (7.00-9.50%) provides superior resistance to:
- Pitting corrosion in chloride-containing environments
- Crevice corrosion in stagnant conditions
- Stress corrosion cracking
Sour Service Performance
Alloy 716 is fully compliant with NACE MR-0175/ISO 15156 specifications, making it suitable for service in oil and gas environments containing hydrogen sulfide (H₂S). The alloy demonstrates excellent resistance to:
- Sulfide stress cracking (SSC)
- Hydrogen-induced cracking (HIC)
- Stress-oriented hydrogen-induced cracking (SOHIC)
High-Temperature Corrosion Resistance
The alloy also exhibits excellent resistance to various forms of high-temperature corrosion, including:
- Oxidation at elevated temperatures
- Carburization
- Sulfidation
- Hot corrosion (Type I and Type II)
Fabrication Guidelines
Alloy 716 (625+) can be fabricated using conventional techniques, with the following recommendations:
Machining
- Alloy 716 has machinability similar to other nickel-based superalloys
- Use rigid tooling setups to minimize chatter and deflection
- Carbide tooling with positive rake angles is recommended
- Lower cutting speeds compared to stainless steels are advised
- Adequate cooling and lubrication should be maintained
- Solution annealed condition is generally preferred for machining operations
Welding
- Gas Tungsten Arc Welding (GTAW/TIG) is the preferred method for joining
- Use matching filler metals (ERNiCrMo-3) or Alloy 625 filler metal
- Maintain clean surfaces free from contamination before welding
- Minimize heat input to prevent thermal distortion
- Pre-weld solution annealing may be beneficial for thick sections
- Post-weld heat treatment is recommended to restore corrosion resistance and mechanical properties
Forming
- Perform forming operations in the solution annealed condition
- Higher forces are required compared to austenitic stainless steels
- Minimum bend radius should be at least 2-3 times the material thickness
- Intermediate annealing may be necessary for severe forming operations
- Age hardening heat treatment should be performed after all forming operations are complete
Surface Finishing
- Standard grinding, polishing, and abrasive blasting techniques are effective
- Avoid contamination with iron particles during surface finishing
- Passivation treatments can enhance corrosion resistance
- Electro-polishing can provide superior surface finish and corrosion performance
Quality Assurance
FUSHUN METAL maintains the highest standards of quality for Alloy 716 (625+):
- Chemical Analysis: Each heat is analyzed using state-of-the-art spectrometers to ensure compositional compliance with specifications
- Mechanical Testing: Comprehensive testing including tensile, hardness, and impact properties
- Microstructural Examination: Proper grain size and precipitate distribution are verified through metallographic analysis
- Non-Destructive Testing: Ultrasonic, magnetic particle, and liquid penetrant inspection as required by specifications
- Corrosion Testing: Material is tested for resistance to specific corrosive environments when required
- Dimensional Inspection: All products undergo thorough dimensional verification
- Certification: Complete material test reports and certification documentation are provided with each shipment
- Traceability: Full traceability from melt to final product is maintained
Comparative Advantages
Understanding how Alloy 716 (625+) compares to similar alloys helps in selecting the optimal material for specific applications:
| Characteristic | Alloy 716 (625+) | Alloy 625 | Alloy 718 |
|---|---|---|---|
| Yield Strength | 120 ksi min | 60 ksi min | 150 ksi min |
| Corrosion Resistance | Excellent | Excellent | Good |
| Pitting Resistance | Superior | Superior | Moderate |
| NACE MR-0175 Compliance | Yes | Yes | Limited |
| Age Hardenability | Yes | No (standard grade) | Yes |
| Maximum Service Temperature | ~650°C (1200°F) | ~980°C (1800°F) | ~650°C (1200°F) |
| Optimal Application Area | Corrosive environments requiring high strength | Highly corrosive environments with moderate strength needs | High-strength applications with moderate corrosion concerns |
Why Choose FUSHUN METAL for Alloy 716 (625+)
Selecting FUSHUN METAL as your supplier for Alloy 716 (625+) provides numerous advantages:
- Material Expertise: Our team of metallurgists and engineers has extensive experience with nickel-based superalloys and their applications
- Manufacturing Excellence: State-of-the-art production facilities with stringent quality control measures ensure consistent material properties
- Comprehensive Testing: All products undergo thorough testing to verify mechanical properties, dimensional accuracy, and corrosion resistance
- Custom Solutions: Ability to tailor product specifications to meet specific application requirements
- Technical Support: Expert assistance with material selection, heat treatment, and fabrication guidelines
- Global Supply Capability: Worldwide distribution network ensures timely delivery
- Industry Compliance: All products meet or exceed relevant industry standards including ASTM, API, and NACE specifications
- Competitive Pricing: Excellent value proposition for premium superalloy products
Request Information
Contact FUSHUN METAL today to discuss your Alloy 716 (625+) requirements. Our technical team is ready to assist you with:
- Detailed technical specifications
- Custom size and property requirements
- Fabrication recommendations
- Application-specific material selection guidance
- Price quotations and delivery schedules
- Material certification and testing requirements
