Regarding the issue of preparing heat-treated test pieces for the base material
Thread Content
Experts, we are dealing with a container with a diameter of 500 mm and a thickness of 30 mm; the material used is Q345R, and it is required to be used in the normalized state. The design requirements specify that if the head and cylinder are hot-formed, they should be normalized after forming; if they are cold-formed, they should undergo heat treatment to restore their properties. Additionally, heat treatment specimens of the base material must be prepared separately. The current issue is that, for thermoforming, we believe a plate-shaped base material heat-treated specimen should be used to ensure representativeness. But in the case of cold forming, can preparing a plate-shaped specimen represent the recovery behavior of a head or a cylinder? Have you all encountered similar problems? I would appreciate your guidance; thank you!
Thermal forming of compressed components does indeed require heat-treated test pieces of the base material, but it makes no sense to hear that cold forming also requires heat-treated test pieces; there is clearly an error in the design.
According to clauses 8.1 and 9.2 of GB150.4, if cold forming is employed, heat treatment to restore properties is required; therefore, test pieces of the base material for heat treatment are necessary.
Well, I got it wrong; clause 8.1 of GB150.4 also has restrictive requirements.
Personally, I think the cylinder sheet is acceptable, but the head is not
I’m also very confused. I heard that during the certification review this year, experts suggested that for similar cylinder heat-treatment test plates, a piece should be rolled into the same shape as the cylinder before sampling is taken. I think it’s okay to do it this way for the cylinder, but there are no specific regulations on it. How is the end cap made? Surely they won’t also ask to press another head for sampling, right? ASME’s requirements for heat treatment to restore the formability of carbon steel and low-alloy steel after cold working are the same as those for post-weld heat treatment. Why do our standards establish a theoretical recrystallization temperature when such a requirement is difficult to implement in practice? I’m speechless.
I once raised this question during a standard promotion meeting to the experts at the Regulatory Committee for answers, but the experts avoided it: '(
I’m not sure what others are doing regarding similar issues – are there any new standard interpretations or official responses?
I haven’t encountered such a situation, but it is indeed confusing when such problems arise.
Regardless of how high the cold forming deformation rate is, heat treatment is still required to restore the properties!
I’ve learned it; I hadn’t encountered it before