How to define the temperature of low-temperature impact and how to determine the value of absorbed impact energy?
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GB150.2 Table 4 lower limit of service temperature of steel plate (P47). When the material is a Q245R normalized steel plate with a thickness of 6, the working temperature is -20°C, and the design temperature is -30°C, what temperature should be used for the impact energy test of the steel plate (0°C, -20°C, -30°C, or lower than -30°C)? How should the value of absorbed impact energy be determined?
The impact test temperature of the steel plate shall not be lower than the minimum design temperature. 4.3.4 a) in GB/T150.1-2011 "For metal temperatures below 0°C, the design temperature shall not be higher than the lowest possible temperature of the component metal." When selecting the minimum temperature, both the design temperature and the minimum design metal temperature must be considered. When selecting Q245R, the low-temperature impact test temperature can be taken as the lowest design temperature, and the impact absorbed energy can be taken as shown in Table 2 of GB/T713-2014. The above design temperature is -30℃. It is recommended to consider carefully when choosing Q245R. It is recommended to choose 16MnDR.
For pressure vessels made of 150°C, the minimum operating temperature of Q245R and Q345R is -20°C, and 16MnDR is required at -30°C. The "Use Temperature Lower Limit" column in Table 4 refers to the lowest temperature at which the material can only be used. If the temperature is lower than this temperature, the material must be replaced. The impact test temperature should be less than or equal to the minimum metal design temperature. For the minimum metal design temperature, please refer to HG/T 20580-2011 "Basic Regulations for the Design of Steel Chemical Vessels" ； Qualification indicators can be checked in the corresponding material standards (for example, Q245R and Q345R can be checked in GB/T713).
Design temperature -30℃, it is recommended to use 16MnDR
Does the service temperature in Table 4 of GB150.2 refer to the design temperature or the operating temperature?
However, Table 4 of GB150.2 gives impact energy at different temperatures. For example, if a normalized plate with a thickness of 6 mm Q245R at -20°C is used, only 0°C impact energy is required. Have you misunderstood this table or misunderstood the clause "The impact test temperature of the steel plate shall not be lower than the minimum design temperature"”
-At 30℃, it seems that Q245R and 345R cannot be used, right? The materials should be selected according to the design temperature, right? ?
It is said in the explanation of the article that the properties of thin steel plates are easier to control than thick steel plates, and the structure is more uniform, so 0°C impact steel plates can be used at lower temperatures. The minimum allowable use temperature of steel plates can be selected according to this table.
-At 30℃, Q245R material should also be selected, unless it is a low temperature and low stress working condition. The toughness of 6mmQ245R is inherently better, so there is no need to conduct impact tests under low temperature and low stress conditions. The impact test temperature of the material is determined according to the design temperature.
-At 30℃, Q245R material should also be selected. In other words, your design does not comply with GB/T150 regulations. So can your product be sold?
I am asking the question using an example, not that I use Q245R in this situation.