What happens to thick-walled carbon steel pipes if no heat treatment is applied?
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GB50235 specifies that carbon steel with a wall thickness of 19 mm or more requires heat treatment. My question is: in what impact would it have on the properties of the weld if this treatment is not carried out under certain special circumstances? For example, will it crack or have a shortened lifespan?
Thick-walled pipes are prone to delayed cracks after welding. Heat treatment is primarily used to reduce internal stresses; it is generally required to carry out heat treatment first before conducting inspections, otherwise cracks may appear even if the inspection shows satisfactory results! As my knowledge is quite limited, this is for reference only.
Thank you for the reply. I wonder if there are any quantitative analysis results?
Stress-relief annealing at 600℃±20. I can’t feel at ease without doing it, but it depends on the medium and the level of risk. What are the specific materials and locations?
Quantitative? Try to answer this: Hardness testing is used to evaluate the effectiveness of heat treatment. The specific numerical requirements can be found in the SH series of welding standards (3520, 3523, 3525, 3526, 3527) or the installation standards (3501). The most straightforward approach is to measure the hardness of the weld seam, the heat-affected zone, and the base material at a slightly greater distance; the smaller the difference, the better the effect of the stress-relief heat treatment.
It seems the answer is off-target; it’s not the answer the original poster is interested in. As for the consequences, there is no quantitative measurement, so it’s impossible to determine exactly what will happen; it’s merely a matter of probability. Standards are not only a compilation of experimental data, but also a summary of lessons learned, as well as requirements established in light of the current level of materials technology.
There really isn’t! Please ask an expert to answer!