Questions about eliminating residual stress in cold-formed pressure vessel steel plates? ? ? ?
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According to GB150, when the cold forming deformation rate of steel plates exceeds the specified value, stress-relief heat treatment is required after forming. The standards are rather vague, and my capabilities are limited; it’s difficult for me to understand and apply them. Please help: 1. What is the deeper meaning of the formula for \"deformation rate\" in the standards? Where does the formula come from? (I tried to derive it myself; it’s the elongation rate of the fibers on the surface of the steel plate.) 2. In practical applications, some people use the degree of deformation as a criterion to determine whether cracking occurs during the shaping of steel plates. Is this correct? For example, if the deformation rate of the vertebral plate is 15%, some people believe that stress-relief heat treatment is necessary during the shaping process, followed by further shaping to prevent cracking during manufacturing. Is this statement correct? 3. Can the stress-relief heat treatment after cold forming of steel plates be carried out together with the post-welding stress-relief heat treatment after welding the plates? 4. Do the residual stresses remaining after cold forming of the steel plate affect the subsequent welding process? (Is it true that the welding process reduces the residual stress in the surrounding base material?) Will it still exacerbate the cracking of the weld? ) 5. Is there a specified time period within which stress-relief heat treatment must be carried out after cold forming of the steel plate? 6. Can a detailed example be given to illustrate the entire standardization process?
It’s obvious this is an expert – being able to come up with so many questions, I really don’t know how to answer them
1. These formulas for deformation rates are all derived from ASME standards; they actually represent the fiber elongation rate. 2. It can serve as a reference to determine whether cracking occurs during the actual deformation process of the steel plate. Carrying out intermediate stress-relief heat treatment will certainly be effective in preventing deformation and cracking. 3. It is feasible when the deformation is small; however, when the deformation is large, a heat treatment to fully restore the properties is required, which is different from post-welding heat treatment. 4. If the residual stress from deformation is too high, combined with the shrinkage stress resulting from welding, it may cause cracking in the base material. 5. No, depending on the actual situation. 6. A special topic should be created.
You are indeed an experienced engineer; the statement regarding \"when the cold forming deformation rate of steel plates exceeds the specified values in GB150, stress-relief heat treatment is required after forming\" is rather rough. It’s difficult to quantify accurately.
A master! The summary is so thorough; I’ve learned something from it.
You’re too kind; it’s just the basics. I still need to learn and improve further: lol