Alloy steel with high strength and good chemical stability at high temperatures. It includes two types of anti-oxidation steel (or high-temperature non-skinned steel) and hot-strength steel. Anti-oxidation steel generally requires better chemical stability, but bears lower loads. Hot-strength steel requires higher high-temperature strength and corresponding oxidation resistance. Heat-resistant steel is often used to manufacture parts and components that work at high temperatures in industrial sectors such as boilers, steam turbines, power machinery, industrial furnaces, and aviation and petrochemical industries. In addition to high-temperature strength and high-temperature oxidation and corrosion resistance, these parts also require sufficient toughness, good workability and weldability, and a certain degree of structural stability according to different uses. In addition, some new low-chromium-nickel anti-oxidation steel grades have been developed.
Heat-resistant steel can be divided into two types: oxidation-resistant steel and heat-strength steel according to its properties. Anti-oxidation steel is also referred to as non-skinned steel. Heat-strength steel refers to steel that has good oxidation resistance and high high-temperature strength at high temperatures.
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.
Heat-resistant steel is often used to manufacture parts and components that work at high temperatures in industrial sectors such as boilers, steam turbines, power machinery, industrial furnaces, and aviation and petrochemical industries. In addition to high-temperature strength and high-temperature oxidation and corrosion resistance, these parts also require sufficient toughness, good workability and weldability, and a certain degree of structural stability according to different uses. China has been producing heat-resistant steel since 1952. In the future, some new low-alloy heat-strength steels were developed, so that the working temperature of pearlitic heat-strength steels was increased to 600~620℃; in addition, some new low-chromium-nickel anti-oxidation steels were also developed.
Heat-resistant steel and stainless acid-resistant steel cross each other in the scope of use. Some stainless steels have the characteristics of heat-resistant steel and can be used as stainless acid-resistant steel or heat-resistant steel.
Folded pearlitic steel
The alloying elements are mainly chromium and molybdenum, and the total amount generally does not exceed 5%. In addition to pearlite and ferrite, its structure also has bainite. This kind of steel has good high temperature strength and process performance at 500~600℃, and the price is relatively low. It is widely used to make heat-resistant parts below 600℃. Such as boiler steel pipes, steam turbine impellers, rotors, fasteners and high-pressure vessels, pipelines, etc. Typical steel grades are: 16Mo, 15CrMo, 12Cr1MoV, 12Cr2MoWVTiB, 10Cr2Mo1, 25Cr2Mo1V, 20Cr3MoWV, etc.
Folded Martensitic Steel
The chromium content is generally 7~13%, and it has higher high temperature strength, oxidation resistance and water vapor corrosion resistance below 650℃, but the weldability is poor. 1Cr13, 2Cr13 with about 12% chromium, and steel grades developed on this basis, such as 1Cr11MoV, 1Cr12WMoV, 2Cr12WMoNbVB, etc., are usually used to make steam turbine blades, discs, shafts, fasteners, etc. In addition, 4Cr9Si2, 4Cr10Si2Mo, etc. used in the manufacture of exhaust valves for internal combustion engines are also martensitic heat-resistant steels.
Folded ferritic steel
Contains more chromium, aluminum, silicon and other elements to form a single-phase ferrite structure. It has good oxidation resistance and high temperature gas corrosion resistance, but it has low high temperature strength, high room temperature brittleness, and poor weldability. Such as 1Cr13SiAl, 1Cr25Si2, etc. It is generally used to make parts that bear low load and require high temperature oxidation resistance.
Folded austenitic steel
Contains more austenite forming elements such as nickel, manganese, nitrogen, etc., when the temperature is above 600 ℃, it has better high temperature strength and structural stability, and good welding performance. It is usually used as a heat-strength material that works above 600°C. Typical steel grades include 1Cr18Ni9Ti(321), 1Cr23Ni13(309), 0Cr25Ni20 (310S), 1Cr25Ni20Si2(314), 2Cr20Mn9Ni2Si2N, 4Cr14Ni14W2Mo and so on.
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