Inconel 690
Supplied by Huaxiao-Alloy – Your Trusted Global Alloy Partner
1. Introduction to Inconel 690
Inconel 690 is a nickel chromium alloy designed for exceptional resistance to high temperature oxidation, hot corrosion, and aggressive aqueous environments. It is especially notable for its very high chromium content (around 30 percent), which gives it superior protection against oxidizing chemicals and hot gases compared with other Inconel grades.
At Huaxiao-Alloy, we supply Inconel 690 in various forms, including plates, sheets, bars, pipes, tubes, wires, and custom machined parts. With decades of experience in specialty alloys, our team ensures that every delivery meets strict ASTM and international quality standards, making us a trusted partner for industries worldwide.
2. Chemical Composition of Inconel 690
| Element | Typical wt.% | Function |
|---|---|---|
| Nickel (Ni) | ≥58 | Base element, corrosion resistance, structural stability |
| Chromium (Cr) | 27–31 | Provides superior resistance to oxidation and hot corrosion |
| Iron (Fe) | 7–11 | Balances structure, improves fabricability |
| Carbon (C) | ≤0.05 | Low carbon prevents sensitization |
| Silicon (Si) | ≤0.5 | Enhances oxidation resistance |
| Manganese (Mn) | ≤0.5 | Aids in deoxidation |
| Sulfur (S) | ≤0.015 | Controlled impurity |
| Copper (Cu) | ≤0.5 | Minor corrosion resistance |
| Titanium (Ti) | ≤0.5 | Grain boundary stability |
| Aluminum (Al) | ≤0.5 | Improves oxidation resistance |
The high chromium content makes Inconel 690 one of the most oxidation-resistant Inconel alloys, suitable for nuclear, chemical, and high-temperature service environments.
3. Mechanical Properties of Inconel 690
| Property | Value |
|---|---|
| Density | 8.19 g/cm³ |
| Melting Range | 1343–1377 °C |
| Tensile Strength (Room Temp) | 620–760 MPa |
| Yield Strength (0.2 percent offset) | 240–310 MPa |
| Elongation | 30–45 percent |
| Hardness | 70–80 HRB |
| Oxidation Resistance | Excellent up to 1200 °C |
These properties allow Inconel 690 to maintain mechanical stability at high temperatures and perform in both oxidizing and corrosive environments.
4. Key Features of Inconel 690
High chromium content provides exceptional oxidation and hot corrosion resistance.
Excellent resistance to chloride-induced stress corrosion cracking.
Good metallurgical stability in nuclear steam generator applications.
Superior high-temperature strength and creep resistance.
Weldability and fabricability with standard nickel alloy practices.
Long service life in harsh chemical and high-temperature settings.
5. Heat Treatment
Inconel 690 is typically supplied in the annealed condition.
Annealing temperature: 1010–1090 °C, followed by water quenching.
This heat treatment enhances corrosion resistance and mechanical ductility.
Stress relief is performed at lower temperatures (around 870 °C).
6. Applications of Inconel 690
6.1 Nuclear Power
Steam generator tubing in pressurized water reactors
Nuclear fuel processing components
Heat exchanger tubes in nuclear power plants
6.2 Chemical Processing
Equipment handling nitric acid, chromic acid, and mixed oxidizing agents
Reactors and scrubbers exposed to aggressive chemical conditions
Heat exchangers in corrosive chemical environments
6.3 High Temperature Engineering
Furnace components exposed to oxidizing gases
Gas turbine combustion liners
Superheater and reheater tubes
6.4 Pollution Control Systems
Flue gas desulfurization systems
Incinerator components
Stack liners and absorber towers
6.5 Marine Applications
Offshore heat exchangers exposed to seawater
Condensers and piping systems
7. Advantages of Inconel 690
Superior oxidation resistance compared to Inconel 600 and 625.
Chloride SCC resistance, making it suitable for seawater and chloride-rich environments.
Excellent thermal stability, retaining strength at elevated temperatures.
Weldability, with minimal risk of sensitization due to low carbon content.
Cost efficiency in long-term operations due to extended service life.
8. Limitations of Inconel 690
Higher initial cost compared to stainless steels and standard Inconel grades.
Availability may be less than more common alloys like Inconel 625.
Machining requires rigid setups due to work hardening.
9. Comparison with Other Alloys
| Alloy | Strengths | Limitations | Typical Applications |
|---|---|---|---|
| Inconel 600 | Oxidation and heat resistance | Lower chromium, weaker in aggressive oxidizing environments | Heat treating, furnace parts |
| Inconel 625 | Excellent general corrosion resistance, weldable | Not as resistant to hot corrosion as 690 | Marine, aerospace |
| Inconel 690 | High chromium, superior oxidation resistance | More expensive | Nuclear, chemical, high-temp |
| Hastelloy C276 | Excellent resistance to reducing acids | Less strength at high temp | Chemical processing |
10. Standards and Specifications
UNS Number: N06690
W. Nr.: 2.4642
Standards:
ASTM B166 (Bars, Rods, Wire)
ASTM B168 (Plates, Sheets, Strips)
ASTM B163/B167 (Seamless Tubes and Pipes)
ASTM B829 (General Requirements for Nickel Alloys)
11. Product Forms Supplied by Huaxiao-Alloy
Huaxiao-Alloy provides Inconel 690 in:
Sheets and Plates
Strips and Foils
Bars and Rods
Seamless and Welded Pipes & Tubes
Wires and Mesh
Forgings and Rings
Custom Machined Components
We guarantee products with ISO 9001 certification, full mill test reports, and third-party inspection when required.
12. Fabrication and Processing
Forming: Can be hot-formed at 870–1175 °C. Cold forming requires intermediate annealing.
Welding: Best with Inconel filler metals 82 or 92. Post-weld annealing enhances corrosion resistance.
Machining: Requires sharp tooling and slow speeds to handle work hardening.
Heat Treatment: Usually annealed before use for maximum corrosion resistance.
13. Why Choose Huaxiao-Alloy for Inconel 690
At Huaxiao-Alloy, we deliver more than just materials—we provide solutions:
Global stock availability for fast delivery
Competitive pricing with strong supplier networks
Expertise in nickel alloy fabrication
Customized dimensions and processing services
Dedicated technical support for challenging applications
📩 Email: [email protected]
📱 WhatsApp: +1 (579) 300-2733
Inconel 690 contains much higher chromium, giving it far better oxidation and corrosion resistance.
It is widely used in nuclear power, chemical processing, and high-temperature engineering.
Yes, due to its high chromium content, it resists chloride-induced stress corrosion cracking.
It can withstand oxidation and hot corrosion up to 1200 °C.
Yes, we supply custom machined components and provide fabrication support.
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