Design and application issues of 16MnR under high-temperature service conditions
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A heat exchanger is now being designed with an operating temperature range of 25–420°C and a design temperature of 430°C. We recommend using 15CrMoR for the shell; however, the user may specify the use of 16MnR (i.e., Q345R). According to GB150, the allowable stress for 16MnR at 430°C is 87.6 MPa. Which high-temperature mechanical property does this allowable stress correspond to – the yield strength at 430°C or the creep limit? Is it necessary to specify this high-temperature mechanical property value when specifying the material requirements? Can steel mills provide the high-temperature creep limit?
This post was last edited by realben on 2010-3-25 at 11:14. The allowable stress of 16MnR at 430 degrees is half that at room temperature, and the wall thickness increases significantly. I wonder if you think this is appropriate; personally, I believe Cr-Mo steel can be recommended for temperatures above 300 degrees. In an environment with sulfur corrosion, Cr-Mo steel also possesses certain corrosion resistance. Putting aside strength, carbon steel tends to graphitize and spheroidize its pearlite when used at high temperatures of 400 degrees for an extended period; it’s not worth the constant worry over saving on material costs. The designer has an obligation to provide users with more reasonable suggestions, after all, they bear the primary responsibility in case something goes wrong. High-temperature mechanical properties can be specified as additional conditions when ordering steel plates, but conducting equivalent tests for the high-temperature creep limit is rather troublesome.
Above 400 degrees, you need to be very careful~~~