Performance classification of heat-resistant steel

Heat resistant steel is an alloy steel with high strength and good chemical stability at high temperatures, and its performance classification is mainly based on its structural characteristics and application scenarios.

Heat resistant steel is mainly divided into two categories: heat strong steel and heat stable steel. Hot strength steel is used in the temperature range of 450 to 900 degrees Celsius, which not only has good oxidation and corrosion resistance, but also exhibits good creep resistance and fracture strength, especially suitable for fatigue stress environments under cyclic loading. This type of steel is mainly used in key components such as rotors and blades of steam turbines and gas turbines, cylinders and bolts for high-temperature operation, and superheaters of boilers.

Heat stable steel, also known as anti-oxidation steel, is typically used in high-temperature environments ranging from 500 to 1200 degrees Celsius (some up to 1300 degrees Celsius). Its main characteristics are excellent oxidation resistance and corrosion resistance, while maintaining appropriate strength. Anti oxidation steel promotes the formation of a dense oxide film on the metal surface at high temperatures by adding elements such as chromium, aluminum, and silicon, effectively preventing further oxidation. These elements play a key role in improving the oxidation resistance and high-temperature gas corrosion resistance of steel. However, excessive aluminum and silicon content may reduce the room temperature plasticity and thermoplasticity of steel.

In addition, according to the metallographic structure of heat-resistant steel, it can be further subdivided into austenite type, ferrite type, martensite type, and pearlite type. Various heat-resistant steels exhibit unique performance advantages in high-temperature environments due to their unique organizational structures and alloy element ratios. They are widely used in fields such as boilers, steam turbines, power machinery, industrial furnaces, as well as aviation, petrochemicals, etc., to meet the manufacturing needs of components under various high-temperature working conditions.