In the process of heat-resistant castings used in the temperature in 200 degrees, the pressure is only 0.8MPa, now with the use of all kinds of power equipment, temperature rising, rapidly increasing working pressure, the use of modern temperature heat resistant steel has been as high as 700 DEG C, the use of the environment has become more complex and demanding the use of temperature. The range of heat-resistant castings is 200~1300 DEG C, working pressure of several to tens of MPA MPa, the working environment from the oxidizing atmosphere alone, to the development of sulfide atmosphere, mixed atmosphere and molten salt and liquid metal in more complex environments.
Classification of heat resistant castings according to the content of alloy elements
1. low carbon steel: it contains or rarely contains other alloy elements in the middle of this kind of steel, and its carbon content is generally not more than 0.2%..
2. low alloy heat resistant steel: all kinds of alloy elements are contained in such steel, but the content is not high. The total alloy elements in common steel are not more than 5%, and the carbon content is less than 0.2%..
3. high alloy heat-resistant steel. In this type of alloying elements in steel, the content of alloy elements in general more than 10%, or even more than 30%.
Heat resistant castings classified according to the properties of steel
1.: this kind of steel oxidation resistant steel at high temperatures (generally at 550~1200 DEG C) has better oxidation resistance and corrosion resistance, and high temperature strength. For certain parts and all kinds of heating furnace heat exchanger manufacturing, combustion, producing heat steam turbine boiler heating furnace and furnace bottom respectively, and the roller tube etc. is the main index. The antioxidant properties, component itself is not under great pressure.
2. heat resistant steel at high temperature (usually at 450~900 DEG C) can withstand considerable additional stress but also has excellent oxidation resistance, high-temperature gas corrosion, usually also variable requirements under periodic stress. Often used as a steam turbine rotor blade of gas turbine, boiler superheater, bolts and spring work under high temperature, the exhaust valve of an internal combustion engine, oil hydrogenation reactor.http://www.wuxiorient.com/