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Steel for boiler heating surface pipes and steam pipes
Source:Xinsteel Date:2020/4/10
The following introduces some commonly used pot materials according to the superheater and steam pipe wall temperature (working temperature).
(1) Wall temperature: superheater tube≤500 ℃, steam pipeline≤450 ℃.
Commonly used steel: 20# steel, German st35.8, st45.8, etc.
Heat treatment: hot rolling, air cooling.
Advantages and disadvantages: good manufacturability and low price; pearlite spheroidization and graphitization will occur.
(2) Wall temperature: superheater tube ≤550 ℃, steam pipeline ≤510 ℃.
Commonly used steel: 15CrMoG.
Heat treatment: 930 ~ 960 ℃ normalizing, 680 ~ 730 ℃ tempering.
Advantages and disadvantages: no graphitization tendency; pearlite spheroidization and alloy redistribution will occur.
(3) Wall temperature: superheater tube ≤580 ℃, steam pipeline ≤540 ℃.
Commonly used steel: 12Cr1MoVG, West Germany 10CrMo910, 2.25Cr1Mo, etc.
Heat treatment: normalizing + high temperature tempering, air cooling at 980 ~ 1020 ℃, tempering at 720 ~ 760 ℃ for 3h.
Advantages and Disadvantages: There is sufficient oxidation resistance; there is a certain degree of thermal brittleness, redistribution of pearlite and alloy elements will occur.
(4) Wall temperature: superheater tube and steam pipeline ≤600 ~ 620 ℃.
Commonly used steel: 12Cr2MoWVTiB (ie steel 102).
Heat treatment: normalizing + high temperature tempering to obtain bainite structure.
Advantages and Disadvantages: Interaction of various trace elements, better thermal strength and tissue stability, no thermal brittleness; poor welding performance, insufficient quality, rarely used steam pipes, mostly used in superheaters and reheaters.
At present, the further development of new heat-resistant materials that are both high-temperature resistant and inexpensive is the key to the development of high-parameter units.
