Selection of materials at high temperatures of 350°C
Thread Content
There is currently one product whose design temperature is 350°C; the materials used are Q345R for plates and 16Mn for forgings. The plates and forgings are subjected to high-tension testing at 350°C in accordance with GB150. There are the following questions: 1. Is the material selection for the plates and forgings appropriate? Or should chromium-molybdenum steel be chosen? 2. I’m not sure which material to choose for the take over, as this equipment will operate in an environment with a low temperature of -15.5°C; initially, Q345D was selected. However, no corresponding high-tensile data can be found in GB150. I hope fellow sailors will feel free to share their advice. Thank you!
The high-temperature tensile property parameters of Q345R (ReL or RP0.2) are in accordance with material standards and GB150
If there are no low-temperature operating conditions, chromium-molybdenum steel can be chosen; in the presence of such conditions, the owner’s proposal is feasible, and it’s also fine to use Q345D steel for the pipes. The steel pipe standard referenced in the new 150 is the old GB6479; 16Mn corresponds to the four categories Q345BCDE in the new standard.
Thank you. Information on Q345R and 16Mn forgings is available, but I’m not sure where to find information on Q345D
Does that mean the values for Q345D can be taken from those of 16Mn?
The value for 16Mn can be used as a reference.
At 1,350℃, Q345R and 16Mn forgings can be used, provided that the process medium permits it and temperature is not an issue. Personally, I don’t think it’s necessary to conduct high-temperature stretching tests; unless the plate thickness exceeds 50 mm, there’s no need to consider it. 2. How does it occur at low temperatures? I guess it’s the ambient temperature; first figure out whether the device’s operation is affected by ambient temperature before considering whether it’s necessary to take low temperatures into account. If there are no conditions involving low temperatures, then this ambient temperature can be ignored.
Do Q345R and 16Mn forgings require high-temperature tensile testing? :L has previously designed many Q345R devices with design temperatures of 300+ degrees, and never considered high-temperature tensile testing; I would appreciate some advice! In the case of low-temperature operating conditions, for Q345R, the impact temperature is determined based on thickness and GB150.2; it’s unlikely that 16Mn forgings can withstand an impact temperature of -20°C. Low-temperature pipes Q345D are permitted for use under our inspection regulations.
The high-temperature tensile properties of Q345D material can be based on the data for 16Mn pipes
Are there any standards specifying at what temperatures high-temperature stretching must be performed? I’m not really familiar with this area. Based on experience, it’s inevitable that there will be an excess of quality. Also, since it is designed by a manufacturing factory, customer requests must be met as long as they do not violate the standards. Low temperature is indeed also an environmental factor.