Alloy 690 exhibits excellent resistance to intergranular corrosion and intergranular stress‑corrosion cracking, and is primarily used for heat‑transfer tubes of steam generators in pressurized‑water reactor (PWR) nuclear power plants.
The materials adopted for PWR steam generator heat‑transfer tubes have gone through an evolutionary path, including 304 austenitic stainless steel, Alloy 600, Alloy 800 and Alloy 690.
Studies of in‑service corrosion failures of Alloy 600 show that intergranular corrosion and intergranular stress‑corrosion cracking are the primary failure concerns.
Since its deployment for PWR steam generator heat‑transfer tubes in the 1990s, no damage‑related incidents involving Alloy 690 have been reported.
Inconel 690 Wire UNS N06690/NiCr30Fe/NS3105
1. Overview
2. Chemical Composition
3. Performance Characteristics
- Corrosion Resistance:
- Exhibits excellent resistance to various corrosive media, including acidic environments such as nitric acid, sulfuric acid, and phosphoric acid, as well as chloride-containing aqueous solutions.
- Particularly effective in preventing stress corrosion cracking, maintaining stability in the primary and secondary circuits of nuclear reactors, making it a crucial structural material in the nuclear industry.
- High-Temperature Performance: Maintains high strength and oxidation resistance at elevated temperatures, suitable for use in high-temperature steam and high-temperature gas environments.
- Machinability: Can be hot or cold worked with a wide hot working temperature range. After cold working, solution treatment can restore the material’s plasticity and corrosion resistance. It also has good weldability and can be joined using various welding methods.
4. Application Areas
- Nuclear Industry: It is the primary material for heat transfer tubes in nuclear reactor steam generators, transporting high-temperature and high-pressure coolants to ensure the safe operation of reactors. Additionally, it is used in other structural components of nuclear reactors, such as core support structures and control rod drive mechanisms.
- Chemical Industry: Used as the material for reaction vessels, pipelines, and heat exchangers in highly corrosive chemical production processes, such as nitric acid production and sulfuric acid concentration.
- Energy Industry: In flue gas desulfurization systems of thermal power plants, Inconel 690 can be used to manufacture absorption towers, pipelines, and other components to resist the erosion of corrosive substances like sulfur dioxide and chlorides in the flue gas.