Research on the High-Temperature Oxidation Resistance of Stainless Steel Sheets in New Energy Devices

Research on the High-Temperature Oxidation Resistance of Stainless Steel Sheets in New Energy Devices

With the global energy structure transitioning toward green and low-carbon development, new energy devices (such as solar thermal power generation, hydrogen energy, nuclear energy, and high-efficiency energy storage systems) are developing rapidly. These devices often operate in high temperatures, high pressures, and complex corrosive environments, placing extremely high demands on the performance of key structural materials. Stainless steel sheets, due to their excellent overall performance, have become the material of choice for many new energy devices. However, their oxidation resistance in high-temperature environments directly determines the lifespan, efficiency, and safety of these devices, making in-depth research crucial.

1. Performance Requirements of Stainless Steel Sheets for New Energy Devices
New energy devices operate in demanding environments, such as:

① Solar thermal power generation: Concentrated solar collector systems require materials to operate stably and for extended periods at temperatures between 400°C and 800°C, while withstanding thermal fatigue caused by temperature swings between day and night.

② Hydrogen energy technology: Bipolar plates in water electrolysis hydrogen production equipment and interconnects in SOFCs (solid oxide fuel cells) operate at high temperatures and in environments with oxidizing/reducing atmospheres.

③ Nuclear energy: Next-generation reactors (such as molten salt reactors) require materials that are resistant to corrosion and oxidation from high-temperature molten salts.

④ Large-capacity energy storage: Some thermal energy storage systems also involve high-temperature media.

In these applications, materials require not only excellent mechanical strength and processability, but also high-temperature oxidation resistance as a key performance indicator. Oxidation can reduce the effective cross-section of the material and degrade mechanical properties. Oxide scale flaking can also block flow channels or contaminate the media, causing equipment failure.

2. High-temperature Oxidation Resistance of Stainless Steel Plates
Stainless steel's oxidation resistance stems from the dense oxide film that forms on its surface. This film effectively blocks oxygen diffusion, thereby slowing further oxidation. The core mechanism is as follows:

The Key Role of Chromium (Cr): Chromium is the most critical alloying element. When the chromium content reaches a certain level (generally considered above 12%), it selectively oxidizes at high temperatures, forming a Cr₂O₃ (chromium trioxide)-rich passivation film on the surface. This film is extremely dense and stable, serving as the primary barrier against high-temperature oxidation.

Strengthening with Other Alloying Elements:

Silicon (Si) and Aluminum (Al): These elements form more stable SiO₂ or Al₂O₃ films, further raising the oxidation resistance limit temperature. However, excessive addition may affect workability.

Rare earth elements (such as Ce and Y): Small additions can significantly improve the adhesion of the oxide film, preventing it from flaking due to thermal cycling (improving spalling resistance).

Nickel (Ni): Primarily improves austenite stability, enhancing high-temperature strength and carburization resistance.

Oxide film growth and destruction: The oxidation process is dynamic. An ideal oxide film grows slowly and adheres firmly. However, under thermal cycling or certain corrosive media, the film may crack and flake, resulting in a loss of oxidation resistance and a sharp increase in the oxidation rate.

3. Common Types of Stainless Steel Plates Used in New Energy Equipment and Their Performance
Different types of stainless steel have different oxidation resistance properties due to their compositional differences:

① Austenitic Stainless Steel:

304/304H Stainless Steel: As general-purpose austenitic stainless steels, they offer excellent oxidation resistance below 700°C and are commonly used in heat exchange components operating at slightly lower temperatures.

321 Stainless Steel (Ti-added) and 347 Stainless Steel (Nb-added):
The addition of Ti or Nb stabilizes carbides, preventing intergranular corrosion and further improving resistance to high-temperature oxidation and creep, enabling an application temperature of approximately 800°C.

310S Stainless Steel: With its high chromium (approximately 25%) and nickel (approximately 20%) content, it is a classic heat-resistant steel capable of continuous operation below 1000°C. It offers excellent oxidation resistance and is commonly used in key components such as high-temperature collector tubes in solar thermal power generation.

② Ferritic stainless steel:

Such as 446, these contain high chromium (approximately 25%), offer excellent oxidation resistance and are relatively low in cost. However, their high-temperature strength and structural stability are inferior to austenitic steels, and they are primarily used for heat-resistant components subjected to low stresses.

③ High-performance austenitic stainless steels and alloys:

For more extreme environments, materials such as 253MA, 800H/HT, and even 625 alloy are used. These achieve excellent oxidation resistance and creep properties above 1100°C through precise control of carbon, nitrogen, and rare earth elements.

4. Current Research Directions and Improvement Strategies
To meet the demand for higher efficiency (i.e., higher operating temperatures) in future new energy devices, research is being conducted on multiple dimensions to enhance the high-temperature oxidation resistance of stainless steel:

① Microalloying Optimization: In-depth research is being conducted on the effects of rare earth elements, trace amounts of magnesium, and calcium on the cohesion and growth kinetics of oxide films, aiming to achieve superior performance at a lower cost.

② Surface Treatment Technology: Through pre-oxidation (pre-forming a more stable and dense oxide film in a controlled atmosphere), coating techniques (such as spraying MCrAlY coating), or surface nano-crystallization, a stronger protective barrier is constructed on the substrate surface without changing the substrate's overall performance.

③ Advanced Manufacturing Processes: Using technologies such as powder metallurgy and additive manufacturing (3D printing), high-performance stainless steel components with more uniform composition and finer microstructure are produced, reducing defects and thus improving overall oxidation resistance.

Long-Term Performance Evaluation and Prediction: High-temperature exposure and thermal cycling tests lasting thousands of hours are conducted in environments simulating actual operating conditions. Combined with analytical methods such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), the evolution and failure mechanisms of the oxide film are thoroughly studied, and a life prediction model is established.

5. Conclusion
In the strategic field of new energy, which is crucial to future development, stainless steel plate, as a fundamental and critical material, is crucial for the development of high-temperature oxidation resistance. Research on its high-temperature oxidation resistance is crucial for driving technological advancements in equipment and improving efficiency and reliability. From classic 310S to a new generation of high-performance stainless steel optimized through microalloying and surface engineering, innovations in materials science and engineering are continuously pushing the boundaries of both operating temperature and lifespan. Continuously deepening our understanding of oxidation mechanisms and developing more economical and durable stainless steel materials will provide a solid foundation for the long-term, safe, and stable operation of new energy equipment such as solar thermal power generation, hydrogen energy, and nuclear energy, contributing to the realization of global energy transition goals.