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Alloy element content of heat-resistant castings and classification of steel characteristics

Apr 18, 2018

In the process of using heat-resistant castings, the temperature of the heat-resistant castings is generally about 200 degrees, and the pressure is only 0.8 MPa. Now, with the increasing use temperature of various types of power devices, the working pressure increases rapidly, and the operating temperature of modern heat-resistant steel is increased. Already up to 700°C, the use of the environment has become more complex and demanding. The temperature range of heat-resistant castings is 200 to 1300°C, and the working pressure is from several megapascals to several tens of megapascals. The working environment ranges from simple oxidizing atmospheres to vulcanizing atmospheres, mixed atmospheres, and molten salt and liquid metals. surroundings.

Heat-resistant castings classified by alloying element content

1. Low-carbon steel: In the middle of this kind of steel contains or little other alloying elements, its carbon content is generally not more than 0.2%.

2. Low-alloy heat-resistant steel: In this kind of steel contains one or more alloying elements, but the content is not high, the total amount of alloying elements contained in steel generally does not exceed 5%, carbon content does not exceed 0.2%.

3 high-alloy heat-resistant steel: In this type of steel alloy elements, alloying element content is generally more than 10%, or even as high as 30% or more.

Heat-resistant castings are classified according to the characteristics of the steel

1. Anti-oxidation steel: This kind of steel has good oxidation resistance and high temperature corrosion resistance under high temperature (usually at 550 ~ 1200 °C), and has certain high temperature strength. It is used to make various types of heating furnace parts and heat exchangers, to manufacture the combustion turbines of hot steam turbines, boiler hangings, heating furnace bottom plates and roller tables, and furnace tubes. Antioxidant performance is the main indicator, and the parts themselves are not under great pressure.

2. Hot-strength steel: At high temperatures (usually at 450-900°C), it can not only withstand considerable additional stress but also has excellent anti-oxidation and high-temperature gas corrosion resistance. It is usually required to withstand cyclical variable stress. It is commonly used as a turbine and gas turbine rotor and blade, boiler superheater, bolts and springs working under high temperature, intake and exhaust valves of internal combustion engines, and petroleum hydrogenation reactors.http://www.dmgcastings.com/