What Is Heat Resistant Steel?
Heat-resistant steel (SUH = Steel Use Heat) is a type of alloy steel used to maintain oxidation resistance, corrosion resistance, and strength in environments exposed to high temperatures.
It contains elements such as chromium, nickel, tungsten, and cobalt. It is classified into four types according to its structure: austenitic, martensitic, ferritic, and precipitation hardening.
Heat-resistant steel includes not only steel but also stainless steel (SUS) containing chromium.
Uses of Heat Resistant Steel
Heat-resistant steel maintains its strength at high temperatures, making it a primary choice for applications such as engine valves, turbine blades, furnaces, burners, and other components that are consistently exposed to high heat.
It is also used in disc brakes for automobiles and motorcycles to withstand frictional heat. Furthermore, it is widely used in rotor shafts, bolts, bearings, and other indispensable components in automobile manufacturing.
Applications and properties vary depending on the chromium and nickel content.
Characteristics of Heat Resistant Steel
Heat-resistant steel has four types of structures: austenitic, martensitic, ferritic, and precipitation hardening, each of which has different applications and properties.
Austenitic steels are composed of chromium steel with nickel added. They maintain their microstructure even at room temperature and are characterized by excellent corrosion resistance. It is used in household products, construction, LNG tanks, nuclear facilities, etc.
The martensitic type is a microstructure obtained by cooling austenite rapidly and is characterized by hardness and brittleness. Due to its wear resistance, it is used for bearing components within bearings and for blades.
The ferritic type is inexpensive because it does not contain nickel, but it has the disadvantage of inferior corrosion resistance and strength compared to the austenitic type. It is used for indoor kitchen equipment that does not require much corrosion resistance.
Precipitation hardening type is characterized by low distortion due to heat treatment at low temperatures while maintaining strength, and is less prone to age-related deterioration, such as baking cracks caused after heat treatment.