Inconel 690丨UNS N06690
Inconel 690 (Alloy 690 / UNS N06690) is a high-chromium nickel alloy engineered for exceptional resistance to oxidation, high-temperature corrosion, and chloride-induced stress corrosion cracking. With approximately 30% chromium, it provides significantly improved corrosion resistance compared with Inconel 600, making it a preferred material for nuclear steam generators, heat exchangers, chemical processing equipment, and high-temperature industrial applications. J&A Alloy supplies Inconel 690 in pipe, tube, plate, sheet, bar, flange, and fitting forms with full material traceability and EN 10204 3.1 certification.
Inconel 690 (Alloy 690 / UNS N06690)
Inconel 690, also known as Alloy 690 or UNS N06690, is a nickel-chromium alloy specifically developed to provide superior resistance to oxidizing environments, high-temperature corrosion, and chloride stress corrosion cracking. The alloy contains approximately 30% chromium—substantially higher than Inconel 600—which significantly improves resistance to oxidation, carburization, and aqueous corrosion.
Because of its excellent corrosion resistance and thermal stability, Inconel 690 has become the industry standard material for nuclear steam generator tubing and critical components in power generation systems. The alloy also performs exceptionally well in nitric acid service, high-temperature oxidizing atmospheres, and sulfur-containing environments. Its combination of mechanical strength, metallurgical stability, and long-term corrosion resistance makes it suitable for demanding applications in nuclear power, chemical processing, thermal processing, and pollution control industries.
J&A Alloy supplies Inconel 690 products in a full range of forms, including seamless and welded pipes, tubes, plates, sheets, bars, flanges, and fittings for global industrial projects.
Features of Inconel 690
- Excellent resistance to chloride stress corrosion cracking.
- Outstanding oxidation resistance at elevated temperatures.
- Superior resistance to high-temperature corrosion.
- Excellent resistance to nitric acid and oxidizing acids.
- Improved corrosion resistance compared with Inconel 600.
- Good resistance to carburization and nitriding.
- High metallurgical stability during long-term service.
- Excellent mechanical properties across a wide temperature range.
- Good fabrication and welding characteristics.
- Widely approved for nuclear and power generation applications.
Chemical Composition of Inconel 690
| Element | Content (%) |
|---|---|
| Nickel (Ni) | ≥ 58.0 |
| Chromium (Cr) | 27.0 – 31.0 |
| Iron (Fe) | 7.0 – 11.0 |
| Carbon (C) | ≤ 0.05 |
| Manganese (Mn) | ≤ 0.50 |
| Silicon (Si) | ≤ 0.50 |
| Sulfur (S) | ≤ 0.015 |
| Copper (Cu) | ≤ 0.50 |
Physical Properties of Inconel 690
| Property | Value |
|---|---|
| Density | 8.19 g/cm³ |
| Melting Range | 1343 – 1377°C |
| Electrical Resistivity | 1.15 μΩ·m |
| Thermal Conductivity | 13.5 W/m·K |
| Specific Heat Capacity | 444 J/kg·K |
| Modulus of Elasticity | 211 GPa |
Mechanical Properties of Inconel 690
| Property | Value |
|---|---|
| Tensile Strength | ≥ 586 MPa |
| Yield Strength (0.2% Offset) | ≥ 241 MPa |
| Elongation | ≥ 30% |
| Hardness | ≤ 95 HRB |
Corrosion Resistance
Inconel 690 is widely recognized for its exceptional resistance to chloride stress corrosion cracking and oxidizing chemical environments. Its high chromium content creates a stable protective oxide layer that significantly improves corrosion resistance compared with Inconel 600.
The alloy demonstrates excellent performance in nitric acid, high-purity water systems, nuclear steam generator environments, and oxidizing acid solutions. It also provides outstanding resistance to intergranular attack, high-temperature oxidation, and sulfur-containing atmospheres. These properties make Inconel 690 one of the most reliable materials for long-term service in highly corrosive and high-temperature applications.
High Temperature Performance
| Property | Performance |
|---|---|
| Recommended Continuous Service Temperature | Up to 1100°C |
| Oxidation Resistance | Excellent |
| Carburization Resistance | Excellent |
| Thermal Stability | Excellent |
Available Forms
| Product Form | Availability |
|---|---|
| Pipe | Seamless / Welded |
| Tube | Seamless / Welded |
| Plate | Available |
| Sheet | Available |
| Bar | Round / Flat / Hex |
| Rod | Available |
| Flange | Available |
| Pipe Fittings | Available |
Applications of Inconel 690
- Nuclear steam generator tubing
- Nuclear reactor components
- Heat exchangers
- Chemical processing equipment
- Nitric acid production
- Thermal processing systems
- Industrial furnaces
- Waste incineration systems
- Petrochemical processing
- Pollution control equipment
Inconel 690 vs Other Alloys
| Property | Inconel 690 | Inconel 600 | Inconel 625 | Alloy 800H |
|---|---|---|---|---|
| Chromium Content | 27–31% | 14–17% | 20–23% | 19–23% |
| Oxidation Resistance | Excellent | Good | Excellent | Very Good |
| Chloride SCC Resistance | Excellent | Good | Excellent | |
| Nuclear Applications | Excellent | Good | Limited | Limited |
Welding & Fabrication
Inconel 690 can be welded using GTAW (TIG), GMAW (MIG), SMAW, and other conventional nickel alloy welding processes. The alloy exhibits excellent resistance to weld-related stress corrosion cracking and maintains corrosion resistance after welding when proper procedures are followed.
Standards & Equivalent Grades
| Standard | Designation |
|---|---|
| UNS | N06690 |
| Werkstoff Number | 2.4642 |
| ASTM Bar & Rod | B166 |
| ASTM Plate, Sheet & Strip | B168 |
| ASTM Pipe & Tube | B167 / B829 |
| ASME | SB166 / SB167 / SB168 |
| Trade Name | Inconel 690 / Alloy 690 |
Frequently Asked Questions
What is Inconel 690 used for?
Inconel 690 is widely used in nuclear steam generators, heat exchangers, chemical processing equipment, nitric acid production systems, thermal processing equipment, and pollution control applications.
Why is Inconel 690 preferred over Inconel 600?
Inconel 690 contains approximately twice the chromium content of Inconel 600, providing significantly improved resistance to chloride stress corrosion cracking, oxidation, and high-temperature corrosion.
What is the difference between Inconel 690 and Inconel 625?
Inconel 690 is optimized for oxidation resistance and nuclear applications, while Inconel 625 provides higher strength and superior resistance to seawater and mixed corrosive environments.
Is Inconel 690 suitable for nuclear applications?
Yes. Inconel 690 is one of the most widely used materials for nuclear steam generator tubing and critical nuclear power plant components due to its excellent corrosion resistance and long-term stability.
Is Inconel 690 resistant to chloride stress corrosion cracking?
Yes. Inconel 690 is specifically known for its exceptional resistance to chloride-induced stress corrosion cracking, making it a preferred material for nuclear and chemical processing industries.
Is Inconel 690 resistant to nitric acid?
Yes. The alloy provides excellent resistance to nitric acid and other strongly oxidizing acids due to its high chromium content.
What temperature can Inconel 690 withstand?
Inconel 690 maintains excellent oxidation resistance and structural stability at temperatures up to approximately 1100°C, depending on operating conditions.
What is the chemical composition of Inconel 690?
Inconel 690 is a nickel-chromium alloy containing approximately 58% nickel, 27–31% chromium, and 7–11% iron, with controlled levels of carbon and other elements.
What is the UNS number of Inconel 690?
The UNS designation of Inconel 690 is UNS N06690.
Can Inconel 690 be welded?
Yes. Inconel 690 exhibits excellent weldability and can be welded using GTAW (TIG), GMAW (MIG), SMAW, and other conventional nickel alloy welding processes.
What forms are available for Inconel 690?
Inconel 690 is available in pipe, tube, plate, sheet, strip, bar, rod, flange, and fitting forms.
Which industries use Inconel 690?
Industries using Inconel 690 include nuclear power generation, chemical processing, petrochemical production, thermal processing, and pollution control.
What standards apply to Inconel 690?
Common standards include UNS N06690, W.Nr. 2.4642, ASTM B166, ASTM B167, ASTM B168, ASTM B829 and ASME SB166, SB167 and SB168.
Is Inconel 690 better than stainless steel?
For high-temperature and highly corrosive environments, Inconel 690 offers significantly better oxidation resistance, stress corrosion cracking resistance, and long-term durability than stainless steels.
Why is Inconel 690 used for steam generator tubes?
Inconel 690 provides exceptional resistance to primary water stress corrosion cracking (PWSCC), chloride stress corrosion cracking, and high-temperature oxidation, making it the industry-standard material for nuclear steam generator tubing.
Why Choose J&A Alloy
J&A Alloy specializes in supplying premium nickel alloys and high-performance corrosion-resistant materials to customers worldwide.
We provide complete material traceability, EN 10204 3.1 Mill Test Certificates, strict quality control, and global logistics support.
Our extensive inventory and technical expertise enable us to supply standard and custom dimensions for critical industrial applications, ensuring reliable performance and consistent quality for every project.
