Overview
Inconel 625 is a high-performance nickel-chromium-molybdenum-niobium superalloy renowned for its exceptional corrosion resistance, high strength, fatigue resistance, oxidation resistance, and weldability.
Unlike many nickel alloys that require precipitation hardening, Inconel 625 derives its strength primarily from solid-solution strengthening provided by molybdenum and niobium additions. This results in outstanding mechanical properties across a wide temperature range while maintaining excellent corrosion resistance.
Inconel 625 is widely used in:
- Aerospace Components
- Marine Engineering
- Offshore Oil & Gas Equipment
- Chemical Processing Systems
- Power Generation Equipment
- Nuclear Applications
- Heat Exchangers
- Exhaust Systems
Due to its superior resistance to aggressive environments and high temperatures, Inconel 625 is one of the most versatile nickel-based superalloys available today.
Material Specification
| Property | Value |
|---|---|
| Material Designation | Inconel 625 |
| UNS Number | N06625 |
| Werkstoff Number | 2.4856 |
| ASTM Standards | ASTM B443, B444, B446, B564 |
| Material Family | Nickel-Chromium-Molybdenum Superalloy |
| Density | 8.44 g/cm³ |
| Magnetic Property | Non-Magnetic |
| Typical Supply Condition | Annealed |
| Standard Forms | Sheet, Plate, Bar, Rod, Pipe, Tube, Wire, Forgings |
Chemical Composition
| Element | Content (%) |
|---|---|
| Nickel (Ni) | ≥58.0 |
| Chromium (Cr) | 20.0–23.0 |
| Molybdenum (Mo) | 8.0–10.0 |
| Niobium + Tantalum (Nb+Ta) | 3.15–4.15 |
| Iron (Fe) | ≤5.0 |
| Carbon (C) | ≤0.10 |
| Manganese (Mn) | ≤0.50 |
| Silicon (Si) | ≤0.50 |
| Phosphorus (P) | ≤0.015 |
| Sulfur (S) | ≤0.015 |
The high molybdenum and niobium content provides exceptional strength and resistance to pitting and crevice corrosion.
Mechanical Properties
Annealed Condition
| Property | Value |
|---|---|
| Tensile Strength | ≥827 MPa |
| Yield Strength (0.2%) | ≥414 MPa |
| Elongation | ≥30% |
| Hardness | 180–240 HB |
| Elastic Modulus | 205 GPa |
Typical Mechanical Performance
| Property | Value |
|---|---|
| Fatigue Resistance | Outstanding |
| Impact Toughness | Excellent |
| Creep Resistance | Excellent |
| Ductility | Excellent |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ |
| Melting Range | 1290–1350°C |
| Thermal Conductivity | 9.8 W/m·K |
| Electrical Conductivity | 1.2% IACS |
| Electrical Resistivity | 1.29 μΩ·m |
| Thermal Expansion Coefficient | 12.8 × 10⁻⁶/K |
| Specific Heat Capacity | 435 J/kg·K |
High Temperature Performance
| Property | Performance |
|---|---|
| Oxidation Resistance | Excellent |
| Creep Resistance | Excellent |
| Thermal Stability | Excellent |
| Service Temperature | Up to 980°C |
Inconel 625 maintains excellent mechanical properties in both cryogenic and elevated-temperature environments.
Strength-to-Weight Ratio
| Material | Density (g/cm³) | Tensile Strength |
|---|---|---|
| Inconel 625 | 8.44 | 827 MPa |
| Inconel 600 | 8.47 | 550 MPa |
| Inconel 718 | 8.19 | 1240 MPa |
| 316L Stainless Steel | 8.00 | 485 MPa |
Inconel 625 offers significantly higher strength than Inconel 600 while maintaining outstanding corrosion resistance.
Corrosion Resistance
| Environment | Performance |
|---|---|
| Seawater | Outstanding |
| Chloride Solutions | Outstanding |
| Acidic Environments | Excellent |
| Alkaline Solutions | Excellent |
| Oxidizing Environments | Excellent |
| Reducing Environments | Excellent |
Inconel 625 is highly resistant to:
- Pitting Corrosion
- Crevice Corrosion
- Stress Corrosion Cracking
- Intergranular Corrosion
- Chloride Attack
Recommended surface treatments:
- Pickling
- Passivation
- Electropolishing
- Mechanical Polishing
Marine Corrosion Resistance
| Property | Rating |
|---|---|
| Seawater Resistance | Outstanding |
| Salt Spray Resistance | Outstanding |
| Biofouling Resistance | Excellent |
| Offshore Durability | Outstanding |
Inconel 625 is one of the most widely used nickel alloys for offshore and subsea applications.
Weldability
| Welding Process | Rating |
|---|---|
| TIG Welding | Outstanding |
| MIG Welding | Outstanding |
| Resistance Welding | Excellent |
| Laser Welding | Excellent |
Inconel 625 can be welded without post-weld heat treatment in most applications.
Machinability
| Process | Rating |
|---|---|
| CNC Turning | Moderate |
| CNC Milling | Moderate |
| Drilling | Moderate |
| Grinding | Good |
| EDM Machining | Excellent |
Machinability Comparison
| Material | Machinability |
|---|---|
| Aluminum 6061 | Excellent |
| 316 Stainless Steel | Good |
| Inconel 625 | Moderate |
| Inconel 718 | Difficult |
Work hardening requires rigid setups and optimized cutting parameters.
Heat Treatment
Solution Annealing
| Parameter | Value |
|---|---|
| Temperature | 1093–1204°C |
| Cooling Method | Rapid Air Cool or Water Quench |
Stress Relief
| Parameter | Value |
|---|---|
| Temperature | 870–980°C |
| Cooling Method | Air Cool |
Heat Treatability
| Property | Performance |
|---|---|
| Solution Annealing | Excellent |
| Precipitation Hardening | No |
| Structural Stability | Outstanding |
Inconel 625 gains strength primarily through solid-solution strengthening rather than aging treatments.
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| UNS | N06625 |
| ASTM | Inconel 625 |
| DIN | 2.4856 |
| EN | NiCr22Mo9Nb |
| ISO | NiCr22Mo9Nb |
| JIS | NCF625 |
| GB/T (China) | NS336 |
Available Forms
| Product Type | Availability |
|---|---|
| Plate | Yes |
| Sheet | Yes |
| Round Bar | Yes |
| Pipe | Yes |
| Tube | Yes |
| Wire | Yes |
| Forgings | Yes |
Typical Applications
Aerospace Industry
- Exhaust Systems
- Engine Components
- Thrust Reversers
- Turbine Components
Oil & Gas Industry
- Subsea Equipment
- Flexible Risers
- Wellhead Components
- Offshore Piping Systems
Marine Industry
- Propeller Components
- Seawater Systems
- Offshore Structures
- Marine Fasteners
Chemical Processing
- Heat Exchangers
- Reactors
- Process Piping
- Acid Handling Systems
Power Generation
- Flue Gas Desulfurization Systems
- Turbine Components
- High-Temperature Equipment
Nuclear Industry
- Reactor Components
- Cooling Systems
- Containment Equipment
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| CNC Machining | Good |
| Welding | Outstanding |
| Forming | Good |
| Deep Drawing | Good |
| Forging | Excellent |
Advantages
Exceptional Corrosion Resistance
Outstanding performance in seawater, acids, and chloride-rich environments.
High Strength
Much stronger than Inconel 600 and most stainless steels.
Excellent Weldability
Can be welded without significant loss of corrosion resistance.
Outstanding Fatigue Resistance
Suitable for cyclic loading and offshore applications.
Excellent High-Temperature Stability
Maintains performance at elevated temperatures.
Versatile Service Range
Performs from cryogenic temperatures to approximately 980°C.
Limitations
Higher Cost Than Stainless Steel
Nickel and molybdenum content increase material cost.
Difficult Machining
Work hardening can increase tooling wear.
Heavier Than Titanium
Higher density limits weight-sensitive designs.
Lower Strength Than Inconel 718
Not ideal for the most demanding aerospace structural applications.
Comparison with Other Nickel Alloys
| Property | Inconel 625 | Inconel 600 | Inconel 718 |
|---|---|---|---|
| Corrosion Resistance | Outstanding | Excellent | Excellent |
| Tensile Strength | High | Moderate | Very High |
| Weldability | Outstanding | Excellent | Good |
| Marine Resistance | Outstanding | Good | Excellent |
| Cost | High | Moderate | High |
Comparison with Common Engineering Materials
| Material | Density | Tensile Strength | Corrosion Resistance |
|---|---|---|---|
| Inconel 625 | 8.44 g/cm³ | 827 MPa | Outstanding |
| Inconel 600 | 8.47 g/cm³ | 550 MPa | Excellent |
| 316L Stainless Steel | 8.00 g/cm³ | 485 MPa | Good |
| Titanium Grade 5 | 4.43 g/cm³ | 895 MPa | Excellent |
Available Surface Finishes
Raw Finishes
- Mill Finish
- Annealed Finish
- Pickled Finish
Functional Finishes
- Precision Machined Finish
- Brushed Finish
- Polished Finish
Specialty Finishes
- Electropolished Finish
- Passivated Finish
- Offshore Service Finish
Frequently Asked Questions (FAQ)
What is Inconel 625?
Inconel 625 is a nickel-chromium-molybdenum-niobium superalloy known for exceptional corrosion resistance and high strength.
What is Inconel 625 used for?
Typical applications include:
- Offshore Equipment
- Aerospace Components
- Chemical Processing Systems
- Marine Hardware
- Heat Exchangers
What is the equivalent material to Inconel 625?
Common equivalents include:
- UNS N06625
- DIN 2.4856
- NiCr22Mo9Nb
- NS336
What is the difference between Inconel 625 and Inconel 600?
| Property | Inconel 625 | Inconel 600 |
|---|---|---|
| Strength | Higher | Lower |
| Corrosion Resistance | Better | Excellent |
| Marine Performance | Outstanding | Good |
| Molybdenum Content | Present | None |
Is Inconel 625 corrosion resistant?
Yes. It offers outstanding resistance to pitting, crevice corrosion, chloride attack, and seawater exposure.
Can Inconel 625 be welded?
Yes. Inconel 625 is one of the most weldable nickel-based superalloys.
Why choose Inconel 625?
Because it combines:
- Outstanding Corrosion Resistance
- High Strength
- Excellent Weldability
- Superior Fatigue Resistance
- Marine and Offshore Durability
Is Inconel 625 suitable for offshore applications?
Yes. It is one of the most widely specified alloys for subsea and offshore equipment.
Does GCNOV provide custom manufacturing services for Inconel 625?
Yes. GCNOV provides:
- CNC Machining
- Precision Turning and Milling
- Nickel Alloy Fabrication
- Welding Services
- Surface Finishing
- Prototype Development
- Low-Volume Production
- Mass Production