Regarding the issues with GB24511 sheets (asking on behalf of a friend)
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Standard GB24511-2009 defines three types of materials: hot-rolled heavy steel plates denoted as P, hot-rolled steel plates and strips denoted as H, and cold-rolled steel plates and strips denoted as C. The thickness ranges for these materials overlap; for example, a thickness of 6–8 mm can fall under all three categories. I would like to ask how this is generally handled in such cases – which type should be chosen? The requirements regarding thickness tolerances vary for each of these three types.
Check the requirements of the specific application product. It mainly comes down to the difference in surface condition: cold-rolled C obviously has the best surface quality and the smallest tolerances, followed by hot-rolled H, and lastly, medium-thick plate P. Of course, the prices vary as well; cold-rolled C and medium-thick plate P are both relatively expensive. Medium-thick plate C is produced in single sheets, and factors such as yield and production efficiency mean that its price is often even higher than that of C; it is generally used for thicknesses of 6–8 because of the difficulties involved in manufacturing the material and considerations related to its properties. Hot-rolled H is usually cheaper, which is why it is the most commonly used in container production. For some common containers used in medical devices and food processing machinery, or for certain components that sometimes require surface polishing later on, cold-rolled C is chosen due to the high requirements for the surface quality; in most cases, H is sufficient.
We all work with equipment and containers, primarily using hot-rolled thick steel plates. The thickness deviation also meets industry requirements.