There are many kinds of steel, but they are not identical in performance. Usually, we refer to high-temperature resistant steel as "heat-resistant steel". Heat resistant steel refers to a type of steel that has oxidation resistance, sufficient high temperature strength and good heat resistance under high temperature conditions.
Heat resistant steel is often used in the manufacture of boilers, steam turbines, power machinery, industrial furnaces, and parts and components that work at high temperatures in industrial sectors such as aviation and petrochemicals. In addition to high temperature strength and high temperature oxidation corrosion resistance, these parts also require sufficient toughness, good workability and weldability, and certain organizational stability according to different applications.
Heat resistant steel can be divided into two categories: oxidation-resistant steel and heat-strength steel according to its properties. Antioxidant steel is also referred to as non-skinned steel. Heat-strength steel refers to steel with good oxidation resistance at high temperature.
Heat-resistant steel can be divided into austenitic heat-resistant steel, martensitic heat-resistant steel, ferritic heat-resistant steel and pearlite heat-resistant steel according to its normalized structure.
Austenitic heat-resistant steel contains a lot of austenite-forming elements such as nickel, manganese, nitrogen, etc. When the temperature is above 600 °C, it has good high-temperature strength and microstructure stability, and good welding performance. It is usually used at temperatures above 600 °C.
The chromium content of martensitic heat-resistant steel is generally 7-13%, and it has high high-temperature strength, oxidation resistance and water vapor corrosion resistance below 650 °C, but its weldability is poor.
Ferritic heat-resistant steel contains more chromium, aluminum, silicon and other elements to form a single-phase ferrite structure, which has good oxidation resistance and high temperature gas corrosion resistance, but has low high temperature strength and high room temperature brittleness. , poor weldability.
The alloying elements of pearlitic heat-resistant steel are mainly chromium and molybdenum, and the total amount is generally not more than 5%. In addition to pearlite and ferrite, its microstructure also includes bainite. This kind of steel has good high-temperature strength and process performance at 500-600 °C, and the price is low, and is widely used to make heat-resistant parts below 600 °C, such as boiler steel pipes, steam turbine impellers, rotors, fasteners and high-pressure vessels, pipes, etc.
