Problems with post-weld heat treatment of Q345R steel plates
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According to Table 5 of 8.2.2.1 in GB150.4, for Q345R material, when the plate thickness is greater than 32 mm, its butt joints shall undergo post-weld heat treatment. If the thickness of the shell in the design is exactly 32 mm, then the actual thickness of the material is likely to exceed 32 mm. In such a case, is it necessary to consider heat treatment? In other words, in GB150.4, it is unclear whether the thickness considered here is the nominal thickness or the actual thickness. According to the definition in clause 3.6 of GB150.4, the thickness of steel refers to the thickness of the steel plates, steel tubes, or forged components that constitute the container, denoted as δs. From this perspective, it is not the nominal thickness, but rather the feeding thickness. How do you all understand it?
It should be the feeding thickness. It is recommended to subject parts with a thickness in the range of 32–38 to heat treatment; preheating is relatively troublesome and difficult to monitor. Additionally, if the cylinder has this thickness, the thickness of the end caps may be relatively greater, so it is best to carry out heat treatment on the entire structure as a precaution. What do you think?
It should be the actual thickness; different products require different amounts of material to achieve that thickness. It should be calculated based on the actual welding thickness.
Table 5 in 8.2.2.1 of GB150.4 specifies the thickness of the welded joint, which should be the actual thickness of the welded joint.
As for whether to consider post-weld heat treatment when the thickness reaches 32 mm, a comprehensive evaluation is needed; for large containers, overall post-weld heat treatment may not be appropriate, and preheating is also a good option.
It should be the actual thickness; moreover, the issue of stress jumps is similar to this one, so great care must be taken during manufacturing regarding the thickness at the edges.
Is post-heating for that 36mm Q345R necessary?
Is the post-heating at 300°C after welding necessary? Materials like 36mm Q345R
Preheating to over 100 degrees before welding is required, and no post-weld heat treatment is needed. Refer to clause 8.2.2.1 in GB/T150.4.
Attention should be paid to the thickness of the weld and the head, as well as the issue of stress jumps, which is similar to this problem; therefore, great care must be taken regarding the thickness at the edges during the manufacturing process.